Operational Limits and Conditions

Operational limits and conditions form an important part of the basis on which operation is authorized and as such should be incorporated into technical and administrative arrangements which are binding on the operating organization. 

While all operations can be directly or indirectly related to some aspect of safety, the aim of operational limits and conditions should be to manage and control the basic safety hazards in those facilities, and they should be directed toward  

Personnel direcdy responsible for the interim spent fuel storage fecility operation shall be thoroughly familiar with the facility s operational limits and conditions to ensure compliance with their provisions. Systems and procedures shall be developed in accordance with quality assurance arrangements so that an operating organization shall be able to demonstrate compliance with the operational limits and conditions. 

Operational limits and conditions for a spent fuel storage facility should be based on  

Table IV shows examples of technical operating limits and conditions which may be required for interim spent fuel storage facilities. In addition. Ref. [9], Chapter 3, should also be consulted. 

A set of OLCs important to reactor safety, including safety limits, safety system settings, limiting conditions for safe operation, requirements for inspection, periodic testing and maintenance and administrative requirements, shall be established and submitted to the regulatory body for review and assessment. 

The OLCs shall be used to provide the framework for the safe operation of the research reactor. OLCs shall be prepared for each stage in the lifetime of the reactor (e.g. commissioning and operation). The operating staff shall adhere to the OLCs throughout the lifetime of the reactor. 

The OLCs shall be adequately selected, clearly established and appropriately substantiated (e.g. by clearly stating for each OLC its object, its applicability and its specification i.e. its specified limit and its basis). The selection of and the values for the OLCs shall be based on the SAR, on the reactor design or on aspects relating to the conduct of operations, and shall be demonstrably consistent with the SAR, which reflects the present status of the reactor. 

Safety limits shall be set to protect the integrity of the physical barriers that protect against the uncontrolled release of radioactive material. For many research reactors, the first and principal physical barrier is the cladding of the fuel material. For others, the principal physical barrier is the primary coolant boundary. 

Safety limits shall be set on such important parameters as the temperature and other measured process variables that may affect the integrity of the barrier and which can be readily measured and controlled. 

The results of the analyses shall be compared with the appropriate acceptance criteria. It should be shown that the criteria discussed in paras 217-219 have been met. An evaluation of the results should demonstrate that the design is acceptable and should confirm the validity of the operational limits and conditions discussed in Chapter A. 17 (Operational Limits and Conditions). 

This chapter of the SAR shall contain the operational limits and conditions (OLCs) important to safe reactor operation which have been derived from the safety analysis. The OLCs represent an envelope of parameters, developed by the operating organization, which will protect the reactor, the staff, the general public and the environment from undue exposure if they are not exceeded. Therefore, it is essential that the OLCs are understood by the responsible operating personnel. The OLCs include safety limits, safety system settings, limiting conditions for safe operation, and surveillance and administrative requirements. Additional information is contained in paras 601-608 of Safety Series No. 35-S2. 

The OLCs are based on an agreement between the reactor operator and the regulatory body and form an important part of the requirements for authorization of the operation of the facility by the regulatory body. Changes to the OLCs shall require a revision of the SAR and assessment and approval by the regulatory body. 

Because of the important role of the OLCs in safe operation, each OLC must be selected and appropriately substantiated by a written statement of the reason for its adoption. This information shall either be presented in a sq arate document or included in this chapter of the SAR. In the first case, the information on the OLCs given in the SAR could be a sununary of this separate document. In both cases, the information on each OLC should cover the following points  

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A. 19. Operating procedures. A sampling review of operating procedures should be performed, including all the procedures for normal operations, anticipated operational occurrences and accident conditions. Inspections should be focused on the operating personnel s adherence to procedures, including operational limits and conditions. The usability and adequacy of the procedures should also be evaluated. This may necessitate sustained observations in the control room. The inspection programme in this area may necessitate sustained observation to cover 24 hour operation as necessary, in particular shift turnovers. The inspectors should check the availability of safety systems and the presence of alarm systems, and the way in which they are handled by the operations staff... 

The objectives of the surveillance progranune are to maintain and improve equipment availability, to confirm compliance with operational limits and conditions, and to detect and correct any abnormal condition before it can give rise to significant consequences for safety. The abnormal conditions which are of relevance... 

Maintenance, surveillance and in-service inspection have a common objective, which is to ensure that the plant is operated in accordance with the design assumptions and intent, and within the operational limits and conditions. Maintenance, for example, should always be followed by a series of tests. Results of surveillance or in-service inspection should be compared with the acceptance criteria. If the results fall outside the acceptance criteria, corrective actions should be initiated. Such actions should include corrective maintenance measures such as adjustment, repair or replacanent of defective items to prevent recurrence. These activities should be planned and co-ordinated effectively. A conunon database should be established in order to share relevant data and evaluations of results among the organizations that are involved in the planning and implementation of MS I activities. 

