The Study of the Probabilistic Risk Assessment to The Dry Storage of Spent Nuclear Fuel

• Main Authors: Yi-Yuan Chen, 陳逸原
• Other Authors: Kuen Ting
• Format: Others
• Language: zh-TW
• Published: 2008
• Online Access: http://ndltd.ncl.edu.tw/handle/cxua77

碩士 === 龍華科技大學 === 工程技術研究所 === 96 === Due to the large demand from the industry development of the energy since 1960s, the nuclear power planets have been consistent constructed throughout the world in order to maintain and supply the basic electricity generation capacity demand. From the up to date, most of the planets have been operated for a certain period of time; therefore, the capacity of the spent fuel pool reaches its design capacity volume. In order not to be ceased the plant unit operation due to the spent fuel bundle exceeded the containing capacity within the spent fuel pool, the dry cask storage can provide a solution for both the spent fuel pool capacity and the storage method of the spent fuel bundle at nuclear power planet. Currently, the dry cask storage system and relevant operating procedures have also been gradually employed and consistent developed in order to facilitate the dry storage for the spent fuel bundles. In other word, spent fuel bundles dry storage and its safety will become an important issue and will directly affect the smooth operation to the plant once the spent fuel pool reaches its design capacity. Plants in United States, Nuclear Regulatory Commission, the Office of Nuclear Material Safety and Safeguards (NMSS), the Office of Nuclear Regulatory Research (RES) and Spent Fuel Project Office (NMSS) have jointly developed a pilot methodology for probabilistic risk assessments by adopting recently well developed quantitative and qualitative methods to the subject BWR plants. Based on the three major dry storage handling, transfer and storage phases dividing into 34 operation stages, implemented risk assessment obtaining the annual risk for one cask in terms of the individual probability of a prompt fatality within 1.6 km and a latent cancer fatality within 16 km of the subject BWR plant. This study assesses the potential initiating events, the releasing probabilities of the spent fuel bundles or multi purpose canister and the failure frequency of the secondary containment isolation within the individual stage of the 34 stages. Source Term and Consequences analyses establish the evaluation models in order to satisfy the postulated release scenarios. With the insufficient data or parameters during the assessment, this study refers NUREG-1864 “A Pilot Probabilistic Risk Assessment of a Dry Cask Storage System at a Nuclear Power Planet “related generic data and built prototype models implementing risk assessments in accordance with Taiwan BWR nuclear power plants. According to the requirements of the risk evaluation models at each stage, multiplies the obtained frequency of the initiating event, releasing probability of the spent fuel bundles or multi purpose canister and the failure frequency of the secondary containment isolation, fraction of the release from the source term and frequency of the consequence into an aggregated risk at each stage. Then, sums up each aggregated risk of the 34 stages obtaining the first year total risk attributing to the individual probability of a prompt fatality within 1.6 km and a latent cancer fatality within 16 km of the subject BWR plant. For the outcomes of this study, it can be as a reference for further more detailed developments of the dry cask storage system risk assessments for Taiwan BWR nuclear power planets.