| 摘要 |
PROBLEM TO BE SOLVED: To conduct the nondestructive measurement of the ratio of fissile Pu to Pu-238 in the quantity of Pu-238 or the Pu composition in highly proliferation-resistant spent fuel. SOLUTION: A gross neutron counting rateϕg and a neutron coincidence rateϕc are determined from a fuel substance. A gross neutron emission rate Sg is found from the gross neutron counting rateϕg, and a coincidence neutron emission rate Sc from the neutron coincidence rateϕc. An overall (α, n) neutron emission rate S<SP>α</SP>is also found. Meanwhile, an estimated value of S<SB>8</SB><SP>α</SP>/S<SP>α</SP>, the ratio of the Pu-238 (α, n) neutron emission rate S<SB>8</SB><SP>α</SP>based on the (α, n) reaction of Pu-238 to the overall (α, n) neutron emission rate S<SP>α</SP>based on the (α, n) reaction of Pu-238, Pu-240, Cm-242, Cm-244 and Am-241, is found by using an estimated value of burnup separately and the Pu-238 (α, n) neutron emission rate S<SB>8</SB><SP>α</SP>is determined by multiplying the estimated value of S<SB>8</SB><SP>α</SP>/S<SP>α</SP>by the overall (α, n) neutron emission rate S<SP>α</SP>to find the concentration of plutonium 238 by using a physical constant of a neutron emission rate. COPYRIGHT: (C)2005,JPO&NCIPI
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