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by Tim Deere-Jones
Tim Deere-Jones dissects the UK Government's system for monitoring doses of marine derived radioactivity in food and concludes that the current programme is deeply flawed.
2013 has seen a major surge in the potential for expansion of UK nuclear power. In February, the Environment Agency (EA) found no objection to the discharge and disposal of radioactive wastes from a proposed nuclear power station with two CPWRs (contained pressurised water reactors) at Hinkley Point on the Somerset coast. It stated that the discharge of gaseous and liquid wastes to the marine environment and atmosphere of the Bristol Channel could proceed.
One month later the UK Government granted permission for the construction of the Hinkley CPWR, paving the way for a three-fold increase in the amount of some radio nuclides discharged to sea and also for the rolling out of planning permissions for another eight stations holding two or three reactors each.
In the same period, the Food Standards Agency (FSA), responsible for monitoring radioactivity in food, stated that, since “an annual monitoring programme has been in place for more than 25 years and no food safety risks have been identified during this period”, it now proposed to “optimise” the monitoring of radioactivity in food by reducing the scope and volume of its annual environmental monitoring and analysis programmes.
The FSA risk estimate for marine radioactivity is based on the outcome of assessment modelling of dietary dose, received from a range of foodstuffs thought to be representative of dietary exposure pathways. Here follows my review of the data inputs quality, upon which such modelling relies for its accuracy and relevance.
The original hypothesis for the behaviour of radioactivity in the sea
In the early 1950s, the first pipelines for the discharge of liquid nuclear waste to the UK’s coastal waters were commissioned. In the absence of empirical data, it was hypothesised that soluble radio-nuclides, such as Caesium or Tritium, would disperse and dilute through the water column and present no threat to human populations.
Insoluble nuclides, such as Plutonium, Americium or Cobalt 60, would adsorb to the outer surface of particles suspended in the marine water column, sink to the sea bed close to the point of discharge and remain immobilised in sub-tidal sedimentary deposits, sequestered from human populations and their immediate environment.
With support from the International Atomic Energy Agency, this theory provided the basis for the subsequent scientific, ethical and legal justifications for sea disposal of liquid radioactive wastes from nuclear sites. Its purely hypothetical nature was confirmed in 1958, when the UK industry and regulators publicly admitted that the sea disposal of liquid radioactive wastes had actually been an enormous research project.
Since the UK Government has not publicly revised or refuted this basic hypothesis, it remains the “official” position on the fate and behaviour of liquid radioactive waste discharges into UK coastal waters. No evidence gathered as a result of subsequent empirical scientific research has changed the basic position.
The monitoring programme
Annual reports such as “Radioactivity in Food and the Environment” (RIFE) published by the FSA and the EA state that most monitoring investigates the “local effects of discharges from nuclear licensed sites”, while there is “some ongoing monitoring of Chernobyl impacts”.
Historically, a small programme monitoring food and the environment “remote from nuclear licensed sites” was also carried out to give “information on background concentrations of radio nuclides”. This is what the FSA has proposed to abandon in order to “optimise” monitoring.
Based on the parameters proposed by the nuclear industry, the UK Government has focused its research on “near field” impacts close to the points of discharge, where the hypothesis proposed that radioactivity concentrations were higher and doses to the public greater.
RIFE statements that sampled fish are “indicator species” which “essentially sample the local water” have poor evidential support, as the majority of marine species caught at UK nuclear sites are migratory eg cod, mackerel. No evidence is supplied to prove that the sampled individuals had been resident in the area for any relevant period. Monitoring of less migratory species, or those living in close proximity to seabed sediments (e.g. grey mullet, flatfish) is uncommon.
Seafood “sampling observations” occur once a year, and generally consist of less than four, and most often one or two samples of each species. Such low numbers of observations cannot provide data on the frequent discharge “pulses” of certain radio nuclides that “new build” operators have been granted by the regulating agencies.
No details are provided of time of year, state of tide, ambient weather and water column parameters (all factors closely relevant to radioactivity concentrations in the marine environment being sampled). Thus the seafood monitoring programme lacks scientific rigour.
