Determination of indoor doses and excess lifetime cancer risks caused by building materials containing natural radionuclides in Malaysia

Background radioactivity level estimation and passive shield optimization using adjoint Monte Carlo method

The current study proposes a procedure to estimate the activity concentration of natural radionuclides and to optimize passive shielding solutions for HPGe detectors using adjoint Monte Carlo (MC) simulation technique of Geant4 for the first time. The background spectrum is acquired for 1.56 × 106 s using an HPGe detector model (GC3020), set inside a shielding solution, during 2021-2022 to estimate the activity concentration of natural radionuclides inside the shielding. While, a background spectrum for 65,000 s is acquired with shielding removed to estimate the concentration of natural radionuclides in the building materials of the laboratory. The detector design used in the simulations is validated by comparing computed and measured Full Energy Peak Efficiency (FEPE) for point sources 241Am, 152Eu, 137Cs, 133Ba, and 60Co. Adjoint MC simulations are used to compute the activity concentration of natural radionuclides assuming an isotropic distribution. The activity concentration of 40K, 226Ra and 232Th in the building material is found to be 524 ± 140, 83 ± 20 and 65 ± 18 Bqkg-1, respectively. The computed values are found in good agreement with the published data. The natural radioactivity levels of 40K, 226Ra and 232Th measured in lead shielding are 155.7 ± 0.1 mBqkg-1, 24 ± 13 mBqkg-1 and 33 ± 17 mBqkg-1 respectively. The radiological risks arising due to natural radioactivity is assessed by calculating radium equivalent activity (Raeq), indoor radiation hazard index (Hin) and annual effective dose equivalent. All the radiological parameters are found below their permissible limits and building materials may be considered radiologically safe. The optimal lead shield thickness for the detector is determined to be 12 cm, resulting in reduction of background signal by two orders of magnitude compared to an unshielded detector. The adjoint MC simulations in Geant4 are 103-104 times more rapid as compared to normal simulations for shield optimization of HPGe detectors and therefore, are identified as viable computing solution to calculate the activity of the background radiation.

Investigation of natural and artificial radioactivity levels in travertines of the Cappadocia region in Turkey

This study determined natural and artificial radionuclide concentrations to evaluate natural radioactivity and health risk levels of nine travertines in the Yaprakhisar and Balkayası regions in Turkey. The samples coded B1-M, B2, B5, B7, B8, and B10 represent waste derived from the Yaprakhisar travertines, as well as samples T5-M, T12, and Z1 travertines derived from Balkayası. The levels of natural and artificial radionuclide concentrations (232Th, 40K, and 137Cs) were measured using a high-purity germanium (HpGe) detector system. The travertine activity ranged from 2.09 to 12.07 Bq kg-1 for 232Th, 4.21 to 13.41 Bq kg-1 for 40K, and 0.42-3.26 Bq kg-1 for 137Cs. The results showed that the activity concentration values for 232Th, 40K, and 137Cs were coherent with the travertine analysis results in the UNSCEAR, 2000; 2008 publications. The values obtained were lower than the average values in the UNSEAR reports. The radiological hazard parameters calculated in this study were absorbed gamma dose rate (D), radium equivalent activity (Raeq), annual gonadal dose equivalent (AGDE), exposure dose (ER), total annual effective dose (AEDEtotal), excess lifetime cancer risk (ELCRtotal), gamma representative level (GRL), internal hazard index (Hin) and external hazard index (Hex).

