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Russia withdraws from 25-year-old weapons-grade plutonium agreement
Russia’s lower house of Parliament, the State Duma, approved a measure to withdraw from a 25-year-old agreement with the United States to cut back on the leftover plutonium from Cold War–era nuclear weapons.
Om Prakash Joneja, Vijay R. Nargundkar
Fusion Science and Technology | Volume 18 | Number 2 | September 1990 | Pages 310-316
Technical Paper | Blanket Engineering | doi.org/10.13182/FST90-A29302
Articles are hosted by Taylor and Francis Online.
Monte Carlo calculations are performed for a full-coverage spherical system consisting of a stainless steel first wall and a lead-beryllium neutron multiplier. All the calculations use the MORSE-CG code, employing the Los Alamos National Laboratory 30-group neutron cross-section set CLAW-IV in P3 approximation. For multiplier thicknesses varying from 3 to 22.5 cm, the ratio of neutrons leaking from the system with and without 1.5-cm-thick stainless steel decreases from 1.48 to 1.41 for lead and from 1.78 to 1.58 for beryllium. For a three-region system consisting of a first wall, multiplier, and a homogeneous mixture of water and natural lithium, the tritium breeding ratio for the stainless steel-beryllium-homogeneous (natural lithium + water) system is only ∼9% more than that of the stainless steel-lead-homogeneous (natural lithium + water) system. Recent measurements and calculations on neutron multiplication suggest a downward correction for Be(n,2n) and an upward correction for Pb(n,2n) in the ENDF/B-IV cross-section set. In light of such changes in cross sections, a comparison is made between beryllium and lead as a multiplier with a stainless steel first wall.