Creep test for FBR fuel cladding tubes (XVIII)D

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PNC TJ9502 89-001, 100 Pages, 1989/03

PNC-TJ9502-89-001.pdf:2.3MB

Cladding tubes of advanced austenitic stainless steel with more superior creep strength and void swelling resistance than the modified 316 stainless steel are being developed in Power Reactor and Nuclear Fuel Development Corporation. In National Research Institute for Metals, a part of internal-pressurized creep test is conducted as a member of Creep-subgroup in PNC in order to evaluate a creep properties of developed cladding tubes under internal pressure. In the present 18th program, creep rupture tests under internal pressure at 750C and interrupted creep tests under internal pressure at 700C were carried out for two kinds of cladding tubes of advanced austenitic stainless steel which had been domestically trial-manufactured in fiscal year 1987. Two kinds of cladding tubes in this test, 62AS and 62AK, have the same main chemical composition, 15Cr-20Ni-2.5Mo-0.25Ti-0.1Nb, as the cladding tubes examined in the 13th, 14th and 16th programs. Creep rupture strength under internal pressure of 62AK was higher for shorter rupture times than that of 62AS, but for longer rupture time, creep rupture strength of 62AK was nearly equal to that of 62AS. 62AS in this study showed the higher creep rupture strength than 60AS which was trial-manufactured in fiscal year 1985. It was considered that more superior creep rupture strength of the cladding tubes for this study was due to higher temperature solution heat treatment enough to dissolve Nb and higher cold-working. The size of cladding tube (outside diameter and thickness) trial-manufactured in fiscal year 1987 is different from that of fiscal year 1985 cladding tube, but the effect of cladding tube size on creep rupture strength was not recognized. The interrupted creep tests of 62AS and 62AK were conducted under hoop stress of 100 and 81MPa at 700C, and the creep deformation data of cladding tubes were measured. Swelling of tube for 62AS showed transient and steady regions like an ordinary ...