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Fukushima’s Unit 2 nuclear reactor’s meltdown was far worse than initially assumed

“.SimplyInfo.org Fukushima Daiichi Unit 2 Report 2015 (Excellent graphics) 

By The SimplyInfo Research Team
Dean Wilkie – Author
Edano San  – Author
Peter Melzer PhD – Author
Nancy Foust  – Editor

February 23, 2015

During the early events of the Fukushima Daiichi disaster unit 2 was given little attention in public facing information. It also appears that many of the outcomes from unit 2 may have been credited as being caused by other units a the plant or considered of unknown origin. Unit 2 may have been much worse in actuality than the public was being told and a larger contributor to the crisis. We reviewed multiple timelines and documentation sources of the events at Fukushima Daiichi and those specific to unit 2. This provided a clearer picture of what larger events may have been associated with unit 2′s event and the magnitude of the events inside unit 2. These events compared to the existing research into reactor failure modes and meltdown behaviors found that the events closely matched the expected outcomes………Unit 2′s meltdown and post meltdown progression was well anticipated by TEPCO based on their actions and their failure time estimates. TEPCO opened the torus vent line to the environment and left it open for 2.5 hours while fuel was likely already outside of the vessel and in the containment drywell, giving a clear route between corium and the environment. This action may have been unavoidable based on the available data from unit 2 in order to avoid a much larger containment failure that could not have been closed. It may have been the lesser of two bad options.

The available data and visual evidence for unit 2 show that contaminated water and fuel may have found a route out of the building through the basemat area. This highly radioactive water has shown up in the unit 2 turbine building basement and in the unit 2 trenches at the sea front, indicating the highly contaminated water may be flowing outside of the reactor building and in a manner quite different from the other two damaged units. If this is further confirmed to be the case, this may be a significant contributor to the ongoing highly radioactive water leaks that have defied efforts to block them.

Unit 2′s containment failure via the containment cap gasket continued to contribute a large percentage of the radiation escaping into the air at the plant even a year after the meltdowns. While the other two units have been admitted to have some failure or leakage from their reactor wells, unit 2 appears to be the major contributor to airborne releases via this route and continued to do so.

Newer information such as the failure of seawater injections to reach the RPV further ads to the growing body of information that indicates unit 2′s meltdown was far worse than initially assumed. Many early estimates of the extent of unit 2′s meltdowns were dependent on the assumption that water reached the melting fuel in quantities large enough to cool or cover the melted fuel. This newer understanding of the water injection shows those early estimates to be incorrect and that unit 2′s meltdown was much more severe than initially assumed. The timing of major events at the plant that tie to events at unit 2 and TEPCO’s increasing alarm over the degrading conditions of the plant indicates that unit 2 may have posed an even larger threat than the other two units at the plant. The chance event of the blow out panel dislodging early in the series of events may have helped unit 2 avoid a hydrogen explosion as seen at the other units. The actual meltdown and the extent of the damage at unit 2 may have been worse in many ways. http://www.fukuleaks.org/web/?p=14318

February 27, 2015 - Posted by Christina Macpherson | Fukushima 2015