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MCNPX Simulation of a CT System for the Bushehr Nuclear Power Plant Waste Barrels

Ahmadi Mirzahassanlou, Maryam | 2017

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 49480 (46)
  4. University: Sharif University of Technology
  5. Department: Energy Engineering
  6. Advisor(s): Samadfam, Mohammad; Movafeghi, Amir
  7. Abstract:
  8. Each year, large quantities of low/intermediate operational radioactive wastes are produced in different matrices. Usually, these wastes are temporarily stored within the plants and after a certain period, they have to be transferred to landfill sites for final disposal. According to international regulations recommended by IAEA as well as, requirements imposed by national regulatory bodies, waste packages must clear certain requirments called Waste Acceptance Criteria. As such, all waste packages are subject to certain inspections in plant or at disposal facilities. Computerized Tomography (CT) is proven to be one of the most efficient inspection tools for waste packages that can reveal defects like air gaps and cracks in waste matrices. For this purpose, a first-generation transmission CT system was simulated by MCNPX code and two different image reconstruction algorithms were employed. At first, for validation of simulation method and image reconstruction algorithms, two standard phantoms were simulated. Our simulation results showed very good agreement with the reported values; the error was less (or same at worst) than what has been reported in the literature. After this validation, a cemented waste package containing 60Co was simulated. It was assumed that the package has a cylinderical air defect of 5 cm in diameter. The image was produced by an external source 60Co and a SIRT and FBP image reconstruction methods. Due to the interference in transmission’s data, caused by the internal source, the images at lower intensities of the external source does not have the acceptable quality. It was found that the ratio of the external to internal source activities must be at least 2500 in order to reveal the air defect with an acceptable error. In general, we concluded that, under certain circumstances, the CT system with a radioisotope source have the ability to scan the radioactive waste. In addition, the used image reconstruction algorithms can reconstruct images containing objects with different densities
  9. Keywords:
  10. Radioactive Waste ; Simulation ; Image Reconstruction ; Monte Carlo N-Particle (MCNP)Code ; Computerized Tomography

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