Energy Multiplier Module: Difference between revisions

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The '''Energy Multiplier Module''' (EM2'''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://mwww.utsandiegosandiegouniontribune.com/news/2013/jan/10/sansdut-onofrejenkins-nuclearhot-reactorsyoung-generalprospect-atomics/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 modifiedfast-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, without separative or conventional [[nuclear reprocessing]].<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>

[[File:high temperature gas cooled reactor.jpg|thumb|200px|Schematic diagram of a helium-cooled reactor with a gas turbine-generator]]

==Design specifications==

The 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}}. andThe reactor will be fully enclosed in an underground containment structure for 30 years without requiring refueling.<ref>{{Citationcite neededweb|url=http://www.ga.com/advanced-reactors |title=Advanced Reactors |publisher=General Atomics |access-date =February 2016 Feb 19, 2018}} The</ref> EM2 differs from current reactors asin 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 [[berylliumzirconium]] oxidesilicide as [[neutron reflector]] material. The reactor unit is coupled to a direct-drive helium [[closed-cycle gas turbine]] which in turn drives a generator forto the production ofproduce electricity.

The nuclear core design is based upon a new conversion technique in which an initial “starter”"starter" section of the core provides the [[neutrons]] required to convert fertile material (used nuclear fuel, thorium, or [[depleted uranium]] (DU) into burnable [[fissile]] fuel.<ref>“With"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 webjournal |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.

|last=Parmentola

|first=J.

|title=Blue Ribbon Commission Webcast on America's Nuclear Future

|url=http://webcast.streamlogics.com/audience/index.asp?eventid=31330507

|accessdate=15 March 2010

|deadurl=yes

|archiveurl=https://web.archive.org/web/20110114102116/http://webcast.streamlogics.com:80/audience/index.asp?eventid=31330507

|archivedate=14 January 2011

|df=

}}</ref> The starter U235 is consumed as the used nuclear fuel/DU or used nuclear fuel/thorium is converted to fissile fuel. The core life expectancy is approximately 30 years (using used nuclear fuel and DU) without refueling.

Substantial amounts of valuableusable fissile material remain in the EM2 core at the end of life. This material iscan be reused as the starter for athe second generation of EM2s, without conventional [[nuclear reprocessing]].<ref>{{Citationcite neededweb|url=http://www.ga.com/advanced-reactors |title=Advanced Reactors |publisher=General Atomics |access-date =February 2016Feb 19, 2018}}</ref> There is no separation of individual heavy metals required and no additional [[enriched uranium]] needed. Only unusable [[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 storedTechnology 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.

==Economics and workforce capacity==

TheEM2 expectedpower costcosts advantagesare ofexpected EM2to liebe inlower itsdue simplifiedto high power conversion system(from thermal input to electric output) efficiency, whicha operatesreduced atnumber highof temperaturescomponents, yieldingand approximatelylong 50core percentlife. greaterEM2 is expected to achieve a [[thermal efficiency]] of above 50% due to its high core outlet temperature and aclosed correspondingBrayton one-thirdpower reductioncycle. inThe materialsBrayton requirementscycle thaneliminates thatmany expensive components, including [[steam generator]]s, pressurizers, [[Condenser (heat transfer)|condenser]]s, and feedwater pumps. The design would utilize only 1/6th of currentthe nuclear reactorsconcrete of a conventional light water reactor.<ref>{{cite news|url=httphttps://onlinewww.wsj.com/articlearticles/SB10001424052748703791504575079370538466574.html | title=General Atomics Proposes a Plant That Runs on Nuclear Waste|last=Smith|first=Rebecca|date=Feb 22, 2010|work=[[The Wall Street Journal]]}}</ref>

Each module can be manufactured in either U.S. domestic or foreign facilities using replacement parts manufacturing and supply chain management with large components shipped by commercial truck or rail to a site for final assembly, where it will be fully enclosed in an underground containment structure. Dry cooling capability allows siting in locations without a source of cooling water.

If the reactor is to become part of a [[hydrogen economy]], the coolant outlet temperature of 850&nbsp;°C would allow the [[sulfur iodine cycle]] to be used which directly converts thermal energy into hydrogen (without electric or other intermediate steps) with an overall thermal efficiency around 50%.

==Nuclear waste==

The EM2 utilizescan burn used [[nuclear fuel]], also referred to as “"[[spent fuel]]”" from current reactors, which are [[light water reactors]]. It can taputilize an estimated 97% of unused fuel that current reactors leave behind as waste.

