Compton (prompt-response) neutron detectors: Comparison of emitter materials through the nuclear transmutation model

Abstract

Reactors’ safety and efficiency are the determining factors in the modern nuclear power industry, and their required level can be achieved only by using the appropriate control and protection systems. The problem of the accurate and prompt control of energy release is especially important when the reactor is operated near its critical parameters.Currently, β-emission self-powered neutron detectors (SPNDs) are used to control the energy release field in the WWER-1000 core. For such SPNDs, the signal delay and the life-time are inconsistent with the tendency to optimize the reactor operating conditions (for example, with the desire to increase the burnup rate of nuclear fuel). That is why, in order to ensure the necessary safety and economy indicators, it is proposed to use inertialess (prompt-response; Compton) SPNDs in the In-core Instrumentation System. Cd, Co, Er, Hf and Pt are usually used as the neutron-sensitive elements of such detectors. Therefore, it is necessary to determine, based on certain criteria, which metal is the best suited for WWER-1000 conditions. Such studies are usually carried out in real conditions and are quite complex, expensive and require a lot of time. However, the same can be realized by a qualitative comparison, which is a simpler way. In this paper, it is proposed to compare the popular materials of Compton SPNDs through the Rutherford model of nuclear transformations and the ‘Bateman solution’. By considering the calculation results of the elemental composition, the ability to absorb neutrons, the activity, the signal level, and metal cost, the number of possible candidates for the role of the most suitable Compton SPND emitter material can be significantly narrowed down.

Keywords

• Composition calculation
• Bateman equation
• Hafnium detector
• Prompt response
• Nuclear energy
• Burn-up life