Physical Calculations and Modes department

The Physical Calculations and Modes department has six units, the first and oldest of them is tasked with the performance of neutron-physical calculations for RBMK. Safety justification for the physical properties of the reactor core is carried out by the chief designer - NIKIET, but calculations are also carried out to confirm the results of their calculations. Our unit has developed special computer codes that have been accepted and certified, the results are recognized by NIKIET and the project’s supervisor is the Kurchatov Institute. All these activities are an integral part of the maintenance of the RBMK units operation, and work will continue as long as these units operate. The subject has gained particular importance, since the period of active operation of these plants is coming to an end, and the first unit of the Leningrad NPP has already been removed from the generation mode. But for RBMK units, which continue to be operated, it is necessary to carry out the adjustment of the neutron-physical characteristics taking into account changes and upgrades in the graphite piles of reactors.

Another unit is in charge of neutron-physical calculations for VVER reactors; this work has also been going on for decades. They confirm the quality of the calculations of neutron-physical characteristics for fuel loads, which are carried out by the calculation team in the nuclear safety departments at the existing nuclear power plants. Both of these units (RBMK and VVER) periodically train physicists and engineers who work at nuclear power plants and check their level of knowledge.

There is a unit that conducts experimental determination of the neutron-physical characteristics of the newly commissioned VVER units’ active zones at the commissioning stage in order to verify these characteristics for compliance with project requirements, safety standards and rules, as well as to verify the effectiveness of the control and protection system reactor plants of nuclear power units. In the near future, there are no plans to launch new units in the country (following the launch of the Leningrad NPP 6th power block), a pause is expected before the start-up and commissioning of the VVER-TOI unit at the Kursk NPP-2.

A separate unit is in charge of optimizing the operation of turbine units for VVER reactor power blocks; this work is carried out jointly with the existing nuclear power plants, Company’s departments, and manufacturers. As a result, the operating characteristics of the turbine generator are optimized, its reliability and fault tolerance are increased.

One of the units specializes in optimizing the operation of NPP units in various areas, including increasing the duration of fuel campaigns. The work is carried out jointly with many design organizations; it takes into account both the specifics of fuel operation and an assessment of the equipment reliability in the extended period between overhauls. It is necessary to conduct additional safety studies, equipment upgrades.

Another department is working on hydrogen safety. This direction has proven relevance after the accident at the Fukushima nuclear power plant. Measures were worked out in order to prevent burning and hydrogen explosion during severe accidents beyond design basis. A comprehensive hydrogen safety enhancement program has been drawn up for the Company’s NPP units, which we, as a general contractor, have been implementing for three years. New codes of calculated safety justifications are being certified, which will allow to describe in detail the processes at the VVER nuclear power plants and to evaluate countermeasures. This is the use of hydrogen-absorbing passive catalytic recombiners and other activities to avoid the combustion and explosion of hydrogen.