Calculations for AP1000 nuclear power plant SGTR accident based on RELAP5/mod 3.3 program
AP1000 nuclear power plant model is founded via RELAP5/mod 3.3 program in detail. Refer to SGTR accident basic assumptions in the safety analysis report, calculations for AP1000 nuclear power plant SGTR accident are carried out. And through comparison between the result got and the result from safety analysis report calculated by LOFTTR2 program, the two results are very consistent. It's found that even if the operators do not interfere, AP1000 nuclear power plant protection systems and passive design measures will trigger an automatic response measures, it can terminate the SG heat transfer tube leaking and make RCS be stable in a safe condition and to prevent SG overflowing and ADS actions occurring.
Frequency and consequences associated with a steam generator tube rupture event
The results of a study into the frequency of steam generator tube rupture (SGTR) events are presented, including estimates on the upper and lower bound frequencies for U-tube and once-through steam generator plants and single- and multiple-tube ruptures. In addition, commercial pressurized water reactor operational data have been researched and iodine spiking data used to develop data bases of maximum resultant iodine concentrations and release rates. The frequencies and iodine spiking magnitudes are compared with other studies, and conclusions are drawn regarding current guidelines for analysis of this design-basis transient.
Thermal-hydraulic response and iodine transport during a steam generator tube rupture
Recent reanalyses of the offsite dose consequences following a steam generator tube rupture have identified a possible non-conservatism in original FSAR analyses. Post-trip uncovery of the top of the steam generator U-tubes, in conjunction with a break near the U-tube top, could lead to increased iodine release due to a reduced ''scrubbing'' of the iodine in the primary break fluid by the steam generator secondary liquid. To evaluate this issue, analyses were performed at the Idaho National Engineering Laboratory. The RELAP5 computer code was used to conduct an analysis of the Surry plant to determine whether the post-trip steam generator secondary mixture level was sufficient to maintain continuous coverage of the U-tubes. The results indicated continuous coverage of the U-tubes. The RELAP5 result was supported by a hand calculation. Additional RELAP5 analyses were conducted to determine magnitudes of iodine release for a steam generator tube rupture. Two sensitivity studies were conducted. The amount of iodine released to the atmosphere was strongly dependent on the assumed value of the partition coefficient. The assumption of steam generator U-tube uncovery, on a collapsed liquid level basis, following reactor trip had a minor effect on the amount of released iodine. 17 refs., 28 figs.,more » 5 tabs.« less