Pokhran II : Chemical Engineers' Contributions
Amid the recent incident of nuclear bomb blasts, it is
interesting to note the following excerpt, which appeared in Janes' -
the comprehensive missile sourcebook, referred widely for trade and
development in missile technology. Importantly, this appeared 4 months
earlier and showcases India's potential towards making a fusion (Hydrogen)
bomb. That what happened now, 4 months later, is indeed what had been
predicted in the following report, is for all of us to see.
The reason I want you to read the article is, it involves a success story
of Indian scientists, and indeed of a group of Chemical Engineers
at BARC. They have developed a very low cost method of producing gaseous
Tritium, which apparently is used in thermonuclear weapons like
hydrogen bomb. Specifically, the team developed a hydrophobic catalyst
which produces enriched tritium gas from heavy water, the latter being a
by-product from nuclear reactor coolants and is abundant in India.
India thus possesses a very cheap and easy source of tritium, critical for
nuclear weapons, which beats the Americans hands down in terms of the
production method and costs. And this is indigeneous technology, starting
from producing tritium to finally recovering an enriched gas-stream
through a cascaded sequence of 3 multicomponent distillation units,
comprising of 240 stages!
Regards,
Rajdip.
TRITIUM BREAKTHROUGH BRINGS INDIA CLOSER TO AN H-BOMB ARSENAL
Source: Janes Intelligence Review, January 1998
Nestled between the nuclear capabilities of China and the nuclear
aspirations of Pakistan, India would seem to be in an unenviable strategic
position. As T.S. Gopi Rethinaraj reports, however, a breakthrough by
Indian scientists in the economical production of tritium may have
tipped the strategic scales in New Delhi's Favour.
The importance of tritium as a strategic material in the creation
of thermonuclear weaponry, given the insignificance of its other
uses, cannot be overstressed. Its importance becomes even more
apparent when one considers the major leap from the ability to
manufacture fission weaponry to the capacity to build a
thermonuclear weapon like a hydrogen bomb. It is within this
context that the pioneering work in extracting highly enriched
tritium conducted by scientists at India's Bhabha Atomic Research
Center (BARC) assumes significance. In this area at least, Indian
scientists have reason to cock a snook at the USA. While the USA
had stopped producing tritium by about 1988 due to safety reasons
and ageing facilities, the Indian breakthrough underscores the
fact that tritium can now be produced at a fraction of the
estimated US$ 7 billion needed to produce the isotope at current
costs using the accelerator process, as was done in the USA. The
Indian scientists have managed to extract, highly enriched
tritium from heavy water used in power reactors. The advantage of
the technology developed by BARC is that it assumes heavy water
as the moderator in power reactors when most of those in the West
(including Russia) - with the exception of Canada - use light
water. The other advantage is a short gestation period; the
Indian tritium facility takes less than two years for completion.
This is not to say that India has already secretly developed the
H-Bomb, but the very fact that tritium, according to all
available indications, is now being stockpiled puts India in a
comfortable position in terms of nuclear deterrence, given the
nuclear ambitions of Pakistan and the already - nuclear China.
On the trail of Indian Tritium
It was an innocuous paragraph at the end of a recently published
paper on detritiation that let the cat out of the bag. The paper
appeared in a book entitled Heavy Water- Properties, Production
and Analysis, which was authored by two BARC scientists, Sharad
M. Dave and Himangshu K Sadhukhan, with a Mexican scientist,
Octavio A Novaro. On p461 of the work, it says the following:
The Bhabha Atomic Research Center, Bombay, India, also having
developed a wetproof catalyst for LPCE liquid phase catalytic
exchange, has employed it for detritiation. A pilot plant based
on LPCE cryogenic distillation with about 90 per cent tritium
removal from heavy water has been commissioned and is under
experimental evaluation. Reportedly, this facility seems to be
the only operating LPCE-based detritiation facility in the world.
