Reactors, Reprocessing & Centrifuges: India’s Enduring Embrace of Fissile Material

India has traditionally relied on plutonium for developing nuclear weapons – which was used in its Pokhran-I 1974 test and in the Pokhran-II tests conducted in May 1998. It also claimed to have tested a hydrogen bomb in May 1998 for which Highly Enriched Uranium was most likely used as a trigger spark plug in the secondary stage of the thermonuclear device. India has continued efforts to acquire the technology for developing and sustaining a gas-centrifuge program for uranium enrichment in parallel with a fissile material/nuclear fuel cycle production infrastructure for producing plutonium.

India’s interest in gas-centrifuge technology for enriching natural uranium is four decades old. Curiously enough, this coincided with Pakistan’s own quest for centrifuges. India began initial Research and Development (R&D) work on centrifuges at the Bhabha Atomic Research Center (BARC) as early as 1972. The experimental centrifuge program’s first milestone was achieved in 1986 with the installation of the first cascade consisting of about 100 machines that was able to produce 2% enriched uranium. The same year, India’s Department of Atomic Energy (DAE) began construction of a larger centrifuge enrichment facility—the Rare Materials Plant—at Rattelhali, Mysore which was commissioned around 1990. Although it was originally designed to house 5000 centrifuges, India was only able to achieve a breakthrough in 1997 with the development of super-critical centrifuges, but the desired number of machines could not be built. Ten years later, RMP still had only about 3000 centrifuges (15000 SWU) in two or three cascades. For two decades, India was only able to develop sub-critical centrifuge machines from domestically produced maraging steel that were inefficient and fraught with technical issues and suffered frequent break-downs. These were most likely derivatives of the 1950-60s era Zippe-type centrifuge machines whose design was publicly known, while the DAE may have substituted aluminum rotors with maraging steel to achieve greater rotating velocities. The then-Chairman of India’s Atomic Energy Commission, P. K. Iyengar acknowledged in a March 1992 interview that while India had succeeded in producing highly enriched uranium, the country’s centrifuge program was still facing technical difficulties. The same year, Raja Ramanna, former Chairman of India’s AEC also admitted that India was working on more efficient and super-critical centrifuges.

India managed to achieve great strides in centrifuge design and development in the past 20 years, especially since 1997 when it began producing super-critical gas-centrifuges—similar to URENCO and Pakistani designs. Interestingly, India’s centrifuge technology is predominantly based on maraging steel rotor and carbon-fiber rotor assemblies. The design installed in the largest number of cascades at RMP consists of two thin-walled centrifuge rotors made from 350-grade maraging steel with one bellow in the middle and an outer rotor diameter of 150 mm. This corresponds exactly to the URENCO G-2 and the Pakistani P-2 centrifuge designs (this merits an altogether separate discussion). More advanced Indian centrifuge designs are also close derivatives of URENCO machines including those made from maraging steel and the latest generation machines with carbon-fiber rotor assemblies.

Source: Zia Mian, “India developing new centrifuges and increasing enrichment capacity,” International Panel on Fissile Materials Blog, June 4, 2010.

The timelines of India’s development of super-critical or ultra-centrifuge technology matches that of Iran and North Korea and most of the critical breakthroughs occurred at around the same time when these countries were actively engaged in acquiring centrifuge design information, prototypes and materials from the illicit nuclear black market. India’s centrifuge program was also heavily dependent on illicit nuclear trade throughout the 1980s and 90s. It was openly inviting bids as late as 2005 for high-strength flow-formed maraging steel tubes for manufacturing centrifuge rotors; machining of bellows for centrifuge rotors; maraging steel discs used in centrifuge end caps; subcomponents of centrifuge bottom bearings and motor stators; displacement sensors for measuring centrifuge rotor velocity; vacuum pumping and measurement systems, specialized valves, and subcomponents of valves and vacuum pumping systems; electron beam welding and three roller, four axis CNC flow forming machines; pressure transducers and CNC machines that Iran (transducers) and North Korea (CNC machines) have either attempted to or succeeded in procuring and employing for their centrifuge development programs. Therefore, it is highly unlikely that India would have succeeded in achieving breakthroughs in ultracentrifuge technology without having access to design information, materials, machines and know-how related to URENCO and G-2/P-2 machines through the illicit nuclear black market of centrifuge technology that spanned several countries.

