1. Introduction
With the rapid development of China’s economy, comes the pressure on energy supply and environmental protection. To tackle this problem, nuclear power has been adopted as a sustainable energy development strategy. On March 22nd, 2006, the State Council passed the “Medium- and Long-term Nuclear Power Development Plan (2005-2020)”. At present about 20 provinces in China are investigating sites for future nuclear power plants. Yet with a huge population and unbalanced economic development, the power plant siting remains a concern for nuclear safety regulators and nuclear siting investigators. This paper focuses on China’s nuclear power siting and environmental impact assessment employing the expertise of personal experience and industry participants.

2. Nuclear safety and environmental protection ion nuclear power siting.
Through the preparation and assessment of the project planning, site selection, and preliminary feasibility reports of numerous nuclear power projects, the following concerns of about nuclear power siting have been identified as crucial to nuclear safety and environmental protection.

2.1 Regulations on nuclear power sitting
According to China’s Safety Requirements on Nuclear Power Plant Siting, as well as international related regulations, three basic concerns should be addressed when doing nuclear power plant site investigation. The first concern is the possible impact on the nuclear power plant that could result from natural or human sources. The second concern is the impact the nuclear power plant will have on its surroundings including both the natural and social environment. The third concern is the feasibility of implementation of emergency plans. That is to say, how the surroundings would affect the execution of necessary actions in the case of an emergency. For each plant siting case, once the three previous points have been confirmed, or engineering measures have been determined to address the disadvantages that may exist, the site may be approved to support a nuclear power plant.

2.2  Civil aircraft on the safety of nuclear power plant
Human Factors on Nuclear Power Plant Siting (HAD101/04) gives a detailed description of the impact civil aircrafts have on the safety of a nuclear power plant. According to the nuclear safety guidelines, nuclear power plants with a flight path or airstrip within 4km, need to consider the potential danger caused by aircrafts. There are two cases in which potential sites have flight paths within less then 4km. Statistical analysis of the average accident rate over that last ten years gives the risk of an airplane crash a probability of less than or equal to 10-8, below the HAD101/04 screening level of 10-7 . Due to this result, in future siting for Nuclear Power Plants within 4km of a flight path or airstrip, the potential danger of a plane crash can be dismissed.

3. Environmental Impact Assessment
Preparation of a Nuclear Power Plant Environmental Impact Report must take the following points into consideration. Hopefully, presenting these points will induce valuable comments and suggestion on nuclear power plant siting.
3.1 When preparing a CPR1000 nuclear power plant environmental report, radioactive sources are selected to calculate the dose of radiation will that would result from operation. For this calculation, only some of the units are projected to reach their designed figure of effluents output (case B). As an example, to prepare the environmental impact report for a 6 unit site, three approaches can be taken. First, there could be an even split of 3 units reaching their designed figure (case B) and the other 3 units only reaching their expected figure (case A). Other approaches calculate output based on 2case B + 4case A or 4case B + 2case A. All of these approaches are conservative estimates, and in theory, the radiation impact calculated from this should be an exaggerated figure. According to chapter 11 in AP1000 Design Control Document, caseCASE B should be applied to the shield calculation, and caseCASE A should be applied to the environmental impact assessment report.

The AP1000 Design Control Document has a more reasonable approach. Choosing the expected figure of emissions of radioactive effluents as the radiation figure for the environmental impact evaluation report more truthfully reflects the impact the nuclear power plant has on the environment. Thus, this exaggeration of nuclear radiation impact on the environment can be avoided.

In preparing the environmental impact report for third generation nuclear power plants (e.g. AP1000 and EPR), care should be taken to select radiation sources that truly reflect the impact that the nuclear power plant has on the environment.

3.2 Emissions of low level liquid waste
Low level waste from nuclear power plants is discharged to the sea for coastal nuclear power plants and into surface water for inland nuclear power plants. Coastal nuclear power plants have better heat dispersion conditions because most coastal nuclear power plants are located in low hilly areas of bedrock. This allows the radiation output to be minimized. Because of limitations on water and environmental characteristics of inland water systems, the heat dispersion conditions and influencing factors of inland nuclear power plants can be complicated. At present, most of the potential nuclear power plant sites located beside rivers with heavy flow have good dispersion conditions, but most of these areas are already developed. They already have an established economies and dense populations, and often the rivers are the primary drinking water resource for residents.

Within the nuclear waste discharged from a nuclear power plant, liquid waste constitutes 80% of the radiation dose to the local population. That is why liquid waste from nuclear power plants is the key factor in environmental protection assessment, especially for inland nuclear power plants.

