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April 12, 2011

The Register UK sets the record straight on the hyped fear and the NISA tables on Fukushima radiation

1. The Register UK - The total non-story of the Fukushima nuclear powerplant "disaster" – which has seen and will see no deaths or measurable health consequences for anyone anywhere – has received a shot in the arm today with the news that Japanese authorities have upgraded the incident to a Level 7 on the nuclear accident scale.

Residual heating in the cores at reactors 1 to 3 has now decayed down to less than 0.37 per cent of normal output power. It is this heating which has previously driven emissions of core material from the cores, and which plant personnel struggled to control in the hours and days after the tsunami knocked out backup cooling power and backup-backup batteries were exhausted. During that time heating levels, though falling fast, were initially 20 times what they are now.



Most media have chosen to report Japanese government calculations indicating (three-page PDF/56.7 KB) that perhaps 10,000 terabecquerels per hour of iodine-131 may have been emitted from the Daiichi cores in the hours following the initial decision to vent them. This is assessed as around 10 per cent of the emission levels seen at Chernobyl.

That's largely meaningless, however. If all the iodine emitted in one hour had been sitting still at a single point (no) and that had been the only radio-isotope present (no again) you could have stood 100 metres from that point for three hours and suffered zero health consequences. Becquerels of a given isotope don't relate closely or directly to health consequences: we need to look at dose rates instead.

At times, close to reactor buildings on the Daiichi site, radiation dose rates as high as 1,000 millisievert/hour have been recorded by remote instruments. That is serious radiation: after an hour exposed to it you'd be likely to suffer actual radiation sickness, though you'd be just about certain to recover. Two hours, and you might die: four hours, a fatal result would become likely. If millions of people were exposed to such levels for say a quarter of an hour, decades later you'd be able to point to increased cancer rates among them (though the risk to any individual would be negligible).

But these were in fact very brief spikes right next to a damaged core, resulting mostly from very short-lived isotopes that were decaying before they could drift beyond the plant fence. Nobody at all has been exposed to such levels

Thus far the worst exposure was suffered by three workers who stood in ankle-deep radioactive water for several hours and sustained doses above 100 millisievert from doing so, indicating local levels of 20-odd millisievert/hour. They have suffered zero health consequences as a result. As of the latest reports, as many as four other workers (of all the many hundreds present at the site) have gone above 100 millisievert: the maximum level allowed is 250 before being withdrawn from the operation altogether, but as is common in the nuclear industry intense caution is being exercised.

Danger beyond the plant fence has remained effectively nil. As of yesterday, according to nuclear experts at MIT in the States (reviewing data from Japanese and international monitoring teams on the ground) the highest dose rates seen within 30km of the plant have been 0.0016 millisievert/hour.

For context, you could live permanently under radiation levels of 0.0016 mS/hr and you would never achieve even half the annual dose levels permitted by airline crew.

The only actual health menace of any kind beyond the plant fence from Fukushima (and indeed following Chernobyl) has been presented by ingestion of radioisotopes in food: specifically of radioisotopic iodine. For adults this appears to have almost no effect, but in the case of children radio-iodine is taken up and concentrated in the thyroid gland very efficiently. Even though it decays away completely in a matter of weeks (iodine-131 has a half-life of just eight days), if a child ingests even quite small amounts of radio-iodine he or she will have a tiny extra risk of thyroid cancer in future – about 0.02 per cent, based on Chernobyl.

Fortunately, thyroid cancer – unusually among cancers – is almost always curable without ill effects (this is done, counterintuitively, using much larger amounts of iodine-131) and so the chance of such a child actually dying as a result of such exposure is unfeasibly tiny: less than one chance in a million.

In reality, the rise to Level 7 is a result of the constant badgering both from inside and outside Japan to the effect that the Japanese government is not taking this seriously. By calling it Level 7, the authorities are saying that yes, they assess the Daiichi situation as extremely serious. They really do care.

