Associated Press today is repeating unconfirmed reports that:

Japan has decided to raise the severity level of the crisis at its tsunami-stricken nuclear power plant to 7 — the highest level and equal to the 1986 disaster at Chernobyl in the former Soviet Union.

The INES rating is the international scale of safety incidents relating to nuclear and radiological events, which goes from 1 – being a breach of the rules – up to a 7, a major accident. So far the only level 7 event has been Chernobyl, designated an accident with “Widespread health and environmental effects. External release of a significant fraction of reactor core inventory.”

The Fukushima accident raises some interesting questions about INES*. The current rating of Fukushima at Level 5 is clearly not satisfactory, because Level 5 on the scale refers to:

Limited release of radioactive material likely to require implementation of some planned countermeasures.

• Several deaths from radiation.

• Severe damage to reactor core.

• Release of large quantities of radioactive material within an installation with a high probability of significant public exposure. This could arise from a major criticality accident or fire.

The reason why it could be argued that Fukushima does not rate as a 5 on INES is that there have been no deaths from radiation so far. Three workers died as a result of the earthquake and tsunami, but while a few workers have been hospitalised as a precaution, nobody has died from radiation poisoning at Fukushima.

Using this reasoning, Fukushima should not even rate as Level 4 on INES, because this is supposed to include “At least one death from radiation”.

Strangely, Level 7 on INES does not require any deaths to be reported from radiation, which arguably makes it more applicable to Fukushima than Level 5 and even Level 4. Fukushima is clearly a very serious accident that should rate very highly compared to other accidents. But should it really be Level 7, which is:

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

Clearly, the Fukushima accident has required major countermeasures that will require a lot of environmental work, but can anyone anywhere point to widespread health effects?

While a handful of workers have been hospitalised, nobody has yet been able to point to a single health problem, let alone widespread health problems.

To me, it looks plainly like Level 6:

Significant release of radioactive material likely to require implementation of planned countermeasures.

is the only applicable level, and I would not be surprised if this is the level Fukushima settles at. However, the fact that levels below it require deaths from radiation is a very significant anomaly. How is that fatal accidents can rate lower than Fukushima?

 All of which suggests that some nuclear wonks may need to sit down and have another look at INES.

 UPDATE: Claims the level has now been officially raised to 7.

UPDATE: It’s official, and I don’t agree with it. If the release of radiation is the determinant, why don’t they include that as criterion on their pyramids?

 *INES stands for International Nuclear and Radiological Event Scale, so calling it the INES scale, is like referring to the HIV virus or a PIN number.