Pre-qualification of cladding materials for SCWR fuel qualification testing facility

In frame of the project “HPLWR – Phase 2” (Sept. 2006 to Feb. 2010), prospective cladding materials have been tested up to 650°C and stainless steels, such as 1.4970 which had already been used successfully in sodium cooled fast reactors, turned out to be among the most promising candidates. The main target of the follow-up FP7 project “Fuel Qualification test for SCWR” is to make significant progress towards the design, analysis and licensing of a fuel assembly cooled with supercritical water in a research reactor. The program of dedicated WP4-pre-qualification was focused on evaluation of general corrosion resistance of three austenitic stainless steels 08Cr18Ni10Ti (equivalent of 321), 347H and 316L, which should be pre-qualified for application as a cladding material for fuel qualification tests in SCW conditions. Therefore, the experiments in support of WP4 concentrated on 2000 h corrosion exposures in 25 MPa SCW at two different temperatures 550 and 500oC dosed with 2000 ppb of dissolved oxygen. Coupons manufactured according to ASTM G1-03 with milled surface finish were exposed for 600, 1400 and 2000 h in JRC IET autoclave connected to recirculation loop allowing continual water chemistry control during the test. Following examination of the exposed specimens consisted of weight change calculations and detailed macro and microscopic investigation of oxide layers using SEM, EDX. Furthermore, linear extrapolation to one year of operation in SCW was performed as the most conservative approach. With respect to general corrosion results, all tested steels showed sufficient corrosion resistance in SCW conditions taking into account the conditions foreseen for future fuel qualification test in the research reactor in Rez. When comparing the results of weight change calculations obtained for all three materials, it was found out, that the corrosion resistance increased in the following order: 316L<347 H<08Cr18Ni10Ti.

NOVOTNY Radek;  JANIK Premysl;  NILSSON Karl-Fredrik;  SIEGL J;  HAUSILD P; 

2013-12-11

China Guangdong Nuclear Power Holding Co., Ltd (CGNPC)

JRC86780