There are 96 fuel assemblies m the active core The expected region discharge bum-up is 30000 Mwd/T One fourth of the fuel assemblies are scheduled to be refueled after each 5 winter seasons operation Therefore, the total discharged spent fuel assemblies at the end of lifetime of NHR-200 are only about the amount of another two cores of fuel assemblies It makes possible to storage the whole spent fuel inside the RPV There are m total 200 cells divided mto two layers for spent fuel assembly storage surround the active core A stand-by small pit for defective fuel assemblies is reserved m the reactor building This arrangement makes refueling and spent fuel storage equipment and facilities quite simple In many countnes the concept of spent fuel storage inside RPV is under developing to mcrease the bum-up of fuel For NHR — 200 this arrangement also could mcrease the bum-up about 15%

The accident analysis shows that the design features of NHR-200 provides an excellent safety characteristics not only with a low probability of initiators, but also with a unserious consequences of accidents. The results of LOCA analysis of NHR-200 are listed in Table 2[2],

5. Conclusion

In light of the requirement on safety and economy a NHR should be designed with inherent safe features instead of complex safety systems. An integrated arrangement is one of the key characteristics The experiences gained from NHR-5 four winter seasons operation and the practice of NHR-200 design show that an integrated arrangement with self-pressurized performance, natural circulation and in-vessel spent fuel storage is realistic and has many advantages.

Reference

[1] . Zhang Dafang, Dong Duo etc. " 5 Mw Nuclear Heaung Reactor", Internal Report. (1994. 3).

[2] . LiJincai, Gao Zuymg etc. " Safety Analyses for NHR-200", Internal Report. (1994. 3).

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