Marine sediment monitoring
It’s a basic principle of marine pollution science that fine sediments adsorb pollutants (like radioactivity) onto their outer surfaces. Because a given volume of fine particles has a relatively greater surface area than the same volume of large particles, it holds far higher concentrations of radioactivity than coarse particles such as sand, gravel, or cobbles.
However, during heavy seas or storm surges, fine sediments are remobilised, transported long distances through the marine environment and subjected to a range of mechanisms delivering doses of sea-borne radioactivity to “distant” human populations by pathways other than sea-food consumption.
UK marine radioactivity transfers to the land, contaminating coastal pastures and towns in episodes of coastal inundation. In onshore winds, aerosols, and spray generated by breaking waves, sea-borne radioactivity transfers from the surf-line to the land. Thus even if they have no direct contact with the sea or sea-food, coastal zone populations are potentially exposed to doses of marine radioactivity.
It is evident that research programmes should take account of these facts. However, my analytical review of the RIFE sediment monitoring programme at a typical UK nuclear power station (Hinkley Point) proves that it investigates only potential local effects, taking two samples from each of nine sites within 13 miles of the station.
Fine sediments, with the greatest concentrations of man-made radioactivity, consist of particles with grain sizes at, or below, 0.075mm. But RIFE reports fail to provide precise definitions of the “sediments” it samples. At Hinkley (2010) only two samples, taken from one site, are given a definition (mud) while the other 16 samples are not described. Apparently grain size analysis is not undertaken during sediment sampling. Such unquantified samples, taken annually, can only represent a very “brief period” spot sampling exercise.
Concentrations of radioactivity in sediments are moderated by a range of phenomena such as their position in the intertidal zone, the time of year samples are gathered, sea and weather conditions, winter erosion or summer deposition of sediments, and whether the same conditions are consistent across each site, each time samples are gathered. Annual monitoring reports fail to describe these parameters.
Thus the RIFE research cannot represent the entirety of seasonal and annual conditions, nor can it reflect the proposed peaks and troughs of “pulsed” intermittent discharges occurring when monitoring is not taking place. Therefore the sediment monitoring programme lacks scientific rigour.
Low numbers of radio nuclides analysed
Seafood and sediment monitoring regimes suffer another major weakness. UK nuclear sites routinely discharge a complex cocktail of up to 80 nuclides (depending on the type and performance of reactors). However, my analysis reveals that at no identified site is monitoring carried out for all, or even the majority, of the nuclides in the discharge stream.
The RIFE reports demonstrate that monitoring at UK nuclear sites generally fails to investigate the concentration of between 60% to 80% of the radio-nuclides discharged. This is justified on the basis that non-analysed nuclides are not thought to pose a threat to human or wildlife health or are discharged at only low levels.
However, the adoption of such a position displays a lack of scientific rigour because there has been no major research effort to confirm that unlisted nuclides have no detrimental health effect, and much evidence to demonstrate that some of them decay to produce much more dangerous “decay products”.
Given the complexity of multi-nuclide discharges, a further cause for concern is the absence of investigations of toxicological issues such as synergistic, antagonistic and cumulative effects (between discrete radio nuclides and between radio nuclides and non-radioactive subjects).
Monitoring “distant” sites and sea to land transfer
Official mapping of the marine distribution of liquid Caesium discharges from UK sites proves that soluble radio-nuclides are easily detected in sea water hundreds of miles from source and also in coastal and estuarine fine sediments where concentrations may double relative to sea water. Such information plainly refutes the original proposal that “soluble” nuclides would dissolve and dilute to infinity.
There is also a small body of government agency and nuclear industry work, much of it reported in the annual RIFE reports, describing sampling and analysis of non-soluble nuclides in sediments in the northern basin of the Irish Sea, and at sites on the coast of Cumbria, the Solway coast of south-west Scotland, and Northern Ireland.
These studies confirm that coastal and estuarine fine sediment deposits up to 100 km distant from the Sellafield pipelines hold relatively high concentrations of Sellafield derived insoluble radioactivity (Plutonium and Americium). This refutes the hypothesis that such nuclides would be immobilised in sediments close to points of discharge.
