Site hosted by Build your free website today!


Important Notice: The Hanford Health Information Network (HHIN) closed in May, 2000. HHIN Web pages are provided as archived information only, and are not currently maintained. Information contained on the HHIN Web pages may be out-of-date.

All HHIN publications are available.

Hanford History and Information about Releases of Radioactive Materials into the Environment: 1944-1972

The Release of Radioactive Materials from Hanford: 1944-1972 -- Summarizes Hanford's history and the release of radioactive materials.

Timeline of Major Events Related to the Release of Radioactive Materials from Hanford -- Significant dates and events in Hanford's history and radioactive releases, and related issues.

Hot Spots: Weather and Hanford's Radiation Releases to the Air -- How hot spots might have affected the amount of radiation a person received from Hanford.

The Release of Radioactive Materials from Hanford: 1944-1972

Historical Background

Air Releases

Green Run

Table I - HEDR Estimates of Radiation Released into the Air

Columbia River Contamination

Table II - HEDR Estimates of Radiation Released into the Columbia River

Soil and Groundwater Contamination

Downwinder Perspective

Reviews of the HEDR Project

Sources of Uncertainty

Table III - Range of Uncertainty: HEDR Estimates of Air Releases from Hanford, 1944-1972


This report presents information on the release of radioactive materials into the environment from Hanford's historical operations (1944-1972). While smaller releases have continued since 1972, the Congressional mandate for the Hanford Health Information Network (HHIN) limits the Network to providing information about the releases of radioactive materials from 1944 to 1972. This publication provides a brief historical sketch and describes Hanford's releases into the air, water and soil. The last section discusses the uncertainties in the estimates of the amount of radioactive material released and whether the government continues to withhold important information.

Historical Background

In 1943, the U.S. government chose a location in southeastern Washington state for the Hanford Nuclear Reservation, now known as the Hanford Site. The federal government condemned privately-held property and moved the residents so it could build plants to make plutonium. Because of the wartime secrecy, few people knew why Hanford was built. It was not until August 6, 1945, when the United States dropped an atomic bomb on Hiroshima, Japan, that area residents and most Hanford workers learned that Hanford made plutonium.1 Hanford had begun making plutonium in September 1944, when the B reactor began operating. Hanford plutonium was used in the first atomic explosion in July 1945 at Alamogordo, New Mexico, and in the bomb that was dropped on Nagasaki, Japan (August 9, 1945).

For more than 40 years, Hanford released radioactive materials into the environment. Although Hanford's mission of making plutonium became public knowledge in 1945, most of the public and some Hanford workers did not know about these releases until 1986. In February 1986, the U.S. Department of Energy, in response to public pressure and a request under the Freedom of Information Act, released 19,000 pages of documents, some dating back to World War II. These documents revealed that releases of radioactive materials from Hanford had contaminated the air, the Columbia River, and the soil and groundwater.

Citizen activists played an important role in making these and other Hanford documents open to the public. In the early 1980s, many citizen groups began to scrutinize the operation of Hanford. One group, the Hanford Education Action League (HEAL), raised numerous questions about the past and present safety of Hanford. HEAL, along with other groups, such as Physicians for Social Responsibility (PSR) and Hanford downwinders, pressed the U.S. Department of Energy for the release of additional historical documents. Journalists, as well as state and Native American governments, also played important roles in the release of Hanford records.

The information in these documents eventually led to the Hanford Environmental Dose Reconstruction Project (HEDR) which began in late 1987. HEDR made estimates of the radiation doses the public may have received from Hanford. The project was beset with public controversy from the start. Citizens leveled charges of conflicts of interest at the U.S. Department of Energy (which owned Hanford and was funding the study), as well as at Battelle Pacific Northwest Laboratory, a longtime Hanford contractor, which was conducting the scientific work. To try to alleviate some of the public's concern, an independent technical steering panel was created to direct the project.2

In 1992, HEDR funding was transferred from the Department of Energy to the Centers for Disease Control and Prevention (CDC). In 1994, Battelle's HEDR contract expired and CDC hired other contractors to complete the study. The HEDR study is scheduled to complete its work in 1998.

A key step in reconstructing doses is estimating how much radioactive material was released to the environment. Scientists refer to the amount released as the source term. By reviewing Hanford's historical documents, HEDR obtained information for making release estimates. The following sections describe these source term estimates for the air, the Columbia River, and the soil and groundwater.

Air Releases

Most of Hanford's air releases came from the routine operation of the chemical plants used to separate plutonium and uranium from used reactor fuel. Some of the air releases came from the nuclear reactors along the Columbia River.3 The major radioactive releases occurred between 1944 and 1957. The largest ones were during 1945, when there were no filters on the stacks of the separations plants. In only five months, Hanford discharged more than half of the entire amount of iodine-131 released during the entire 1944-1972 period.4 Radioactive materials in the form of gases and particles went up the stacks.

Filters were installed in 1948 that greatly reduced, but did not eliminate, the releases to the air. More advanced filters were installed in December 1950 that further reduced the releases. However, the filters would occasionally fail and this would result in some above-normal releases. The largest of these filter failures occurred in the spring and summer of 1951.5

In all, Hanford released over 200 radionuclides.6 Reconstructing past doses from Hanford's releases was a huge undertaking. (By the time HEDR is complete in 1998, it will have cost about $30 million.) To help set priorities, HEDR scientists used scoping studies.

Green Run

Most of Hanford's radioactive releases happened as part of routine operations. But Hanford's largest single release of iodine-131 was the result of a secret military experiment. "Green Run" refers to a secret U.S. Air Force Experiment at Hanford that released somewhere between 7,000 and 12,000 curies of iodine-131 to the air on December 2-3, 1949. The experiment was called the Green Run because it involved a processing "run" of uranium fuel that had been cooled for only a short time (16 days), and was, therefore, "green." The normal practice in 1949 was to cool the fuel 90 to 100 days before processing. The longer cooling time allows for radiation, especially iodine-131, to decay to lower levels.

The reported purpose of the Green Run was to test monitoring equipment the Air Force was developing for its intelligence activities concerning the Soviet Union's nuclear weapons program. The Green Run remained a top government secret until the 1980s when reports were made public in response to Freedom of Information Act requests. The requests were filed by the Hanford Education Action League and the Spokesman-Review newspaper, both based in Spokane. The U.S. Air Force continues to withhold significant information about the Green Run including the names of the official(s) who ordered the experiment and the intelligence unit that participated in the monitoring. The scoping studies were rough calculations of what Hanford released and which radionuclides contributed the most to the public's dose. According to HEDR, most of the radionuclides had little or no effect on public health because: they were released in small amounts; they became non-radioactive quickly; or there was little public exposure to them. For example, krypton-85 and xenon-133 are "noble gases" which do not readily react chemically with other materials. This greatly lessens the potential for these radionuclides to be absorbed by living organisms.

Some radionuclides, while not posing a significant risk to the public, might have been a special hazard to workers, security guards and soldiers at Hanford. This situation is part of continuing HEDR work and a report is expected in 1998.

HEDR estimated the amounts of iodine-131 and other radioactive materials Hanford released into the air between 1944 and 1972. Table I (below) presents the radionuclides for which specific estimates were made. The release estimates are in curies, a unit of measurement of radioactivity. As an example, HEDR estimated that Hanford released about 740,000 curies of iodine-131 from 1944 to 1972. For comparison purposes, the Three Mile Island nuclear power plant accident in 1979 released an estimated 15 to 24 curies of iodine-131, and the Chernobyl accident released an estimated 35 million to 49 million curies of iodine-131 in 1986. Table I also presents the half-life (a measurement of the rate of radioactive decay) of each radionuclide.

