Beta contamination monitor energy response
Beta contamination is monitored at Los Alamos National Laboratory (LANL) with portable handheld probes and their associated counters, smear counters, air-breathing continuous air monitors (CAM), personnel contamination monitors (PCM), and hand and foot monitors (HFM). The response of these monitors was measured using a set of anodized-aluminum beta sources for the five isotopes: Carbon-14, Technetium-99, Cesium-137, Chlorine-36 and Strontium/Yttrium-90. The surface emission rates of the sources are traceable to the National Institute of Standards and Technology (NIST) with a precision of one relative standard deviation equal to 1.7%. All measurements were made in reproducible geometry, mostly using aluminum source holders. All counts, significantly above background, were collected to a precision of 1% or better. The study of the hand-held probes included measurements of six air gaps from 0.76 to 26.2 mm. The energy response of the detectors is well-parameterized as a function of the average beta energy of the isotopes (C14=50 keV, Tc99=85, Cs137=188, C136=246, and Sr/Y90=934). The authors conclude that Chlorine-36 is a suitable beta emitter for routine calibration. They recommend that a pancake Geiger-Mueller (GM) or gas-proportional counter be used for primarily beta contamination surveys with an air gap not to exceed 6 mm. Energy response varies about 30% from Tc99 to Sr/Y90 for the pancake GM detector. Dual alpha/beta probes have poor to negligible efficiency for low-energy betas. The rugged anodized sources represent partially imbedded contamination found in the field and they are provided with precise, NIST-traceable, emission rates for reliable calibration.
- Research Organization:
- Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
- Sponsoring Organization:
- USDOE Assistant Secretary for Human Resources and Administration, Washington, DC (United States)
- DOE Contract Number:
- W-7405-ENG-36
- OSTI ID:
- 314138
- Report Number(s):
- LA-UR-98-2942; CONF-980756-; ON: DE99001778; TRN: 99:003285
- Resource Relation:
- Conference: Health Physics Society annual meeting, Minneapolis, MN (United States), 12-16 Jul 1998; Other Information: PBD: [1998]
- Country of Publication:
- United States
- Language:
- English
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