Montaha Behbehani

Baseline concentration of 210Po in Kuwait's commercial fish species.

This baseline study highlights the (210)Po variation in whole fishes with different feeding habits. Whole-body (210)Po concentrations were determined in ten important commercial fish species found in the northern Arabian Gulf to serve as baseline data. Primarily, (210)Po is absorbed from water, concentrated by phytoplankton and microzooplankton, and then transferred to the next trophic level along the marine food chain. The lowest concentration of (210)Po was measured in larger carnivorous fishes like hamoor (0.089 Bq kg(-1)), while the highest was found in the fishes that feed on algae, zooplanktons and detritus, like battan (3.30 Bq kg(-1)). The baseline data can be used to understand both the trophic transfer of (210)Po in the marine food chain and the (210)Po concentration factors in fish from the Arabian Gulf.

Concentration of selected radionuclides in seawater from Kuwait

No baseline existed for the radionuclides in Kuwait territorial water. With changing trend in the region to embrace nuclear energy, the baseline study is imperative to create a reference and to record the influence-functioning of upcoming power plants. The first one in Bushehr, Iran is ready to start and several more are likely to come-up in UAE, Saudi Arabia and Kuwait. The present baseline concentration of the four considered radionuclides show low concentration of tritium, polonium, strontium and cesium; their concentration is comparable to most oceanic waters.

STUDIES ON DEPOSITS OF SPENT HYDRO-TREATING CATALYST: A STUDY BY COMBINED ANALYTICAL TECHNIQUES

ABSTRACT Carbonaceous and non-carbonaceous deposits on a Ni-Mo catalyst, stemming from atmospheric residue upgrading in an ARDS unit were subjected to a combination of analytical techniques, i.e. SF extraction, TGA/DTA/MS, DRIFT, l3C CP-MAS NMR, XRD and elemental analysis. Since the spectroscopic features of several components of the deposit interfere with each other a detailed deposit characterization was only achieved by stepwise removal of certain components by SFE deoiling and calcination. SF extraction stripped about 22 wt % of the carbonaceous deposit of the spent catalyst increasing the sp2/(sp3 + sp2) ratio of the NMR-visible carbon from 0 63 to 0.67. TGA revealed three separate temperature ramps for stepwise driving off of deposited material- first ramp, 30° C - 280° C, loss of oil and sulfur from metal sulfides; second ramp, 280° C - 450° C, loss of carbonaceous material like coke; third ramp, 500° C - 680° C, loss of metal sulfates. Further calcination up to 1000° C has no effect on the metal c...

Plutonium and cesium baseline concentrations in seawater from northern Arabian Gulf

The Arabian Gulf is a semi-enclosed water body that has witnessed accelerated anthropogenic activity, in terms of commissioning of nuclear power plants, desalination facilities, oil refineries and extensive coastal development. Furthermore, three wars during the past three decades is a potential worry. This study presents the first plutonium baseline in seawater from the Northern Arabian Gulf. The 239+240Pu concentrations in seawater vary, between 2.9 and 4.9mBqm-3, a range that is comparable to other water masses at this latitude. The 238Pu ranged between 0.04 and 0.05mBqm-3 and the 137Cs concentration between 1.04 and 1.18Bqm-3. The ratio of 238Pu/239+240Pu at all eight sampling stations was 0.01, while the ratio of 239+240Pu/137Cs varied between 0.01 and 0.02. The presence of 137Cs and 239+240Pu in seawater from this region can mainly be attributed to the global atmospheric deposition and fluvial transport. The seawater concentration of 239+240Pu is five order of magnitude lower than bottom sediments in the area.

Baseline radionuclide specific activity in commercial fishes of Kuwait

Radionuclide concentration in commercial fish species of Kuwait has been determined primarily with the intention of creating the baseline for 210Po, 137Cs, 40K, 226Ra, 224Ra, 228Ra, and 90Sr. This baseline information can be useful for issuing food advisories and determining annual intakes and radiation doses due to fish consumption. The highest fresh weight concentration of 210Po and 90Sr was in Battan and the lowest in Sobaity. Highest fresh weight 40K concentration was observed in Meid and the lowest in Battan. The 224Ra, 226Ra and 228Ra concentrations were highest in Meid, whereas the lowest was in Nuwaibi. In all the collected fish samples, 137Cs was below the detection limit.