A commercial detritiation plant based on this process is being
set up at one of their nuclear power stations.
According to BARC scientists, the new technology is aimed at
lowering the tritium content in heavy water circulating around
the moderator circuit. They argue that the project is being
executed to prevent the many health hazards associated with the
leakage of tritium from reactors. When asked what is exactly
being done to the highly radioactive tritium so recovered, the
scientists refuse to talk - even under conditions of anonymity.
When pressed, some ventured to comment that a scenario in which
the recovered tritium is being stockpiled for strategic purposes
cannot be ruled out.
Curiously, there seems to exist some confusion regarding how
classified the project is, but scientists at the Nuclear Power
Corporation (NPC), the government controlled organization that
constructs and runs India's commercial power reactors, remain
tight-lipped on the entire issue. Both A Sanatkumar and C
Surendar, group directors at NPC, said the same thing: "We are
unable to understand what you are talking about. There is no such
project at Kalpakkam".
When the author contacted the managing director's officers said:
"Please don't ask anything about the detritiation plant. We have
been asked not to talk about it". However, there was no
categorical denial of such a project being at the implementation
stage. Incidentally, some time ago, the NPC management announced
that one of the power reactors at Kalpakkam near Madras in
southern India would be opened to research activities. According
to highly placed sources, the commercial version of the pilot
plant is taking shape at Kalpakkam. Recently, labour trouble hit
the plant with the workers striking for nearly a month because of
alleged high levels of radioactivity. Employees working in the
station are still puzzled as to why their dosimeter readings have
increased in recent times. Dr. Rajagopalan Chidambaram, Chairman
of the Atomic Energy Commission (AEC), evaded probing questions
relating to the project. When asked persistently, he admitted:
"Yes, there is a pilot plant for detritiation of heavy water in
BARC" Asked whether the project is meant for stockpiling tritium,
he replied: "No Comment". Also refusing to comment when asked
about the project was former AEC chief P K lyengar, one of the
pioneers of India's 1974 fission bomb experiment.
With eight operating Pressurized Heavy Water Reactors (PHWRs) at
Kalpakkam, Rawatbhatta, Narora and Kakrapar plus more to come in
future, India has struck a gold mine in tritium production, as
the BARC pilot plant can be implemented at all of these power
stations. Scientists say that the size of the commercial plant
would be just two or three times the size of the pilot plant.
According to technical estimates, 2400 curies of tritium could be
produced for every MW of electricity produced in heavy water
reactors. Since, unlike fission bombs, fusion bombs have no
critical size, bombs of various intensities could be fabricated
using tritium. Fusion bombs require an ambient temperature of 100
million 0C to overcome the Coulomb Repulsion Barrier (CRB) which
prevents lighter atoms from coming together - meaning that
fission bombs are a prerequisite for detonating fusion, bombs.
India first demonstrated its capability to explode fission bombs
in 1974 in the deserts of Pokhran in Northwest India. Under the
circumstances, the inference is inescapable: that the
breakthrough in BARC puts India on the road of self-sufficiency
in terms of strategic materials for defence purposes. It is
another matter that Indian scientists are loath to call it
'production' of tritium, but instead choose to talk of
'detritiation'. "Look, our intention is not to produce tritium,"
said a senior scientist directly involved with the pilot
detritiation plant at BARC. "Our aim is to lower the tritium
content in the heavy water, which gets contaminated after fission
and neutron capture by deuterium atoms. If tritium comes out as a
by-product, what can we do about it?" Asked what was to be done
with the tritium so obtained, the scientist just smiled.
Tritium
Tritium is a radioactive isotope of hydrogen with a half-life of
12.3 years, meaning that 5.5 per cent of tritium will decay into
helium-3 every year. Deuterium, another isotope of hydrogen,
along with the elementary gas itself, is stable and
non-radioactive. Tritium decays and is converted into a
non-radioactive form of helium.