HEDR Estimates of Radiation Released
into the Air by Hanford, 1944-1972

TABLE I HEDR Estimates of Radiation Released
into the Air by Hanford, 1944-1972
Radionuclide Amount Released (curies) Half-Life
Iodine-131 740,000 8 days
Tritium (H-3) 200,000 12 years
Cobalt-60 1 5 years
Krypton-85 19,000,000 11 years
Strontium-89 700 50 days
Strontium-90 64 29 years
Zirconium-95 1,200 64 days
Ruthenium-103 1,200 39 days
Ruthenium-106 390 370 days
Iodine-129 46 16 million years
Tellurium-132 4,000 78 hours
Xenon-133 420,000 5 days
Cesium-137 42 30 years
Cerium-144 3,800 284 days
Plutonium-239 1.8 24,000 years


It is important to understand that the amount released is not the same as the dose people received. For example, even though krypton-85 was released in large amounts and has a fairly long half-life, it did not contribute much to dose because it did not deposit on the ground nor contaminate food. HEDR estimated that iodine-131 was the major contributor to dose from the releases into the air. It was released in relatively large amounts. HEDR also estimated doses from five other radionuclides: ruthenium-103, ruthenium-106, strontium-90, plutonium-239 and cerium-144. Members of the public were exposed to other radionuclides. However, HEDR estimated that their contribution to the public's dose was so small that HEDR did not consider it worth the effort required to estimate doses. Due to iodine-131's large contribution to dose, it was the main focus of HEDR's work. The ways people were exposed to iodine-131 included drinking contaminated milk, eating contaminated fruits and vegetables, and breathing contaminated air. Once in the body, iodine-131 concentrates in the thyroid gland.8 The most likely health effect of this exposure is thyroid disease. This is the subject of the Hanford Thyroid Disease Study (HTDS) which is being conducted by the Fred Hutchinson Cancer Research Center in Seattle, Washington, for the CDC. The HTDS is investigating whether thyroid disease is increased among people exposed to the iodine-131 released from Hanford.


Some of the radiation released to the air was attached to particles. The earlier HEDR work did not include particle releases (therefore, the release estimates in Table I will need to be updated). HEDR is studying the releases of ruthenium and plutonium particles.

Most of the ruthenium particles were released between 1952 and 1954. Some were found as far away as Spokane. Particles containing plutonium and other radionuclides were released in large numbers from at least 1945 until 1951. These particles were also found in Spokane as well as on Mount Rainier and along the Idaho-Montana border. For more detail, please refer to HHIN's Potential Health Problems from Exposure to Selected Radionuclides.


In addition to producing plutonium for use in nuclear weapons, Hanford also produced tritium, which is another nuclear weapons material. HEDR reported that Hanford's tritium production resulted in an estimated 200,000 curies being released to the air from the 108-B facility. These releases occurred from 1949 through 1954 with more than half being released in 1954.9

Tritium was also released from the production and processing of plutonium. Air releases from the reactors contained tritium; however, HEDR did not report a total amount released.10 Hanford's plutonium separations plants released tritium to the air as well, but HEDR did not report any estimate for the total amount.

Columbia River Contamination

The first eight nuclear reactors at Hanford used large amounts of Columbia River water to directly cool the reactor cores. The water went through the reactors once and then back into the Columbia River, carrying radioactive materials with it. In addition, radioactive materials that built up inside the reactors were regularly flushed loose during cooling system purges and entered the Columbia River.

These eight reactors were at their highest power between 1955 and 1965. Contamination of the Columbia River was highest during this time. The last of these eight reactors shut down in January 1971.

HEDR estimated that five radioactive substances accounted for most of the dose people received from the Columbia River. They are zinc-65, arsenic-76, phosphorus-32, sodium-24 and neptunium-239. Table II lists these and other radionuclides that were released to the Columbia River. Based upon scoping studies, HEDR decided not to include in the dose estimates the other radionuclides listed here because, in HEDR's opinion, these did not contribute significantly to the dose to the public.

HEDR Estimates of Radiation Released
into the Columbia River by Hanford, 1944-1971

HEDR Estimates of Radiation Released
into the Columbia River by Hanford, 1944-1971
Radionuclide Amount Released (curies) half-life
Sodium-24 13,000,000 15 hours
Phosphorus-32 230,000 14 days
Scandium-46 120,000 84 days
Chromium-51 7,200,000 28 days
Manganese-56 80,000,000
Zinc-65 490,000 245 days
Gallium-72 3,700,000 14 hours
Arsenic-76 2,500,00 26 hours
Yttrium-90 450,000 64 hours
Iodine-131 48,000 8 days
Neptunium-239 6,300,000 2.4 days

People received exposure from the river in several ways:
eating contaminated fish and shellfish, drinking contaminated water, swimming in or boating on the Columbia River downstream from Hanford, or spending time along the river shoreline. According to HEDR, eating fish and shellfish was the main way people were exposed to radiation from Hanford's reactors. For further information, please see HHIN's Radionuclides in the Columbia River: Possible Health Problems in Humans and Effects on Fish.

Soil and Groundwater Contamination

According to the U.S. Department of Energy, about 60 million gallons of highly radioactive waste from the chemical separations plants are stored in 177 underground tanks at Hanford. The tanks contain about 200 million curies of radioactivity. Over the years, more than 1 million gallons, containing over 100,000 curies of radioactivity, have leaked into the soil. At present, it is uncertain whether any of this waste has reached the groundwater.

In contrast to the tank wastes, it is known that much of the groundwater underneath Hanford has been contaminated by radioactive process wastes. The separations plants required large amounts of water to process plutonium and this water became contaminated inside the plants. Hanford has estimated that over 440 billion gallons of these radioactive wastes were dumped into the ground. Some radioactive materials traveled through the soil and entered the groundwater. During Hanford's early years, other radioactive wastes penetrated the groundwater through "injection wells," or shafts drilled deep into the ground.

Tritium is the most commonly found radionuclide in the groundwater at Hanford. Ruthenium-106, technetium-99 and iodine-129 are three of the other radioactive materials commonly found in Hanford's groundwater. Some radioactive substances still remain in the soil and may enter the groundwater in the future.

HEDR concluded that there was little human contact with the contaminated groundwater in the past. In the future, Hanford's groundwater contamination could pose a danger to the public.

Hanford also buried solid wastes in the soil. This waste contains nearly 5 million curies of radioactivity.

Downwinder Perspective

downwinder perspective
Many callers to the Hanford Health Information Lines have questions and concerns about Hanford's releases of radioactive materials. Some downwinders have health problems and believe that these problems are, or might be, related to Hanford. The following personal perspective is offered to help readers understand these experiences and concerns. This perspective is an excerpt from a downwinder's contribution to the Hanford Health Information Archives.

When [my youngest son] was seven--and again when he was eight years old--I had two surgeries for thyroid cancers. I didn't tell people because it would be hard on our children....

In 1985 my husband died quite suddenly. Early in 1986 word got out that radioactive iodine-131 and other pollutants had been released in large amounts by the government just to see what would happen to us downwinders from the nuclear plant at Hanford, Washington.

With the injuries from my thyroid cancers and the worry over my husband's bladder and bone cancers, I was very angry and felt betrayed by my government. They used us as guinea pigs but we weren't even that good because the government never followed up to see what did happen to us downwinders.

I write poems, but they are all too mild for my anger at my government.


It's as safe as mother's milk, they'll say
When wanting to assure you that it's all O.K.
If mom, a downwinder, eats Columbia River's fish,
Or consumes white snow - garden salads on the spot
Then mother's milk can become a deadly lot.

So I fed poison to my nursing son
With radioactive iodine-131.
Just because we lived in the wrong place
I maimed my babe for that nuclear race.

Written by a woman who has lived all of her life in Eastern Washington and remembers consuming local milk and produce. Her husband loved to fish the Columbia River downstream from Hanford. Name withheld by request.

Reviews of the HEDR Project

While HEDR has been the only study to estimate radioactive releases from Hanford, there have been several scientific reviews of HEDR's work. A committee of the National Research Council (NRC) reviewed two summary HEDR reports and concluded that "while the work that went into these reports is impressive, the reports are not adequate in their present form in that some serious questions remain."13 However, the committee did not review all of the background reports that contained key details of how the project estimated the amounts released and the resulting exposures. HEDR's Technical Steering Panel responded with a letter to CDC which said in part: "While we appreciate the NRC review of the Project's work, we are concerned that the review was incomplete and the NRC conclusions are therefore misleading."14

As part of the consolidated lawsuits brought by about 3,000 downwinders against former Hanford contractors, each side has hired scientific experts to prepare reports that assess HEDR's work. The judge hearing the case has also retained a scientific expert. Most of the reports prepared by the experts have not been released publicly. News articles have described one as saying that Hanford released hundreds of times more plutonium than HEDR estimated.15 CDC has told the states of Idaho, Oregon and Washington that "while CDC does not routinely provide formal review and comment on documents related to ongoing litigation issues, CDC staff do review and consider documents such as these for any new technical information they might contain. None of these reviews suggests that there are major unresolved methodological issues associated with the HEDR report produced to date."16

Concerning HEDR's work on the radionuclides released to the Columbia River, another scientist has completed a critique recommending additional 17 This report should be available to the public in 1997.