Geochemical characteristics, hazards impact assessment and radiogenic heat production of the alkaline rocks

This study primarily investigates the natural radioactivity level in alkaline rocks collected from the Wadi El-Dib ring complex (WDRC) in North Eastern Desert of Egypt, and assesses potential health risks associated with their use as decorative building materials. The work was accomplished using a high-purity germanium detector as well as ICP-MS and ICP-AES techniques. The WDRC composed essentially of trachyte, quartz syenite, granite and syenite. Geochemically, these rocks contain high SiO2 and alkalis with metaluminous to slightly peraluminous features. All rocks contain high concentrations of rare earth elements (∑REEs = 109-1075 ppm), with clear enrichment in light REEs compared to heavy REEs [(La/Yb)N = 8.3-25.3. Radiometrically, the concentrations of the natural radioisotopes (238U, 232Th, and 40K) in the studied rock types surpassed the worldwide average values assigned for building materials by UNSCEAR. This elevation of the radioisotope concentration values is due to the presence of supplement minerals such as monazite, zircon, allanite, and rutile. Granites exhibit the highest mean concentrations of 238U (av. 164.24 ± 14.76 Bq/kg) and 232Th (av. 214.37 ± 23.33 Bq/kg), while trachytes demonstrate the highest 40K (av. 1352.56 ± 65.56 Bq/kg) concentrations. In contrast, syenites exhibite the lowest mean concentrations for 238U (av. 54.51 ± 6.81 Bq/kg) and 232Th (av. 56.76 ± 6.25 Bq/kg), while quartz syenites display the lowest mean concentration of 40K (av. 1144.78 ± 96.19 Bq/kg). The radiogenic heat production (RHP) associated with U, Th, and K range between 1.41 to 9.33 μW/m3, exceeding the typical crustal mean value of 0.8 to 1.2 μW/m3. The radiological parameters and indices evaluating risks of the outdoor and indoor radiation doses due to the investigated rocks were assessed. The results indicated that these rocks meet globally accepted values and safety standards (approved by UNSCEAR, ICRP, and EC) for surface building materials, as well as they underscore the importance of adhering to safety protocols to safeguard workers from radiation exposure within the WDRC area. Ultimately, the data herein provide a valuable database for assessing the compatibility of geochemical data and natural radioactivity level in WDRC rocks. Additionally, it reveals that from the radiological perspective, the investigated rocks are considered safe for use as decorative construction materials.

Assessment of radioactivity in sand samples from eastern Nepal in perspective of radiological hazards

This study was conducted to investigate the activity concentrations of 226Ra, 232Th and 40K in the sand samples and the health hazards associated with them utilizing a NaI (Tl) gamma spectrometer. The average activity concentrations of 226Ra, 232Th and 40K were found to be 24.8 ± 10.1, 39.8 ± 16.4 and 531.3 ± 52.8 Bq kg-1, respectively. The calculated radiological hazard parameters, including radium equivalent activity, absorbed gamma dose and effective dose rate, were found to be 122.7 ± 34.0 Bq kg-1, 57.7 ± 14.9 nGy h-1 and 0.3 ± 0.1 mSv y-1, respectively. Notably, these results were observed to be below the recommended thresholds. Other measured hazard indices were also lower than the prescribed values. From a radiological perspective, the present study concludes that the sand samples do not pose any threat to human health when utilized as a building material.

Radiological risk assessment of beaches from volcanic oceanic islands: A case study of the Eastern Canary Islands (Spain)

This work constitutes the first survey that allows the establishment of baseline levels of environmental radioactivity in beach sands from the volcanic oceanic islands of La Graciosa, Lanzarote, Fuerteventura and Gran Canaria. Activity concentration values of 226Ra, 232Th and 40K were measured by gamma spectroscopy in 108 samples, collected from 39 beaches across the whole study region. The radiological hazard risks associated with these sands were studied. The mean absorbed dose rate in the study region was 20 nGy h-1, which is below the world average value. The mean outdoor annual effective dose for the beaches studied was 0.025 mSv y-1, which is within the internationally accepted safe limit. Additionally, the assessment of the radium equivalent showed that all samples from the Eastern Canary Islands are below the safe limit of 370 Bq kg-1. Despite not posing any radiological risk to the human population, the radiological hazard indices obtained in Gran Canaria were significantly higher than those of other islands. These significant differences seem to be related to the presence of sediments in the beaches of Gran Canaria that have their origin in lithologies with higher activity concentration values of 226Ra, 232Th and 40K that are not present in the rest of the islands.

