Abstract
Fission product yields (FY) are fundamental nuclear data for several applications, including decay heat, shielding, dosimetry, burn-up calculations. To be safe and sustainable, modern and future nuclear systems require accurate knowledge on reactor parameters, with reduced margins of uncertainty. Present nuclear data libraries for FY do not provide consistent and complete uncertainty information which are limited, in many cases, to only variances. In the present work we propose a methodology to evaluate covariance matrices for thermal and fast neutron induced fission yields. The semi-empirical models adopted to evaluate the JEFF-3.1.1 FY library have been used in the Generalized Least Square Method available in CONRAD (COde for Nuclear Reaction Analysis and Data assimilation) to generate covariance matrices for several fissioning systems such as the thermal fission of U235, Pu239 and Pu241 and the fast fission of U238, Pu239 and Pu240. The impact of such covariances on nuclear applications has been estimated using deterministic and Monte Carlo uncertainty propagation techniques. We studied the effects on decay heat and reactivity loss uncertainty estimation for simplified test case geometries, such as PWR and SFR pin-cells. The impact on existing nuclear reactors, such as the Jules Horowitz Reactor under construction at CEA-Cadarache, has also been considered.
Highlights
To obtain maximum benefit from recent simulation tools and neutron transport codes, significant efforts have been spent to improve the accuracy of input data, whose reliability is a fundamental aspect in estimating precise responses for nuclear technology applications [1]
Uncertainties and biases on nuclear reactor integral parameters have to be known with a certain degree of confidence in order to satisfy the safety-by-design standards required in modern nuclear technology
Many covariance generation strategies have been developed by several organizations to produce complete uncertainty information for Fission product yields (FY) [2,3,4,5]
Summary
To obtain maximum benefit from recent simulation tools and neutron transport codes, significant efforts have been spent to improve the accuracy of input data, whose reliability is a fundamental aspect in estimating precise responses for nuclear technology applications [1]. In the present work we are mainly focused on fission yields. Many covariance generation strategies have been developed by several organizations to produce complete uncertainty information for FY [2,3,4,5]. No covariance values and data formats are available in current nuclear data libraries. In the present work we extensively applied the methodology developed at CEA-Cadarache [6] which aims to faithfully reproduce the existing JEFF3.1.1 library and add consistent covariance information. The results obtained for several fast and thermal neutroninduced fissioning systems have been tested in uncertainty propagation exercises for simple reactor test cases and for the Jules Horowitz Reactor, a high flux material testing facility under construction in the Cadarache site of CEA (France)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
