Reduced moderation water reactor
Encyclopedia
The Reduced-Moderation Water Reactor (RMWR), also referred to as the Resource-renewable BWR, is a proposed type of light water
moderated nuclear power reactor, featuring some characteristics of a fast neutron reactor
, thereby combining the established and proven technology of light water reactors with the desired features of fast neutron reactors. The RMWR concept builds upon the Advanced Boiling Water Reactor
and is under active development in theoretical studies, particularly in Japan
. Hitachi
and the Japan Atomic Energy Agency are both involved in research.
Even in Generation II
PWR
s, the neutron spectrum is not fully thermalised. The goal of the RMWR is to depart further from the thermal neutron spectrum in order to achieve a breeder ratio of slightly greater than one, so that after the initial fuel charge no enrichment of the uranium input to the fuel cycle is required. The RMWR concept is dependent on nuclear fuel reprocessing in order to achieve its objective of a resource renewable fuel cycle. Hitachi has proposed the FLUOREX process as reprocessing technology for this purpose, instead of the more conventional Purex
technology.
In contrast to regular light water reactors and in order to achieve a harder neutron spectrum, which is optimal for breeding purposes, the RMWR uses hexagonal fuel assemblies and Y-shaped control rods. The fuel is MOX
(Mixed Oxide), consisting of 18% plutonium
, which is surrounded by depleted uranium
in the blanket region.
The RMWR has an electric output of 1356 MWe, or 3926 MWth.
Light water reactor
The light water reactor is a type of thermal reactor that uses normal water as its coolant and neutron moderator. Thermal reactors are the most common type of nuclear reactor, and light water reactors are the most common type of thermal reactor...
moderated nuclear power reactor, featuring some characteristics of a fast neutron reactor
Fast neutron reactor
A fast neutron reactor or simply a fast reactor is a category of nuclear reactor in which the fission chain reaction is sustained by fast neutrons...
, thereby combining the established and proven technology of light water reactors with the desired features of fast neutron reactors. The RMWR concept builds upon the Advanced Boiling Water Reactor
Advanced Boiling Water Reactor
The Advanced Boiling Water Reactor is a Generation III boiling water reactor. The ABWR is currently offered by GE Hitachi Nuclear Energy and Toshiba...
and is under active development in theoretical studies, particularly in Japan
Japan
Japan is an island nation in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south...
. Hitachi
Hitachi
Hitachi is a multinational corporation specializing in high-technology.Hitachi may also refer to:*Hitachi, Ibaraki, Japan*Hitachi province, former province of Japan*Prince Hitachi and Princess Hitachi, members of the Japanese imperial family...
and the Japan Atomic Energy Agency are both involved in research.
Even in Generation II
Generation II reactor
A generation II reactor is a design classification for a nuclear reactor, and refers to the class of commercial reactors built up to the end of the 1990s...
PWR
Pressurized water reactor
Pressurized water reactors constitute a large majority of all western nuclear power plants and are one of three types of light water reactor , the other types being boiling water reactors and supercritical water reactors...
s, the neutron spectrum is not fully thermalised. The goal of the RMWR is to depart further from the thermal neutron spectrum in order to achieve a breeder ratio of slightly greater than one, so that after the initial fuel charge no enrichment of the uranium input to the fuel cycle is required. The RMWR concept is dependent on nuclear fuel reprocessing in order to achieve its objective of a resource renewable fuel cycle. Hitachi has proposed the FLUOREX process as reprocessing technology for this purpose, instead of the more conventional Purex
PUREX
PUREX is an acronym standing for Plutonium - URanium EXtraction — de facto standard aqueous nuclear reprocessing method for the recovery of uranium and plutonium from used nuclear fuel. It is based on liquid-liquid extraction ion-exchange.The PUREX process was invented by Herbert H. Anderson and...
technology.
In contrast to regular light water reactors and in order to achieve a harder neutron spectrum, which is optimal for breeding purposes, the RMWR uses hexagonal fuel assemblies and Y-shaped control rods. The fuel is MOX
Mox
MOX might be a name or acronym for:*Malaysian Oxygen Berhad - A Malaysian company that is specializes in providing total gas solutions.*Mixed Oxide Fuel, from nuclear reprocessing*An alien race in the TimeSplitters 2 video game, the Mox...
(Mixed Oxide), consisting of 18% plutonium
Plutonium
Plutonium is a transuranic radioactive chemical element with the chemical symbol Pu and atomic number 94. It is an actinide metal of silvery-gray appearance that tarnishes when exposed to air, forming a dull coating when oxidized. The element normally exhibits six allotropes and four oxidation...
, which is surrounded by depleted uranium
Depleted uranium
Depleted uranium is uranium with a lower content of the fissile isotope U-235 than natural uranium . Uses of DU take advantage of its very high density of 19.1 g/cm3...
in the blanket region.
The RMWR has an electric output of 1356 MWe, or 3926 MWth.