Design differences between Russian NPPs

Let’s look at the differences in the construction of reactors at the Japanese plant "Fukushima-1" and those that are working and are being built in Russia.

Let’s start with the technological scheme and features of the equipment.

Thus, at the nuclear power plant "Fukushima" is used single-circuit diagram of the generation of steam. Here boiling reactor used: for steam turbine generator set is generated in the reactor vessel from the water, relieving heat from the reactor core is separated, i.e. freed from water droplets and then enters the separation turbine. Water circulation through the reactor is forced by pumps.

Operating in the Russian VVER-1000 are arranged somewhat differently. Use a pair of dual-generation scheme. And applying pressure reactor: the first loop (closed is under high pressure of about 160 kgf/cm2) is water removes heat from the reactor core. Water circulates through the first loop reactor scheme — the steam generator — the reactor. Water circulation is the primary circuit pumps, which has great inertia, ensuring a while peak heat removal from the core in blackout mode. The very same steam is generated in the second loop, in the steam generators by heating the water of the primary circuit water of the second circuit. The transfer of heat and steam generation takes place in the steam generators through the pipe surface that separates the first and second circuits. The volume of water in the steam generators can be used to remove heat from the reactor in the event of power failure by its evaporation.

As for the stations being built by NPP-2006 project, the technological scheme will be similar to the current NPP with VVER-1000.

The device of the containment (containment).

On "Fukushima" is used boxed containment vessel type, reinforced concrete. The reactor vessel is placed in the inner protective metal case. In contrast to the Japanese designs on Russian VVER-1000 containment reinforced concrete lined with steel, and designed for internal and external effects of natural and anthropogenic origin. Also, the design of the containment is designed for maximum seismic action defined for the site of the NPP.

NPP-2006 project involves the use of double-reinforced concrete containment with vented through filters intershell space. The inner shell is designed for impact protection in the event of an emergency at the reactor facility (pressure, temperature, flying objects, etc.). The outer shell is designed for the perception of any external influences, including the impact of the incident plane. And of course, that this construction assumes the maximum seismic effect on the NPP site.

Security system.

On the constructed in the 1970s, "Fukushima" is not passive safety systems that do not require power for protective functions, and there is no trap melt. At existing plants with a Russian VVER-1000 provides passive safety systems — germoemkosti of the emergency core cooling system (ECCS GE), but the trap of the melt is also absent. In new nuclear power plants, such as the Baltic, the Leningrad-2, Novovoronezh-2, also has passive safety systems that do not require electrical power for protective functions (core cooling) for 72 hours, and the trap of the melt.

It should also be noted that in contrast to the Russian power (and VVER-1000 and AES-2006), on the Japanese nuclear power plant "Fukushima" is corrosion of fuel cladding in full mode. And the location of the control system and the reactor protection system (CPS) of the Japanese lower, in contrast to the Russian version (top in both cases).

More information from Rosatom on the events at Fukushima can be found here:

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