Characterisation of RBMK-1500 graphite: A method to identify the neutron activation and surface contamination terms

• Published in: Nuclear engineering and design Vol. 361; p. 110501
• Main Authors: Remeikis, V., Plukienė, R., Plukis, A., Barkauskas, V., Gudelis, A., Druteikienė, R., Gvozdaitė, R., Juodis, L., Duškesas, G., Lagzdina, E., Germanas, D., Ridikas, D., Krutovcov, S.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 01.05.2020; Elsevier BV
• Subjects: Actinides; Activation; Cesium 134; Cesium 137; Cesium isotopes; Cesium radioisotopes; Computer simulation; Contamination; Destructive testing; Gamma rays; Graphite; Impurities; Irradiated graphite; Modelling; Neutrons; Nuclear spectrometry; Nuclides; Pollution sources; Radioisotopes; RBMK; RBMK-1500 reactor; Reactors; SCALE 6.2 modeling; Spectrometry; RBMK-1500 reactor; SCALE 6.2 modeling; Irradiated graphite; Nuclear spectrometry
• ISSN: 0029-5493; 1872-759X
• DOI: 10.1016/j.nucengdes.2019.110501

•Spent graphite characterization using modelling and nuclear spectrometry.•Method for neutron activation and surface contamination terms identification.•Ignalina NPP Unit I graphite model validation by nuclear spectrometry measurement.•SCALE 6.2 code use for neutron activation calculation of RBMK reactor graphite.•Important results for decommissioning process of the RBMK type reactors. In this study, we provide the results of radiological characterization of the RBMK-1500 graphite using modeling and nuclear spectrometry; we also introduce a method to identify neutron activation and surface contamination terms for the spent graphite waste. The simplified model of the reactor core created by programme package SCALE 6.2 for 4 × 4 fragment of the core was used for simulation of neutron activation of graphite impurities in the RBMK-1500 reactor. Calculations were supplemented by the non-destructive measurements of gamma-ray emitting nuclides and destructive analysis of selected samples of the graphite stack of Ignalina NPP Unit 1 reactor. Our analysis demonstrates that the partial contribution of different contamination sources can be identified by combining modeling and measurements. The findings on radionuclides such as 14C, 36Cl, 60Co, 134Cs, 137Cs, 154Eu as well as actinides in Ignalina NPP Unit 1 graphite having a significant impact on graphite activity and radiological characterization are discussed. The proposed method is also applicable for identification of contamination source in the other activated components of the reactor core.