Displaying publications 1 - 20 of 95 in total

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  1. Zal U’yun Wan Mahmood, Mei, Wo Yii, Abdul Kadir Ishak
    MyJurnal
    This study was performed to observe the variation in the distribution of 210Po,210Pb and 210Po/210Pb activity ratio throughtheir vertical profile of the sediment cores takenat surrounding Sungai Linggi estuary. Five sediment cores were takenin February 2011 and were cutto an intervalof 2 cm layer. Activity concentrations of 210Po and 210Pb were determined using alpha radiochemical analysis and gamma direct measurement, respectively. Generally, the measured activity of 210Po, 210Pb and 210Po/210Pbwere in the ranges of 22.73 –139.06 Bqkg-1dw., 37.88 –176.24 Bqkg-1dw.and 0.23 –1.34, respectively. The variation in the distribution profile for the radionuclides are believed to be influencedby human activities such as agriculture, fertilizer, vehicles, burned fuel fossil and forest, industrialand others via river input from land-base.Other factor is due to organic mattercontent played importantrole as the geochemical carrier to transportthose radionuclides at study area. It was provedthat hasa strong correlation between the radionuclide distribution and the sedimentcomposition of organic matter.Furthermore, in those rangesreflectedthat 210Pb activities were higher than210Po with an activity ratio average of 0.79. This is probably due to dramatic increase of excess 210Pb supplied from atmospheric deposition, in situ decay of 226Ra and as a result of diagenetic remolibilazationof 210Pbin deeper layesof the sediment column. Thus, thosefactors are majorcontributions on thevariation of 210Po and 210Pb in the sediment core at surrounding Sungai Linggi estuary.
  2. Zal Uyun Wan Mahmood, Yii, Mei-Wo, Che Abd. Rahim Mohamed, Norfaizal Mohamed @ Mohamad, Abdul Kadir Ishak
    MyJurnal
    The most commonly used techniques of alpha and gamma spectrometry were performed to measure
    210Pb activity in marine sediment core as a comparison. Alpha analytical technique measured the
    activity of 210Pb from it’s in-grow grand-daughter 210Po after a chemical separation, assuming
    radioactive equilibrium between the two radionuclides. Meanwhile, gamma analysis technique
    allows direct measurement, non-destructive and no preliminary chemical separation. Through the
    comparison, it is found that both alpha and gamma analysis techniques were slightly difference.
    Overall, the results from alpha analytical technique were basically higher than those from the
    gamma analytical techniques. Some logical argument had been discussed to explain this situation.
    In routine analysis, the analytical technique used should be chosen carefully based on advantages
    and disadvantages of the each technique and analysis requirements. Therefore, it is recommended to
    determine exactly the needs and purpose of analysis and to know the sample history before decide
    the appropriate analytical technique
  3. Radaideh, K.M., Matalqah, L.M., Tajuddin, A.A., Lee Luen, F.W., Bauk, S., Abdel Munem, E.M.E
    MyJurnal
    The ultimate check of the actual dose delivered to a patient in radiotherapy can be achieved by using dosimetric measurements. The aims of this study were to develop and evaluate a custom handmade head and neck phantom for evaluation of Three-Dimensional Conformal Radiation Therapy (3D-CRT) dose planning and delivery. A phantom of head and neck region of a medium built male patient with nasopharyngeal cancer was constructed from Perspex material. Primary and secondary Planning Target Volume (PTV) and twelve Organs at Risk (OAR) were delineated using Treatment Planning System (TPS) guided by computed tomography printout transverse images. One hundred and seven (107) holes distributed among the organs were loaded with Rod-shaped Thermoluminescent dosimeters (LiF:Mg,Ti TLDs) after common and individual calibration. Head and neck phantom was imaged, planned and irradiated conformally (3D-CRT) by linear accelerator (LINAC Siemens Artiste). The planned predicted doses by TPS at PTV and OAR regions were obtained and compared with the TLD measured doses using the phantom. Repeated TLD measurements were reproducible with a percent standard deviation of < 3.5%. Moreover, the average of dose discrepancies between TLDs reading and TPS predicted doses were found to be < 5.3%. The phantom’s preliminary results have proved to be a valuable tool for 3D-CRT treatment dose verification.
