Japan could be saddled with fragile and hazardous reactors at the Fukushima No. 1 nuclear power plant for years to come, warned an official with the Nuclear Regulation Authority.
Atsuhiko Kosaka said many challenges remain unresolved and must be dealt with before serious work can begin to scrap the reactors.
Kosaka heads the agency's Nuclear Regulation Office that is overseeing the early decommissioning efforts under way by plant operator Tokyo Electric Power Co.
Excerpts from an interview with The Asahi Shimbun follow:
Question: What are you paying most attention to regarding work at the site?
Kosaka: One thing is to prevent inspectors and workers from being exposed to radiation unnecessarily, and another is to prevent injuries.
Radiation levels have declined overall on the premises of the plant since the early stage of the disaster, but we are not totally aware of the distribution of radiation levels in areas where no work is under way and where rubble has yet to be cleared.
Lighting has yet to be restored inside buildings, so we have installed temporary lighting for construction work, but in other areas, we need to use flashlights to proceed with our work.
Q: Radiation levels remain high in many areas outside the reactor buildings. For example, they stand at 900 microsieverts per hour near a radioactive water purification plant. Do you have anything to say about that?
A: Radiation hot spots could be lurking anywhere, so it is indispensable to carry dosimeters when you go to areas where little information is available.
Both the situations on the ground and the conditions of radiation are constantly changing. For example, rubble on the top floor of the No. 4 reactor building used to shield radiation from the No. 3 reactor, but the rubble has been cleared and the shield is gone. Radiation levels are higher now.
Q: The decommissioning comes after an unprecedented triple meltdown. Do you have any preventive measures against possible problems?
A: TEPCO's work is like groping in the darkness and has involved an array of problems.
Last winter, for example, frozen pipes and pumps in the cyclic water injection system to cool down the reactors caused a number of water leaks.
Appropriate control methods need to be developed to deal with one situation on the ground to another, and the condition of one piece of equipment to another.
Q: What challenges remain for doing that?
A: There has certainly been some progress on the hardware front, such as relocating high-voltage switchboards to higher ground and preparing against a total loss of power supply.
Further improvement, however, would require strengthened command and control. We are currently in a "whack-a-mole" situation, with ad hoc responses used in every problem that arises.
I want TEPCO to learn lessons from the past two years and try to come up with measures to prevent problems.
(This article is based on an interview by senior staff writer Hisashi Hattori.)
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