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Encyclopedia > Supercritical water reactor
Supercritical water reactor scheme.

The Supercritical water reactor (SCWR) is a Generation IV reactor concept that uses supercritical water as the working fluid. SCWRs are basically LWRs operating at higher pressure and temperatures with a direct, once-through cycle. As most commonly envisioned, it would operate on a direct cycle, much like a BWR, but since it uses supercritical water (not to be confused with critical mass) as the working fluid, would have only one phase present, like the PWR. It could operate at much higher temperatures and pressure than both current PWRs and BWRs. Image File history File links Scwr. ... Image File history File links Scwr. ... Generation IV reactors (Gen IV) are a set of theoretical nuclear reactor designs currently being researched. ... A supercritical fluid is any substance at a temperature and pressure above its thermodynamic critical point. ... A light water reactor or LWR is a thermal nuclear reactor that uses ordinary water (as opposed to heavy water) as its neutron moderator. ... A boiling water reactor (BWR) is a light water reactor design used in some nuclear power stations. ... A sphere of plutonium surrounded by neutron-reflecting blocks of tungsten carbide. ... Pressurized water reactors (PWRs) (also VVER if of Russian design) are generation II nuclear power reactors that use ordinary water under high pressure as coolant and neutron moderator. ...


Supercritical water-cooled reactors (SCWRs) are promising advanced nuclear systems because of their high thermal efficiency (i.e., about 45% vs. about 33% efficiency for current light water reactors (LWR) and considerable plant simplification. The thermal efficiency () is a dimensionless performance measure of a thermal device such as an internal combustion engine, a boiler, or a furnace, for example. ... A light water reactor or LWR is a thermal nuclear reactor that uses ordinary water, also called light water, as its neutron moderator. ...


The main mission of the SCWR is generation of low-cost electricity. It is built upon two proven technologies, LWRs, which are the most commonly deployed power generating reactors in the world, and supercritical fossil fuel fired boilers, a large number of which are also in use around the world. The SCWR concept is being investigated by 32 organizations in 13 countries. Lightning strikes during a night-time thunderstorm. ... Fossil fuels are hydrocarbons, primarily coal and petroleum (fuel oil or natural gas), formed from the fossilized remains of dead plants and animals[1] by exposure to heat and pressure in the Earths crust over hundreds of millions of years[2]. The theory that hydrocarbons were formed from these... A boiler is a closed vessel in which water or other fluid is heated under pressure. ...

Contents

Design

Moderator

The SCWR uses water as a neutron moderator. Moderation comes primarily from the high density sub-critical water. This high-density water is either introduced from cooling tubes inserted into the core or as a reflector or moderated-part of the core. This does not cite any references or sources. ...


The neutron spectrum will be only partly moderated, perhaps to the point that the SCWR will technically become a fast neutron reactor. Shevchenko BN350 nuclear fast reactor and desalination plant situated on the shore of the Caspian Sea. ...


The advantage of using fast neutron spectrum is having higher power rating than using thermal neutron spectrum, because of high power density.


Fuel

The fuel is traditional LWR fuel. However, it is likely the SCWR will use cladding fuel element (for single fuel element, if there is a collection of fuel elements called fuel assembly) like the BWR to reduce the chance of hotspots causing local variations in core properties. Because of the SCWR operating at exceeding condition than the current experience with LWRs and LMFBRs, thus specific criteria for material especially for cladding must be developed for safe operation to maintain fuel rod integrity during abnormal transient, rated power operation as well as releasing the fission product caused by oxidation corrosion of the cladding. There are four failure mode considered for the fuel rod integrity at abnormal transient: mechanical failure, buckling collapse, over pressure damage and creep failure. Hydrogen injection is for reducing oxidation corrosion.


Coolant

The coolant will be supercritical water. Operation above the critical pressure eliminates coolant boiling, so the coolant remains single-phase throughout the system. When under extreme pressure, water does not boil and turn to steam when heated—a condition known as supercritical. That means more of the heat produced via fission can be converted into electricity in reactors cooled with supercritical water. In addition, the elements that handle water's phase change from liquid to gas in conventional light water reactors can be cut from the design. Thus, the need for recirculation and jet pumps, pressurizers, steam generators, and steam separators and dryers in current LWRs is eliminated reducing construction costs. A supercritical fluid is any substance at a temperature and pressure above its thermodynamic critical point. ... An induced nuclear fission event. ...


Control

SCWRs would likely have control rods inserted through the top, as is done in PWRs.