  4. Nazaratul Ashifa Abdullah Salim, Nur AfiqahHarun, Zainon Othman, Salmah Moosa, Siti Aminah Omar, Muhammad Azfar Azman, et al.
    MyJurnal
    For addressing the issue of adulteration and counterfeiting of the sources of origin for the edible bird’s nests (EBNs), a preliminary study of elemental characterization for their geochemical markers was performed. This study aims to characterize the elemental profiles as geochemical markers and evaluate the relationships between these markers which could be used for the verification of the geographical origin of EBN in Malaysia. EBN samples from house and cave nests that represent a range of geographical and environmental characteristics were analysed using Neutron Activation Analysis (NAA) technique. The method was validated by analysing the Standard Reference Material SRM-1515 (Apple Leaves) and SRM-1573a (Tomato Leaves) of NIST. A total of 18 elements were determined. The results showed a statistical analysis of one way ANOVA has proven that there have a significant different elemental profiles in both EBN, clearly V, As, Ba, Sc, Sm and Th were not detectable in the house EBNs. Therefore, initial finding could be concluded that those elements can be identified as the key elements for geochemical marker to differentiate the type of EBN. Furthermore the differnces probably due to natural presence of those elements as well as regional or location and seasonal variation factors affecting the dietry habits of the swiftlets.
  5. Faiz Ahmad, Zaiton Ahmad, Affrida Abu Hassan, Sakinah Ariffin, Norazlina Noordin, Shakinah Salleh, et al.
    MyJurnal
    The research on radiation induced mutation has been conducted as one of the promising method of plant breeding in Malaysia since 1980s. Nuclear Malaysia is leading research institute inMalaysia conducting plant mutationbreeding research. Gamma Greenhousefacility located in Nuclear Malaysiais one of the irradiation facilitiesto serve as a chronic irradiation facility for inducing mutation in various organisms including plants, fungi and microbes.Chronic irradiation refers to the exposure of materials at a lower dose rate over a long period of time. Previous studies have shown that this type of irradiation can minimize radiation damages to living materials and produces a wider mutation spectrum, therefore is very useful for trait improvements in irradiated organisms. Experiments on induce mutation using Gamma Greenhouse facility for crop improvement program have been conducted since its first operation in 2009. Various plant species including ornamental and herbal plants, food crops and industrial crops have been irradiated to improve their traits such as higher yield and biomass, pest and disease tolerance, higher bioactive compounds, longer bloom time and many others. Most of these crop improvement programs were done through collaborations with other agencies in Malaysia such as universities, research institutes and government departments. A number of publications on crop improvement using Gamma Greenhouse have been published inlocal and international journals as well as seminar presentations at national and international levels. The outputs from induced mutation via chronic radiation using Gamma Greenhouse could be of great interest for plant breeders dealing with improvement and development of new cultivars. This paper discusses the activities and achievement in plant breeding and improvement using Gamma Greenhouse Facility in Malaysia.
  6. Phua Choo Kwai Hoe, Halimi Mohd Saud, Khairuddin Abdul Rahim
    MyJurnal
    Gamma irradiation is widely used in sterilizationand mutagenesis,especially for plant breeding and crop protection. Microbial mutagenesisthrough gamma irradiation is mainly applied in fermentation industry. In agriculture, gamma irradiation is mostlyapplied in cropimprovement. Microbial mutagenesis is mainly applied against fungus and spore-forming bacteria,which are resistant to gamma irradiation.Response of microbes to gamma irradiation varies and depends on various factors. Reviewof previous works on gamma irradiation for microbial mutagenesis in agriculture may provide some information for the use of this method. Thegeneral view ongamma irradiation, its application,and mutagenesis are discussedin this paper. Further investigation onmicrobial mutagenesis should consider molecular changes,information on which is lacking in previous works.Moreover, studies on microbial mutagenesis are still lacking in Malaysiadespite having severalgamma irradiation facilities.Therefore, further studies on microbial mutagenesis should be conducted.
