The first (passive) stage of the technological systems spill over an open reactor has been completed at the Leningrad NPP 1st power block: the pipelines have been fully verified, starting with the pressure compensating valve and the four emergency core cooling system’s accumulators up to the reactor.

“Initially, this equipment was filled in with chemically demineralized water using the standard utility pumps. Afterwards, the pressure in the emergency core cooling system tanks increased up to 3 kgf. Then, once the latches at the cooling system’s accumulators opened, the water started to flow under the head into the reactor’s unit, thus purifying the emergency pipelines. The pressure compensating valve’s surge line was spilled by gravity”, said Vitaliy Shutikov, the head of the Leningrad NPP reactor shop.

The head of the reactor shop’s shift controlled by the head of the block’s shift managed all transitions remotely step-by-step using the block control unit, where all the necessary technological parameters were tracked, such as the pressure and the accumulator levels. The adjustment organization’s staff organized all program activities and controlled the whole process at both the block control unit and at the central hall.


“A spill over an open reactor is an important step in launching an NPP operational. It aims at verifying that the pipelines connecting the first circuit equipment are passable and do not contain any foreign objects. Besides, those pipelines are to be cleaned from any mechanical impurities, such as sand or cinder. The operation we’ve had today has confirmed that the pipelines were installed in a proper way. I deem those examinations to be successful”, said Vladimir Pereguda, the Leningrad NPP director. Also, he added that the spill procedures is undertaken pursuant to the pre-approved programs and schedules and is related to the preparations for the next step – A1. During that, individual trials and equipment testing will take place.

During the spill, several samples of the water passing through the pipelines into the reactor were taken and sent to the Leningrad NPP chemical laboratory for further analysis. Upon its completion, there will be a summary on whether the security system pipelines’ cleaning water complies with the “transparency” criteria and whether it contains any mechanical impurities.

Shortly, the second (active) spill stage is to start, during which 12 emergency pumps and two makeup and boron control system pumps are to be trialed, with the main coolant pipeline’s loops and its connectors with the emergency systems to be washed and verified. The technological systems spill over an open reactor is scheduled to be completed by the end of the month.

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.


Leningrad  NPP Information and Public Relations Administration.