6 Dec (NucNet): Tokyo Electric Power Company (Tepco) has made significant progress towards decommissioning the Fukushima-Daiichi nuclear plant, but should consider a controlled release of radioactive water into the sea in an effort to manage contaminated water, says a preliminary report by the International Atomic Energy Agency (IAEA).
The report, prepared by a team of experts that has been visiting the stricken plant, says a sustainable solution must be found to the problem of managing contaminated water, “including the possible resumption of controlled discharges to the sea”.
The report says finding a solution to the problem of contaminated water would require considering all options, including the possible resumption of controlled discharges to the sea.
“Tepco is advised to perform an assessment of the potential radiological impact to the population and the environment arising from the release of tritium and any other residual radionuclides to the sea in order to evaluate the radiological significance and to have a good scientific basis for taking decisions,” the report says.
The IAEA team said the continued operations for removal of caesium from accumulated contaminated water were “very efficient”. The report noted a number of countermeasures for the protection of the marine environment, including the isolation and removal of contamination sources and prevention of leakages.
Other issues identified as “very challenging” by the expert team were the removal of nuclear fuel and the removal of debris.
The IAEA team said the revised roadmap for the decommissioning of Fukushima has been developed “based on more-realistic assumptions” and a “more proactive organisational structure has been adopted” to deal with the most important issues.
The IAEA experts said they recognised “substantial efforts” made by Tepco in transforming of the Unit 4 operating floor so fuel assemblies could be removed from the spent fuel pool. However, they said Tepco should consider “alternative options” to support fuel storage operations in the newly constructed common spent fuel pool and future fuel disposal facilities.
The report says that Tepco should continue to evaluate and optimise the plan for installing a “freeze wall”, active sub-drain and water recharge in an effort to reduce the seeping of groundwater into the reactor and turbine buildings.
The team said Tepco has become more proactive in the implementation of a public information and communication campaign through the establishment of a social communications office and defining criteria for methods and timing of public information releases.
In August 2013, Tepco came under strong criticism for its attitude towards disclosing information.
The full IAEA report will be made available in February 2014.
The preliminary summary report is online: www.iaea.org/newscenter/focus/fukushima/missionreport041213.pdf