  7. Noriah Jamal, Humairah Samad Cheung, Siti Kamariah Che Mohamad, Ellyda Muhamad Nordin
    MyJurnal
    This paper aims at presenting preliminary results of a survey on physical factors, namely tube
    potential (kV), tube current exposure time product (mAs) and compressed breast thickness (CBT)
    during voluntary mammography screening using Full-Field Digital Mammography (FFDM) System
    in Malaysia. Retrospective data were collected from 1128 FFDM images of 282 women from three
    major ethnic groups (Malay, Chinese and Indian) who underwent voluntary screening
    mammography at Breast Centre, International Islamic University Malaysia from January to March
    2008. Results from the present study were then compared with results from the previous study on
    Screen-Film Mammography System (SFM) according to the ethnic group for both Cranio-caudal
    (CC) and Mediol-Lateral (MLO) views. We found that the mean kV for CC view for the three ethnic
    groups are Malay (28), Chinese (28) and Indian (28), and for MLO view are Malay (29), Chinese
    (28) and Indian (29). These values are higher than the kV for SFM which were Malay (26), Chinese
    (27) and Indian (26) for CC and Malay (26), Chinese (27) and Indian (26) for CC and MLO views
    respectively. The mean mAs for CC and MLO views for FFDM were lower compared to SFM
    systems. These values were Malay (104), Chinese (108) and Indian (91) for CC views and Malay
    (106), Chinese (105), and Indian (94) for MLO views for the FFDM system. The values for SFM
    system are for CC and MLO views were Malay (120), Chinese (106) and Indian (126), and Malay
    (166), Chinese (132), Indian (183) respectively. The median CBT for CC and MLO views increased
    by 27% and 7% respectively on the FFDM compared to the SFM system. In conclusion, the FFDM
    operates with higher kV, lower mAs, and higher CBT when compared with SFM system. Median
    CBT on CC and MLO view with FFDM system are 27% and 7% higher respectively compared to
    the SFM. We are currently collecting data on mean glandular dose with FFDM systems to assess
    how the change in local mammography practice influences this value. This will allow comparison
    with related data from other parts of the world.
  8. Muhammad Fakhrurazi Ahmad Fadzil, Siti Selina Abdul Hamid, Siti Najila Mohd Janib, Azahari Kasbollah, Syed Asraf Fahlawi Wafa
    MyJurnal
    Medical radioisotope is a small quantity of radioactive substance used for the purpose of diagnostic and therapy of various diseases. In Malaysia, the emerging of new nuclear medicine centers or institutions in both government and private sectors rose abruptly for the past few years. Currently, there are no data available on the usage and demand of these medical radioisotope or radiopharmaceuticals. The aim of this study is to assess current medical radioisotopes and radiopharmaceuticals usage and also to provide data on current medical radioisotope and radiopharmaceuticals demand for both private and government hospitals or institutions in Malaysia. A survey for a period of 3 months was conducted across Malaysia. The survey was divided into five (5) main parts and it was distributed among healthcare professionalsinvolved working with medical radioisotope and radiopharmaceuticals in private, government and university based hospitals or institutions and was distributed manually either by hand, mail ore-mail.Data is presented in either pie chart or bar chart. Survey results found out that the highest demand and the highest usage among all radioisotopes are Technetium-99m and radioiodine isotopes such as the iodine-131, iodine-131 MIBG, iodine-123 and iodine-123 MIBG. Technetium-99m is the backbone of nuclear medicine whereby more than 80% of Nuclear Medicine services utilize this radioisotope. Technetium-99m supply chain is unstable globally and in coming future, two main reactors that produce 60% of world Molybdenum-99 will shut down and the supply of molybdenum-99 will be disrupted. In radioiodine services, currently, Iodine-123 can’t be obtained in Malaysia and neighboring countries due to its short half-life. Iodine-123 is useful in diagnostic of thyroid related diseases. As for PET services, the highest demands are F-18 FDG and gallium-68 Generator. It is important for Malaysia to self-produced medical radioisotope and radiopharmaceuticals to meet the local market demand.
