School for drafting regulations Nuclear Safety Siting and site evaluation Vienna, 26 November -7...

School for drafting regulations Nuclear Safety

Siting and site evaluation

Vienna, 26 November -7 December 2012

Tea Bilic Zabric

Introduction

How are sites evaluated?How is the preferred site selected?How is the preferred site licensed or permitted?How does the safety regulator oversee site preparation activities?

Introduction

Do you, or another decision-making body, regulate the selection of sites for nuclear facility?

Key elements of the legislative framework (i.e. statutes or regulations) that apply to site selection?

Any informal guidance that describes what is expected of a proponent when seeking a decision?

Introduction

Nuclear ActNuclear DecreeGovernment DecisionsRegulatory Guides (for Siting)Environmental Impact Assessment Act and DecreeSpatial planning and Building ActSite selection is influence by many other fields of legislation and international treaties (water, nature)

Introduction

Meetings and correspondence on a case by case basis. Licence applicant can ask for preliminary opinions on plans and designs according to long term strategic planning.

Introduction

To what extent do your legislative framework or regulatory expectations draw from, NS-R-3?

The national siting requirements can be presented in a number of legislative documents according to national hierarchy of legislation.The procedural requirements and technical requirements are usually in different documents.

Introduction

Do you require or recommend that the applicant evaluate various sites before selecting a particular site?

It is a normal practice when a new site is selected.Regarding projects for building additional units on the existing sites, the utilities have not been required to considered new sites as an alternative.

Introduction

Guidance regarding expectations for the depth of evaluation of alternative sites?In practice, the depth of evaluations is determined by the level of information which has been collected for the existing sites in connection with the licence renewals, licensing of the new unit and the associated environmental impact assessments, operating experiences, external events PSAs and emergency preparedness planning.

(IAEA standards and guides)

Introduction

Do you require any form of environmental assessment to be performed as part of site selection or before site preparation may begin?

An Environmental Impact Assessment is required according to the European Union Directive and national Environmental Impact Assessment Act and Decree??

Introduction

Do you require an applicant to give special consideration to any natural factors, such as seismicity, geotechnology, meteorology or hydrology?

All the mentioned factors have to be considered in the site evaluation to determine an adequate design basis. (location of site is important)

Introduction

Do you require an applicant to give special consideration to any man-made factors, such as climate change, fires, nearby transportation routes or malevolent events?

All of these factors shall be considered. Special emphasis is given to transportation, especially for sites in the vicinity of park of nature or water sources.

Introduction

Do you, or another body, require an applicant to take transmission access or adequacy into account at the site selection stage?

It is a part of the site suitability assessment. The suitability of the site regarding the national power grid and its reliability is one factor considered in the licensing process. The Ministry …. is responsible for non-safety issues in site selection and licensing.

Introduction

Are there any requirements or expectations that an applicant consult the public, either prior to applying or subsequently?The applicant should be required by the law to provide information to the public and arrange interaction with the public as part of the hearing process at several stages: environmental impact assessment program and report, construction licence and operating licence.

Introduction

Are there any requirements or expectations that an applicant consult the public, either prior to applying or subsequently?Public information is emphasised especially during the EIA. Interaction with the public in the site municipality is considered especially important in the early phases of the decision making process as the acceptance of the local municipal council is a necessary prerequisite for a Government decision.

Introduction

Are there any requirements or expectations that the regulatory body or other government agency consult the public?Land use planning on the regionaland local levels also includes hearing of the public. In addition, non-mandatory information and discussion meetings have been arranged by the site municipalities which have invited experts, e.g. from the regulatory authority.

Introduction

Are there any other elements of national practice that would be relevant (such as projecting population growth around the selected site for the life of the station, controlling land use, considering the feasibility of emergency measures)?

Number of permanent residents in the protective zone (5 km radius) can be limited. Though this is not an absolute requirement, it sets some boundary conditions on site selection

Defense in depth and site safety

Site selection is a multi multi-faceted process where safety considerations largely dominate and provide two distinct levels of defence defence-in-depth:

The first level of site selection is preventive and aims at decreasing the reactor’s exposure to externals hazards.A comprehensive process of screening out sites where hazards are too important and a proper determination of a reactor design basis for the selected site(s).

