Population distribution is one of several important factors to be considered in the siting of nuclear power plants. The present Guide, relating population distribution to site selection and evaluation, describes and supplements sub-sections 3.5 and 5.4 in the Code of Practice on Safety in Nuclear Power Plant Siting (HAF 101).
In the view of the international nuclear energy development, it is common practice to select the most suitable site away from the population center and at the zones with as low population density as possible, however, with the accumulated experience and technical progress, it is proved that the it is feasible to select the site at the area far away from the population center but with high population density. The low population density zones shall be selected in priority.
Currently, the nuclear power plant in China shall be selected at the zones far away from population center and the zones with low population density shall be selected in priority.
This Guide proposes requirements and method in accordance with the following common siting stage:
(1) Preliminary screening of the territory of interest by means of relatively simple and rough methods, aiming at the identification of possibly suitable or candidate sites;
(2) Selection of a proposed site or sites through a comparative assessment of several candidate sites, by means of more detailed methods taking into account specific site features;
(3) Final evaluation and licensing review of the selected site-plant combination.
The Guide presents population distribution data requirements, examples of site screening methods, and an overview of radiological impact assessment with respect to population distribution.
The minimum population data necessary for the entire siting process are described in section 2. It must be noted here that the population data shall be projected throughout the lifetime of the nuclear power plant, taking into account the possible influence of the presence of the nuclear power plant on population growth around the site and related impacts of planning policies.
Several methods for screening sites with respect to population distribution are described in section 3; the methods include simple ones that primarily compare only population distributions and more complex ones that include a more or less detailed consideration of meteorological data and collective dose calculations. The possibility of using suitable methods not described in section 3 is not excluded, but it must be proved to National Nuclear Safety Administration that they are equivalent in the aspect of safety level and do not post additional risks to people in the plant as well as the public.
The choice of the most appropriate screening and comparison methods from the point of view of population distribution shall be based on a consideration of the amount and quality of data available on other relevant regional characteristics such as meteorology and topography, and on the nature of those characteristics and the quality of the data on population distribution (e.g. whether or not there is a reliable national census).
For the preliminary screening, in order to identify possible sites in a region or a country, and then to compare those candidate sites that emerge from this screening, it is not necessary to have detailed information on plant type and safety related design features. However, for the purpose of final evaluation of the acceptability of one or more sites that are identified in the site comparison process, it is necessary to have basic information about the design of the proposed nuclear power plant, such as reactor type, power, and basic safety features. Therefore the method used for final evaluation of a population distribution around a proposed nuclear power plant shall take into account assumptions and safety analyses that may pertain to the characteristics of the proposed nuclear power plant. Final radiological impact evaluation shall include at least some consideration of the probability of accidental releases of radioactive materials and the radiological consequences of those releases on individuals and populations.
An overview of radiological impact assessment with respect to a population distribution is given in section 4.Until such capability is developed the usual practice is to evaluate the potential radiological impact of certain selected accidents. The selection of such potential accidents can only be based on engineering judgement, at least until the overall risk approach is sufficiently developed to be reliable.
Annex I introduces methods described in section 3; Annex II describes the basis for the method selection suggestion.
1 Introduction
2 Data Requirement
2.1 Population Data
2.1.1 Current Population
2.1.2 Projected Population
2.2 Other Information
2.2.1 Meteorological Data
2.2.2 Hydrological/Geohydrological Data
2.2.3 Additional Data
2.3 Data Format
2.3.1 Concentric Rings
2.3.2 Sectors
3 Territory Screening and Preliminary Site Selection Methods
3.1 General
3.2 Fixed-area Method
3.3 Cumulative Population Curve Method (for Reference)
3.4 Population Density Method
3.5 Site Population Factor Method
3.6 "Site and Sector Factor" Method
3.7 Site Population and Atmospheric Dispersion Method
3.8 Normalized Collective Dose Method
3.9 Discussion of Methods
4 Radiological Impact and Final Site Evaluation
4.1 General
4.2 Reference Accidents
4.2.1 Source Terms
4.2.2 Transfer to the Environment
4.2.3 Individual Doses
4.2.4 Collective Doses
4.2.5 Final Evaluation
4.2.6 Review of Plant and Site for Reduction of Potential Radiological Health Detriment
4.3 Doses for Normal Operation
Annex I Details of Methods Described in Section 3
Annex II Suggested Bases for Choice of Method
