School of GeoSciences

School of GeoSciences

Aberdeen Beach radioactivity detailed information

SUMMARY of research investigations by Prof Stuart Haszeldine.  Posted 27 April 2007

• Foot Dee beach contains pollution from Naturally Occurring Radioactive Material, originating from a discharge only tens of metres away.
• Levels of radioactivity in Foot Dee beach sand, are well above the levels at which regulators become involved.
• The radioactive material is much, much, less radioactive than fuel particles at Sandside beach.  But at Foot Dee there are many, many, particles - so exposure to some additional radioactivity is guaranteed.
• If this sand were transported off the beach, it would be classed as Low Level Radioactive Waste.
• SEPA are uncertain how this radioactivity arrives at the beach, about how much radioactive material is present on the beach, and about how it will disperse.
• International standards recommend a very low radioactive dose to protect the public
• The dose calculated by SEPA exceeds the internationally recommended minimum by 16 times
• SEPA have not stated that there is no risk to the public at Foot Dee.
•  This dose can be permitted by interpretation of UK law, but that is more lax than international recommended aspirations.
•  SEPA calculations suggest a risk of death is 1 in 100,000 for an adult, exposed by being on the beach for many hours
•  Children and infants could receive larger doses than calculated by SEPA, by eating sand - just one sugar cube volume exceeds international recommendations.
•  A remedy, in line with international recommendation, is to place information notices on the beach. 
    This can enable the public to adapt their behaviour and greatly reduce their personal risk.
• Foot Dee may be the most radioactive public beach in the UK.
• Foot Dee beach is much more radioactive than discharges from nuclear power plants.
Simpler introductory information is at http://www.geos.ed.ac.uk/homes/rsh/Aberdeen_Beach_radioactive.html

REPLIES TO COMMENTS RECEIVED
References at base of this page


1) The scale is significantly radioactive
The UK level for radioactivity of regulatory interest is 0.37 Bq/g for solid material containing radium, and for several other radionuclides (1).  NORM (Naturally Occurring Radioactive Material) scale is frequently at 40 Bq/g activity (2).  The scale at Aberdeen beach arises from decontamination of oilfield equipment by a company in Aberdeen. It is my understanding that protective equipment is required in those operations, and that a licence to discharge radioactive material has been required.  It is therefore apparent that this scale is regarded by regulators as significantly radioactive. 

2) This radioactivity emits alpha particles
It is a matter of record, in a report by the British Geological Survey (3),that alpha and beta particles are detected in the scale, and in samples of the beach sand.

3) these are 20 times more dangerous than beta particles
This is an accepted figure for the weighting factor of the absorbed dose (4). Obviously, as explained elsewhere, that full dose requires ingestion of some radioactive material.

4) it is probable, but has not been directly measured, that these particles are 100 times more radioactive ( ... than Foot Dee beach sand .... ).  
This is an arithmetic calculation, based on the measured activity of the scale and the activity in samples of beach sand diluted by non-radioactive material.

5)  typically for very low level radioactive waste taken to a landfill licensed for radioactive disposal, costs can be 5,000 per cubic metre. 
Cost estimates are derived from a UKAEA document (5).

6) references to a member of the public. 
This person has submitted information which is publicly available on the SEPA website (6).  The calculations are self-evidently highly plausible, irrespective of their authorship.  The person has asked to remain anonymous.  I have no reason to doubt their competence in the information they have provided.

7)  OSPAR has not prohibited the operational discharge of radioactive material.
The OSPAR treaty (7) specifically includes NORM (Appendix 3).  There is a distinction in the treaty between material arising and disposed of offshore, and material arising on land, even if derived from offshore.  The focus of the present discussion is on waste material which has arisen onshore.  The Radioactive Substances Strategy of this treaty has an aim that the signatories (including the UK) are committed to “the ultimate aim of concentrations in the environment near background values for naturally occurring radioactive substances”.  The definition of discharges covered by OSPAR includes “ offshore pipelines from which substances or energy reach the maritime area".   The UK has a DEFRA policy that OSPAR “should be completed within the agreed timeframe”, which is stated to be 2020 (8).  OSPAR does not prohibit discharges to the sea, but those must be rigorously monitored, and the aspiration is to reduce all discharges to background levels.

8) Two references … 0.37 Bq/g for radium 226 ……  minimum allowed radioactivity for alpha particles ….
It is agreed that the original wording of “safe lower limit for radium 226” does not communicate the intended information. This has been altered to “radioactivity greater than 0.37 Bq/g for radium is sufficiently high to become of interest to regulators, because of its potential hazard”.

The original sentence “many samples of beach sand are 15 times more radioactive than the minimum allowed radioactivity for alpha particles” can potentially be read in different ways.  For greater clarity this is changed to “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”.   

