In the context of the ongoing contamination of the marine environment following the multiple meltdowns and loss of coolant from the Fukushima site I note the ongoing near-site monitoring of the marine environment (sea water) and of some marine environmental media (principally fish, with some marine algae).
However I am deeply concerned to note that a number of highly relevant issues and phenomena relating to the behaviour and fate of the Fukushima sea discharged radioactivity and its potential for delivering doses to human populations remain un-recorded, under researched and/or completely ignored.
Thus it is evident that the true impacts of the radioactive contamination of the Japanese east coast are not being documented or acted upon.
The short, informal briefing, set out in the following pages, identifies and comments on some of those issues and introduces the outcome of a number of UK observations and studies (principally carried out in one of the planets most radioactive sea areas: the Irish Sea and itâs adjacent waters) in order to provide some supporting background information in support of my concerns relating to the Fukushima case.
Marine Radioactivity Consultant
N.B. Input of the search term âTim Deere-Jones: Marine Radioactivityâ to most of the popular search engines will upload links to a number of fully referenced, scientific and technical reports and studies, on the behaviour, fate and doses potential of marine discharged radioactive wastes in UK and European waters, that I have authored for a number of clients.
Issue 1: The number of radio-nuclides entering the marine environment of the east coast of Japan.
The currently operating marine environmental monitoring regimes in the relevant sea area are focusing on a very small number of radio-nuclides, principally Caesium, Iodine and Strontium which represent less than 10% of the total inventory of nuclides likely to be found in the reactor and cooling ponds of BWR nuclear power station (between 40 and 50)
Iâm pretty sure that this is happening because of the relatively high costs of radiological analysis of samples. Having been involved in a number of field work campaigns which have involved raising funds in order to pay for radiological analysis I can confirm that the cost of analysis for caesium (for instance) are much lower than those of analysis for plutonium or tritium.
In the case of independent and self funding green groups and NGOs with limited resources this is both understandable and acceptable practice. However, in the case of national governments, government funded environmental protection agencies and nuclear industries, under whose watch a disaster of this magnitude has occurred, I can see no justification for refusing to investigate the concentrations of approximately 90% of the radioactive material (all of which are capable of contaminating environmental media and delivering doses of radioactivity to wildlife and human populations) that may have entered the marine environment
Issue 2: The nature of the radio-nuclides derived from reactor and cooling pond outputs:
Iodine is formed in fuel elements and would only be present in (coolant) discharges as a result of fuel cladding defects and or fuel pin failure.
Caesium is a fission product and is also present in coolant as a result of fuel pin cladding defect or failure.
The presence of both Iodine 131 and the two isotopes of Cs, demonstrates that fuel pin cladding defect and/or fuel pin failure has occurred.
If this is the case then there can be little doubt that a range of other isotopes including actinides/ alpha emitters (probably 4 or 5 isotopes of Pu, 3 of Uranium, also Americium and Curium) will also have been released and entered the marine environment.
NB as stated above, one would expect the total inventory of a BWR to consist of 40 to 50 isotopes of various nuclides.
Fate and behaviour of marine radioactivity:
Some nuclides tend to dissolve relatively easily and in seawater; Caesium, Tritium and Iodine are an example.
Other nuclides have a low solubility and are preferentially adsorbed onto the surface of particulate matter suspended in the water column. These sediments will in time settle and accumulate in sedimentary deposits such as sub-tidal and inter tidal and estuarine mud flats: (fine sediments, with their larger surface area, will accumulate more than coarse sediments : thus muds will have far higher concentrations than sands).
However finer sediment particles are more susceptible to suspension in the water column than larger/coarser sediment particles and subsequent longer term transport before becoming deposited in estuarine and coastal environments.
Caesium, Iodine and Tritium :
Highly soluble nuclides become well distributed through the water body and concentrations generally appear to dilute with distance from source. However, a number of mechanisms of re-concentration do exist. In marine, coastal and estuarine environments.
UK studies in the Irish Sea have demonstrated that Caesium concentrations in marine sediments may be concentrated, relative to those in ambient seawater, and enriched by factors of two or three time in marine aerosols and sea sprays generated in both open water and at the surf line.
Cs concentrations can be shown to be enhanced through marine food chains relative to sea water concentrations and indeed through coastal zone foodstuffs (impacted by sea spray and marine aerosols) relative to adjacent ambient sea water concentrations.
Caesium and mainland coastal environments:
Irish Sea Caesium, derived from Sellafield liquid discharges to sea, has been found up to 10 kms inland in (south west Wales) in pasture grass and hence available for dietary dose delivery to human consumers via the dairy and meat food chain pathways.
Further implications of this study are
1: that the Caesium must be similarly contaminating any arable of horticultural produce grown in the relevant area
2: that since the Caesium must be blown inland from the coast then it is available for inhalation doses to the populations living at least up to 10kms inland
The south west Wales sample sites referred to above where not only 10 kms inland but also over 100kms distant by sea from the source of the Caesium.
