Results of ageing studies generally points out that rotating machines (motors, motor generator sets, turbo-Generators may become more maintenance intensive. A systematic study of such rotating machines has thus become part of PLiM. Long term operation of plant may require replacement of some of these to assure long term safety and reliable operation.

1.8.1. CONTROL, INSTRUMENTATION EQUIPMENT OBSOLESCENCE AND COMPUTER SYSTEM UPGRADES

It is not possible to follow a uniform policy on ageing management of control & instrumentation for a nuclear power plant. Hence individualized approaches are to be determined for different cases.

Early HWRs were designed with a mixture of computers for direct digital control of the major plant systems as well as analogue electronic instrumentation and control equipment, most of which is not expected to last the 30-60 year range of operating life. Moreover, the issue of C&I equipment obsolescence is considered of high importance due to lack of original equipment vendors, rapid electronic technology development, and replacement of process control analogue instruments with digital electronics.

For HWR LTO, a systematic approach to identify/deal with obsolete equipment and a long range plan to address instrument obsolescence is recommended. Normally these issues are being dealt with for attending to PLiM for life attainment as well.