Although tritium is present naturally in the environment, this
amount is too small for practical recovery. Therefore, tritium
required for strategic purposes has to be produced artificially,
and there are two ways to do this, both involving nuclear
reactions with neutrons: in the first method, neutrons are made
to strike a target of lithium or aluminum metal, which gives
tritium and other by-products; the second method involves a
neutron reaction with helium-3 which gives tritium and hydrogen
as by-products.
The first method is widely used an was employed for several years
at the Savannah River Site (SRS) in the USA before it was shut
down in 1988. The production of tritium requires the generation
of energetic neutrons, the source of which can be either power
reactors or accelerators. In reactors, neutrons are produced as a
result of fission, while in accelerators they occur as a result
of spallation, where protons strike a metallic target and 'kick
off' neutrons from the metal. Tritium finds peripheral use in
medical diagnostics, but it is mainly used in the construction of
hydrogen bombs and to boost the yield of both fission and
thermonuclear weapons. Contained in removable and refillable
reservoirs in nuclear arsenals, it boosts the efficiency of the
nuclear materials. Although no official data is available on
inventory amounts of tritium.
each thermonuclear warhead is said to contain 4 g of the isotope.
However, neutron bombs designed to release more radiation will
require 10-30 g of tritium, according to a status report prepared
by the US Department of Energy's Science Policy Research Division
and an assessment made by the Institute for Energy and
Environmental Research (IEER) in Maryland, USA.
Authoritative US reports put the USA's total tritium production
since 1955 at 225 kg. After decay, it is now left with 75 kg of
tritium, which is sufficient to take the country through the
first quarter of the next millennium.
Even in low levels, tritium has been linked to developmental
problems, reproductive problems, genetic and neurological
abnormalities and other health problems. Additionally, there is
evidence of adverse health effects on populations living near
tritium facilities. Tritium contamination has been reported at
the Savannah River site in ground water soil from operational
releases and accidents. No figures are available relating to the
Indian stockpile of tritium, however. The pilot plant at BARC was
set up, according to well-placed sources in the department, in
1992.
India's Breakthrough
India has now acquired a unique place in the annals of tritium
production. Lacking the 'big money' to go in for
capital-intensive methods, India's economic position - combined
with the hostile attitude it faced from the West following the
country's refusal to sign the Nuclear Non-Proliferation Treaty,
Comprehensive Test Ban Treaty and Fissile Material cut-off Treaty
- has taught Indian scientists to rely on economically viable
indigenous methods. They therefore decided to extract tritium
from moderator heavy water in power reactors, which is plentiful.
This year India exported 100 tons of heavy water to South Korea.
India's three-stage nuclear planning has come in handy for the
project: in the first stage Indian power reactors use natural
uranium; the second stage employs fast breeder reactors that will
use plutonium from the first stage; finally, the third phase aims
at using thorium, since India has abundant thorium reserves in
the beach sands of Kerala and Orrisa. The first stage uses
reactors moderated by heavy water, and it is in these reactors
that Indian scientists have struck a gold mine in tritium
production.
The tritium build-up in these reactors increases with the number
of years of plant operation. The pilot plant is called the
detritiation plant because the process involves lowering tritium
levels in heavy water, but the fact remains that the by-product
is highly enriched tritium. The reason why BARC developed new
technology was to reduce radioactive levels by lowering the
tritium content in heavy water. The department set up a pilot
plant to achieve this and struck pay dirt: enriched tritium at
low cost which needed only additional detritiation plants ton be
added to the country's already-available nuclear infrastructure.
The BARC technology is all the more laudable in that it is 100
per cent indigenous and the first of its kind anywhere in the
world, according to experts preferring to remain anonymous.
Scientists at BARC's Chemical Engineering Group recently
developed a wet-proof catalyst for LPCE (the process that yields
highly enriched tritium from heavy water), but they refrained
from talking about the defence implications of the project. They
have called the facility a detritiation plant to avoid charges of
stockpiling a strategic raw material crucial in the production of
thermonuclear weapons.
