Hamed Khodadadi; Kamyar Sabetghadam
Abstract
Probabilistic uncertainty and sensitivity analysis is frequently recommended for safety and reliability assessment of computer simulations. For this purpose, SUAP has been developed, and its latest version is capable of working on analysis results obtained using five well-known nuclear codes (i.e. FRAPCON, ...
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Probabilistic uncertainty and sensitivity analysis is frequently recommended for safety and reliability assessment of computer simulations. For this purpose, SUAP has been developed, and its latest version is capable of working on analysis results obtained using five well-known nuclear codes (i.e. FRAPCON, FRAPTRAN, FEMAXI, MCNP, and COBRA). SUAP provides support to properly quantify input uncertainties as to probability distributions and appropriate dependency functions. Using the Monte-Carlo sampling method, random combinations of different uncertain input parameters are generated and used to make input files for the corresponding code applied for the modeling. To quantify uncertainties, SUAP determines the variation range for each specific output parameter at any chosen time and/or location. Moreover, sensitivity analysis is accomplished based on the Spearman correlation. In this study, in order to evaluate SUAP applicability, UQ&SA for fuel performance modeling of VVER-1000 fuel rods using FRAPCON code has been accomplished. Acquired results exhibit the possible range of uncertainties in fuel centerline temperature, as well as the importance of different uncertain input parameters on that.
Hamed Khodadadi; Amir Zareidoost
Abstract
After some accidents like TMI and Fukushima Daiichi, the belief that nuclear fuels can safely and reliably be used up to 65 MW.d/kgU was revised. Different short to long term concepts started to be assessed more seriously. Among these concepts, Cr-coated Zr cladding tubes were taken into consideration ...
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After some accidents like TMI and Fukushima Daiichi, the belief that nuclear fuels can safely and reliably be used up to 65 MW.d/kgU was revised. Different short to long term concepts started to be assessed more seriously. Among these concepts, Cr-coated Zr cladding tubes were taken into consideration as a promising remedy for the short term perspectives. Various efforts to evaluate important aspects of such designs (including coating methodologies, full size coating of cladding tubes, performance analysis, licensing features and so on) have been implemented and some activities are yet under accomplishment. In this study, an optimized cathodic arc PVD coating condition, from the defect density point of view, for applying Cr and CrN coating layers up 10 microns on typical VVER-1000 cladding tubes (Zr-1%Nb alloy) have been obtained. SEM results approved improvements, and furthur modification has been postponed till the finalizing the performance examinations in normal operational and accidental conditions (specifically, LB LOCA condition). Additionally, the list of required test, from characterizations to mechanical and performance experiments, in order to qualify the applicability of such coated samples are suggested.
