Overview

At the end of 2003 there were 273 research reactors in operation worldwide, about 87% of them are more than 20 years old and 66% are more than 30 years old. Of these 273 research reactors, 205 have a power level below 5 MW and are considered as low power research reactors. This limit is, however, arbitrary and other classifications according to reactor power do exist (i.e. < 2 MW is Low Power in the USA). As these facilities age, equipment or components may begin to fail more frequently as they reach or exceed their original, expected lifetime. Many facility Safety Analysis Reports and procedures as originally written do not cover aspects of plant age. Hence, unanticipated problems caused by historically poor maintenance or slow corrosion rate processes can cause rapid and catastrophic failure modes. A good example of this occurred in 2004 at a nuclear power plant in Japan. This particular nuclear facility had a non-nuclear system steam pipe that had not been on a preventative maintenance and inspection program. The steam pipe unexpectedly ruptured, killing four people. This particular pipe had not been inspected for 28 years and failed due to corrosion.

It is obvious that careful maintenance and periodic in-service inspections of the research reactor components have a positive influence on the technical state of the reactor and may extend its lifetime considerably. Reactor facility life extension is best accomplished by establishing and complete maintenance program at an early stage in the facility’s operation. However, high quality routine maintenance of reactor safety systems and operation within the established technical specifications is also essential to ensure the safety of the reactor and the public.

All operating reactor facilities are expected, by technical specifications, to have some form of preventative or corrective maintenance schedule. This training module may be used to extend the existing maintenance program to other, essential or non-essential facility systems. It may also provide guidance to those facilities that require an improved maintenance program.

Without question, all facilities must establish and follow some level of quality assurance and quality control with regard to facility maintenance. These maintenance programs may consist of

  • following written, established and approved procedures

  • establishing and following a periodic preventative maintenance program

  • establishing and following procedures for upgrades or repairs of the facility equipment that include a review of the repair to insure the facility remains as described in the final safety analysis report or the changes do not constitute a reduction in the original safety analysis or margins

  • an audit or review system to routinely evaluate if the above items are being performed

Learning Objectives

  1. Understand the concept of failure rate and the postive effects a routine preventative maintenace and inspection program has on the failure rate or lifetime of facility equipment
  2. Become familiar wtih various non-standard inspection or maintenance tools not considered in the original facility design that may be required as the facility ages
  3. Develop a facility maintenance program using the example maintenace documentation as guidance