  9. Muhamat Omar, Zalina Laili, Abd Khalik Wood, Julia Abdul Karim, Zarina Masood, Mohd Fazli Zakaria, et al.
    MyJurnal
    A systematic study to assess the concentration of radionuclides in primary coolant and associated water samples from the operation of a TRIGA Mark II reactor has been carried out. The samples were transferred into appropriate counting container and were counted by efficiency-calibrated gamma spectrometer systems for several hours to obtain statistically adequate data for qualitative and quantitative evaluation of the radioactive materials presence. The primary coolant was found to contain various gamma emitting radionuclides including 24Na, 41Ar, 42K, 51Cr, , 54Mn, 56Mn, 60Co, 99mTc, 122Sb, 124Sb and 187W. Most of the detected radionuclides were inferred to be originated from activation products of (n,) nuclear reactions of elements of reactor components such as stainless steel and aluminium alloy used in the reactor system. The study confirms the integrity of the reactor system with no apparent release of any fission products radionuclide into the coolant water system.
  10. Zaidi Embong
    MyJurnal
    This review briefly describes some of the techniques available for analysing surfaces and illustrates their usefulness with a few examples such as a metal and alloy. In particular, Auger electron spectroscopy (AES), X-ray photoelectron spectroscopy (XPS) and laser Raman spectroscopy are all described as advanced surface analytical techniques. In analysing a surface, AES and XPS would normally be considered first, with AES being applied where high spatial resolution is required and XPS where chemical state information is needed. Laser Raman spectroscopy is useful for determining molecular bonding. A combination of XPS, AES and Laser Raman spectroscopy can give quantitative analysis from the top few atomic layers with a lateral spatial resolution of
  11. Rida Tajau, Siti Farhana Fathy, Mek Zah Salleh, Nor Azowa Ibrahim, Maznah Ismail, Kamaruddin Hashim
    MyJurnal
    The acrylated palm oil (APO) nanoparticle is a potential product that can be used as carriers in
    medical field. The main focus of the present study was to study the potential of the APO
    nanoparticles for used in a controlled drug delivery system. The microemulsion system is used as a
    medium to incorporate an active substance such as Thymoquinone (TQ) into the APO polymeric
    micelle and then the radiation technique is used as a tool for the synthesis of TQ-loaded APO
    nanoparticle. The nano-size TQ-loaded APO particles resulted the particle size of less than 150 nm
    with spherical in shape. The TQ release profile was carried out in potassium buffer saline (PBS)
    solutions (pH 7.4) at 37
    oC. And, the zero-order model has been used to determine the mechanism
    of the drug release from the corresponding nanoparticles, respectively. The TQ release was found
    to be sustained and controlled in pH 7.4. At pH 7.4, the release of TQ followed the zero-order
    model. The in-vitro drug release study showed a good prospect of the APO nanoparticle on being a
    potential drug carrier as there are toxic against colon cancer cells and not toxic towards normal
    cells. This suggested that the APO product produce using this radiation technique can be
    developed into different type of carrier systems for controlled drug release applications.
  12. Wo, Yii Mei, Hidayah Shahar, Zaharudin Ahmad
    MyJurnal
    Present of 241Am in the environment is being determined as part of surveillance and research
    programs related to nuclear activities. The separation of 241Am from environmental samples was
    carried out against the IAEA’s reference material by using an improved in-house radiochemical
    separation method through anion exchange column, followed by the electro-deposition on a
    stainless steel disc, and finally assayed on alpha spectrometry counting system. The resulting
    spectra showed good isolated peak, indicating a good separation of the radionuclide of interest.
    The analytical results were in good agreement with the certified value for IAEA-326 and IAEA-368
    with the calculated U-score was 0.36 and 0.82, respectively, showing no significant difference
    between the experimental and certified value. Using this method, distributions of 241Am in seabed
    surface sediment in the Exclusive Economic Zone of East Coast Peninsular Malaysia were studied.
