Tham khảo tài liệu 'nuclear power system simulations and operation part 10', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | 124 Nuclear Power - System Simulations and Operation The release of fission products from fuel-clad gap into primary coolant involves clad failure. A model describing pallet oxidation subsequent enhancement of diffusivity and bubble formation at grain boundaries their interlinkage and release into open surfaces was developed by Koo et al 13 . This model is stochastic in nature and incorporates inherent randomness of the underlying physical phenomenon using Monte Carlo method. While the prediction based on this model are in good agreement with the corresponding experimental measurements in the linear heating regime strong under-predictions have been reported for the remaining regime. The Ivanov s model 14 gave good description of various processes involved in the release of FPs from the porous ceramic fuel its leakage from clad and mixing with the primary coolant. Theoretical predictions based on this model have been reported in good agreement with the corresponding experimental data. Combined failures based model has been developed by Clink and Freeburn 15 which was employed in an on-line coolant activity monitoring system. Such systems carryout estimation of failed fuel fractions in non-destructive manner. Normally these systems are designed for constant power steady state operational conditions. The Clinck and Freeburn model was observed to under-predict failed fuel fractions even for steady-state operation 16 . A theoretical model has been developed by Tucker and white 17 for the estimation of FPs from ceramic UO2 fuel. In this model first the probabilities of leakages of FPs from fuel interior through grain-edge tunnel pore to outer portions are figured out. These probabilities strongly depend on the interconnectivity of pores in the ceramic fuel. A good agreement has been reported between theoretical predictions made by using this model and the corresponding experimental measurements. 2. FPA simulation codes In view of the importance of the FPA for normal .