Caesium and island communities:
Irish Sea Caesium from Sellafield liquid discharges has been found in the entirety of a Hebridean island local food production having transferred from the sea to the land in sea spray and marine aerosols generated in both the open sea and the coastal surf line by winds from many directions
The highest, individual, dietary dose was received by a terrestrial produce eater who did not eat fish, but did eat island grown vegetables, dairy and meat and only a small volume of âoff islandâ (imported) produce. This was a most important observation because it demonstrated that it was possible to receive a greater dietary dose of MARINE radioactivity through terrestrial foods than through sea foods.
The average dietary dose of the sea borne Caesium alone, received by the island population was higher than the average dietary dose of sea borne radioactivity from multiple nuclides/isotopes (up to 10) received by some populations living adjacent to UK nuclear waste sea discharge points. The island in question was over 200 kms (by sea) from the source of the discharged Caesium.
These two examples provide evidence of both sea to land transfer and dietary doses at DISTANCE from discharge point and point to the strong likelihood that other water soluble radioactive materials will behave in a similar fashion.
I have found no evidence of any studies of this phenomenon for any soluble material other than Caesium, but the available evidence strongly implies the potential for doses of iodine and tritium (and others), because they too are soluble.
In the context of these terrestrial doses it is evident that thereâs a potential for inhalation doses of Caesium, Tritium and Iodine, both from sea spray, marine aerosols, evaporation from coastal mud flats etc.
Non soluble (adsorbing) nuclides on the other hand are strongly susceptible to reconcentration mechanisms;
1: Irish Sea Plutonium (Pu) and Americium (Am) are shown to become enriched in marine microlayers relative to bulk seawater by factors of about 4
2: Pu and Am shown to become enriched in marine aerosols (generated by bursting bubbles) by factors ranging up to 600 relative to bulk seawater. These aerosols are airborne and readily cross the surf zone and penetrate inland
3: such enrichment mechanisms are found in the context of relatively high sedimentary (fine) particle loadings of the ambient water column.
4: âadsorbingâ actinides such as Pu and Am are also highly susceptible to re concentration in fine sediment deposits, thus, even at distance from input source, they may be found (in mud flats etc ) at concentrations several hundred times higher than those observed in
a: ambient sea water samples
b: less fine coastal sediments found much closer to the source of the discharge
5: inter tidal fine sediment deposits may provide a source of readily air mobile fine sediments (in drying conditions with effective winds) with adsorbed, and elevated concentrations, of actinides. Such conditions offer the potential for additional sea to land transfer of actinides.
6: strontium is similarly insoluble and thus there is a strong possibility that it has the same behaviour/fate characteristics as the alpha actinides referred to above.
Coastal geomorphology and coastal inter-tidal and sub-tidal sediment deposits:
I note that satellite imagery of the Pacific coast of Japan (Fukushima Prefecture) shows an area of relatively shallow and turbid (high suspended sediment load) water extending off shore for about 1 to 2 kms/ along the relevant stretch of coast
I note the presence of a number of rivers running down off the high ground inland, across the relatively narrow coastal plain and into the sea. I postulate that (in the wet season) these rivers will make a fairly high fine sediment (clay and organic mineral) contribution to the coastal water sediment budget. Such sediments are particularly prone to the adsorption of actinides
Iâve not yet accessed data about the local inshore currents along that stretch of coast. However I can confirm that the general offshore water body movement along the Pacific coast (Kuro Shio current) trends north during the northern hemisphere winterâ¦
Satellite imagery of the relevant coast also shows the presence of some significant embayments 50 kms + to the north of the Fukushima Daichii plant outfalls.
Both Matsushima Bay and Ishinomaki Bay are extensive and characterised by high sediment loadings and sediment deposits.
Such environments have the potential to be long term deposition sites for any actinide/alpha emitter present in âupstreamâ (ie northward moving) environments.
Itâs my conclusion that the official monitoring regime being carried out by TEPCO and other Japanese agencies is inadequate to the task of identifying the potential radiobiological threats to the public.
They are under-measuring both in terms of nuclides and the number and type of samples they are investigating because they have failed to pursue the issue of Iodine and Caesium production to itâs logical conclusion, which is that fuel failure also leads to the production of alpha emitting actinides which must also be present in the environment (note the Pu found in â
oolsâ adjacent to the NP station)
As nuclear industries, pro nuclear governments and their nuclear regulators always have done, they over represent the issue of dilution and dispersion
As nuclear industries, pro nuclear governments and their nuclear regulators always have done, they under represent the issues of re-concentration, transport, transfer from one environmental media to another and pathways of delivery to human populations
Further to weaknesses in Japanese marine environmental monitoring:
**Also relevant to note that a severe storm surge event in Liverpool Bay (UK) caused heavy flooding of coastal town during the course of which large quantities of marine sediments were carried into the town and deposited in the streets, gardens and houses. This material was heavily contaminated with actionable concentrations of man made radioactivity ( significant quantities of Americium were recorded).
