Monday 26 August 2013


It was back in June. An acquaintance who lives in the Shima district of Koriyama was grumbling about the decontamination work at her house. First the boss man came, re-moved 5 cm of soil from the garden, took readings and having satisfied him-
self that radiation could be halved (that seems to be the criterion, not to reduce radiation to a certain level), he disappeared leaving sub-contractors to carry out the work. Shrubs and trees were pruned and the top layer of soil removed. Several houses in the vicinity were having work done at the same time so one moment there would be 8 workers in the garden, the next minute - just as she'd taken out some tea (!) - there were none. It took the best part of a week.

She and her husband were complaining that more time seemed to be spent recording and photographing each branch as it was cut, rather than actually doing the work. You have to take this with a grain of salt but you get the picture. At the end of the week they dug a hole about 2 metres by one metre and one metre deep behind the shed at the back of the garden and buried the plastic sacks of soil. Then they covered the garden with rough sand (yamazuna 山砂) which she was convinced was going to kill her plants. I met her a month later and she hadn't yet had the final results which were to come in the post. She's in her 70s and what with the heat she'd found the whole thing stressful. No doubt younger families would have welcomed having the work done.

The city of Koriyama, 60 kms from Fukushima Daiichi, was not evacuated and is not eligible for decontamination at central government expense. But early on the then Mayor decided to carry out its own decontamination plan to reassure residents and stop the outflow of people. Work started in the most heavily contaminated areas (around Ikenodai, Saikon) in October 2012 and is now being rolled out across the city.

I want to point you to an excellent piece of work by Azby Brown on this subject entitled. Decon or Con: How is Remediation being Managed and how effective is it? available on the Safecast website. It's a bit long but clearly written and easy to understand. Safecast, a global voluntary organisation, takes issue with the fact that there is no independent evaluation of decontaminaton (or 'remediation') and sets out to try and compare their readings with official before-and-after readings taken by the government. Accessing the government data seems to have been very time-consuming and Azby deserves credit for ferreting it out.

There are good maps and explanations of the different zones, explanations of how decontamination is to be managed, how the government's dose rate calculations are reached, and estimates of the effects of natural decay and weathering. To summarize, the goal was to reduce radiation in areas over 20mSv/year (the evacuated areas) rapidly to 20 mSv/year and to reduce radiation in other areas (Koriyama included) over the long term to 1 mSv/year. The evacuated areas are to be decontaminated at central government expense and other areas by the local authorities with subsidies etc. While work by local authorities seems to be progressing transparently (despite the grumbles of my friend above), work in the evacuated areas is behind schedule and proving more difficult. To quote, 'By early 2012, when pilot decontamination projects had been completed and the results examined, the government knew they could get areas with dose rates less than 30 mSv/yr down to below 20 mSv/yr, but not if they were originally 40 mSv or above ...'  So the outlook for residents in the exclusion zone is not good.

For those in the 'restricted residence zones' and 'preparing for return zones' things are more ambiguous. Safecast measured two sites to see if decontamination had been effective and to estimate whether it had accelerated natural reduction (weathering and radioactive decay). Results for the two sites were different which highlights the difficulty of this subject but it seems that decontamination is worth doing at higher levels but it's difficult to reduce further to 1 mSv/yr. This is polarising residents into those who say they will go back regardless and those who insist that levels need to be reduced to 1 mSv/yr.

Anyway, check it out here. A good read.
Safecast: Decontamination blog

The headline in yesterday's paper was Forest Levels Reduced by 38%. What this means is that airborne radiation had reduced by natural means (weathering and radioactive decay) in 2012 over the previous year by 38% in forests outside the exclusion zone, 10% of which was attributed to systematic felling of trees. (Seventy percent of Fukushima prefecture is forested.)

So it's a complex question that involves us all, not only those of us who live here but the nation's taxpayers who have to foot the bill. Questions are being raised about the cost-effectiveness of decontamination. Then there's the question of where to put all the soil. Not to mention the thorny question of compensation.
Thanks for reading this

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