Neutronic Study of Fast Reactor with Modified CANDLE Burnup Scheme Using natural Pb, Pb(nat)-Bi Eutectic,²⁰⁸Pb, and²⁰⁸Pb-Bi Eutectic as Coolant

Abstract

About 96% of reactors in the world consume enriched uranium. However, enrichment technology is costly and a sensitive issue related to nuclear non-proliferation. Whereas, without the technology, it is difficult to obtain the optimal benefits from the nuclear reactor. The long-life reactor designs that can consume natural uranium and minimize initial fue l loading are needed. Therefore, the design study of long-life Pb(208)-Bi eutectic cooled reactor with modified CANDLE (Constant Axial shape of Neutron flux, nuclide densities, and power shape During Life of Energy Energy production) burn up scheme has performed. Modified CANDLE burnup scheme can use natural Uranium (without enrichment) as fuel and also can reprocess LWR (Light-Water Reactor) spent fuel. In Modified CANDLE scheme, a reactor core is divided into 10 regions in an axial direction which has the same volume. Region 1 is filled by fresh natural uranium and after 10 years burnup, it is then shifted to region 2. These mechanisms are applied to all the regions. Coolant for LFR (Lead-cooled Fast Reactors) have some requirements such as has low neutron absorption, low melting point, high boiling point and non-reactive with air and water. Pb(208)-Bi eutectic is a promising coolant for LFR due to its properties. The Neutronic calculation was performed by SRAC and FITB.ch1 using JENDL 4.0 as nuclear data library. The Important neutronic parameter such as k-eff is discussed in the present study. Initial k-eff of the reactor using Pb-natural, Pb-Bi, Pb(208), and Pb(208)-Bi as coolant are 0.99973, 1.0020, 1.0089, and 1.0059, respectively.

Design study of a 450MW thermal Modified CANDLE fast reactor using helium gas as a coolant

“…Several innovative reactor concepts have been proposed to reduce the problems regarding the safety and high cost of current power reactors [3], [6]. Among them, Sekimoto et al elaborated the CANDLE (Constant Axial shape of Neutron flux, nuclide densities and power shape During the Life of Energy production) reactor and Zaki Su'ud elaborated on the Modified CANDLE (MCANDLE) reactor [7]. Those types of reactors can utilize natural uranium for fresh fuel without needing enrichment or reprocessing [8], [9], [10].…”