Defense in depth and site safety

The second level is related to mitigation and aims at decreasing the reactor’s impact on the environment.

It involves selection of a site(s) with good dispersion characteristics of radionuclides in the air and water and a favourable terrain and infrastructure for implementation of an emergency plan.

A site for nuclear facility

The selection and the evaluation of the site for a nuclear power plant are crucial parts of establishing a nuclear power programme and can be significantly affected by:

costs, public acceptance, safety considerations

The site is unique, there is no “standard” site

Introduction

Need for clear criteria and regulatory requirements:

The site selection process needs to be guided by a clearly established set of criteria or regulatory requirements. A global balance has to be established between the characteristics of a site, on the one hand, and specific design features, site protection measures and administrative procedures, on the other hand, in order to obtain an acceptable solution.

Introduction

Need for support in the first phases of the NPP programme:

NPP project organization lacks expertise in the site related topics . . . and the national specialized institutions with such expertise have lack experience in nuclear projects.

Introduction

Need for support in the first phases of the NPP programme:

A balance is needed to equip the NPP project team with sufficient knowledge to be an ‘intelligent customer’ on the subject.It is necessary to provide adequate training to those specialized institutions before they start their site contractual work.

Selection of the site

There is a need to ensure that potential suitable site(s) are available from the very beginning of the programme. As the process progresses to screen out more and more potential sites, the safety aspects become more important. The data collected and the methods used for these few sites need to be treated with similar care as for the finally selected site. Technology, economics, non non-radiological environmental, impact, public opinion, play important role

Key decision

Decision regarding the ‘suitability’ of the preferred candidate site, i.e. confirmation that the site has no characteristics that would preclude the safe operation of a nuclear installation.

Decision related design basis parameters, e.g. to be used in tender and design documents.

Key decision

The approval of the PSAR which, inter alia, demonstrates that the site related design basis parameters have been appropriately accounted for through conservative design, site protection measures or administrative means.

Selection of the site -stages

The site selection process, also called siting for a new nuclear installation, is divided into two stages. In the first stage, ‘site survey’, potential sites are considered on the basis of existing available data and suitable candidate sites are chosen

The second stage, ‘site selection’, is aimed to select the site and is the completion of the site selection process.

Selection of the site-stages

In stage 3, the acceptability of the selected site is confirmed, its complete characterization is performed and the site related parameters needed for the design of the nuclear power plant are derived

SITE SURVEY AND SITE EVALUATION-PHASE 1ACTION 160:

The government should ensure that potential sites are identified and candidate sites are selected on the basis of a set of defined criteria, at a regional scale and with the use of available data

If the operating organization is already established or identified in Phase 1 it should be involved in the site survey


The regulatory body should establish specific safety requirements for site evaluation, including requirements for the process for authorizing the site selected, in compliance with the relevant IAEA safety standards.


The operating organization should complete the investigations relating to the suitability of the candidate sites and should select the preferred candidate site for the first nuclear power plant, making use of specific data, information and studies, and assessments conducted on the fullest possible temporal and spatial scales of investigation.


The operating organization should prepare the site evaluation report and should submit it to the regulatory body, on the basis of a full assessment of the site selected and including the confirmation of site acceptability and the characterization of the site for the definition of the site related design basis parameters.


The regulatory body should review and assess the site evaluation report, and should make a decision regarding the acceptability of the site selected and the site related design bases.


The operating organization should use all the appropriate information relevant to safety and to regulatory control that is related to or derived from the site assessment to prepare the bid specifications for the nuclear power plant.


The operating organization should start to evaluate and modify the site and radiological environmental monitoring programme as necessary after the site evaluation report has been approved.


The operating organization should prepare the chapter on site evaluation of the safety analysis report, and then update it, taking into account the specificities of the reactor selected and the data and information gathered during the pre operational stage.


The operating organization should implement necessary safety improvements to the site, if required, as site protection measures determined as a result of the tasks of external hazard assessment.

ACTION 169: The operating organization should continue to implement the environmental programme and the site monitoring programme.

