A method for on-line measurement of reactor samarium poison

Abstract

The invention relates to an on-line measurement method for reactor samarium poison. The on-line measurement method comprises the following steps: (a) determining the numerical values of the following nuclear parameters: a <149>Pm fission yield gamma pm, a thermal neutron average microscopic fission cross section sigma f in a reactor, the average nominal flux phi nom of a reactor core, a <149>Pm decay constant lambda pm and the thermal neutron average microcosmic absorption section delta sm of <149>Sm; (b) according to formulas (3) and (5), establishing physical difference models of concentration of the reactors <149>Pm and <149>Sm: Pm(t+delta t)=Pm(t)exp(-lambda pm delta t) + gamma pm sigma f phi / lambda pm(1-exp(-lambda pm delta t)) (3), and Sm(t+delta t)=Sm(t)exp(-delta sm phi delta t) + (exp(-lambda pm delta t)-exp(-delta sm phi delta t)) lambda pm Pm(t) / delta sm phi-lambda pm (5), wherein in the formulas, Pm(t) and Sm(t) are respectively the concentrations of <149>Pm and <149>Sm, and phi (t) is average thermal neutron flux concentration in the reactor at a t moment; (c) monitoring the operation of the reactors in real time, and solving reactivity introduced by samarium at a moment t: Psm(t)=C*delta smSm(t) / v sigma f*10<5>, wherein v is a thermal neutron number averagely generated per fission, and C is a reactivity regulation constant factor. An operator does not need to manually look up a table to calculate the samarium poison, and human error risks are reduced.

Description

technical field [0001] The invention belongs to the field of nuclear reactor engineering, and in particular relates to an online measurement method for reactor samarium toxicity. Background technique [0002] In a thermal neutron reactor, 149 Sm is the second most influential of all fission products 135 An isotope of Xe. For neutrons with an energy of 0.025eV, 149 The absorption cross section of Sm is 40800b. 149 The infinitely diluted resonance integral of Sm is 3400b. 149 The negative reactivity of Sm in the reactor due to the absorption of thermal neutrons is called "samarium poisoning". Samarium poisoning will change with reactor power, fuel consumption and time, and it is particularly important today when nuclear power units need to change power frequently. However, all domestic reactor types of nuclear power units (M310, CPR1000, AP1000, and EPR, etc.) are not equipped with samarium toxicity on-line measurement devices, which cannot display the changes in reactor...

AI Technical Summary

Problems solved by technology

However, all domestic reactor types of nuclear power units (M310, CPR1000, AP1000, and EPR, etc.) are not equipped with samarium toxicity on-line measurement devices, which cannot display the changes in reactor samarium toxicity in real time

Therefore, the current practice is that the operator looks up the charts of the upstream design documents provided by the nuclear designer based on the specific working conditions of the reactor to obtain the "samarium poison" under the corresponding power, fuel consumption and time. This method is relatively subjective and not very Intuitive, especially when the unit needs frequent peak regulation, it greatly increases the workload of the operator and the risk of human error, which is not conducive to the effective maintenance of nuclear safety

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