Browsing by Author "Anim-Sarpong, S."
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Item Epiboron instrumental neutron activation analysis for the determination of iodine in various salt samples.(2002) Nyarko, B.J.B.; Serfor-Armah, Y.; Osae, S.; Akaho, E.H.K.; Anim-Sarpong, S.; Maakuu, B.T.Epiboron instrumental neutron activation analysis (EINAA) using flexible boron as thermal neutron filter, has been used to analyze several salt samples obtained from various markets in Ghana for iodine. The method involves the irradiation of samples in boron carbide-lined polyethylene vials at the outer irradiation site of the Ghana Research Reactor-1 (GHARR-1). The samples were then counted directly without any pre-treatment on a Canberra N-type HPGe detector. The qualitative and quantitative analyses were done using the 443 keV photopeak of 128I. The precision and accuracy of the method have been evaluated and the detection limits of the various samples were calculated. The values of iodine determined in the iodized salt range between 10.0 and 210 ppm. For non-iodinated salts, iodine levels were below 500 ppb. The values obtained show great variations among the salt samples, sample collection time and from market to market. This results show that the method can be successfully applied in the determination of trace amount of iodine in salt samples without any chemical separation.Item Feynman-α technique for measurement of detector dead time using a 30 kW tank-in-pool research reactor.(2002) Akaho, E.H.K.; Intsiful, J.D.K.; Maakuu, B.T.; Anim-Sarpong, S.; Nyarko, B.J.B.Reactor noise analysis was carried out for Ghana Research Reactor-1 GHARR-1, a tank-in-pool type reactor using the Feynman-? technique (variance-to-mean method). Measurements made at different detector positions and under subcritical conditions showed that the technique could not be used to determine the prompt decay constant for the reactor which is Be reflected with photo-neutron background. However, for very low dwell times the technique was used to measure the dead time of the detector which compares favourably with the value obtained using the ?-conventional method. © 2002 Elsevier Science B.V. All rights reserved.Item Geometrical effects on thermal neutron reflection of hydrogenous moderators using 241Am-be source.(2002) Akaho, E.H.K.; Intsiful, J.D.K.; Maakuu, B.T.; Anim-Sarpong, S.; Nyarko, B.J.B.Reactor noise analysis was carried out for Ghana Research Reactor-1 GHARR-1, a tank-in-pool type reactor using the Feynman-? technique (variance-to-mean method). Measurements made at different detector positions and under subcritical conditions showed that the technique could not be used to determine the prompt decay constant for the reactor which is Be reflected with photo-neutron background. However, for very low dwell times the technique was used to measure the dead time of the detector which compares favourably with the value obtained using the ?-conventional method.Item Instrumental neutron activation analysis of iodine levels in fourteen seaweed species from the coastal belt of Ghana.(2000-08-01) Serfor-Armah, Y.; Nyarko, B.J.B.; Carboo, D.; Osae, E.K.; Anim-Sarpong, S.; Akaho, E.H.K.Fourteen seaweed species were sampled from October 1997 to May 1999 along the rocky shores of Ghana, which is being washed by the Gulf of Guinea (part of the Atlantic Ocean). Instrumental neutron activation analysis (INAA) was used to measure the iodine levels in the species, with the basic aim of selecting seaweed species that are rich in iodine and hence can be used as supplement in the diet of humans. This is to help solve the problems associated with iodine deficiency disorders (IDD). The levels of iodine found in the seaweed species ranged between 55 to 804 ppm. The precision, expressed in terms of relative standard deviation, and accuracy of measurements are within ±5–10%. The results show high variability in and between species and among sampling sites. The high values of iodine concentrations in the macroalgae suggest that these marine organisms can be used as supplement in the diet of humans.Item Investigative studies on effect of reflector thickness on the performance of low enriched uranium-fueled miniature neutron source reactors.