    Samples were collected during June 2008 where the concentrations of 241Am were found to be
    ranged from < 0.08 to 0.36 Bq/kg, dry weight.
  13. Nita Salina Abu Bakar, Zal U’yun Wan Mahmood, Ahmad Saat, Abdul Kadir Ishak
    MyJurnal
    Anthropogenic airborne depositions of 210Po,
    210Pb and 210Po/210Pb in the mosses and surface soils
    collected at the vicinity of a coal-fired power plant were studied. The purpose of the study was to
    determine activity concentrations of 210Po,
    210Pb and 210Po/210Pb for assessing their variation
    accumulation in the mosses and surface soils collected at the vicinity of a coal-fired power plant.
    Other purposes were to determine their concentration factor (CF) in relation to track the potential
    source of those radionuclides and to identify most suitable moss species as a biological indicator
    for atmospheric deposition contaminants. In this study, different species of moss Leucobryum
    aduncum, Campylopus serratus, Syrrhopodon ciliates and Vesicularia montagnei were collected in
    May 2011 at the area around 15 km radius from Tanjung Bin coal-fired power plant located in
    Pontian, Johor. The activity concentrations of 210Po,
    210Pb and 210Po/210Pb in mosses were in the
    range of 76.81 ± 4.94 – 251.33 ± 16.33 Bq/kg dry wt., 54.37 ± 3.38 – 164.63 ± 11.64 Bq/kg dry wt.
    and 1.10 – 2.00, respectively. Meanwhile the ranges for those radionuclides in the surface soil
    were 33.53 ± 2.10 – 179.67 ± 12.15 Bq/kg dry wt., 20.55 ± 1.33 – 106.62 ± 6.64 Bq/kg dry wt. and
    1.61 – 2.44, respectively. Corresponding high ability of Leucobryum aduncum to accumulate more
    210Po and 210Pb, wide geographical distribution, most abundant and high CF, therefore, the
    findings can be concluded this species was the most suitable as a biological indicator for
    atmospheric deposition contaminants such as 210Po and 210Pb. Furthermore, it is clear the
    accumulation of 210Po and 210Pb in mosses might be supplied from various sources of atmospheric
    deposition such as coal-fired power plant operation, industrial, agriculture and fertilizer activities,
    burned fuel fossil and forest; and other potential sources. Meanwhile, the
  14. Nazaratul Ashifa Abdullah Salim, Roslanzairi Mostapha, Zainon Othman, Nor Afiqah Harun, Mohd Suhaimi Hamzah, Shamsiah Abdul Rahman, et al.
    MyJurnal
    Stable isotope analysis has widely been used to trace the origin of organic materials in various fields, such as geochemistry, biochemistry, archeology and petroleum. In past a decade, it has also become an important tool for food traceability study. The globalisation of food markets and the relative ease which food commodities are transported through and between countries and continentsmeans that consumers are increasingly concerned about the origin of the foods they eat. The natural abundance of stable isotope variation such as carbon, nitrogen, hydrogen and oxygen are usedas geographic tracersor marker to determine the geographic origin of fruits, crop, vegetables and food products from animal. The isotopic compositions of plant materials reflect various factors such as isotopic compositions of source materials and their assimilation processes as well as growth environments. This paper will discuss on stable carbon and nitrogen isotopic compositions inricethat been determined by Isotope Ratio Mass Spectromety, advantages, limitations and potential of other analysis applicationsthat can be incorporated in food traceability system.
