Understanding Japan's Nuclear Disaster: INES Level 7

On April 12 the Kyodo news agency reported that the nuclear accident at the Fukushima nuclear plant had been assigned the maximum Level 7 security level. The new level had been given retroactively as a result of examining and reinterpreting what had already taken place. However, that is hardly reassuring in light of ongoing problems that are far from resolved. Also, for many, it raises the question of "What does Level 7 mean?"

Unfortunately, with the results that have already unfolded and continue to develop at various nuclear generators in Japan, we're all having to develop a new vocabulary and level of understanding when we discuss nuclear disasters and nuclear meltdowns. It's the latest incident where the world both observes and shares in a tragedy that defies most of our understanding. One consequence is we're all beginning to be comfortable with a new vocabulary to describe what appears to be an increasingly hostile world and climate.

Tsunamis, earthquakes, hurricanes and tornadoes are not the rare oddities in the news they once seemed. And images of each disaster have shrunk distances and made us feel close to those we've watched suffer terribly. The increase in our lexicon and ways to describe the seriousness of disasters has been necessary, since the first decade of this century seems to have introduced us to more of these disasters than in the whole of the last one.

We've witnessed enough earthquakes in the last couple of years that we've all become relative familiar with the Richter Scale to have, at least, a vague understanding of the significance of the numbers that come attached to each quake. Many of us on the East Coast know quite well the difference between a Category 1 storm versus a Category 3 or 4 one even if we didn't know the figures used are from something called the Saffir-Simpson Hurricane Scale.

Tsunamis seemed like a rather strange and foreign word that we were more afraid of pronouncing rather than something that was an actual threat a few years ago. Now the word skips trippingly from the tongue without a second's hesitation. Tsunami is both a word and concept that is now readily recognized around the world because of the calamitous events we've witnessed on several occasions in recent years. Before too long, I fully expect some on the West Coast to practice evacuation routines in the same way they have been and are rehearsed in Japan.

Many suspect that we might have had some role in bringing about some of the climate change the planet seems to be experiencing in the last decade in particular. However, there is little doubt that man is the clear author of some tragedies. When we conducted the first atom bomb test at White Sands Proving Ground on July 16, 1945, the Atomic Age began and, although we didn't know it at the time, we now needed a method of measuring the seriousness of a nuclear or radioactive event or accident.

Surprisingly, it wasn't until 1990 that the International Atomic Energy Agency (IAEA) introduced the International Nuclear and Radiological Event Scale (INES) to ensure that there would be a way of communicating information in case of nuclear accidents. The INES is another numeric scale where the concern and danger increases along with the larger number used to describe each event. The Richter Scale, for instance, has the lowest category of 1 referring to no damage up to an unheard of 10 – 9 being regarded as total destruction. The INES scale 1 refers to an anomaly and 7, the highest numeral, refers to the most serious event – a major accident. Nothing to worry about or everything as usual is represented by 0 in all of these scales. The INES, like many scales, lends itself well to graphics and the following chart or picture readily saves a couple of paragraphs:

I have omitted levels below Level 4 in the following paragraphs since, presently, they're of no consequence. Wikipedia describes the higher levels as follows:

Level 4: Accident with local consequences

Impact on People and the Environment Minor release of radioactive material unlikely to result in implementation of planned countermeasures other than local food controls. At least one death from radiation. Impact on Radiological Barriers and Control Fuel melt or damage to fuel resulting in more than 0.1% release of core inventory. Release of significant quantities of radioactive material within an installation with a high ­probability of significant public exposure. Level 5: Accident with wider consequences

Level 5: Accident with wider consequences

Impact on People and Environment Limited release of radioactive material likely to require implementation of some planned countermeasures. Several deaths from radiation.

Impact on Radiological Barriers and Control 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 example that most of us are most familiar with is the accident at Three Mile Island in March 1979.

Level 6: Serious accident

Impact on People and Environment Significant release of radioactive material likely to require implementation of planned countermeasures. The example given doesn't ring any bells but may be more familiar to others. It occured at Mayak in the USSR in 1957. Not surprisingly for the times, the impact on the local population is not fully known.

Level 7: Major accident

Impact on People and Environment Major release of radioactive material with widespread health and environmental effects requiring implementation of planned and extended countermeasures. The Chernobyl disaster in April 1986 is an example of this kind of major accident. The disaster resulted in dire consequences that created a Zone of Alienation, and the results are still very much in evidence today. Up until this point, there has only been one Level 7 event – The Chernobyl disaster. Far greater detail than has been provided in this brief article is available elsewhere. The most authorative and useful guide is probably the official INES: The International Nuclear and Radiological Event Scale User's Manual 2008 Edition. It is available in pdf format and is available in Russian and Spanish as well as English. Unfortunately, all of us will become a lot more familiar with the contents of the manual during the coming weeks, months and, even, years.

However, the system has not been used uniformly since the accident. As of March 23, it is a Level 5 according to the Japanese government. On March 15 the French Nuclear Agency had announced it a Level 6. Finnish nuclear authorities and the United States energy secretary all unofficially rate the accident as Level 6 on March 18. The inability of different experts to agree on the seriousness of the accident and the lack of accurate information, among other things, are increasingly worrying to some. (Many believe that the Level 5 is a conservative call since the situation is worse than Three Mile Island.)

Japan's second largest newspaper Asahi Shimbun, meaning Morning Sun, on March 25, suggested that the accident might well warrant a Level 6 rating, based on Japanese Nuclear Safety Commission numbers. (The paper has a circulation of just under 8 million for its morning edition and just over 3 million for its evening one.)

If we didn't know before, we now know that when some experts are describing the accident at the Fukushima Daiichi Nuclear power plant as a Level 6, we have reason for a lot of genuine concern.

On April 12 we learned that there had been a retroactive classification of the accident and that its level should in reality have been a Level 7, and thus far more serious than admitted previously. However, although it now regarded as a Level 7 incident, experts frequently reassure us that it is much less serious than Chernobyl since the nuclear waste has not been distributed over a large area as a result of an explosion.

This article's new introductory paragraph was written a little less than a month after we were being reassured that the danger was no more than that of a relatively harmless Level 5. Certainly the new classification will give rise to much debate as well as a great deal more concern over TEPCO's communications and handling of the disaster.