Displaying publications 1 - 20 of 135 in total

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  1. Excitation functions of proton- and deuteron-induced nuclear reactions on natural iridium for the production of 191Pt
    Obata H, Khandaker MU, Furuta E, Nagatsu K, Zhang MR
    Appl Radiat Isot, 2018 Jul;137:250-260.
    PMID: 29679927 DOI: 10.1016/j.apradiso.2018.03.021
    We studied the excitation functions of residual radionuclides produced via proton and deuteron bombardment on natural iridium in the energy ranges of 30-15 MeV and 50-15 MeV, respectively. A conventional stacked-foil activation technique combined with HPGe γ-ray spectrometry was used to measure the excitation functions for 189, 191Pt and 189, 190g, 192g, 194gIr radionuclide production. Theoretical thick target yields were estimated to be 172 MBq/µA h and 192 MBq/µA h via the 193Ir(p,3n)191Pt reaction at 29.6-17.5 MeV and the 193Ir(d,4n)191Pt reaction at 40.3-23.8 MeV, respectively. The feasibility of 191Pt production from an iridium target was discussed, and compared with previously reported methods for the production of 191Pt.
  2. X-ray spectra and quality parameters from Monte Carlo simulation and analytical filters
    Salehi Z, Ya Ali NK, Yusoff AL
    Appl Radiat Isot, 2012 Nov;70(11):2586-9.
    PMID: 22940409 DOI: 10.1016/j.apradiso.2011.12.007
    BEAMnrc was used to derive the X-ray spectra, from which HVL and homogeneity coefficient were determined, for different kVp and filtration settings. Except for the peak at 61 keV, the spectra are in good agreement with the IPEM report 78 data for the case of filtered beams, whereas the unfiltered beams exhibit softer spectra. Although the current attenuation data deviates from the IPEM 78 data by ~±0.5%, this has negligible effects on the calculated HVL values.
  3. Dosimetric assessment of Gadolinium-159 for hepatic radioembolization: Tomographic images and Monte Carlo simulation
    Musa AS, Abdul Hadi MFR, Hashikin NAA, Ashour NI, Ying CK
    Appl Radiat Isot, 2023 Sep;199:110916.
    PMID: 37393764 DOI: 10.1016/j.apradiso.2023.110916
    A common therapeutic radionuclide used in hepatic radioembolization is yttrium-90 (90Y). However, the absence of gamma emissions makes it difficult to verify the post-treatment distribution of 90Y microspheres. Gadolinium-159 (159Gd) has physical properties that are suitable for therapy and post-treatment imaging in hepatic radioembolization procedures. The current study is innovative for conducting a dosimetric investigation of the use of 159Gd in hepatic radioembolization by simulating tomographic images using the Geant4 application for tomographic emission (GATE) Monte Carlo (MC) simulation. For registration and segmentation, tomographic images of five patients with hepatocellular carcinoma (HCC) who had undergone transarterial radioembolization (TARE) therapy were processed using a 3D slicer. The tomographic images with 159Gd and 90Y separately were simulated using the GATE MC Package. The output of simulation (dose image) was uploaded to 3D slicer to compute the absorbed dose for each organ of interests. 159Gd were able to provide a recommended dose of 120 Gy to the tumour, with normal liver and lungs absorbed doses close to that of 90Y and less than the respective maximum permitted doses of 70 Gy and 30 Gy, respectively. Compared to 90Y, 159Gd requires higher administered activity approximately 4.92 times to achieve a tumour dose of 120 Gy. Thus; this research gives new insights into the use of 159Gd as a theranostic radioisotope, with the potential to be used as a90Y alternative for liver radioembolization.
  4. Differentiation of elemental composition of normal and malignant breast tissue by instrumental neutron activation analysis
    Ng KH, Bradley DA, Looi LM, Mahmood CS, Wood AK
    Appl Radiat Isot, 1993 Mar;44(3):511-6.