India’s Expanded Centrifuge Enrichment Plant at Rattehali, 2014

India’s recent expansion in its uranium enrichment program (from 30-45000 SWU to 126,000 SWU), comprising a second uranium hexafluoride production (UF-6) and another gas-centrifuge plant to fuel its submarine reactors and nuclear and weapons at the RMP site is scheduled to be completed by 2015. According to a 2011 statement by Srikumar Banerjee, Chairman of India’s Atomic Energy Commission, a new “industrial-scale” Special Material Enrichment Facility was being established at Chitradurga district, Karnatka, to produce 1.1 percent enriched fuel for increasing the burn-up of India’s PHWRs from 7000 to 20,000 MWd/t, thus increasing their fuel efficiency. But he added that the new centrifuge plant would not be placed under safeguards and its military use option was being kept open, just as India’s 500 MW EFBR program was kept on the military list under the separation plan of the Indo-US deal. Banerjee added that India’s existing uranium enrichment capacity was sufficient to meet all fuel requirements for the country’s nuclear submarine fleet.  This endorses the fact that any additional enrichment potential at RMP is geared toward the production of weapon-grade HEU for India’s nuclear weapons program. The excess enrichment capacity of 103,250 SWU is sufficient for producing HEU for at least 21 first-generation solid-core HEU (implosion-based) weapons. The same HEU can be used along with abundant military plutonium stockpiles for creating composite/hybrid fissile cores for India’s fission, boosted fission and thermonuclear weapons. These would enable the development of a large triad-based nuclear arsenal consisting of several hundred (400-600) warheads that would be deployed on India’s single and multiple warhead missile systems (including ICBM and SLBMs). India has deliberately kept its fissile material production facilities outside safeguards in order to keep the option open for to meet the anticipated requirements of a large nuclear arsenal as stated by the DAE Chairman Anil Kakodkar: “Both from the point of view of maintaining long term energy security and for maintaining the minimum credible deterrent the Fast Breeder Program just cannot be put on the civilian list.”

India’s Unsafeguarded Fissile Material Production Infrastructure

Sources: International Panel on Fissile Materials; International Panel on Fissile Materials; IHS Jane’s

PHWR: Pressurized Heavy Water Reactor

EFBR: Experimental Fast Breeder Reactor

WG Pu: Weapon Grade Plutonium

RG Pu: Reactor Grade Plutonium

tHM/yr: tons of heavy metal/year

SWU: Separative Work Unit. Almost 5000 SWU are needed to produce 25 kg or “One Significant Quantity” of weapon-grade HEU for one device.

HEU: Highly Enriched Uranium

India already enjoys a huge advantage in existing stockpiles over Pakistan with a 2013 stockpile of 2.4 ± 0.9 tons of HEU (30-40 enriched=800 kg weapon-grade HEU); 750 kg of weapon-grade plutonium and 5.0 tons of weapon-usable reactor-grade plutonium produced by India’s Pressurized Heavy Water Reactors. This stockpile of reactor-grade plutonium has been designated as “strategic” and would therefore remain outside safeguards. These fissile material holdings are currently sufficient for producing 187 warheads from WG Pu @ 4 kg/warhead; 32 warheads from WG HEU @ 25 kg/warhead; 625 to 1875 warheads from Reactor-Grade Pu @ 8 kg/warhead. The existing reservoir of fissile material will continue to be increased through additional production and very large reprocessing facilities that are nearing completion and are in the pipeline (EFBR and Dhruva-2) in the next five years along with “the planned integrated nuclear [reprocessing] plant for handling close to 500 tonne/year of heavy metal” at Tarapur (There are three functioning 100 tHM/yr reprocessing plants at Kalpakkam).

India’s expansion in fissile material production infrastructure, particularly its uranium enrichment program using gas-centrifuge technology, has been greatly facilitated with the availability of the country’s entire domestic uranium ore deposits and reserves for the nuclear weapons program. The expansion at the RMP facility began when the Indo-US nuclear deal was being finalized which helped India to meet all nuclear fuel requirements for its nuclear energy program. Earlier, India’s indigenous nuclear power reactors were also a major consumer for India’s limited domestic uranium ore production along with the fissile material production for the nuclear weapons program. However, this is not to suggest that India’s entire stockpile of fissile material has been weaponized, but the potential of tapping this huge advantage will remain ever present and would be factored in by Pakistan in determining its credible minimum deterrence posture requirements (without getting into a Cold War style nuclear arms race).

Pakistan has not been participating in the FMCT negotiations at the Conference on Disarmament in Geneva and is accused of being the sole outlier state whose principled stand rests on the demand of addressing existing asymmetries (that favors all other nuclear weapon states including India) as well as stopping future production of fissile material stockpiles. However, for taking the entire flak for blocking progress on the FMCT, Pakistan has attracted criticism which has, simultaneously served to divert attention from India’s steady expansion in fissile material production capabilities (both in plutonium and highly enriched uranium). In view of India’s unprecedented and exponential increase in fissile material production capacity outside any of the NPT nuclear weapon states—a singular distinction that should earn it the title of having the world’s fastest growing nuclear arsenal—it might be prudent for Pakistan to consider linking participation in negotiations at the CD on the FMCT (and/or eventual signing of the treaty) with India’s simultaneous concurrence to the FMCT. This would help in promoting a non-discriminatory and relatively equitable global nuclear non-proliferation regime rather than one based on the tenets of neo-nuclear apartheid.

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Image: IHS Jane’s Intelligence Review