Spent fuel rods from conventional nuclear reactors are put into storage and considered to be [[nuclear waste]], by the nuclear industry and the general public.<ref>{{cite news|url=httphttps://articleswww.latimes.com/2010archives/la-xpm-2010-mar/-11/opinion/-la-le-thursday11-2010mar11/-story.html|title=Letter to the Editor in Response to "Nuclear power – not a green option – it generates radioactive waste; it requires uranium that's dangerous to mine; it's hugely expensive,"|last=Parmentola|first=John|date=March 11, 2010|work=[[Los Angeles Times]]}}</ref> Nuclear waste from light water reactors retains more than 9995% of its original energy; thebecause such reactors cannot burn fertile U238, while fast reactors can. The current U.S. inventory of spent fuel is equivalent to nine trillion barrels of oil - four times more than the known reserves. EM2 uses this nuclear waste to produce energy.

==Non-proliferation==

By using spent nuclear waste and depleted uranium stockpiles as its fuel source, a large-scale deployment of the EM2 is expected tocould reduce the long-term need for uranium enrichment and eliminate conventional nuclear reprocessing, which requires plutonium separation.<ref>{{cite news|url=httphttps://spectrum.ieee.org/energy/nuclear/downsizing-nuclear-power-plants/|title=7. "Downsizing Nuclear Power Plants – Modular designs rely on ‘economies'economies of multiples’multiples' to make small reactors pay off big," |last=Fairley |first=Peter |date=May 11, 2010 |work=[[IEEE Spectrum]]}}</ref>

Conventional light water reactors require refueling every 18 months. EM2’sEM2's 30-year fuel cycle minimizes the need for fuelingfuel handling and canreduces reduceaccess theto proliferationfuel concernsmaterial, associatedthus withreducing refuelingproliferation concerns.

==EnergyNuclear safety and security==

EM2 utilizes passivelypassive safety systems designed to safely shutdown the reactor in emergency conditions using only gravity and natural convection in emergency conditions.<ref>{{cite web|url=http://www.andrewga.cmu.educom/user/ayabdull/Prasad_SMRDesc.pdfadvanced-reactors |title=Advanced Reactors |publisher=General Atomics |access-date = Feb 19, 2018}}</ref> Control rods and drums 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 a safety-enhanced fuel cladding in the core ensures no hydrogen production during accident scenarios and allows an extended period of response when compared to the use of Zircaloy metal cladding used in current reactors, which are reactive and not as heat resistant as ceramics in EM2.

Underground siting in a silo improves safety and security of the plant toagainst terrorism and other threats.

The EM2’sEM2's high [[operating temperature]] can provide process heat for [[petrochemical]] fuel products and [[alternative fuels]], such as [[biofuels]] and [[hydrogen]].<ref>{{Cite web | title = Small Nuclear Power Reactors | url=http://www.world-nuclear.org/info/inf33.html | publisher=World Nuclear Association | date = August 2010 | access-date=2010-09-09 | archive-date=2013-02-12 | archive-url=https://web.archive.org/web/20130212224137/http://www.world-nuclear.org/info/inf33.html | url-status=dead }}</ref>

==A Realistic Assessment of the EM2==

{{OriginalResearch|section|date=March 2017}}

{{Essay-like|section|date=March 2017}}

The EM2 is just another re-incarnation of the helium-cooled fast neutron spectrum reactor, referred to as the Gas-Cooled Fast Reactor (GCFR). This type of reactor has some attractive characteristics, but safety is not one of them. To achieve its objectives of high nuclear fuel utilization with relatively compact size, the reactor must operate with very high power density and with very little material in the reactor core that can absorb heat during a severe accident. As a result, this type of reactor will undergo a very rapid meltdown during severe accidents with loss of coolant and system depressurization, and represents a substantially less safe alternative to modern commercial reactors that use water cooling. Every major nuclear country has rejected this type of reactor concept, in part because of its relatively poor safety characteristics.

