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In situ radiation measurements are commonly used to detect radioactive material in luggage; at border control checkpoints; for in-field monitoring; during the illicit transfer of nuclear material; and at radioactive contamination sites, e.g., the Fukushima nuclear accident site. In considering the high brightness, fast decay time, and good energy resolution of cerium-doped lanthanum bromide [LaBr3(Ce)] scintillation detectors, this work conducted an experimental analysis aimed at evaluating the potential for applying LaBr3(Ce) detectors to in situ artificial radiation measurements. The effect of the intrinsic radiation of the LaBr3(Ce) detector was investigated. In addition, the intrinsic radiation contribution to the background radiation of the region of interest (ROI) under full-energy peaks for several artificial point sources and the minimum detectable activity (MDA) values of a 3 × 3-in. LaBr3(Ce) detector for several artificial radioactive point sources under unshielded (in the natural background) and well-shielded (in a low background chamber) conditions were calculated. The results indicate that the intrinsic radiation has a significant effect on the background radiation of the ROI especially when the full-energy peaks of several artificial point sources are located in the low-energy region or near 789 and 1400 keV. In addition, the MDAs (the measured time is 300 s) of the LaBr3(Ce) detector for 152Eu (121.78 keV), 133Ba (356 keV), 137Cs (661.7 keV), and 60Co (1332.5 keV) were 218.2, 63.6, 61.3, and 59.6 Bq, respectively, under unshielded conditions and 111.4, 39.1, 46.1, and 38.6 Bq, respectively, under well-shielded conditions. The intrinsic radiation also has some effects on the MDA of the LaBr3(Ce) detector, especially in the low-energy region. Thus, the drawback of its intrinsic radiation limits its application to in situ weak artificial radiation measurements, but LaBr3(Ce) detectors have the potential for use in medium- and high-radiation measurements due to the better energy resolution of these detectors than NaI(Tl) detectors. [ABSTRACT FROM AUTHOR]

A simple and economical passive graded shielding which is combination of low and high Z materials for HPGe detector for background radiation minimisation is developed for better identification of the peaks in acquired spectrum by reducing Compton continuum. The present paper discusses the design and advantages of the passive graded shielding (lead + copper + aluminium) which encloses the HPGe detector. The passive graded shielding improved sensitivity of the detector and reduced Minimum Detectable Activity (MDA) for planchet source from 19.6% to 11.7% for gamma photon energies in the range of 81-1408 keV and brought down the MDA, 35.25 GBq d

A simple and economical passive graded shielding which is combination of low and high Z materials for HPGe detector for background radiation minimisation is developed for better identification of the peaks in acquired spectrum by reducing Compton continuum. The present paper discusses the design and advantages of the passive graded shielding (lead + copper + aluminium) which encloses the HPGe detector. The passive graded shielding improved sensitivity of the detector and reduced Minimum Detectable Activity (MDA) for planchet source from 19.6% to 11.7% for gamma photon energies in the range of 81-1408 keV and brought down the MDA, 35.25 GBq d -1 and 35.26 GBq d -1 for 133 Xe and 135 Xe respectively which was 72.31 GBq d -1 and 78.27 GBq d -1 for noble gases in gaseous effluents before shielding of the detector. The passive graded shielding as integral part is considerably very useful for radiological protection at nuclear power/research reactors by minimising background radiation. [ABSTRACT FROM AUTHOR]

The article discusses a study which investigated how the Human Monitoring Laboratory (HML) of the National Internal Radiation Assessment Section (NIRAS) has reconfigured its whole body counter for the measurement of persons who might be internally contaminated. It describes the calibration, the minimum detectable activity (MDA), and potential dead time problems from high count rates resulting from high internal contaminations. Researchers set the background count rate to an average of the two results in detectors one and four.

This article discusses a study which aimed to check the hypothesized influence of total dissolved solids (TDS) on the counting procedure and offer countermeasures to compensate for this influence. The study conducted more than 600 measurements on samples to determine their gross alpha concentration. The analysis of the accumulated experimental data revealed an effect of the TDS values on the corresponding number of counts from the samples which may be due to self-absorption in the co-precipitated layer.

The article focuses on statistical hypothesis testing where a decision is made whether a measurement detected activity without counting for extended periods of time. An analysis of past comments on expressing the results of measurements precedes a discussion of why measurements should not be reported as less than the minimum detectable activity. The decision level is the value of the net count above which a measurement is deemed to have detected activity. This article is an extension of previous work restricted to paired counting, where the blank and sample were counted for the same amount of time, to blank count times greater than or equal to the sample count times.

Regulations on the release of a radioactively contaminated site for unrestricted use are currently being established by the EnvironmentalProtection Agency. The effective dose equivalent rate limit for the reasonably maximally exposed individual was proposed at 0.15 mSv y-1. The purpose of this study is to investigate whether or not maximum allowable soil concentrations of common radionuclides corresponding to 0.15 mSv y-1 are readily detectable. These maximum allowable soil concentrations were estimated using RESRAD. The RESRAD estimates account for an effective dose equivalent rate from external radiation plus the committed effective dose equivalent rate from internal radiation delivering 0.15 mSv y-1 to the reasonably maximally exposed individual. For Michigan and Arizona soil, the minimum detectable activities were calculated for a few radionuclides and compared to the RESRAD estimated maximum allowable concentrations. Considering only gamma-ray spectroscopy, this study found no evidence that concentrations of gamma-ray emitting radionuclides in soilcontributing to 0.15 mSv y-1 were undetectable. [ABSTRACT FROM AUTHOR]