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Chapter 9 Siting

consideration to reflect future investigations and world trends.

      1. Hie Concept of Site Safety in the iaea Site Safety Standard

As examples of standards for nuclear power plant siting (Ref^and3), IAEA has established the Safety Standards Series “Site Evaluation for Nuclear Installations (No. NS-R-3)” and the Japanese Nuclear Safety Commission has established the “Regulatory Guide for Reviewing Nuclear Reactor Sting Evaluation and Application Criteria”. A brief introduction is given for the IAEA document “Site Evaluation for Nuclear Installations” which was published in December 2003.

The "Site Evaluation for Nuclear Installations” sets forth the principle that the principal requirement for siting is to ensure adequate protection of site personnel, the public and the environment from the effects of ionizing radiation arising from nuclear installations. And also the scope of the investigation for the site of a nuclear installation covers the entire process of the site evaluation — the selection, assessment pre-operational and operational stages It further states the purpose of siting and other general requirements as follows.

(1) The objective of site assessment<l f 2)

Hie main objective in site evaluation for nuclear installations in terms of nuclear safety is to protect the public and the environment from the radiological consequences of radioactive releases due to accidents. Releases due to normal operation should also be considered. In the evaluation of the suitability of a site for a nuclear installation, the following aspects shall be considered.

  1. The effects of external events occurring in the region of a particular site (these events could be of natural origin or human induced.)

  2. The characteristics of the site and its environment that could influence the transfer to persons and the environment of radioactive material that has been released.

  1. The population density and population distribution and other characteristics of the external zone in so far as they may affect the possibility of implementing emergency measures and the need to evaluate the risks to

individuals and the population.

(2) General criteria(K, 1 2)

  1. Site characteristics that may affect the safety of the nuclear installation shall be investigated and assessed. Characteristics of the natural environment in the region that may be affected by potential radiological impacts in operational states and accident conditions shall be investigated. All these characteristics shall be observed and monitored throughout the lifetime of the installation.

  2. Proposed sites for nuclear installations shall be examined with regards to the frequency and severity of external natural and human induced events and phenomena that could affect the safety of the installation.

  3. The foreseeable evolution of natural and human made factors in the region that may have a bearing on safety shall be evaluated for a time period that encompass the projected lifetime of the nuclear installation. These factors, particularly population growth and population distribution shall be monitored over the lifetime of the nuclear installation. If necessary, appropriate measures shall be taken to ensure that overall risk remains acceptably low. There are three means available to ensure that risks are acceptably low; design features, measures for site protection and administrative procedures. Design features and protective measures are the preferred means of ensuring that risks are kept acceptably low.

  4. The hazards associated with external events that are to be considered in the design of the nuclear installation shall be determined. For an external event (or a combination of events) the parameters and the values of those parameters that are used to characterize the hazards should be chosen so that their can be used easily in the design of the installation.

  5. In the derivation of the hazards associated with external events, consideration should be given to the effects of the combination of these hazards with the ambient conditions.

  6. In the analysis to determine the suitability of the site, consideration should be given to additional matters relating to safety such as

9-3

NSRA, Japan