Dr Ian Fairlie
29th September 2014
When nuclear reactors are refueled, a 12-hour spike in radioactive emissions exposes local people to levels of radioactivity up to 500 times greater than during normal operation, writes Ian Fairlie. The spikes may explain infant leukemia increases near nuclear plants - but operators provide no warnings and take no measures to reduce exposures.
The story sparked much interest on social media sites, and perhaps more importantly, the article's scientific basis (published in the academic peer-reviewed scientific journal the Journal of Environmental Radioactivity) was downloaded over 500 times by scientists.
Given this level of interest and the fact that the UK government is still pressing ahead with its bizarre plans for more nuclear stations, we return to this matter - and examine in more detail an important aspect which has hitherto received little attention: massive spikes in radioactive emissions from nuclear reactors.
Refueling releases a huge radioactive emissions plume
Operating nuclear power plants (NPPs) contain large volumes of radioactive gases at high pressures and temperatures. When their reactors are depressurised and opened to refuel every 12-18 months, these gases escape creating a spiked emission and a large radioactive plume downwind of the station lasting for 12 hours or so.
However the emissions and plumes are invisible, and no advance warning is ever given of these spikes. The public is effectively kept in the dark about them, despite their possible health dangers.
For years, I had tried to obtain data on these spikes, but ever since the start of the nuclear era back in 1956, governments and nuclear power operators have been extremely loath to divulge this data.
Only annual emissions are made public and these effectively disguise the spikes. No data is ever given on daily or hourly emissions.
Is this important? Yes: these spikes could help answer a question which has puzzled the public and radiation protection agencies for decades - the reason for the large increases in childhood leukemias near NPPs all over the world.
Governments have insisted that these increased leukemias could not be caused by radioactive emissions from NPPs as their estimated radiation doses were ~1,000 times too low. But these don't take the time patterns of radioactive emissions into account, and so are riddled with uncertainties.
500 times more radiation released than during normal operation
This situation lasted until September 2011, when the International Physicians for the Prevention of Nuclear War (IPPNW) in Germany released a press notice. For the very first time anywhere in the world, half-hourly data on releases of radioactive noble gases from an NPP were made public.
This is shown in the chart (above right) for 7 days in September 2011. These data were from Gundremmingen NPP -in Bavaria, Southern Germany.
The chart showed that the normal emission concentration (of noble gases) during the rest of the year was about 3 kBq/m³ (see squiggly line along the bottom on September 19 and 20) , but during refuelling on September 22 and 23 this sharply increased to ~700 kBq/m³ with a peak of 1,470 kBq/m³: in other words, a spike.
Primarily, the spike includes radioactive noble gases and hydrogen-3 (tritium) and smaller amounts of carbon-14 and iodine-131.
This data shows that NPPs emit much larger amounts of radioactive noble gases during refuelling than during normal operation in the rest of the year.
From the new data, Nuremberg physicist and statistician, Dr Alfred Körblein, has estimated that, at its maximum value, the concentration of noble gas emissions during refueling was 500 times greater than during normal reactor operation. He also has estimated that about two thirds of the NPP's annual emissions occur during refuelling.
20-100 times dose increases to local populations
In May 2011 in Germany, Green MPs entered the Bavarian State Parliament (Landtag) for the first time where they formed the Government in coalition with the German Socialist Party (SPD).
After several requests, the new Bavarian Government insisted that the state nuclear regulator release non-averaged data on emissions. The highly reluctant nuclear regulator was compelled to respond.
In other words, the Green MPs obtained the data because they had the political power to force its release: there is a lesson here for British environmentalists.
So could these spikes help explain leukemia increases near nuclear plants? Yes they could. People living near nuclear power stations and downwind from them will be exposed to high doses of radiation during these emissions spikes - estimated to be 20-100 times higher than from the tiny releases during the rest of the year.
In 2011, the UK National Dose Assessment Working Group published guidance on 'Short Term Releases to the Atmosphere'. This stated that "...doses from the assessment of a single realistic short-term release are a factor of about 20 greater than doses from the continuous release assessment."
An older German study (Hinrichsen, 2001) indicated that these doses could be 100 times greater. (Hinrichsen K (2001) Critical appraisal of the meteorological basis used in General Administrative Regulations (re dispersion coefficients for airborne releases of NPPs) See Annex D page 9: Radiation Biological Opinion (in German).
A dramatic increase in individual doses
Some scientists think that the time pattern is unimportant and only the population dose is relevant, but this turns out not to be the case. The reason is partly related to the duration of the release, as short releases produce very narrow plumes (plume widths vary non-linearly as a fractional power of the duration).
The result is that individual doses increase dramatically per Bq emitted. Another reason is that spikes result in high concentrations of organically bound tritium and carbon-14 in environmental materials and humans which have longer retentions and thus higher doses.
The precise amount will depend on many factors, including source term, proximity to the reactor, wind speed, wind direction, and the diets and habits of local people.
Even before the new data, official sources didn't have a good handle on these doses to local people. Official estimates of radiation doses from NPPs already contain many uncertainties, that is, they could be many times larger than admitted.
This was shown in the 2004 CERRIE Report, a UK Government Committee which showed that dose estimates from environmental releases depended on many computer models and the assumptions they contained. The new information on radioactive spikes adds to these uncertainties.
Therefore higher doses from emission spikes could go a long way to explaining the increased incidences of child leukemias near NPPs shown by the KiKK findings.
'Especially at risk are unborn children'
IPPNW Germany warned of the probable health impacts of such large emission spikes. Dr Reinhold Thiel, a member of the German IPPNW Board said:
"Especially at risk are unborn children. When reactors are open and releasing gases, pregnant women can incorporate much higher concentrations of radionuclides than at other times, mainly via respiration. Radioactive isotopes inhaled by the mother can reach the unborn child via blood with the result that the embryo/ fetus is contaminated by radioactive isotopes.
"This contamination could affect blood-forming cells in the bone marrow resulting later in leukemia. This provides a plausible explanation for the findings of the KiKK study published in 2008 that under-fives living near NPPs are considerably more at risk of cancer, particularly leukemia, than children living further away."
In the light of the German data, it is recommended half-hourly emissions data from all UK reactors should be disclosed and that the issue of childhood cancer increases near NPPs be re-examined by the Government.
Nuclear operators should inform local people when they intend to open up their reactors, and they should only do so at night-time (when most people are indoors) and when the winds are blowing out to sea.
Dr Ian Fairlie is an independent consultant on radioactivity in the environment. He has a degree in radiation biology from Bart's Hospital in London and his doctoral studies at Imperial College in London and Princeton University in the US concerned the radiological hazards of nuclear fuel reprocessing.
Ian was formerly a DEFRA civil servant on radiation risks from nuclear power stations. From 2000 to 2004, he was head of the Secretariat to the UK Government's CERRIE Committee on internal radiation risks. Since retiring from Government service, he has acted as consultant to the European Parliament, local and regional governments, environmental NGOs, and private individuals.
See also Ian Fairlie's blog.