In recent times we have had the first serious nuclear accident of the internet age, I am not sure why it is the internet age. The ‘ages’ were named after the materials used to make typical tools.
Stone age : Stone axes
Bronze age : Bronze swords made of a Cu / Sn alloy
Iron age : Iron ploughs
Then later the industrial age came, then we had the atomic age, the space age and then the internet age. My big problem is that for the majority of tools which we use in our lives we do not use atomic (nuclear), space or internet tools to do things like open cans of dog food or dig our gardens. For opening pet food cans and tending the vegetable patch I still use tools based on iron (steel).
While a nuclear powered digging machine or a space satellite which zaps the weeds might make life a little more easy (assuming you can afford to buy it) I think we will be sticking with steel spades and can openers for the forseeable future.
But I think that we do need to move onto something else. Recently a series of different reports have been published about the Fukushima event in Japan. Greenpeace have published a report as have the Japanese government and also Jon. M. Schwantes et. al. in the journal Environmental Science and Technology (DOI: 10.1021/es300556m) have published a paper in which they use the isotope signature of the accident to probe the event. In common with many things it is not always possible to make a direct measurement from samples which can be taken by hand, instead other measurements were used.
Now before we get going I will saw that it is impossible to have a single report which deals with a complex event in perfect detail. The problem is that if we examine one aspect of an event in great detail (using a state of the art study which includes as many details as possible) then this report is likely to become very large and close to impossible to read. If we then couple together a series of sections with a similar level of detail on all the different aspects of the event then we will end up with a wall of words which is impossible to comprehend.
Greenpeace have written about a recent Japanese report that
“The lethally high levels of radiation still present in the damaged reactors have prevented committee members from conducting a full analysis. They should be given all the time they need to complete their investigation.”
While the Japanese writers of the big government report stated that their mandate was
1. To investigate the direct and indirect causes of the Tokyo Electric Power Company Fukushima nuclear power plant accident that occurred on March 11, 2011 in conjunction with the Great East Japan Earthquake.
2. To investigate the direct and indirect causes of the damage sustained from the above accident.
3. To investigate and verify the emergency response to both the accident and the consequential damage; to verify the sequence of events and actions taken; to assess the effectiveness of the emergency response.
4. To investigate the history of decisions and approval processes regarding existing nuclear policies and other related matters.
5. To recommend measures to prevent nuclear accidents and any consequential damage based on the findings of the above investigations. The recommendations shall include assessments of essential nuclear policies and the structure of related administrative organizations.
6. To conduct the necessary administrative functions necessary for carrying out the above activities.
I have highlighted in bold the part which interests me most as a chemist, the Japanese panel also stated that they would not undertake a series of actions which included.
“investigations that would require on-site visits to reactors with dangerous levels of radioactivity.“
My understanding is that they have chosen quite wisely to avoid either waiting for a full examination of the reactor sites (which will take decades) or rushing into a dangerous area to gather data. My view is that samples collected from outside the reactor buildings, eye witnesses from the site, data from those sensors inside the plant which continued to work together with details which can be obtained from undamaged BWR plants. I see the problem of the clash of two cultures.
The scientific and engineering communities are seeking to get the best quality report which is correct, the speed of publication of the report is a secondary factor. In these communities it is better to delay the publication of a report if the delay will allow the quality to be improved. Also the answer has to be traceable, the computational methods used, the persons who did the work, the devices used and the samples used all have to be documented clearly in this type of work.
On the other hand the newspapers and many of the green NGOs (like Greenpeace) are aiming for speed of publication as their highest priority. In these reports the things which were used to produce the final answer are often not as traceable. What is interesting is when both the rapid publication of people like Greenpeace agrees with the slower and more thorough investigation which goes into the official reports. I would say that it is important to avoid being caught by statements by “The findings of both these reports match closely with the Lessons
from Fukushima report released by Greenpeace in February” in a trap where you think that both reports are the same.
The Greenpeace report has some similarities with and some differences from the Japanese government report, but I would say that neither report deals at length with the containment chemistry and the radiochemistry of the accident. I am unsure of what Greenpeace would be hoping for in an extended report which might be written in 20 years time when the insides of the containments have been fully explored. I think that a main part of the final purpose of the examination of the reactor buildings will be to determine what chemical and physical effects occurred during and after the accident.
