Gross beta particle

When gross beta particle activity exceeds 50 pCi L radioactive constituents must be identified total body doses must be calculated. 

Gross beta particles and photon emitters (man made)... 

If the gross beta-particle measurement is well in excess of the total beta particle activity inferred from gamma-ray spectral analysis, then radionuclides that emit only beta particles must be measured. The search usually can be narrowed by information on other radionuclides or from screening. The relatively few radionuclides that emit energetic beta particles but not gamma rays include Sr, °Sr, 91Y, 99tc, and i i Pm. Methods presented in Chapter 6 can be tested for obtaining... 

Radionuclides that emit only low-energy beta particles may not be detected by gross beta-particle analysis with an end-window proportional counter, but can be detected, although at low efficiency, by LS counting. These radionuclides include... 

Selenium Gross beta particle activity (dissolved)... 

Gross alpha and gross beta activity can be determined by various radioactive counters, such as internal proportional, alpha scintillation, and Geiger counters. Radium in water can be measured by co-precipitating with barium sulfate followed by counting alpha particles. Radium-226 can be measured from alpha counting of radon-222. Various methods are well documented (APHA, AWWA, and WEF 1998. Standard Methods for the Examination of Water and Wastewater, 20 ed. Washington DC American Public Health Association). 

Beta particles Gross alpha 4 mrem 4 mrem RO... 

Air filters and gummed deposition collection films first are measured by gross alpha- and beta-particle counting and gamma-ray spectral analysis. Usually, 1/2 of the sample then is dissolved to perform radiochemical analysis of the deposited radionuclides. The filter can be dry ashed, and then totally dissolved with an HNO3-HF treatment. 

The sample may arrive unliltered or separated as filtered water and the filter that contains the solids. The water sample is preserved with dilute acid or a preservative suitable for a radionuclide such as 1 that may be lost from an acid solution. Water without suspended solids is ready for evaporation to measure the gross alpha- and beta-particle activity, measure gamma rays by spectral analysis, and perform radiochemical analysis. The solids usually are counted similarly and then processed for dissolution as described in Section 6.2.1 for subsequent radionuclide analysis. 

Paper or cloth smears are used, often in response to regulations, to wipe surfaces of specified area (e.g., 100 cm ) to check for removable radionuclides. The smears are counted directly by gamma-ray spectral analysis. For gross alpha- or beta-particle measurements, thin smears are counted in a proportional counter or immersed in a cocktail for LS counting. Further analysis for a radionuclide of interest that emits... 

Screening measurements for gross alpha and beta particles may not be particularly useful for fission-product mixtures because generally alpha particles are at extremely low concentration and beta particles are contributed by numerous radionuclides. A gross screening measurement is useful for suggesting additional analyses if it clearly exceeds the sum of the radionuclides measured individually. 

Determination of gross alpha- or beta-particle activity is a measurement for which the source is prepared for counting without chemical separation. The measurements are performed to ... 

An aqueous sample may be added to the cocktail directly, after minor prior processing, or at the end of a radiochemical separation procedure. Direct addition is the equivalent of gross activity counting discussed in Section 7.2.4 except that some spectral analysis may be possible. Alpha particles can be differentiated from beta particles by deposited energy, pulse shape, and decay time. Self-absorption is of no concern. Quenching and luminescence, discussed in Section 8.3.2, often occur. Identification by maximum beta-particle energy is approximate, and requires comparison to radionuclide standards. 

Initial gross alpha- and beta-particle counting... 

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