Sources of Uncertainty

Reconstructing how much radiation Hanford released into the environment is difficult for three main reasons: (1) there are gaps in the historical information; (2) environmental monitoring techniques were being pioneered during Hanford's early years; and (3) so much time has elapsed since the first releases. Because of incomplete knowledge or missing information, there is an amount of uncertainty associated with the HEDR release estimates. This section explains how HEDR reported uncertainty in the release estimates, what was not included in the estimates, and whether the government continues to withhold historical information.

Range of Release Estimates

Scientists generally report their estimates as a range of numbers, from the lowest that is reasonable to the highest. This range of numbers represents how confident the scientists are that their estimates reflect the amounts of radioactive materials that were actually released. If the range from low to high numbers is relatively small, then the scientists are more certain that their estimates accurately reflect what happened. If the range is large, then the scientists are not as certain in their estimates. The HEDR range of uncertainty is large.

Table III - Range of Uncertainty: HEDR Estimates of Air Releases from Hanford, 1944-1972

Table III presents the range of release estimates for the six radionuclides released to the air that HEDR used in its dose estimates. The numbers shown here as "average"are also the ones that were used in Table I.

Range of Uncertainty:
HEDR Estimates of Air Releases from Hanford,
1944-1972 (in curies)
Radionuclide Low Average High
Iodine-131 630,000 740,000 980,000
Ruthenium-103 330 1,200 4,100
Ruthenium-106 110 390 1,400
Strontium-90 23 64 180
Cerium-144 1,400 3,800 11,000
Plutonium-239 0.1 1.8 31.0

The other radionuclides that were released to the air were considered only during the initial scoping studies. The scoping studies do not include enough information to be able to estimate the uncertainty range for release estimates of these other radionuclides.

For the radionuclides discharged to the Columbia River, HEDR did not report the release estimates in such a way that the uncertainty of the estimates can be easily summarized. Those wanting to review the uncertainty in the estimates of river releases can find some of this information in Appendix B, "Monthly Releases from Eight Single-Pass Hanford Production Reactors," in "Radionuclide Releases to the Columbia River from Hanford Operations, 1944-1971," PNWD-2223, dated May 1994.

Are the Estimates Complete? The HEDR estimates do not include all of the radioactive material released to the environment as the result of Hanford operations. The dose reconstruction study did not consider all of the possible sources of release because the study's scientists focused their efforts on the sources that, in their opinion, likely contributed the most to the public's exposure. Additionally, HEDR included only a few of the accidental releases because the study's scientists assumed that the accidental releases did not contribute much to the public's total dose (due to these releases being so much smaller than the huge routine releases).

A question yet to be examined is how the accidental and other releases might have affected Hanford workers and military personnel stationed at Hanford. Because workers and soldiers were closer to the sources of the radioactive releases and were in unique situations, they had different exposures than the public. For example, soldiers at Hanford slept in tents only a few miles from the plutonium plants. This important situation is being considered as part of the remaining HEDR work. This work is expected to be complete in 1998. Is the Government Still Withholding Information?

Many downwinders have asked if the government might still be withholding something about Hanford's environmental releases. Several callers to HHIN over the years have recounted personal experiences (some from former Hanford workers) that are not reported in the historical documents and were not included in HEDR's work. This is yet another source of uncertainty and of unanswered (perhaps unanswerable) questions. If people want to add their own documents, photographs and recollections about their experience of Hanford's releases, they can contribute copies to the Hanford Health Information Archives. The Archives is a joint project of the Hanford Health Information Network and Gonzaga University, which is located in Spokane, Washington. The toll-free phone number is 1-800-799-HHIA (4442).

Even though there may always be questions about whether the government is withholding information about the Hanford releases, the U.S. Department of Energy has made great progress in declassifying historical documents. Over the past three years, it has declassified more pages than it has classified. Under the leadership of then-Secretary of Energy Hazel O'Leary, the department made millions of pages of documents available to the public as part of the Openness Initiative. Of these, about 400,000 pages were declassified by Hanford. Some can be accessed through the Department of Energy.


1 - The atomic bomb that destroyed Hiroshima, Japan, contained enriched uranium from a plant at Oak Ridge, Tennessee.

2 - Ken Niles, "Reconstructing Hanford's Past Releases of Radioactive Materials: The History of the Technical Steering Panel 1988-1995," Technical Steering Panel (TSP) publication, November 1996.

3 - HEDR reported that three radionuclides were the most important: tritium, carbon-14 and argon-41. However, HEDR did not report a total amount released. For details of the work done, see C.M. Heeb, "Radionuclide Releases to the Atmosphere from Hanford Operations, 1944-1972," PNWD-2222 HEDR, May 1994, Section 5.0.

4 - The five months in 1945 were May, August, September, October and December.

5 - PNWD-2222, p. B.3.

6 - For a complete listing of all 237 radionuclides, please see the HHIN publication A Listing of Radionuclides Released from Hanford, September 1996.

7 - Please note that the numbers are all rounded to two significant figures. Sources: W.T. Farris, et al., "Atmospheric Pathway Dosimetry Report, 1944-1992," PNWD-2228 HEDR, October 1994, p. B.4.; B.A. Napier, "Determination of Radionuclides and Pathways Contributing to Cumulative Dose," BN-SA-3673 HEDR, December 1992, p. B.8; M.A. Robkin and B. Shleien, "Estimated Maximum Thyroid Doses from I-129 Releases from the Hanford Site for the Years 1944-1995," Health Physics, Vol. 69 (6), December 1995, pp. 917-922; C.M. Heeb and S.P. Gydesen, "Sources of Secondary Radionuclide Releases from Hanford Operations," PNWD-2254 HEDR, May 1994, Section 7.

8 - More information about iodine-131 and the thyroid can be found in other HHIN publications: An Overview of Hanford and Radiation Health Effects and Health Bulletin.

9 - C.M. Heeb and S.P. Gydesen, "Sources of Secondary Radionuclide Releases from Hanford Operations," PNWD-2254 HEDR, May 1994, Section 7.

10 - For details of the work done, see C.M. Heeb, "Radionuclide Releases to the Atmosphere from Hanford Operations, 1944-1972," PNWD-2222 HEDR, May 1994, Section 5.0.

11 - Please note that the numbers are all rounded to two significant figures. Sources: C.M. Heeb and D.J. Bates, "Radionuclide Releases to the Columbia River from Hanford Operations, 1944-1971," PNWD-2223 HEDR, May 1994, p. vii.

12 - "Historical Perspective of Radioactively Contaminated Liquid and Solid Wastes Discharged or Buried in the Ground at Hanford," TRAC-0151-VA, April 1991. Commonly referred to as the "Wodrich Report." See also M.D. Freshley and P.D. Thorne, "Ground-Water Contribution to Dose from Past Hanford Operations." PNWD-1974 HEDR, August 1992.

13 - Committee on an Assessment of CDC Radiation Studies, National Research Council, A Review of Two Hanford Environmental Dose Reconstruction Project (HEDR) Dosimetry Reports: Columbia River Pathway and Atmospheric Pathway (National Academy Press, 1995), p. 2.

14 - Letter from Mary Lou Blazek (TSP Chair) to Jim Smith (Radiation Studies Branch, CDC), June 21, 1995.

15 - Karen Dorn Steele, "Plutonium Filters Called Defective," Spokesman-Review (June 30, 1996), and Jim Thomas, "Radiation Science Update" in HHIN's Connections (Fall 1996).

16 - Letter from Michael J. Sage (Radiation Studies Branch, CDC) to Stephen E. West (Idaho Division of Health), November 18, 1996.

17 - Jim Thomas, "Radiation Science Update," Connections (Winter 1997).

