Gaseous discharges: discharge limits and radiation doses

1 January 2000

Gaseous discharges: discharge limits and radiation doses
  Berkeley Berkeley     Hinkley          
Liquid Charges centre station Bradwell DungenessA Point A Oldbury Sizewell A Trawsfynydd Wylfa Total
Tritium                    
Existing limit (TBq/year) 2.0 1.5 3.0 25 5.0 7.0 10 20 73.5  
Limit in draft authorisation (TBq/year) 0.05 0.025 1.5 2.6 5.0 9.0 3.5 0.75 18 40.4
Critical group dose at draft authorisation                    
limit (microSv/year) 0.028 0.0071 0.26 0.14 0.48 1.2 0.51 0.066 1.0 n/a
Carbon-14                    
Existing limit (TBq/year) 0.2 0.6 5.0 4.0 6.0 1.5 5.0 2.4 24.7  
Limit in draft authorisation (TBq/year) 0.001 0.0005 0.6 5.0 4.0 5.0 2.0 0.01 2.3 18.9
Critical group dose at darft authorisation                    
(microSv/year) 0.073 0.024 14 12 50 86 38 0.15 17 n/a
Sulphur-35                    
Existing limit (TBq/year) 0.006 0.20 0.40 0.20 0.75 0.60 0.40 0.50 3.06  
Limit in draft authorisation (TBq/year) No limit No limit 0.19 0.15 0.17 0.45 0.35 No limit 0.45 1.76
Critical group dose at draft authorisation llimit                    
(microSv/year) n/a n/a 51 0.59 26 96 82 n/a 45 n/a
Argon-41                    
Existing limit (TBq/year) No limit No limit 1000 2000 4500 500 3000 3500 120 14,620
Limit in draft authorisation (TBq/year) No limit No limit 1000 1700 4000 500 3000 No limit 100 10,300
Critical group dose at draft authorisation limit                    
(microSv/year) n/a n/a 15 152 40 7.6 53 n/a 0.71 n/a
Beta particulate                    
Existing limit (Tq/year) 0.00002 0.0002 0.001 0.001 0.001 0.001 0.001 0.002 0.001 0.00822
Limit in draft authorisation (TBq/year) 0.00001 0.00002 0.00075 0.00055 0.0004 0.0001 0.00085 0.00005 0.001 0.00373
Critical group dose at draft authorisation limit                    
(microSv/year) 0.0073 0.017 0.18 0.36 0.055 0.019 0.18 0.0084 0.089 n/a
Total dose to critical group from gaseous discharges                    
(microSv/year) 0.11 0.048 80 165 116 191 174 0.22 64 n/a
1. At Berkeley centre, a draft limit of 100GBq/year is placed on gaseous discharges of Krypton-85. This would result in a critical group dose of 0.00011microSv/year.
2. The critical group doses for Berkeley Centre and Berkeley Station are subject to amendment following receipt of an application document from BNFL. After recalculation, the combined contribution to the critical group dose will remain small and will not exceed 1microSv/year



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