  15. Zal U’yun Wan Mahmood, Zaharudin Ahmad, Che Abd Rahim Mohamed, Abdul Kadir Ishak, Norfaizal Mohammed
    MyJurnal
    The distribution, enrichment and pollution status of metals in sediment cores from the Sabah-Sarawak coastal waters were studied. Seven sediment cores were taken in July 2004 using a gravity box corer. The metals of Cu, Zn and Pb were analyzed by ICP-MS to assess the pollution status of the sediments. The sediment fine fraction and organic carbon content was also analyzed. Enrichment Factor (EF), Geoaccumulation Index (Igeo) and Pollution Load Index (PLI) was calculated as criteria of possible contamination. The results showed that collected sediments were composed with clay, silt and sand as 12 – 74%, 27 – 72% and 0 – 20%, respectively. Meanwhile, organic carbon contents were relatively low and constant over time, based on sediment depth profiles, and it did not exceed 5% at any sampling station. The average metal concentrations in sediment cores at all sampling station were distributed in the ranges of 1.66 ± 1.36 – 6.61 ± 0.12 μgg-1 for Cu, 26.55 ± 1.04 – 57.94 ± 1.58 μgg-1 for Zn and 3.99 ± 0.10 – 14.48 ± 0.32μgg-1 for Pb. According to calculations of EF, Igeo and PLI, it can be concluded that concentrations of Cu, Zn and Pb were not significantly affected by pollution from anthropogenic sources at the seven sampling locations. Thus, the metal content of Cu, Zn and Pb in sediment should not cause pollution problem to the marine environment of Sabah-Sarawak coastal waters and further response measures are not needed.
  16. Ismail Sulaiman, Khairuddin Mohamad Kontol, Faizal Azrin Abdul Razalim
    MyJurnal
    The indoor and outdoor radon concentrations in Cameron Highlands (Peninsular Malaysia) and Ranau (East Malaysia) were measured. The measurements were carried out using passive method based on CR-39 solid state nuclear track detector (SSNTD) (for indoor measurements in Cameron Highlands) and active method using continuous radon/thoron progeny monitor (for indoor and outdoor measurements in Ranau and outdoor measurements in Cameron Highlands). The mean indoor radon concentrations in Cameron Highlands and Ranau were 50 Bqm-3 and 1.5 Bqm-3, respectively. The mean indoor radon concentration in Cameron Highlands was slightly higher compare to the world average. The maximum value recorded was 97 Bqm-3 which is almost similar to WHO reference level. The mean outdoor radon concentrations in Cameron Highlands and Ranau were 7.4 Bqm-3and 1.7 Bqm-3, respectively. The outdoor concentrations were low and comparable to world outdoor average.
  17. Md Suhaimi Elias, Mohd Suhaimi Hamzah, Mohd Suhaimi Hamzah, Siong, Wee Boon, Nazaratul Ashifa Abdullah Salim
    MyJurnal
    Assessment of source and sediment quality was carried out on marine sediments collected from the Tuanku Abdul Rahman National Park. Enrichment factors (EF), pollution load index (PLI) and geo-accumulation index (Igeo) were used to identify the sources of pollution, degree of contamination and sediment quality, respectively. Elemental analyses of marine sediment samples were performed by using the Instrumental Neutron Activation Analysis (INAA). Results from the Tunku Abdul Rahman National Park of Sabah indicated that most of the elements are considered to be from lithological or natural origin with EF values of less than 2 except for As (10 stations), Cr (3 stations), Lu (5 stations), Mg (2 stations), Sb (6 stations) and U (3 stations). For the sediment quality, most of the study area can be categorised as unpolluted for most of the elements (Igeo value < 2) except for As, Cr, Lu, Mg, Sb and U. A few study areas were slightly low contaminated with As, Cr, Lu, Mg, Sb and U. The contamination of As, Cr, Lu, Mg, Sb and U in the study area can be categorised as moderate with Igeo values ranged from 1 to 2. Meanwhile, the results of PLI value for sediment were ranged from 0.93 to 1.47 (PLI < 50) indicating there are not required to perform drastic rectification measures for the screening of the elements in the Tunku Abdul Rahman Park. Overall, assessment of the sediment quality at the Tunku Abdul Rahman National Park showed a few elements such as As, Cr, Lu, Mg, Sb and U were slightly enriched while most of the elements were similar to background values.
