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Tuesday, March 15, 2011

Nuclear pressure water reactors are safe but the environmental crazies will continue to spew their lies about nuclear reactors as if the US was Japan



Boiling water reactor

Japan uses boiling water reactors.

The BWR was developed by the Idaho National Laboratory and General Electric in the mid-1950s. The main present manufacturer is GE Hitachi Nuclear Energy, which specializes in the design and construction of this type of reactor.

The BWR uses demineralized water as a coolant and neutron moderator. Heat is produced by nuclear fission in the reactor core, and this causes the cooling water to boil, producing steam. The steam is directly used to drive a turbine, after which it is cooled in a condenser and converted back to liquid water. This water is then returned to the reactor core, completing the loop. The cooling water is maintained at about 75 atm (7.6 MPa, 1000–1100 psi) so that it boils in the core at about 285 °C (550 °F). In comparison, there is no significant boiling allowed in a PWR (Pressurized Water Reactor) because of the high pressure maintained in its primary loop—approximately 158 atm (16 MPa, 2300 psi).

A boiling water reactor, by contrast, has only one coolant loop.

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Pressurized water reactor

Pressurized water reactor

The US uses Pressurized water reactors


Two things are characteristic for the pressurized water reactor (PWR) when compared with other reactor types: coolant loop separation from the steam system and pressure inside the primary coolant loop. In a PWR, there are two separate coolant loops (primary and secondary), which are both filled with demineralized/deionized water.

The transfer of heat is accomplished without mixing the two fluids, which is desirable since the primary coolant might become radioactive.

Pressurized water reactors (PWRs) constitute a majority of all western nuclear power plants and are one of two types of light water reactor (LWR), the other type being boiling water reactors (BWRs). In a PWR the primary coolant (water) is pumped under high pressure to the reactor core where it is heated by the energy generated by the fission of atoms. The heated water then flows to a steam generator where it transfers its thermal energy to a secondary system where steam is generated and flows to turbines which, in turn, spins an electric generator. In contrast to a boiling water reactor, pressure in the primary coolant loop prevents the water from boiling within the reactor.

Several hundred PWRs are used for marine propulsion in aircraft carriers, nuclear submarines and ice breakers. In the US, they were originally designed at the Oak Ridge National Laboratory for use as a nuclear submarine power plant.

Two things are characteristic for the pressurized water reactor (PWR) when compared with other reactor types: coolant loop separation from the steam system and pressure inside the primary coolant loop. In a PWR, there are two separate coolant loops (primary and secondary), which are both filled with demineralized/deionized water.

(After you read this information about the pwr reactors used in the US and bwr reactors used in Japan it becomes obvious that boiling water reactors are not as safe as the pwr reactors used in the US.

You would think Japan would have constructed reactors that had two coolant loops and could be controlled better like the pressure water reactors in the US. Also you would think that Japan, knowing that a major fault line was near the coast of Japan, would have built their reactors at least a few miles inland and not right on the coast where a tsunami could easily cause a reactor to fail. The island of Japan is one big fault from top to bottom.

All the green nuts will be yelling about the threat of nuclear reactors which is a lie in the US.

Nuclear pressure water reactors are very safe but the environ-mental crazies will continue to spew their lies about nuclear reactors as if the US was Japan.)
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