抄録
For water-cooled ceramic breeder blankets in fusion reactors, neutron multiplier materials such as beryllium are packed into the blankets to obtain tritium breeding capability. Pipe rupture inside the blanket leading to ingress of coolant is an important event to be assessed because the reaction of water or vapor with beryllium is exothermic and produces hydrogen. In order to clarify the safety characteristics related to Ingress of Coolant Event (ICE) in the blanket, the numerical safety analyses have been performed using the modified TRAC-PF1 code based on the two-fluid model. The TRAC-PF1 was modified in the present study to treat a chemical reaction and a heat transfer models inside the packed pebble bed. A Test Blanket Module (TBM) and a cooling system developed for testing in ITER were modeled for the calculation. The coolant conditions were 15.5 MPa of pressure and about 300℃ of temperature. A scenario of the ICE and the loss of flow due to pump trip was analyzed, and the loss of flow scenario without water ingress was also analyzed for comparison. The results showed that the void fraction, the pressure and the liquid temperature in the cooling pipe increased caused by the vaporization of coolant during the ICE. It is also found that the temperature of packed beds rapidly decreased due to the heat removal by contact with the water or vapor. As a result, it is concluded that the modified TRAC-PF1 code is useful as a safety analysis for the ceramic breeder blanket.
