Satellite image of tsunami-damaged Fukushima Daiichi nuclear power plant. Credit: Digital Globe; Wikipedia.

Last week the UN International Atomic Energy Agency released a preliminary report from its fact finding mission to Japan to identify and share early lessons learned from the Fukushima Daiichi accident. A full report will be provided to the IAEA Ministerial Conference on Nuclear Safety to be held in Vienna, June 20-24.

The preliminary report condensed the findings into eleven points that can be categorized generally as external hazards, severe accident management and emergency preparedness. Several of the points commend the Japanese government and TEPCO officials for their openness with IAEA experts, the dedication of the government to protecting the public and the onsite response of staff under arduous circumstances as the disaster unfolded.

Other important points are (paraphrasing):

  • The roadmap for recovery of the affected reactors is important and will need modification as new information becomes available, perhaps with assistance from the international community.
  • The tsunami hazard was underestimated. Nuclear designers and operators should protect against all natural hazard risks and periodically reassess to accommodate new information and experiences.
  • Design protections for extreme external events should include depth, physical separation, diversity and redundancy, especially events with “common mode implications such as extreme floods.”
  • Nuclear regulatory systems should include extreme external events in their periodic reviews and ensure that regulations and roles are aligned with IAEA safety standards.
  • Nuclear design and operations, including emergency response, should account for the possibility of combinations of severe external events.
  • Risks associated with hydrogen need to be evaluated, with provision made for mitigation systems.

The preliminary report also points out that hardened onsite emergency response centers are necessary for housing resources, communications apparatus and equipment that controls essential plant functions. Simple, robust gear should be available to restore essential safety functions as quickly as possible.

Unofficially, fact-finding activities will continue indefinitely. Earlier this week, for example, the BBC reported that Japan’s nuclear safety agency will be reporting to the IAEA that it has doubled its estimate of how much radiation was released during the week after the accident and expanded the evacuation zone around the plant. The Nikkei/Dow Jones news agency reports that Japan also will tell the agency that it will give more independence to the nation’s nuclear regulators, and will “separate the Nuclear and Industrial Safety Agency from the Ministry of Economy, Trade and Industry, which is also charged with promoting the use of nuclear power.”