Published Spring 1997

Timeline of Major Events Related to the Release of Radioactive Materials from Hanford


* Selected Sources for Additional Reading.

* Hot Spots: Weather and Hanford's Radiation Releases to the Air.

This publication offers a year-by-year overview of the major events related to the release of radioactive materials from Hanford, the public's awareness of these emissions and related studies. The timeline was developed in response to questions concerning what happened, and when events took place over the course of Hanford's more than 50 years of history. Following the timeline are lists of abbreviations for agency and project names, and of selected resources for additional reading.





The U.S. government's wartime program to develop the atomic bomb, known as the Manhattan Project (U.S. Army Corps of Engineers), selected the Hanford site in southeast Washington state as the location for its plutonium production operations.


federal court condemned more than 600 square miles of land under the War Powers Act. The area included the towns of Richland, Hanford and White Bluffs. More than 1,500 residents were ordered to leave within 30 days.



Hanford began making plutonium for atomic bombs when B reactor started operating. Radioactive contamination, the by-product of plutonium production, began to be released into the river.


Major releases of radioactive materials to the air and soil began.



The first atomic bomb was tested at Alamogordo, New Mexico, using plutonium produced at hanford.


Bombs were dropped on Hiroshima and Nagasaki, killing over 70,000 people in Nagasaki alone. The Nagasaki bomb contained plutonium produced at Hanford.

By December:

Hanford's plutonium plants released about 560,000 curies of iodine-131 during 1945.


General Electric replaced E. I. du Pont as the general contractor responsible for managing the Hanford site.

The U.S. Congress passed the Atomic Energy Act which made Hanford a civilian operation allowing the Atomic Energy Commission (AEC) and, later, the United States Department of Energy (USDOE), to operate weapons material production plants without independent oversight.


Ten-year expansion of the Hanford site began, including construction of five new plutonium production reactors, two chemical reprocessing plants and 81 underground waste storage tanks.


Filters were placed for the first time on the stacks of the separations plants (where plutonium and uranium were separated from irradiated fuel through a chemical process). The filters helped reduce the amount of radioactive materials released from Hanford.


The dike of a waste pond broke and spilled an estimated 28 pounds of uranium into the Columbia River.



The Soviet Union detonated its first atomic bomb.


The Green Run occurred on December 2-3 at Hanford. It was a planned, top secret release of approximately 8,000 curies of iodine-131. It was the largest single release from Hanford.


In January 1951, the United States started domestic atomic bomb testing at the Nevada Test Site, using plutonium and other materials produced at Hanford. From January 1951 through October 1958, a total of 119 tests were conducted, most of them above-ground. A few above-ground, surface or near-surface tests were also conducted between 1962 and 1968. Fallout from the atmospheric tests released approximately 150 million curies of iodine-131, with peaks in 1953, 1955 and 1957.

1951 To July:

Special iodine filters on Hanford's processing plants began to fail. Before they were replaced in July, about 23,000 curies of iodine-131 were secretly released over Eastern Washington during the height of the agricultural growing season. In the 1990s, the Hanford Environmental Dose Reconstruction (HEDR) Project estimated that 34,360 curies were released in 1951. Scientists serving as experts in downwinder litigation have calculated that the releases may have been as high as 92,100 curies in 1951.



Nearly 250 curies of ruthenium-103 and ruthenium-106 were released at Hanford because of processing problems.


The U.S. Congress passed the Atomic Energy Act of 1954, a revision of the 1946 Atomic Energy Act. This bill allowed weapons material production plants to continue operating without independent oversight.


Releases of over 300 curies of radioactive ruthenium-106 from Hanford's Redox (reduction-oxidation) plant occurred. Some of the ruthenium particles were detected in Spokane, Wash.


The last two of Hanford's original eight reactors started operation. One of the K reactors experienced a partial fuel meltdown at startup.


Approximately 200 curies of iodine-131 were released over two days.


The PUREX (plutonium uranium extraction) separations plant began operation at Hanford.

Late 1950s to mid-1960s:

All of the original eight plutonium production reactors operated at their highest power levels during this time. As a result, contamination of the Columbia River was at its highest. Hanford's releases contaminated fish in the Columbia as well as Pacific oysters in coastal areas of Washington and Oregon.



A "criticality accident" (a self-sustaining nuclear reaction) at the Plutonium Finishing Plant released an estimated 1,200 curies of radioactive gases over three days. Three workers received high exposures inside the plant.


President Kennedy attended the ground breaking for Hanford's ninth reactor (N-reactor) which was designed to produce plutonium and also electricity (from its excess steam).


Short-cooled (green) nuclear fuel was accidentally processed. About 70 curies of iodine-131 were released.


Isochem replaced General Electric as contractor for Hanford operations. General Electric remained responsible for the reactors, however. Also, Battelle took over responsibilities for environmental monitoring.


President Johnson ordered the gradual shutdown of Hanford operations by closing three of Hanford's nine reactors. This prompted local officials to begin economic diversification efforts.


Atlantic-Richfield (ARCO) replaced Isochem for Hanford operations and United Nuclear replaced General Electric for reactor operations.


The AEC closed the last of Hanford's original eight reactors.


The AEC closed the PUREX plant, the last of Hanford's four separations plants.



The Seattle Post-Intelligencer reported that 100 billion gallons of low-level liquid waste were discharged into the ground during 30 years of Hanford operations.


Hanford officials announced that they detected a 115,000 gallon leak from nuclear waste tank 106-T.



The Seattle Post-Intelligencer published a story about an AEC report of at least 60 "unplanned" releases at Hanford, including the 1954 ruthenium-106 release. The story was based on a report frpm the federal Energy Research and Development Administration (publication number ERDA-1538), the first environmental impact statement on Hanford.


Rockwell Hanford replaces ARCO as Hanford contractor.


Stephen Stalos resigned as manager of Hanford's nuclear waste surveillance program charging that the USDOE covered up tank leaks and that the contractor, Rockwell Hanford, used lax safety practices.


The Three Mile Island nuclear power plant had a partial core meltdown and developed a potentially explosive hydrogen bubble. Approximately 15 to 24 curies of radioactive iodine-131 were released to the air.


Hanford became a possible location for a high-level nuclear waste repository authorized by the Nuclear Waste Policy Act of 1982.



The USDOE reopened the PUREX (plutonium uranium extraction) plant in the fall.



USDOE temporarily shut down the PUREX plant, stating initially that the plant was closed because of thorium emissions that exceeded standards. Later it was announced that plutonium emissions prompted the closure.

Spokane Unitarian minister, Bill Houff, delivered his "Silent Holocaust" sermon which led to the formation of Hanford Education Action League (HEAL) four months later. HEAL was a citizen-led, public interest, Hanford-watchdog organization. HEAL was active until 1999.


The USDOE selected Hanford as one of three final candidates for a nuclear waste repository.


The Spokane Spokesman-Review published (on July 28) the first article about Hanford downwinders.


At a public forum held to discuss citizen concerns about the potential health hazards from the radioactive releases, Michael Lawrence, Hanford's USDOE manager, announced that the USDOE would release summary information about Hanford's past emissions.

HEAL and the Spokane Physicians for Social Responsibility (PSR) sponsored a symposium, "Human Health and Hanford" on October 25-26. A few days later, the USDOE announced that the Department would release documents containing raw data about Hanford's radioactive emissions, in addition to the summary information.


The Washington State Nuclear Waste Board passed a resolution calling for an independent health study of Hanford downwinders.



On January 30, HEAL and other groups filed a Freedom of Information Act request for documents to assure and evaluate the USDOE's release of documents already underway.


On February 27, USDOE released 19,000 pages of Hanford Historical Documents which included reports of the radioactive releases. One report from 1974 estimated that Hanford released 441,700 curies of radioactive iodine-131 from 1944 through 1947.


The governors of Washington and Oregon established the Hanford Historical Documents Review Committee. The Committee was asked to review the Hanford Historical Documents and make recommendations about their environmental significance.


An accident at the Chernobyl nuclear power plant in the then-Soviet Union on April 26 released between 40 million and 50 million curies of iodine-131 into the atmosphere.


The Federal Centers for Disease Control and Prevention (CDC) convened the Hanford Health Effects Review Panel to assess the need for studies of long-term health effects in populations exposed to the releases of radioactive materials from Hanford.