Evaluation of potential radiological hazards of unfired construction materials containing fly ash in Vietnam

In this study, the specific activities of 226Ra, 232Th and 40K in the unfired construction materials (solid card bricks, 4-hole bricks, pavement bricks) containing fly ash and bottom ash from a coal-fired thermal power plant in Vietnam were measured using the low-level gamma-ray spectrometer with HPGe detector. Also, the 222Rn concentrations in these materials were analyzed using RAD7 radon monitor and then radon mass exhalation rate and emanation fraction of these materials were calculated. The potential radiological hazards for residents living in the model room made of these materials were evaluated. The average specific activity of 226Ra, 232Th and 40K were found as 67.7, 79.3 and 703.5 Bq kg-1, respectively. The total annual effective dose (due to external gamma exposure and internal radon exposure for resident living in the CEN model room made of the unfired brick samples) was found as 0.9 mSv y-1 which is lower than the worldwide average dose of 2.4 mSv y-1. Calculations from ResRad-Build code showed that the doses due to radon exposure account for from 62.3% (at the first year) to 98.8% (at the next 30 years) of the total gamma and radon dose. Under low air exchange to the outside environment, from the 6th year onwards, the total dose may exceed the average dose value from natural radiation exposure sources.

Radiological hazard assessment of natural radioactivity in Avcilar region, Turkey: a case of Istanbul University-Cerrahpasa Avcilar Campus

Radionuclides 226Ra, 232Th, and 40K can be found in various concentrations in the surface soil. High concentrations of radionuclides in the surface soil may cause radiological risks. This study investigated natural radioactivity levels and artificial radionuclide (137Cs) levels in the Istanbul University-Cerrahpasa, Avcilar region, Istanbul, Turkey. Radioactivity concentrations were analyzed using the gamma-ray spectrometer. The mean activity concentration of 226Ra, 232Th, 40K, and 137Cs is 28.55, 29.57, 385.72, and 3.09 Bq kg-1, respectively. Radiological parameters radium equivalent activity, absorbed dose rate, annual effective dose equivalent, external hazard index, and excess lifetime cancer risk were calculated using activity concentrations. The radiological parameters values were lower than UNSCEAR values, except for the annual gonadal dose equivalent (approximately 10% higher). There is a strong correlation between radiological parameters and radionuclides. Generally, the activities of radionuclides in the region fall within the recommended limits, thus Istanbul-Avcilar region can be considered safe for settlement.

Distribution of natural radionuclides in NORM samples from North Abu Rusheid area, Egypt

The North Abu Rusheid area in Egypt is a well-known high background natural radiation area (HBNRA) due to the existence of naturally occurring radioactive materials (NORMs) in mylonitic rocks. In this study, 27 rock samples were selected for dose estimation studies. ²³⁸U and ²³²Th were measured using inductively coupled plasma mass spectrometry (ICP-MS) and ⁴⁰K was measured using sodium iodide (thallium) gamma-ray spectroscopy. The ranges of activity concentrations (Bq/kg) of ²³⁸U, ²³²Th and ⁴⁰K in the samples varied from 270 ± 2 to 2120 ± 29, 350 ± 2 to 1840 ± 27 and 20 ± 2 to 1390 ± 35 with mean values of 980 ± 349, 770 ± 351, and 640 ± 402 Bq/kg, respectively. The radiological hazard parameters were estimated from activity concentrations of ²³⁸U, ²³²Th and ⁴⁰K and compared to United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR) values. The present study revealed that the hazard parameters were several times higher than the worldwide averages. The U/Th concentration ratio ranged from 0.7 to 3 and could be attributed to the presence of kasolite, uranothorite, zircon, and columbite in mylonitic rocks. From the radiological protection viewpoint, it is necessary to monitor natural radionuclides in these rocks prior to their use in residential and commercial construction materials.

