Difference between revisions of "Keyword:DOSE"
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< -- Inventory phase -- > | < -- Inventory phase -- > | ||
... | ... | ||
| + | |||
| + | Note that the specific activity (Bq/kg), not the activity (Bq), is used to calculate dose rates, in both cases. | ||
| + | |||
| + | The surface gamma dose rate (Sv/hr), <math>D</math> for a semi-infinite slab is calculated as below: | ||
| + | |||
| + | <math> | ||
| + | D=C \frac{B}{2} \sum_{i=1}^{N_{\gamma}} \frac{\mu_{a}\left(E_{i}\right)}{\mu_{m}\left(E_{i}\right)} S_{\gamma}(E_{i}) | ||
| + | </math> | ||
| + | |||
| + | where: | ||
| + | |||
| + | <math>N_{\gamma}</math> = number of energy groups in the <math>\gamma</math> spectrum histogram | ||
| + | |||
| + | <math>E_{i}</math> = mean energy of the <math>i^{th}</math> energy group | ||
| + | |||
| + | <math>\mu_{a}</math> = mass energy absorption coefficient (<math>\mu_{en}/\rho</math>) of air (m<math>^{2}</math> kg<math>^{−1}</math>) | ||
| + | |||
| + | <math>\mu_{m}</math> = mass energy attenuation coefficient (<math>\mu/\rho</math>) of the material (m<math>^{2}</math> kg<math>^{−1}</math>) | ||
| + | |||
| + | <math>B</math> = build up factor (= 2) | ||
| + | |||
| + | <math>S_{\gamma}</math> = rate of <math>\gamma</math> emission (MeV kg<math>^{−1}</math> s<math>^{−1}</math>) | ||
| + | |||
| + | <math>C</math> = 3.6 <math>\times</math> 10<math>^{9}|e|</math> converts (MeV kg<math>^{−1}</math> s<math>^{−1}</math>) to (Sv/hr) | ||
| + | |||
| + | |||
| + | Whereas the dose rate (Sv/hr) from a point source in air, <math>D</math>, is calculated as below: | ||
| + | |||
| + | <math> | ||
| + | D=C \sum_{i=1}^{N_{\gamma}} \frac{\mu_{a}}{4 \pi r^{2}} e^{-\mu\left(E_{i}\right) r} m_{s} S_{\gamma}(E_{i}) | ||
| + | </math> | ||
| + | |||
| + | where additional terms are defined as: | ||
| + | |||
| + | <math>m_{s}</math> = mass of source (kg) | ||
| + | |||
| + | <math>r</math>= distance from source (m) | ||
| + | |||
| + | <math>\mu(E_{i})</math> = energy attenuation coefficient of air (m<math>^{−1}</math>) | ||
| + | |||
| + | In both cases the emission rate, <math>S_{\gamma}</math>, is calculated using the specific activity, <math>A(t)</math> (Bq/kg), as below: | ||
| + | |||
| + | <math> | ||
| + | S_{\gamma}(E_{i}) = I_{i}A(t) | ||
| + | </math> | ||
| + | |||
| + | where <math>I_{i}</math> is the intensity of energy group <math>i</math> (MeV). | ||
Revision as of 07:50, 25 April 2019
DOSE ndose {1} <dist> {0}
Dose rates are calculated for a semi-infinite slab of the material. This is the default if the keyword is not used or if ndose = 1, but if ndose = 2 then the calculations are done for a point source of 1 g of material at a distance of dist metres. dist is not used for the semi-infinite slab as the contact dose rate is always assumed. The minimum distance is 0.3 m; if a smaller value is specified then dist is set to 0.3 m and a message to this effect is printed.
An example of this keyword for a point source of 1 gram of the irradiated material at 1 metre is:
< -- Control phase -- > ... FISPACT * Title of the simulation < -- Initial phase -- > ... DOSE 2 1.0 ... < -- Inventory phase -- > ...
Note that the specific activity (Bq/kg), not the activity (Bq), is used to calculate dose rates, in both cases.
The surface gamma dose rate (Sv/hr), [math]D[/math] for a semi-infinite slab is calculated as below:
[math] D=C \frac{B}{2} \sum_{i=1}^{N_{\gamma}} \frac{\mu_{a}\left(E_{i}\right)}{\mu_{m}\left(E_{i}\right)} S_{\gamma}(E_{i}) [/math]
where:
[math]N_{\gamma}[/math] = number of energy groups in the [math]\gamma[/math] spectrum histogram
[math]E_{i}[/math] = mean energy of the [math]i^{th}[/math] energy group
[math]\mu_{a}[/math] = mass energy absorption coefficient ([math]\mu_{en}/\rho[/math]) of air (m[math]^{2}[/math] kg[math]^{−1}[/math])
[math]\mu_{m}[/math] = mass energy attenuation coefficient ([math]\mu/\rho[/math]) of the material (m[math]^{2}[/math] kg[math]^{−1}[/math])
[math]B[/math] = build up factor (= 2)
[math]S_{\gamma}[/math] = rate of [math]\gamma[/math] emission (MeV kg[math]^{−1}[/math] s[math]^{−1}[/math])
[math]C[/math] = 3.6 [math]\times[/math] 10[math]^{9}|e|[/math] converts (MeV kg[math]^{−1}[/math] s[math]^{−1}[/math]) to (Sv/hr)
Whereas the dose rate (Sv/hr) from a point source in air, [math]D[/math], is calculated as below:
[math] D=C \sum_{i=1}^{N_{\gamma}} \frac{\mu_{a}}{4 \pi r^{2}} e^{-\mu\left(E_{i}\right) r} m_{s} S_{\gamma}(E_{i}) [/math]
where additional terms are defined as:
[math]m_{s}[/math] = mass of source (kg)
[math]r[/math]= distance from source (m)
[math]\mu(E_{i})[/math] = energy attenuation coefficient of air (m[math]^{−1}[/math])
In both cases the emission rate, [math]S_{\gamma}[/math], is calculated using the specific activity, [math]A(t)[/math] (Bq/kg), as below:
[math] S_{\gamma}(E_{i}) = I_{i}A(t) [/math]
where [math]I_{i}[/math] is the intensity of energy group [math]i[/math] (MeV).
