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Hydrogen behavior in a large-dry pressurized water reactor containment building during a severe accident HSU Wen-Sheng1, CHEN Hung-Pei1, HUNG Zhen-Yu1, and LIN Hui Chen1
1. Institute of Nuclear Engineering and Science, National Tsing Hua University, R.O.C 101 Section 2, Kuang Fu Rd., HsinChu, R.O.C (E-mail: saabsaab11@hotmail.com)
Abstract: Following severe accidents in nuclear power plants, large quantities of hydrogen may be generated after core degradation. If the hydrogen is transported from the reactor vessel into the containment building, an explosion might occur, which might threaten the integrity of the building; this can ultimately cause the release of radioactive materials. During the Fukushima Daiichi nuclear accident in 2011, the primary containment structures remained intact but contaminated fragments broke off the secondary containment structures, which disrupted mitigation activities and triggered subsequent explosions. Therefore, the ability to predict the behavior of hydrogen after severe accidents may facilitate the development of effective nuclear reactor accident management procedures. The present study investigated the behavior of hydrogen in a large-dry pressurized water reactor (PWR). The amount of hydrogen produced was calculated using the Modular Accident Analysis Program. The hydrogen transport behavior and the effect of the explosion on the PWR containment building were simulated using the Flame Acceleration Simulator. The simulation results showed that the average hydrogen volume fraction is approximately 7% in the containment building and that the average temperature is 330 K. The maximum predicted pressure load after ignition is 2.55 bar, which does not endanger the structural integrity of the containment building. The results of this investigation indicate that the hydrogen mitigation system should be arranged on both the upper and lower parts of the containment building to reduce the impact of an explosion.
Keyword: severe accident; hydrogen explosion; PWR; FLACS |
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