All Things Nuclear -- Sunday Update on Fukushima Reactors

[FourScore]

All Things Nuclear
Insights on Science and Security
March 13, 2011 • 0 Comments
Sunday Update on Fukushima Reactors
| by Ed Lyman | nuclear power | nuclear power safety | Japan nuclear |

As of 7 pm EDT Sunday 3/13/11

We reported earlier about the situation at Fukushima Dai-Ichi reactor Unit 1. The nuclear crisis in Japan took a turn for the worse as serious problems developed in reactor Unit 3.

Officials from Tokyo Electric reported that after multiple cooling system failures, the water level in the Unit 3 reactor vessel dropped 3 meters (nearly 10 feet), uncovering approximately 90 percent of the fuel in the reactor core. Authorities were able to inject cooling water with a fire pump after reducing the containment pressure by a controlled venting of radioactive gas. As they did with Unit 1, they began pumping sea water into Unit 3, which is highly corrosive and may preclude any future use of the reactor even if a crisis is averted.

However, Tokyo Electric has reported that the water level in the Unit 3 reactor still remains more than 2 meters (6 feet) below the top of the fuel, exposing about half the fuel to air, and they believe that water may be leaking from the reactor vessel. When the fuel is exposed to air it eventually overheats and suffers damage. It is likely that the fuel has experienced significant damage at this point, and the authorities have said they are proceeding on this assumption.

One particular concern with Unit 3 is the presence of mixed-oxide (MOX) fuel in the core. MOX is a mixture of plutonium and uranium oxides. In September 2010, 32 fuel assemblies containing MOX fuel were loaded into this reactor. This is about 6% of the core.

I have done considerable analysis on the safety risks associated with using MOX fuel in light-water reactors. The use of MOX generally increases the consequences of severe accidents in which large amounts of radioactive gas and aerosol are released compared to the same accident in a reactor using non-MOX fuel, because MOX fuel contains greater amounts of plutonium and other actinides, such as americium and curium, which have high radio-toxicities...

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[WheelWalker]

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Blessings.

[SidDithers]

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Sid

[PufPuf23]

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[northoftheborder]

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[Wilms]

4. Thanks. n/t