Gamma-beta composite detection device

Abstract

The invention belongs to the technical field of nuclear power maintenance, and particularly relates to a gamma-beta composite detection device. The absorptivity of the first scintillation crystal to beta rays is higher than that to gamma rays so that a first photomultiplier and a first signal processing unit can detect beta rays according to light emitted by the first scintillation crystal; the absorptivity of the second scintillation crystal to beta rays is lower than that of the second scintillation crystal to gamma rays so that a second photomultiplier and a second signal processing unit can detect the gamma rays according to light emitted by the second scintillation crystal, composite detection of the gamma rays and the beta rays is realized, and the damage condition of the fuel assembly at different pile-out time can be judged in an auxiliary manner. Besides, the first scintillation crystal is used as a detection chamber so that the gas to be detected is effectively stored, and the first scintillation crystal can be irradiated by rays released by the gas to be detected more fully from inside to outside, and therefore, the gamma-beta composite detection device can detect beta rays released by the gas to be detected more sensitively.

Description

technical field [0001] The invention belongs to the technical field of nuclear power maintenance, and in particular relates to a γ-β composite detection device. Background technique [0002] The most efficient way to detect nuclear fuel assembly damage is to detect the radioactive fission gas released to the outside. The fissile substances in the fuel assembly mainly include Xe-133, Kr-85, I-131, Cs-136, Cs-134, CS -137 and the isotopes of these elements, among which the gaseous fission products that are not easily soluble in water are mainly Xe-133 and Kr-85 and their isotopes. The gamma-ray decay branch ratio of Xe-133 is large, and the detection of gamma-rays can find obvious energy characteristic peaks, so as to determine Xe-133 and its radioactivity. -133 nuclide to determine the damage. Kr-85 has a long half-life, which can be used as a basis for judging the damage of fuel assemblies for a long time out of the stack. However, the γ-decay branch ratio of Kr-85 is smal...

AI Technical Summary

Problems solved by technology

The gamma-ray decay branch ratio of Xe-133 is large, and the detection of gamma-rays can find obvious energy characteristic peaks, thereby determining Xe-133 and its radioactivity. However, due to the short half-life, it is difficult to measure Xe for fuel assemblies that have been out of the stack for a long time -133 nuclides to determine damage

Kr-85 has a long half-life, which can be used as a basis for judging the damage of fuel assemblies for a long time out of the stack. However, the gamma decay branch ratio of Kr-85 is small, and it is difficult to detect obvious energy characteristic peaks through gamma rays, while beta rays are a continuous spectrum. It is difficult to carry out quantitative and qualitative analysis of radioactive substances when there are many kinds of radioactive substances

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