Improvements to conditions for workers on the Fukushima Daiichi site feature alongside details of plans for management of contaminated water and for the removal of fuel from unit 4's used fuel pool in Tepco's latest report on progress at the site.
|NFT-22B storage containers will be used to transfer used fuel to Fukushima Daiichi's shared pool (Image: Tepco)
Measures to improve the working environment range from increases to wages for employees and the premium paid to contractors, to improvements to on-site facilities including break rooms, catering, cell phone communications and transportation. New management controls including improved operation procedures and clarification of command chains are being put in place to ensure enhanced safety and quality. Infrastructure improvements include the replacement and upgrading of equipment and structures put in place in the immediate aftermath of the 2011 earthquake and tsunami with more permanent or sturdier structures.
Tepco president Naomi Hirose identified on-site working conditions and safety as well as morale and motivation as some of the company's highest priorites. "We believe this is a very important element in regaining public trust," he said.
The report also details the steps being taken to manage accumulated ground and rainwater, including countermeasures to ensure that rainwater does not overflow from dykes designed to hold it. Like the water that is used to cool the reactors and used fuel, contaminated rainwater and groundwater must be contained and treated. Strategies to minimise the amounts of contaminated rain and groundwater as well as efforts to improve the integrity and capacity of storage tanks and to control rainwater inflows are already under way.
Some 370,000 tonnes of water are currently stored at the site. Installation of further storage tanks will increase storage capacity from the current 410,000 tonnes to some 800,000 tonnes by the end of fiscal 2015, with flange-type tanks - which have proved susceptible to leaks - to be replaced by more reliable welded tanks. Work is also being undertaken to improve facilities for the decontamination of stored water. Tepco says that it expects to see the measures currently being implemented lead to significant reductions in the level of radioactivity of the majority of stored water on site by March 2015.
Fuel on the move
Finally, the report provides a summary of preparations being made in order to transfer fuel from unit 4's used fuel storage pool to casks, ready for transfer to the site's shared used fuel storage pool which was undamaged by the events of March 2011. Removal of the fuel from unit 4's pool has been identified as one of the highest decommissioning priorities at the site. Unit 4 was off line for maintenance when the earthquake and tsunami struck, and its full core load of fuel, plus used fuel from previous operation, was being stored in a fuel pool at the top of the reactor building.
A cover has been built over the reactor building, which was badly damaged by an explosion of hydrogen from unit 3, and specially designed fuel removal facilities including a fuel-handling machine and crane, are being installed in preparation for the fuel removal. The fuel will be removed and transferred to transportation casks under water. The equipment has been designed to withstand an earthquake of magnitude 9.0, Tepco says.
The removal of the fuel is expected to begin in mid-November.
Researched and written
by World Nuclear News