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Description
In this work we calculated two kinetic parameters of the RECH-$1$ research nuclear reactor: the effective delayed neutrons fraction, $\beta_{eff}$, and the mean neutron generation time $\Lambda$ using the Monte Carlo codes MCNP6 [1] and Serpent 2 [2] and the neutron cross section library ENDFV.VII.$1$.
To calculate $\beta_{eff}$ we used the method proposed by Meulekamp and van der Marck[3]. In this method the effective delayed neutron fraction is estimated as
$$ \beta_{eff} \sim 1 - \frac{k_p}{k}, $$ where $k_p$ is the prompt effective neutron multiplication factor and $k$ is the total effective neutron multiplication factor. To calculate the effective neutron generation time we used the pulsed neutron source method[4]. In this technique a burst of neutrons is injected in a subcritical system and then the decay of the neutron population is observed as a function of time. After the system thermalization and decay of higher flux modes, the fundamental-mode decay constant, $\alpha_0$ can be measured using the point kinetic approximation. The relation between $\alpha_0$ and the reactivity, $\rho$, is obtained from the point kinetics equations: $$ \alpha_0 = \frac{\rho - \beta_{eff}}{\Lambda}. $$
These calculations will be contrasted with reactor operation experimental campaign results during next year.
- T. Goorley, et al., Initial MCNP6 Release Overview, Nuclear Technology, 180 (2012), 298-315.
- Leppanen, J., et al., The Serpent Monte Carlo code: Status, development and applications in 2013. Ann. Nucl. Energy, 82 (2015) 142-150.
- Meulekamp, R.K., van der Marck, S.C., Calculating the effective delayed neutron fraction with Monte Carlo. Nucl. Sci. Eng. 152 (2006), 142–148.
- Simmons, B.E., King, J.S., A pulsed neutron technique for reactivity determination. Nuclear Science and Engineering 3 (1958), 595–608.