    PMID: 8472024
    Multi-elemental quantitative analyses of 15 paired samples of normal and malignant human breast tissue by instrumental neutron activation analysis are reported. The elements, Al, Br, Ca, Cl, Co, Cs, Fe, K, Na, Rb, Zn were detected. Significantly elevated concentration levels were found for Al, Br, Ca, Cl, Cs, K, Na, Zn in malignant compared to normal tissue. Although the role of elemental composition in breast cancer is unclear, this finding may be of importance as another parameter for differentiating normal from malignant tissue.
  5. Effects of gamma radiation treatment on three different medicinal plants: Microbial limit test, total phenolic content, in vitro cytotoxicity effect and antioxidant assay
    Khawory MH, Amat Sain A, Rosli MAA, Ishak MS, Noordin MI, Wahab HA
    Appl Radiat Isot, 2020 Mar;157:109013.
    PMID: 31889674 DOI: 10.1016/j.apradiso.2019.109013
    BACKGROUND AND AIM: The aim of this study is to evaluate the effects of gamma radiation treatment on three medicinal plants, namely Euodia malayana, Gnetum gnemon and Khaya senegalensis at two different forms; methanol leaf extracts and dried leaves respectively.

    EXPERIMENTAL PROCEDURE: The microbial limit test (MLT) studies indicated the suitable dosage of minimum and maximum gamma irradiation for leaf extracts as well as dried leaves of all the tested medicinal plants. Quantitative analysis of total phenolic content (TPC) analysis is based on calorimetric measurements determined using the Folin-Ciocalteu reagent with gallic acid (GA) used as the reference. In vitro cytotoxicity assay by using fibroblast (L929) cell lines was performed on each plant to determine the toxicity effect which sodium dodecyl sulfate (SDS) as the positive control. DPPH (2,2-diphenyl-1-picryl-hydrazyl) assay was conducted by using vitamin C and GA as the positive controls to determine the antioxidant property of each plant.

    RESULTS AND CONCLUSION: The MLT analysis indicated that the suitable dosage gamma irradiation for leaf extracts was 6-12 kGy and dried leaves were 9-13 kGy. The amount of GA concentration in each plant increased significantly from 30-51 mg GAE g-1 before treatment to 57-103 mg GAE g-1 after treatment with gamma radiation. This showed no significant effect of in vitro cytotoxicity activity before and after treatment with gamma irradiation in this study. Effective concentration (EC50) values of Khaya senegalensis plant reduced significantly (P ≤ 0.005) from 44.510 μg/ml before treatment to 24.691 μg/ml after treatment with gamma radiation, which indicate an increase of free radical scavenging activity.

  6. The thermoluminescence response of doped SiO2 optical fibres subjected to fast neutrons
    Hashim S, Bradley DA, Saripan MI, Ramli AT, Wagiran H
    Appl Radiat Isot, 2010 Apr-May;68(4-5):700-3.
    PMID: 19892557 DOI: 10.1016/j.apradiso.2009.10.027
    This paper describes a preliminary study of the thermoluminescence (TL) response of doped SiO(2) optical fibres subjected to (241)AmBe neutron irradiation. The TL materials, which comprise Al- and Ge-doped silica fibres, were exposed in close contact with the (241)AmBe source to obtain fast neutron interactions through use of measurements obtained with and without a Cd filter (the filter being made to entirely enclose the fibres). The neutron irradiations were performed for exposure times of 1-, 2-, 3-, 5- and 7-days in a neutron tank filled with water. In this study, use was also made of the Monte Carlo N-particle (MCNP) code version 5 (V5) to simulate the neutron irradiations experiment. It was found that the commercially available Ge-doped and Al-doped optical fibres show a linear dose response subjected to fast neutrons from (241)AmBe source up to seven days of irradiations. The simulation performed using MCNP5 also exhibits a similar pattern, albeit differing in sensitivity. The TL response of Ge-doped fibre is markedly greater than that of the Al-doped fibre, the total absorption cross section for Ge in both the fast and thermal neutrons region being some ten times greater than that of Al.
  7. The thermoluminescence response of doped SiO2 optical fibres subjected to alpha-particle irradiation
    Ramli AT, Bradley DA, Hashim S, Wagiran H
    Appl Radiat Isot, 2009 Mar;67(3):428-32.