At present, regulations on emissions of low-level liquid waste from nuclear power plants include Radiation Protection Requirements of Nuclear Power Plants （GB6249-86） and Liquid Waste Emission Requirements of Light Water Reactor （GB14587-1993）.（GB6249-86）regulates the annual amount of liquid waste and gas waste, but not the radionuclide concentrations. (GB14587-1993) also has no specific regulations on the radionuclide concentrations from the nuclear power plants.

Now with the large scale development of nuclear power plants and public awareness on nuclear power, the Ministry of Environmental Protection of the People’s Republic of China has been revising （GB6249-86）and（GB14587-1993）. Radionuclide concentration is limited in the new versions. From the point of environmental protection and the public safety, it is reasonable to add this limitation on radionuclide concentration. Once the new versions of （GB6249-86）and（GB14587-1993）come into effect, improvements will be made to the waste treatment systems of the now existing CPR1000 reactors to reduce their emissions.

3.3 Emergency Management of Nuclear Power Plants
1. Population distribution around the nuclear power sites
At present, regulations and guidelines on evaluation of population distribution around nuclear power sites include Nuclear Power Siting and Population （HAD101/03） and Regulation on Nuclear Power Radiation Protection （GB6249-86）. Classification of population distribution can be made according to the above two regulations, but there is one special case for an island nuclear power site which has water and no human beings living within a 6km radius. This is classified as type I population density by the（HAD101/03）, but located 10km away there is a population center of about 200,000 people. According to （GB6249）, the island site is not appropriate to support a nuclear power plant because it exceeds the maximum population of 100,000. With development of advanced nuclear power technology, the third generation technology does not require off-site emergency support and has minimal effect outside 5km of the site. In this case, the population distribution evaluation should be made according to the site specific situation.

4. Classification of non-residential areas
A detailed description of non-residential area classification is given in (GB6249). Using the worst case accident scenario along with local meteorological data, the effective dose and thyroid dose are calculated. These statistics determine which areas can be classified as non residential area. Drawn from personal experience, the most important factor in deciding the size of the non-residential area is its weather condition. In coastal nuclear power sites, where the atmospheric dispersion conditions are relatively good, the radius of non-residential areas can be less than the 500 meter limit of (GB6249). For some inland nuclear power plants which have relatively bad atmospheric dispersion conditions, the radium can exceed 2000 meters. With such a large population and limited land, China cannot afford to have such large areas restricted as non-residential.

In the draft version of the (GB6249), limits on the thyroid dose near the non-residential areas have been relaxed. This actually results in a relaxation of the requirements for non-residential areas, which can conserve land. With the development of nuclear technology more and more land can be conserved.

2. Conclusion.
At present, China is in a new period of nuclear power development. The investigation of nuclear power plant sitings has been launched nationwide. Due to the complexity of factors necessary to evaluate a possible nuclear power plant, the points made above are only a small segment determined through personal experience. More attention ought to be given on the area, and issues not mentioned above ought to be addressed later.

 Authors:

This article, originally titled 'The subject deserving wide attention for nuclear power plant siting and environmental impact assessment',  is co-composed byLiyong, li Wenhui and Zhang Ling from Design Institute of China Guangdong Nuclear Power Engineering.

Source:

This article was published on CHINA NUCLEAR POWER (No. 3 - 2009), in which the following articles are included

To strengthen the backbone of China’s nuclear industry-special interview with academician Li Guangxing     by Li Zhaoxu  Wei Guanggang
Speeding up the development of world third generation nuclear power technology        by Ding Zhongzhi
Study on ADS and the sustainable development of nuclear energy                  by Zhang zhixing, Xia Haihong
Controlled nuclear fusion and ITER project       by Feng kaiming
The evaluation method for nuclear island construction capacity of ENEC    by Zu Bin
Experiment and application of cement-based grout material in Tianwan NPP  by Qian Fu-hua, Wang Kaihua, Fang Hui-huang
Building the feedback system of project experience, and expediting the scientific development of nuclear power construction.  by Zhou Hai
Fault diagnosis of rolling bearing based on cyclic spectrum density.    by Shi Qingfeng   Zhang Yanhong, Yan Junming
Repair of evaporator of eyelet sealing face.   by Guo Hongyu
Learning Effect and Standardization Effect in NPP’s Construction   by Kang Yexi,  Xiao Dingsheng, Si Guojian
Design Management in the EPC of nuclear power project    by Li Jingyan
Application of pressurized gas storage and activated carbon sorption syatem in gaseous radioactive waste processing for NPPs.  by Chen Liang, Rao Zhongqun
Application research of cost construction on radioactive waste management.  byGao Yanfeng, Bi Sheng, Liu Zhen he
Exploring the new development approach of nuclear power insurance mode in China.  by Zhang Dong yan
Technical evolution of leading nuclear power reactor types in the world.  by Zhang Ruiping, Zhang xue, zhang lu qing

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