Mechanical integrity of floor liner in secondary heat transport system cells of Monju

; ; Ueno, Fumiyoshi; ; ; ;

JNC TN2400 2000-005, 103 Pages, 2000/12

JNC-TN2400-2000-005.pdf:3.98MB

Inelastic analyses of the floor liner subjected to thermal loading due to sodium leakage and combustion were carried out, considering thinning of the liner plate due to molten salt type corrosion. Because the inelastic strain obtained by the analyses stayed below the ductility limit of the material, mechanical integrity, i.e., there exist no through-wall crack on the floor liner, was confirmed. Partial structural model tests were conducted, with a band of local thinning of the liner plate. Displacements were controlled to give specimens much larger strains than those obtained by the inelastic analyses above. No through-wall crack was observed by these tests. Mechanical integrity of the floor liner was confirmed by these results of the inelastic analyses and the partial structural model tests.

Effects of neutron flux and temperature history at the beginning of irradiation on the mechanical properties of austenitic stainless steel irradiated with neutrons

Kasahara, Shigeki; Chimi, Yasuhiro; Nishiyama, Yutaka; Kitsunai, Yuji*; Chatani, Kazuhiro*; Koshiishi, Masato*

no journal, , 

Austenitic stainless steel irradiated with neutrons by using JMTR were examined to evaluate the effects of neutron flux and temperature history at the beginning of the irradiation on their mechanical properties. Specimens of SUS304 were irradiated under two different flux conditions up to a dose of 510 n/m. Neutron irradiation of SUS316L specimens up to 210n/m was performed under the condition of so-called conventional temperature control, which used to be adopted in JMTR. The comparison of 0.2% proof stress obtained from the specimens suggests that the neutron flux and the temperature history does not remarkably influence the mechanical properties of the irradiated stainless steel.

Influence of temperature histories during reactor startup periods on IASCC susceptibility of austenitic stainless steel irradiated with neutrons

Kasahara, Shigeki; Chimi, Yasuhiro; Kitsunai, Yuji*; Koshiishi, Masato*

no journal, , 

According to existing data of slow strain rate tensile (SSRT) test under high temperature water conditions, which simulated BWR primary coolant environment, low carbon stainless steel, which was irradiated with neutrons up to about 3 dpa in BWR core, shows susceptibility of Irradiation associated stress corrosion cracking (IASCC). On the other hand, the stainless steel irradiated by using the JMTR did not show IASCC susceptibility, regardless of neutron fluence. To investigate this different result about IASCC susceptibility, the JMTR operated to simulate temperature history at start-up of BWR, and a tensile specimen of SUS316L was irradiated up to about 3 dpa under the condition. After that, the specimen was examined by SSRT test to evaluate IASCC susceptibility. The result of fracture surface observation after the SSRT test indicated that the specimen fractured by Inter-granular mode and was evaluated to be susceptible to IASCC. In the comparison of the data of IASCC sensitivity by the JMTR irradiated materials, which did not show IASCC susceptibility, the difference of them was suggested to attribute to different temperature histories at the start of irradiation. The relationship between IASCC susceptibility and the parameters obtained from tensile tests was discussed, in consideration of the difference of the tensile parameters which are suffered from the irradiation condition under the different temperature history during the start period of the irradiation.