    PMID: 18693114 DOI: 10.1016/j.apradiso.2008.06.034
    Ion beams are used in radiotherapy to deliver a more precise dose to the target volume while minimizing dose to the surrounding healthy tissue. For optimum dose monitoring in ion-beam therapy, it is essential to be able to measure the delivered dose with a sensitivity, spatial resolution and dynamic range that is sufficient to meet the demands of the various therapy situations. Optical fibres have been demonstrated by this group to show promising thermoluminescence properties with respect to photon, electron and proton irradiation. In particular, and also given the flexibility and small size of optical fibre cores, for example 125.0+/-0.1 microm for the Al- and Ge-doped fibres used in this study, these fibres have the potential to fulfill the above requirements. This study investigates the thermoluminescence dosimetric characteristics of variously doped SiO(2) optical fibres irradiated with alpha particles from (241)Am. Following subtraction of the gamma contribution from the above source, the thermoluminescence characteristics of variously doped SiO(2) optical fibres have been compared with that of TLD-100 rods. The irradiations were performed in a bell jar. Of related potential significance is the effective atomic number, Z(eff) of the fibre, modifying measured dose from that deposited in tissues; in the present work, a scanning electron microscope and associated energy dispersive X-ray spectroscopy facility have been used to provide evaluation of Z(eff). For Ge-doped fibres, the effective atomic numbers value was 11.4, the equivalent value for Al-doped fibres was 12.3. This paper further presents results on dose response and the glow curves obtained. The results obtained indicate there to be good potential for use of variously doped SiO(2) optical fibres in measuring ion-beam doses in radiotherapeutic applications.
  8. The thermoluminescence response of doped SiO2 optical fibres subjected to photon and electron irradiations
    Hashim S, Al-Ahbabi S, Bradley DA, Webb M, Jeynes C, Ramli AT, et al.
    Appl Radiat Isot, 2009 Mar;67(3):423-7.
    PMID: 18693024 DOI: 10.1016/j.apradiso.2008.06.030
    Modern linear accelerators, the predominant teletherapy machine in major radiotherapy centres worldwide, provide multiple electron and photon beam energies. To obtain reasonable treatment times, intense electron beam currents are achievable. In association with this capability, there is considerable demand to validate patient dose using systems of dosimetry offering characteristics that include good spatial resolution, high precision and accuracy. Present interest is in the thermoluminescence response and dosimetric utility of commercially available doped optical fibres. The important parameter for obtaining the highest TL yield during this study is to know the dopant concentration of the SiO2 fibre because during the production of the optical fibres, the dopants tend to diffuse. To achieve this aim, proton-induced X-ray emission (PIXE), which has no depth resolution but can unambiguously identify elements and analyse for trace elements with detection limits approaching microg/g, was used. For Al-doped fibres, the dopant concentration in the range 0.98-2.93 mol% have been estimated, with equivalent range for Ge-doped fibres being 0.53-0.71 mol%. In making central-axis irradiation measurements a solid water phantom was used. For 6-MV photons and electron energies in the range 6, 9 and 12 MeV, a source to surface distance of 100 cm was used, with a dose rate of 400 cGy/min for photons and electrons. The TL measurements show a linear dose-response over the delivered range of absorbed dose from 1 to 4 Gy. Fading was found to be minimal, less than 10% over five days subsequent to irradiation. The minimum detectable dose for 6-MV photons was found to be 4, 30 and 900 microGy for TLD-100 chips, Ge- and Al-doped fibres, respectively. For 6-, 9- and 12-MeV electron energies, the minimum detectable dose were in the range 3-5, 30-50 and 800-1400 microGy for TLD-100 chip, Ge-doped and Al-doped fibres, respectively.
  9. Natural radioactivity in Algerian building materials
    Amrani D, Tahtat M
    Appl Radiat Isot, 2001 Apr;54(4):687-9.