A 1982 study by the Atomic Energy Research Establishment confirmed the sea to land transfer, via sea spray and marine aerosol pathways, of highly enriched concentrations of Plutonium (Pu) 238, Pu 239, Pu240 and Americium 241 and, at slightly enriched concentrations, the soluble nuclide Caesium 137. This study estimated a dose to the public, by these pathways, from the four insoluble nuclides but excluding Caesium 137.
This, and similar calculations have subsequently been referenced many times as the scientific justification for claiming that such pathways “give rise to only very minor radiation exposures to the public”. However, the statement is deeply flawed because there is no justification for inferring that doses from the four insoluble nuclides represent the totality of doses from sea to land transfer.
The simple truth is that such studies usually focus on the four above named nuclides and never investigate the sea to land transfer potential of the remaining approximately 74 nuclides. Any general statement that total doses to humans from sea to land transferred radioactivity are “very minor” is not supported by empirical evidence.
The RIFE reports regularly reference low levels of sea discharged insoluble radio-nuclides in wild and cultivated terrestrial foodstuffs around estuaries on the Cumbrian coast up to some tens of miles away from the Sellafield site. They state that this occurs because of sea to land transfer by tidal or storm surge inundation, but also from the use of seaweeds as fertilisers.
It is generally not suggested that such results may result from sea-spray or marine aerosols. However, as with other sea to land transfer studies, dose estimates claimed to be very minor, are very inadequate because of the very limited number of nuclides analysed for.
In 1987 a Dyfed County Council (south-west Wales) report confirmed that Caesium from the Sellafield sea discharges, (over 200kms of coastline to the north) was found on pasture grass in excess of 10 miles inland having blown inshore on “sea spume”.
A dietary study in 1987 reported that residents of Kingsbridge in South Devon, a place believed to be “remote” from nuclear sites, consumed higher levels of dietary radioactivity (seven nuclides discharged from nuclear sites) in their local terrestrial food produce than a similar group living next to the Hinkley Point on the Somerset coast.
My review of this study found that the Kingsbridge dietary excess was due to radioactive Cobalt 60, transported (adsorbed in mobile sediments) from the Devonport nuclear submarine base 30 km distant by sea and then transferred from the sea to the land where it contaminated the terrestrial foodstuffs.
A 1991 study, published in the British Medical Journal, reported that the island of North Uist (Western Isles of Scotland) was saturated with sea to land transferred Caesium 137, from the Sellafield sea pipelines (over 200kms away). The Caesium had contaminated island dairy produce, meat, vegetables and pasture grass.
Islanders who ate the highest percentage of locally grown foodstuffs had the highest body burdens of Caesium and the average islander’s dietary dose of Caesium 137 alone exceeded the average dose (from multiple nuclides) to individuals living close to some nuclear sites.
On the basis of this review it’s my conclusion that the current programme for monitoring doses of marine derived radioactivity in food lacks the appropriate scientific rigour. It is not fit for current purpose because, owing to the weaknesses described above, it cannot provide sufficiently detailed data to justify the FSA claim that there is a “low risk from radioactivity in food” and that “no food safety risks have been identified”.
In that context, the FSA’s proposal to “optimise” the monitoring programme by “reducing background monitoring away from nuclear sites” while continuing to “monitor food around all licensed nuclear sites” is not a viable proposal for monitoring in the context of the proposed future expansion of nuclear power, and radioactive waste discharges to sea, in the UK.
On the contrary I would urge the FSA to adopt a more stringent and intense monitoring programme. This should comprise a higher number of sampling observations, analysis for a greater number of representative isotopes, a more intensive study of “far field” sites (such as island and coastal communities), a more intensive link between sample gathering and the “peaks” of pulsed discharge, and more intense research into both the dietary and inhalation impacts of the sea to land transfer of radio-nuclides and the contribution of marine radioactivity to coastal zone terrestrial diets.
Since the 1980’s, Tim Deere-Jones has worked as an independent pollution consultant on some of Europe’s major marine environmental incidents. Over the last three years he has represented the UK and Northern Ireland Nuclear Free Local Authorities (NFLA) on marine issues related to the UK Nuclear New Build programme.
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