On 1 September 2018, at Novovoronezh NPP-2 Unit 2, the hot stage of the equipment hot & cold break-in procedure was initiated. This is the last essential commissioning stage, after which the first criticality is attained.
This major commissioning stage precedes the first criticality, and its purpose is to verify that the unit operation is safe and secure. Adequate performance of the main and auxiliary reactor plant equipment/systems is verified in operational modes and at operational parameters.
Previously, at the cold break-in stage, 68 positive thermohydraulic tests of the unit's equipment and systems were ran. The next stage, a minor revision of the main equipment, took 15 days. Additionally, thermal insulation was installed, and the equipment was prepared for commissioning works.
"During the hot break-in, we are planning to run 144 tests using hot water,” says Vladimir Kazansky, Deputy Chief Engineer of the new Novovoronezh NPP-2 Units. "As per the commissioning works schedule, the hot stage will last about 50 days; it comprises a break-in of the four main circulation pumps in hot conditions (a coolant temperature of 280°C and a pressure of 16.0 MPa), checkup of the auxiliary power supply systems, blowing of the main steam circuits with own steam, comprehensive testing of the reactor's safety, control and protection systems. The testing will run step by step to ensure that the unit can operate safely and securely throughout the lifecycle."
Once the equipment hot break-in is successfully completed, the innovative generation 3+ power unit will be ready to attain its first criticality.
Innovative generation 3+ power units operate with absolute reliability and feature enhanced performance feasibility. The unit design comprises state-of-the-art solutions. The most prominent feature of the VVER-1200 design is a unique combination of active and passive safety systems that make the plant as resistant to external and internal impacts as possible. The defining characteristic of a passive safety system is that it is designed to operate without power and/or human intervention. Specifically, a unit equipped with a VVER-1200 reactor will feature the following systems: The core catcher, a device designed to contain molten nuclear reactor cores; the Passive Heat Removal System (PHRS) that can continuously remove heat from the reactor core to the atmosphere via the steam generators whenever no power sources are available, etc.