Prompt Neutron Decay Constant in Esfahan Light Water Subcritical Reactor (ELWSCR): Comparison of Rossi-α Experiment and Monte Carlo Simulation

Arkani, M; Khalafi, H; Khakshournia, S; Vosoughi, N

Prompt Neutron Decay Constant in Esfahan Light Water Subcritical Reactor (ELWSCR): Comparison of Rossi-α Experiment and Monte Carlo Simulation

Document Type : Research Paper

Authors

M Arkani

H Khalafi

S Khakshournia

N Vosoughi

Abstract

Rossi-α method is one of the useful techniques for diagnosis of subcritical nuclear reactors. In the present work, Rossi- α method was used to measure the prompt neutron decay constant of the reactor core of the Esfahan Light Water Subcritical Reactor (ELWSCR), and to drive the neutron chain reactions, a ²⁵²Cf neutron source was used. The experimental data in the form of the arrival time of the stochastic pulses were collected by a dedicated data acquisition system, and the required data were stored in a PC. Offline processing of the data was performed by the MATLAB software engineering tool, and Rossi distribution was extracted. Finally, by the curve fitting of Rossi distribution function to the processed data, the prompt neutron decay constant of the core was determined. Based on MCNPX code simulation, the reactor core was also studied. A comparison of the results obtained by the two methods shows a fairly good agreement.

Keywords

Subcritical Reactor

Rossi-α Analysis

Prompt Neutron Decay Constant

MCNPX Code

20.1001.1.17351871.1396.38.2.3.3

[1] H.G. Hughes, et al., MCNPXTM 2.4.0, User´s Manual, Version 2.4.0, Los Alamos National Laboratory, LA-CP-02-408 (2002).

[2] M. Arkani, H. Khalafi, N. Vosoughi, Development of an embedded FPGA-based data acquisition system dedicated to zero power reactor noise experiments, Metrol. Meas. Syst. 21 (2014) 433–446.

[3] M. Arkani, Measurement of Tehran and Esfahan Research Reactors Kinetic Parameters using Reactor Noise Diagnostic Methods, Nuclear Science and Technology Research Institute, Ph.D. Thesis (2015).

[4] Mathworks, MATLAB Reference Guide. The Math Works Inc, (2013).

[5] M. Arkani, H. Khalafi, N. Vosoughi, S. Khakshournia, A FPGA based Time Analyser for Stochastic Methods in Experimental Physics, Instrum. Exp. Technol. 3 (2015) 350-358.

[6] M. Arkani, H. Khalafi, N. Vosoughi, S. Khakshournia, Design and construction of a two-channel data acquisition system for random processes based on FPGA, J. Nucl. Sci. Tech. 76 (2016) 29-38.

[7] J.A. Thie, Reactor Noise, Rowman and Littlefield Inc., New York (1963).

[8] R.E. Uhrig, Random Noise Techniques in Nuclear Reactor Systems, the Ronald Press Company, New York (1970).

[9] M.M.R. Williams, Random Process in Nuclear Reactors, Pergamom Press (1974).

[10] F. Akino, H. Yasuda, Y. Kaneko, Determination of large negative reactivity by integral versions of various experimental methods, Nucl. Sci. Technol. 17 (1980) 593-615.

[11] P. Baeten, Heuristic derivation of the Rossi-α formula for a pulsed neutron source, Ann. Nucl. Energ. 31 (2004) 43-53.

[12] Y. Kitamura, M. Matoba, T. Misavita, H. Unesaki, S. Shiroya, Reactor Noise Experiments by using Acquisition System for Time Series Data of Pulse Train, Nucl. Sci. Technol. 36 (1999) 653-660.

[13] Y. Kitamura, I. Pázsit, J. Wright, A. Yamamoto, Y. Yamane, Ann. Nucl. Energ. 32 (2005) 671-692.

[14] Y. Kitamura, K. Taguchi, T. Misawa, I. Pázsit, A. Yamamoto, Y. Yamane, C. Ichihara, H. Nakamura, H. Oigawa, Calculation of the stochastic pulsed Rossi-α formula and its experimental verification, Prog. Nucl. Energ. 48 (2006) 37-50.

[15] G.E. Ragan, J.T. Mihalczo, R.C. Robinson, Prompt neutron decay constants at delayed criticality for the Oak Ridge Research Reactor with 20 and 93 wt% 235U enriched fuel, Ann. Nucl. Energ. 24 (1997) 21-31.