Proper prediction of the pressure swing to be expected in PWR transient requires accurate calculation of the pressurizer surge line flow. A detailed surge line thermal-hydraulic analysis algorithm is developed, which uses the EICE method. The EICE method consists of a two-step iteration technique which results in a solution of the fully coupled conservation equations.
The developed surge line algorithm is examined against RELAP5/MOD2 code to verify its correctness. The calculated surge flow rate by the surge line algorithm is in good agreement with the calculated value obtained by RELAP5/MOD2 cede.
The system code, NLOOP is modified to couple the surge line algorithm with the NLOOP code calculation scheme. Test calculations show that the pressure swing phenomena during sudden power changes is well predicted by the developed surge line algorithm.
