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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.
Atul A. Karve, Chae Han, Rizwan-uddin
Nuclear Technology | Volume 123 | Number 2 | August 1998 | Pages 121-129
Technical Paper | Fission Reactors | doi.org/10.13182/NT98-A2886
Articles are hosted by Taylor and Francis Online.
Axial power shapes that develop during power-maneuvering simulations in pressurized water reactors must be analyzed to ensure that an adequate margin to avoid departure from nucleate boiling (DNB) is maintained during these transients. To reduce the number of flux shapes that need to be analyzed in detail to determine the DNB ratio (DNBR), often generic axial flux shapes are analyzed and maximum-allowable-peaking (MAP) limits are determined to conservatively filter those actual axial power shapes that are clearly safe. Current generic MAP limits, obtained for axial flux shapes generated by a two-parameter-based axial flux shape generator, are overly conservative for some power shapes and are nonconservative for others, leading to unnecessary operational restrictions on conservative cases. A penalty is imposed on nonconservative cases. To reduce the number of overly conservative and nonconservative cases, a new generic axial power shape generator that is based on three parameters is developed. Generic MAP limits have been developed for the new axial flux shape generator and tested using real flux shapes by plotting the percent deviation of MAP limits for generic flux shapes from the corresponding value for actual flux shapes. A new axial flux shape generator, which is clearly superior because it leads to a significantly lower percent deviation, will lead to reduced man-hours for detailed DNBR analyses and remove some of the unnecessary operational restrictions imposed by the old flux shape generator.