Chapter 40: Regulatory Control of Nuclear Power Plants (Part 1)

This chapter was published on “Inuitech – Intuitech Technologies for Sustainability” on October 25, 2012.

It has indeed been and will continue to be the groundwork of nuclear regulation to ensure that nuclear power plants (NPPs) are operated and maintained in such a way that their impact on public health and safety is as low as possible.  No doubt the organizations, structures, and processes of regulatory authorities have evolved over the past 50 years but the mission of these regulatory bodies never changed.  Major changes to nuclear regulations were made around the world following each nuclear incident and the objective has always been not only to improve the effectiveness of the regulatory controls at each NPP but also to make them proactive.  However, factors other than events are beginning to have an impact on how regulatory authorities will need to function.  Economic factors, deregulation, technological advancements, government oversight and the general requirements for openness and accountability are some of the main elements that are leading regulatory bodies to look at their effectiveness. Seeking to enhance the present level of safety by continuously improving the effectiveness of regulatory bodies is seen as one of the ways to strengthen public confidence in the regulatory systems.

The fact of the matter is that both the regulator and the operator of a NPP have a common interest in resolving the safety issues.  It is recognized that it is the responsibility of the operator to safely operate the NPP, at the same time the regulator has responsibility for independently assuring that all NPPs are operated safely.   It is in the best interest of safety that the regulator and the operator work together in a professional manner to establish the basic facts in the situation and to agree on a plan to develop the additional data and information that is needed to continue to operate NPP safely.

In order to facilitate regulatory controls, it’s critical that a legal framework needs to be established that provides for the regulation of nuclear activities and for the clear assignment of safety responsibilities. Government is responsible for the adoption of legislation which assigns the prime responsibility for safety to the operating organization and establishes a regulatory body responsible for a system of licensing, for the regulatory control of nuclear activities and for enforcing the relevant regulations.

It is the responsibility of the regulatory body to set safety objectives and standards, and to monitor and enforce them within the established legislative and statutory framework. No other responsibility is to jeopardize or conflict with safety, its prime mission.  An important condition for the proper functioning of the regulatory body in discharging its responsibilities is its effective independence from organizations or bodies that promote nuclear activities. This is necessary so that its judgements may be made, and enforcement actions taken, without undue pressure from interests that may compete with safety. An additional important function of the regulatory body is to communicate independently its regulatory decisions and opinions and their bases to the public.

It is recognized that the application of fundamental principles of nuclear safety and the approach to the regulation of safety within the overall legislative framework may differ from country to country based on their legal systems, cultures, and practices, however, in all cases the regulatory body must have the statutory authority, competence, and resources in order to:

  • Set safety standards;
  • License and inspect installations;
  • Set, monitor and enforce licence conditions; and
  • Ensure that corrective actions are taken wherever unsafe or potentially unsafe conditions are detected.

None of these functions should be interpreted as reducing or relieving the operating organization of its responsibility for safety.  Other bodies may have professional or legal responsibilities that are significant to safety; for example, designers, manufacturers and constructors. Such bodies are also required to meet quality standards and specifications. Although the operating organization may delegate authority to carry out functions on its behalf, it cannot delegate the prime responsibility for safety.  The prime responsibility for the safety of the installation rests with the operating organization. It is responsible for specifying its safety criteria and assuring itself that the design, construction and operation of the installation meet the relevant safety standards. Subsequently, it is responsible for the establishment of procedures and arrangements to ensure the safe control of the installation under all conditions, for the establishment and maintenance of a competent and fully trained staff, and for the control of fissile and radioactive materials utilized or generated. The fulfilment of these responsibilities is to be in accordance with applicable safety objectives and requirements established or approved by the regulatory body.

The International Atomic Energy Agency (IAEA) performs two safety-related functions, which are laid down in its Statute.  These are:

  • Establishing standards of safety for the protection of health against the effects of radiation, and
  • Providing for the application of those standards at the request of a Member State.

