EPJ Nuclear Sci. Technol. 4, 42 (2018)
https://doi.org/10.1051/epjn/2018023

Regular Article

Sensitivity and uncertainty analysis of β_eff for MYRRHA using a Monte Carlo technique

¹ Institute for Advanced Nuclear Systems, Belgian Nuclear Research Centre (SCK∙CEN), Boeretang 200, 2400 Mol, Belgium
² J-PARC Center, Japan Atomic Energy Agency (JAEA), 2-4, Shirakata, Tokai-mura, Naka-gun, Ibaraki 319-1195, Japan
³ Data Bank, OECD Nuclear Energy Agency (NEA), 46, Quai Alphonse Le Gallo 92100 Boulogne-Billancourt, France

^* e-mail: iwamoto.hiroki@jaea.go.jp

Received: 3 October 2017
Received in final form: 26 January 2018
Accepted: 14 May 2018
Published online: 14 November 2018

Abstract

This paper presents a nuclear data sensitivity and uncertainty analysis of the effective delayed neutron fraction β_eff for critical and subcritical cores of the MYRRHA reactor using the continuous-energy Monte Carlo N-Particle transport code MCNP. The β_eff sensitivities are calculated by the modified k-ratio method proposed by Chiba. Comparing the β_eff sensitivities obtained with different scaling factors a introduced by Chiba shows that a value of a = 20 is the most suitable for the uncertainty quantification of β_eff. Using the calculated β_eff sensitivities and the JENDL-4.0u covariance data, the β_eff uncertainties for the critical and subcritical cores are determined to be 2.2 ± 0.2% and 2.0 ± 0.2%, respectively, which are dominated by delayed neutron yield of ²³⁹Pu and ²³⁸U.