Experience in estimating neutron poison worths

Conference · Sun Jan 01 04:00:00 EST 1989 · Transactions of the American Nuclear Society; (USA)

OSTI ID:7029565

Chiang, R T; Congdon, S P

Gadolinia, {sup 135}Xe, {sup 149}Sm, control rod, and soluble boron are five neutron poisons that may appear in light water reactor assemblies. Reliable neutron poison worth estimation is useful for evaluating core operating strategies, fuel cycle economics, and reactor safety design. Based on physical presence, neutron poisons can be divided into two categories: local poisons and global poisons. Gadolinia and control rod are local poisons, and {sup 135}Xe, {sup 149}Sm, and soluble boron are global poisons. The first-order perturbation method is commonly used to estimate nuclide worths in fuel assemblies. It is well known, however, that the first-order perturbation method was developed for small perturbations, such as the perturbation due to weak absorbers, and that neutron poisons are not weak absorbers. The authors have developed an improved method to replace the first-order perturbation method, which yields very poor results, for estimating local poison worths. It has also been shown that the first-order perturbation method seems adequate to estimate worths for global poisons caused by flux compensation.

• OSTI ID: 7029565
• Report Number(s): CONF-890604--
• Conference Information: Journal Name: Transactions of the American Nuclear Society; (USA) Journal Volume: 59
• Country of Publication: United States
• Language: English

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NEUTRON ABSORBERS
NUCLEAR POISONS
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WATER COOLED REACTORS
WATER MODERATED REACTORS
XENON 135
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