In planning activities for MS I that involve the removal from service of SSCs important to safety, it should be ensured that operational limits and conditions and any other applicable regulatory requirements are always met. If tasks for MS I are discovered to be incompatible with existing operational limits and conditions, then, after invoking the plant modification procedure, either a temporary waiver of or a permanent change to the operational limits and conditions should be effected (see also Ref [3]). 

Implementation of MS l often calls for a temporary change in the plant configuration required for normal operating conditions. In such cases the risks associated with a particular plant configuration should be assessed and the conditions for safe implementation specified prior to the performance of MS I. The conditions for safe implementation of MS l should be part of the operational limits and conditions. 

Procedures should state clearly the operating conditions necessary dnring the performance of MS I activities. These conditions should be such that the activities result neither in the violation of operational limits and conditions nor in the loss, even temporarily, of one or more complete safety functions (see also Ref. [3]). If a component of a protective system is taken out of service — for surveillance purposes, for example — the corresponding safety circuit should be left in the configuration most conducive to safety. 

The work control system should be used to ensure that plant equipment is released from service for maintenance, testing, surveillance and in-service inspection only upon authorization of designated operating personnel and in compliance with the operational limits and conditions. It should also ensure that, following maintenance, testing, surveillance and in-service inspection, the plant is returned to service only upon completion of a documented check of its configuration and, where appropriate, of a functional test. 

In compliance with the fourth item of para. 9.2, an appropriate surveillance requirement should be established for each operational limit and condition (for further information regarding operational limits and conditions, see Ref [3]). 

In preparing and reviewing the surveillance programme, special attention should be paid to ensuring that, whenever surveillance tests are carried out, control of the plant configuration is maintained and sufficient redundant equipment remains operable, even when the plant is shut down, to ensure that no operational limits and conditions are violated. 

When special tests or experiments which are not included in the snrveiUance programme or which are not performed frequently are considered necessary, these tests or experiments should be justified. A special procedure for each test should be prepared and subjected to an independent review and assessment by qualified persons other than the originator of the proposal, in order to ensure that neither the operational limits and conditions nor the design basis will be violated and that no unsafe conditions will arise. 

INTERNATIONAL ATOMIC ENERGY AGENCY, Operational Limits and Conditions and Operating Procedures for Nuclear Power Plants, Safety Standards Series No. NS-G-2.2, IAEA, Vienna (2000). 

Deviations where operational limits and conditions are not exceeded and which are properly managed in accordance with adequate procedures. Examples include a single random failure in a redundant system discovered during periodic inspections or tests, a planned reactor trip proceeding normally, spurious initiation of protection systems without significant consequences, leakages within the operational limits, minor spreads of contamination within controlled areas without wider implications for safety culture. 

AR66 Operational limits and conditions and operating procedures for nuclear power plants, NS-G-2.2, 19 December 2000. 

Will the failure or degradation of the component, system or structure during reactor operation place the reactor operation outside the boundaries of the operational limits and conditions of the reactor licence ... 

SG-O2 In-Service Inspection for Nuclear Power Plants (1930) 50-5G-O3 Operational Limits and Conditions for Nuclear Power Plants (1979)... 

See Ref. [13] for a general discussion on operating limits and conditions and their correlation with design safety. 

Measurement of hot channel factors (as allowed by facility design and operational limits and conditions) and effects of control rod positions on nuclear instrument indications. 

Normal operation is defined as plant operation within specified operational limits and conditions. Examples include starting up and shutting down the plant, normal power operation, shutdown, maintenance, testing and refuelhng. 

The topic of EOPs has been addressed in a number of IAEA safety publications, including the revised IAEA Safety Standards Series, in particular safety requirements on the operation of nuclear power plants, operational limits and conditions, and operating procedures. These publications can be partially used as a basis for the development and review of EOPs. However, it was felt that a manual that would comprehensively cover all aspects of the implementation and review of EOP development programmes, that would rely on state of the art experience and that would be applicable to various reactor technologies, was needed. This need was further justified because several Member States were organizing IAEA missions and workshops to discuss and review the completeness and quality of their EOPs. The proposal to develop a corresponding reference publication was also supported at several IAEA workshops organized on this topic. 

Normal operation. Operation within specified operational limits and conditions. 

All modifications shoirld be considered and classified according to their significance for safety. Those of the highest safety significance may need to be submitted to the regulatory authority, in particular those modifications that would alter previously approved operational limits and conditions. 

Operational Limits and Conditions and Operating Procedures for Nuclear Power Plants... 

OPERATIONAL LIMITS AND CONDITIONS AND OPERATING PROCEDURES FOR NUCLEAR POWER PLANTS... 

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