    PMID: 11225705
    Samples of natural and manufactured building materials collected from Algiers have been analysed for 226Ra, 232Th and 40K using a high-resolution HPGe gamma-spectrometry system. The specific concentrations for 226Ra, 232Th and 40K, from the selected building materials, ranged from (12-65 Bq kg(-1)), (7-51 B qkg(-1)) and (36-675 Bq kg(-1)), respectively. The measured activity concentrations for these natural radionuclides were compared with the reported data of other countries and with the world average activity of soil. Radium-equivalent activities were calculated for the measured samples to assess the radiation hazards arising from using those materials in the construction of dwellings. All building materials showed Ra(eq) activities lower than the limit set in the OECD report (370 Bq kg(-1)), equivalent to external gamma-dose of 1.5 mSv yr(-1).
  10. Evaluation of production cross-sections for theranostic 67Cu radionuclide via proton-induced nuclear reaction on 68Zn target
    Ali SKI, Khandaker MU, Al-Mugren KS, Latif SA, Bradley DA, Okhunov AA, et al.
    Appl Radiat Isot, 2021 Jul;173:109735.
    PMID: 33915407 DOI: 10.1016/j.apradiso.2021.109735
    Copper-67 (T1/2 = 61.83 h, Eβ-mean=141 keV, Iβ-total=100%; Eγ = 184.577 keV, Iγ = 48.7%) is a promising radionuclide for theranostic applications especially in radio immunotherapy. However, one of the main drawbacks for its application is related to its limited availability. Various nuclear reaction routes investigated in the last years can result in 67Cu production, although the use of proton beams is the method of choice taken into account in this work. The goal of this work is a revision of the cross-sections aimed at 67Cu yield, which were evaluated for the 68Zn(p,2p)67Cu reaction route up to 80 MeV proton energy. A well-defined statistical procedure, i.e., the Simultaneous Evaluation on KALMAN (SOK), combined with the least-squares concept, was used to obtain the evaluated data together with the covariance matrix. The obtained evaluated data were also compared to predictions provided by the nuclear reaction model codes TALYS and EMPIRE, and a partial agreement among them has been found. These data may be useful for both existing and potential applications in nuclear medicine, to achieve an improvement and validation of the various nuclear reaction models, and may also find applications in other fields (e.g., activation analysis and thin layer activation).
  11. Studies of thermoluminescence kinetic parameters of polymer pencil lead graphite under photon exposures
    Khandaker MU, Mat Nawi SN, Bradley DA, Lam SE, Abdul Sani SF, Sulieman A
    Appl Radiat Isot, 2021 Aug;174:109757.
    PMID: 33990033 DOI: 10.1016/j.apradiso.2021.109757
    This study analysed thermoluminescence (TL) glow curves of the polymer pencil lead graphite (PPLG) due to its potential applications in radiation dosimetry. The TL glow curves provide information on the physical parameters of the defects participating in luminescence process. The glow curves for different diameters PPLG samples were obtained with varying temperature from 50 to 300 °C, at a fixed heating rate of 10 °Cs-1. A number of methods (initial rise, peak shape and curve fitting) were used to fit the TL glow peaks of the PPLG samples obtained under photon dose of 200 Gy. From the fitted TL signals, the trap parameters such as the order of kinetics, the activation energy, the frequency factor, etc. for the individual peaks were numerically determined. The lifetimes of TL process were calculated assuming the first-order kinetics. The results are compared among the different methods adopted in this study. Implications about the possible results in glow curve deconvolution are discussed.
  12. Industrial radiotracer application in flow rate measurement and flowmeter calibration using 99mTc and 198Au nanoparticles radioisotope
    Mohd Yunos MAS, Hussain SA, Sipaun SM
    Appl Radiat Isot, 2019 Jan;143:24-28.
