Sellafield Discharges and Environmental Monitoring 2017 A Preliminary Assessment P McDonald Date: 7th June 2018 Final assessment will be presented in November meeting.

Liquid Discharges 2017 2017 liquid discharges were well within permitted limits. The highest discharges as a proportion of the limit was Pu-alpha at 21% of the limit. Overall, discharges lower than previous year, reflecting the reduction in reprocessing throughput. Reprocessing rates: Thorp: 2014- 411 te 2015- 399 te 2016-531 te, 2017-292 te Magnox: 2014- 427 te 2015- 428 te 2016-476 te, 2017-339 te EHS&Q Environmental Management

Marine pipeline liquid discharges 2017 Radionuclide Limit 2016 2017   Discharge GBq As % of limit H-3 1.80E+07 2.05E+06 1.30E+06 7% C-14 2.10E+04 4.83E+03 3.60E+03 17% Co-60 3.53E+01 2.12E+01 1% Sr-90 4.50E+04 2.01E+03 2.12E+03 5% Zr/Nb-95 2.80E+03 9.43E+01 6.36E+01 2% Tc-99 1.00E+04 1.90E+03 1.57E+03 16% Ru-106 5.10E+04 1.09E+03 1.03E+03 I-129 2.00E+03 5.22E+02 2.59E+02 13% Cs-134 1.60E+03 6.56E+01 4.24E+01 3% Cs-137 3.40E+04 3.72E+03 3.31E+03 10% Ce-144 4.00E+03 2.13E+02 1.24E+02 Np-237 7.30E+02 3.14E+01 3.63E+01 Pu-Alpha 7.00E+02 1.79E+02 1.50E+02 21% Pu-241 2.50E+04 2.99E+03 2.09E+03 8% Am-241 3.00E+02 2.58E+01 2.02E+01 Cm-Alpha 5.00E+01 2.96E+00 1.92E+00 4% Alpha 9.00E+02 2.53E+02 1.84E+02 20% Beta 1.80E+05 1.31E+04 1.21E+04 Uranium (kg) 2000 342 348 Marine pipeline discharges presented. Also minor discharges from the Factory Sewer. Data from SLNSC Paper No. 2018.22. I-129 dropped by 50% from 2016.

Liquid Critical Group Doses 2017 – measured The adult age group corresponds to the critical group. The provisional total measured dose has decreased slightly in 2017 to 100 Sv from 105 Sv in 2016. 241Am and Pu-Alpha are still the most significant contributors to dose (24 and 12 Sv of the total dose), although the measured concentrations of these nuclides are mostly due to historic rather than 2017 discharges. The measured doses have been assessed by using the five year average (2013-2017) of habit surveys reported by Cefas/ Food Standards Agency (FSA). The total predicted dose received by the critical group from Sellafield liquid discharges in 2017 was 18 Sv, similar to that in 2016 (22 Sv). Dose is largely from shellfish (winkles and mussels) and transuranics, therefore adults rather than infants or children receive highest dose. Small decrease in Pu-alpha and Am-241 concentrations in molluscs in 2017 balanced by small increase in consumption rates. EHS&Q Environmental Management

Liquid Critical Group Doses 2017 – measured Radionuclide Dose in 2016 Dose in 2017   µSv (1) µSv (2) C-14 4.0 6.2 Co-60 0.04 0.03 Sr-90 0.58 0.27 Tc-99 1.8 2.0 Ru-106 0.54 0.63 Sb-125 0.007 0.006 I-129 0.96 1.89 Cs-137 2.9 3.9 Np-237 0.01 Pu-Alpha 15 13 Pu-241 1.1 0.8 Am-241 29 24 Cm-Alpha 0.15 0.06 External 49 48 Total dose 105 100 Taken from Sellafield Ltd Annual report on 2016 data. Calculated from 2013 - 2017 5 year average habit data and SL monitoring data (excludes aerial pathways). Data from SLNSC Paper No. 2018.22 EHS&Q Environmental Management

Aerial Discharges 2017 2017 aerial discharges were well within permitted limits. The highest discharge as a proportion of the limit was Pu-alpha at 18% of the limit. Sb-125 discharges now only 6% of the discharge limit whereas in recent years it was between 35 to 40% of the limit. EHS&Q Environmental Management

