Management of reactor pressure vessel irradiation embrittlement at the Loviisa nuclear power plant

At the Loviisa nuclear power plant, irradiation embrittlement of the reactor pressure vessel was found to be much higher than expected. Most of the measures available to reduce the neutron dose to the reactor pressure vessel and to soften thermal shock transients were taken. A utility has been prepared for the annealing of the RPV of Unit 1 in 1996. The new research programmes to support the annealing processes are focused on consistent and improved neutron dose estimates and on creation of annealing and re-embrittlement databases. The amount of the original surveillance material, especially of welds, being limited, every effort was made to utilize the available material as effectively as possible. 4 refs