The IAEA is devoting considerable efforts to nuclear safety activities world-wide by:

  • Facilitating the development of international legal agreements;
  • Developing safety standards which represent international consensus;
  • Offering international expert review and safety services and training; and
  • Fostering scientific research, technical co-operation and information exchange.

The IAEA has developed a comprehensive array of safety standards in the fields of nuclear energy, radiation protection, radioactive waste management and the transportion of radioactive materials.  At times, this has been done jointly with other international organizations. The standards are updated from time to time to ensure they can provide guidance on up-to-date methods for achieving a high level of safety.  As far as the regulatory control of NPPs is concerned, the IAEA has articulated the following guidance:


1.2       Regulatory Review and Assessment:

The basic objective of review and assessment is to determine whether the operator’s submissions demonstrate that the facility complies throughout its lifetime with the safety objectives, safety principles and safety criteria stipulated or approved by the regulatory body.  The specific objectives of the review and assessment depend on the stage of the lifetime of the facility.  Examples of specific objectives are listed below:

  • To determine whether an operator has the ability and resources to discharge its obligations associated with any authorization granted for any stage of the lifetime of the facility;
  • To determine whether the chosen site is suitable for the proposed facility, account being taken of the site–facility interaction and, anticipated changes to the site environment during the proposed period of operation, and to recommend to the appropriate authorities requirements on the site surroundings that may be considered necessary by the regulatory body;
  • To determine, before manufacture, construction, installation or decommissioning, whether the design related, operational or decommissioning related proposals in relation to the facility, and other operator statements and commitments, meet the regulatory body’s requirements, and to impose any further conditions or requirements that may be considered necessary by the regulatory body;
  • To determine whether the commissioning test programme is complete and contains a well defined set of operational limits, test acceptance criteria, conditions and procedures; whether the commissioning tests can be safely conducted; and whether the test results are adequate for confirming the adequacy of all safety related features of the facility;
  • To determine whether the operator has a safety management system that meets the regulatory body’s requirements;
  • To determine whether the operational limits and conditions are consistent with the regulatory body’s requirements, the operational characteristics of the facility and the state of knowledge and operational experience, and whether an adequate level of safety is maintained;
  • To determine whether the operator’s personnel, in terms of both number and competence, meet the regulatory requirements at all phases of the life-cycle of the facility;
  • To determine whether proposed modifications to the facility have been conceived and implementation planned so that safety is not compromised;
  • To evaluate safety reviews performed by the operator including performance indicators; and
  • To determine whether the operator’s statements and commitments regarding decommissioning and closure meet the requirements of the regulatory body.

The review and assessment is primarily based on the information submitted by the operator. For the thorough review and assessment of the operator’s technical submission the regulatory body acquires an understanding of the design of the facility or equipment, the safety concept on which the design is based, and the operating principles proposed by the operator. The regulator satisfies itself that:

  • The available information demonstrates the safety of the facility or proposed activity;
  • The information contained in the operator’s submissions is accurate and sufficient to enable verification of compliance with regulatory requirements; and
  • The technical solutions, and in particular any novel ones, have been proven or qualified by experience or testing or both, and are capable of achieving the required level of safety.

Management of the review and assessment within the regulatory body is an important part of the process. It includes planning, preparing guidelines, developing competence and necessary tools for review and assessment, co-ordinating information exchange and activities internally and externally, keeping a log on documents and actions, making arrangements for liaison with consultants and advisory bodies, monitoring the progress, collating and disseminating the overall findings and reporting the results of review and assessment.

1.2       Safety Objectives and Safety Requirements for Review and Assessment:

In formulating the content and structure of the safety objectives and safety requirements to be used in its review and assessment process, the regulatory body may consider a broad range of sources. Examples of these sources are:

  • National laws and regulations;
  • The requirements and experience of relevant national industries;
  • Technical results and experience of research and development;
  • Expertise and requirements used by other persons and bodies involved in reviewing and assessing similar facilities with respect to technology or safety implications;
  • Advice obtained from consultants and advisory bodies associated with the regulatory body; and
  • Nuclear, radiation and waste safety standards and guidance as well as other information published, by national and international organizations.

