Radioactive Aerosol Standards - Aerosols: Measurement, Dosimetry, and Health Effects - page 536

these interferences, the aerosol generation system also provides dust aerosols to CAMs, either as a
homogenous mixture with actinide aerosols and radon progeny or as separate aerosols.
Tests with computer-generated pulses were provided in order to understand which aspect of
CAM performance can be evaluated with sources and ambient radon progeny and which responses
must be evaluated with actual aerosols, including effect of alpha energy degradation from deposi-
tion of actinide particles in a ilter substrate. The Alpha Energy Spectrum Simulator has been used
to provide realistic electrical pulses to the instrument preampliier to simulate different temporal
concentration and combinations of actinide aerosols and radon progeny.
The minimum detectable activity and false alarm rates were also studied in the dynamic tests for
a range of radon progeny concentrations, and for conditions involving both the absence and presence
of plutonium.
Performance of different types of ilters was also studied.
It should be pointed out that in the future the comparison results of facilities such as ISPN and
Lovelace system should provide conidence that the results of the two systems do not contain unex-
pected bias.
The results of development and practical application of new radioactive source types (Special
Aerosol Sources [SAS]) are presented in Belkina et al. (1991). SAS are manufactured for certain
type of radiometers using model aerosols of plutonoium-239, strontium-ittrium-90 or uranium of
natural isotopes composition. The original technology for source production allows taking into
account the features of sampling, as well as geometry and conditions of measurement of the activity
in the sample.
The highest accuracy in calibration, certiication, and veriication of the radiometers can be
provided by using national standard precision equipment (Antipin et al., 1980). But its direct usage
for metrological provision of measurement technique is too expensive. At each stage of develop-
ment and usage, the measurement technique for metrological purposes should be performed with
an optimal cost-effective ratio.
The proposed method of manufacturing SAS includes radioactive substance depositing onto
a substrate, its ixation and substrate mounting into the frame-holder intended for measurement
device. The check of the radioactive substance ixation quality showed that relative activity varia-
tion of the sources with plutonium-239 after 1−4 days by the dry cotton tampon is within the limits
of registration instability (less than 5%). The authors have developed and tested the procedure
of certifying and verifying the nuclear power plant radiation security monitoring system aerosol
channels by using Sr-90-Y-90 SAS.
In Fertman et al. (1998), the problem of the Russian secondary standard for volume activity
of long-lived radio nuclides aerosols and System of international comparison was discussed. The
national standard design was practically reproduced as Russian secondary standard for volume
activity of long-lived radioactive aerosols (VET39-1-2005) in the metrological center of the State
Atomic Energy Corporation “Rosatom” in JSC “SNIIP” Moscow. It is used for the calibration,
certiication and veriication of the radiometers, and other metrological provision.
In addition, the important problems that arise in radioactive aerosols' metrology in the last decades
were resolved:
1. It was added to the generation of natural uranium aerosols.
2. Developing model aerosol sources SAS in order to test aerosol radiometers directly on the
consumer place.
Model aerosols are prepared in special generators mounted in the box. Parameters of model radioac-
tive aerosols' particle sizes were estimated by six-cascade impactor and radiometer type MS-01P.
Measurement showed that model radioactive aerosols are polydisperse with a maximum diameter
close to 1 micron. Thus, radionuclides and characteristics of model aerosols are close to similar
parameters of national standard (Antipin et al., 1980).