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Devoted to all aspects of the nuclear fuel cycle including waste management, worldwide. Division specific areas of interest and involvement include uranium conversion and enrichment; fuel fabrication, management (in-core and ex-core) and recycle; transportation; safeguards; high-level, low-level and mixed waste management and disposal; public policy and program management; decontamination and decommissioning environmental restoration; and excess weapons materials disposition.
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ANS Student Conference 2025
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Latest News
First astatine-labeled compound shipped in the U.S.
The Department of Energy’s National Isotope Development Center (NIDC) on March 31 announced the successful long-distance shipment in the United States of a biologically active compound labeled with the medical radioisotope astatine-211 (At-211). Because previous shipments have included only the “bare” isotope, the NIDC has described the development as “unleashing medical innovation.”
Hee-Jin Shim, Chang-Kyun Oh, Hyun-Su Kim, Myung-Hwan Boo, Jong-Jooh Kwon
Nuclear Technology | Volume 190 | Number 1 | April 2015 | Pages 88-96
Technical Paper | Materials for Nuclear Systems | doi.org/10.13182/NT13-150
Articles are hosted by Taylor and Francis Online.
Metal fatigue is a well-known phenomenon whereby material characteristics are deteriorated when even a small load is applied repeatedly. Therefore, an accurate fatigue evaluation is very important in terms of component integrity and reliability. In the design stage, the fatigue evaluation of nuclear class 1 components has to be performed in accordance with Sec. III of the ASME Boiler and Pressure Vessel Code. However, operating experience shows that the design transients are very conservative compared to the actual ones in terms of the heating/cooling rates and the number of transient occurrences. Considering that these two factors affect the thermal stress and thereafter the fatigue usage factor (FUF), the actual fatigue damage can differ from the design fatigue evaluation result. In order to evaluate and monitor the FUF exactly, therefore, various methods have been proposed and widely implemented. Among these, the cycle-based approach (CBA) utilizes the stresses for the design transients and reflects only the actual number of transient occurrences. For this reason, the CBA provides a conservative FUF, although it is very simple and easy to implement. Therefore, a simple and accurate fatigue monitoring method is still needed.
The purpose of this paper is to develop a new approach for effective fatigue damage monitoring. To do this, a thorough review is conducted for the design transients and actual transients for the Westinghouse-type pressurized water reactors in Korea. In addition, a wide range of finite element analyses are carried out varying the heating/cooling rates and the pattern of the transients. Based on this result, a new CBA is proposed incorporating the simple correction factors for both the heating/cooling rates and the transient patterns. A case study is also carried out for the reactor pressure vessel outlet nozzle to verify the validity and applicability of the proposed method. The result indicates that the proposed method can provide a realistic FUF, and more importantly, it is very easy to implement. From these, it is anticipated that the new approach can be widely used in practical fatigue monitoring of nuclear components and piping.
