Radiological Habits Survey: Dounreay, 2013 This page has been intentionally left blank Environment Report RL 06/14 Final report Radiological Habits Survey: Dounreay, 2013 G.P. Papworth, C.J. Garrod and F.J. Clyne Peer reviewed by G.J. Hunt Approved for publication by W.C. Camplin 2014 The work described in this report was carried out under contract to the Scottish Environment Protection Agency SEPA contract R90077PUR Cefas contract C3745 This report should be cited as: Papworth, G.P., Garrod, C.J. and Clyne, F.J., 2014. Radiological Habits Survey: Dounreay 2013. RL 06/14. Cefas, Lowestoft A copy can be obtained by downloading from the SEPA website: www.sepa.org.uk and from the Cefas website: www.cefas.defra.gov.uk © Crown copyright, 2014 Page 2 of 62 Radiological Habits Survey: Dounreay, 2013 CONTENTS SUMMARY .............................................................................................................................................. 7 1 INTRODUCTION ........................................................................................................................... 13 1.1 Regulation of radioactive waste discharges .......................................................................... 13 1.2 The representative person .................................................................................................... 13 1.3 Dose limits and constraints ................................................................................................... 13 2 THE SURVEY ............................................................................................................................... 15 2.1 Site activity ............................................................................................................................ 15 2.2 Survey aims ........................................................................................................................... 15 2.3 Survey areas ......................................................................................................................... 16 Figure 1. The Dounreay aquatic survey area ............................................................................... 17 Figure 2. The Dounreay terrestrial (outer ring) and direct radiation (inner ring) survey areas ..... 18 2.4 Conduct of the survey ........................................................................................................... 19 3 METHODS FOR DATA ANALYSIS ............................................................................................. 20 3.1 Data recording and presentation ........................................................................................... 20 3.2 Data conversion .................................................................................................................... 20 3.3 Rounding and grouping of data ............................................................................................. 20 3.4 Approaches for the identification of high rates ...................................................................... 21 3.5 Infant and child ratios for use in dose assessments ............................................................. 22 4 AQUATIC RADIATION PATHWAYS ........................................................................................... 23 4.1 Aquatic survey area .............................................................................................................. 23 Figure 3. Port a’ Chinn .................................................................................................................. 24 Figure 4. Port Skerra .................................................................................................................... 25 Figure 5. Melvich Bay ................................................................................................................... 25 Figure 6. Sandside Bay ................................................................................................................ 26 Figure 7. Scrabster beach ............................................................................................................ 28 Figure 8. Thurso beach ................................................................................................................. 29 Figure 9. Bait digging beach at Castletown .................................................................................. 30 Figure 10. Dunnet beach .............................................................................................................. 30 4.2 Commercial fisheries ............................................................................................................. 31 4.3 Destination of seafood originating from the aquatic survey area .......................................... 32 4.4 Angling and hobby fishing ..................................................................................................... 32 4.5 Other pathways ..................................................................................................................... 33 4.6 Specific activities investigated at the request of SEPA ......................................................... 33 Table A. Estimates of the relative proportion of the commercial fishery catches taken from the 2 km - 10 km zone and the 10 km - 20 km zone .................................................................... 34 4.7 Internal exposure .................................................................................................................. 35 Table B. Summary of adults’ consumption rates of foods from the aquatic survey area ............. 35 Table C. Summary of children’s and infants’ consumption rates of foods from the aquatic survey area .................................................................................................................................... 36 4.8 External exposure ................................................................................................................. 37 Table D. Summary of adults’ intertidal occupancy rates .............................................................. 37 Table E. Summary of children’s and infants’ intertidal occupancy rates ...................................... 38 Table F. Summary of adults’ handling rates of fishing gear and sediment................................... 39 Table G. Summary of children’s handling rates of sediment ........................................................ 39 5 TERRESTRIAL RADIATION PATHWAYS .................................................................................. 41 5.1 Terrestrial survey area .......................................................................................................... 41 5.2 Land cover ............................................................................................................................. 42 Figure 11. Land cover in the Dounreay area ................................................................................ 43 5.3 Internal exposure .................................................................................................................. 44 Table H. Summary of adults’ consumption rates of foods from the terrestrial survey area .......... 44 Page 3 of 62 CONTENTS Table I. Summary of children’s and infants’ consumption rates of foods from the terrestrial survey area .................................................................................................................................... 46 6 DIRECT RADIATION PATHWAYS .............................................................................................. 47 6.1 Direct radiation survey area .................................................................................................. 47 6.2 Occupancy rates and gamma dose rate measurements ...................................................... 47 Table J. Summary of direct radiation occupancy rates ................................................................. 47 7 USES OF HABITS DATA FOR DOSE ASSESSMENTS ............................................................. 49 8 COMPARISONS WITH THE PREVIOUS SURVEY ..................................................................... 50 Table K. Comparison between 2008 and 2013 consumption rates of aquatic food groups for adults ............................................................................................................................................. 50 Table L. Comparison between 2008 and 2013 intertidal occupancy rates and handling rates of fishing gear and sediment for adults .......................................................................................... 51 Table M. Comparison between 2008 and 2013 mean consumption rates for the adult high-rate groups for terrestrial food groups (kg y-1 or l y-1) ........................................................................... 52 Table N. Comparison between 2008 and 2013 highest direct radiation occupancy rates (h y-1) ..................................................................................................................................... 53 9 MAIN FINDINGS ........................................................................................................................... 54 10 SUGGESTIONS FOR CHANGES TO THE MONITORING PROGRAMME ................................ 57 10.1 Summary of the current environmental monitoring programme ........................................... 57 10.2 Suggestions for changes ......................................................................................................