Royal Military College of Canada

Energy and Nuclear Science

Monte Carlo Simulation of the Leu-Fueled Slowpoke-2 Nuclear Reactor Using MCNP 4A

By: Dr. Hugues W. Bonin & Lt(N) Martin Pierre

The availability of the Monte Carlo-based code MCNP 4A has made possible the simulation of the low-enriched uranium (LEU)-fueled SLOWPOKE-2 reactor using a probabilistic approach. The reactor core and its surrounding pool can be modeled in three dimensions with numerous details included in the representation. Significant improvement from previous modeling attempts was obtained with the MCNP 4A simulation, with the discrepancy between the calculated and experimental values of the excess reactivity at 20ºC reduced to only 0.2 mk. The analysis suggests the error on the MCNP 4A-calculated excess reactivity as between 1 and 2 mk.

The SLOWPOKE-2 reactor was then simulated with its single control rod at various degrees of insertion in the core. The reactivity worth of the control rod was calculated as 7.85 mk, only 2.4 mk above the measured value. MCNP 4A was then used for predicting the temperature effects on the excess reactivity. Although the inherent safety of the SLOWPOKE-2 reactor was confirmed in the simulation, the temperature dependence of the excess reactivity could not however be accurately predicted, due for the most part to the lack of appropriate cross-section libraries available at the time of this work. The potential of MCNP 4A is nevertheless clearly demonstrated for the simulation of the LEU-fueled SLOWPOKE-2 reactor, once the missing cross sections become available for the low temperatures at which the reactor operates.

SCHEMATICS OF THE SLOWPOKE-2 REACTOR CORE

Schematics of the SLOWPOKE-2 reactor core

SLOWPOKE-2 REACTOR

SLOWPOKE-2 Reactor representation used in code MCNP 4A

SAMPLE PUBLICATIONS:

  • J.R.M. Pierre & H.W. Bonin, "LEU-Fueled SLOWPOKE-2 Modeling with MCNP 4A", Proceedings of the 17th Annual Conference of the Canadian Nuclear Society, Fredericton, New Brunswick, 9-12 June 1996, Vol. !, Session B.1.
  • J.R.M. Pierre & H.W. Bonin, "Monte-Carlo Simulation of the LEU-Fueled SLOWPOKE-2 Nuclear Reactor Using MCNP 4A", Nuclear Technology, Vol. 125, No. 1, Jan 1999, pp. 1-12.
  • J.R.M. Pierre, "Mathematical Modelling of the SLOWPOKE-2 Nuclear Reactor at RMC Using Monte-Carlo Methods", Master's degree thesis, Royal Military College of Canada, Kingston, Ontario, April 1996.