The Hanford Health Effects Review Panel made 34 recommendations, which included the need for a dose reconstruction study and an epidemiological study of thyroid disease among people exposed to Hanford's releases.

The Hanford Historical Documents Review Committee, responsible for the follow-up of the Hanford Health Effects Review Panel recommendations, began to design a dose reconstruction study. The USDOE began to design its own study in response to a lawsuit brought by members of the Colville Indian Tribe, and the possibility of other lawsuits. The Colville lawsuit claimed that specific health effects resulted from past Hanford operations.



N-Reactor operations were stopped for safety improvements.

The Hanford Historical Documents Review Committee and the USDOE agreed to conduct one dose reconstruction study instead of two separate studies. It was decided that the USDOE would fund the HEDR HEDR Project and other "feasible and reasonable" health studies. Later, USDOE cut funds to the Documents Review Committee and directed its long-time Hanford contractor, Battelle, to start work on HEDR.

Westinghouse Hanford replaced Rockwell and UNC as main Hanford Contractor.


Hanford was removed from consideration as a site for the high-level nuclear waste repository.


The USDOE issued an order to shut down the N-Reactor.


The Technical Steering Panel (TSP), a panel of scientists which directed the HEDR Project, was appointed and held its first meeting.

Congress mandated funding for the Hanford Thyroid Disease Study (HTDS) through the CDC.


The USDOE, the Environmental Protection Agency, and the Washington State Department of Ecology signed an agreement about the cleanup of Hanford.


HEAL revealed that the PUREX (plutonium uranium extraction) plant had been closed eight months earlier without public notice. Except for a brief stabilization run in 1990, the PUREX plant never resumed operation.


The HTDS began to develop a detailed study plan, or protocol.


Faced with impending disclosure, a Hanford official announced the possibility of a hydrogen explosion in Tank 101-SY. HEAL revealed that Hanford scientists had known since 1979 that potentially explosive concentrations of hydrogen had been building up within 101-SY.


A draft protocol for the HTDS was made available for public review and comment.


The TSP announced preliminary results from the HEDR Project. These results indicated that more than 13,000 people could have received potentially harmful doses of iodine-131 from Hanford's releases of radioactive materials.


The U.S. Congress appropriated $5 million for the states of Idaho, Oregon and Washington to provide information about the Hanford releases and the health effects of radiation to health care providers and citizens who were exposed to radiation from Hanford. This program became known as the Hanford Health Information Network (HHIN).


The USDOE and the Department of Health and Human Services (DHHS) signed a Memorandum of Understanding that established new procedures for the management of federal research on the health effects of radiation and other toxic materials that workers and the public are exposed to as a result of USDOE nuclear operations.



The HTDS protocol was formally approved by the CDC. Data collection began in the fall by the Fred Hutchinson Cancer Research Center, CDC contractor for the thyroid study.

Government investigations and press accounts corroborated the safety concerns and harassment charges of Westinghouse Hanford Company workers who blew the whistle on dangerous situations at Hanford.



The HTDS protocol received approval by the federal Office of Management and Budget. This completed the approval process for the study.


The CDC established a contract with Battelle, officially transferring the HEDR Project from the USDOE to the DHHS.


The HEDR Project announced a revised estimate that 685,000 curies of radioactive iodine-131 were released from Hanford between 1944 and 1947. This represented a 70 percent increase from the original estimate. The new estimate was based on information contained in USDOE documents declassified during the last two years.



The HHIN toll-free information lines opened to the public.



The TSP of the HEDR Project released a second set of dose estimates for representative individuals. In comparison to the 1990 dose estimates, these were lower for people living close to Hanford and higher for people living further downwind. Doses were also calculated for a larger geographic area.


HHIN hosted a major conference on the health effects of radiation. Scientists, health care providers, downwinders and interested citizens met in Spokane, Wash., for this two-day conference which featured 30 sessions and 55 speakers.

The Agency for Toxic Substances and Disease Registry (ATSDR) and the CDC established the Hanford Health Effects Subcommittee (HHES) to advise the two federal agencies on health-related research and public health activities around Hanford.

HHIN was re-authorized by Congress to continue its work through October 1997.


A committee of the National Research Council completed review of the HTDS pilot phase at the request of the CDC and recommended that the study be completed.


The Fred Hutchinson Cancer Research Center completed the pilot phase of the HTDS. Since the pilot phase established that the study was feasible, the full study phase began.

A committee of the National Research Council completed review of selected HEDR Project documents at the request of the CDC. The committee had both favorable comments and criticisms about these reports.

The state health agencies of Idaho, Oregon and Washington and the CDC formed the Individual Dose Assessment (IDA) Project to use the calculations based on HEDR's computer system to calculate individual radiation dose estimates for people who lived or spent time in the HEDR study area. The Project began work on technical issues and to develop and test the necessary computer systems and explanatory materials. (It was determined later that individual dose estimares could be provided for iodine-131 releases to the atmosphere.)


The federal Advisory Committee on Human Radiation Experiments released its final report. While focusing primarily on human radiation experiments, the committee also examined intentional releases of radiation into the environment, including the Green Run at Hanford.


The TSP completed its role in the HEDR Project.



A HEDR Task Completion Working Group, including representatives of Idaho, Oregon and Washington, was formed to work with CDC to continue public participation and assure completion of the remaining HEDR activities.


The Hanford Health Information Archives opened its doors to the public. Located at Gonzaga University's Foley Center Library in Spokane, Wash., the Archives is a public collection of health information and personal records donated by people who lived or spent time in the area exposed to Hanford's releases of radioactive materials between 1944 and 1972. The Archives also launched an Internet site to make its Catalog of Collections and Health Information Database readily available to the public.

Fluor Daniel and five other companies replace Westinghouse as Hanford contractors.


Two projects funded by the USDOE to evaluate the health status of former Hanford workers began. The two are among six pilot projects developing plans for medical screening programs for former workers at USDOE nuclear sites.


HHIN launched an expanded Internet site to make all HHIN publications available online.


HHIN produced its first Spanish-language publication and added a toll-free line staffed by a bicultural, bilingual health educator.

The USDOE launched an Internet site offering federal government historical documents about human radiation experiments and research. These were documents located for review by the Advisory Committee on Human Radiation Experiments, which had published its final report in October 1995.


The ATSDR determined that a medical monitoring program is needed for people who were exposed as children to Hanford's past radioactive releases. The agency determined that past iodine-131 exposure from Hanford met the agency's criteria for medical monitoring. The ATSDR recommended that the Hanford Medical Monitoring Program be a comprehensive program of education and informed decision-making centered on medical screening for thyroid and parathyroid diseases. Funding for the program would need to come from the USDOE.

The ATSDR also began tracing individuals who may be eligible to participate in an Iodine-131 Subregistry. The Iodine-131 Subregistry is to include people who were born in Adams, Benton or Franklin county between 1940 and 1951, or who were under age 6 between 1945 and 1951 and lived more than 30 days within those three counties in those years. The subregistry, part of the ATSDR's National Exposure Registry, will follow these individuals over time to collect information on many different health conditions. ATSDR cannot take further steps until funding is received for the subregistry from USDOE.


SENES Oak Ridge, under a contract with ATSDR, prepared an estimation of health risks from Hanford's releases into the Columbia River. The researchers reviewed the HEDR Project's work and adjusted HEDR's representative doses for the maximally exposed person, whose diet included fresh fish and waterfowl. SENES concluded that the risk to such persons for several kinds of cancer would have been comparable to the risk for thyroid cancer considered as a qualification for ATSDR's Hanford Medical Monitoring Program.

After reviewing HEDR's work on Columbia River exposures for use in the Hanford IDA Project, CDC concluded that additional technical work needed to be done before dose estimates could be provided for people exposed to Hanford's radioactive releases to the river.


On August 1, the National Cancer Institute (NCI) announced results from its nationwide study of iodine-131 fallout from nuclear bomb tests at the Nevada Test Site in the 1950s and 1960s. The study concluded that fallout spread across the country, resulting in a radiation dose from iodine-131 to residents in the 48 contiguous states. The doses were estimated to be highest for people who were young children during the 1950s, who drank milk, and who lived to the north or east of the Nevada Test Site, especially in parts of Montana and Idaho. As a review of the NCI study, the National Academy of Sciences (NAS) and Institute of Medicine (IOM) undertook an assessment of the public health and medical implications.