(2011) Odoi, H.C.; Akaho, E.H.K.; Anim-Sarpong, S.; Jonah, S.A.; Nyarko, B.J.B.; Abrefah, R.G.; Lawson, I.; Ibrahim, Y.V.; Birinkorang, S.A.; Boffie, J.Neutronics analyses were performed on the 30 kW(th) GHARR-1 facility to investigate the effects on increased beryllium annular reflector thickness on nuclear criticality safety and on the neutron flux levels in the experimental channels. The investigative study was carried out using the Monte Carlo code MCNP on a hypothetical LEU UO 2 core theoretically enriched to 12.6% and having the same core configuration as the present 90.2% enriched HEU U-Al core. The analyses were performed on four models consisting of a reference model with 10.2 cm annular reflector thickness and three new design modification models with increased reflector thickness of 10.3, 10.4 and 10.5 cm respectively. The simulations indicated average thermal neutron fluxes of (9.80 ± 0.0017)E+11 n/cm 2 s in the inner irradiation channels for the reference model, indicating a 2% decrease with respect to the nominal flux of 1.00E+12 n/cm 2 s. Relatively lower neutron fluxes were obtained for the modification models with an average of (9.79 ± 0.0017)E+11 n/cm 2 s, representing losses of 2.01% and 0.01% with respect to the HEU core and reference LEU model. © 2011 Elsevier B.V. All rights reserved.Item Measurement of neutron flux distribution in the irradiation channel in the Ghana research reactor-1 using monte carlo method.(2011) Abrefah, R.G.; Anim-Sarpong, S.; Nyarko, B.J.B.; Akaho, E.H.K.; Sogbadji, R.B.M.The Monte Carlo method was used to determine the neutron fluxes in the irradiation channels of the Ghana Research Reactor-1. The MCNP5 code was used for this purpose to simulate the radial and axial distribution of the neutron fluxes within all the 10 irradiation channels. After the MCNP simulation, it was observed that axially, the fluxes rise to a peak before falling and then finally leveling out. It was also observed that the fluxes were higher in the center of the irradiation channels; the fluxes got higher as it moved toward the center of the core. The multiplication factor (keff) was observed as 1.000397 ± 0.0007. Radially, the thermal, epithermal and fast neutron flux in the inner irradiation channel range from 1.15 × 1012 n/cm2.s ± 0.1018 × 1011 - 1.19 × 1012 n/cm2.s ± 0.1172 × 1011, 1.21 × 1012 n/cm2.s ± 0.1014 × 10 11 - 1.36 × 1012 n/cm2.s ± 0.1038 × 1011 and 2.47 × 1011 n/cm2.s ± 0.1120 × 1010 - 2.97 × 1011 n/cm 2.s ± 0.1255 × 1010 respectively. For the outer channel, the flux range from 7.14 × 1011 n/cm 2.s ± 0.1381 × 1010 - 7.38 × 10 11 n/cm2.s ± 0.208 × 1010 for thermal, 1.94 × 1011 n/cm2.s ± 0.1014 × 1010 - 2.51 × 1011 n/cm2.s ± 0.1281 × 1010 for epithermal and 3.69 × 1010 n/cm2.s ± 0.8912 × 108 - 5.14 × 10 10 n/cm2.s ± 0.1009 × 109 for fast. The results have shown that there are flux variations within the irradiation channels both axially and radially. © 2010 Elsevier Ltd. All rights reserved.Item Rhodophyta seaweed species as bioindicators for monitoring toxic element pollutants in the marine ecosystem of Ghana.(2001) Serfor-Armah, Y.; Nyarko, B.J.B.; Osae, E.K.; Carboo, D.; Anim-Sarpong, S.; Seku, F.Six seaweed species of the Rhodophyta family were sampled for atwo-year period from June 1996 to August 1998 along the Atlanticcoast of Ghana (part of the Atlantic Ocean). The species wereanalysed to determine the levels of eleven chemicalelements namely: Al, As, Br, Cd, Fe, La, Mn, Ni, Hg, V and Zn byInstrumental Neutron Activation Analysis (INAA). Al, Br, Ni, andZn were measured in all the seaweed species studied. The elementAl generally showed the highest concentrations in most of thespecies analysed while Hg levels were the lowest. Precision andaccuracy of the method have been evaluated and the detectionlimits also calculated. The results showed high variability inand between species, among sampling sites and times ofcollection. The high values of metal concentrations in themacroalgae suggest that these marine organisms can be used asbiological indicators for studing marine pollution.Item Thermal neutron reflection method for measurement of total hydrogen contents in Ghanaian petroleum products.(2001-11-01) Akaho, E.H.K.; Jonah, S.A.; Dagadu, C.P.K.; Maakuu, B.T.; Adu, P.S.; Anim-Sarpong, S.; Kyere, A.W.K.A fast and non-destructive technique based on thermal neutron reflection was used to determine total hydrogen contents in petroleum products available in Ghana. A source holder consisting of an 241Am-Be neutron source and 3He neutron probe designed for detection of liquid levels was used to measure reflection parameter as a function of hydrogen contents in liquid hydrocarbons which served as standards. The measured data were fitted to two linear equations for two different geometrical arrangements. The trend of data was found to be consistent with theoretical analysis based on neutron moderation. The calibration lines were used to determine hydrogen contents in 10 petroleum products. The results agree favourably with those obtained using different experimental set-ups with other neutron sources and probes. The technique was also used to determine the quality of diluted petrol with aviation fuel.Item Transient analysis of Ghana research reactor-1 using PARET/ANL thermal-hydraulic code.(2009) Amponsah-Amoako, E.; Akaho, E.H.K.; Anim-Sarpong, S.; Nyarko, B.J.B.