Energy amplifier

From Wikipedia, the free encyclopedia

In nuclear physics, an energy amplifier is a novel type of nuclear power reactor, a subcritical reactor, in which an energetic particle beam is used to stimulate a reaction, which in turn releases enough energy to power the particle accelerator and leave an energy profit for power generation. The concept has more recently been referred to as an accelerator-driven system (ADS).

Contents 1 History 2 Principle and feasibility 3 Advantages 4 Disadvantages 5 See also 6 References 7 External links

[edit] History

The concept is credited to Carlo Rubbia, a nuclear physicist and former director of Europe's CERN international nuclear physics lab. He published a proposal for a power reactor based on a proton cyclotron accelerator with a beam energy of 800 MeV to 1 GeV, and a target with thorium as fuel and lead as a coolant.

[edit] Principle and feasibility

The energy amplifier uses a synchrotron accelerator to produce a beam of protons. These hit a heavy metal target such as lead, thorium or uranium and produce neutrons through the process of spallation. It might be possible to increase the neutron flux through the use of a neutron amplifier, a thin film of fissile material surrounding the spallation source.^[1] A discussion of neutron amplification in CANDU reactors can be viewed at^[2] while CANDU is a critical design, many of the concepts can be applied to a sub-critical system. Thorium nuclei absorb neutrons, thus breeding fissile uranium-233, an isotope of uranium which is not found in nature. Moderated neutrons produce U-233 fission, releasing energy.

This design is entirely plausible with currently available technology, but requires more study before it can be declared both practical and economical.

[edit] Advantages

The concept has several potential advantages over conventional nuclear fission reactors:

• Subcritical design means that the reaction could not run away — if anything went wrong, the reaction would stop and the reactor would cool down. A meltdown could however occur if the ability to cool the core was lost.
• Thorium is an abundant element — much more so than uranium — reducing strategic and political supply issues and eliminating costly and energy-intensive isotope separation. There is enough thorium to generate energy for at least several thousand years at current consumption rates.
• The energy amplifier would produce very little plutonium, so the design is believed to be more proliferation-resistant than conventional nuclear power (although the question of uranium-233 as nuclear weapon material must be assessed carefully).
• The possibility exists of using the reactor to consume plutonium, reducing the dangerously large world stockpile of the very-long-lived element.
• Less long-lived radioactive waste is produced — the waste material would decay after 500 years to the radioactive level of coal ash.
• No new science is required; the technologies to build the energy amplifier have all been demonstrated in the laboratory. Building an energy amplifier requires only some engineering effort, not fundamental research (unlike nuclear fusion proposals).
• Power generation might be economical compared to current nuclear reactor designs if the total fuel cycle and decommissioning costs are considered.
• The design could work on a relatively small scale, making it more suitable for countries without a well-developed power grid system
• Inherent safety and safe fuel transport could make the technology more suitable for developing countries as well as in densely populated areas.

[edit] Disadvantages

• General technical difficulties.
• Each reactor needs its own facility (synchrotron) to generate the high energy proton beam, which is very costly.
• No synchrotron of sufficient power (> ~12 MW) has ever been built. Currently, the Spallation Neutron Source utilizes a 1.44 MW proton beam to produce its neutrons, with upgrades envisioned to 5 MW.^[3]

[edit] See also

Breeder reactor, another type of nuclear reactor that aims for an energy profit by creating more fissile material than it consumes.

[edit] References

[edit] External links

• New Age Nuclear: article on energy amplifiers | Cosmos Magazine