Nuclear and Physical Properties of Dielectrics under Neutron Irradiation in Fast (BN-600) and Fusion (DEMO-S) Reactors
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ear and Physical Properties of Dielectrics under Neutron Irradiation in Fast (BN-600) and Fusion (DEMO-S) Reactors D. A. Blokhina, *, V. M. Chernova, **, and A. I. Blokhinb, *** a
Bochvar High-Technology Research Institute of Inorganic Materials (АО VNIINM), Moscow, 123098 Russia b Materials Laboratory, Institute of Nuclear Power Engineering, Obninsk, 249190 Russia *e-mail: [email protected] **e-mail: [email protected] ***e-mail: [email protected] Received June 6, 2016
Abstract—Nuclear and physical properties (activation and transmutation of elements) of BN and Al2O3 dielectric materials subjected to neutron irradiation for up to 5 years in Russian fast (BN-600) and fusion (DEMO-S) reactors were calculated using the ACDAM-2.0 software complex for different post-irradiation cooling times (up to 10 years). Analytical relations were derived for the calculated quantities. The results may be used in the analysis of properties of irradiated dielectric materials and may help establish the rules for safe handling of these materials. Keywords: dielectrics, boron nitride, alumina, neutron irradiation, activation, transmutation, gas formation, post-irradiation cooling DOI: 10.1134/S1063778817070031
INTRODUCTION Various dielectrics (Al2O3, MgO, MgAl2O4, BN, Si3N4, SiC, etc.) with melting temperatures ranging from 2000 (silicon nitride) to 3000 K (boron nitride) are used as functional (insulators, disperse reinforcing particles in structural steels and alloys, protective coatings, etc.) and structural composite materials in nuclear and fusion reactors [1–3]. The prospects of using dielectrics (BN, Al2O3, etc.) as irradiation temperature monitors in the process of in-core irradiation of materials were outlined in [3]. It was demonstrated experimentally [3] that single-crystalline alumina (Al2O3) and boron nitride (BN) ceramic make it possible to measure the in-core irradiation temperature in the range of 370–1900 K. The temperature conditions of irradiation are determined by measuring the intensity of optical absorption or the shift of lines in X-ray spectra of irradiated materials as functions of temperature of subsequent post-irradiation annealing. The potential to use dielectric materials as in-core monitors of the irradiation dose in the studies of structure of irradiated dielectrics with high-sensitivity analytical techniques (optical or mass-spectroscopic), where the relative concentrations of isotopes and defects with different isotopic compositions (10В, 11В, 7Li, etc.) are determined, was also demonstrated [3]. The calculation of nuclear and physical properties (activation and transmutation of elements) of dielec-
tric materials irradiated with various neutron spectra in nuclear and fusion reactors is of interest in this context. In the present study, the properties of boron nitride (BN) and alumina (Al2O3) subjected to neutron irradiation in a fast reactor (BN-600) and a fusion reactor (DEMO-S, a project of the National Research Center Kurchatov Institute) [4, 5] are examined. The neutron spectrum of the BN-60
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