Aberdeen Beach Radioactive

This version 30 March 2007.
Minor modifications 26 April 2007
Detailed information and references have been added on 27 April 2007.

Since March 2003, there have been reports of enhanced radioactivity on the southern end of Aberdeen Beach, known as Foot Dee.
This was first reported by a member of the public.
The following report, summarises the information gained, and interpretations made, from my own investigations into the occurrence of this radioactivity.

This is agreed, by SEPA, to result from contamination of the beach because of material being washed onto the beach. It is not a natural feature of the beach. For a period of weeks in 2005, this part of the beach was taped off to prevent public access, whilst SEPA investigations occurred.

SEPA concluded that there is a nearby industrial operation in Aberdeen Harbour, who work at removing "scale" from oilfield equipment and pipework. This scale comprises minerals which are crystallised onto the interior of pipework when water fluids from the deep subsurface are produced during oil and gas production. This baryte (Ba SO4) scale is physically washed off the pipes , and then ground to a sand size, and disposed of by pipe into Aberdeen harbour. The scale is radioactive, and contains Naturally Occurring Radioactive Material (NORM). This industrial procedure has been allowed to legally occur since about 1987. This is because the previous operation on the same industrial site produced fertilizer, which is naturally very slightly radioactive, and a licence to discharge very low levels of radioactive substances was given. This licence appears to have been transferred to the new oilfield scale operation, on the basis that this also involves NORM. SEPA have proposed that the material on the beach is derived from fertiliser, and is of no public hazard, being extremely low in radioactivity.

However the discharge of radioactive waste into the sea, derived from land based operations and pipes, is now amongst many pollutants regulated by international conventions such as OSPAR (Oslo-Paris). Any discharge to the ocean must be tightly regulated. The UK is attempting to reduce discharges close to background levels of radioactivity by 2020. Consequently, SEPA have given notice to the company that they must cease discharge of elevated radioactivity into the sea by end 2008. An alternative disposal route must be found by the company. This is likely to be significantly more expensive. Some estimates state that very low level radioactive waste taken to a landfill licensed for radioactive disposal, costs £5,000 per cubic metre. The company is legally appealing against this SEPA restriction (Jan-May 2007).

I have examined several of the publicly available documents, and it is my opinion that the waste discharged is solid (being ground-up baryte and other minerals from scale), and is not a liquid as originally licensed to the industrial operator. The "liquid" claim seems to arise because the sand scale is flushed through the pipe into the sea as a water rich "slurry".

The SEPA opinion that radioactive contamination of the beach is due to fertilizer from old operations has been contested by a member of the public. An analysis of the scale and of the sand on FootDee beach has been undertaken by the British Geological Survey (BGS). This has examined 3 samples of scale and 17 samples of beach sand. Radioactive measurement has been undertaken by the Health Protection Agency. X-Ray Diffraction analysis (to determine approximate mineralogy), and X-Ray Fluorescence analysis (to determine atomic chemical makeup) have been undertaken and reported by the BGS. These analyses have been re-interpreted by a member of the public, who claims that the material on the beach is of oilfield scale origin, with very minor fertilizer. I have examined both the BGS and the public document, and am in full agreement that radioactive oilfield scale is abundant on FootDee beach. This scale is strontium rich baryte of variable exact composition (as is common with many minerals). It also contains natural radioactive elements which have been concentrated during the mineral growth in drill pipe.

This scale emits significant radioactivity. Counts of up to 40 Bequerels per gram were recorded in the BGS report, and significantly these are for radium 226 - which is an emitter of Alpha particles, within the decay series of uranium. Additional radioactivity comes from the Actinium 228 content, which produces Beta particles from the thorium decay series. Gamma energy is also emitted from both decay series. The beach sand is also radioactive, but less than the scale. Counts of up to 6 Bequerels per gram radium 226 have been measured. About 12 of the 17 samples taken were radioactive. I do not agree with SEPA that this is an insignificant hazard.

It is my opinion that some of the scale has moved from the discharge pipe, and northwards onto the FootDee beach. This is supported by an experiment funded by the industrial operator, where tracer material was released from the pipe outfall. The pipe emerges into the sea on the north side of the north harbour wall, ie only several tens of metres distant fromt the public beach. This tracer was detected on the beach north of FootDee, and on the beach at Nigg to the south of the discharge site, within a very few days. This confirms the potential for material to move from this industrial discharge pipe and onto the beach. Calculation, by a member of the public, used the mineral analyses of the radioactive sands to show that there is a significant content of scale in the radioactive beach sand samples (tens of percent content in some cases). This can be found on the SEPA website. It is my opinion that the nearshore water currents have moved radioactive solid sand from the discharge pipe, and re-concentrated the radioactive sand on FootDee beach. This is particularly concentrated beneath the high seawall protecting FootDee village at the south end. It is very clear, that the intended objective during waste disposal to Dilute and Disperse the waste, has partially failed, and that some waste has become physically concentrated by natural processes. The measures of radioactivity in these beach samples, combined with the estimates of scale content from the mineralogy, can be interpreted to show that radioactive particles are present in the beach sand, with activities identical to that treated as a radioactive hazard within the industrial operation. The overall radiaoctivity of beach samples reaches a maximum of 6 Bequerels per gram radium 226, showing that dilution has occurred.

