Appendix CRF - Part 3 - Northamptonshire County Council

Radiological Assessment 0820-2
Version 2
Parameter Description Value Units
W width of the source perpendicular to
the wind direction
10 m
u mean wind speed 6.2 m s –1
h height for vertical mixing 2.0 m
Oout time spent in the worker 880
hours year
gas plume public 2192
–1
B breathing rate worker 1.2
m
public 1.0
3 hour -1
K1 effective dose equivalent
corresponding to an absorbed energy
of 1 joule
2.0 Sv J -1
equilibrium factor 0.8 dimensionless
K2 potential -energy of Rn-222 in
equilibrium with its daughters
5.5x10 -9
J Bq -1
Table A.1 Parameter values used in calculations of doses through the gas pathway
during site operations.
A.2 Doses to site residents after closure
For calculation of peak dose, it is assumed that a house is constructed on top of the
landfill cap immediately after closure. Irradiation doses are calculated for a resident
spending 75% of the time indoors and 25% outdoors. Doses from gas inhalation are
calculated for indoor exposure of the house resident to gas accumulating in the
dwelling.
where: Oout
Dose
irr
D
Rn
irr , slab
Rn
Rn,
waste
x(
t )
OOsf
e
out
in
A
V
Galson Sciences Limited 68 14 July 2009
waste
( t )
waste
is the time spent outside exposed to the waste (years year –1 ).
Oin is the time spent inside (years year –1 ).
sf is the shielding factor from the ground when indoors (dimensionless).
ARn, waste(t) is the activity of the radionuclide, Rn (Bq), in the waste at time t
Dirr,slab The dose conversion factor for irradiation from radionuclide Rn (Sv
year -1 Bq -1 kg), based on the receptor being 1 m from the ground and
the contamination being spread out so as to approximate a semiinfinite
slab.
Vwaste is the volume of material in which radioactivity is present (m 3 ).
waste is the bulk density of the waste (kg m -3 ).
Rn is the attenuation coefficient for radionuclide Rn (m -1 ).
x is the thickness of the cap (m).
Doses from inhalation of radioactive gases (excluding radon) are calculated from:
Dose
gas,
indoors
D
Rn
inh
B
O
in
R
where: B is the breathing rate (m 3 year -1 ).
Rn,
gas
a
H 1
( t)
a kV
WS010001/ENRMF/CONSAPPCRF 618