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Generation of the 1H in H2O neutron thermal scattering law covariance matrix of the CAB model

This work presents an analytic methodology to produce such a covariance matrix-associated to the water model developed at the Atomic Center of Bariloche (Centro Atomico Bariloche, CAB, Argentina). | Generation of the 1H in H2O neutron thermal scattering law covariance matrix of the CAB model EPJ Nuclear Sci. Technol. 4 32 2018 Nuclear Sciences J.P. Scotta et al. published by EDP Sciences 2018 amp Technologies https doi.org 10.1051 epjn 2018024 Available online at https www.epj-n.org REGULAR ARTICLE Generation of the 1H in H2O neutron thermal scattering law covariance matrix of the CAB model Juan Pablo Scotta1 Gilles Noguère1 and Jose Ignacio Marquez Damian2 1 CEA DEN DER Cadarache Saint Paul les Durance France 2 Neutron Physics Departement and Instituto Balseiro Centro Atomico Bariloche CNEA San Carlos de Bariloche Argentina Received 12 October 2017 Received in final form 13 February 2018 Accepted 14 May 2018 Abstract. The thermal scattering law TSL of 1H in H2O describes the interaction of the neutron with the hydrogen bound to light water. No recommended procedure exists for computing covariances of TSLs available in the international evaluated nuclear data libraries. This work presents an analytic methodology to produce such a covariance matrix-associated to the water model developed at the Atomic Center of Bariloche Centro Atomico Bariloche CAB Argentina . This model is called as CAB model it calculates the TSL of hydrogen bound to light water from molecular dynamic simulations. The performance of the obtained covariance matrix has been quantified on integral calculations at cold reactor conditions between 20 and 80 C. For UOX fuel the uncertainty on the calculated reactivity ranges from 71 to 155 pcm. For MOX fuel it ranges from 110 to 203 pcm. 1 Introduction density of states of hydrogen in the water molecule. The objective of the present work is to produce a covariance The calculation of a critical system is carried out by means matrix between the CAB model parameters and to test its of reactor physics simulation code that uses evaluated performance on integral calculations between 20 and 80 C. nuclear data. The evaluated nuclear data libraries contain