It is also noted that the activity of Foot Dee beach sand places it within the LLW (Low Level Waste) category, as alpha emitting material is not included in the definition of VLLW for “dustbin disposal” to landfill (9).  Some public information is un-specific about this distinction between alpha emitting and beta emitting waste.  There is even a suggestion (10) that double standards have evolved in Europe, perhaps unintentionally, for NORM versus artificial radioactive substances.

9)  Several hundred tons of sand seem to be affected
The surface expression of enhanced radioactivity at Foot Dee is elongate parallel to the sea defences, and located around the high tide mark.  This material constitutes several hundreds of tons of sand.  Suggestions that storm events may remove NORM can not be supported either for, or against.  At present there is (according to SEPA (11)) a detectible quantity of fertilizer in this sand, which is interpreted to originate from discharges from the industrial site over 20 years ago. Therefore the existing evidence shows that radioactive material (fertilizer) has persisted on this section of beach for over 20 years, making it quite possible that NORM will remain for a similar period.  Additionally, there is a low barrier wall running parallel to the sea defences, but often buried beneath sand (18).  This is considered to have potential to act as a trap for mobile sediment.  It is quite possible that the wall has enabled hydrodynamic concentration of dense NORM radioactive scale material by storm wave winnowing, and that radioactivity may increase landward of the wall.  This is the opposite of suggestions that storms will remove the dense radioactive sand.

SEPA initially stated that radioactivity on the beach was due entirely to previous discharges from fertilizer processing.  However, following new evidence submitted (6), SEPA have now agreed that significant NORM occurs on Foot Dee beach (11)

10) Dispersion study
Tracer particles of similar size and density to NORM were released from the discharge pipe on 13 April 2005, and samples from the beach were collected during the following days, to identify if anyof this material returned to the beach (19). The study does conclusively show that sand-sized material, which is released from the discharge pipe, several tens of metres from Foot Dee beach, can be transported to the beach within a few days. This single study is not a good method to quantitatively determine the overall motion of NORM particles during the yearly wave and tide cycles.  Although the general motion of sand particles is supposed, historically, to be northwards along Aberdeen beach, it remains un-clear at what rate this occurs, and what pathway the sand takes.  The uncertainty of sediment movement is demonstrated by the erosion of Aberdeen beach in the past decades and years.   Dredging of harbours can often promote erosion of nearby beaches - though that is speculation at Aberdeen.

11) Context and risk assessment
The risk from the radioactivity of beach sand is a matter for a calculation of dose to a “critical group”.  That involves exercise of judgement as well as standard practise.  The overall risk appears to be lower than many common, but significantly dangerous, activities like driving a car – such analogies are made to aid communication. 

However it cannot be said that there is no risk, and SEPA have noticeably not made such a statement.  The dose, and hence risk, can be calculated by several exposure routes:
a)  My own estimate of dose, and hence risk, was based on extrapolation from (2), and produces a lower result for adults compared to the more sophisticated calculations.
b)  SEPA have calculated (12) a combination of individuals residence time on the beach, with minor ingestion and inhalation.  This gives an adult dose to an individual of the critical group of 167 micro Sievert per year.
c)  SEPA have also calculated a dose by ingestion (12).  This can result in a 1,000 micro Sievert (1 mSv) dose to a “critical group” infant by eating 50g of sand.  However it is unclear why a dose of 300 micro Sievert has not been chosen, as the dose constraint normally used as appropriate for a single source of radioactivity – this would result from just 15g sand ingestion.  It is notable that declarations to OSPAR by UK facilities take the more rigorous 300 micro Sievert as the appropriate annual dose (13) rather than 1000 micro Sievert.
d)  There are proposals to construct a landfill to dispose of this NORM waste in future, instead of disposal into the nearshore ocean.  These proposals base their performance calculations of safety on a dose target of 20 micro Sievert per year to an individual (14).
e)  The ALARA (As Low As Reasonably Achievable) principle has as its lower limit a dose of 20 micro Sievert per year, and UK regulation has this as its ambition for operational facilities (14, 15) by 2020.  It is not clear why international guidelines are not followed by SEPA to reduce public risk.