NS-R-3: Requirements for Site Evaluation

Content:General requirements Specific requirements for evaluation of external events Site characteristics and the potential effects of the nuclear installation in the region Monitoring of hazardsQuality assurance.

NS-R-3: Objectives

Establish the requirements to be applied for:

• Defining the extent of information to be presented by the applicant for a proposed site;

• Evaluating a proposed site to ensure that the site related phenomena and characteristics are adequately taken into account;

NS-R-3: Objectives

Establish the requirements to be applied for:

• Analyzing the population characteristics of the region and the capability of implementing emergency plans throughout the projected lifetime of the installation;

• Defining site related hazards.

NS-R-3: Objectives

Nuclear installations: nuclear power plants, fuel cycle facilities, spent fuel storage installations, research reactors and reprocessing plants.

The level of detail needed to meet the requirements of this document vary according to the type of installation being sited or evaluated

NS-R-3: General Requirements

Effects of external events occurring in the region of the particular site (natural or human induced). Characteristics of the site and its environment which could influence the transfer of released radioactive material to persons. Population density and distribution and other characteristics of the external zone in relation to the possibility of implementing emergency measures and the need to evaluate the risk to individuals and the population.


If the site evaluation indicates that the site has serious deficiencies that cannot be compensated for by means of: (a)design features, (b)site protection measures, or (c) administrative procedures, the site shall

be deemed unsuitable.

Design features (a), and site protection measures (b), are the preferred methods of ensuring that risks are kept acceptably low.


In addition to providing the technical basis for the safety analysis report to be submitted to the nuclear regulatory authority, the technical information developed in compliance with this safety standard also addresses requirements associated with the (radiological) environmental impact assessment for potential radiological hazard.

NS-R-3: General Criteria

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

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 encompasses the projected lifetime of the installation.

NS-R-3: Criteria for external hazard

Time scales:

Pre-historical, historical and instrumental information and records, as applicable, of the occurrences and severity of those important natural phenomena or human induced collected for the region and carefully analyzed for reliability, accuracy and completeness.


• Appropriate methods shall be adopted for establishing the hazards from external phenomena.

• The methods shall be justified as being compatible with the characteristics of the region and the current state of the art. Preferential consideration should be given to applicable probabilistic methods.

• It should be noted that probabilistic hazard curves are generally needed to conduct external event PSAs.


Size of the region: Spatial scales The size of the region to which a method for establishing the hazards associated with major external phenomena is to be applied shall be large enough to include all the features and areas that could be of significance in the determination of the natural and human induced phenomena under consideration and for the characteristics of the event. seismic evaluations


Site specific data:

In determination of hazards, site specific data shall be used, unless such data are unobtainable. In this case, data from other regions that are sufficiently relevant to the region of interest may be used.

NS-R-3: Criteria for Potential Effects of the Nuclear Installation in the Region

In evaluation of a site to determine its potential radiological impact on the region for operational states and accident conditions which could lead to emergency measures, appropriate estimates shall be made of expected or potential releases of radioactive material, taking into account the design of the installation and its safety features.

NS-R-3: Criteria for Potential Effects of the Nuclear Installation in the Region

• The direct and indirect pathways by which radioactive material released from the installation could potentially reach and affect people and the environment shall be identified and evaluated.

• In such an evaluation, specific regional and site characteristics shall be taken into account, with special attention to the function of the biosphere in the accumulation and transport of radionuclides.

NS-R-3: Criteria for Considerations of Population and Emergency Planning

• The proposed region shall be studied to evaluate the present and foreseeable future characteristics and distribution of the population;

• Such a study shall include evaluation of present and future uses of land and water in the region; and

• Account shall be taken of any special characteristics that may affect the potential consequences of radioactive releases for individuals and the population as a whole.


The combined effects of the site and the installation shall be such that:

For operational states the radiological exposure of the population remains as low as reasonably achievable and, in any case, in compliance with national requirements with account taken of international recommendations;


The combined effects of the site and the installation shall be such that:

The radiological risk to the population associated with accident conditions, including those that could lead to emergency measures being taken is acceptably low. the potential consequences of radioactive releases for individuals and the population as a whole.


