LOCATION AND EXAMINATION OF ALPHA-ACTIVE AIRBORNE DUST PARTICLES COLLECTED ON GLASS-FIBER FILTER PAPER

Journal Article · Tue Jan 01 04:00:00 EST 1963 · Ann. Occupational Hyg.

OSTI ID:4130845

Stevens, D C

A procedure is described for the location and examination of radioactive particles by autoradiography. The procedure was applied to samples collected in laboratories handling toxic alpha emitters in order to provide data on the size of active dust particles escaping from glove boxes and other remote handling facilities under normal working conditions. The method described is of limited value for BETA -active particulates due to difficulties in precise location. The filtering characteristics of glass fiber paper used (Type AGF/A) make it a very suitable collecting medium for air sampling. The filter paper is mounted in a cold-setting Araldite mixture and a nuclear emulsion film is floated on to the surface. Processing of the emulsion is completed while it is still in contact with the mount; in this way an unambiguous alignment of the active dust particle with its alpha tracks is obtained. The direct information obtained includes location, size, andd number of alpha -active particles in the presence of inactive dust. A count of the number of tracks from each particle permits an estimation of the activity-size distribution of the radioactive aerosol. A rough value of the specific activity of the particles can be calculated from exposure time and number of tracks per particle if a value for particle density is assumed. Information on specific activity may assist in identifying an unknown radionuclide. If the nuclide is known, a rough measure of specific activity can distinguish between particles of pure nuclide and contaminated dust. By measuring the radius of the track system (star) produced by an active particle and the depth of the particle below the emulsion, the range of the alpha particles in Araldite was calculated. The radius was measured using an eye-piece graticule calibrated against a stage micrometer, and the depth by means of the scale on the microscope fine focus drum. For 5.14Mev alpha parttcles from Pu/ sup 239/, the range in Araldite of density 1.0 g/cm/sup 3/ is about 33 mu while for U (energy 4.18 Mev) the range is about 23 mu . The method was found useful to confirm specific activity estimates, and for distinguishing small amounts of Pu on inert particles and particles of U compounds. (BBB)

• Research Organization: Atomic Energy Research Establishment, Harwell, Berks, Eng.
• NSA Number: NSA-18-005554
• OSTI ID: 4130845
• Journal Information: Ann. Occupational Hyg., Journal Name: Ann. Occupational Hyg. Vol. Vol: 6
• Country of Publication: Country unknown/Code not available
• Language: English

Related Subjects

AIR
ALPHA PARTICLES
ARALDITE
BETA PARTICLES
CONTAMINATION
DENSITY
DISTRIBUTION
DUSTS
EMISSION
FILTERS
GLASS
GLOVEBOXES
HEALTH AND SAFETY
MEASURED VALUES
MICROSCOPY
NUCLEAR EMULSIONS
NUMERICALS
PARTICLE TRACKS
PARTICLES
PLUTONIUM 239
RADIATION DOSES
RADIATION PROTECTION
RADIOACTIVITY
RADIOAUTOGRAPHY
RADIOISOTOPES
REMOTE HANDLING
RESINS
SAMPLING
STANDARDS
SURFACES
TOXICITY
URANIUM
URANIUM COMPOUNDS
VOLUME