The Greenpeace report is more dominated by photographs which relate loosely to the event, I am unsure why it is important in a report of 52 pages to include devote ten pages to photographs of things like wrecked buildings with very little explanation of what is going on in the photograph. For example on page 28 a whole page is devoted to a person holding a pair of radiation meters in a field. There are a series of important questions which are not answered in the text such as “what level of radioactivity has the person found in the field”, “what is the testing protocol” and “what is the date of the measurement”. I hold the view that the report should be written in a way to make these things clear rather than forcing the reader to dig deeply in a series of documents for the answers.
The Japanese government report is much more text and far fewer pictures in the main body of the text than the Greenpeace report, towards the end a lot of data is presented in appendix in the form of graphs. These graphs include things like the fraction of the public who were aware at a given time of some key events. While graphs might be less eye catching than photographs, I hold the view that a well labeled graph is a better way to communicate an idea to another person than a photograph which has little if any commentary in the caption.
The problem I see is that if I show 100 people a photograph with very little writing in the caption then a danger exists that each of the 100 people will interpret it in a different way, while in recent years there has been a backlash against science made by people like the postmodernists. Some people value their “feelings” above everything else and express the view that a series of different interpretations of the same evidence are equally valid, I have to disagree. Firstly there is no such thing as an impartial observer (Read the section of the Alan Chalmers book “Whats this thing called science” on induction for more details).
Secondly some interpretations of evidence are deeply wrong, for example if I was photographed by an alien (who has no knowledge of pet ownership) while walking my dog in the forest the aliens might think (based on the photograph) that I am some sort of cruel person who enslaves small white animals and chains them up. While this interpretation might fit the evidence in the photograph it is deeply flawed.
As a result I think that a report which is dominated by photographs which do not have a clear set of captions explaining what is going on is not a good report. But a report which uses the same amount of space for graphs and figures which bear captions which explain all the key points does communicate in a better way with the reader.
The comment that Greenpeace made of “The lethally high levels of radiation still present in the damaged reactors have prevented committee members from conducting a full analysis. They should be given all the time they need to complete their investigation.” suggests to me that Greenpeace want the Japanese government report to be a comprehensive report which deals with all aspects of the event. It might even be understood as Greenpeace suggesting that their report is more comprehensive.
I have read both reports and I can say that some rather important things are missing from both reports. Neither report mentions the transfer of cesium from soil to plants and then to humans via the food supply. I hold a view that this is an important issue, depending on the soil chemistry, the biology of the food production system and what countermeasures are taken the cesium in the diet is either going to be a small issue or a large issue. Also neither report gives a detailed list of the radionuclides released from the reactors and the amounts which were in the cores during the accident.
One of the best reports on this issue is the paper by J.M. Schwantes et. al., this paper uses the relative amounts of the different radionuclides in soil samples taken from Japan to work out what happened inside the cores of the damaged units.
This paper concludes
1. Volatility dictated by temperature and reduction potential dictated the fraction of the radioisotopes which were released.
2. All coolant was likely to have evaporated by the time the containments were vented.
3. The damage to the fuel was extensive.
4. The vast majority of the less volatile elements such as plutonium, niobium and strontium were contained within the reactors.
In the paper it has been calculated that the ratio of released cesium to plutonium from the Fukushima event was 100000 : 3 which suggests that the Fukushima event was far closer to a pure cesium / iodine release than the Chernobyl event was. The cesium to plutonium ratio for Chernboyl was about 10 : 1. I had from an early time made this prediction as the Chernobyl and Fukushima events were very different types of accident. One was a power surge while the other was overheating.
The most interesting thing in this paper is the graph of soil activity / reactor inventory against the oxygen potential of the dominate oxide form. This graph suggests that the more thermodynamically stable the oxide is then the less of the element will be emitted. The good news from this graph is that worst elements (plutonium) will not be emitted. The only problem is that the graph has some points which are a long way from the trend line.
More barium was released than this graph suggests while less ruthenium and silver was released than this simple model suggests. I think that I can explain why less ruthenium was released, the most easy ways to release ruthenium are either as fuel particles (which did not happen at Fukushima) or as ruthenium tetoxide which would not form as the reactors stayed under reducing conditions during the accident.