Appendix CRF - Part 3 - Northamptonshire County Council

Radiological Assessment 0820-2
Version 2
Appendix A Dose calculations
A.1 Doses during site operations
The air concentration of a radionuclide, CRn,gas,outdoors (Bq m -3 ), can be approximated
by dividing by the air volume into which the activity released per year is diluted:
C
Rn , gas,
outdoors
Rn,
gas
Wuh3.16E 07
where: RRn,gas is the release rate of radionuclide Rn in gas (Bq year –1 ) at the time of
interest.
W is the width of the source perpendicular to the wind direction (m).
u is the mean wind speed (m s –1 ).
h is the height for vertical mixing (m).
3.16E+07 is the number of seconds in a year (s year –1 ).
The dose from gases other than radon is given by:
Dose B O
D
gas,
outdoors
Galson Sciences Limited 67 14 July 2009
R
CRn,
gas,
outdoors
where: Oout
is the time spent in the gas plume (years year –1 ).
B is the breathing rate (m 3 year -1 ).
Dinh is the dose coefficient for inhalation of radionuclide Rn (Sv Bq -1 ).
The dose calculation for radon must account for the effect of the daughters of Rn-222
in the body, and has several additional terms:
where: K1
Doseradon, outdoors Cradon,
outdoors K1
B Oout
out
Rn
inh
K
is the effective dose equivalent corresponding to an absorbed energy
of 1 joule (Sv J -1 ).
is the equilibrium factor (dimensionless).
K2 is the potential -energy of Rn-222 in equilibrium with its daughters
(J Bq -1 ).
Radionuclide-specific data are presented in Appendix 2. Other parameter values used
in the calculation of specific doses for the ENRMF site are presented in Table A.1.
WS010001/ENRMF/CONSAPPCRF 617
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