Physics study of Canada deuterium uranium lattice with coolant void reactivity analysis

This study presents a coolant void reactivity analysis of Canada Deuterium Uranium (CANDU)- 6 and Advanced Canada Deuterium Uranium Reactor-700 (ACR-700) fuel lattices using a Monte Carlo code. The reactivity changes when the coolant was voided were assessed in terms of the contributions of four factors and spectrum shifts. In the case of single bundle coolant voiding, the contribution of each of the four factors in the ACR-700 lattice is large in magnitude with opposite signs, and their summation becomes a negative reactivity effect in contrast to that of the CANDU-6 lattice.
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Physics study of Canada deuterium uranium lattice with coolant void reactivity analysis N u c l e a r E n g i n e e r i n g a n d T e c h n o l o g y 4 9 ( 2 0 1 7 ) 6 e1 6 Available online at ScienceDirect Nuclear Engineering and Technology journal homepage: www.elsevier.com/locate/net Original Article Physics Study of Canada Deuterium Uranium Lattice with Coolant Void Reactivity Analysis Jinsu Park a, Hyunsuk Lee a, Taewoo Tak a, Ho Cheol Shin b, and Deokjung Lee a,* a Ulsan National Institute of Science and Technology, 50, UNIST-gil, Ulsan, 44919, Republic of Korea b Korea Hydro and Nuclear Power Central Research Institute (KHNP-CRI), 70, Yuseong-daero 1312beon-gil, Yuseong-gu, Daejeon, 34101, Republic of Korea article info abstract Article history: This study presents a coolant void reactivity analysis of Canada Deuterium Uranium (CANDU)- Received 18 February 2016 6 and Advanced Canada Deuterium Uranium Reactor-700 (ACR-700) fuel lattices using a Monte Received in revised form Carlo code. The reactivity changes when the coolant was voided were assessed in terms of the 24 May 2016 contributions of four factors and spectrum shifts. In the case of single bundle coolant voiding, Accepted 1 July 2016 the contribution of each of the four factors in the ACR-700 lattice is large in magnitude with Available online 29 July 2016 opposite signs, and their summation becomes a negative reactivity effect in contrast to that of the CANDU-6 lattice. Unlike the coolant voiding in a single fuel bundle, the 2  2 checkerboard Keywords: coolant voiding in the ACR-700 lattice shows a positive reactivity effect. The neutron current Advanced Canada Deuterium between the no-void and voided bundles, and the four factors of each bundle were analyzed to Uranium Reactor-700 figure out the mechanism of the positive coolant void reactivity of the checkerboard voiding Canada Deuterium Uranium-6 case. Through a sensitivity study of fuel enrichment, type of burnable absorber, and moderator Coolant Void Reactivity to fuel volume ratio, a design strategy for the CANDU reactor was suggested in order to achieve Sensitivity Study a negative coolant void reactivity even for the checkerboard voiding case. Single Bundle and Checkerboard Copyright © 2016, Published by Elsevier Korea LLC on behalf of Korean Nuclear Society. This Voiding is an open access article under the CC BY-NC-ND license (http://creativecommons.org/ licenses/by-nc-nd/4.0/). 1. Introduction fuel bundle, which is an advanced fuel bundle design developed by AECL along with Korean Atomic Energy Research Institute for The Canada Deuterium Uranium (CANDU) reactor has been use in CANDU design nuclear reactors [3]. The CANFLEX fuel widely used in many countries because of its advantages such as bundle contains slightly enriched uranium in the outer rods and its low absorption cross section of heavy water and inexpensive natural uranium with burnable poison in the central rod. The fuel manufacturing cost [1]. The Advanced CANDU Reactor-700 most significant improvement is that the lattice of ACR-700 has (ACR-700) was proposed by Atomic Energy of Canada Limited a negative coolant void reactivity (CVR), unlike the previous (AECL) as a next-generation CANDU reactor [2]. The main CANDU lattice. changes of ACR-700 are reducing the fuel pitch, changing the Models of the CANDU-6 and ACR-700 fuel lattices were con- coolant material from heavy water to light water, and changing structed for a single bundle to understand the physics related to the 37-element CANDU-6 fuel bundle to a 43-element CANFLEX CVR. However, the fuel channels were connected in a CANDU * Corresponding author. E-mail address: deokjung@unist.ac.kr (D. Lee). http://dx.doi.org/10.1016/j.net.2016.07.003 1738-5733/Copyright © 2016, Published by Elsevier Korea LLC on behalf of Korean Nuclear Society. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).  N u c l e a r E n g i n e e r i n g a n d T e c h n o l o g y 4 9 ( 2 0 1 7 ) 6 e1 6 7 core with two independent pressure heads in a checkerboard Models of a single fuel bundle were constructed by MCNP6 pattern. In addition, the coolants of adjacent channels flowed in using the ENDF/B-VII.0 continuous energy cross section li- opposite directions. Therefore, in the case of a pressure pump brary based on the specification from Atomic Energy of Can- failure in a loss-of-coolant accident, the coolant within a CANDU ada Limited. The Monte Carlo simulation parameters were set core does not void uniformly in 1e2 seconds, owing to the to 500,000 histories per cycle with 400 active cycles and 100 remaining pressure head. In other words, there may be coolant inactive cycles, in order to keep the standard deviatio ...