Aerial Discharges 2017 EHS&Q Environmental Management Radionuclide Limit 2016 2017   Discharge MBq as % of limit H-3 1.10E+09 1.23E+08 9.94E+07 9% C-14 3.30E+06 4.42E+05 4.16E+05 13% Kr-85 4.40E+11 8.75E+10 4.33E+10 10% Sr-90 7.10E+02 2.95E+01 3.10E+01 4% Ru-106 2.30E+04 7.02E+02 6.51E+02 3% Sb-125 3.00E+04 1.01E+04 1.71E+03 6% I-129 7.00E+04 1.30E+04 6.52E+03 I-131 3.70E+04 4.23E+02 3.74E+02 1% Cs-137 5.80E+03 1.02E+02 4.16E+01 Rn-222 5.00E+05 4.26E+04 3.91E+04 8% Pu-Alpha 1.90E+02 1.54E+01 3.47E+01 18% Pu-241 3.00E+03 1.47E+02 3.32E+02 11% Am-241/Cm-242 1.20E+02 1.36E+01 1.70E+01 14% Alpha(1) 8.80E+02 1.08E+02 1.11E+02 Beta(1) 4.20E+04 1.24E+03 7.85E+02 2% Alpha and Beta values include Open Fuel Storage Ponds & Other Approved Outlets (OFSP&OO) contributions. Data from SLNSC Paper No. 2018.22. Decrease between 2016 and 2017: - Kr-85, Sb-125, I-129, Cs-137 Increase between 2016 and 2017:- Pu-alpha, Pu-241 EHS&Q Environmental Management

Aerial Critical Group Doses 2017 – measured The adult age group corresponds to the critical group. Total measured dose has decreased in 2017 to 9.8 Sv from 15.6 Sv in 2016. The estimate for 2016 excluding FSA data was 11.7 Sv. The largest radionuclide contribution was from Pu-alpha at 0.29 Sv. The measured doses have been assessed by using national habit survey consumption rates as recommended by Public Health England (PHE). The total predicted dose received by the critical group from Sellafield aerial discharges in 2017 is 2.5 Sv compared with 4.7 Sv in 2016. Pu-alpha contribution from air (HVAS). FSA terrestrial data for 2017 will be used to complete the measured dose calculations. The completed data, which will include minor radionuclides and exposure pathways <1 Sv, will be available in October 2018. EHS&Q Environmental Management

Aerial Critical Group Doses 2017 – measured Radionuclide Final measured dose in 2016 Initial measured dose in 2017   µSv (1) µSv (2) H-3 0.14 0.01 C-14 0.59 0.08 Co-60 Kr-85 (3) 0.40 0.17 Sr-90 0.84 0.20 Tc-99 Ru-106 0.03 0.002 Sb-125 0.07 I-129 1.10 0.11 I-131 0.001 0.005 Cs-134 0.37 0.0003 Cs-137 0.96 Pu-Alpha 0.53 0.29 Pu-241 0.58 0.23 Am-241/Cm-242 0.24 Total 6.3 1.6(4) Direct Shine 5.4 4.4 Beach External 2.8 Marine Foods 1.1 Overall Total 15.6 9.8 Taken from Sellafield Ltd Annual report on 2016 data. Taken from Quarter 4 2017 Statutory Environmental Monitoring report. Calculated from 2016 and 2017 monitoring data. Total dose for 2017 is based on Sellafield Ltd monitoring data only. FSA terrestrial data for 2017 will be used to complete the measured dose calculations. The completed data, which will include minor radionuclides and exposure pathways <1 Sv, will be available in October 2018. Data from SLNSC Paper No. 2018.22. Taken from Sellafield Ltd Annual report on 2016 data. Taken from Quarter 4 2017 Statutory Environmental Monitoring report. Calculated from 2016 and 2017 monitoring data. Total dose for 2017 is based on Sellafield Ltd monitoring data only. FSA terrestrial data for 2017 will be used to complete the measured dose calculations. The completed data, which will include minor radionuclides and exposure pathways <1 Sv, will be available in October 2018.

Summary All liquid and aerial discharges well within permitted levels. Impact of 2017 discharges in terms of doses to critical groups are very low compared to the dose constraint of 1000 mSv for exposure to man-made controlled sources of radiation and 500 mSv as a ‘site constraint’ for members of the general public: Aerial – 2.5 mSv Marine – 18 mSv Impact of historic discharges is also significantly below the recommended maximum levels: Marine – 100 mSv EHS&Q Environmental Management

Future discharges- Alpha UKDST does not have legally binding limits. EHS&Q Environmental Management

Future discharges- Beta EHS&Q Environmental Management