Material

This section describes the R&D needs for SCWR material. The actual R&D needed to select and/or develop materials that be compatible and resist under condition above condition current LWR. the R&D proposed for SCWR designs focus on following key areas:

  • Oxidation, corrosion, and stress corrosion cracking
  • Radiolysis and water chemistry
  • Strength, embrittlement, and creep resistance
  • Dimensional and microstructural stability

In addition to those performance factors, the cost of the material and its effect on fuel utilization must also be considered to meet the economic and sustainability requirements of Generation IV designs.


Advantages and disadvantages

  • Higher thermal efficiency. Supercritical water-cooled reactors (SCWRs) are promising advanced nuclear systems because of their high thermal efficiency, about 45% vs. about 33% efficiency for current light water reactors (LWR).
  • Unknown chemistry.
  • Materials constraints.
  • The need of circulation pumps, pressurizer, steam generator, steam separator and dryer can be eliminated, so Balance of Plant is considerable simple than current nuclear power plant.
  • water coolant has high specific enthalpy because coolant under supercritical condition.

The thermal efficiency () is a dimensionless performance measure of a thermal device such as an internal combustion engine, a boiler, or a furnace, for example. ... A light water reactor or LWR is a thermal nuclear reactor that uses ordinary water, also called light water, as its neutron moderator. ...

References

1: INL SCWR page'


2: INL presentation (Portable Document Format|PDF).


3: INL Progress Report for the FY-03 Generation-IV R&D Activities for the Development of the SCWR in the U.S. (Portable Document Format|PDF).


4: Generation IV International Forum SCWR website.


5: INL SCWR workshop summary (Portable Document Format|PDF).


See also

  • Reduced moderation water reactor, a concept that is in some ways similar and in others overlapping to the SCWR concept, and is under development appart from the Generation IV program.

Generation IV reactors (Gen IV) are a set of theoretical nuclear reactor designs currently being researched. ... The reduced moderation water reactor (RMWR) is a proposed type of light water moderated nuclear power reactor, featuring some characteristics of a fast neutron reactor. ... A generation III reactor is a development of any of the generation II nuclear reactor designs incorporating evolutionary improvements in design which have been developed during the lifetime of the generation II reactor designs, such as improved fuel technology, passive safety systems and standardised design. ... The Advanced Boiling Water Reactor (ABWR) is an improved design of boiling water reactor. ... The Economic Simplified Boiling Water Reactor (ESBWR) is a passively safe generation III+ reactor which builds on the success of the ABWR. Both are designs by General Electric, and are based on their BWR design. ... The Economic Simplified Boiling Water Reactor (ESBWR) is a generation III+ reactor which builds on the success of the ABWR. Both are designs by General Electric, and are based on their BWR design. ... Core of a small nuclear reactor used for research. ... Nuclear Fuel Process A graph compairing nucleon number against binding energy Nuclear fuel is any material that can be consumed to derive nuclear energy, by analogy to chemical fuel that is burned to derive energy. ...

External links

  • UW presentation: SCWR Fuel Rod Design Requirements (Powerpoint presentation).
  • ANL SCWR Stability Analysis (Powerpoint presentation).
  • INL ADVANCED REACTOR, FUEL CYCLE,AND ENERGY PRODUCTS WORKSHOP FOR UNIVERSITIES (Portable Document Format|PDF).

  Results from FactBites:
 
Supercritical water reactor - Wikipedia, the free encyclopedia (592 words)
The Supercritical water reactor (SCWR) is a Generation IV reactor concept that uses supercritical water as the working fluid.
Supercritical water-cooled reactors (SCWRs) are promising advanced nuclear systems because of their high thermal efficiency (i.e., about 45% vs. about 33% efficiency for current light water reactors (LWR) and considerable plant simplification.
Supercritical water-cooled reactors (SCWRs) are promising advanced nuclear systems because of their high thermal efficiency, about 45% vs. about 33% efficiency for current light water reactors (LWR), and considerable plant simplification.
Supercritical Water-cooled Reactor (10780 words)
The supercritical water reactor design concept is one of six chosen for further development based on the criteria of economics, safety and sustainability by the Generation-IV International Forum and is one of two selected for primary research focus in the United States.
The water used as a coolant in the reactor and the water used to provide steam to the electric turbines exists in separate closed loops that involve no discharges to the environment.
Cooling in a reactor refers to the process and medium by which heat is transferred from the reactor core to the steam supply cycle of the nuclear power plant.
  More results at FactBites »

 
 

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