Radiation-induced thermoelectric sensitivity (RITES) in ITER prototype magnetic sensors

Abstract

This report summarizes the results of in situ measurements of noninductive voltages developed across prototype International Thermonuclear Experimental Reactor (ITER) magnetic coils performed at the Japan Materials Test Reactor. The voltages appear to be mainly thermoelectric in origin, with the thermal sensitivity developing gradually through irradiation and the thermal gradients supplied by nuclear heating. Possible mechanisms and circuits within the coils that can contribute to this radiation-induced thermoelectric sensitivity are described, and schemes to improve the ITER coil design are outlined.

Radiation Effects on the Components of Diagnostic Systems for a Thermonuclear Reactor: A Review

“…It has been suggested that this cable be used as a thermocouple, the thermal emf of which sharply increases under irradiation. This effect is now known as radiation-induced thermoelectric sensitivity (RITS) [39,40]. It is thought that the thermal emf can be reduced significantly by properly selecting the conductor material; e.g., copper must be excluded wherever possible [39,40].…”

“…This effect is now known as radiation-induced thermoelectric sensitivity (RITS) [39,40]. It is thought that the thermal emf can be reduced significantly by properly selecting the conductor material; e.g., copper must be excluded wherever possible [39,40]. Generally speaking, since β-active elements are produced by neutron irradiation of copper and aluminum, these metals should not be used as construction materials [14,41].…”

The magnetic diagnostic set for ITER

“…In addition to this, nucleartransmutation products can lead to a significant thermally induced EMF at the integrator input during the pulses for invessel sensors, causing again a cumulative error in the integrator output baseline [27]. As compensation is currently not foreseen, mitigation of this source of error is only based on thermal-gradient reduction in the sensors and cables and on high signal amplitudes and material choice.…”

Neutronics analysis for ITER cable looms

“…The temperature gradients together with the nuclear transmutation of the cable's copper could result in formation of thermocouples and hence non-inductive parasitic voltages due the Radiation-Induced Thermoelectric Sensitivity (RITES) effect [2].…”