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

2. 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: te te te, te
Magnox: te te te, te
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3. 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
I-129 dropped by 50% from 2016.

4. 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 ( ) 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.
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5. 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 year average habit data and SL monitoring data (excludes aerial pathways).
Data from SLNSC Paper No
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6. 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.
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7. 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
Decrease between 2016 and 2017: - Kr-85, Sb-125, I-129, Cs-137
Increase between 2016 and 2017:- Pu-alpha, Pu-241
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8. 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.
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9. 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 data.
Taken from Quarter Statutory Environmental Monitoring report.
Calculated from 2016 and 2017 monitoring data.
Total dose for 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
Taken from Sellafield Ltd Annual report on 2016 data.
Taken from Quarter 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.

10. 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
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11. Future discharges- Alpha
UKDST does not have legally binding limits.
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12. Future discharges- Beta
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