The evaluation of the 1001.03 keV gamma emission absolute intensity using fundamental parameter method.

The accurate evaluation of the absolute intensity of the gamma-ray transition 1001.03 keV of 234mPa is crucial for accurate determination of 238U in nuclear material and environmental samples. Over the last decades, a wide range of 1001.03 keV absolute intensity values were published by different researchers and ranged from 0.59 to 1.12%. Nowadays, one of the most commonly used values is 0.847 ± 0.008% that seems not accurate and would eventually lead to an overestimation of 238U activity concentration. The absolute intensity of 1001.03 keV gamma transition was re-evaluated using different fundamental parameter method (FPM) modes, uranium ore and granite samples, samples' geometries, sample-to-detectors' geometries and gamma ray spectrometers. The mean ± standard deviation of newly optimized absolute intensity value is 1.067 ± 0.084% with an average relative bias of - 20% from the commonly used value.

The re-evaluation of the 234mPa's 1001.03 keV gamma emission absolute intensity for the precise assessment of 238U.

In this study the commonly used f-value for the 1001.03 keV (0.835 ± 0.004%) energy transition of the 234mPa was re-evaluated due to an obvious consistent overestimation of the 238U activity concentration. Different calibration protocols, samples' matrices and geometries, and gamma-ray spectrometers were exploited in order to assure the accuracy of the derived data. An average positive relative bias of about 24% from the currently used f-value was estimating leading to newly adopted f-value of 1.037 ± 0.052%. This newly suggested f-value will lead to an improvement in the accurate assessment process of the 238U using gamma-ray spectrometry in both environmental and nuclear safeguard fields.

A simplified gamma-ray self-attenuation correction in bulk samples.

Gamma-ray spectrometry is a very powerful tool for radioactivity measurements. For accurate gamma-ray spectrometry, certain correction measures should be considered, for instance, systematic uncertainty in the photo-peak efficiency due to the differences between the matrix (density and chemical composition) of the reference and the other bulk samples. Therefore, gamma-ray attenuation correction factors are of major concern for precise gamma-ray spectrometry. Simple practical correction for the photo-peak efficiency, due to discrepancies in both the samples' matrices and densities (self-attenuation), is performed in this study. This study suggests a brief measurement of relative photons transmission through both reference and unknown bulk samples where the variations of photon transmissions are assumed to be linearly correlated to the samples' densities. Specific correction factors would be produced for each analyzed sample to be considered when their activities are calculated. Practically, the suggested method was verified and succeeded in improving the obtained results.