Fukushima has highlighted the impacts nuclear power can have under extreme conditions, but not in the way that uncle Froggatt says: environmental (nil impact), economic (slim to none impact – some 40-year-old plant written off a few years early, rolling blackouts mostly didn't occur and ended altogether yesterday) and societal (cretinous panic impact only).

If nuclear were allowed to be as dangerous as gas – that is, perhaps somewhere in the region of 400 times as dangerous in terms of deaths per terawatt-hour – there can be little doubt that electricity would become extremely cheap, maybe indeed too cheap to bother metering it for most users. Waste could be dealt with and supplies extended by many times by simply reprocessing fuel, something which the fearmongers have already managed to ban in many countries.

Cheap nuclear energy would hugely boost economic performance. It would also offer effectively unlimited fresh water supplies, and realistic options for space travel beyond low Earth orbit.

Some of us at least are getting a bit sick of the idea that you simply aren't allowed to tell frightened people quite bluntly to act their age – and we're getting more than just a bit sick of irrational or unscrupulous fairytale-spinners making them frightened in the first place
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2. NISA report on Fukushima radiation


Capacity factor blog has a comparison to Chernobyl releases

NOTE : Some estimate the radiation releases to be ten times lower than the NISA estimates and the radiation was mostly blown out over the Pacific Ocean



NUCLEOTIDE    HALFLIFE UNIT    PBQ %REL'D CHERNOBYL   FUKUSHIMA +1 WEEK +1 MO +3 MO +1 Y +3 Y
---------- ----------- ---- ------ ------      100% |      7.3% ------- ----- ----- ---- ----
Xe133              5.3 d     6,500    100     6,500 |     476.1  190.58  9.41  0.00 0.00 0.00
I131               8.5 d     3,200     55     1,760 |     130.0   73.46 11.26  0.08 0.00 0.00
Cs134            730.0 d       180     30        54 |       4.0    3.93  3.84  3.63 2.81 1.39
Cs137         10,950.0 d       280     30        84 |       6.1    6.10  6.09  6.07 5.96 5.69
Te132              3.3 d     2,700     40     1,080 |      79.1   17.77  0.13  0.00 0.00 0.00
Sr89              52.0 d     2,300      5       115 |       8.4    7.67  5.65  2.54 0.07 0.00
Sr90          10,220.0 d       200      5        10 |       0.7    0.73  0.73  0.73 0.71 0.68
Ba140             12.8 d     4,800      5       240 |      17.6   12.03  3.46  0.13 0.00 0.00
Zr95              65.0 d     5,600    3.5       196 |      14.4   13.32 10.42  5.50 0.31 0.00
Mo99               2.8 d     4,800    3.5       168 |      12.3    2.16  0.01  0.00 0.00 0.00
Ru103             39.6 d     4,800    3.5       168 |      12.3   10.89  7.28  2.55 0.02 0.00
Ce141             33.0 d     5,600    3.5       196 |      14.4   12.39  7.64  2.17 0.01 0.00
Ru106            365.0 d     2,100    3.5        74 |       5.4    5.31  5.09  4.54 2.72 0.67
Ce144            285.0 d     3,300    3.5       116 |       8.5    8.32  7.86  6.80 3.52 0.58
Np239              2.4 d    27,000    3.5       945 |      69.2    9.17  0.01  0.00 0.00 0.00
Pu238         31,390.0 d      1.00    3.5     0.035 |      0.00    0.00  0.00  0.00 0.00 0.00
Pu239      8,906,000.0 d      0.85    3.5     0.030 |      0.00    0.00  0.00  0.00 0.00 0.00
Pu240      2,401,700.0 d      1.20    3.5     0.042 |      0.00    0.00  0.00  0.00 0.00 0.00
Pu241          4,818.0 d       170    3.5     5.950 |      0.44    0.44  0.43  0.43 0.41 0.37
Cm242            163.0 d        26    3.5     0.910 |      0.07    0.06  0.06  0.05 0.01 0.00
---------- ----------- ---- ------ ------ --------- -                                        
                                     SUM;    11,712         859     374    79    35   17    9


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