The development of a maintenance and in-service inspection schedule for a complex technical system must be based both upon certain theoretical considerations such as reliability of components, failure rates and upon practical past experience with components to be maintained. The evaluation of the facility needs may be quite complicated with several computerized databases generated. However, a facility may adequately evaluate the system components by maintaining a good written record of repairs and modification to all equipment in the facility. The procedures given below may be used by the facility over the lifetime of a component.

2.2. Theoretical Considerations

Ideally, failure data used for reliability analyses should be based on facility specific data. However, the availability of accurate facility specific data requires the expenditure of considerable resources to develop and maintain an extensive database. The collection of database source information from the field, i.e. from reactor maintenance and/or operation reports, requires a systematic approach and ongoing commitment, if the information is to be processed efficiently and if it is to be kept up to date. In addition to the need for operational and maintenance staff to provide the raw data input, a software system and analytical personnel to process the raw data are also required. Data processing primarily produces component reliability parameter statistics and trend analysis data. The reliability parameter data is often formatted so that information can interface directly with Probabilistic Safety Analysis (PSA) studies. For example, component failure rate data may be linked to a PSA specific basic event labelling format. The use of generic data by themselves will not provide an adequate data source to aid in a trend analysis of facility specific system equipment. However, generic data can still indicate whether there may be facility specific features or facility specific equipment problems that may be considerably different from that which might be predicted from international generic sources of other research reactors.

Component reliability is a function of its design, use and maintenance. Components designed for specific research reactor application (especially safety related) are usually highly reliable and should be maintained as such during their lifetime. The reliability data, however, often show variations which are related to operating conditions and practices, component application maintenance and testing practices. A brief discussion of the influence of each of these is given in 2.2.1.