Dounreay Particles Advisory Group
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Dounreay Particles Advisory Group Third Report September 2006 Dounreay Particle Advisory Group Third Report Publishing Organisation Scottish Environment Protection Agency, Erskine Court, Castle Business Park, Stirling, FK9 4TR Tel: 01786 457700 Fax: 01786 446885 Website: www.sepa.org.uk © SEPA 2006 ISBN: 1-901322-64-5 i ii FOREWORD The Group was faced with the dilemma of producing this Third Report promptly with major gaps in our knowledge, which we had identified, or awaiting provision of the most vital information. We chose the latter option. It was decided that, with a single exception, information received after the end of February could not be considered adequately for inclusion in this Report. As the exception, the Group considered it essential to confirm in practice our theoretical assessment of the performance of Groundhog Evolution (and its predecessor) in monitoring of beaches for particles. Under the auspices of COMARE, we participated in empirical measurements undertaken at Sandside Bay in April 2006, which was the earliest opportunity circumstances permitted. The Group had also considered it essential to monitor the beach at Dunnet Bay. A major review of the potential consequences for health of particles was proposed by the Group, commissioned by SEPA and undertaken comprehensively by the Radiation Protection Division of the Health Protection Agency. We have now been able to set our findings in the context of public health, which we regard as the most important factor, and to categorise particles as Significant, Relevant or Minor according to their potential to cause harm. Information was sought on the relationship between the activity of particles and their mass and density in order to understand better their behaviour in the marine environment. Data relating activity and mass were provided recently but problems remain in establishing reliable measurements of density. Further information was also sought on the distribution of particles in the marine environment and on the Dounreay Foreshore and local beaches. Unfortunately, for a variety of reasons, delays in producing these data were frustratingly greater than we had anticipated and beyond our control. Post deadline, UKAEA disclosed information on the nature of particles and their classification that was so fundamental it was necessary to make late reference to it and include corrections to data provided previously. Constructively, relevant reports potentially helpful to our understanding have also been provided but too late for their implications to be evaluated by the Group and included in this Report. If the Group is tasked with further consideration of current research conducted by UKAEA, these reports that have now been made available and any others will be addressed in a Fourth Report. However, although substantial uncertainties remain, we consider that the Report is now as comprehensive as our current knowledge permits, unifying our improved understanding of the diverse aspects of particles in the environment around Dounreay. It is intended to provide a sound basis on which judgements of future action and the need for further research can be made. As Chairman of DPAG, I wish to record my deep gratitude to the members of the Group for their unstinting dedication and support despite the many competing demands on their professional time. Their collective multidisciplinary expertise was vital in achieving our present overall understanding and production of this Report. We are greatly indebted to our excellent Technical Secretary, Dr. Paul Dale. Despite other major commitments within SEPA, he has served us tirelessly with great enthusiasm and energy as well as providing counsel that is wise beyond his years. Allyson Wilson consistently demonstrated outstanding organisational and administrative skills on our behalf and latterly was ably supported by June Moore. Prior to his appointment as Chief Executive of SEPA, Dr. Campbell Gemmell chaired the iii Group with typical commitment, vision and enthusiasm. The Group unanimously accorded him the title of Honorary Member and is grateful for his continued close interest and support. We are grateful for the helpful contributions of our Observers and to UKAEA, Dounreay, for providing information we sought via SEPA. Professor Keith Boddy CBE, DSc, FRSE. Chairman of DPAG iv FOREWORD iii ACRONYMS AND ABBREVIATIONS ix EXECUTIVE SUMMARY xiii BACKGROUND TO THE ESTABLISHMENT OF DPAG xix 1. INTRODUCTION 1 1.1 Background 1 1.2 Scope of Work Undertaken by DPAG 1 1.3 Previous Interim Reports 2 1.4 Recommendations from Previous Reports 3 1.5 The Present Report 4 2. NATURE, ORIGINS AND ROUTES OF RELEASE OF PARTICLES TO THE ENVIRONMENT FROM UKAEA DOUNREAY 6 2.1 Nature 6 2.2 Generation