Change in radiation characteristics outside the SNF storage container as an indicator of fuel rod cladding destruction

• Published in: Nuclear engineering and technology Vol. 53; no. 11; pp. 3704 - 3710
• Main Authors: Rudychev, V.G., Azarenkov, N.A., Girka, I.O., Rudychev, Y.V.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01-11-2021; Elsevier; 한국원자력학회
• Subjects: Dry cask storage; Fuel rod claddings; Storage container; 원자력공학; Dry cask storage; Storage container; Fuel rod claddings
• ISSN: 1738-5733; 2234-358X
• DOI: 10.1016/j.net.2021.05.029

The characteristics of the external radiation on the surface of the casks for spent nuclear fuel (SNF) storage by dry method are investigated for the case when the spatial distribution of SNF in the basket changes due to the destruction of the fuel rod claddings. The surface areas are determined, where the changes in fluxes of neutrons, produced by 244Cm actinide, and γ-quanta, produced by long-lived isotopes, are maximum in the result of the decrease in the height of the SNF area. Concrete (VSC-24) and metal (SC-21) casks are considered as examples. The procedure of periodic measurement of the dose rate of neutrons or γ-quanta at the specified points of the cask surface is proposed for identifying the fuel rod cladding destruction. Under normal operation, the decrease in the dose rate produced by neutrons as the function of SNF storage duration is determined by the half-life of 244Cm, and for γ-quanta - by the half-lives of long-lived SNF isotopes. Consequently, a stepwise change in the dose rate of neutrons or γ-quanta, detected by the measurements, as compared to the previous one, would indicate the destruction of the fuel rod claddings.