However this radioactive sand emits alpha particles. If the radioactive material is eaten, these are 20 times more dangerous to people than Beta particles. In UK legislation, and procedures for power station waste, radioactivity greater than 0.37 Bq/g for radium 226 is sufficiently high to become of interest to regulators, because of its potential hazard. Alpha particles are stopped rapidly by air, skin or water. Thus there is minimal actual danger to a person unless sand is eaten, or dust is breathed in.

If this beach sand material were derived from a nuclear industry operation, the level of radioactivity present would fall clearly into a definition of Low Level Waste. This would require special handling, and storage, followed by eventual disposal to an authorised landfill site. Such waste would not be permitted to be disposed into the natural environment.

In simple terms, the maximum un-regulated level of radioactivity allowed for radium (producing alpha particles) is exceeded by up to 15 times in many bulk samples of Foot Dee beach sand. Because the particles seem to be derived from crushed scale, of known activity, and are diluted into sand of known activity, it can be calculated (but has not been directly measured) that the bulk beach sand probably contains individual particles which are 100 times more radioactive than the lower regulatory limit of radioactivity for radium alpha particles. Discharge from an industrial site may be agreed by SEPA, assuming Dilution and Dispersal to sea, but now some of that radioactive sand has accumulated, and been detected, on a public beach.

Several hundred tons of sand seem to be affected, although there is no public information to assess if the beach has been surveyed for radioactive particles northwards. The half life of radium 226 is 1,622 years. So this contamination could last a very long time. It is possible that sea water currents will move the radioactive sand gradually along the beach and offshore to disperse the radium into low levels in the natural environment. However this is an unproven process, and the rate of any removal of dense radioactive sand during the forthcoming 20 or 40 years is unknown.

It should be emphasised that this radioactivity is at the low end of Low Level Waste. In terms of hazard to the public, there will be minimal risk from alpha particles unless these are eaten or breathed in. The overall risk is perhaps 100 times less than driving a car. However, this level of radioactivity is clearly in excess of background level. It is also important to realise that these radioactive partciles are individually much much less active than those found near Dounreay for example (more than 10,000 Bq per particle), and are natural radioactivity, not from fuel rods or the like.

As an estimate, the Health Protection Agency information leaflet on NORM states that eating one third a cup (80ml) of NORM scale would double the yearly dose of an individual person. To fit with UK regulations on dose being less than 0.3 milli Sieverts (300 micro Sievert) from a single source - that would equate to an adult person eating about 10 cm3 of pure NORM per year. To comply with EURATOM guidance on "optimised" doses, then 0.02 milliSieverts per year could be taken as a cautious ambition for the adult public. That would be about 1 cm3 of pure NORM per year - about a sugar cube volume. The extra statistical risk of this last example small extra dose is small compared to daily life. That is about 1 in a million death rate, or similar to the risk from one chest X-Ray, or 3 times less that the radiation from a return transatlantic flight. If more sand was eaten, then the statistical risk obviously increases. The risk also increases for children and infants, who could be at much more risk than the average adult. I do not see evidence that SEPA have calculated the risk to these types of people, or that SEPA have taken a precautionary approach to this much-used beach in the centre of a city. Following 30 March, a helpful meeting with SEPA has taken place, and their calculations of radioactive dose have been made available. These show doses greater than my initial estimate, but which are less than the international 0.3 mSv reference maximum. However the doses are greater than the international recommendations for the public dose where there is no societal benefit, and about 10 times greater than the dose from this same NORM material after radioactive waste disposal in a planned and engineered landfill. It is apparent that the UK legislation is not prescriptive and enables regulators to choose larger or smaller levels of dose in different cases, which may not coincide with internationally recommended best practise. This is discussed on the page of detailed information and references.

On 26 March 2007, I visited the beach, with a ratemeter which can detect radioactivity from surfaces. This will inevitably be dominated by Beta and Gamma radiation, because Alpha particles do not travel far in air. At the roadside, on the southeast end of the Esplanade, background radiation is slightly elevated - 12 counts per second rather than 8. Moving down onto the beach, then counts increase to 15, rapidly becoming 20 along the foot of the seawall. Moving south towards FootDee along the base of the sea wall, then counts increase to become 40/second (ie 4 times normal background). At the southern end of the high seawall, where this is replaced by boulders, the counts reach 150/second on the beach surface. This is very abnormally high for a public area. Beneath the main east-west harbour wall, no excess radioactivity was detected. At the low tide level, no excess radioactivity was detcted. The enhanced radioactivity on 26 March 2007 was close to or above high tide level. Samples of the most radioactive sand were taken to be dried, and measured indoors by a detector specific to Alpha particles. This detected a high count of Alpha radiation from these samples. This is field measurement confirmation of the samples analysed by the British Geological Survey and measured by the Health Protection Agency. There appears to have been no reduction of radioactivity from 2003 to 2005 to 2007.

My recommendations are that

Stuart Haszeldine
http://www.geos.ed.ac.uk/homes/rsh/Aberdeen_Beach_radioactive.html

There is now a BBC Scotland report on this http://news.bbc.co.uk/1/hi/scotland/north_east/6504431.stm See the next page to show where the polluted sand was found

Following several queries and comments, an additional page with more detailed information and references has been added on 27 April 2007.

In conclusion