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Last login: Thursday, May 24, 2012
The EM2 is just another re-incarnation of the helium-cooled fast neutron spectrum reactor. While this type of reactor has some attractive characteristics, safety is not one of them. The reactor must operate with very high power density with very little material that can absorb heat during an accident. As a result, the reactor has the meltdown characteristics of a birthday candle on the surface of the sun, 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.
Until recently, General Atomics was the industry champion of the world's safest reactor concept, a modular, helium-cooled thermal neutron spectrum reactor, sometimes referred to as a Modular Helium Reactor (MHR). In contrast to the EM2, this reactor concept has a large quantity of material in the core that absorbs heat and prevents the reactor fuel from reaching meltdown temperatures, even if all of the coolant is permanently lost. Unfortunately, the senior management at General Atomics abandoned the MHR in favor of EM2, and has stuck with this strategy even in the aftermath of the Fukushima accident.
Japan has the high temperature engineering test reactor (HTTR), which is an operational, engineering-scale prototype of the MHR. It has been used to demonstrate the intrinsic safety characteristics of the MHR.Perhaps the events in Japan can lay the foundation for developing, demonstrating, and commercializing a next generation of nuclear power with intrinsic safety. International collaboration among the U.S., Japan, and other nations on the MHR would provide a relatively quick path for achieving this goal. More information on the HTTR is available at:
May 24, 2012 at 8:38 a.m.
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