Energy Multiplier Module: Difference between revisions

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{{Advert|date=April 2012}}

The '''Energy Multiplier Module''' ('''EM²''' or '''EM squared''') is a [[nuclear fission]] power [[Nuclear reactor technology|reactor]] under development by [[General Atomics]].<ref>{{cite news |title=JENKINS: Hot young prospect to replace old San Onofre reactors |author=Logan Jenkins |url=http://www.sandiegouniontribune.com/sdut-jenkins-hot-young-prospect-to-replace-old-san-2013jan10-story.html |newspaper=San Diego Union Tribune |date=10 January 2013 |accessdateaccess-date=19 January 2013}}</ref> It is a fast-neutron version of the [[Gas Turbine Modular Helium Reactor]] (GT-MHR) and is capable of converting [[spent nuclear fuel]] into electricity and industrial process heat.<ref>{{cite news|url=http://www.signonsandiego.com/news/2010/feb/24/company-has-plan-for-small-reactors/|title=Company has plan for small reactors|last=Freeman|first=Mike|date=Feb 24, 2010|work=[[San Diego Union Tribune]]}}</ref>

==Design specifications==

EM2 is an advanced modular reactor expected to produce 265 MW_e (500 MW_th) of power with evaporative cooling (240 MW_e with dry cooling) at a core outlet temperature of {{convert|850|°C|-2}}. The reactor will be fully enclosed in an underground containment structure for 30 years without requiring refueling.<ref>{{cite web|url=http://www.ga.com/advanced-reactors |title=Advanced Reactors |publisher=General Atomics |accessdateaccess-date = Feb 19, 2018}}</ref> EM2 differs from current reactors in that it does not use water coolant but is instead a [[gas-cooled fast reactor]], which uses [[helium]] as a coolant for an additional level of safety. The reactor uses a composite of [[silicon carbide]] as a fuel cladding material, and [[zirconium]] silicide as [[neutron reflector]] material. The reactor unit is coupled to a direct-drive helium [[gas turbine]] which in turn drives a generator for the production of electricity.

The nuclear core design is based upon a new conversion technique in which an initial “starter” section of the core provides the [[neutrons]] to convert fertile material (used nuclear fuel, thorium or [[depleted uranium]]) into burnable [[fissile]] fuel.<ref>“With Disposal Uncertain, Waste Burning Reactors Gain Traction – EM2 to Burn LWR Fuel,” Nuclear New Build Monitor, March 15, 2010</ref> First generation EM2 units use enriched uranium starters (approximately 15 percent [[U235]]) to initiate the conversion process.<ref>{{Cite journal |last = Choi |first = H. |title = A Compact Gas-Cooled Fast Reactor with an Ultra-Long Fuel Cycle |journal = Science and Technology of Nuclear Installations |volume = 2013 |pages = 1–10 |doi = 10.1155/2013/618707 |year = 2013 |doi-access = free }}</ref> The starter U235 is consumed as the fertile material is converted to fissile fuel. The core life expectancy is approximately 30 years without refueling or reshuffling the fuel.

Substantial amounts of usable fissile material remain in the EM2 core at the end of life. This material can be reused as the starter for a second generation of EM2s, without conventional reprocessing.<ref>{{cite web|url=http://www.ga.com/advanced-reactors |title=Advanced Reactors |publisher=General Atomics |accessdateaccess-date = Feb 19, 2018}}</ref> There is no separation of individual heavy metals required and no additional [[enriched uranium]] needed. Only [[fission products]] would be removed, which would decay to near-background radiation levels in about 500 years compared to conventional spent fuel, which requires about 10,000 years.<ref>{{Cite journal |last = Choi |first = H. |title = A Compact Gas-Cooled Fast Reactor with an Ultra-Long Fuel Cycle |journal = Science and Technology of Nuclear Installations |volume = 2013 |pages = 1–10 |doi = 10.1155/2013/618707 |year = 2013 |doi-access = free }}</ref>

All EM2 heavy metal discharges could be recycled into new EM2 units, effectively closing the [[nuclear fuel cycle]], which minimizes [[nuclear proliferation]] risks and the need for long-term repositories to secure nuclear materials.

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==Nuclear safety and security==

EM2 utilizes passive safety systems designed to safely shutdown the reactor in emergency conditions using only gravity and natural convection.<ref>{{cite web|url=http://www.ga.com/advanced-reactors |title=Advanced Reactors |publisher=General Atomics |accessdateaccess-date = Feb 19, 2018}}</ref> Control rods are automatically inserted during a loss-of-power incident via gravity. Natural convection flow is used to cool the core during whole site loss of power incidents. No external water supply is necessary for emergency cooling. The use of silicon carbide as fuel cladding in the core ensures no hydrogen production during accident scenarios and allows an extended period of response when compared to Zircaloy metal cladding used in current reactors.

Underground siting improves safety and security of the plant against terrorism and other threats.