Concentrations of selected radionuclides and their spatial distribution in marine sediments from the northwestern Gulf, Kuwait

This study focuses on creating a baseline for 40K, 210Pb, 137Cs, 90Sr, 226Ra, 228Ra, 238U, 235U, 234U, 239+240Pu and 238Pu in marine sediments in the northwestern Gulf. The respective measured concentration ranges were 386-489, 32.3-48.8, 1.5-2.9, 4.53-5.42, 18.3-23.1, 18.8-23.0, 22.3-30.5, 0.99-1.33, 25.6-34.8, 0.30-0.93, and 0.0008-0.00018Bqkg-1. The levels of these radionuclides are generally comparable to values reported for other marine waters in the northern hemisphere. The 137Cs activity in the Gulf sediments offshore Kuwait is an order of magnitude lower compared to sediments from northeastern Iran. Other than that finding, no hot spots were observed in sediments adjacent to power and desalination plants, oil and gas industrial activities or wastewater treatment facilities. These data will serve as a baseline to gauge possible future inputs of radionuclides in the northern Gulf. The calculated average ratio of 235U/238U activity in the area is in agreement with the reported figure of the natural uranium ratio, suggesting the absence of depleted uranium (DU) at all the stations. The low concentration of 239+240Pu suggests that there is no significant source of plutonium except that from atmospheric fallout from weapon testing and possible dry deposition via long-range dust transport.

Naturally Occurring Radioactive Material (NORM) in seawater of the northern Arabian Gulf – Baseline measurements

This study focuses on creating baseline for 238U, 235U, 234U, 210Pb, 210Po and 40K concentrations in the northern Arabian Gulf. The respective concentration ranges were 0.047-0.050, 0.00186-0.00198, 0.054-0.057, 0.00085-0.00092, 0.00051-0.00062 and 18.6-19.1Bql-1. These results suggest that the levels are generally comparable to other marine waters in the northern hemisphere. There were no hot spots observed from oil and gas industry. These data will serve as a baseline to gauge possible future inputs of TENORMs in the northern Gulf. A positive and linear correlation was observed between 238,234U, 40K isotopes and seawater salinity. The results also suggest significant fractionation between 210Po and 210Pb, attributed to rapid removal of 210Po by biota compared to 210Pb. The mean residence time for 210Po in the study area was 371days. The 234U/238U and 238U/235U activity ratios in seawater samples vary between 1.14-1.15, and 0.038-0.040. The 234U/238U and 235U/238U ratio is similar to the expected composition of seawater (1.148±0.002) and 0.0462.

210 Po concentration in selected calanoid copepods in the northern Arabian Gulf

Copepods are the most abundant metazoans, forming a vital food chain link between the primary producers the phytoplankton and fish. This study presents baseline information on the concentration of 210Po among calanoid copepods isolated from the Kuwait marine area. The concentration of 210Po in six species of copepod, including Subeucalanus flemingeri, Parvocalanus crassirostis, Acartia pacifica, Calanopia elliptica, Acrocalanus gibber, and Euterpina acutifrons were 151.3-158.8 Bq kg-1 wwt, 121.1-129.5 Bq kg-1 wwt, 51.23-54.91 Bq kg-1 wwt, 38.88-40.09 Bq kg-1 wwt, 38.07-38.29 Bq kg-1 wwt, and 33.46-36.50 Bq kg-1 wwt, respectively. The 210Po concentration in seawater shows a seasonal variation, with a higher concentration range of 0.58-0.70 mBq L-1 during summer and autumn, while a lower concentration is found (0.30-0.38 mBq L-1) during winter and spring. The concentration factor among the copepods varies between 8 ∗ 104 and 5 ∗ 105 that is an order of magnitude higher than the diatoms and dinoflagellates.

Synthetic nanocomposite MgH 2 /5 wt. % TiMn 2 powders for solid-hydrogen storage tank integrated with PEM fuel cell

Storing hydrogen gas into cylinders under high pressure of 350 bar is not safe and still needs many intensive studies dedic ated for tank’s manufacturing. Liquid hydrogen faces also severe practical difficulties due to its very low density, leading to larger fuel tanks three times larger than traditional gasoline tank. Moreover, converting hydrogen gas into liquid phase is not an economic process since it consumes high energy needed to cool down the gas temperature to −252.8 °C. One practical solution is storing hydrogen gas in metal lattice such as Mg powder and its nanocomposites in the form of MgH2. There are two major issues should be solved first. One related to MgH2 in which its inherent poor hydrogenation/dehydrogenation kinetics and high thermal stability must be improved. Secondly, related to providing a safe tank. Here we have succeeded to prepare a new binary system of MgH2/5 wt. % TiMn2 nanocomposite powder that show excellent hydrogenation/dehydrogenation behavior at relatively low temperature (250 °C) with long cycle-life-time (1400 h). Moreover, a simple hydrogen storage tank filled with our synthetic nanocomposite powders was designed and tested in electrical charging a battery of a cell phone device at 180 °C through a commercial fuel cell.