Particles in the environment
Background
Monitoring of beaches has been part of the routine marine environmental monitoring programme at Sellafield since 1983. Strand line monitoring along the area of tidal debris was undertaken via a walking survey using hand held instrumentation. In 2003 a radioactive particle was found during a routine survey, it was unusual in that it contained mainly Strontium 90 activity. Finding this particle prompted a review of beach monitoring and, as a result, trials of a large area monitoring technique were agreed with the Environment Agency. The trials were undertaken by Nuvia Ltd on behalf of Sellafield Ltd using the Groundhog™ monitoring system and proved successful in finding and removing a number of radioactive items from the beaches at Sellafield and Braystones. Following this trial Sellafield Ltd and the Environment Agency agreed a programme of large area monitoring on beaches from St Bees to Drigg Point. This was specified as a reporting requirement by the Environment Agency in their “Compilation of Environment Agency Requirements” (CEAR) document, under the Radioactive Substance Act 1993, Certificate of Authorisation.
As a logical progression to the requirement for large area beach monitoring, attention is now also being given to the offshore environment and understanding the potential for radioactive particles to be present on the seabed.
Health Advice
Advice from Health Protection Agency
The Health Protection Agency has been advising the Environment Agency on the risks associated with using the beaches around Sellafield.
In addition, the Food Standards Agency (FSA) has also been advising on their position regarding risks from consumption of seafood. In April 2011 the Health Protection Agency published their risk assessment, which is now available via their website. Copied below is the assessment synopsis:
"In 2007, the Environment Agency (EA) sought the advice of the Health Protection Agency (HPA) on the health implications of the findings of this beach monitoring and this advice has since been updated. In May 2008, EA asked HPA to undertake an assessment of the health risks to people using the beaches along the Cumbrian coast from contaminated objects on the beaches. This report describes the results of that work. The assessment has addressed two key aspects. Firstly, estimates have been made of the likelihood that people using the beaches for various activities could come into contact with a radioactive object. Secondly, in the unlikely event that an individual does come into contact with such an object, the resulting radiation doses and associated health risks have been assessed. The conclusion, based on currently available information, is that the overall health risks for beach users are very low, and significantly lower than other risks that people accept when using the beaches. HPA has updated its formal advice to EA taking into account the findings of this study and the significance of the estimated health risks. HPA recommends three criteria for prompting an urgent review of health risks to beach users. These address risks from ingestion, overall fatal cancer risk and risk of deterministic effects to skin. It also recommends that continued regular monitoring of Sellafield beach and monitoring at one or two other beaches with high public occupancy will provide regulators and the public with continued reassurance that risks associated with radioactive objects in the environment remain very low."
The HPA confirm that the advice provided in 2009, that "no special precautionary actions are required at this time to limit access to or use of beaches" remains valid. The FSA have also confirmed that the risks associated with consumption of seafood "is acceptable".
Regulator and Stakeholder Engagement
Requirements are placed on Sellafield Ltd by the Environment Agency that includes a specification for a programme of works that focuses on radioactive particles in the environment. A programme of works document was produced by the Environment Agency in February 2008. Sellafield Ltd is now responsible for the further development and delivery of the programme. This programme is reviewed on an annual basis and agreed with the Environment Agency.
Communication and consultation between Sellafield Ltd and the Environment Agency is maintained through regular meetings. In addition, Sellafield Ltd has established a Seabed Working Group, with representation from the Environment Agency, Health Protection Agency and Food Standards Agency, with a specific focus on the offshore environment. The Environment Agency also hosts a multi-agency workshop that provides a forum for regulators, agencies and other interested stakeholders to discuss the particles work and to help inform future requirements. On a routine basis, Sellafield Ltd also issues briefing notes to external stakeholders, reporting on the progress being made and on any key issues.
The Committee on Medical Aspects of Radiation in the Environment (COMARE) is an independent expert advisory committee with members chosen for their medical and scientific expertise. The COMARE Sellafield Working Group (SWG) liaises with the Environment Agency and is kept informed of the particles work via routine meetings and through requests for information. Representatives from COMARE have visited Sellafield and observed beach monitoring operations.
Recognising that monitoring local beaches is a task that takes place outside of the site boundary and is visible to members of the public, Sellafield Ltd have been proactive in meeting with local Parish Councils to discuss beach monitoring activities and agree the timing and scheduling of beach visits. Regular updates are also provided to the West Cumbria Sites Stakeholder Group (WCSSG) Environmental Health Sub-Committee.
Beach Monitoring
Monitoring Programme
The large area beach monitoring programme for the current year can be viewed via the attached link (Beach monitoring programme). The programme takes account of the history of find locations (both particles and stones) and the occupancy information for each beach. The programme is reviewed annually and its scope and extent agreed with the Environment Agency. Stakeholder views are also considered during the review process.
Monitoring Equipment
Left: The original Hillcat Monitoring Vehicle used for large scale beach monitoring.
Right: Softtrack Monitoring Vehicle
Since January 2007, large area beach monitoring at Sellafield has utilised a specialist detection system, known as Groundhog™, developed by Nuvia Ltd. The Groundhog™ vehicle based Evolution 2 system has been specifically designed for detection and removal of radioactive particles in beach environments. The detection system has five large volume Sodium Iodide (Thallium activated) (NaI(Tl)) detectors set in a staggered array capable of monitoring over a width of 2 metres.