CDC held a technical workshop on issues related to calculating doses for iodine-131 released to the air. The public was invited to attend.

Members of the Hanford Health Information Archives Advisory Board established a separate nonprofit organization, the Radiation Health Effects Archives (RHEA). The purposes of RHEA are to secure funding to continue the Archives after the close of HHIN, and to expand the Archives to include personal and health histories from people exposed to radiation around the nation and the world.


HHIN (which was scheduled to sunset on October 31) learned that the USDOE had approved its request for extension to operate for the 1997-98 fiscal year. However, HHIN's budget was reduced by more than 40 percent from the prior year. As a result, HHIN scaled back its programs and reduced its staff during the next year.

The HEDR Task Completion Working Group received final reports on two of the remaining tasks to complete the HEDR Project's work. One task was a survey of milk producers in seven counties near Hanford about the cow feeding regimes and distribution of milk to stores and homes. The other task was a scoping study regarding migrant farm workers who worked seasonally in the Hanford region during 1944 through 1951. This was an initial investigation into the demographics, seasonality and lifestyle patterns of these workers.


After reviewing experts' comments from the August technical workshop on iodine-131 dose-related issues, CDC sent a request to the NAS to review and address several specific issues about validation of the HEDR dose model for the iodine-131 air pathway.

The University of Washington sponsored the first annual Health of the Hanford Site Conference, to provide current information on ecological, community and occupational health related to Hanford. Attending were researchers, scientists, health care providers and members of the public. HHIN was a co-sponsor.



The USDOE announced its intention to transfer $5 million to the ATSDR during fiscal year 1998 to initiate the Hanford Medical Monitoring Program, which ATSDR had recommended in 1997. However, this transfer did not occur.

The first phase was completed of two USDOE-funded projects to evaluate former Hanford workers' health status, and Phase II was begun. Phase II involves medical screening for former Hanford workers who had significant workplace exposure to such hazards as noise, beryllium (a toxic metal) and asbestos.


The National Institute for Occupational Safety and Health (NIOSH) released the results of an epidemiologic study of multiple myeloma among USDOE workers at four sties, including Hanford. The study found that there was an increased risk of multiple myeloma for workers who received radiation doses at older ages.


The IOM and NAS issued a report assessing the NCI's study of iodine-131 exposures to the U.S. population from nuclear bomb test fallout from the Nevada Test Site in the 1950s and 1960s. The report concluded that some Americans who were exposed are at higher risk for developing thyroid cancer. The report recommended that the government should not sponsor a systematic screening program for thyroid cancer, noting that the risks of such screening may outweigh the benefits. Instead, the IOM/NAS recommended an informational program on the Nevada tests and the risks of thyroid cancer following exposure to radiation.

Following release of the IOM/NAS report, the Advisory Committee on Energy-Related Epidemiologic Research (a federal citizens' advisory committee) passed a resolution recommending that the government further evaluate offering thyroid cancer screening for people exposed to Nevada Test Site fallout. In addition, the committee recommended that the government take a proactive approach by providing screening for hypothyroidism and other noncancerous thyroid and parathyroid diseases. The committee also recommended completing dose reconstruction for Nevada Test Site fallout (to include dose estimates for other radionuclides, such as strontium-90) and creating an information service for the public and health care providers.

On September 30, the HTDS researchers at Fred Hutchinson Cancer Research Center submitted their draft final report to the CDC. The CDC conducted internal scientific review and requested review from the NAS. The NAS declined to review the draft report until after it was made public.


NIOSH released the results of a study of certain rare cancers in the children of USDOE workers at three sites, including Hanford. The study found no link between the childhood cancers and the fathers' on-the-job exposure to external ionizing radiation.

Congress re-authorized HHIN for up to three more years (1999-2001) but did not earmark any funds for HHIN. The USDOE's Richland office approved part of the funding HHIN had requested for 1999. HHIN determined that this grant would support its programs through July 1999.


On October 29, the Hanford IDA Project began the process of offering iodine-131 thyroid dose estimates to individuals who lived or spent time in a 75,000 square-mile area around Hanford (the HEDR study area) between December 26, 1944 (the start of plutonium production) and December 31, 1957. The Project sent a brochure and a residence history form to everyone on the HHIN and HEDR mailing lists and held two news conferences to publicize the availability of the service.



A committee of the NAS completed review of specific issues related to the HEDR air pathway models for iodine-131. The CDC had requested this review as a result of issues raised at its technical workshop held in August 1997. The NAS committee concluded that the HEDR model was "structurally sound," although "validation studies are not as reliable as desired." CDC concluded that the computer model was sound and should be used by the HTDS and the Hanford IDA Project to estimate individual iodine-131 thyroid doses.

CDC announced that an error had been found in the HEDR dose code and that it would ensure that the error was corrected. The states sponsoring the Hanford IDA Project decided to delay calculating any individual dose estimates until the error was corrected. CDC decided to review other identified potential errors before determining whether further corrections would be done.

On January 28, CDC and researchers for the HTDS announced the findings from the study's Draft Final Report. The study evaluated whether or not the occurrence of thyroid disease was related to different levels of estimated radiation dose among persons who were exposed as children to iodine-131 released from Hanford into the air during the 1940s and 1950s. The study results in the Draft Final Report did not find a link between the estimated thyroid dose from iodine-131 and the amount of thyroid disease in the study population. The study did find thyroid diseases among the HTDS participants. However, those who had higher estimated radiation doses appeared to be no more likely to have thyroid diseases than those who had lower doses. CDC explained that these results do not prove that such a link does not exist.

CDC sent the HTDS Draft Final Report to the NAS for scientific peer review. The NAS report on its review came out in December 1999.

In light of the IOM/NAS report on Nevada Test Site exposures, the HTDS draft results, and discussions with community and tribal representatives, ATSDR modified its proposed Hanford Medical Monitoring Program. The changes would emphasize the program's educational messages and provide information to allow each person to make an informed decision about having a thyroid evaluation performed. No starting date was set for the program, since ATSDR had not yet received funding for it.


HEAL closed its doors, citing waning public interest in Hanford, and a resulting difficulty in raising funds and attracting foundation support. The group donated a set of its newsletters, publications and reports to the Hanford Health Information Archives.


The Hanford IDA Project was re-funded by the CDC to continue offering individual thyroid dose estimates through the end of March 2000. More than 9,000 individuals had completed the first form to request their dose estimate. Also by April, CDC had corrected one of the dose code errors that might affect individual dose estimates, and provided the corrected computer code to the Hanford IDA Project for use in calculating individual dose estimates.


CDC held public meetings in Spokane and Seattle, Wash., to provide information about the HTDS Draft Final Report, correct miscommunications that occurred during initial January 1999 release of the report, respond to questions and take public comment.


The NAS committee reviewing the HTDS Draft Final Report held a public meeting in Spokane, Wash., to take comments from the public.


U.S. Secretary of Energy Bill Richardson announced a proposal to compensate former USDOE workers for diseases caused by their on-the-job exposures. The initial proposal covered beryllium exposures only, but the Clinton Administration formed an interagency group to study whether on-the-job exposures to asbestos and to radiation should be included also. President Clinton asked the group to report its recommendations by April 2000.


ATSDR made public a draft final report of its Hanford Infant Mortality, Fetal Death and Preterm Birth Study. The draft study findings suggest that infants born to mothers living in geographical areas with the highest estimated exposure in 1945 may have had a higher risk for preterm birth, although it was unable to offer a medical explanation for this finding. The study also indicated that living during the latter part of pregnancy in areas with the highest estimated iodine-131 exposure was associated with preterm birth and may also be associated with a small increase in infant mortality. After scientific review, the final report is expected to be completed in the spring of 2000.

HHIN's funding was transferred from USDOE-Richland to ATSDR. Funding was extended through December 1999, with the possibility of an additional two years and with funding decisions to be made annually.