The regulatory body has a clear understanding, at all stages of the authorization process, of the basic safety objectives and safety requirements that will be used for review and assessment. As far as is practicable, these basic safety objectives and safety requirements are communicated to the operator for guidance in preparing its documentation.

1.3        Areas for Review and Assessment:

1.3.1     Site Evaluation:

In considering an application for siting, the regulatory body will tend to concentrate on characteristics of the site and, as appropriate, the interaction between the proposed facility and the site. Site selection for many facilities is initially determined by processes not greatly influenced by highly prescriptive criteria. However, general national policy requirements concerning remoteness, local population density and transport arrangements apply.

In all cases, the site of the facility is qualified by review and assessment to determine potential interaction between the proposed facility and the site, and the suitability of the site from the point of view of safety. This site review and assessment may be performed in parallel with the design review and assessment or, as in some member states, may be performed at an earlier stage. Areas of review and assessment that are of particular significance are the impact of the local environment, natural and human made on the facility’s safety and the demands that the facility will make on the local infrastructure.

1.3.2    Design, Construction, Manufacture, and Installation:

Before authorization of construction of the facility, review and assessment will be concentrated on the operator’s approach to safety and safety standards and how these have been applied in developing the design. Features such as the physical layout and building of the facility and the key process elements and expected radiation doses should be clearly understood as well as their effect on the safety of the facility throughout its lifetime are assessed at the design stage. In addition, before authorizing construction, the regulatory body reviews and assesses the operator’s arrangements for control of construction, manufacture and installation activities. Once construction has started, many features of the design can be changed only with great difficulty and at high cost.

Review and assessment of the design will continue during construction, manufacture and installation, as the details become finalized. Changes to the authorized design in this phase are analyzed by the operator and reported to the regulatory body which carries out the necessary review and assessment.

1.3.3     Commissioning:

Commissioning can be considered in two stages: inactive, before fissile material is introduced, and active, after fissile material is introduced. Clearly the radiological risks only arise after the second stage has been started and therefore it is normal to make the start of this stage a major step in the regulatory authorization. Both stages of commissioning are carried out against a programme which has been reviewed and assessed by the regulatory body and is capable of testing whether the as built facility meets the stated requirements.

The inactive stage of the commissioning is aimed at ensuring that the facility has been constructed, manufactured and installed correctly and in line with the design documentations.  Where deviations from this have occurred they have been recorded and it has been shown that the safety analysis has not been compromised. The results of inactive commissioning also confirm the operational features of the facility and lead to the development of detailed instructions for operators that will be confirmed during the active phase.

Active commissioning with the introduction of fissile material is a major step in the authorization process. The review and assessment take into consideration the final or ‘as built’ design of the facility as a whole, the commissioning programme and its progress, the organizational structure, the qualifications of operating personnel, emergency planning, the preliminary operational limits and conditions, and the preliminary operating procedures.

Where there are deviations from the design parameters, the regulatory body reviews and assesses additional analysis provided by the operator.

As the active commissioning processes move closer to completion, review and assessment are concentrated on how the facility is operated and maintained, and on the procedures for controlling and monitoring operation and responding to deviations or occurrences. Before authorizing routine operation, the regulatory body reviews and assesses the results of commissioning tests including correction of eventual non-conformances. The regulatory body reviews and assesses any proposed changes to the operational limits and conditions.

1.3.4    Operation:

For routine operation the regulatory body requires the operator to report regularly on adherence to safety objectives and compliance with specified regulatory requirements, and on efforts made to enhance safety. The regulatory body reviews and assesses the reports and performs inspections to confirm whether compliance with safety requirements is maintained and whether the facility is able to continue in operation.