Starting in August 2009, large area beach monitoring has been undertaken using Nuvia’s latest development in the Groundhog™ system – the Synergy. Designed to further improve detection capability, the difference between the instrument configuration of the Groundhog™ Evolution 2 and Synergy systems is the introduction of 8 FIDLER (Field Instrument for the Detection of Low-Energy Radiation) detectors. The 5 NaI(Tl) and 8 FIDLER detectors are mounted in a carbon fibre box rather than the metal box used for the Evolution 2 system. Each detector is also contained within its own individual carbon fibre case resulting in improvement in NaI(Tl) detector efficiency, mainly at lower gamma energies.
Field trials of Nuvia Ltd’s Groundhog™ systems, using sealed radioactive sources placed in the beach, have been undertaken and have demonstrated that the system is capable of meeting, and often exceeding, the specified monitoring requirements. Practical experience has shown that the Groundhog™ Evolution 2 system is effective at finding mid-to-high gamma energy items buried up to 30 cm and low gamma energy items close to the surface.
Strand line monitoring undertaken on local beaches uses a hand held, thin walled Geiger- Müller (G-M) detector; and also employs the Groundhog™ Synergy vehicle based system for surveys of the most recent (i.e. last tide) strand line. The use of G-M detectors have been successfully employed since 1983 with a practical balance achieved between probe sensitivity and robustness (tests with alternative probes have experienced higher rates of damage).
During beach monitoring operations, the health and safety of the public and the Nuvia operators who are actively seeking and removing radioactive particles, is of paramount importance to Sellafield Ltd. As part of the contract, Nuvia beach monitoring personnel undergo routine medical screening. During 2010, an investigation, carried out by Nuvia, identified that a small number of medical samples had been accidentally contaminated. The Health Protection Agency was invited to review the investigation; and concluded that improvements could be made. As a result of the Nuvia investigation and HPA review a number of changes have been introduced to further minimise risk to Nuvia operators and to avoid inadvertent bioassay sample contamination. No further problems have occurred since. The investigation has also provided further reassurance that beach monitoring is a very low risk activity. Click on the links to view the Executive Summary of the HPA review and a letter to Sellafield Ltd.
Finds and Analysis
Since the beginning of the large area beach monitoring trials, a number of 'finds', categorised into particles (smaller than 2 mm) or stones (larger than 2 mm), have been removed from the beaches, The attached link gives access to a summary of all the beach find data and the areas monitored each year (Beach Monitoring Summary). All particles and stones detected during monitoring are removed from the beach and taken to the site laboratories for analysis and storage.
A sub-set of finds have also been sent for an extensive set of further analysis via a contract with Serco, utilising the services of the National Physical Laboratory. The results from this work are available to view in the reports section below.
Maps
Maps have been provided to help explain the extent of the finds and provide information in an easy to understand way. The attached link (Maps) provides a number of maps showing the data in different ways.
Reports
Sellafield Ltd beach monitoring reports since the start of the trials are available here.
Nuvia Ltd annual monitoring reports, provided to Sellafield Ltd under contract, are available here
Sea-bed Assessment
Sea-bed Working Group
Underwater monitoring for radioactive particles that may be present in a dynamic seabed environment is not straightforward and presents significant operational and technical difficulties. There is no off-the-shelf solution that could be employed underwater to reliably detect and recover the types of material that are being removed from the beaches local to Sellafield. In order to help inform development of an achievable monitoring specification, it is first appropriate to take a risk-based approach to assess and determine the best potential method(s).
Sellafield Ltd has established the Sea-bed Working Group with membership from the Environment Agency, Food Standards Agency and Health Protection Agency, with the aim:
To develop the requirements for information on potential offshore particles, to support the determination of risks to members of the public.
As a first step the group was focussed on developing an appropriate risk assessment that could be used to help inform the basis for particle monitoring / sampling; and specify the required monitoring system performance.
Particle Transport and Dispersion
Sellafield Ltd has been gathering further information to help develop understanding of transport and dispersion of particles in the offshore environment. This has included the 8 month deployment of underwater equipment to measure currents, by The Centre for Environment, Fisheries and Aquaculture Science (Cefas).
Details of this and other work are provided in the Sellafield Ltd reports: Offshore Monitoring at Sellafield: Status and Progress Report – Work Done to March 2010 and the Annual Report for 2010/11 (30Mb)
Sea-bed Monitoring
Typically, any monitoring of the seabed requires the use of specialist contractors and specially designed equipment. Worldwide experience of monitoring the seabed for radioactive particles is extremely limited, with the greatest knowledge being gathered through the work being done at Dounreay. The material recovered from Sellafield beaches, is different to that present at Dounreay, and requires a separate evaluation to determine what type(s) of monitoring may be most appropriate and achievable.
The work being done by the Sea-bed Working Group and offshore data gathering , will help inform the development of a monitoring specification. Sellafield Ltd is continuing to explore and consider possible techniques and technologies that could deliver a seabed monitoring solution. In addition, past records of marine samples, that have been collected over the years (extending back over recent decades), have been reviewed as possible indicators for the presence of radioactive particles, but provide no evidence of widespread particle populations.
