LONG-TERM PERFORMANCE OF AN OPTICALLY STIMULATED LUMINESCENT SYSTEM FOR DOSE EQUIVALENT HP(10) MEASUREMENT.

The performance of an optically stimulated luminescent (OSL) passive dosimetry system named MicroStar reader manufactured by Landauer Inc and acquired in 2011 is assessed in this study. The assessment carried out is based on the results of the intercomparison (IC) exercises organised by the International Atomic Energy Agency in 2013 and 2021. The IC results show that this OSL reader can maintain good performance after long-term usage provided adequate maintenance and calibration operations are carried out. Moreover, this assessment also reveals the importance of using a higher number of measurements per data point for the non-linearity test of the IEC 62387 standard.

Monte Carlo optimum management of 241Am/Be disused sealed radioactive sources.

The optimum encapsulation of 241Am/Be disused sealed radioactive sources (DSRS) based on PHITS Monte Carlo simulations for their long-term storage in Cameroon was performed. The country capacity for the management of disused neutron sources was also evaluated and showed that a Am1 P60 capsule is sufficient for the total available inventoried 241Am/Be DSRSs. The effective dose rate was computed in the enclosures of the DSRS container, which will be temporarily stored in the centralized radioactive waste facility. The obtained results were in agreement with the ALARA principle for the exposure rate optimization and the obtained exposure dose rates were found to be 1.830 µSv/h (horizontal calculation) and 0.137 µSv/h (vertical computation) which values are lower than the 2.5 µSv/h acceptable limit for the public area. The dose profile for 241Am/Be source obtained, the neutron flux, and gamma generated from neutron absorption showed agreement with the research hypothesis. The Monte Carlo assessment achieved in the present research will be useful for dismantling and preparing the waste package for long-term storage.

Assessment of trace elements pollution and their potential health risks in the cobalt-nickel bearing areas of Lomié, East Cameroon.

A study of trace elements pollution in the cobalt-nickel mining area of Nkamouna-Kongo (East Region of Cameroon) and their intimation to the risk of human exposure was carried out. A large spatial variability of concentrations was observed in the geochemical analysis of the trace elements in the thirty samples investigated. Trace element pollution in the investigated samples was assessed using the Regional Screening Level calculator of Environmental Protection Agency (USEPA) and the collected sample were analyzed using a SPECTRO XEPOS Energy Dispersive X-Ray Fluorescence analyzer (ED-XRF). The trace element concentrations in the analyzed samples followed the following order: Fe > Cr > Mn > Zr > Ni > Ba > Rb > Cu > Zn > Sr > Ga > Pb > Co > Rb > As > Sn. The averages of trace elements contamination factors followed a decreasing order:: Cr > Ni > Fe > As > Co > Cu > Zr > Ga > Pb > Mn > Zn > Y > Rb > Ba > Sn > Sr. Enrichment factor studies revealed that chromium (Cr) was severely enriched (indicating that Cr is the main element of the anthropic load) while elements such as Ni, Ba, Mn, Co, Cu, Zn, Ga, As, and Pb were moderately enriched. The associated health risk of human exposure was investigated using the Regional Screening Level of Environmental Protection Agency. It was found out that the carcinogenic risk to the exposed population from ingestion is high (2.5E-03), while the dermal risk is moderate (7.08E-04) and the inhalation risk is low (2.50E-07). The total non-carcinogenic risk from trace elements exposure for adults (HI = 1.5) and children (HI = 1.47E + 01) indicates that non-carcinogenic effects may occur in the vicinity of the study area.

Recovering and restitution of unknown, unidentified, and unlabeled samples in laboratories using EDXRF analysis.

This Study presents a method to recover and label unknown samples in a nuclear laboratory using Energy Dispersive X-Ray Fluorescence (EDXRF) spectrometry based on spectra differentiation and analysis. This method was found to be a new powerful tool that can be used in different laboratories where a certain number of samples cannot be identified because they have never been identified, their labeling and identification cannot be assessed because of degradation, and/or any other causes. The method was found to be simple, timely appropriate, not expensive, and powerful in identifying and recover the information needed for a sample. The EDXRF spectrometry method for recovering unknown samples in laboratories was based on the following three main points:•EDXRF method allows the elemental characterization of any sample without clear identification in a laboratory;•The displaying of several samples' spectra on the same graph allows direct comparison and identification when the sample's data overlap one of the stored data; and•The identification of the unknown sample based on the EDXRF results: The faster method being the overlapping comparison while the elemental characterization-based identification needs high skilled expertise in X-ray fluorescence analysis.

Operational Measures Taken for the Authorization of X-ray Generators Used in the Medical Sector in Cameroon.

The use of x-ray generators for diagnostic radiology in the medical sector in Cameroon, Central Africa, is wide spread and on the increase in recent times. Regulatory control of x-ray machines used in medical sector has been achieved in the Littoral Region of Cameroon by means of notification and authorization systems, routine inspections, and enforcement programs. Quality control of x-ray equipment is performed to test the components of the radiological system and verify that the equipment is operating satisfactorily before issuance of the authorization with a validity of two years. The Licensee has the responsibility to conduct internal QC of their own x-ray equipment to insure their safe use and quality care to patients. After a 2-y period, the authorization shall be renewed and a new quality control is carried out. Because Cameroon is a developing country, second hand x-ray machines are imported and radiation exposure control is required to ensure protection of workers, patients, and the public by measuring physical parameters of the x-ray generators and imaging devices at the time of commissioning. Forty-five x-ray machines located in the Littoral Region of Cameroon are considered. The authorization/registration program is implemented in the whole country, but the considered x-ray machines were identified because of the high number of medical examinations due to patients and workers to whom the annual routine medical examinations are required by their employers. Is appears by the present study that around 45% of x-ray machines are inappropriate for diagnostic radiology. Based on their state of operation, enforcement measures are taken to maintain them or to prohibit their use. Appropriate training of staff under ionizing radiation is part of the effort to develop the necessary awareness about safety culture. The acquired knowledge and skills ensure the required protection and safety at workplaces.