Browsing by Author "Mollah, Abdus Sattar"

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Investigation on the attenuation neutron and gamma rays in reactor concrete biological shield
(Department of Physics, BUET, 1987-12) Mollah, Abdus Sattar; Ahmad, Dr. Gias uddin
The biological shield of a nuclear reactor is required to attenuate both neutrons and gamma rays from the reactor core. Generally, materials having high densities are used as bio 1ogica1 shie1d materia1s in a nuc lear reactor. Concrete has been widely used as shielding materials due to its satisfactory material strength and good shielding properties. The density of conventional ordinary concrete is not adequate for.a biologiGal shield in a nU,clear reaGtor. Types of concrete possessing high density, should be developed in order to attenuate both neutron and gamma radiation emitted from the nuclear reactor. The heavy aggregates such as barite, magnetite, ilmenite, limonite etc. have been widely used for preparing a high dens~ty concrete for-biological shield in a nuclear reactor. While fabricating the high density concretes, due consideration should be given to the local availability of the aggregates. Since the magnetite and ilmenite aggregates are available as -by products in the beach sand processing pilot plant at Cox's Bazar of the Bangladesh Atomic Energy Commission, this work was undertaken to design and fabricate high density concrete shields indigenously with the objective of avoiding costly imports and also to develop -local know how. In this study, high density concrete with and without boron additives using ilmenite and magnetite sand have been studied. For comparison, ordinary concrete with and without boron additives have also been studied. In addition, mixed conc~ete used in the biologic~l shield of 3 MW TRIGA Mark-II research reactor of the Bangladesh Atomic Energy Commission has been studied with and without bo~on additives for comparison with the other three types of concretes with and wihtout boron additives. The density, compressive strength, modulus of elasticity and splitting strength were measured for these concretes. The densities of ilmenite and magnetite concretes are found considerably higher than that of ordinary concrete. The nuclear parameters such as attenuation coefficient, removal cross section, half value thickness, and relaxation length, which are of interest for reactor shielding have been evaluated for these concretes with a spontaneous fission source (252Cf). The investigation concerning the attenuation properties reveals that the shielding properties of boron loaded heavy concretes are better than those of ordinary concretes and slightly better than those of heavy concretes without boron additives.
Potential Health Impacts from Radioactive Releases at Rooppur Nuclear Power Plant Under Hypothetical Accident Scenario
(Research and Development Wing, MIST, 2025-12-30) Mawla, Md Rosaidul; Ryean, Radmim; Rahman, Anisur; Mollah, Abdus Sattar; Islam, Md. Shafiqul; Kabir, Kazi Imtiaz
This study presents a comprehensive assessment of radiological dose consequences from potential severe accident scenarios at the Rooppur Nuclear Power Plant (NPP), focusing on health impacts from radioactive releases. Utilizing HotSpot 3.1.2 and ORIGEN 2.2, the research estimates Total Effective Dose Equivalent (TEDE) and Committed Effective Dose Equivalent (CEDE) to critical organs, including the thyroid, skin, lungs, surface bone, red marrow, and liver, under seasonal meteorological conditions. The thyroid, due to its high affinity for radioactive iodine (particularly 131I), showed maximum CEDE values of 8.0 × 105 Sv and 4.4 × 105 Sv during the autumn and rainy seasons, respectively, at 30 meters from the source. These values, along with other organ doses, exceeded public and occupational dose limits up to 15 km in the rainy season and 30 km in the autumn season, primarily influenced by wind speed and precipitation. The study underscores the need for emergency protective measures such as sheltering, evacuation, and the administration of potassium iodide (KI), especially for populations within high-risk zones. It further recommends the integration of dose modeling findings into the National Nuclear and Radiological Emergency Preparedness and Response Plan (NNREPRP) to enhance response strategies and protect public health in the event of nuclear accidents.
Review and Analysis of Environmental Impacts of Different Energy Technologies: Clean Environment From Nuclear Energy
(R&D Wing, MIST, 2017-12) Mollah, Abdus Sattar; Sattar, Sabiha; Hossain, Altab; Md. Salahuddin, Abu Zafor; Khan, Md Shohail Hossain
No form of energy production or use is without environmental impact. The principal environmental impacts associated with nuclear power and sustainable development is air pollution/green-house gas (GHG) emissions and radiation. Nuclear energy plants do not emit pollutants or greenhouse gases when they generate electricity. Nuclear power plants in normal operation emit fewer radioactivities than coal power plants. Nuclear energy has one of the lowest impacts on the environment of any energy source because it does not emit air pollutants, isolates its waste from the environment and requires a relatively small amount of land. Handling, storage and disposal of low and medium-level nuclear waste pose no serious problem. No reason to worry about the management of nuclear wastes from the Rooppur nuclear power plant. As nation’s demand for electricity grows, we must find a way to produce it without damaging our environment. Nuclear energy can help us meet this challenge-safely, cleanly, economically. This paper describes the environmental aspects of the major sources of different energy technologies.
Structural and Thermal Analysis of Fuel Rod of VVER-1200 Nuclear Reactor Using ANSYS Software
(Research and Development Wing, MIST, 2025-06) Nusrat Jahan Shanta, Shah; Mollah, Abdus Sattar
This study focuses on analyzing the thermo-mechanical behavior of fuel rods in VVER-1200 nuclear reactors to ensure their safe and efficient operation. Bangladesh plans to operate two VVER-1200 reactors at Rooppur by 2025/2026, aligning with global effortsto shift toward low-carbon energy sources. The analysis, performed using ANSYS software, evaluates key parameters such as deformation, stress, strain, temperature distribution, and heat flux. A detailed geometric model of the UO₂ fuel rod with zirconium alloy cladding and helium gas in the gaphas been developed. Thermal distribution simulations under steady-state conditions reveal critical temperature gradients, while structural analysis identifies high-stress regions due to thermal expansion and operational loads.