SIMMER-III analysis of CAMEL C6, C7 tests.

摘要

To mitigate or eliminate the recriticality concern during core disruptive accidents of liquid-metal fast reactors (LMFRs), it is very effective to demonstrate that a large amount of molten fuel can be removed sufficiently early from the active core region through control rod guide tubes (CRGTs). The SIMMER-III computer code has been developed as an advanced safety analysis tool of LMFRs at the Japan Nuclear Cycle Development Institute (JNC). The validation of this code is also being conducted for key physical phenomena relevant to accident sequences including fuel removal. In the present study, an analysis of the CAMEL C6 and C7 tests, which simulated the fuel escape through the CRGT channel, has been performed. Main conclusions from the present analysis are as follows: (1) SIMMER-III can reasonably simulate the pressurization due to fuel- coolant interaction (FCI) and the void expansion behavior in the CRGT; (2) It was confirmed that the large mass of molten fuel was discharged into the voided duct after the initial pressurization by FCI occurred and the void region developed in the channel; and (3) Although the prototypicality of the CAMEL tests is poor in terms of fuel mass, we have demonstrated that SIMMER-III can well reproduce the initial FCI behavior where only a small amount of molten fuel is actually involved even under the reactor condition. This result is encouraging to support the applicability of SIMMER-III to the CRGT fuel removal analysis in LMFRs. (author)