Chapter 6 contains the operating rules to maintain or recover safety functions (reactivity control, core cooling, radioactive product containment) under incident or accident conditions and revert to a safe reactor configuration.

Chapter 9 defines the routine test and inspection programme for safety-related equipment. In order to check the availability of this equipment, and notably the safeguard equipment to be used in the event of an accident, tests are periodically carried out to ensure that these systems are working properly. In the event of an unsatisfactory result, the course of action to be followed is stipulated in the technical operating specifications. This type of situation may sometimes require the licensee to shut down the reactor in order to repair the faulty equipment.

Chapter 10 finally defines the physical test programme for reactor core loads. It contains the rules defining the programme for core requalification during reactor restart and for core monitoring during reactor operations.

Secondly, there are documents describing the in-service monitoring and maintenance actions required on the equipment. On the basis of the manufacturer's recommendations, EDF defined periodic inspection programmes for the components (or preventive maintenance programmes), based on the knowledge of the potential degradation that could be suffered by the equipment.

In particular for pressurised equipment, this may entail non-destructive testing methods (radiography, ultrasounds, eddy current, dye penetrant, etc.) which are entrusted to specially qualified staff.

Owing to the gradual depletion of the fuel, reactors have to be periodically shut down so that the fuel can be renewed. At each outage, one third or one quarter of the fuel assemblies is replaced. The frequency of the outages depends on the fuel management policy.

These outages mean that parts of the installation which are normally closed off during operation become accessible. This is thus an opportunity to verify the condition of the installation by carrying out checks and maintenance as well as any scheduled modifications. Article 14 of the order of 10 November 1999 concerning monitoring of main primary and secondary system operations in particular requires that the licensee carry out periodic checks on these systems (partial and complete inspections).

There are several types of outage:

• simple refuelling outage and partial inspection outage: these outages last a few weeks and are devoted to renewing part of the fuel and conducting a limited scope programme of verification and maintenance;
• ten-yearly outage: this outage entails a wide-ranging verification and maintenance programme. This type of outage, which occurs every 10 years, is also an opportunity for the licensee to carry out major operations such as a complete inspection or a hydrotest on the main primary system, a reactor building containment test or incorporation of design changes decided on in the periodic safety reviews (see point 2.2.3).

These outages are scheduled and prepared by the licensee several months before their scheduled start date, in order to optimise the large number of tasks involved. The ASN checks the steps taken by the licensee to guarantee safety and radiation protection during the outage, and the safety of operation during the coming cycle(s).

The main points of the check carried out by the ASN concern the following:

• during the outage preparation phase, the conformity of the reactor outage programme with the applicable reference system. The ASN will give its opinion on this programme;
• during the outage - at the regular information meetings and scheduled, unannounced or post-incident reactive inspections - the handling of the problems encountered;
• at the end of the outage - when the licensee presents the reactor outage summary - the condition of the reactor and its suitability for restart. After this check, the ASN issues the criticality authorisation;
• after criticality, the results of all tests carried out during the outage and after restart.