The EM2 introduces additional safety and practical engineering challenges beyond the conventional GCFR. The EM2 fuel is an unproven concept and is expected to vent (release) its radioactive fission products while the reactor is operating, which essentially eliminates the fuel as a barrier to radioactivity release and defeats the concept of defense-in-depth to radioactivity release required by the U.S. Nuclear Regulatory Commission. The EM2 proponents also claim the reactor core can last up to 30 years without requiring refueling. Proving a new nuclear fuel can last this long without significant levels of failure is practically impossible, especially from a nuclear regulatory licensing perspective. Furthermore, this type of fuel cycle can represent a significant risk for proliferation of nuclear fissile material. The EM2 core is fueled with large quantities of depleted uranium which converts to weapons-grade plutonium long before the end of its claimed 30 year fuel cycle. In fact, according to a study performed by Princeton University <ref>[http://www.ans.org/pubs/journals/nt/a_19873] Glaser et al., Nuclear Technology, Vol. 184, October 2012, pp 121-129)</ref>, an EM2-type reactor sized to produce 200 MWe will produce about 750 kg of super-grade plutonium (> 95% of the fissile isotope Pu-239) within about 5 years{{dubious|date=March 2017}}, which is enough plutonium for about 70 nuclear weapons. Conventional light water reactors (LWRs)are much more resistant to proliferation, with the plutonium in spent fuel containing about 60% Pu-239 after about the normal 3 to 4 years of irradiation. In terms of safety and proliferation risks, the EM2 is an unacceptable nuclear reactor concept, especially for commercial deployment in a post-Fukushima world and increased concerns over nuclear proliferation.

==See also==

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==References==

{{Reflist}}

<small>10. Wald, Matthew L.(Sept. 24, 2013). [https://www.nytimes.com/2013/09/25/business/energy-environment/atomic-goal-800-years-of-power-from-waste.html?_r=0 Atomic Goal: 800 Years of Power From Waste]". ''New York Times.'' Retrieved 10 December 2013.

11. Lee, Morgan. (Aug. 18, 2013). [http://www.utsandiego.com/news/2013/aug/18/reactor-redefined-general-atomics/all/?print Smaller, transportable nuclear reactor]. ''UT San Diego''. Retrieved 5 November 2013.

12. King, Llewellyn. (Aug. 21, 2013). [http://www.csmonitor.com/Environment/Energy-Voices/2013/0821/For-nuclear-good-things-come-in-small-packages For nuclear, good things come in small packages]. ''Christian Science Monitor.'' Retrieved 10 December 2013.

13. The Engineer (Sept. 11, 2013). [http://www.theengineer.co.uk/video/general-atomics-presents-small-modular-reactor/1017096.article General Atomics presents small modular reactor].''The Engineer.'' Retrieved 10 December 2013.

14. Haggerty, Dan (Sept. 12, 2013). [http://media.ga.com/video-library/em-on-evening-news-as-holding-the-key-to-changing-the-future-energy-supply/ Holding the key to changing the future energy supply]. ABC-KGTV 10. Retrieved Sept. 13, 2013.

15. Hood, David (Sept. 5, 2013). [http://www.ocregister.com/articles/reactor-524508-energy-nuclear.html%20Rohrabacher%20pitches%20scaled-down%20nuclear%20power%5D Rohrabacher pitches scaled-down nuclear power]. ''Orange County Register.'' Retrieved 15 September 2013.

16. Bullis, Kevin (Aug. 19, 2013). [http://www.technologyreview.com/news/518116/a-nuclear-reactor-competitive-with-natural-gas/ A Nuclear Reactor Competitive with Natural Gas]. ''MIT Technology Review.'' Retrieved 10 December 2013.

17. St. John, Alison (May 21, 2012). [http://www.kpbs.org/news/2012/may/21/better-nuclear-power-plant/ A better nuclear power plant?] KPBS News. Retrieved 12 September 2012.

</small>

== External links ==

* {{official website|http://www.ga.com/nuclearadvanced-energy/energy-multiplier-modulereactors}}

* 2011-11-28: [https://web.archive.org/web/20130530133706/http://www.nuc.berkeley.edu/Colloquiums/2011-11-28 Presentation about the EM2 reactor at the Department of Nuclear Engineering, University of California-Berkeley], [https://web.archive.org/web/20150714102414/http://www.ustream.tv/recorded/18810437 ustream video] [https://web.archive.org/web/20130530143549/http://www.nuc.berkeley.edu/Colloquiums/2010-5-3 Previous presentation]

* 2015-05: [[Testimony]] of the Sr. Vice President of [[General Atomics]] before the [[Committee on Science, Space and Technology]]: [http://docs.house.gov/meetings/SY/SY20/20150513/103447/HHRG-114-SY20-Wstate-ParmentolaJ-20150513.pdf]