19 Mars 2012
A Nuclear Safety Commission panel has decided on a draft to revise nuclear disaster management guidelines that would greatly expand the area in which priority protection measures would be take in the event of a severe accident.
The special committee on nuclear disasters endorsed the draft Friday, which would expand the priority protection zone to a radius of 30 kilometers for nuclear power plants, instead of the current eight to 10.
Based on the decision, the nuclear regulatory agency to be established in April or later will finalize the legal grounds for the guidelines and the criteria for evacuation under the revised guidelines, the officials said.
The new guidelines will be reflected in disaster management plans of the central and local governments, but many issues remain to be solved.
It is, therefore, uncertain whether such disaster management plans can be compiled in concrete and practical forms, along with moves to restart idle nuclear reactors.
The guideline revision was sought because the crisis at Tokyo Electric Power Co.'s Fukushima No. 1 nuclear power plant revealed many flaws in the current guidelines.
The special panel took into account, for the first time, the leakage of large quantities of radioactive material.
Some key points of the revised guidelines are as follows:
-- Areas within a 30-kilometer radius of nuclear plants will be designated as urgent protective action planning zones (UPZ), where disaster management measures such as evacuation plans are intensively undertaken as priorities.
-- Areas within a five-kilometer radius of plants will be designated as precautionary action zones (PAZ), where residents will be asked to immediately evacuate if a severe accident, such as a meltdown, occurs.
-- The establishment of plume protection planning areas (PPA), where prior distribution of iodine pills--to prevent damage to the thyroid gland--will be considered, in principle, within a 50-kilometer radius of plants.
-- The functions of accident response bases are to be separated into a command center--outside a 30-kilometer radius--and a "front-line control station."
To date, the guidelines have been in the government's Basic Disaster Management Plan only as items to be "respected sufficiently."
However, the government plans to clarify the legal weight of the guidelines under the Law on Special Measures Concerning Nuclear Emergency Preparedness.
In coordination with the new nuclear regulatory agency, local governments hosting nuclear power plants and surrounding municipalities will compile detailed evacuation plans and evacuation criteria.
Such evacuation standards should be decided based on actual accidents and measurements of radiation levels without relying on data from the System for Prediction of Environmental Emergency Dose Information (SPEEDI) of the science ministry, the officials explained.
The new guidelines will likely be reflected in local disaster management plans in steps, starting in late September. It will take a year or more to complete the revisions, the officials predicted.
However, it is quite difficult to compile concrete evacuation plans, and may be delayed if the launch of the new nuclear regulatory agency is postponed.
The guideline revisions will cover only nuclear power plants.