Evaluation of spurious readings in Los Alamos personnel TL dosimeters
This study investigates the possibility of tritium build-up in TLD-600 chips irradiated with neutrons and the causes of spurious readings in the Harshaw TLD cards used for personnel dosimetry. Experiments indicated that spurious readings in TLD-600 chips, previously irradiated with neutrons, might occur in cases where the cards had been accidentally read at temperatures lower than 300/sup 0/C as a result of bad contact between the hot finger in the reading system and the chips. Because a TLD card contains glue and paper bar-code labels, the postannealing is performed at 80/sup 0/C for 17 hours. This annealing procedure alone does not effectively deplete the high-energy traps, such as those near 260/sup 0/C, populated by high-LET (Linear Energy Transfer) particles. TLD-600 chips, irradiated on a phantom by 400 mrem of moderated fission neutrons, read at 240/sup 0/C, annealed at 80/sup 0/C for 17 hours, and then reread at 280/sup 0/C, showed residual doses as large as 200 mrem (equivalent photons). Calculations and experiments show that for neutron exposures around 1 rem of moderated fission neutrons with an average energy of 500 keV, the maximum build-up of dose as a result of tritium formation is less than 1 mrem. The dose build-up in properly annealed TLD-600 and TLD-700 chips, is nearly the same, even though the TLD-600 chips were previously irradiated by neutrons. Both kinds of chips show natural background accumulation. A mechanism for annealing the Harshaw cards at high temperatures, without destroying the label or the adhesive material, was developed and found to be useful. 7 references, 4 figures, 3 tables.
- Research Organization:
- Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
- DOE Contract Number:
- W-7405-ENG-36
- OSTI ID:
- 6416410
- Report Number(s):
- LA-10140-MS; ON: DE85001518
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
THERMOLUMINESCENT DOSEMETERS
DATA COVARIANCES
ANNEALING
BUILDUP
EXPERIMENTAL DATA
FISSION NEUTRONS
NEUTRON DOSIMETRY
PERSONNEL DOSIMETRY
TRITIUM
BARYONS
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
DATA
DOSEMETERS
DOSIMETRY
ELEMENTARY PARTICLES
FERMIONS
HADRONS
HEAT TREATMENTS
HYDROGEN ISOTOPES
INFORMATION
ISOTOPES
LIGHT NUCLEI
LUMINESCENT DOSEMETERS
MEASURING INSTRUMENTS
NEUTRONS
NUCLEI
NUCLEONS
NUMERICAL DATA
ODD-EVEN NUCLEI
RADIOISOTOPES
YEARS LIVING RADIOISOTOPES
440102* - Radiation Instrumentation- Radiation Dosemeters