ATSDR decided to take a phased approach to the Hanford Medical Monitoring Program. Phase I activities were to include outreach, education and risk communication messages for health care providers and the Hanford-exposed population. The focus will be on iodine-131 exposure and the risks of thyroid screening. Phase I was also to include an assessment of the needs for education and services for the exposed population. As of this date, ATSDR still had not received funding to implement the medical screening portion of the program.


The Hanford IDA Project began sending out individual thyroid dose estimates to people exposed to Hanford's releases between 1944 and 1957. With more than 10,000 people who had started the dose estimate process by returning their residence history forms, and with the end of the Project's funding on March 31, 2000, the Hanford IDA Project established a waiting list for anyone returning a residence history form after late September.


The NAS completed its scientific peer review of the HTDS Draft Final Report and held a public briefing in Spokane, Wash. The review panel wrote that the HTDS investigators "probably overstated the strength of their findings that there was no radiation effect." The panel found that the study methods were of high quality. However, the panel said that additional analyses are needed to explain what the study data mean about the full range of possible risk to the thyroid. The panel commended CDC for public involvement during the nine years of the study but found shortcomings in the way the report was released. The panel recommended several steps for improving the communication of the final report to the public. A revised HTDS report is expected by December 2000.

HHIN was notified that it would receive severely limited federal funding for 2000 and began preparing to close down.



The New York Times reported that the federal government interagency task force looking at workplace exposures to USDOE workers has concluded that exposure to radioactive materials and chemicals at USDOE facilities led to higher-than-normal rates of cancer among workers. The interagency task force's report was expected to be released on March 31.


Facing a March 31 ending date, the Hanford IDA Project requested additional federal funding through December 2000 in order to provide individual thyroid dose estimates to everyone who sent in a residence history form by January 31, 2000. The Project said it could not accept new requests.

On February 3, USDOE Assistant Secretary Dr. David Michaels held a public meeting in Richland, Wash., to hear from current and former USDOE workers about work-related illnesses and their experience with the state workers compensation program. More than 500 people attended. In addition, USDOE offered a confidential toll-free line where workers could share their information.

March: ATSDR began the Hanford Community Health Project, an outreach and education program related to iodine-131 releases. Assisting ATSDR, the National Opinion Research Center began work to review health care utilization and information needs related to thyroid disease.


May 15 is the last day for HHIN's telephone lines and services. The Hanford Health Information Archives will remain open at least through June 30.

Abbreviations for Agency and Project Names

AEC: Atomic Energy Commission
ARCO: Atlantic Richfield Company
ATSDR: Agency for Toxic Substances and Disease Registry
CDC: Centers for Disease Control and Prevention
DHHS: U.S. Department of Health and Human Services
HEAL: Hanford Education Action League
HEDR: Hanford Environmental Dose Reconstruction Project
HHES: Hanford Health Effects Subcommittee
HHIN: Hanford Health Information Network
HTDS: Hanford Thyroid Disease Study
IDA: Hanford Individual Dose Assessment Project
IOM: Institute of Medicine
NAS: National Academy of Sciences
NCI: National Cancer Institute
NIOSH: National Institute for Occupational Safety and Health
PSR: Physicians for Social Responsibility
PUREX: Hanford's plutonium-uranium extraction plant
Redox: Hanford's reduction-oxidation plant
RHEA: Radiation Health Effects Archives
TSP: Technical Steering Panel for the Hanford
Environmental Dose Reconstruction Project
UNC: United Nuclear Corporation
USDOE: U.S. Department of Energy

Selected Sources for Additional Reading

D'Antonio, Michael. Atomic Harvest: Hanford and the Lethal Toll of the Nuclear Arsenal. New York: Crown Publishers, 1993.

Filby, Roy and Joseph Stohr. "Environmental and Health Studies of Potential Impacts from Early Hanford Operations." Hanford Historical Documents Review Committee, 1987.

Gerber, Michele Stenehjem. On the Home Front: The Cold War Legacy of the Hanford Nuclear Site. Lincoln, Neb.: University of Nebraska Press, 1992.

Heeb, C.M. Radionuclide Releases to the Atmosphere from Hanford Operations, 1944-1972. PNWD-2222 HEDR, May 1994.

Kaplan, Louise. "A Slow Motion Emergency: Radiation Health Effects and Hanford" (Doctoral dissertation). Brandeis University, March 1992.

Loeb, Paul. Nuclear Culture: Living & Working in the World's Largest Atomic Complex. Philadelphia: New Society Publ., 1986.

Rhodes, Richard. Dark Sun: The Making of the Hydrogen Bomb. New York: Simon & Schuster, 1995.

Rhodes, Richard. The Making of the Atomic Bomb. New York: Simon & Schuster, 1986.

Stohr, Joseph. "Chronology of Events." Washington Department of Ecology memorandum, 1988.

Technical Steering Panel of the Hanford Environmental Dose Reconstruction Project. Representative Hanford Radiation Dose Estimates. Washington Department of Ecology, Nuclear Waste Program, April 21, 1994.

Thomas, Jim. "Hanford Historical Timeline." HEAL Perspective. Summer/Fall 1992, pp. 14-15.

Thomas, Jim. "Radiation from Hanford: A Chronology." HEAL Perspective. Fall 1990, page 7.

Published March 2000

Hot Spots: Weather and Hanford's Radiation Releases to the Air -- How hot spots might have affected the amount of radiation a person received from Hanford.

* Hot Spots: Weather and Hanford's Radiation Releases to the Air.

The Hanford Nuclear Site in southeast Washington state released many radioactive substances to the air for more than 40 years. This fact sheet discusses how weather affected where the radioactive materials went and how "hot spots" might have formed. "Hot spot" is a term used to describe an area where the concentration of contaminants is greater than that in the surrounding area. Those contaminants can be either radioactive materials or toxic chemicals. As used here, the term "hot spot" refers only to radioactive materials from Hanford.

This fact sheet discusses how hot spots might have affected the amount of radiation a person received from Hanford. It explains how the effects of weather can create situations where, for at least periods of time, people living farther from Hanford could have received higher exposures than people who lived closer to Hanford.

This publication is intended to serve as an introduction to the subject of weather and hot spots. The Network also offers a publication on the history of Hanford's releases: The Release of Radioactive Materials from Hanford: 1944-1972. For those who wish to do further reading, a bibliography of books and articles concerning the topics discussed in this fact sheet is available.

Hanford began operations in 1944. Since then, scientists have measured the amount of radioactive contamination in the environment. Unfortunately, this information is not detailed enough to identify where Hanford's radiation went.

The Hanford Environmental Dose Reconstruction Project was established to estimate where Hanford's radioactive materials went and how much radiation people may have absorbed. The Dose Reconstruction Project selected an area in Washington, Idaho, and Oregon.

Computer models simulate the likely spread of Hanford's radiation. The models use mathematical calculations and historical weather information. Additional models use this and other information to estimate the radiation exposures people could have received. This is known as a "dose estimate."

The Hanford Environmental Dose Reconstruction (HEDR) Project was established to estimate what radiation dose people living near Hanford some time between 1944 and 1992 might have receivied from releases of radioactive materials. The Technical Steering Panel, which directed the study, completed its role in 1995. The federal Centers for Disease Control and Prevention (CDC) is now working with the HEDR Task Completion Working Group to continue public participation and to assure completion of the remaining HEDR activities.

Before describing how well the computer models handle weather and hot spots, a basic explanation of the behavior of pollutant materials in air is needed.


When the radioactive pollution from Hanford's plutonium separations plants reached the top of the 200-foot smoke stacks, it began to be affected by the weather. The stability of the surrounding air, the wind speed and direction, and whether it was raining or snowing all influenced where and how much of Hanford's radiation fell back to earth. Stability of the Atmosphere

Under different conditions, the atmosphere can be stable or unstable. Each influences how pollution spreads after it leaves a plant's smoke stack. Under stable conditions, airborne pollution diffuses relatively slowly. In the air near the ground, this tends to occur more often in the winter, especially during the night.

Under unstable conditions, pollution diffuses relatively rapidly. In the air near the ground, this tends to occur more often in the summer, especially during the day.

At Hanford, most of the emissions occurred at night when the air was cooler at ground-level than at the top of the stack. Hanford officials ordered night-time releases to make it less likely that the radioactive pollution would fall back to earth near the operating plants, which could have caused serious exposure to workers.1 While night-time releases tended to protect workers, the wind carried more radiation beyond the Hanford site to public areas than if the plutonium operations had been done during the day.

