Update from Dr. Saji- former Secretariat of Japan's Nuclear Safety Commission
Last Update: 17 April 2011
Links to Dr. Saji's Updates:Earthquake (58) Sunday, 08 May 2011.
I am sending this urgent appeal as a special issue of my series of Earthquake (1-21).
I would like to appeal to the international scientific community for organizing teams to develop;
1. Land contamination density maps showing a distribution of released radioactive species, in particular Cs-137.
2. Sea water contamination density maps showing a distribution of released radioactive species, in particular Sr-89 and Sr-90.
I am calling for these urgent actions based on the following reasons:
1. The Tohoku Earthquake (M9.0, 2011) and the subsequent gigantic tsunami, which arrived approximately one hour later, induced a loss of ultimate heat sink combined with a station blackout situation in all nuclear reactors of Fukushima Daiichi Nuclear Power Station. This initiating event is an unprecedented severe accident situation, followed with very complicated accident sequences, further complicated through different design characteristics and some variation in operational procedures during their accident management. By going through complicated sequences, a series of hydrogen explosions were triggered, resulting in releasing a significant amount of radioactive species into the atmosphere and into the ocean.
2. Unfortunately, due to the station blackout situation, the radiation monitoring data, such as a stack monitoring records, corresponding to the most critical time of releases, are absent. There is no robust data indispensable for assessment of, for example, the amount of radioactive species released to the environment, the time sequence of releases after the station blackout and route of the environmental releases.
3. Under this situation, it is anticipated that theoretical reconstruction of the environmental releases based on the distribution maps should be the only practical way.
4. With time, sampling will become harder, due to decay, atmospheric dispersion as well as oceanic dispersion. Thus an urgent action is called for.
5. TEPCO is a private company and they are not prepared to provide those data for scientific assessment of environmental impacts. Also, the Japanese government is currently too much occupied in bring the damaged plants under control as well as to provide necessary assistances to refugees.
The sampling of sea water is anticipated to be much difficult due to mobility of tide current and later storage of samples. It is urgent to find a method like ion exchange resin sampling, which works in the sea water environment under competition of reactions with Ca and Mg ions. As soon as the dissolved radio-nuclides are absorbed into the ion exchange resin, the remaining sea water can be duped back into the sea. Fortunately, Dr. Boris Burakov of Radium Institute informed me that Dr. Sergey Britvin from St. Petersburg University (Crystallography Department) recently developed (with his colleagues from Germany and Russia) really unique sorbent for radionuclide absorption. It is the layered hydrazinium titanate (LHT-9) compound of general formula (N2H5)1/2Ti1.87O4xH2O containing 6-7 wt. % of hydrazine chemically incorporated into TiO2-based matrix. This material has been tested by using real radio-nuclides. It is proven effective simultaneously for different radio-nuclides in a broad range of pH better than any zeolites. An additional advantage of this material is that after radionuclide absorption it can be converted by sintering in air into stable ceramic waste form (the titanate mineral composition is very similar to SYNROC). In my understanding, they are urgently investigation the effect of competition reactions.
Let me attach an accidental source term, calculated by scaling of the activation data included in UNSCEAR 2000: Report to the General Assembly, with Scientific Annexes, Volume II: Effects, Annex J, Exposure and effects of the Chernobyl accident, Table 1, Radionuclide Inventory in Unit 4 reactor core at time of the accident on 25 April 1986. In particular, I used the calculation by Sich, A.R., A.A. Borovoi and N.C. Rasmussen. The Chernobyl accident revisited: source term analysis and reconstruction of events during the active phase. MITNE-306 (1994).
Each time new sampling data became available from TEPCO as well as from surrounding measurements, I checked the sampling data with this table, to make sure that the important species are not missing. Almost all data from TEPCO does not include beta-emitting species.
Hoping to see reliable scientific bases for welfare of mankind,
P.S. For funding support, please consider to apply for the NSF (National Science Foundation) Rapid Response Research (RAPID) mechanism, which is used to support activities having a severe urgency with regard to availability of, or access to, data, facilities or specialized equipment, including quick-response research on natural or anthropogenic disasters and similar unanticipated events.
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