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10. Natural Uranium separation
From radiation protection point of view, it makes sense to distinguish between the isotopes of the
natural U-238 decay chain (U
much lower than for Plutonium while the natural Thorium decay chain includes nuclides with dose
coefficients similar to Plutonium. In many mines and Uranium facilities, U
LLRD activity.
The separation algorithm uses the circumstance that the maximum emission energy of the whole U
decay chain is about 4.7MeV. All nuclides or decay chains with higher dose coefficients emit their
alpha particles with energies above 4.7MeV. That means, if some LLRD activity appears in the energy
region above 4.7MeV, we can assume that nuclides with high dose coefficients are present. In this
case, the Plutonium dose coefficient will be applied to calculate the dose from the measured
exposure - otherwise the instrument applies the one for U
covers the whole LLRD activity even if a mixture of U
implementation may result in a dose overestimation for such situations.
The configuration of the instrument allows the definition of two separate dose coefficients for U
and Plutonium. If a user knows that only U
operation, both coefficients could be set either for U
If the instrument applies the U
alpha dose value is shown). Please note: Due to statistical deviations and Radon background
rejection, a misinterpretation of a single value (especially in the surrounding of the detection limit) is
possible. Therefore, the user should always take care for the frequency of "U
sampling. Just one single "U
statistical fluctuation.
11. Calculation of the average activity concentration
The LLRD activity collected on the filter is proportional to the exposure and finally to the dose.
Therefore, the exposure is the primary result for the calculation of the average activity concentration
by division by the exposure time. The accumulated exposure time remains in the memory even if the
measurement will be interrupted. The recently calculated result of the average concentration is
always related to the whole exposure period. It is necessary to make sure that filter activity and
exposure period are always consistent. Therefore, the exposure timer will be re-set after each filter
step. That means, a new exposure period starts automatically with a filter movement. Triggering the
filter movement by a fixed (short) interval allows to measure actual concentrations. Please note that
the exposer time will be re-set also in case of power off/on using the key switch.
Please note that any presented result within the stored time distribution represents always the
average concentration of the period from the last filter movement to the related time stamp. The
result does not represent the actual concentration in that moment.
SARAD GmbH 2023
) and others. The dose coefficient (respective DAC values) for U
nat
or only Plutonium (or other) is present at the place of
nat
dose coefficient, the phrase "*Unat*" appears on the display (if
nat
" reading within a number of LLRD results indicates definitely a
nat
Manual_Aer 5400_EN_27-04-2023.docx
. In both cases, the presented dose value
nat
and other nuclides has been collected. This
nat
or Plutonium.
nat
Aer 5400
nat
is the single carrier of
nat
" appearances during
nat
is
nat
nat
17
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