While the need for reassessment may arise in a number of ways, systematic safety reassessments termed periodic safety reviews (PSRs) need to be carried out by the operator at intervals to review the cumulative effects of ageing of the facility and of modifications, and the implications of operating experience and technical developments. The objective is to assess the facility against current safety requirements and practices and to determine whether adequate arrangements are in place to maintain its safety. When a review shows that the facility does not meet current safety requirements, the significance of the shortcoming is assessed and the possibilities of meeting the requirements are considered. The PSR enables the regulatory body to judge whether it is acceptable for the facility to continue to be operated until the next PSR is carried out.

1.3.5    Decommissioning:

Review and assessment of decommissioning covers the decommissioning plant and the procedures and methods to be applied, the anticipated doses, the maintenance of safety and the final state of the facility at the end of decommissioning. An area of particular significance is the safe management of the radioactive waste generated.

1.4       Review and Assessment Methodology:

The review and assessment process is a critical appraisal, performed by the regulatory body, of information submitted by the operator to demonstrate the safety of the facility.  Review and assessment is undertaken in order to enable the regulatory body to make a decision or series of decisions on the acceptability of the facility in terms of safety. Decisions relating to safety are based on the review and assessment of the operator’s submissions, the studies and evaluations performed independently by the regulatory body itself, and the safety objectives and specific safety requirements established by the regulatory body. These safety objectives and safety requirements will themselves be founded on the existing knowledge as represented by the technological developments in all pertinent fields. Decisions of the regulatory body should reflect professional judgment by technically competent persons on the bases of requirements and operational experience throughout the review and assessment process.

Review and assessment includes consideration of normal operation and failures, faults, and events, including human errors that have the potential for causing the exposure of workers or the public or subjecting the environment to radiation hazards. This safety analysis is as complete as possible and one of the initial tasks of the review and assessment is to confirm its completeness. The review and assessment process includes checks on the actual situation at the site and elsewhere to validate the claims made in the submissions. Operators often have external peer reviews conducted for them by national or international organizations. The results of such reviews, if available, could provide the regulatory body with additional insight to the activities of the operator. Slide1

1.5       Quality Assurance in the Review and Assessment Process:

The regulatory body has a system to audit, review and monitor all aspects of its review and assessment process to ensure that it is being carried out in a suitable and efficient manner and that any changes to the process made necessary owing to improvements in knowledge or techniques or otherwise are implemented.

1.6        Topics to be covered by Regulatory Review and Assessment:

Here is a list of topics that are considered part of the review and assessment process throughout the life-cycle of the facility from site selection to decommissioning:

1.6.1            Physical nature of the facility and its environment:

The following information on the facility and the process conducted are provided by the operator at various stages and used as a basis for review and assessment:

  • Detailed description of the facility, supported by drawings of the layout, the system and the equipment;
  • Information about the functional capability of the facility, its systems and major items of equipment;
  • The findings of tests which validate the functional capability;
  • The results of inspections of components;
  • Maintenance records;
  • Description of the present physical condition of SSCS based on inspections or tests;
  • Description of the support facilities available both on and off the site, including maintenance and repair shops;
  • Geological, hydrogeological and meteorological conditions; and
  • Description of off-site characteristics, including population densities, land use, industrial developments and transportation arrangements (such as airports, and road and rail systems).       Infrastructural aspects

Throughout the lifetime of any facility, operators propose and implement arrangements for waste management. The regulatory body reviews and assesses proposals for onsite treatment and storage to ensure that the processed waste and waste packages are compatible with national strategy, relevant waste acceptance requirements for subsequent waste management steps and regulatory requirements. Specifically, the regulatory body assures itself that the waste or waste packages:

  • Are properly characterized and compatible with the anticipated nature and duration of storage pending disposal;
  • Can be subjected to regular surveillance; and
  • Can be retrieved for further waste management steps.