A window into the future: case study of long-term radiological risk modelling posed by unregulated mining waste repurposing activities

The study aims to assess long-term radiological exposure risks and effects to both industrial workers and occupants living in the near vicinity of local tailing processing plants. The detrimental effects of licensing exemption were studied by comparing contaminated soil collected from 7 unlicensed-by the Atomic Energy Licensing Board-tailing processing plants with soil from control location. It was found that the average concentration of ²²⁶Ra, ²³²Th, and ⁴⁰ K for all seven processing plants fell between the range of 0.1 ± 0.0-7.21 ± 0.1 Bqg^-1, 0.1 ± 0.0-16.34 ± 0.27 Bqg^-1, and 0.18 ± 0.01-1.74 ± 0.01 Bqg^-1, respectively, showing observable indication of soil contamination with Technologically Enhanced Naturally Occurring Radioactive (TENORM) material. The annual effective dose was calculated which showed that most samples exceeded the recommended value of the ICRP of 1 mSvy^-1 for non-radiation workers. Assessment of radiological hazards in the environment was done by calculating the radium equivalent value; revealing the exposure risk posed by the contaminated soil is substantial. Using the relatable inputs, the RESRAD-ONSITE computed code revealed that the dose due to internal exposure via inhalation of radon gas contributes the most to the overall exposure. The covering of the contaminated soil with a clean layer is effective in reducing external dose but ineffective for radon inhalation. RESRAD-OFFSITE computer code also revealed that the contribution of exposure via contaminated soil in the neighbouring vicinity is below the recommended 1 mSvy^-1 threshold but still contributes to a significant amount cumulatively when considering other exposure pathways as well. The study proposes the introduction of clean cover soil as a viable option in reducing external dose from contaminated soil as 1 m of clean cover soil is able to reduce dose exposure by 23.8-30.5%.

Radiological assessment of the disposal of bulk oil NORM waste: Case study from Brazil

The oil and gas industries are the largest producers of NORM wastes that are continuously generated during production and extraction activities. In addition, an increasing trend is observed in waste production worldwide due to the decommissioning of oil platforms. The problem is that most of these wastes are in activity concentration levels above the exemption and the clearance limits and are being accumulated in storage sites because no repositories exist in Brazil for NORM wastes generated by oil industries. There are regulations for radioactive wastes and for the licensing of repositories for managing wastes with low and intermediate levels of radiation but the current regulations apply only to packaged wastes. Therefore an initial radiological assessment was carried out with the RESRAD-OFFSITE code to show that bulk NORM wastes (not packaged wastes) could be disposed of in repositories near the surface without causing additional risk to the public above the criteria used. The results can also support decision-making by the Regulatory Authority to change the current regulations and allow for the disposal of wastes in bulk form.

Micro-mapping of terrestrial gamma radiation dose rate in typical urban homes in Miri City (Sarawak, Malaysia)

Micro-mapping of terrestrial gamma radiation dose (TGRD) at meter grid spacing in and around four urban homes in Miri City shows rates ranging from 70 to 150 nGy/h. Tiled surfaces (floors and walls) vary between properties and have a clear and significant influence on TGRD which is highest in kitchens, washrooms and toilets. Application of a single indoor value for annual effective dose (AED) may lead to underestimations of up to 30%. The AED is unlikely to exceed 0.8 mSv in homes of this type in Miri, which is within recommended guidelines.

DETERMINATION OF RADIOACTIVITY LEVELS IN BLACK AND WHITE SANDS USED FOR BUILDINGS AND ESTIMATION OF RADIATION HAZARDS IN THE NORTH-WEST REGION OF ETHIOPIA

One hundred and two black and white sand samples were compiled from disparate sand excavates from the affluent rivers of Lake Tana. The supreme values of 226Ra, 232Th and 40K were calculated in Bq Kg-1 units from black sand samples, while the undermost deals were found from pieces of white sand. The potential radiological health parameters were sized up by determining the radium equivalent progressively activity (Raeq), outdoor immersed gamma potion rate (Dout), annual effective potion rate, internal hazard (Hin) and external hazard (Hex) indices and gamma index from using those sands in the erection of dwellings and large buildings. The outcomes acquired show that the annual potion immersed by occupants due to sand construction use in the north-west region of Ethiopia is <1.0 mSv y-1, while the outdoor absorbed dose rate, gamma index and internal hazard index are higher than the quoted values of 55 nG h-1, 1 and 1, respectively.