Expanding on the above:
ai) An estimate was made because the full calculation of dose is highly complex, depending on the radionuclides and on the summation of individual body organs.  My estimate calculated that adult ingestion of about 1cm3 of pure NORM would produce an additional dose of 20 micro Sv, ie an additional risk of death of 1 in 1,000,000.

bi) This dose to the public is exceptionally high, when compared to a compilation of doses to the public from UK radioactive sites reported to OSPAR (13).  Many doses from operational nuclear sites are 5 or 10 micro Sievert.  A comparable dose to Foot Dee is only obtained in the UK from Sellafield, and that exposure route envisages substantial consumption of contaminated food.  By contrast the Foot Dee dose calculated by SEPA is involuntary, is received mainly by simply being on the beach, and is located in a public and exceptionally popular place.  It seems possible that Foot Dee is the most radioactive public beach in the UK.

ci) The ingestion exposure route is, to some extent, a matter of behaviour judgement.  There are standard typical habit data for radiological assessment, which can aid or guide such calculations.  This exposure route is particularly relevant at Foot Dee, as this is a beach which is close to a children’s playpark, and a section of beach where children can and do dig in the sand.  Ingestion of 15g of sand during several beach visits is, in my opinion, within the bounds of possibility. This exposure route therefore could be given especial attention. To argue that only 5g or 10g may be ingested misses the point that the principles of ALARA and BPM point towards a high standard of protection for the public.  This exposure route can be greatly reduced by public information, so that public know this particular sand contains unexpected particles.

di) There at present is no clear disposal route in the UK for NORM waste derived from onshore operations, in spite of this problem being known for many years.  Special Precaution Burial appears now to be the preferred route (15).  It is noted that the design of such a facility takes 20 micro Sievert as the reference of public dose for its design (14).  Obviously, this is not the same as guaranteeing that levels of contamination will not exceed that limit.  However the same NORM material is present on Foot Dee beach in activities up to 6 Bq/g, which could result in doses of 167 micro Sievert per year to adults.  This translates conventionally (16) into a 1 in 100,000 risk of death. This has been known since 2003.  Because the NORM has been “disposed of” by the site operator, this un-intended beach accumulation has now become the disposal site for part of that NORM.  Because of the long half life for much of the radioactive material, the beach activity will only decrease by natural sand dispersion.  However there is evidence that some radioactive material has been present for over 20 years, so NORM could well remain concentrated on the beach for that timespan. Neither are the processes of concentration of the waste understood by SEPA.  It is quite possible that this level of radioactivity will persist for many decades into the future.  Logically, equally high standards of public protection should apply to this beach “disposal site” compared to a landfill site.  Similar public standards are not being enforced. 

ei) The ALARA (As Low As Reasonably Achievable) principle means that all reasonable steps should be taken to protect people, whilst also weighing costs against benefit.  The international Precautionary Principle notes that lack of scientific certainty should not postpone cost-effective measures.

Since 1954 the ICRP (International Commission on Radiological Protection) has recommended that “every effort be made to reduce exposures to all types of ionizing radiation to the lowest possible level” (17).  The ICRP recommend that additional dose to the public be as low as 1,000, 300, 100 or 10 micro Sv, depending on context.  The maximum risk constraint from a single source is recommended to be 10-5, ie 300 micro Sv (ref 17, p67).  The ICRP emphasise the need to justify and optimize the benefit to the public if greater radiation doses to the public are anticipated, with a maximum dose of 1,000 micro Sv (1 mSv/yr). This optimized reference level should take account of all exposure routes to the public – for example in the Grampian Region especially, the dose from radon in housing may still be significant for some individuals.  Consequently to adopt 1 mSv/yr as a reference level for Foot Dee alone is too simplistic. Where the exposure is prolonged to long lived radionuclides in waste disposal, the ICRP recommend a public exposure constraint of 300 micro Sv /yr (ref 17, Table 8, p78) as the upper bound on the dose.  If the dose is uncertain or verification is uncertain, the dose constraint could be as low as 100 micro Sv/yr (ref 17, para 253, p65).  Where individuals are exposed to a dose from which there is no societal benefit, then the ICRP recommendation is that dose should be less than 0.01mSv/yr, ie 10 micro Sv (17 para 232, and Table 5). ICRP state “exposure of members of the public from the planned operation of practices is a prime example of this type of situation”.  The maximum dose calculated by SEPA is less than 300 micro Sv, but more than 100 micro Sv.  Given the uncertainty in knowledge of the transport of particles, uncertainty in knowledge of physical concentration, and the knowledge the natural processes of particle dispersion are slow, my opinion is that the lowest ICRP limit should be chosen.

It is noted in the calculations (a, ai; b, bi and c, ci above) that these exposure routes depend on the behaviour of people.  A low cost intervention, consistent with ALARA, could be to provide people with information, and then individual choices can be made to modify behaviour.  In the particular circumstance of Foot Dee, one or more information notices could cheaply and easily provide public information that this section of beach is contaminated, whereas the sections of beach in the intertidal zone, and northwards beneath the Esplanade, are not significantly contaminated.  To avoid ingestion and other exposure routes the public, particularly children, could be recommended to not handle Foot Dee sand or habitually spend long periods on that section of beach.


