Unit 2 at Russia’s Leningrad II NPP (also known as Leningrad 6) has achieved first criticality and was brought to the minimum-controlled power level, nuclear utility Rosenergoatom said on 31 August.

The commissioning of the VVER 1200, which is carried out in stages, began on 19 July, when the first fuel assembly with fresh nuclear fuel was loaded into the reactor vessel, Rosenergoatom noted.

“The minimum power level will allow us to safely conduct a series of tests and verify the physical characteristics of the reactor core for compliance with the design requirements. After these operations are completed and the calculations are received by Rostekhnadzor, it remains for us to obtain a permit for power start-up and to begin a phased increase in capacity,” said Alexander Belyaev, chief engineer of Leningrad II.

According to the physical start-up programme, more than 50 tests will be carried out at the unit within a week. These studies will make it possible to clarify the neutron-physical characteristics of the first fuel load of a nuclear reactor obtained in the calculations, as well as to confirm the reliability of the functioning of protections, interlocks and the entire system of nuclear-physical control and nuclear safety of the reactor installation.

At the subsequent stages, during the power start-up, pilot operation and comprehensive testing of the power unit, equipment will undergo a final check at operating parameters, with heat and electric output, Rosenergoatom said.

Commercial operation of Leningrad II unit 2 is scheduled for 2021. It will replace the RBMK-1000 reactor at unit 2 of the Leningrad NPP, which has operated for 45 years.

Photo: Leningrad II-2 reached minimum controlled power level (Credit: Rosatom)