This study presents a broad reactor physics analysis including, neutronic, burnup, and decay heat of the 'as-built' NIRR-1 LEU core performed using SCALE 6.2.3 code package. First, verification of neutronic parameters of the NIRR-1 was performed by modeling the reactor 'as-built' LEU core. Thereafter validation of the model was done by comparing calculated result with measured data during the commissioning of the reactor. The results showed that the estimated neutronic parameters using KENO-VI code of SCALE 6.2.3 code package are in close agree-ment with the measured data. Hence, KENO-VI can be used for detailed neutronic assessment of MNSRs. The total decay heat at the end of core life after operation for 216 EFPD was estimated to be 1620.15 W and was majorly due to the contribution from fission products which was estimated to be 1608.10 W. This value explains why MNSRs are cooled through natural convection of the coolant during operation and at shutdown conditions. Additionally, the burnup of the core was determined to be 0.53 wt% which is within the expected burnup for a typical MNSRs (less than1 wt%) with a core lifetime of about 200 EFPD (similar to 10 years). Furthermore, the mass of 239Pu buildup after 216 EFPD was far less than the IAEA category III nuclear material and indicates a huge advantage of research reactor conversion in reducing proliferation risk.

This paper includes a review of the natural background radiation of the Kingdom of Saudi Arabia. The review deals with natural radioactivity measurements conducted in the past few decades in the Kingdom. The numerous research works reviewed refer to different materials soils processed building material, terrestrial (dwellings) and mining sites. For the measurements, different experimental techniques were adopted. The highest mean specific activity of 238 U, 232 Th and 40 K in soil samples was found to be 39.0, 25.6, and 343.0 Bq/kg, respectively. While the world average values are 33, 45 and 420 Bq/kg, respectively. For building materials, the highest mean values for 226 Ra, 232 Th and 40 K were 89, 106 and 773 Bq/kg, respectively. The mean indoor and outdoor dose rates were 455 µGy/y (Riyadh City) and 883 µGy/y (Al-Khamis City), respectively. For the mining sites the mean values for 238 U, 226 Ra, 228 Ra, gross α and gross β, were 0.12, 0.33, 21, 0.78 and 2.44 Bq/kg, respectively. Based on the available data it is concluded that most of the natural background radiation levels in the measured locations were within acceptable limits, while a few isolated locations showed elevated dose rates. This review suggests that new improved radiological survey methods be employed to cover the entire country, and that areas identified with comparably high dose rates be re-assessed, especially, in dwellings and mining sites.

Abstract The Nigeria Research Reactor-1 (NIRR-1) is the first nuclear research reactor in the country. It was acquired as a training and educational tool for the development of a future nuclear energy programme in Nigeria. The project to build the reactor was initiated in 1996 under a tripartite agreement between China, Nigeria, and the International Atomic Energy Agency (IAEA) via a project and supply agreement (PSA). NIRR-1, a miniature neutron source reactor (MNSR) developed in China, was commissioned in 2004 with a highly enriched uranium (HEU) core. However, due to increased global security concerns over the threat of nuclear terrorism and increased insecurity in Nigeria, steps were subsequently taken to convert from the reactor to run on low enriched uranium (LEU), through a partnership with the IAEA and other countries. The conversion of NIRR-1 has denied non-state actors potential access to weapons-grade uranium, enhancing nuclear security in Nigeria and globally through permanent threat reduction.

The exposure of polymeric insulation in nuclear power plants necessitates the study of the effect of neutron irradiation on the mechanical and dielectric properties of neat and nano-filled polymeric-based insulation materials. The exposure of the materials to ionizing radiation can influence their dielectric and insulating properties. This work presents the influence of neutron irradiation on the dielectric behavior of neat and nanoparticle-filled Epoxy-TiO2 nanocomposite. The prepared neat and nanocomposite samples were exposed to neutron radiation in the Nigeria Research Reactor I (NIRR-I). The mechanical and dielectric analyses of the samples were performed before and after irradiation. The presence of 2 wt% TiO2 nanoparticles in the epoxy matrix resulted in optimum mechanical and dielectric behavior. While the presence of the nanoparticles seems to have a significant influence on the reduction of the mechanical degradation of the composite (39.96%-12.11% after exposure to 4.5 kGy), it does not have much influence on the reduction of the dielectric loss of the composite. The variation of temperature of the sample revealed that the 2 wt% nanoparticles filled polymer displayed higher relaxation activated energy. The research suggests that the filling of the epoxy polymer with 2 wt% TiO2 nanoparticles can modify the mechanical and dielectric relaxation behavior of the polymer composites. This could enhance the resistance of the composite material to the effect of radiation-induced degradation in the polymeric insulation.