Wind Speed and Direction

The primary factors in determining where Hanford's radiation releases to the air went are the speed and direction of the wind. The wind's importance is symbolized by the fact that people who were or may have been exposed to radiation are referred to as "Downwinders."

The direction of the wind determines where the pollution is carried. Based on what is currently known, the wind generally blew southeastward from the Hanford stacks to the Tri-Cities, toward Walla Walla, and then turned northeast toward Spokane and Northern Idaho. Places outside of this pattern, such as Yakima, did not receive as much of Hanford's airborne radiation. (See map of areas exposed.)


Four main factors lead to the creation of hot spots: precipitation, wind patterns, stagnation, and impaction.

Now that we have a general idea where the wind blew Hanford's radiation, how might the radioactive material have concentrated into hot spots? Common sense suggests that as one moves farther from a pollution source there is a decrease in the amount and concentration of that pollution. This is due to some of the material falling back to earth and the remainder becoming more mixed with the surrounding air. In general, Northern Idaho received less fallout from Hanford than areas around Eltopia or Ritzville in Washington.

However, this was not always true. Because of variations in the wind patterns and the earth's surface (hills, valleys, etc.), the spread of radiation, even in the downwind direction, was not uniform. Recall that the term "hot spot" refers to an area that has more contamination than does the surrounding area. People who lived in a hot spot area or got their milk or other food from such an area could have been exposed to higher levels of radiation than others who were not affected by a hot spot. Four main factors lead to the creation of hot spots: precipitation, wind patterns, stagnation and impaction. Each is described below.


Snow and rain can wash radioactive substances from the air and deposit the contamination on vegetation and the ground. When the wind carried radioactive material from Hanford over an area where it was raining or snowing, that area could have received a greater concentration than the areas around it. The surrounding areas might not have experienced any precipitation or were not in the path of the wind-blown radioactive plume.

To illustrate this, let's use September 9, 1945, when Hanford released 1,658 curies of iodine-131. Assume that winds could have blown some of the iodine over the town of Ritzville (a distance of about 70 miles from Hanford, as the crow flies). Assume, also, that there was a rain shower over Ritzville at the same time and it washed much of the iodine from the air. This could have created a hot spot at Ritzville on that day.

Or, if it rained on Ritzville but the winds had carried Hanford's radiation toward Walla Walla that day, there would have been little or no additional contamination at Ritzville.

Wind Patterns

In the case of releases of pollution lasting many minutes or hours, the wind direction could change during this time. In some instances, the change in wind could send the pollution plume in two or more directions. Later, the winds could change speed and direction again and cause the plumes to combine over a particular area and form a hot spot.

This combining of plumes could be part of a regular weather pattern. If this were the case, then a particular area could have become a routine hot spot. A scientist in charge of developing computer models for calculating doses for the Hanford Environmental Dose Reconstruction Project believes that the Spokane area was possibly a hot spot of this type.


When the wind carrying radioactive material becomes calm, the radioactive plume may remain over a particular area for a longer time. The lack of wind would allow more radiation to deposit in one particular area, possibly creating a hot spot.

According to Dose Reconstruction Project scientists, this factor may have led to a hot spot over Walla Walla soon after the large Green Run release of iodine-131 in early December 1949.2 The winds carrying the iodine-131 died down over Walla Walla for several days before carrying the remaining radioactive material toward Spokane, Northern Idaho and Canada.


Impaction occurs when the pollution plume meets the side of a hill or mountain. The contamination is deposited in greater amounts where the plume meets the side of a mountain than in other areas at the same elevation. It is well established in Hanford documents that this frequently occurred on Wahluke Slope (north of the Columbia River, across from the Hanford reactors) and on Rattlesnake Mountain (the southern border of the Hanford site).


It is nearly impossible to determine where hot spots actually occurred around Hanford over 40 years ago. The Hanford Environmental Dose Reconstruction Project's computer programs (used to calculate the spread of Hanford's releases to the air) cannot reliably predict when or where a hot spot may have occurred. Part of the reason for this is the limited precipitation data. In addition, the air modeling part of the computer programs does not directly take into account the effects of hills or mountains (impaction).

There is only enough historical information to reconstruct the general pattern of contamination resulting from Hanford operations. It is impossible to be more specific given the time that has passed and the large geographical area that was exposed.

Besides iodine-131, Hanford released other substances into the air, including plutonium and ruthenium particles.

Estimating whether or not there were hot spots might not really change the dose estimates for individuals from exposure to iodine-131. The main reason is that iodine-131 has a relatively short half-life of only eight days. A half-life is the amount of time it takes for a radioactive substance to decay by releasing radioactive particles or waves, and to lose one-half of its radioactivity. Another reason is that the Dose Reconstruction Project is adding an individual's dose over a full year or a lifetime.

It is important to remember that where people's milk and fresh leafy vegetables came from may be more important in estimating doses of iodine-131 than the exact location in which a person lived and worked. Non-Iodine Air Releases

Besides iodine-131, Hanford released other substances into the air, including plutonium and ruthenium particles. Historical documents from the 1940s and 1950s revealed that government officials considered both particle problems to be serious. John Till, Chair of the Technical Steering Panel which directed the Dose Reconstruction Project, and Charles Miller of the Centers for Disease Control and Prevention (CDC) have recommended an in-depth study of this problem. In a report to the Technical Steering Panel, they stated: "The active particle problem at Hanford will require a very thorough and careful analysis." Because the current computer models do not handle particles, a special effort is underway to estimate doses from the plutonium and ruthenium particles.

The factors leading to the formation of hot spots are the same for these particles as they are for iodine. However, hot spots of plutonium or ruthenium particles could be of greater concern than hot spots of iodine-131. This is because they have much longer half-lives and thus decay more slowly than iodine-131 (the half-life for ruthenium-106 is 372 days; for plutonium-239, the half life is 24,000 years). This causes greater concern for exposure to humans because ruthenium and especially plutonium are in the environment for a long time. Effects on Dose

Generally, the closer to Hanford a person lived in a downwind direction, the greater the exposure to airborne releases. However, those people living in the primary downwind direction or in a recurring hot spot may have received more exposure than those in other areas.

Where you lived is only one factor in determining your exposure to Hanford's radiation. It is also important to think of the time periods you lived in a particular place, what foods you consumed and where they came from, and whether there were other unique characteristics about your lifestyle that could have affected your exposure to radiation.

1. The practice began in May 1945 after two serious instances of worker contamination. Operation of Hanford Engineer Works, S Department, 1946 (known as the DuPont History). It is uncertain how long officials continued the the practice of night-time releases.

2. The Green Run was the largest single release of iodine-131 from Hanford (about 8,000 curies). It was part of a secret program by the intelligence agencies of the United States to develop ways of detecting radiation from Russia's nuclear weapons program. It is called "green" because the nuclear fuel dissolved during the experiment cooled for only 16 days after leaving the reactor. The usual practice at the time was 90-100 days. The length of the cooling allowed iodine-131 and other radioactive materials to decay. Certain key details of the Green Run are still classified. Selected Sources:

* LIPNWD-2033 HEDR Vol.2, Iodine-131 Releases from the Hanford Site, 1944 through 1947, Volume 2 - Data, March 1993, p. 7.51.

* Meeting transcript for Van Ramsdell's presentation on hot spots to the Technical Steering Panel, Richland, WA, October 8, 1993, pp. 273, 274, 276, and 280-282.

* Dickeman, R.L. HW-42185, Meeting with Advisory Committee on Reactor Safeguards, March 1, 1956. Dated March 22, 1956, p.8.

* Memo from John E. Till and C. W. Miller to TSP. "Active Particle Problem at Hanford." Undated, p. 1.

Published Spring 1994

An Hanford History and Information about Releases of Radioactive Materials into the Environment: 1944-1972 partII

Click Here to Search This Site


Overview of Radiation and Known and Potential Health Effects
Health Care: Finding a Provider and Getting Health-Related Records
Coping with Uncertainty and Illness
Monograph for Health Care Providers
Earth Facts
My family
Web Sites
Q Goo
Java Jukebox
Please Sign My Guestbook