Novel burnup measurement system via anti-compton techniques for HTR-10

Abstract

To enhance the spectrum quality and allow additional data mining for burnup correction in complex reactor operation history and nuclear material accountancy, a novel burnup measurement system based on anti-compton techniques was created, installed, and tested in the HTR-10 system. The novel burnup measurement system suppressed the compton plateau by a factor of greater than 5 in case of end-cap incidence that did increase the pulse-to-compton ratio from 101 to 532 by single channel spectrometer scheme and from about 103 to 577 by dual channel spectrometer scheme for 661.7 keV of radioactive source of Cs-137. When standard calibration and its extension were finished, the new BUMS were operated for several months with HTR-10 since the second half of 2020. Three irradiated fuel pebbles were discharged out for offline measurement including radiochemical analysis for validation. The result presents very good agreement on measured Cs-137 activity with relative error ranging from around −4.3% to −1.4% when comparing corresponding results of online burnup assay by anti-compton BUMS to post irradiated examination by radiochemical analysis. Activities of isotopes were estimated meanwhile to support burnup correction and achieved preliminary satisfying result.