In spite of the acceptability and production of Uranium Oxides (UO2) with Low Uranium Enrichment (LEU-UO2) fuel in commercial scale, the use of uranium–silicide (U–Si) in place of the UO2 is one of the promising concepts being proposed to increase the accident tolerance of nuclear fuels. In this study, SCALE 6.2.3 computational tools have been used to model the Nigerian Research Reactor-1 (NIRR-1) which is a typical Miniature Neutron Source Reactor (MNSR) and calculated the core neutronic parameters such as Clean Core Cold Excess Reactivity (CCER), Control Rod Worth (CRW), Shutdown Margin (SDM), Safety Reactivity Factor (SRF) and Neutron flux distribution for the Highly Enriched Uranium (HEU) and candidates LEU cores. The results showed a close agreement between the calculated and measured data. The bias between calculated and measured data was attributed to the computational limitation of this study that was caused by a limited number of particles histories used in criticality calculations. The neutronic performance of the U3Si2–Al, U3Si–Al and U9Mo–Al fuels indicated the suitability of these candidates LEU fuels for conversion of MNSRs from HEU to LEU. The observed reduction in the thermal flux of the candidate LEU fuels was attributed to higher inventory of U-238 in LEU fuels when compared with the HEU and further underscore the need to raise their thermal power by approximately 10% for efficient utilization of the MNSR in Neutron Activation Analysis.

At the Basement Complex geological province of central Nigeria, in the state of Niger, just northeast of the Bida Sedimentary Basin, there is the character of non-complexity and high uniformity in the local geology over an appreciable linear spread. This appreciation makes it a standard practice to do one-dimensional vertical electrical sounding surveys in the search for groundwater resources at this area with the expectation of reliable results. This seeming “simplicity” means that intense manual labour can be invested in acquiring a large data-field at a local area of survey where resources are not readily available to do a standard two-dimensional survey of the conventional kind. This is especially significant for the proposed area of development at the Gidan Kwano Campus of the Federal University of Technology, Minna, Thus, with this awareness and the use of the ABEM Terrameter 4000 equipment, the aim of this study was to do an intense acquisition of one-dimensional electrical resistance and concomitant induced polarization programme for this proposed area of development so as to achieve the objective of garnering information about exploitable groundwater locations before structural developments cover these points up. Typical point-to-point one-dimensional tandem electrical resistance and concomitant induced polarisation surveys were completed along east-west profile lines for about 309 survey stations of the available 441 principal locations of the 4 km2 extent of the proposed new development. After due processing and interpretation of the data-field of this survey, whilst remarking that the induced polarisation data-set was used herein as quality control “refiner” only, clusters of reliable groundwater locations were observed at the southwest end of the 4 km2 areal extent of the proposed new development. It conforms to the dip of the landform and comparatively significant overburden-material thicknesses observed over there. Interestingly, in a twist of serendipity, the series of diagonal subsurface “fault-lines” that connect one promising groundwater prospect with the other, describable by a prominent northeast-southwest dip, aligns exactly with the Kazaure-Karaukarau-Kushaka-Ilesha Schist Belt. In the modern geography setting of the present time, the Kazaure-Karaukarau-Kushaka-Ilesha Schist Belt actually traverses a lengthy diagonal across the landscape of Nigeria, cutting through such Nigerian states as Jigawa, Kano, Kaduna, Niger, Kwara, Ekiti, and Osun. There is virtually no surface indicator of this once-prominent schist belt and what this study reveals is its vestigial signature

Alpha emitting radionuclides have potential for the therapy of cancers because of their high linear energy transfer, and short range biologic effectiveness. Alpha emitter 225Ac(T1/2 = 10.0 days) is a potent nuclide for targeted radionuclide therapy. 225Ac excitation functions via 232Th (p,7np)225Th→225Ac, 232Th (p,6n2p)225Ac, 232Th (p,4nα)225Ac, 232Th (p,5n3p)225Th→ 225Ac, and 232Th (p,3nαp)225Ra→225Ac reactions were calculated by Empire 3.2 code up to 200MeV and compared with existing data. No single nuclear level density with a pre-equilibrium model produce results which agree with the existing experimental data all through the energy range. However, a hybrid of the different nuclear level densities with the Hybrid Monte Carlo Simulation (HMS) and the exciton PCROSS pre-equilibrium models at different energy range provide results which are in good agreement with the existing experimental data. Hence the preferred production route for the direct and indirect production of 225Ac has also been suggested.

