Purnima I-II-III

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Last Updated: September 1, 2003
Other Name: Plutonium Reactor for Neutronic Investigation in Multiplying Assemblies
Location: Trombay, Mumbai
Subordinate To: Nuclear: Research Reactors
Size: Large-scale, output 100-150 tons per year (t/y)
Facility Status: Operational

The Purnima reactor is a series of critical assemblies built to study neutron behavior in fission and the use of U-233 as a fuel. The Atomic Energy Commission approved the Purnima project in 1969. Construction began in 1970 and Purnima-I obtained criticality on the 18 May 1972. This small, tank-type, fast neutron reactor used 21.6kg of Pu-239 in the form of plutonium-oxide pellets to produce a nominal power output of 1 watt. As a pulsed fast reactor, Purnima-I operated on much the same principles as a rudimentary fission bomb. This gave BARC scientists benchmark calculations on the behavior of a chain-reacting plutonium system and the kinetic behavior of the system just above criticality. These calculations were used to determine the optimum explosive power and the neutron trigger of future bombs. Purnima-I operated until 1974 when it was decommissioned and renovated to produce Purnima-II, a homogenous tank-type critical assembly. This critical assembly burned a 400 gram, uranium-233-nitrate solution as fuel, producing a nominal power of 10 watts. Purnima-II first reached criticality on 10 May 1984. The critical assembly was used to study the use of U-233 as a fuel for future reactor designs. It was decommissioned and renovated to produce Purnima-III, which first obtained criticality on 9 November 1990. The critical assembly is fuelled by uranium-233 plates clad in aluminum weighing a total of 600 grams. It produced a maximum power output of 1 watt. Light water served as the coolant and moderator while the control rods consisted of cadmium. Purnima-III was used as a mockup for the Kamini reactor at the Indira Gandhi Center for Atomic Research (IGCAR).

[1] Andrew Koch, "Selected Indian Nuclear Facilities," Center for Nonproliferation Studies (CNS), 1999, www.nonproliferation.org.
[2] Bhabha Atomic Research Center (BARC), www.barc.ernet.in.
[3] George Perkovich, India's Nuclear Bomb: the impact on Global Proliferation (Berkeley, CA: University of California Press, 1999), pp. 149-150.
[4] 2000 World Nuclear Industry Handbook (Wilmington, UK: Nuclear Engineering International, 2000), p. 198.

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