A disastrous piece of risk communication?

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understandinguncertainty.org was produced by the Winton programme for the public understanding of risk based in the Statistical Laboratory in the University of Cambridge. The aim was to help improve the way that uncertainty and risk are discussed in society, and show how probability and statistics can be both useful and entertaining.

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Yesterday’s announcement that the Fukushima accident was now upgraded to a Level 7 was greeted with some consternation, since this is not only the same level as Chernobyl but as high as the scale can go – there is no Level 8. But is this scale really fit for its purpose?

The International Nuclear and Radiological Event Scale(INES) is intended to be "used for promptly and consistently communicating to the public the safety significance of events associated with sources of radiation". In the guidance manual, Level 7 is technically defined as

“Level 7: An event resulting in an environmental release corresponding to a quantity of radioactivity radiologically equivalent to a release to the atmosphere of more than several tens of thousands of terabecquerels of 131I.”

It therefore has a technical definition in terms of radiation release translated to an equivalent mount of radioactive iodine.

But the definition of Level 7 that is communicated to the public is in terms of the impact on people and the environment:

“Major release of radioactive material with widespread health and environmental effects requiring implementation of planned and extended countermeasures"

The guidance for using this scale says

  • Mention the actual confirmed consequences such as deterministic health effects to workers and/or members of the public;
  • —Provide an estimate of the number of workers and/or members of the public exposed as well as their actual exposure;
  • —Affirm clearly when there are no consequences to people and the environment;
  • —Mention any protective action taken.

However the April 12th press release of Japanese Ministry of Economy, Trade and Industry (METI) does not appear to follow this guidance. Instead it focuses solely on the technical definition, in reporting estimates of 370,000 and 630,000 terabecquerels (TBq) discharged (although pointing out that the corresponding figure for Chernobyl was 5,200,000 TBq). These figures reflect radiation at the start of the accident and were obtained by combining the different reactors together, whereas previously each was considered as a separate incident. No mention was made in the press release of the potential health impact, in spite of the explicit guidance on the use of INES.

So we have a scale, intended for popular use, whose technical definition has little relation to the phrase used in its media communication, and whose use has required repeated clarifications.

The top end of the scale also seems very limited and, with full acknowledgement to Nigel Tufnel, I would suggest it should be extended to 11.

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Spot on. As with many other risk rankings, INES is risk communication designed with too little input from risk communication experts. INES is the work of scientists and engineers and bureaucrats. The latest version, developed over the past several years by the IAEA in consultation with member states, is constrained from being too precise by international politics. And it's only a guide, to be used at the discretion of individual member states, so a 5 to one nation can be a 7 elsewhere. Further, the detailed guidance can be followed, or not. All of which is problematic. To say nothing of the inherent failure to recognize that such numeric rankings, appealing as they are, do not relate the risk with any acknowledgment of nor respect for the affective/instinctive/emotional nature of events that matter so much to the information recipients. David Ropeik dpr@dropeik.com

CNN http://tinyurl.com/3ecm3az illustrates the difficulties the scale and poor use of it can create.

This is a marginal comment, not about the INES but about risk assessment. Before Fukushima accident the risk of a nuclear plant had an accident was something like 10^-6. This magic number is use to justify building more and more nuclear plants world wide. I wondering what this 10^6 means! I understand that this 10^-6 is a sort of "operational risk", but Fukushima showed that the real threat was a "contextual risk". This contextual risk is composed for risk factors, which are external to the nuclear plant, however they strongly influence its operativity. Pablo Verde