The aim of the study is to carry out elemental analysis of traditional herbs used as medicinal plants for the treatment of diseases in southern Ethiopia. The medicinal plants are those frequently used by the local/traditional healers for the treatment of gastrointestinal diseases in the southern part of the country. The instrumental neutron activation analysis (INAA) technique was deployed using irradiation and counting facilities of the Nigeria Research Reactor-1. Results were obtained for some essential elements at various concentrations for six herbal medicines. The major elements found in samples analyzed include Ca, Mg, Cl, and K, whereas Al, Na, and Fe were found to be in minor concentrations. The estimated daily intake of the analyzed elements was determined and found to be below the upper tolerable limits set by FAO/WHO. Therefore, the results obtained from the analysis of these herbal medicinal plants can be useful for the treatment of diseases and pharmaceutical purposes.

The objective of the study is multi elemental analysis of four indigenous Ethiopian tuber crops using instrumental neutron activation analysis (INAA) technique in order to get scientific evidences about the status of essential, trace and non-essential elemental compositions. The samples were collected from Southern and South-western parts of Ethiopia. The irradiation and measurement were performed by using irradiation and counting facilities of the Nigeria Nuclear Reactor -1 (NIRR-1) and a HPGe detector setup at the Centre for Energy Research and Training (CERT), Ahmadu Bello University (ABU), Zaria, Nigeria. A total of 17 elements were determined at various concentration levels. The highest concentrations of K, Mg, Mn and Zn were found in Colocasia esculenta (L.) Schott, whereas; the concentrations of essential and trace elements; Ca, K, Mg, Na, Cl, Mn, and Zn were found to be high in the native Coccinia abyssinica (Lam.) Cogn tuber. The estimated daily intake values of the constituent elements from the consumption of these crops are below upper tolerable limits set by international organizations such as WHO and FAO.

The Nigeria Research Reactor-1 (NIRR-1) is one of the Commercial Miniature Neutron Source Reactors (MNSRs) sited outside China and scheduled for conversion under the auspices of Reduced Enrichment for Research and Test Reactors (RERTR) program. Since 2006, the reduction in the fuel enrichment of MSNR facilities from greater than 90% HEU cores to less than 20% LEU cores has been embarked upon. Consequently in this work, the physics parameters of three dispersion LEU fuels, which include U3Si, U3Si2, and U9Mo enriched to 19.75% were determined by the MCNP code to investigate their suitability for the conversion of NIRR-1 to LEU. The following reactor core physics parameters were computed for the LEU fuel options: clean cold core excess reactivity (ρex), control rod (CR) worth, shut down margin (SDM), neutron flux distributions in the irradiation channels and kinetics data (i.e. effective delayed neutron fraction, βeff and prompt neutron lifetime, lf). Results are compared with experimental and calculated data of the current HEU core and indicate that it would be feasible to use any of the LEU options for the conversion of commercial MNSR in general and NIRR-1 in particular from HEU to LEU.

The result for large sample irradiation are continuously piping into the Center for Energy Research and Training (CERT), Ahmadu Bello University, Zaria. Therefore, characterization of the irradiation channels that can accommodate large samples become a challenge. In the first series of trial for large samples irradiation through slant tube of NIRR-1 which is a miniature research reactor is necessary in order to compare with some standard values reported by the arena of researchers including nuclear regulatory bodies. The thermal to epithermal flux ratio (f), epithermal neutron flux distribution parameters (α) were determined using two slant tube channels of NIRR-1. The adopted methodology here is bared and cadmium covered monitor foils method. The vertical dipstick higher purity germanium detector (HPGE) was calibrated and used for the calculation. The f and α values were calculated as 111.8 and -0.04977 respectively. The good agreement between the certified and experimental values of the shaping factors was achieved.

