Nuclear study provides major update on plutonium isotope fission
- June 24, 2024
- Posted by: OptimizeIAS Team
- Category: DPN Topics
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Nuclear study provides major update on plutonium isotope fission
Sub: Science and tech
Sec: Nuclear Energy
Context:
- On March 4, India advanced to the second stage of its nuclear power programme by starting core-loading of the prototype fast breeder reactor (PFBR) at Madras Atomic Power Station, Kalpakkam.
Details:
- The first stage used uranium isotopes in heavy-water reactors to produce plutonium-239 (Pu-239) and energy.
- The second stage focuses on plutonium fission, with Pu-239 capturing neutrons and becoming Pu-240 or undergoing fission.
Understanding Pu-240 Fission:
- When Pu-240 captures a neutron, it can turn into Pu-241 or undergo fission, but predicting the energy of fission products is complex.
- The prompt fission neutron spectrum (PFNS) measures neutrons emitted immediately after neutron capture by Pu-240.
- Only two studies have measured PFNS in Pu-240; the latest used higher-energy neutrons and found significant deviations from theoretical predictions.
Implications and Uses of New Findings:
- The PFBR uses plutonium from the CANDU reactor spent fuel, which contains Pu-240, making new data on Pu-240 behaviour relevant.
- Pu-240, considered a contaminant in weapons-grade plutonium, is harder to separate from Pu-239 and accumulates predictably.
- The recent study by researchers at Los Alamos Neutron Science Centre used a pure Pu-240 sample to measure neutron energies and fission products, identifying higher-than-expected second-chance fission rates.
- So far there has only been one study that attempted to study the PFNS of induced fission in Pu-240, where neutrons that bombarded the Pu-240 nuclei had an energy of 0.85 mega-electron-volt (MeV).
Impact on Nuclear Data Libraries:
- Discrepancies between predicted and observed PFNS data suggest updates are needed in nuclear data libraries like ENDF, JEFF-3.3, and JENDL-5.0.
- These libraries are crucial for reactor design, radiation shielding, nuclear medicine, and other applications.
- The study found that only JENDL-5.0 included both multi-chance fission and pre-equilibrium neutron emission processes, highlighting areas for improvement in other libraries.
Important terms:
Prototype fast breeder reactor (PFBR) |
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Pressurised Heavy Water Reactor (PHWR) |
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CANDU Reactors |
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Source: TH