The Process
The presence of tritium in heavy water has been a major concern
of reactor engineers in India for a long time. During the
operation of a PHWR, tritium is produced as a result of fission
and irradiation of reactor components with neutrons. This tritium
remains in the fuel and later passes into the effluents in the
fuel reprocessing plants. The BARC pilot plant produces tritium
using moderator heavy water, where tritium is produced due to the
capture of neutrons by deuterium atoms in the water. This
reaction, as reported in scientific literature, is known to yield
maximum tritium.
Although any method employed in the production and enrichment of
isotopes can also be used in the case of tritium, the BARC
scientists' choice of process was governed by safe handling and
economic reasons. BARC scientists first worked with the water
distillation and electrolytic method, which proved to be risky
and inefficient. This produces tritium in its most hazardous
form: liquid. They instead settled for the method of chemical
exchange followed by cryogenic distillation. In this method the
tritium is in a liquid phase only for a short time during the
chemical exchange process, with the final product collected in
gaseous form and kept in double containment to ensure safety.
This method yields 90 per cent enriched tritium. It is worth
noting that weapons also use tritium in its gaseous phase.
The Catalyst
The most important hurdle in producing tritium by this method is
finding a suitable catalyst for the process because heavy water
from the moderator and pure deuterium gas have to pass through
the column containing the catalyst. Besides, the exchange
reactions of deuterium between hydrogen and water require a slow
and suitable catalyst, taking into account the slow nature of
these reactions. Nickel coated by chromium, platinum or other
noble metals supported on silica or activated charcoal have been
found effective for vapour phase exchange reactions, but BARC's
exchange reactions occur in the liquid phase and require some
other species of catalyst. All the catalysts mentioned above lose
their activity in contact with liquid water and prevent hydrogen
from reaching them. Indian scientists have overcome this problem
by imparting hydrophobicity to the catalysts. Since water in the
liquid form wets and contaminates the catalyst, the suitable
solution was a wet proof catalyst, which is what the BARC
scientists opted for. A number of technical snags associated with
the poor choice of catalyst have been eliminated, and experiments
conducted to check the performance of the catalyst have shown
positive results. Although the department undertook this work in
the early 1970s, it was only recently that they perfected the
technology.
Design
The pilot plant's equipment is indigenously designed. Scientists,
have taken into consideration various aspects of handling
inflammable gases like hydrogen, deuterium and the radioactive
tritium. Pipelines, fitting-valves and other equipment are made
of special steel, all suitable for cryogenic conditions. The
entire cryogenic part of the plants is housed inside a
vacuum-insulated enclosure, which provides thermal insulation for
its components. The column sections have been insulated with
mylar to prevent any cold leak.
Being a multi-component distillation system, it is not simple to
operate. The difficulties encountered include the decay heat of
tritium (associated with the decay of tritium into helium-3),
which would evaporate all the liquid. The pressure drop is
minimized, however, and temperature variations are kept to a
minimum.
Scientists from the group say the philosophy of the plant's
operation is based on fail-safe conditions. The operation of the
entire distillation column takes place at atmospheric pressure
and an ambulant temperature of -268 0C. The whole plant has two
sections: a low tritium activity section and a high tritium
activity section (see graphic). The scientists involved say that
nearly 240 stages are involved in the tritium enrichment process,
and so it has to be carried out in three-stage cascade
distillation units. The deuterium-tritium gas, which emerges from
the second stage, is 100 per cent enriched. After this the
tritium is separated suing an equilibrator, with the condensed
product serving as the reflex for the third stage. The highly
concentrated tritium is drawn off periodically from the bottom of
the cryogenic column and immobilized in a matrix of metal
tritride, which would be compact, safe and stable at normal
temperature. The gas can be recovered at any time by heating the
metal tritride. At this stage the pure tritium is ready for
stockpiling.
[Next : Why the US missed India's nuclear tests?]
