A Comparison of RELAP5/MOD2 Results to the Data of a Small-Break Loss-of-Coolant Accident Experiment of an IAEA Standard Problem Exercise

The results generated from the IBM version of RELAP5/MOD2 are compared with the experimental data of an International Atomic Energy Agency standard problem exercise. The standard problem exercise data were that of a 7.4% break loss-of-coolant accident conducted at a test facility in Hungary. The United States did not formally participate in this exercise, whose aim was to assess the capabilities of computer codes and modeling techniques and in which a total of 17 organizations from 12 countries participated. The results obtained by execution of RELAP5/MOD2 on the IBM-3090 computer for upper plenum pressure, core inlet and outlet coolant temperature, and secondary-side pressure differed slightly during the latter part of the transient, but in general compared favorably to the experimental data. The magnitude of the cold-leg mass flow rate was underpredicted by the code.