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Swiss nuclear power and the case for long-term operation
Designed for 40 years but built to last far longer, Switzerland’s nuclear power plants have all entered long-term operation. Yet age alone says little about safety or performance. Through continuous upgrades, strict regulatory oversight, and extensive aging management, the country’s reactors are being prepared for decades of continued operation, in line with international practice.
Chun-Chang Chao, Chin-Jang Chang
Nuclear Technology | Volume 130 | Number 1 | April 2000 | Pages 27-38
Technical Paper | Thermal Hydraulics | doi.org/10.13182/NT00-A3075
Articles are hosted by Taylor and Francis Online.
The DPRA-SGTR computer program was written to develop a dynamic event tree for the analysis of a steam generator (SG) tube rupture (SGTR) event. Using the dynamic event tree, a full-scope understanding of the possible responses of a plant following an SGTR event and the related actions with the emergency operating procedures (EOPs) can be analyzed. RELAP5/MOD3.2 was linked to DPRA-SGTR to calculate the thermal-hydraulic response of a Westinghouse three-loop pressurized water reactor at the Maanshan nuclear power plant. One SG tube with a double-ended break was postulated at the beginning of the accident. The plant thermal-hydraulic behaviors, status of the mitigation systems, and operator actions following the EOPs were explicitly modeled in the postulated SGTR. A total of 131 sequences were generated after an SGTR event. Among the 131 sequences, 91 sequences with a frequency sum of 8.5 × 10-6 were stopped either because of low-occurrence frequency (<1 × 10-12) or because the preset mission time was reached (30 000 s after initiating the event). Seven out of the 91 sequences with a frequency sum of 6 × 10-9 were intentionally stopped as a fatal error occurred when RELAP5 was calculating the thermal-hydraulic response.