    PMID: 30368049 DOI: 10.1016/j.apradiso.2018.10.008
    The flow rate or fluid velocity measurement is important to maintain fluid flow quality performance in the systems. This study focuses on determination of volumetric flow rate measurement and to calibrate the conventional flowmeter using industrial radiotracer approach in quadrilateral gas-liquid bubble column reactor. In this work, two different radioisotopes which emit γ-ray have been chosen as radioactive tracer which is 99mTc produced from 99Mo/99mTc radioisotope generator and 198Au nanoparticle form neutron activation at research nuclear reactor TRIGA Mark II. Both radioisotopes representing liquid and solid tracer purposely designed for tracing liquid flow. The peak to peak radiotracer method known as pulse velocity method was applied to determine the volumetric flow rate. The radiation signals were monitored using 4 unit NaI scintillation detectors located at 4 different points nearby the inlet and outlet of the quadrilateral bubble column reactor process stream. The water volume inside the bubble column reactor was fixed at 0.04 m3 and liquid flow rates in this reactor were specified on installed flowmeter at different reference value which is 4 lpm, 8 lpm, and 12 lpm, respectively. The experimental result shows very good linearity and repeatability by following the theoretical equations with less uncertainty in volumetric flow rate measurement. The obtained results also validated the effectiveness of the proposed method for the installed flowmeter calibration efficiency.
  13. Isodose mapping of terrestrial gamma radiation in Sarawak-Borneo: Insights from surface-weathered soil analysis
    Idris HN, Sanusi MSM, Ramli AT, Solleh MRM, Yahaya F, Ya'cob MZ, et al.
    Appl Radiat Isot, 2024 Apr 16;209:111327.
    PMID: 38642443 DOI: 10.1016/j.apradiso.2024.111327
    Presentation of baseline data on terrestrial gamma radiation (TGR) levels is crucial for assessing the annual effective dose received by the public due to natural radiation exposure. Cumulative doses from various sources can become significant, warranting a spatial understanding of TGR distribution. Few countries have comprehensively mapped TGR on a national scale, often facing challenges due to remote or inaccessible regions. This study investigated the influence of weathered soil groups on TGR dose rates in Sarawak-Borneo, Malaysia, to facilitate insights for TGR projection and isodose mapping. A total of 1044 TGR dose rate measurements were collected using NaI (Tl) scintillation detector survey meters, with a mean of 100 nGy h-1 and a range of 8-375 nGy h-1. Non-parametric statistical analyses of variance using Welch's ANOVA, Brown-Forsythe, and Kruskal-Wallis validated (P-sig.=.000) notable dissimilarities among six categories of superficial-weathered soil. Graphical analysis using Sinclair's cumulative plot revealed deviations at intervals of 50, 80, 100, 120, 175, and 205 nGy h-1. These deviations indicate distinct lithological influences. Skeletal soil (entisols) and podzolic soils had high mean dose rates (148 and 113 nGy h-1, respectively) due to limited development, thus preserving abundant uranium (U) and thorium (Th). Meanwhile, gleysols and thionic soils exhibited compatible means (90 and 82 nGy h-1, respectively), while alluvial (or transported soils) and organic soils displayed lower dose rate ranges (mean of 76 and 47 nGy h-1, respectively), reflecting rapid hydrolysis weathering processes. Simple linear regression analysis revealed a strong relationship between TGR dose rate and mean value of weathered soil groups (y = 0.851x + 0.141 nGy h-1), signifying the significance and magnitude of weathered soil groups' impact on TGR dose rates. The obtained R-value is 0.704, indicating a strong linear correlation among soil group variables, and a Durbin-Watson statistic of 1.41, suggesting positive autocorrelation among residuals, thus positive relationships. An isodose map was successfully developed using the Kriging technique, aligning with lithological features of the study area. Semivariogram analysis reveals spatial dependence within a range of 1.47°, supporting the Kriging technique's suitability for spatial inference. In conclusion, this study has successfully revealed the relationship between TGR dose rates and superficial-weathered soil in Sarawak-Borneo. While the linear relationship is applicable to the Sundaland-Borneo tectonic block, it has potential to be used as a valuable tool for spatial inference of TGR dose rates in isodose development with similar lithologial characteristics, aiding in radiation exposure assessment and environmental monitoring.
  14. Acceleration analysis of repetitive multi-MeV ion beams from pulsed plasmas
    Roshan MV, Roshan NV, Singh A
    Appl Radiat Isot, 2023 Apr;194:110706.
