Evaluation of initial temperature effect on transient fuel behavior under simulated reactivity-initiated accident conditions

反応度事故条件下の燃料過渡挙動に初期温度が及ぼす影響の評価

杉山 智之 ; 宇田川 豊  ; 更田 豊志

Sugiyama, Tomoyuki; Udagawa, Yutaka; Fuketa, Toyoshi

To evaluate possible effect of initial temperature on the fuel behavior, such as cladding deformation and fission gas release, in a reactivity-initiated accident, two comparative tests were performed on identical high burnup PWR fuel rods at different temperatures in the NSRR. Two tests RH-1 and RH-2 were performed, respectively, at room temperature and 280 C which corresponds to the hot zero power of PWR. The test rods did not fail in the both tests against fuel enthalpy increases of 462 and 378 J/g, respectively. The results of the two tests were consistent to those of previous tests at room temperature, if data were plotted as a function of the peak fuel enthalpy, not of the maximum increase of enthalpy. Computer analysis with the RANNS code confirmed that the cladding residual strain in RH-2 was driven only by the pellet thermal expansion and that the gas-induced strain did not occur because the cladding temperature did not reach high enough to enhance creep deformation.