The objective of this study is a quantitative and qualitative analysis of essential and trace elements of four indigenous Ethiopian spices and herbs using instrumental neutron activation analysis technique. Results obtained for 16 elements: Major elements; Mg, Cl, and K; Minor elements; Na, Fe, and Mn, Zn, Br. While Al, V, Sm, Sc, La, Ba, Eu, Rb were found in traces. The spices, Affromumom korarima and Lippa Adonesis var. Koseret sebsebe were found to be very good sources of essential trace elements like Fe, Zn and Mn. The highest concentration of Mg was found in Ajowan whereas K and Fe were measured in Coriander seeds. The average daily dietary intake of some essential elements from the use of these spices were found to be below the recommended upper limit by WHO.

The health effects due to exposure to non-ionizing radiation (electric and magnetic fields) from high tension cables (power lines) around Kaduna metropolis was investigated. A total of 187 measurements each for electric and magnetic fields from 11KV, 33KV, 132KV and 330KV categories of power line from different locations including a power transmission sub-station in Kaduna were taken and analyzed. These measurements were taken at 1m above the ground and at 10m from the base of the power line to about 100m away using Electro smog meter. The maximum measured values were 6.07V/m for electric field and 7.27µT for magnetic field for public exposure. Comparing these values with ICNIRP 2010 guidance level of 5KV/m and 200µT respectively, the measured values are about 0.12% and 3.6% respectively of ICNIRP 2010 guideline. For occupational exposure, the measured values are 7.94V/m and 8.54µT respectively and compared to ICNIRP 2010 values of 10KV/m and 1mT respectively for occupational exposure, the measured values are about 0.08% and 0.85% of ICNIRP2010 guideline.

Prompt neutron lifetime calculations have been performed for the NIRR-1 reactor HEU and LEU cores using the 1/v insertion and the Adjoint flux weighing methods. Results of calculations obtained for the HEU and LEU cores are respectively 57.3 +/- 0.8 and 47.5 +/- 0.7 for the 1/v insertion and 56.9 +/- 0.3 and 46.3 +/- 0.5 for the Adjoint flux. There is a good agreement seen between the two methods for both cores. The prompt neutron lifetime was observed to be shorter in the LEU than for the HEU as expected. However, the Adjoint flux weighing method seemed to be the easiest method in calculating the prompt neutron lifetime for NIRR-1.

The preliminary investigation of the activity concentration of Naturally Occurring Radioactive Materials (NORMs) in seven different medicinal plants; Anacardium occidentale, Azadirachta indica, Daniella oliveri, Moringa oleifera, Psidium guajava, Terminalia catappa and Vitellaria paradoxa by means of gamma spectroscopic analysis using a NaI[Tl] detector shows that the activity concentration of K-40 in the medicinal plants ranges from 74.59 +/- 2.19 Bq/Kg to 324.18 +/- 8.69 Bq/Kg with an average of 171.72 +/- 6.09 Bq/Kg. The highest activity concentration of K-40 was recorded for A. indica while A. occidentale had the lowest activity concentration. Ra-226 activity concentration varies from 10.79 +/- 4.24 Bq/Kg to 42.47 +/- 2.76 Bq/Kg with an average of 25.02 +/- 3.18 Bq/Kg. The lowest activity was recorded for P. guajava while the highest activity was recorded for V. paradoxa. For the activity concentration of Th-232, it ranges from 27.76 +/- 1.02 Bq/Kg to 41.05 +/- 1.05 Bq/Kg, with an average of 35.09 +/- 0.71 Bq/Kg. The lowest activity was recorded for V. paradoxa while the highest activity was recorded for T. catappa. The average annual committed effective doses due to ingestion of Ra-226, Th-232 and K-40 in the plants ranges from 0.00426 +/- 0.00050 mSv/yr to 0.00686 +/- 0.00044 mSv/yr with an average of 0.00538 +/- 0.00035 mSv/yr, the highest value was recorded for A. occidentale while P. guajava has the lowest, the results determined for all the plants are far below the worldwide average annual committed effective dose of 0.3 mSv/yr for an individual provided in UNSCEAR 2000 report indicating that the associated radiological health risk resulting from the intake of radionuclides in the medicinal plants is insignificant. Consequently, the medicinal plants of this study are considered safe in terms of the radiological health hazards. Copyright (C) 2015, The Egyptian Society of Radiation Sciences and Applications. Production and hosting by Elsevier B.V.