If, after thorough evaluation, it is shown that appropriate measures cannot be developed to meet the requirements, the site shall be deemed unsuitable for the location of a nuclear installation of the type proposed.


The external zone for a proposed site shall be established with a view to the potential for radiological consequences to people and to the capability of implementing emergency plans, having due regard for any external event or phenomenon which may hinder implementation.

NS-R-3: Hazards Monitoring and Quality Assurance

The site characteristics of relevance to the nuclear installation that are considered in this safety requirements and that are pertinent to the licensing and safe operation shall be monitored over the lifetime of the facility.

NS-R-3: Hazards Monitoring and Quality Assurance

A QA programme shall be established to control the effectiveness of the execution of the site investigations and assessments and engineering activities performed in the different stages of the site evaluation process, covering all activities that may influence safety or the derivation of parameters for the design basis.

NS-R-3: Specific Requirements for Dispersion and Population

Guidance on compliance with specific requirements for dispersion of radioactive material in air and water, the population distribution, uses of land and water in the region and feasibility of emergency plan are covered in a safety guide: “Plants”, NS-G-Dispersion of Radioactive Material in Air and Water and Considerations of Population Distribution in Site Evaluation for Nuclear Power Plants , NS-G-3.2

Comparison and Ranking Criteria

• The candidate sites are compared and ranked in order to identify the “preferred candidate site”, or several preferred candidate sites.

• Ranking involves cross comparison of sites with respect to all their attributes, both safety related and non-safety related.

• This may involve weighting of various attributes in a matrix form.


• It is also possible to quantify the differences of each site with respect to a reference site/plant combination.

• For many of the attributes it may be possible to use the differential cost (with respect to a reference site/plant combination) as the quantification parameter.


For safety related issues, comparison within topics is generally quite straightforward. For example, sites with relatively higher seismic hazard would be penalized in comparison with those in more stable areas.


What is more difficult is comparison across topics, in other words comparing a site with higher seismic hazard but lower flood hazard with another site having the opposite characteristics. There are various ways of dealing with this type of situation where weights may be assigned to different topics that contribute to the process.


• If there are an unreasonably large number of sites to be compared, then a screening process may be used first, whereby some preference (not exclusion) criteria are introduced to decrease the number of potential sites to a manageable number.

• This is an iterative process because if at the end of the initial preferential screening very few sites are left, then the criteria may be adjusted

New Units on Existing Sites

If the new site being considered is close to or adjacent to an existing nuclear installation site, then the existing site presents hazards to the new site, and once the new site is being developed and a new nuclear installation is operating, this in turn presents hazards to the existing site.


Design/operational restrictions on the new site may arise from operation of reactors on the existing site. For example, if an existing power reactor uses sea water cooling, its heat sink requirements may be significant in design of the heat sink of the power reactors on the new site, and the design of the heat sink facilities on the new site should take account of this.


The nuclear hazards arising from accidental events on the existing site may involve release of nuclear materials and/or radiation shine. The nature of accidental events will depend on the type of activities taking place, e.g. power reactor, nuclear spent fuel storage, and nuclear fuel reprocessing facility. Conventional hazards arising from accidents on the existing site involving, e.g. release of toxic chemicals, explosions, missiles, flooding, etc. may impact installations on the new site.


• Some hazardous events, e.g. loss of off Off-site electrical supplies, and most external hazards can initiate common cause failures across both sites, and the effects of this should be accounted for.

• Where the new facility forms part of an existing nuclear site, then the net effect of both facilities in terms of safety should be considered. In particular, compliance with dose and risk criteria should be maintained.

NS-R-3: Specific Requirements for Dispersion and Population

• NS-R-3 Site Requirements• NS-G-3.1 Human Induced Hazards• NS-G-3.2 Dispersion Air and Water• NS-G-3.3 Seismic Hazards• SSG-18 Meteorological and Hydrological Hazards• NS-G-3.5 Flooding Hazards• NS-G-3.6 Geotechnical Aspects• SSG-21 Volcanic Hazards• SSG-9 Seismic hazards.

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