Has any one bothered to assess the baseline data such as the quantities of man made radioactivity that may have been present in the coastal muds of FUKUSHIMA prefecture as a result of historical discharges from Fukushima NPs prior to the tsunami?
Has any body attempted to identify just how much of that (pre tsunami) radioactivity offshore of ALL the pacific facing Japanese NPS?came ashore with the Tsunami inundations?
Some notes distributed to colleagues and fellow campaigners in July 2012 (but still relevant: especially in the context of the current rising levels of radioactivity recorded at sea off the Fukushima plant)
In the context of the existing Pu discoveries and the inevitability that Pu and other alpha emitters will now be entering the marine environment: I offer the following
Given the intense use of ad hoc, large volume inputs, of cooling water from a variety of sources, coupled with the inability to control/contain ad hoc cooling waters as a result of the Tsunami damage inflicted on the site infrastructure (drainage, binding, pumps) it is inevitable that much of that ad hoc coolant will have entered unprotected soils and drainage channels and that there will be an extended time lag before all of it has drained into the sea.
Any future rain fall will wash any surface contamination (eg: undiscovered Pu puddles, deposits on buildings and other surfaces etc) into unprotected soils and drainage channels with similar extended time scales for marine contamination
The evidence to date suggest that the currently identified marine contamination is both the early stage and the tip of the future iceberg
It is inevitable that there will be transport (and subsequent deposition) of long lived in-soluble nuclides into intermediate and far field fine sediment deposits along the east coast of Japan, where significant degrees of re-concentration may be expected and reservoirs or âsinksâ of in-soluble radioactivity will be created
It is inevitable that there will be sea to land transfer of both soluble and in-soluble forms of radioactivity, across Pacific coast surf lines and in to the Japanese terrestrial coastal zone, with subsequent potential; for deliveries of dose via dietary and inhalation pathways. Such mechanisms may well deliver doses to areas and populations which have not been in receipt of (Fukushima accident) doses delivered by atmospheric routes.
(N.B. A recent desk review carried out by myself has demonstrated that:
a: the technologies used in attempts to quantify sea to land transfer are consensually agreed (by the authors of the relevant papers) to be unsuitable for quantitative analysis
b: only about 10% of the component nuclides in liquid discharge streams from NPS and Reprocessors have actually been studied in the context of sea to land transfer mechanisms)
Some Recommendations for action:
1: Itâs important to establish a base line for Pu and other alpha/actinide data against which to measure future concentrations :
2: Therefore those marine fine sediment depositionary environments (inter tidal and sub tidal) where actinide/alpha depositions will re-concentrate isotopes SHOULD BE MONITORED and ANALYSED NOW (local and regional estuarine mudflats and salt marshes and âfar fieldâ Matushima Bay, Ishinomaki Bay) otherwise at a later date it could be claimed that any contamination was from another source (eg weapons test or even Sellafield!)
3: Similarly, coastal zone terrestrial zones (outside the known aerial fallout zones) should also be examined in order to generate data which could be used to provide baseline info against which to measure sea to land transfer and related phenomena ( terrestrial produce contamination, house dust contamination etc.
4: Same could be said for Caesium, Tritium and Iodine
5: A useful exercise re Pu and other alpha/actinides and Strontium might be to filter seawater and analyse clear water and sedimentary material separately in order to assess
a: potential sea surface microlayer and aerosol enrichment factors
b: potential for future sedimentary deposit concentrations
There is a stated assumption that marine environmental concentrations will soon decline: and that concentrations will âsoon be of no concern due to the short half lives of nuclides mentionedâ. This is not true of the Caesium isotopes measured (half life approx 30 years). It is even less true of the alpha/actinides which will be present in the marine environment for very long time spans which must be measured in the hundreds of years (and in some cases the thousands of years).
Itâs imperative (for the slightly longer term) to initiate action to facilitate the identification of
1: all possible post accident marine radioactivity exposure/dose pathways
2: all potential, post-accident, marine radioactivity, near field, intermediate field and distant field Critical Groups
I define Critical Groups as:
those populations most likely to be exposed to the highest doses from these sources and pathways as a result of
a: their habitation of particular areas and zones
b: their consumption of sea foods
c: their consumption of terrestrial foods contaminated by sea borne radioactivity as a result of sea to land transfer
d: their inhalation of sea borne radioactivity suspended in and being transported through the coastal zone aerial environment as a result of sea to land transfer."
Tim Deere-Jones Report; Marine Fukushima Radioactivity In Sea Water; via @AGreenRoad