Supercritical water reactor

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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 than both current PWRs and BWRs.

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 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.

Contents 1 Design 1.1 Moderator 1.2 Fuel 1.3 Coolant 1.4 Control 2 Advantages and disadvantages 3 References 4 See also 5 External links

[edit] Design

[edit] Moderator

The SCWR uses water as a neutron moderator. Moderation comes primarily from the high density subcritical 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.

[edit] Fuel

The fuel is traditional LWR fuel. However, it is likely the SCWR will use "canned" fuel elements like the BWR to reduce the chance of hotspots causing local variations in core properties.

[edit] 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.

[edit] Control

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

[edit] 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), and considerable plant simplification.

• Unknown chemistry.

• Materials constraints.

[edit] 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).

[edit] See also

• Generation IV reactor.

• Generation III reactor:
  • Advanced Boiling Water Reactor (ABWR).
  • Economic Simplified Boiling Water Reactor (ESBWR) (generation III+).

• nuclear reactor.

• nuclear fuel.

[edit] 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).

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