  18. Norhayati Abdullah, Wong, Jeannie Hsiu Ding, Ng, Kwan Hoong, Ung, Ngie Min
    MyJurnal
    The assessment of surface dose is essential in radiotherapy to avoid deterministic effect or to
    reduce the severity of side effects from radiation treatment. In this study, the surface dose for breast
    cancer radiotherapy was measured using two types of dosimeter; Thermoluminescent Dosimeter
    (TLD) and Optically Stimulated Luminescent Dosimeter (OSLD). The study was performed on the
    left breast of female Alderson Radiation Therapy (ART) phantom. The treatment planning was
    carried out on the ART phantom to determine the homogeneity of dose distribution within the target
    organ is complied with the tolerance limits of 95% to 107% as recommended by the International
    Commission on Radiation Units and Measurements (ICRU)’s Report No. 50. From the treatment
    planning result, the phantom then was irradiated with 267 cGy dose per fraction for two beam
    fields; medial tangential and lateral tangential fields using a 6 MV photon beam produced from
    three-dimensional (3D) conformal radiotherapy. Result shows that the OSLD provides 25.7% and
    23.5% higher surface dose compared to TLD for medial tangential and lateral tangential fields,
    respectively. This condition may be due to higher effective point of measurement and angular
    dependence of the OSLD compared to TLD. As a conclusion, suitable dosimeter should be selected
    to ensure accurate estimation of surface dose could be made thus reduction of skin reaction to
    patient could be achieved.
  19. Fadzil, M.S.A., Mohd Noor, N., Tamchek, N., Ung, N.M., Alawiah, A., Abdullah, N., et al.
    MyJurnal
    The thermoluminescence kinetic parameters of Ge-doped flat fibre have been investigated comprehensively using the computerized glow curve deconvolution analysis. The Ge-doped flat fibre was irradiated to 6 MV and 10 MV photon beam with dose ranging from 100 cGy to 300 cGy. Analysis was done using WinGCF software on the dependence of the glow curve intensity on dose delivered and the determination of the trap parameters. Ge-doped flat fibre was found to be linear over the entire dose range explored for both 6 MV and 10 MV irradiations with r2 value of 0.9955 and 0.9933 respectively. The glow curve consists of five individual glow peaks. The peak height increases with increasing irradiation dose. The first peak (P1) is a dominant individual peak for low temperature peak (LTP) with the maximum temperature ranging from 167.4°C to 179.0°C for both beams studied. Meanwhile, peak (P4) is a dominant individual glow curve for high temperature peak (HTP) with maximum temperature for 6 MV and 10 MV and is observed between 264.5°C to 279.4°C. Peak 1 has the lowest activation energy which is less than 0.72 eV while peak 2 shows the highest activation energy (1.3 eV < Ea < 2.1 eV) which indicates the deepest electrons trap. The results showed that the peak integral will increases as the dose increases. The Ge-doped flat fibre demonstrated the second-order kinetic peak behavior by exhibiting the symmetric shape of the glow curve with high temperature half of the curve slightly broader than the low temperature half, which suggests the possibility of electron retrapping.
  20. Mohd Reusmaazran Yusof, Yusof Abdullah
    MyJurnal
    Nuclear grade (high-purity) graphite for fuel element and moderator material in Advanced Gas
    Cooling Reactors (AGR) displays large scatter in strength and a non-linear stress-strain response from the damage accumulation. These responses can be characterized as quasi-brittle behaviour. Current assessments of fracture in core graphite components are based on the linear elastic approximation and thus represent a major assumption. The quasi-brittle behaviour gives challenge to assess the real nuclear graphite component. The selected test method would help to bridge the gap between microscale to macro-scale in real reactor component. The small scale tests presented here can contribute some statistical data to manifests the failure in real component. The evaluation and choice of different solution design of biaxial test will be discussed in this paper. The ball on-three ball test method was used for assessment test follows by numerous of analytical method. The results shown that biaxial strength of the EY9 grade graphite depends on the method used for evaluation. Some of the analytical methods use to calculate biaxial strength were found not to be valid and therefore should not be used to assess the mechanical properties of nuclear graphite.
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