Japanese electrical utility TEPCO has clarified its intentions about the pumping out of high-level contaminated water from its damaged Fukushima Daiichi unit 2 and 3 turbine building basements to two radwaste treatment buildings on site.

It has decided to pump out more water than originally planned to help prevent leaks in the week before a water treatment system becomes available (expected to be around 15 June).

In April and May, it pumped 9500 tons of contaminated water from the unit 2 turbine building to the Main Process Building of the Centralized Radiation Waste Treatment Facility. It also pumped 3700 tons of water from the Unit 3 turbine building to the Miscellaneous Solid Waste Volume Reduction Treatment Building of the Centralized Radiation Waste Treatment Facility.

TEPCO stopped water transfer in late May for two reasons: because capacity was running low, and to check water levels. At that time, a leak was discovered in the latter Miscellaneous Solid Waste Volume Reduction Treatment Building; the water was declining. Water was found in an adjacent underground corridor. It has stated that it expects the leak to stop when water levels are equalised, although it has not specified which levels, or how that might happen.

At the same time, the water levels of the unit 2 and unit 3 turbine hall basements are continuing to rise because of reactor water injection, risking the possibility of more leaks.

To solve the problem, TEPCO has decided to pump out more water from the turbine halls into the Main Process Building of the Centralized Radiation Waste Treatment Facility (which was not leaking). It will transfer an extra 4000 tons, but will aim to keep the water level below the level of underground water at low tide. It restarted pumping in early June and as of 9 June had pumped out 2500 extra tons of water.

In the meantime, water continues to be pumped out of the unit 6 turbine hall basement into temporary storage tanks. A total of 9250 tons had been transferred as of 7 June.

In other news, work has begun to set up a system to filter air inside the unit 2 reactor building, as it did at unit 1. Investigations in early June found relatively high levels of radiation (approx 1.6×10^-1 Bq/cm3, 100 times regulatory limits.

Also, work to install steel pillars to shore up the unit 4 spent fuel pool has begun. Although an analysis has shown that the damaged exterior walls would still withstand a design basis earthquake, TEPCO has decided to add in an extra margin of safety.

Finally, Japan Atomic Industrial Forum has published a summary of the status of TEPCO’s efforts to meet its goals declared in its restoration plan for Fukushima Daiichi through the end of June. This summary, which shows that there is still much to be done, replaces its previous reactor-by-reactor status summary published since 14 March, three days after the devastating earthquake and tsunami.

FilesReactor-by-reactor Fukushima Daiichi restoration progress summary as of 14 June, from JAIF
Fukushima Daiichi parameters as of 13 June by JANTI