Further considerations for the setting up of a low background whole-body counter for internal dosimetry at Waste Isolation Pilot Plant (WIPP) Carlsbad, NM, USA: transmitted photon component.

One of the further considerations in the present work, while setting up a low background whole-body counter (WBC) underground at the Waste Isolation Pilot Plant (WIPP) is to reduce the background in the energy region of interest <100 keV. The goal of the present work is to determine the adequacy of a chamber located underground at WIPP of dimensions 1.83 m × 1.22 m at the base, 1.83 m high, with 15 cm thick pre-world-war II steel shielding. The objective of the present work is to estimate the transmitted photon flux into this chamber for setting up the low background WBC. The transmitted photon flux is simulated with the GEANT code for an incident photon flux consisting only of 1461 keV photons. The results are discussed with respect to a detector of choice for detecting <50 mBq emitting photons in the energy region <100 keV.

Internal dosimetry of 210Pb in the human cranium: preliminary results from instrumentation needs for in vivo counting in a low-background underground counting facility.

Internal dosimetry of (210)Pb in the cranium deals with the determination of the amount of energy deposited in tissue by (210)Pb radiations within the cranium. (210)Pb in the human cranium was monitored by in vivo counting in a low background facility 640 m (2100 ft) underground with a germanium (Ge) gamma-ray detector having a beryllium window. The minimum detectable activity (MDA) was established with this system to be 0.2 Bq (5 pCi) in 25-h counting time with a 15-mm diameter and 7-mm thick Ge detector, having a beryllium window of thickness of 0.08 mm, in contact with the cranium just above the ear adjacent to the temple region. To establish an MDA of 0.004 Bq (0.1 pCi) with this system, the limitation arising from the ambient radon level at 10 Bq m(-3) was investigated.