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UNIVERSITY OF BUCHAREST
FACULTY OF PHYSICS Guest
2024-11-22 2:06 |
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Conference: Bucharest University Faculty of Physics 2010 Meeting
Section: Applied Nuclear Physics
Title:
Study of advanced CANDU fuel radioactivity evolution with irradiation by using burnable neutron absorbers in fuel bundle centre element composition
Authors:
C. A. Margeanu (1), I. Prodea (1), G. Olteanu (1)
Affiliation:
(1) Institute for Nuclear Research Pitesti, Romania
E-mail
cristina.margeanu@yahoo.com
Keywords:
Advanced CANDU fuel, Advanced SEU fuel bundle, burnable neutron absorber, burnup, radioactivity, ORIGEN-S, WIMS
Abstract:
Atomic Energy of Canada Limited (AECL) is developing the Advanced CANDU Reactor (ACR) to meet customer requirements (industry and public expectations for safe, reliable, environmentally friendly, low-cost nuclear generation) for the emerging nuclear market over the next 20 years of sales.
The use of Slight Enriched Uranium (SEU) fuel with a neutron absorbing centre element allows the reduction of Coolant Void Reactivity (CVR) coefficient to a nominally small, negative value, as a response to an important criticism addressed to the positive CVR characterizing the present CANDU reactors. It also results in higher burnup operation than traditional CANDU designs. Burnable neutron absorbing materials are expected to be an integral part of the new fuel design for Advanced CANDU® Reactor, the studies based on using of a Zirconium alloy centre element (no fissile content) surrounded by a thin neutron absorbing material shell being successfully applied to ACR fuel project.The paper follows to study the fuel radioactivity at the end of irradiation (EOI) characterizing the ASEU fuel bundle (Advanced SEU fuel bundle with 43 elements, developed in INR Pitesti, and similar to Canadian ACR fuel bundle) by considering various centre element shell compositions and fuel burnup. The ASEU fuel bundle elements (except for the centre element) contains SEU pellets, 2.4 wt% enrichment in 235U.
In order to perform the proposed simulations the following shell compositions have been used: pure Hafnium and equal percents mixtures of burnable absorber and Zirconium oxides, the considered burnable absorbers being Gadolinium, Dysprosium, Holmium, Erbium and Hafnium (taken into account according to IAEA WIMS Libraries Update Project). To obtain a significant and broad range of results, several centre element shell thicknesses (0.5 mm, 1 mm, 2 mm and 3 mm) have been considered. The fuel burnup calculations have been performed for 8000 MWd/tU, 16000 MWd/tU and 20000 MWd/tU, respectively. Fuel elements irradiation was modeled by assuming constant power for entire irradiation period, the considered power being about 50 MW/kg U.The burnup was simulated by means of ORIGEN-S code, included in SCALE5 programs package. The spectral neutron cross-sections weighting factors used as input in ORIGEN-S data were given by WIMS-D5B multigrup transport lattice code calculations.The paper provides EOI fuel radioactivity comparisons both for different burnable absorber shell compositions and a specific centre element shell composition but with different thicknesses, by taking into account the considered fuel burnup.
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