Gross alpha and beta

Radioactivity in environmental waters can originate from both natural and artificial sources. The natural or background radioactivity usuaUy amounts to <100 mBq/L. The development of the nuclear power industry as weU as other industrial and medical uses of radioisotopes (qv) necessitates the deterrnination of gross alpha and beta activity of some water samples. These measurements are relatively inexpensive and are useful for screening samples. The gross alpha or beta activity of an acidified sample is deterrnined after an appropriate volume is evaporated to near dryness, transferred to a flat sample-mounting dish, and evaporated to dryness in an oven at 103—105°C. The amount of original sample taken depends on the amount of residue needed to provide measurable alpha or beta activity. 

Total cyanide Gross alpha and beta radioactivity Root elongation test... 

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. 

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. 

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

A COMPARISON OF ANALYTICAL METHODS FOR SCREENING GROSS ALPHA AND BETA RADIOACTIVITY IN WATER BY LIQUID SCINTILLATION COUNTING AND GAS FLOW PROPORTIONAL COUNTING... 

The classical approach consists of evaporating a known volume of water and measure the activity of the residue in a glass flow proportional counter (GFPC) an attractive alternative to classical methods is the ultra-low level liquid scintillation counting (LSC) coupled to alphaHxita discrimination. These methods allow rapid and simple determination of gross alpha and beta activities, which are simultaneously measured through alpha beta discrimination technique. 

A Comparison of Analytical Methods for Screening Gross Alpha and Beta Radioactivity... 

The equipment used for the measurement of gross alpha and beta activities were 1220 Quantulus Ultra Low Level Liquid Scintillation Spectrometer and low background gas flow proportional detector (10-channel Low-Level Planchet Counter LB 770 Berthold). 

The performance of the GFPC and LSC methods for the measurement of gross alpha and beta activity in water was evaluated by participating in Proficiency Tests (PT) organized by Instituto de Radioprotefao e Dosimetria IRD/CNEN, which is available on a routine basis three times per year. The results obtained for the measurement of gross alpha... 

When D results are within the interval -2 < D < +2, the performance of the laboratory is considered good, data with D < -3 or D > +3 indicate that the measurement system is out of control and the performance is not acceptable. In this evaluation, the best performance for the determination of gross alpha and beta activity in water was achieved by the LSC technique. 

The time necessary for the determination of the gross alpha and beta activity using the two methodologies, considering for both the initial step of pre-concentration of 16 hours, is... 

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). 

THE DETERMINATION OF GROSS ALPHA AND GROSS BETA ACTIVITY IN SOLIDS, FILTERS AND WATER - VALIDATION OF DUTCH PRE-NORMS... 

Four Dutch norms, important for the determination of alpha or beta emitters, have been validated. Gross-alpha and gross-beta measurements are very useful for fast and easy screening of environmental samples after a nuclear accident. 

NVN5636 - gross alpha and gross beta on filters [3]... 

The Determination of Gross Alpha and Gross Beta Activity in Solids, Filters and Water 39 2.2. NVN 5622 - gross alpha in solids... 

The gross-alpha and gross-beta activities were measured separately with a gas flow counter there were no alpha-to-beta spill-over issues. 

In the NVN 5636 intercomparison, six laboratories analyzed glass-fibre filters and membrane-filters for gross alpha and gross beta activity (see table 3 and table 4). The result for one laboratory was rejected as an outlier. 

This paper describes the analytical characteristics of four Dutch norms, dealing with the determination of gross alpha and gross beta activity in solids, filters and water [7]. A gross alpha activity is reported as an Am-equivalent and a gross beta activity as a equivalent (of course in the case where Am and are calibration nuclides). 

Through the sampling head, the pump unit feeds air to the detection head which contains a sequentially advanced filter cartridge that captures alpha and beta emitters for detection. The detection type is gross counting for beta, gamma and spectrometry for alpha particulates using dual passivated silicon detectors. 

Gross Alpha and Gross Beta Radioactivity (Total, Suspended, and Dissolved)... 

Channel A records true "gross" or "total" activity because it includes those counts associated with compton and auger electrons as well as alpha and beta activity. 

Besides specific radionuclide determinations, screening methods to determine radioactive elements levels are very useful tools prior to laborious and expensive analytical protocols allowing isotopic analysis. These screening tools could replace gross alpha and gross beta index providing information about total element concentration. In order to develop fully automated methodologies based on inexpensive instruments, and consequently affordable for any routine laboratory, spectrophotometric detection can be used for this purpose. 

NEN 5636 2006 - Radioactivity measurements - Determination of artificial gross-alpha activity, artificial gross-beta activity and gamma spectometry of air filters and the calculation of the volumic activity of the sampled air. NEN, Delft, The Netherlands (in Dutch). 

PJM Kwakman, ER van der Graaf and P de Jong. The validation of the Dutch prenorms NVN 5622, NVN 5627, NVN 5636 and NEN 6421. Gross-alpha en gross-beta activity in solids, filters and water. RIVM report 610013001/2006. (In Dutch). 

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