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AIR MONITOR AND PROTECTION--A COINCIDENCE-COUNT ALPHA PARTICULATE AIR MONITOR

Technical Report ·
OSTI ID:4735145
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The detection of the Pu/sup 239/ maximum permissible air concentration (MPC) of 2 x 10/sup -12/ mu c/cc is complicated by a varying background o3 natural alpha emitiers. The air concentration of radon and thoron, in particular, varies considerably with atmospheric conditions. Since one MPC of airborne Pu is only 4.44 x 10/sup -6/ dpm/cc, it is necessary to integrate the activity on a fixed filter to obtain adequate measurement sensitivity. Radon and thoron are also coliected on the filter, and at times may accumulate to several hundred times the required detection level for Pu/sup 239/. An instrument using coincidence counting techniques was developed to measure the Pu/sup 239/ air concentration levels. In the decay chain for radon, Ra C decays by beta emission to Ra C' which decays by alpha emission with a half life of 163 mu sec; and in the similar thoron chain, Th C decays by beta emission to Th C' which decays by alpha emission with a half life for 0.3 mu sec. Delayed coincidence-counting techniques are used to identify counts due to natural alpha particles, and these counts are subtracted from a total alpha count to provide a measurement of Pu/sup 239/ The developed instrumert can detect continuous airborne Pu/sup 239/ concentrations of 2 x 10/sup -11/ mu c/cc in about 90 minutes and 2 x 10/sup -12/ mu c/cc in about 900 minutes. These detection levels can be obtained with background Ra--Th concentration levels of 2 x 10/sup -10/ mu c/cc. (auth)
Research Organization:
General Electric Co. Hanford Atomic Products Operation, Richland, Wash.
DOE Contract Number:
AT(45-1)-1350
NSA Number:
NSA-17-010532
OSTI ID:
4735145
Report Number(s):
HW-SA-2554
Country of Publication:
United States
Language:
English

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Related Subjects

AEROSOLS
AIR
ALPHA PARTICLES
BACKGROUND
BETA PARTICLES
BISMUTH 214
CHEMISTRY
COINCIDENCE METHODS
CONTAMINATION
COUNTERS
DECAY
ERRORS
FILTERS
HALF-LIFE
LEVELS
MONITORING
MPC
PLUTONIUM 239
RADIATION DETECTORS
RADIOACTIVITY
RADIUM
RADON
RADON 220
SAFETY
STANDARDS
THORIUM