The following discussion describes the existing regulatory framework, in context of reactor site criteria, general design criteria, quality assurance criteria, and other regulatory provisions applicable to assure the adequacy of various aspects of site location, design, construction, inspections, and testing of containment structure.
Reactor Site Criteria
Selection of site is one of the most important endeavors for locating a reactor facility. The 10 CFR Part 100 provides detailed requirements and guidance for selecting a site for a proposed reactor facility. The relevant parts of the requirements are discussed in the following paragraphs.
The basic characteristics, that the reactor facility applicant has to address are; (1) population density and the usage characteristics of the site environs, including the exclusion area, low population zone, and population center distance, (2) physical characteristics of the site, including seismology, meteorology, geology, and hydrology. Specifically, the following attributes need to be considered:
- • Appendix A of Part 100, “Seismic and Geologic Siting Criteria for Nuclear Power Plants,” describes the nature of investigations required to obtain the geologic and seismic data necessary to determine site suitability and to provide reasonable assurance that a nuclear power plant can be constructed and operated at the proposed site without undue risk to the health and safety of the public. It describes procedures for determining the quantitative vibratory ground motion design basis at a site due to earthquakes and describes information needed to determine whether and to what extent a nuclear power plant need be designed to withstand the effects of surface faulting.
- • Meteorological conditions at the site and in the surrounding area should be considered.
- • Geological and hydrological characteristics of the proposed site may have a bearing on the consequences of an escape of radioactive material from the facility. Special precautions should be planned if a reactor is to be located at a site where a significant quantity of radioactive effluent might accidentally flow into nearby streams or rivers or might find ready access to underground water tables.
- • Where unfavorable physical characteristics of the site exist, the proposed site may be found to be acceptable, if the design of the facility includes appropriate and adequate compensating engineering safeguards.
As an aid in evaluating a proposed site, an applicant should assume a fission produce release from the core, the expected leak rate from the containment, and the meteorological conditions pertinent to the proposed site to derive an exclusion area, a low population zone, and population center distance. For the purpose of this analysis, which shall set forth the basis for the numerical values used, the applicant should determine the following:
- • An exclusion area of such size that an individual located at any point on its boundary for 2 hours immediately following onset of the postulated fission product release would not receive a total radiation dose to the whole body in excess of 0.25 Sievert (Sv) (25 rem), or a total radiation dose in excess of 3.0 Sv (300 rem) to the thyroid from iodine exposure.
- • A low population zone of such size that an individual located at any point on its outer boundary who is exposed to the radioactive cloud resulting from the postulated fission product release (during the entire period of its passage) would not receive a total radiation dose to the whole body in excess of 0.25 Sv (25 rem) or a total radiation dose in excess of 3.0 Sv (300 rem) to the thyroid from iodine exposure.
- • A population center distance of at least one and one-third times the distance from the reactor to the outer boundary of the low population zone. In applying this guide, the boundary of the population center shall be determined upon consideration of population distribution. Political boundaries are not controlling in the application of this guide. Where very large cities are involved, a greater distance may be necessary because of total integrated population dose consideration.
When a site is proposed for construction of multiple reactor facilities, the applicant is expected to show that the simultaneous operation of multiple reactors at a site will not result in total radioactive effluent releases beyond the allowable limits of applicable regulations. For further information in developing the exclusion area, low population zone, and population centers, the readers should refer to Technical Issue Document (TID) 14844 (1962) . The calculations described in TID 14844 may be used as a point of departure for consideration of particular site requirements which may result from evaluation of the characteristics of a particular reactor, its purpose, and method of operation.
In addition to the above relevant information, Part 100 provides (1) factors to be considered when evaluating sites, (2) non-seismic site criteria, and (3) geologic and seismic site criteria.