PNPI  
National Research Center "Kurchatov Institute"
Petersburg Nuclear Physics Institute

NEUTRON RESEARCH DEPARTMENT

Petersburg Nuclear Physics Institute
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7th International Workshop "Ultra Cold & Cold Neutrons. Physics & Sources." 8-14 of June 2009
 PIK reactor
About PIK 2011 (File PDF)
PIK High-Flux Reactor
Hydrogen isotope
  separation (File PDF)

Safety

  The safety



    The PIK reactor meets the most strict requirements for the modern atomic power stations. After the Chernobyl catastrophe the project was fully revised to satisfy the new safety restrictions valid in Russia.

   The core of the PIK reactor belongs to undermoderated systems - and has a negative temperature coefficient reactivity when the water density decreases. The analysis shows that due to the passive internal inherent safety of the reactor the fuel elements would not melt even under hypothetical conditions when about 1% positive reactivity is input extremely quickly (during 0,1 s).

   The PIK reactor has a 3-circuit cooling system . Due to the intermediate circuit (where the pressure is lower than that of the first and of the second circuit) the contamination of the third circuit or the environment in a case when the thermal exchangers are damaged, is fully prevented. If the destruction of the cooling system happens the reactor stops automatically. During the fast minutes the cooling is provided by means of hydroaccumulating units, after that it is provided by the pump (300 m3/s) until the core is fully cooled and unloaded. The emergency coorat Uiixture is duplicated and provides the reactor cooling even in the case of a coolant-loss accident when a circuit is broken.

   Emergency power supply is provided by three independent parallel 600 kW channels. Each channel incorporates the diesel and accumulating battery connected to one of the major circulating pumps. The work of one of the channels is sufficient to cool the reactor.

   Analysis shows that even in the case when the major part of the core is melt in an extremely short time (this situation is almost improbable), this would cause the energy output thousands times less than that of the Chernobyl catastrophe. This is due to the fact that the weight of fuel elements is considerably less (0,16 t. as compared to 200 t.), and also because of the lower melting point. This energy output is insufficient to destroy the reactor building, so all the radioactivity would be inside the building. Radioactivity accumulated in the PIK reactor would be many times lower than that of RBMK-1000 reactor - radioactivity of short-life isotopes (iodine and others) is tens times less than in the RBMK-1000, and the radioactivity of long-life ones (cesium and others) is less even hundreds times. In order to prevent the contamination outside the buildings the emergency sealing system is provided. This system permits to localize even the most improbable effluent radioactivity release and after it allows to dean the building. In addition the strengthened bulb was constructed around the reactor and its structure. This bulb is capable to withstand the shock wave up to 4 kPa.

   The above said measures permit to exclude the possibility of environmental contamination.

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