Title: Application of positive period method in the calibration and determination of integral worth of MNSR control rod

Authors: A. Asuku; Y.A. Ahmed; I.O.B. Ewa; S.A. Agbo

Addresses: Department of Physics, Ahmadu Bello University, Zaria, Nigeria ' Centre for Energy Research and Training, Ahmadu Bello University, Zaria, Nigeria ' Centre for Energy Research and Training, Ahmadu Bello University, Zaria, Nigeria ' Department of Pure and Applied Physics, Veritas University, Abuja, Nigeria

Abstract: In this work, NIRR-1 control rods were calibrated from 107 mm to 177 mm withdrawal length at a low flux of 5 × 109 n cm−2s−1. Doubling times measurements were carried out in conjunction with the 'Inhour' data to obtain reactor periods and their corresponding reactivities. The integral rod worth of (3.34 ± 0.11) mk obtained here was also compared with the in-built full rod length total reactivity worth of 7 mk and was found to have accounted for 47.8% of it. This result is an indication that 10 mm withdrawal length is approximately 0.488 mk average reactivity insertion and the length used here is the most reactive portion of the control rod. It also shows that only 30% of the control rod length is required to achieve the characteristic curve and also achieve shutdown using the positive period method. This has satisfied the safety requirements of MNSR for shutdown margin.

Keywords: control rods; NIRR-1; Nigeria Research Rector; reactor period; reactivity; MNSR; miniature neutron source reactors; positive period method; calibration; nuclear safety; shutdown margin; nuclear energy; nuclear power.

DOI: 10.1504/IJNEST.2015.075485

International Journal of Nuclear Energy Science and Technology, 2015 Vol.9 No.4, pp.319 - 332

Available online: 24 Mar 2016 *

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