Natural radioactivity and radiological risk assessment due to building materials commonly used in Erbil city, Kurdistan region, Iraq

Radiometric monitoring of construction materials is required for estimating the interior and exterior exposure to ionizing radiation emitted by terrestrial radioactive elements in building materials. Using gamma-ray spectroscopy, the activity concentrations of ²²⁶Ra, ²³²Th, and ⁴⁰ K in fifty-two samples from eighteen different building materials commonly used in Erbil city, Kurdistan region, Iraq, were evaluated to assess possible radioactive dangers to human health. The activity concentrations of ²²⁶Ra, ²³²Th and ⁴⁰ K ranged from 1 ± 0.1 (gypsum board) to 130 ± 11 (granite), 1.3 ± 0.2 (gypsum) to 66 ± 8 (ceramic sample), and 18.74 ± 4 (gypsum) to 1061.708 ± 40 (granite) with an average of 28 ± 5, 20.7 ± 4, and 340.8 ± 18 (average ± standard deviation), respectively. Radiological indicators (activity concentration index, alpha and gamma index, hazard indices, interior absorbed gamma dose rate and the corresponding yearly effective dosage rate, and excess lifetime cancer risk) were computed to assess the health risks associated with these building materials. Consideration was given to the indoor annual effective dosage for common construction materials, the radon surface expiration rate, and the indoor radon concentration. The mean values of activity concentration were then inputted into the RESRAD-BUILD computer software to calculate a resident's long-term radiation exposure. The dosages were measured over a range of 0 to 70 years. From 0 to 30 years, there was a significant change in dosages; however, from 30 to 70 years, the dosages were reasonably consistent. This research demonstrates that granite samples are not safe for dwellings with poor ventilation (especially those without windows). In general, other investigated construction materials in the buildings are deemed safe for the population, since the computed values for these parameters fall within the well-being restrictions or criterion values.

Modification of Clinoptilolite as a Robust Adsorbent for Highly-Efficient Removal of Thorium (IV) from Aqueous Solutions

The natural zeolite has been modified with sulphate and phosphate. The adsorption of thorium from the aqueous solutions by using the natural and modified zeolites has been investigated via a batch method. The adsorbent samples were characterized by X-ray Diffraction (XRD), N₂ adsorption-desorption (BET), Fourier transform infrared (FTIR), field emission scanning electron microscopy (FESEM), and energy dispersive X-ray spectroscopy (EDX). Modification of natural zeolite with sulphate and phosphate was found to increase its adsorption capacity of thorium but reduced its specific surface area (S_BET). The adsorption experiments were expressed by Langmuir, Freundlich and Dubinin-Radushkevitch (D-R) isotherm models and the results of adsorption demonstrated that the adsorption of thorium onto the natural and modified zeolites correlated better with the Langmuir isotherm model than with the Freundlich isotherm model. The maximum adsorption capacity (Qo) was determined using the Langmuir isotherm model at 25 °C and was found to be 17.27, 13.83, and 10.21 mg/g for phosphate-modified zeolite, sulfate-modified zeolite, and natural zeolite, respectively. The findings of this study indicate that phosphate-modified zeolite can be utilized as an effective and low-cost adsorbent material for the removal of thorium from aqueous solutions.

