14.07.2017 

Circulation flushing of the reactor unit primary circuit of power unit No 1 under construction has been started at Leningrad NPP

At power unit No 1 under construction of Leningrad NPP specialists have proceeded to circulation flushing of pipelines and equipment of VVER-1200 reactor unit primary circuit.

These tests are carried out on the stage of pre-commissioning procedures when assembled systems and elements of a nuclear power plant are set to operational readiness.

Works being done on this stage are not nuclear-hazardous: circulation flushing is carried out by the turned-on circulating water pumps with fuel assembly imitators loaded into the reactor. The tests are carried out in ‘cold’ water, though it is cold only conventionally – the temperature of the primary circuit coolant is 130°С during the trials.

The Chief Engineer of Leningrad NPP under construction Aleksandr Belyaev has commented the main point of the started tests of the power unit, “We have to carry out post-assembly flushing of the primary circuit with demineralized water in order to eliminate any contamination from inner side of pipelines. Our task is to achieve almost perfectly clean water in a circuit. Its transparency must stay above 95% from feed water. This will provide system availability and the quality of operation environment.”

At the same time the specialists will test four main circulating pumps that pump the coolant through the primary circuit. To prove its working capacity the pumps will be tested in different modes and combinations, including open and closed water loops. In addition makeup and boron control system will be tested. This system is extremely important for nuclear power plant safety. It is designed to regulate physical balance of the primary circuit and concentration of boric acid in the coolant.
“In order to get a full and clear picture of the trials we control and measure almost two dozens of parameters: water temperature in the primary circuit, how fast it heats, the level of coolant, how fast pressure changes in a circuit, the maximum flow of water pumping set, coolant flow through filters, etc. In addition our specialists test the quality of collected samples from the equipment. The tests must prove that the characteristics of the main and auxiliary equipment of the primary circuit correspond to design ones, the cleanness of the first circuit is provided and the water chemistry environment in reactor room corresponds to the required level during the hot trial”, the Chief of Reactor Shop of Leningrad NPP under construction Vitaliy Shutikov has added.

The Leningrad NPP is an affiliate company for Rosenergoatom Concern OJSC. The plant is based in the city of Sosnovy Bor, 40 km to the west from Saint Petersburg at the Gulf of Finland shore. The Leningrad NPP is the first Russian nuclear power plant having RBMK-1000 reactors (uranium-graphite channel-type thermal neutron reactors). The NPP exploits 4 power blocks with the electric capacity of 1000 megawatt each. Also, pursuant to the NPP-2006 project, 1,2 VVER-1200 power blocks included into The State Atomic Energy Corporation ROSATOM long-term plan are being constructed. Rosenergoatom Concern OJSC is the owner and developer of the project. Holding TITAN-2 is the primary contractor. ATOMPROEKT is the general designer.


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