“We have already carried out pressure tests of the primary and secondary circuits for the pressure of 3.2 and 2.0 MPa and confirmed the integrity of these circuits. Now, we are to switch on reactor coolant pumps and carry out necessary integrity and strength tests. We must confirm that all mechanisms work routinely and later come to stages which relate to obtaining a Rostechnadzor’s license for loading nuclear fuel in the reactor,” Novovoronezh-II NPP director Vladimir Povarov explained.

Cold and hot trials are an important phase of a nuclear unit commissioning. It involves the performance testing of equipment. Trials of the overpressure protection system of the primary and secondary circuits are carried out, performance tests of reactor coolant pumps are conducted, and the reactor plant protection systems are tested. This is a last large-scale technological operation at the power unit before first criticality.

The second phase of commissioning is divided into two parts. The “cold” trials come first.  This stage will take 35 days. They are followed by “hot” trials. At this stage the start-up, adjustment and operation specialists will try four reactor coolant pumps at hot parameters (preset pressure of 16.0 MPa and coolant temperature of 280 Co) for 100 hours.

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The Generation III+ VVER-1200 reactor is constructed at Novovoronezh-II NPP Unit 2 site. It is the reference project for Rooppur NPP, built in Bangladesh. The unit provides for the highest level of operational safety and fully meets all post-Fukushima requirements. Its main feature is a combination of active and passive safety systems, which do not require the NPP personnel’s  intervention.