Investigation of Building Materials' Radioactivity in a Historical Building-A Case Study

The paper investigates a possible hazard originating from natural radionuclides in building materials in a selected historical building being reconstructed for housing. Both outdoor and indoor risks were evaluated through the radiological indices and estimated doses, based on measured activities of natural radionuclides in stone and brick materials of the building. The average measured activity concentrations of radionuclides were 7.32 Bq/kg for ²²⁶Ra, 40.05 Bq/kg for ²³²Th, and 546.64 Bq/kg for ⁴⁰K radionuclides. The average total activity concentration in building materials (594.0 Bq/kg) exceeded the world average value. A correlation was found between the potassium content in the building material samples and the total activity of radionuclides. The gamma indices, Iγ, calculated for the samples, ranged in an interval of 0.26-0.60, not exceeding the restricted limit for bulk materials Iγ = 1. The average annual effective dose due to building materials was 0.53 mSv/y, which does not exceed the limit (1 mSv/y), however, it contributes to a gamma dose excess that is higher than recommended (0.3 mSv/y at the most). The bricks were responsible for a higher level of natural radiation than natural stone material. Nevertheless, based on the radiation protection requirements, it can be concluded that the building can be used for residential purposes after the reconstruction, as no significant human health impact is expected due to the radioactivity of building materials.

Evaluation of natural radioactivity levels and potential radiological hazards of common building materials utilized in Mediterranean region, Turkey

Radiometric measurement of building materials is very important to assess the internal and external exposure caused by the ionizing radiation emitted from terrestrial radionuclides in building materials. The activity concentrations of ²²⁶Ra, ²³²Th, and ⁴⁰K in fifty-eight samples of fifteen different structural and covering building materials commonly used in Osmaniye province located in the Mediterranean region of Turkey were measured by using gamma-ray spectroscopy. The activity concentrations of ²²⁶Ra, ²³²Th, and ⁴⁰K varied from 2.5 ± 0.1 (marble) to 145.7 ± 4.4 (clay brick), 1.3 ± 0.1 (marble) to 154.3 ± 4.1 (marble), and 8.6 ± 0.2 (sand) to 1044.1 ± 70.3 (granite), respectively. Radiological parameters (activity concentration index, alpha index, indoor absorbed gamma dose rate and the corresponding annual effective dose rate, and excess lifetime cancer risk) were estimated to evaluate the health hazards associated with these building materials. Since the estimated values of these parameters are within the recommended safety limits or criteria values, the use of the studied building materials in the construction of dwellings can be considered to be safe for the residents of the region.

Health Hazards Assessment and Geochemistry of ElSibai-Abu ElTiyur Granites, Central Eastern Desert, Egypt

In this paper, a thorough radio- and chem-ecological evaluation of ElSibai-Abu ElTiyur granites located within Egypt’s crystalline basement rocks was conducted for risk and dose assessments. Twenty granitic samples from the study area’s various lithological units were analyzed using high-resolution γ-ray spectrometry to determine the natural radioisotopes (U-238, Th-232, and K-40) concentrations. The average concentrations of U-238, Th-232, and K-40 were 38.72, 38.23, and 860.71 Bq/kg, respectively, exceeding the GAV (global average value) documented by UNSCEAR (Scientific Committee on the Effects of Atomic Radiation, Vienna, Austria). The radiological parameters and indices judging the usage of ElSibai-Abu ElTiyur granites in homes were computed. The obtained results showed that ElSibai-Abu ElTiyur granites are safe to be used by inhabitants as superficial building materials, as per the globally accepted values and the recommended safety limits approved by UNSEAR, WHO (World Health Organization, Geneva, Switzerland), ICRP (International Commission on Radiological Protection, Ottawa, ON, Canada), and EC (European Commission, Luxembourg). Further, the samples were subjected to ICP-MS (inductively coupled plasma mass spectrometry) analysis for quantifying radionuclide variations with chemical composition. Geochemically based on the ICP-MS results, the studied granites proved to be highly evolved A-type granites. They span the metaluminous to peralkaline fields. The REE patterns are characterized by the enrichment of the light rare earths (LREE) over the heavy ones (HREE) where (La/Yb)n = 5.2, (Gd/Yb)n = 1.63 with pronounced negative Eu-anomalies (Eu/Eu*)n = 0.49. The albite granite exhibits the highest concentrations of Ga, Nb, Ta, U, and Y, and REE (Gd, Dy, Ho, Yb) than the Na-metasomatic granites. Finally, the obtained data serve as a valuable future database for finding out the compatibility of the geochemical data with the natural radioactivity levels of granites.

