Radioactive Aerosol Standards - Aerosols: Measurement, Dosimetry, and Health Effects - page 533

and to 1 × 10 −9 -1 × 10 −6 C m −3 for liquid electroaerosols. This installation was used for certifying
and testing ion counters, for measuring the electric characteristics of aerosol generated on other
physical-standard installations, and also in research work.
It was found in practice that the transmission of the VA unit of radioactive aerosols in three
stages—from the physical standard to the reference equipment and then to the working measuring
equipment—is optimal and can be used as a basis for developing test schemes for equipment used in
measuring the counted and mass concentrations of nonradioactive aerosols, as well as for equipment
used in measuring the aerosol's electrical parameters.
Thus, as a result of improving the special state standard for the VA unit of radioactive aerosols,
its metrological characteristics were raised and the reference and working VA measuring-equip-
ment errors reduced; the nomenclature of natural radioactive aerosols measured with standard was
extended and the range of generated monodisperse inactive aerosols increased.
20.2 CURRENTLY APPLICABLE RADIOACTIVE AEROSOL STANDARDS*
At the present time the State Standards in the form, which includes technique for generating and
measuring of parameters for both radioactive and nonradioactive aerosols in a wide range of sizes
and activities, do not exist in the world. Instead, there are, in some countries, local standards for
different groups of aerosols and radioactive gases.
20.2.1 r adon and i ts d ecay P roducts
In (Cotrappa et al., 1994) the application of National Institute of Standards and Technology (NIST)
of United States 222 Rn emanation standards for calibration 222 Rn is described. The NIST certiied
parameters include the 222 Rn strength and emanation coeficient. When a source of 222 Rn is loaded
into a leak tight jar of a known volume, 222 Rn will accumulate over time. It is possible to calculate
the time integrated average radon concentration after any given accumulation time. Radon detector
in the jar should be non-radon absorbing and a true integrator. In this case radon detector must yield
the theoretically predicted results. In case of consistent difference, the NIST traceable correction
can be derived.
The study NIST involves 34 randomly chosen electret ion chamber system (E-PERM) and 17
NIST sources. The procedures of calibration are enabled with simple equipment. E-Perm detectors
were found to give predicted measurement results with an accuracy of about 5%. Commercially
available continuous radon monitors also gave satisfactory performance. With the availability of
this technology, 222 Rn measurement instruments can be made NIST traceable—a great step forward
in radon metrology.
In (Budd et al., 1998) the study, within the framework of the International Atomic Energy Agency
(IAEA) and European Union (EU) International Radon Metrology Program (IRMP), the results of
the international intercomparison were presented in order to evaluate radon and radon decay prod-
uct measurement techniques. The work was organized jointly with U.S. Environment Protection
Agency Radiation and Indoor Environment National Laboratory (EPA) in Las Vegas, Nevada, and
the former U.S. Bureau of Mines (BOM).
The primary goal of this project was to compare the performance of radon and radon decay
product measurement instruments from around the world under both laboratory and ield exposure
conditions.
Nineteen organizations from 7 countries participated in this project with 32 types of radon and
radon decay product measurement instruments. The laboratory exposures were conducted in an
environmental radon chamber at EPA's Radon Laboratory in Las Vegas under very stable, con-
trolled environmental conditions at relatively low concentration of radon and radon decay products.
* This part of the section is based partly on information presented by D.E. Fertman and A.I. Rizin (JSC “SNIIP”) and Yu.V.
Kuznetzov and V.L. Kustova (GP VNIIFTRI) all Moscow, Russia.