of particles 9 2.3 Routes of Release of Particles to the Environment 11 2.4 Summary 20 3. HEALTH EFFECTS 24 3.1 Potential Doses and Risks from Fuel Particles 24 3.2 Dose Assessment Methodology 27 4. OFFSHORE PARTICLES 34 4.1 Introduction 34 4.2 Classification and Characteristics of the Offshore Particles 36 4.3 The Distribution of Particles on the Sea Bed and Estimation of Total Numbers Present 51 4.4 Offshore Particles – Patterns and Interpretation 61 4.5 Assessment of the Wallingford Model 80 4.6 Conclusions and Implications 85 5. BEACH MONITORING 90 5.1 Introduction 90 5.2 A review of the capabilities of Groundhog Mk 1 102 5.3 A review of the capabilities of Groundhog Evolution 105 5.4 Empirical validation 109 5.5 Lessons from particles found (Sandside Beach and Dounreay Foreshore) 117 5.6 Reconstruction of Particle Abundance at Sandside Bay 119 5.7 Summary and conclusions 122 5.8 Recommendations 125 v 6. IMPLICATIONS FOR HEALTH AND PROCEDURES 128 6.1 Principles of Radiological Protection 128 6.2 Fuel Particles of Radiological Relevance 128 6.3 The Potential for Radiologically Significant Fuel Particles to be Deposited 129 6.4 The Probability of Coming into Contact with a Fuel Particle at Sandside Bay 130 6.5 Performance Criteria for the Detection System 132 6.6 The Extent and Frequency of Monitoring 132 6.7 Assessment of the Current Programme and Equipment 133 6.8 Monitoring after Storms 134 6.9 Potential Future Actions at Sandside Bay 135 7. OVERVIEW, CONCLUSIONS AND RECOMMENDATIONS 140 7.1 Background 140 7.2 Nature of Particles 140 7.3 Occurrence of Particles in the Environment 141 7.4 The Marine Environment 142 7.5 Monitoring of the Littoral Environment 143 7.6 Health Implications 144 7.7 Intervention: Remediation and Amelioration 146 7.8 Recommendations 147 7.9 Identification of further work 149 REFERENCES 150 GLOSSARY OF TERMS AND DEFINITIONS USED 154 APPENDIX A DPAG MEMBERSHIP 164 APPENDIX B BIOGRAPHICAL DETAILS OF CURRENT MEMBERS 166 APPENDIX C RECOMMENDATIONS FROM DPAG’S SECOND INTERIM REPORT 170 APPENDIX D CHRONOLOGY OF HISTORICAL PRACTICES AND EVENTS, AT UKAEA DOUNREAY 174 APPENDIX E COULD THE DOUNREAY SHAFT BE A POSSIBLE SOURCE FOR THE MARINE PARTICLES? 180 APPENDIX F THE PROBABILITY OF ENCOUNTERING A FUEL PARTICLE WHILE ON THE BEACH AT SANDSIDE BAY 196 APPENDIX G ANALYSIS OF LOG(10) ACTIVITY AND MASS FOR THE PARTICLE FINDS 214 APPENDIX H SUPPORTING INFORMATION FOR CHAPTER 5 220 APPENDIX I ALL PARTICLES DETECTED AND RECOVERED TO END OF FEBRUARY 2006 233 vi vii 13799_vi.indd 1 29/8/06 12:35:30 pm viii ACRONYMS AND ABBREVIATIONS AEA Atomic Energy Authority Al Aluminium 241Am Americium-241 137mBa Metastable Barium-137 bar 1 atmosphere pressure BPEO Best Practicable Environmental Option BMSG Beach Monitoring Steering Group BMM Beach Monitoring Modelling Bq Bequerel CERRIE Committee Examining Radiation Risks from Internal Emitters COMARE Committee on Medical Aspects of Radiation in the Environment 60Co Cobalt-60 137Cs Caesium-137 DFR Dounreay Fast Reactor DGPS Differential Global Positioning System DMTR Dounreay Materials Test Reactor DPAG Dounreay Particles Advisory Group DSRP Dounreay Site Restoration Plan ED50 Dose EDAX Energy Dispersive X-ray Analysis EPS Electronic Positioning System et al. And others FCA Fuel Cycle Area FEPA Food and Environment Protection Act (1985) FITS Fathom Instrument Towed System g gramme g cm-3 grammes per cubic centimetre GBq Gigabequerel GPS Global Positioning System Gy Gray h hour(s) ha hectare(s) HAP High Activity Population HAT Human Alimentary Tract HATM Human Alimentary Tract Model ix HEPA High Efficiency Particulate in Air HPA-RPD Health Protection Agency - Radiation Protection Division HR Hydraulics Research HSE Health and Safety Executive ICRP The International Commission on Radiological Protection ICRU International Commission on Radiological Units and Measurements IAEA International Atomic Energy Agency ILW Intermediate Level Waste LAD Low Active Drain LLI Lower Large Intestine LWMOT Low Water Mean Ordinary Tide LWN Low Water Neap tides MBq Megabequerel mGy milligray MHWS Mean High Water Spring tides MLWS Mean Low Water Spring tides m s-1 Metres per second mSv Milli-sievert MTR Materials Test Reactor NaI Sodium Iodide 93Nb Niobium-93 94Nb Niobium-94 NNC National Nuclear Corporation NRPB National Radiological Protection Board NSPAD Near Surface Particle Activity Distribution O Oxygen OD Ordnance Datum 238Pu Plutonium-238 PFR Prototype Fast Reactor PTFE Polytetrafluoroethylene 106Ru Ruthenium-106 RWMAC Radioactive Waste Management Advisory Committee 90Sr Strontium-90 SE (The) Scottish Executive SEM Scanning Electron Microscope SEPA Scottish Environment Protection Agency SHIP Shaft Isolation Programme x SS Stainless Steel SUERC Scottish Universities Environmental Research Centre SURRC Scottish Universities