    PMID: 36738596 DOI: 10.1016/j.apradiso.2023.110706
    Multi-MeV ion spectra reproduced with absolute spectral index agrees with the experimental data and meet the needs to critically analyze the repetitive pulsed plasma mode of applications. The ion acceleration parameter, (Ip.rp), predicts mean ion energy and that is related to the electric discharge components based upon the precision measurements. Proper selection of repetition rate offers a relatively stable proton beam to acquire the survival curves of irradiated targets. DSB rate for plasma focus operated at 1Hz, is 10DSB/s with corresponding surviving probability of the order of 10-5. The surviving fraction is likely to be more affected by higher dose frequencies.
  15. Analysis of film response to electron beams using a laser scanner system developed in the laboratory
    San YT, Kandaiya S, Sing CL
    Appl Radiat Isot, 2005 Oct;63(4):437-42.
    PMID: 16051493
    An optical scanner system, which incorporates a He-Ne laser, photodiode detectors, and a platform for placing film, was built in the laboratory. The laser system operates at the green wavelength of 543.5 nm and functions as a scanning densitometer for measurement of optical changes in a film resulting from irradiation . The central axis electron depth dose of selected electron energies 10,12 and 14 MeV were analysed using Kodak X-Omat and Kodak Extended Dose Range (EDR2) films. The Kodak X-Omat film is routinely used for high-energy electron dose distributions in radiation therapy. The electron depth-dose measured with X-Omat film was found to agree well with standard depth-dose curves in water, obtained using an ion chamber. Conversely, the recently introduced Kodak EDR2 showed an energy dependence for electron beams, the percentage depth-dose curve shifting towards the surface for 12 and 14 MeV electron beams compared to that in water.
  16. A study of Rhizophora spp wood phantom for dosimetric purposes using high-energy photon and electron beams
    Banjade DP, Tajuddin AA, Shukri A
    Appl Radiat Isot, 2001 Sep;55(3):297-302.
    PMID: 11515650
    Previous scattering and depth-dose investigations involving use of the Malaysian hardwood Rhizophora spp have shown this medium to produce good agreement with measurements made in water. Present study extends the comparison, now including measurements of percentage depth-dose made for photons at 6MV and 5 and 12MeV electron beams. For the 6 MV photon and 5 MeV electron beams, discrepancies between percentage depth-dose for Rhizophora spp and water, at all depths, are found to be within 2.6 and 2.4% respectively. At 12 MeV electron energies, measured percentage depth-doses in Rhizophora spp beyond 3.5cm depth are found to be in significant discord with those for water. The absorbed dose in water measured in Rhizophora spp at d(max) for all three beams produces discrepancies of no more than 1.1% when compared with measurements made in water.
  17. Determination of absorbed dose for photon and electron beams from a linear accelerator by comparing various protocols on different phantoms
    Banjade DP, Tajuddin AA, Shukri A
    Appl Radiat Isot, 2001 Aug;55(2):235-43.
    PMID: 11393765
    Protocols developed for high-energy dosimetry IAEA (Technical Reports Series No. 277, 1997), AAPM (Med. Phys. 10 (1983) 741: Med. Phys. 18 (1991) 73: Med. Phys. 21 (1994) 1251), IPEMB (Phys. Med. Biol. 41 (1996) 2557), and HPA (Phys. Med. Biol. 28 (1983) 1097) have continued to enhance precision in dose measurements and the optimization of radiotherapy procedures. While recent dosimetry protocols, including those due to the IAEA and IPEMB, have made a number of improvements compared with previous protocols, it is further desirable to develop absolute dosimetry methods of dose measurements. Measurements based on careful implementation of procedures contained within the various protocols have been carried out in an effort to determine the extent to which discrepancies exist among the protocols. Dose in water at dmax was measured using cylindrical and parallel-plate ionization chambers for 6 MV photon beams and 5 and 12 MeV electron beams. Results obtained from the use of the AAPM and HPA protocols for 6 MV photon beams were found to be 0.9% larger and 0.1% smaller, respectively, than those measured following the IAEA protocol. Calibration dose measurements for 5 and 12 MeV electron beams in water phantoms were found to agree to within 1%, this being well within recommendations from the ICRU and other sources regarding the accuracy of dose delivery.
