Analysis of MNSR core composition changes using the codes WIMSD-4 and CITATION.
The codes WIMSD/4 and BORGES--part of the MTR-PC code package--have been applied to prepare the microscopic cross-section library for the main elements of miniature neutron source reactor (MNSR) core for six neutron energy groups. The generated library has been utilized by the 3D code CITATION to perform the calculation of fuel burn-up including the identification of main fission products and their impacts on the multiplication factor. In this regard some modifications have been introduced to the subroutine NUCY in CITATION to incorporate estimating the concentration of the related actinides and fission products. The burn-up results have indicated that the core life-time of MNSR is being mainly estimated by Sm(149) followed by Gd(157) and Cd(113). The accumulation of these fission products during 100 continuous operation days caused a reduction of about 4.3 mk for the excess reactivity. This result seems to be in good agreement with the available empirical value of 3.5 mk, which relates to the whole discontinuous operation period of the reactor since its start up to now. The calculation procedure simulates the sporadic operation with an equivalent continuous operation period. This approximation is valid for the long-lived fission products that mainly dictate the core life-time. However, it is an overestimation for the concentration of short-lived radioactive products like Xe(135).
Haj Hassan
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Department of Nuclear Engineering, Atomic Energy Commission, P.O. Box 6091, Damascus, Syria.
Ghazi
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N
Hainoun
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D017076:Computer-Aided Design; D004867:Equipment Design; D019544:Equipment Failure Analysis; D009502:Neutrons; D009688:Nuclear Reactors; D011829:Radiation Dosage; D011874:Radiometry / Q000379:methods*; D012984:Software