12) Additional facts
• NORM discharge assessments and risk:  As explained in point 11, although these risks are low, it is not agreed that these risks are insignificant
• No breaches to disposal licence;  That is not the concern
• No alternative disposal options:  That is not the concern.
• Industry NORM management plan: The past, existing, and future contamination of Foot Dee beach will remain an issue of public exposure long after the oil industry has moved to less polluting methods.


Summary:
There is good evidence that significantly radioactive scale particles occur commonly on Foot Dee beach. These produce a 6Bq/g activity of bulk beach sand, which is well above the 0.37 Bq/g limit of radiation for regulatory interest.  There is a poor understanding of the concentration, and future duration of contamination. SEPA have chosen 1000 microSv/yr as their dose maximum, rather than a maximum dose from a single source of 100-300 microSv/yr. Where societal benefit is minimal, international standards recommend a dose reference level of 10 microSv/yr, and 20 microSv/yr is now being used to plan disposal facilities for the same NORM waste in landfill (14). SEPA calculate feasible exposure routes at Foot Dee which produce 167 microSv/yr doses to adult public; children and infants could receive greater doses from ingested material.  This exceeds international recommendations for a dose where there is no benefit to the exposed population.  This dose conventionally translated into risk of death or cancer is 1 in 100,000 of the population with that exposure route.  This is at the maximum dose limit recommended internationally for the public.  A simple remedy, aligned with the precautionary principle, is to erect explanatory or information notices, so that public can modify their behaviour and so eliminate the worst exposure routes. Disagreement remains about such a simple intervention, with SEPA refusing to recommend it.



Reference material:
1 Radioactive Substances Act 1993           http://www.opsi.gov.uk/ACTS/acts1993/Ukpga_19930012_en_1.htm
2 NORM in the oil and gas industries. National Radiological Protection Board information sheet 1999          http://www.hpa.org.uk/radiation/
3 Mineralogical and geochemical characterization of beach sand and scale samples for SEPA. British Geological Survey CR/05/207       Available from SEPA
4 eg p 43           http://www.sepa.org.uk/pdf/radioactivity/prospective_public_dose.pdf
5 Establishing dialogue and sustainable practices G. Linekar, UKAEA 2002 p22                  http://www.ciria.org/safegrounds/pdf/managing_vllv_appendices
6  Letter from consultees in consultation SEPA 2006 p11-26                http://www.sepa.org.uk/pdf/radioactivity/publications/scotoil/appendix_b.pdf
7 http://www.ospar.org
8 DEFRA aspirations for OSPAR               http://www.defra.gov.uk/environment/radioactivity/government/international/ospar.htm
9  CoRWM 2006 p22             http://www.corwm.org.uk/pdf/Chapter02.pdf  Also for example DEFRA 2005 Disposal Of Low Level Radioactive Waste From Non-Nuclear Premises
                 http://www.defra.gov.uk/environment/radioactivity/waste/pdf/smallusers.pdf
10 Recycling and NORM.   World nuclear association 2004          http://www.world-nuclear.org/info/inf30.html
11 SEPA 2006 Response to consultees comments Page 5 “Having reviewed the content of the new assessment of the data SEPA now accepts that, on the basis of the assumptions made, minerals associated with oilfield scale appear to contribute to a greater proportion of the radioactivity on the beach than minerals associated with fertilizer production.”
     http://www.sepa.org.uk/pdf/radioactivity/publications/scotoil/appendix_c.pdf
12  SEPA Sept 2005         Summary of updated dose assessment for Aberdeen Beach.   Obtained from SEPA
13 OSPAR Commission 2005 The Application of BAT in UK Nuclear Facilities Report.
             http://www.ospar.org/documents/dbase/publications/p00241_Imp%20Report%20PARCOM%20Rec%2091_4%20UK.pdf
14 SNIFFER 2005 Project UKRSR03 pp 10-11   The development of a framework for assessing the suitability of controlled landfills to accept disposals of solid low-level radioactive waste: principles.           http://www.sniffer.org.uk
15 DEFRA 2007 Policy for the Long Term Management of Solid Low Level Radioactive Waste in the United Kingdom.
           http://www.defra.gov.uk/environment/radioactivity/waste/pdf/llw-policystatement070326.pdf
16 Radiation effects at low doses Lawrence Livermore 2000            http://www.lbl.gov/abc/wallchart/chapters/appendix/appendixf.html
17 ICRP 2007               http://www.icrp.org/docs/ICRP_Draft_Recommendations_12_January_2007.pdf
18 Radioactive Contamination on Aberdeen Beach: B Tilly and A Hills presentation Feb 2006.               Available from SEPA
19 Scotoil outfall dispersion study, Aberdeen.  Report 05/J/1/12/0731 Sept 2005                  Available from SEPA