Two important parameters for utilizing Ko-standardization method namely, absolute peak efficiency at reference position and peak-to-total ratio at different geometrical positions using standard point sources and HPGe were experimentally determined. Coincidence correction factor, C, for reference position and certain nuclides were also calculated and all almost equal to one. The importance and implication of this work to the K0-standardization method are presented. Other essential nuclear parameters which have to be experimentally determined or obtained from literature are also presented.
Dua parameter untuk kegunaan kaedah pemiawaian K0 iaitu kecekapan puncak absolut pada kedudukan rujukan dan nisbah jumlah-ke-puncak pada berbagai kedudukan geometri telah ditentukan secara eksperimen. Punca titik piawai dan HPGe digunakan. Faktor pembetulan koinsiden, C, yang digunakan untuk kedudukan piawai dan beberapa nuklid telah dihitung dan semuanya mempunyai nilai hampir sama dengan satu. Kepentingan dan implikasi kerja ini kepada kaedah pemiawaian K0 dikemukakan. Parameter nuklear lain yang ditentukan secara eksperimen atau yang diperolehi daripada pustaka juga dibentangkan.
Characterisation of the leaching behaviour of coal fly ash from Tenaga Nasional Berhad (TNB) by using tank leaching test method has been reported. The leachability of the constituents such as major elements and toxic metals in the coal fly ash was studied. Eight renewed leachant solutions after 6 hours, 1, 2, 5, 8, 21, 36 and 64 days were investigated after filtration. The parameters namely pH, cumulative release regarding the major elements and toxic metals to duration were presented. The results showed that the pH solutions increased from pH 4 to neutral and remained stable during the test. It might have resulted from the large buffering capacity of the coal fly ashes. Five major elements namely Al, Ca, K, Mg and Na were detected with Ca concentration in the leachant solutions was the highest for all samples. Toxic metals such as As, Ba, Co, Cr, Mn, Ni, Pb, Se and Zn were found and the test showed consistent results on the As, Ba, Mn, Se and Zn in leachant solutions. The findings also showed that some of the toxic metal concentrations namely As, Ba, Cr, Pb and Se exceeded the maximum allowance of the guideline of drinking water quality in Malaysia and WHO. Obviously, proper waste management has to be applied in this scenario.
Fukushima Daiichi nuclear disaster led to radioactive contamination crisis was resulted from a series of system failures, nuclear meltdown and radioactive material releases, following the 9.0 magnitude of earthquake and tsunami on March 11, 2011. The objectives of this study were; to investigate the movement of radionuclides based on oceanography and morphology of Pacific Ocean and Southeast Asia (Malaysia); to estimate the time for radionuclides to reach Malaysia and to calculate the amount of total absorbed dose rate for selected marine biotas namely benthic fish and pelagic fish. ERICA code system was used because it has the ERICA integrated approach to assess the radiation risk of biota. The estimations of radionuclide discharge from Fukushima Daiichi nuclear disaster were based on Cs-137 (half-life of 30.17 years), I-131 (half-life of 0.02 years). The parameters such as discharge rate of radionuclides (Bq/s), water depth (m), the distance between the target coast of Malaysia and radionuclide release point (m), the distance between the receptor and radionuclide release (m) and the velocity of the water/ocean currents (m/s) were studied. The results showed that the minimum estimated arrival time of radionuclides to reach Malaysia is located in Sandakan, Sabah, which is approximated at 4.82 years (Dec 2015) with an average of 5.039±0.310 years after the accident. Meanwhile, maximum estimated arrival time of radionuclides to Malacca is 5.87 years (Jan 2017) with an average of 5.527±0.480 years. The lowest estimated total absorbed dose rate by benthic fish is 0.0583 μGy/h with an average of (6.33±0.71) × 10-2 μGy/h in Malacca whereas the highest estimated total absorbed dose rate by benthic fish is 0.0751 μGy/h with an average of (7.11±0.57) × 10-2 μGy/h in Sandakan, Sabah. Pelagic fish in Malacca shows the lowest estimated total absorbed dose rate of 0.00149 μGy/h with an average of (1.62±0.18) × 10-3 μGy/h whereas Sandakan, Sabah showed the highest estimated total absorbed dose rate of 0.00193 μGy/h with an average of (1.83±0.15) × 10-3 μGy/h. The total absorbed dose rate and risk quotient of ERICA code system show that for all reference organisms, the probability of exceeding the selected screening dose rate of 400 μGy/h by aquatic biota is below the probability selected. Therefore, no measurable population of chronic exposure effects would occur at this stage. Nonetheless, a normal experimental analysis of fish samples should be performed in order to monitor the radiation effects to marine ecosystem.
Bioremediation of crude oil using biostimulation and/or bioaugmentation was done by simulation study in the green house under uncontrolled environment temperature. In this study, the soil with indigenous microbes was spiked with Tapis crude oil at 200 g/kg. The microbial density of the amended soils was augmented by addition of fresh inoculum of microbial consortium which consist of Pseudomonas aeruginosa UKMP-14T, Acinetobacter baumannii UKMP-12T and seed culture two strains of fungi, Trichoderma virens UKMP-1M and Trichoderma virens UKMP-2M at ratio 1:1:1:1 (v/w). The amendment soil was added with 20% (v/w) of standardize consortium inoculum, 20% (w/w) of dried empty fruit bunch (EFB) and the effect of EFB was compared with 0.7% commercial fertilizer (v/w) which contain NPK (8:8:1). Soil with indigenous microbes was used as a control. Results showed total petroleum hydrocarbon (TPH) degradation for treatment added with NPK fertilizer was 70.36%, addition with EFB bulking agent 68.86% and addition of both NPK and EFB was 100% at day 30 of incubation. The control plot, 62% of TPH degradation was achieved after 30 days incubation.
A gradient of neutron flux distribution in an irradiation channel in research reactor is considered to have effect on the k0-instrumental neutron activation analysis (k0-INAA) measurement. A study has been carried out to determine: (1) the variation of the thermal to epithermal neutron flux ratio (f); (2) the epithermal neutron flux shape factor (!), and; (3) the neutron flux in an irradiation container at four selected irradiation channels, use being made of an Au-Cr-Mo monitor set. In this work, f was found to range from 15.5 – 16.3, while ! was found to range from 1.52 × 10-2 – 5.58 × 10-2. Additionally, within the selected irradiation channels the variation in calculated thermal neutron flux within one irradiation container was found to vary from 11.8% - 26.7%. The results of analysis have provided a determination of variation in the neutron parameters, f and !, and neutron flux between the irradiation channels and within the irradiation container.
The microbial composition in coastal water of the Port Dickson beach in Negeri Sembilan, Malaysia was analyzed using several microbial indicators for the purpose of selecting the best indicator for marine water pollution. The indicators studied were total coliform (TC), fecal coliform (FC), fecal streptococci (FS) and coliphage. Five locations were selected along the Port Dickson beaches and samplings were carried out in 1998 and 2001. The results showed an increase in the number of total coliform (TC), fecal coliform (FC) and fecal streptococci (FS) between these two sampling by 98.12%, 86.12% and 99%, respectively. The numbers of TC, FC and FS exceeded the recommended limit for recreational seawater based on U.S. EPA 1986 standard. There was a positive correlation between TC, FC and FS and negative to coliphages.