Evolution of thermo-physical properties and annealing of fast neutron irradiated boron carbide

JOURNAL OF NUCLEAR MATERIALS

卷:500

Article

Gosset, Dominique¹  Bonal, Jean-Pierre²  Verdeau, Caroline³  Froment, Karine⁴ 

[1] Univ Paris Saclay, CEA, DEN, Serv Rech Met Appl, F-91191 Gif Sur Yvette, France

[2] CEA Paris Saclay, DEN, DDCC, UADF,CCOD, Site Fontenay Aux Roses, F-92260 Fontenay Aux Roses, France

[3] CEA Cadarache, DEN, CAD, DTN, F-13115 St Paul Les Durance, France

[4] CEA Grenoble, Arc Nucleart, DRT, LITEN,ARCNUC, F-38054 Grenoble, France

关键词: Boron carbide;    Neutron absorber;    Thermal conductivity;    Microstructure;    Heat treatments;   

DOI  :  10.1016/j.jnucmat.2017.11.027

来源: Elsevier

【 摘 要 】

Boron carbide is widely used as a neutron absorber in most nuclear reactors, in particular in fast neutron ones. The irradiation leads to a large helium production (up to 10(22)/cm(3)) together with a strong decrease of the thermal conductivity. In this paper, we have performed thermal diffusivity measurements and Xray diffraction analyses on boron carbide samples coming from control rods of the French Phenix LMFBR reactor. The burnups range from 10(21) to 8.10(21)/cm(3). We first confirm the strong decrease of the thermal conductivity at the low burnup, together with high microstructural modifications: swelling, large microstrains, high defects density, and disordered-like material conductivity. We observe the microstructural parameters are highly anisotropic, with high micro-strains and flattened coherent diffracting domains along the (001) direction of the hexagonal structure. Performing heat treatments up to high temperature (2200 degrees C) allows us to observe the material thermal conductivity and microstructure restoration. It then appears the thermal conductivity healing is correlated to the micro-strain relaxation. We then assume the defects responsible for most of the damage are the helium bubbles and the associated stress fields. (c) 2017 Elsevier B.V. All rights reserved.

【 授权许可】

Free