Assessing energy efficiency in the Asia-Pacific region and the mediating role of environmental pollution: evidence from a super-efficiency model with a weighting preference scheme

The demand for primary energy resources has increased significantly due to the rapid growth of the global economy and increasing greenhouse gas (GHG) emissions. Therefore, improving energy efficiency levels is essential for global energy, energy security, and environmental sustainability. In the context of the Asia-Pacific region, the study of energy efficiency among different countries can play a role in better energy utilization. These countries also provide a policy for the Asia-Pacific region to improve its energy utilization. This study's primary focus is to investigate the optimal efficiency score of 15 areas of the Asia-Pacific region, and the analysis is based on super-efficiency (radical) and super slacks-based measure (SBM) data in a nonparametric DEA model. Three areas in the Asia-Pacific are selected for energy efficiency measures: South Asia, East Asia, and Australasia. The results suggest that Bangladesh, Pakistan, China, Singapore, New Zealand, the Philippines, Japan, India, Indonesia, Malaysia, Thailand, and Vietnam obtain the most efficient score of 1 in both DEA models throughout the study period. Australia and Sri Lanka receive a low score during all study periods, while Hong Kong does not have data for all study years. The results of the study will help improve energy performance, cost-effectiveness, and environmental sustainability, increasing the competitiveness and scalability of efficient energy sources.

EFFECT OF WORKING CONDITIONS AND NATURAL RADIOACTIVITY LEVELS ON OCCUPATIONAL DOSES TO WORKERS OF AN OLD MANGANESE MINE

The aim of this work was to use RESRAD-Build model to predict the resulting external and internal radiological doses received by the workers of manganese mine located in Southern Sinai. In order to achieve that goal, measurement of the activity concentrations of natural radionuclides in rock samples collected from the inside gallery of such mine, using hyper pure germanium (HPGe) detector. Radon gas concentrations were also measured. The average activity concentrations of 238U, 226Ra, 232Th, 40K and 210Pb in rock samples were 207.3, 155.5, 59.7, 304.5 and 119.3 Bq kg-1, respectively. The average radon activity concentration was 1254.6 Bqm-3, which is equivalent to 0.135 WL. The radon concentration increases further as going deep inside the mine up to 6238 Bqm-3. RESRAD-Build model occupational effective dose equivalent (EDE) received by the workers, from natural radionuclides, dominated by 222Rn emanated from the parent nuclide 226Ra.There was good agreement between the occupational annual EDE calculated from the measured rock samples and that predicted by modeling, with estimated values of 83.8 and 82.1 mSvy-1, respectively. This radiological dose assessment indicated the predominance of internal pathways owing to radon decay products, in both cases (measured and modeled). The occupational radiological dose from the inhalation of radon and radon decay products resulted in a high lung cancer risk based on the current measurements and ventilation conditions within the mine.

ASSESSMENT OF NATURALLY OCCURRING RADIONUCLIDES IN MALAYSIA'S BUILDING MATERIALS

The activity concentrations of 226Ra, 232Th and 40K radionuclides from common building materials used by Malaysian people for construction purposes were studied using High-Purity Germanium (HPGe) detector. The measured activity concentrations of the aforementioned radionuclides range from 10 ± 1 Bq kg-1 (limestone) to 155 ± 61 Bq kg-1 (feldspar), 12 ± 3 Bq kg-1 (limestone) to 274 ± 8 Bq kg-1 (kaolin) and 62 ± 19 Bq kg-1 (limestone) to 1114 ± 20 Bq kg-1 (pottery stone) for 226Ra, 232Th and 40K, respectively. The measured activity concentrations of the natural radionuclides reported herein were found to be in accordance with other previous studies. In general, the activity concentration of the natural radionuclides revealed that all the determined values were below the recommended limit.