Transport of radioactive materials and waste and equipment both on and off the site needs adequate arrangements. The regulatory body reviews and assesses these arrangements and assures itself that all national and regulatory requirements are met.    Safety analysis:

Throughout the lifetime of the facility, the regulatory body reviews and assesses the information provided by the operator on the facility, in particular the information covering:

  • A compilation of the safety analysis and its assumptions;
  • Structures, systems and components important to safety;
  • Limits and permitted operational states;
  • Anticipated operational occurrences;
  • Postulated initiating events for the safety analyses, such as external hazards, internal faults and internal hazards;
  • Description how defence in depth concept is fulfilled;
  • Analytical methods and computer codes used in the safety analysis and verification and validation of such codes;
  • Radioactive releases and radiation exposures under normal operation and fault conditions; and
  • The operator’s safety criteria for analyses of operator action, common cause events, cross-link effects, single failure criterion, redundancy, diversity and separation.

The impact of the facility is assessed and social and economic issues, land use issues, technical issues such as detailed considerations of geology and hydrogeology, transport routes and protection of the environment are taken into account. Both the anticipated impact and the consequences of fault conditions which are the subject of safety analysis are considered.

1.6.2           The operating organization and the management system

At all stages of the facility’s lifetime, the operator demonstrates that:

  • It will be in control of the facility;
  • It has an adequate safety management system to be able to manage and control the facility; and
  • It has resources available to meet its obligations and liabilities in connection with an authorization.

The information that the operators provide to the regulatory body for review and assessment include:

  • The structure of the operator’s organization, showing that it has adequate control of the activities of its own staff and its contractors;
  • A demonstration of adequate resources for appropriately trained and experienced staff, ensuring in-house expertise;
  • Demonstration of the adequacy of the procedures for control of changes to organizational structure and resources;
  • The specification and documentation of the duties of staff, demonstrating integration of safety responsibilities into their duties;
  • Demonstration of the provision or access to a high level of expertise in safety to carry out safety and engineering analysis, and associated audit and review functions;
  • Demonstration of the adequacy of the provisions for financing continuing liabilities
  • and decommissioning; and
  • Any proposals for the use of contractors.

The operator demonstrates an overall safety management system whereby all activities are controlled to provide an assurance that requirements for quality, safety and the environment are met. This includes having operational procedures.

The operator demonstrates that it has:

  • A mechanism for setting of operating and safety targets;
  • A policy that states that safety takes precedence over production;
  • Documented roles and responsibilities of individuals and groups;
  • Procedures for control of modifications to the facility;
  • Procedures for the feedback of experience to the staff, including the experience relating to organizational and management failures;
  • Mechanisms for maintaining the configuration of the facility and its documentation;
  • Formal arrangements for employing and controlling contractors;
  • Staff training facilities and programmes;
  • A quality assurance programme and regular quality assurance audits with independent assessors;
  • A system for ensuring compliance with regulatory requirements;
  • Comprehensive, readily retrievable and auditable records of baseline information, operational and maintenance history;
  • Staffing levels for the operation of the facility that take account of absences, shift working and overtime restrictions;
  • Qualified staff available on duty at all times;
  • Systematic and validated methods for staff selection (e.g. testing for aptitude,
  • knowledge and skills);
  • Programmes for initial, refresher and upgrade training, including the use of simulators;
  • Training in safety culture, particularly for managers;
  • Competence requirements for operation, maintenance, and technical and managerial staff;
  • Programmes for feedback of operating experience relating to failures in human performance;
  • Guidelines on fitness for duty in relation to hours of work, health and substance abuse;
  • Competence requirements for operation, maintenance, and technical and managerial staff; and
  • A system for consideration of the human-machine interface and design and for the analysis of human information requirements and task workload for the control room and other work stations.

