Spent Fuel Storage Operational Experience With Increased Crud Activities
Conference
·
OSTI ID:21319770
- Public Agency for Radioactive Waste, Management (PURAM) (Hungary)
- Paks NPP (Hungary)
- Technical University of Budapest (Hungary)
- SOM System Llc, (Hungary)
A significant part of the electricity production in Hungary is provided by 4 units of VVER 440 nuclear reactors at the Paks Nuclear Power Plant. Interim dry storage of the spent fuel assemblies that are generated during the operation of the reactors is provided in a Modular Vault Dry Storage (MVDS) facility that is located in the immediate vicinity of the Paks Nuclear Power Plant. The storage capacity of the MVDS is being continuously extended in accordance with spent the fuel production rate from the four reactors. An accident occurred at unit 2 of the Paks Nuclear Power Plant in 2003, when thirty irradiated fuel assemblies were damaged during a cleaning process. The fuel assemblies were not inside the reactor at the time of the accident, but in a separate tank within the adjacent fuel decay pool. As a result of this accident, contamination from the badly damaged fuel assemblies spread to the decay pool water and also became deposited onto the surface of (hermetic) spent fuel assemblies within the decay pool. Therefore, it was necessary to review the design basis of the MVDS and assess the effects of taking the surface contaminated spent fuel assemblies into dry storage. The contaminated hermetic assemblies were transferred from the unit 2 pool to the interim storage facility in the period between 2005 and 2007. Continuous inspection and measurement was carried out during the transfer of these fuel assemblies. On the basis of the design assessments and measurement of the results during the fuel transfer, it was shown that radiological activity values increased due to the consequences of the accident but that these levels did not compromise the release and radiation dose limits for the storage facility. The aim of this paper is to show the effect on the operation of the MVDS interim storage facility as a result of the increased activity values due to the accident that occurred in 2003, as well as to describe the measurements that were taken, and their results and experience gained. In summary: On the basis of the design assessments and measurement of the results during the fuel transfer operations, it was shown that radiological activity values increased due to the consequences of the 2003 accident but that these levels did not compromise the release and dose limits for the fuel storage facility. In the environment there was no measurable radioactivity as a result of the operation of the Paks ISFSI. The exposure of the surrounding population was calculated on measured releases and meteorological data. The calculations show negligible doses until 2004. Due to the increased surface contamination on the spent fuel assemblies the dose rate increased almost 5 times compared to the least annual value, but still less then 0.01 percent of the allowed dose restriction. (authors)
- Research Organization:
- WM Symposia, 1628 E. Southern Avenue, Suite 9 - 332, Tempe, AZ 85282 (United States)
- OSTI ID:
- 21319770
- Report Number(s):
- INIS-US--10-WM-08243
- Country of Publication:
- United States
- Language:
- English
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