  18. Spatial distributions of (137)Cs and (239+240)Pu in surface seawater within the Exclusive Economic Zone of East Coast Peninsular Malaysia
    Ahmad Z, Mei-Wo Y, Abu Bakar AS, Shahar H
    Appl Radiat Isot, 2010 Sep;68(9):1839-45.
    PMID: 20430636 DOI: 10.1016/j.apradiso.2010.04.012
    The studies of (137)Cs and (239+240)Pu distributions in surface seawater at South China Sea within the Exclusive Economic Zone (EEZ) of Peninsular Malaysia were carried out in June 2008. The analysis results will serve as additional information to the expanded baseline data for Malaysia's marine environment. Thirty locations from extended study area were identified in the EEZ from which large volumes of surface seawater samples were collected. Different co-precipitation techniques were employed to concentrate cesium and plutonium separately. A known amount of (134)Cs and (242)Pu tracers were used as yield determinant. The precipitate slurry was collected and oven dried at 60(o)C for 1-2 days. Cesium precipitate was fine-ground and counted using gamma-ray spectrometry system at 661.62keV, while plutonium was separated from other radionuclides using anion exchange, electrodeposited and counted using alpha spectrometry. The activity concentrations of (137)Cs and (239+240)Pu were in the range of 3.40-5.89Bq/m(3) and 2.3-7.9mBq/m(3), respectively. The (239+240)Pu/(137)Cs ratios indicate that there are no new inputs of these radionuclides into the area.
  19. Radiological impacts of the amang processing industry on neighbouring residents
    Ismail B, Redzuwan Y, Chua RS, Shafiee W
    Appl Radiat Isot, 2001 Mar;54(3):393-7.
    PMID: 11214872
    The processing of amang (one of a number of tin-tailing products) for its valuable minerals has associated with the radiological and environmental problems. The processing and stockpiling of amang and ilmenite in open-air spaces, subject as it is to environmental influences, gives rise to a potential for affecting residents in adjacent area. A case study was carried out in a residential area neighbouring a typical amang plant to investigate the radiological impact to the residents. The average Effective Dose rates, calculated based on the contributions of Effective Dose rates from inhaled suspended radioactive dust, radon-thoron and their progeny, and external gamma radiation, were determined for selected houses. Results show that the occupants of those houses received Effective Dose rate, which cannot be differentiated from background. The major contributor to the average Effective Dose rate came from external radiation sources. Inhaled radon and its progeny was the second major contributor.
  20. Fulltext Results of plasma radiative compression investigation in the PF-24 device operated with D2, Ar and (100%-x)D2+x%Ar mixtures obtained using the 5-phase Lee model code
    Marciniak Ł, Akel M, Kulińska A, Lee S, Scholz M, Saw SH
    Appl Radiat Isot, 2022 Jan 21;182:110118.
    PMID: 35091151 DOI: 10.1016/j.apradiso.2022.110118
    The article presents new results for plasma radiative compression in high-current discharges in the z-pinch configuration. The results are based on the 113 discharges performed in the plasma-focus PF-24 device operated with D2, Ar and (100%-x)D2+xAr mixtures, with Ar pressure fractions x ≈ 3-60% (mole fractions). The constant initial total pressure is about 2.9 mbar and the constant initial pressure of Ar is 1.2 mbar. Each experimental discharge was simulated individually using the 5-phase Lee model code to carry out the fitting procedure of the total discharge current waveform. The results from these 113 computed discharges fitted to the corresponding 113 experimental discharges show that the increase of the effective atomic number of the gas mixture increases the probability of occurrence of plasma radiative compression phenomenon. Relatively weak radiative compression was found for part of the discharges in 15-60% range of Ar mole fractions and in Ar, while the stronger radiative compression occurred for part of discharges in Ar only. This is because there was too little total x-ray line radiation emission during the equilibrium pinch lifetime related to the very small amount of swept up mass and the low current flow through pinched plasma, represented by the decreasing values of model parameters as the Ar mole fraction increases. The results show that the main pinch parameters influencing the occurrence and strength of radiative compression are: total x-ray line emission yield, effective atomic number, initial pinch radius, initial pinch ion number density and initial pinch ion/electron temperature.
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