1.6.3       Operational procedures:

The operator demonstrates it has:

  • Formal approval and documentation for all safety related procedures;
  • A formal system for modification of a procedure;
  • Understanding and acceptance of the procedures by management and on-site staff;
  • Verification that the procedures are followed;
  • Procedures that are adequate in comparison with international good practice;
  • Arrangements for regular review and if necessary, revision of the procedures;
  • Clear procedures taking into account human factor principles;
  • Procedures which comply with the assumptions and findings of the safety analysis, design and operating experience; and
  • Adequate emergency operating procedures.    Equipment qualification:

The operator provides:

  • A list of equipment covered by the equipment qualification programme and a list of control procedures;
  • A qualification report and other supporting documents (such as equipment qualification specifications, qualification plan);
  • Verification that the installed equipment matches the qualification requirements;
  • Procedures to maintain qualification during the installed life of the equipment;
  • Information on mechanisms for ensuring compliance with these procedures;
  • Documentation on maintenance, testing and inspection programme and a feedback procedure to ensure that ageing degradation of qualified equipment remains insignificant;
  • Documentation on an analysis of the effect of equipment failure on other equipment qualification and appropriate corrective actions to maintain equipment qualification;
  • Information on protection of qualified equipment from adverse environmental conditions;
  • Information on the physical integrity and functionality of qualified equipment; and
  • Records of all qualification measures taken during the installed life of equipment.    Management of ageing:

The operator provides an appropriate programme for the management of ageing of equipment that covers:

  • Documented methods and criteria for identifying SSCs covered by the ageing management programme;
  • A list of SSCs covered by the ageing management programme and records which provide information to support the management of ageing;
  • An evaluation and documentation of potential ageing degradation that may affect the safety functions of SSCs;
  • Details of the extent of understanding of dominant ageing mechanisms of SSCs;
  • Details of the programme for timely detection and mitigation of ageing processes and/or ageing effects;
  • Acceptance criteria and required safety margins for SSCs; and
  • Awareness of physical condition of SSCs, including actual safety margins.

1.6.4       Operator’s safety performance:

The operator provides details of:

  • The system for identifying and classifying safety related incidents;
  • The arrangements for root cause analysis of incidents, the lessons learnt and follow up measures taken;
  • Methods for selecting and recording safety related operational data, including those for maintenance, testing and inspection;
  • Trend analyses of safety related operational data;
  • Feedback of safety related operational data into the operating regime including records and reports of incidents and accidents;
  • Analyses of safety performance indicators such as:
    • Frequency of unplanned termination of operation;
    • Frequency of selected safety system actuation/demands;
    • Frequency of safety system failures;
    • Unavailability of safety systems;
    • Annual individual and collective radiation doses to workers;
    • Trends in causes of failures;
    • Backlog of outstanding maintenance;
    • Extent of preventive maintenance;
    • Extent of corrective maintenance including repair and replacement;
    • Frequency of unplanned operator actions in the interest of safety and their success rate;
    • Amounts of radioactive waste generated; and
    • Quantities of radioactive waste in storage.
  • Records of radiation doses to persons on site;
  • Records of off-site contamination and radiation monitoring data for the site;
  • Records of quantities and relevant characteristics of radioactive waste generated and stored in the facility; and
  • Records of the quantities of radioactive effluents discharged.

1.6.5       Experience from other facilities and research findings:

The operator provides information of its arrangements for:

  • Feedback of experience relevant to safety from similar facilities and other nuclear and non-nuclear facilities;
  • Assessment of and actions on the basis of the above experience;
  • Determining the need for research and development;
  • The receipt of information on the findings of relevant research programmes;
  • Assessment of and actions on the research information.

The remaining material on the subject will be covered under Chapter 41.


  1. NEA Improving Nuclear Regulatory Effectiveness;
  2. IAEA The Safety of Nuclear Installations; and
  3. IAEA Regulatory Control of Nuclear Power Plants.

Chapter 41