SITE EVALUATION AND VOLCANIC HAZARD ASSESSMENT FOR THE NUCLEAR POWER PLANTS OF CHINA |
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| Authors: | XU Jian-dong YU Hong-mei ZHOU Ben-gang CUI Wen-ling DU Long WEI Fei-xiang |
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| Affiliation: | 1. National Observation and Research Station of Changbaishan Volcano, Antu 133613, China;
2. Institute of Geology, China Earthquake Administration, Beijing 100029, China;
3. Emergency Management Information Center of Shenzhen City, Shenzhen 518035, China;
4. China Nuclear Power Design Company Ltd. (Shenzhen), Shenzhen 518000, China |
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| Abstract: | Starting from the 1980's of last century, China has launched the national plan of constructing nuclear power plants along the coastline region in eastern China. Currently, in some of these candidate sites, nuclear facilities have been installed and are in operation, but some other nuclear power plants are still under construction or in site evaluation. In 2012 the Atomic Energy Commission issued the specific guide for volcanic hazards in site evaluation for nuclear installations(IAEA Safety Standards Series No. SSG-21), which was prepared under the IAEA's program for safety standards. It supplements and provides recommendations for meeting the requirements for nuclear installations established in the safety requirements publication on site evaluation for nuclear installations in relation to volcanic hazards. To satisfy the safety standards for volcanic hazard, we follow the IAEA SSG-21 guidelines and develop a simple and practical diffusion program in order to evaluate the potential volcanic hazard caused by tephra fallout from the explosive eruptions.
In this practice, we carried out a case study of the active volcanoes in north Hainan Province so as to conduct the probabilistic analysis of the potential volcanic hazard in the surrounding region. The Quaternary volcanism in north Hainan Island, so-called Qiongbei volcanic field is characterized by multi periodic activity, in which the most recent eruption is dated at about 4 000a BP. According to IAEA SSG-21, a capable volcano is one for which both 1)a future eruption or related volcanic event is credible; and 2)such an event has the potential to produce phenomena that may affect a site. Therefore, the Qiongbei volcanic field is capable of producing hazardous phenomena that may reach the potential nuclear power plants around. The input parameters for the simulation of tephra fallout from the future eruption of the Qiongbei volcanic field, such as the size, density and shape of the tephra, the bulk volume and column height, the diffusion parameter P(z), wind direction and intensity, were obtained by field investigation and laboratory analysis. We carried out more than 10000 tephra fallout simulations using a statistical dataset of wind profiles which are obtained from China Meteorological Data Sharing Service System(CMDSSS). Tephra fallout hazard probability maps were constructed for tephra thickness threshold of 1cm. Our results show that the tephra produced by the future large-scale explosive eruption from the Qiongbei volcanic field can affect the area in a range about 250km away from the eruption center.
In summary, the current key technical parameters related to volcanic activity and potential hazards in IAEA/SSG-21 guidelines, such as 10Ma volcanic life cycle and 1×10-7 volcanic disaster screening probability threshold, etc. are based on the volcanic activity characteristics in the volcanic island arc system. In consideration of the relatively low level of volcanic activity compared with volcanic island arc system due to the different tectonic background of volcanism in mainland China, the time scale of volcanic disaster assessment in IAEA SSG-21 guideline is relatively high for volcanoes in mainland China. We suggest that the study of "conceptual model" of volcanic activity should be strengthened in future work to prove that there is no credible potential for future eruptions, so that these volcanoes should be screened out at early stage instead of further evaluation by probabilistic model. |
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| Keywords: | site evaluation nuclear power plant volcanic hazards IAEA/SSG-21 guideline probabilistic tephra fallout hazard evaluation |
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