Maintenance and repairs of Czechoslovak nuclear power plants - present state and prospects

For Czechoslovak nuclear power plants comprising four WWER-440 units it is planned that their maintenance will be ensured by 1158 staff members and backed up by 120 external suppliers (on annual average). The following repair outage periods are planned: overhaul under the letter of guarantee 70 days (in one year of operation), major type overhaul 49 days, major type overhaul involving pressure vessel diagnostics 84 days (accomplished in 20,000 hours of performance and every 4 years thereafter), minor overhaul 14 days (annually). Experience with major overhauls hitherto performed is summarized, 20 and 9 of them having been made at the Bohunice and Dukovany nuclear power plants, respectively. Costs spent on the maintenance and repair since the nuclear power unit commissioning till the end of 1988 as well as expected costs till 1995 are tabulated. The possibilities of extending the lifetime of the main components and whole WWER-440 units in Czechoslovak nuclear power plants are also briefly discussed. (Z.M.)