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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.
Harald Zänker
Nuclear Technology | Volume 86 | Number 3 | September 1989 | Pages 239-247
Technical Paper | Fission Reactor | doi.org/10.13182/NT89-A34292
Articles are hosted by Taylor and Francis Online.
Periods of continuously decreasing levels of fuel rod integrity due to debris-induced cladding damage, vibration-induced fretting wear of the cladding, etc., cause difficulties in the assessment of fuel rod performance from coolant activity data. The calculational models currently in use for this purpose in nuclear power plants are not sufficiently capable of indicating cases in which they are invalid. This can mislead reactor operators by misinterpretation of the coolant activity data, especially in situations where fast reactions are necessary. A quick test of validity is suggested to check the applicability of the currently available calculational models for estimating the number and average size of fuel rod defects. The criteria of applicability are the fission product total activity, the slope tanα in the relationship Ig(Ri/Bi) = tanαlg λi for the volatile fission product isotopes, and the activity of nonvolatile nuclides such as 239Np and the isotopes of ruthenium and cerium. The objective is to recognize immediately periods of continuously decreasing levels of fuel rod integrity in order to prevent complications in routine power plant maintenance as well as accident situations caused by more severe fuel rod degradation.
