Analysis of reactivity determination methods in the subcritical experiment Yalina

Monte Carlo modeling and analyses of YALINA-booster subcritical assembly part 1: analytical models and main neutronics parameters.

“…The calculated effective neutron multiplication factor (k eff ) of 0.97972 differs only 220 pcm from the recent experimental measurements, which represents a factor 10 improvement relative to similar published results. 6 The MCNP multiplication factor results with 204 Pb isotope represented as 206 Pb or 207 Pb are within the statistical error. The k eff results from the MCNP code version 5 and 4c3 agree with the result from the MCNPX code within the statistical error.…”

“…5 The analyses include the calculation of the multiplication factor and the main neutronics parameters, such as the effective delayed neutron fraction (β eff ), the prompt neutron lifetime (l p ), and generation time (Λ). The YALINA-Booster subcritical research facility [5][6] of Belarus has been investigated by two Monte Carlo codes. MONK9a, [7][8] which is used for licensing nuclear power plants in the United Kingdom and MCNP/MCNPX/MCB, [9][10][11][12][13][14][15][16] which is used all over the world for analyzing nuclear facilities and benchmarking other transport codes.…”

Validation of ADS reactivity monitoring techniques in the Yalina-Booster subcritical assembly

“…Pulsed neutron experiments have shown that it is possible to determine the reactivity of the system using the kinetic response of the neutron flux after a short source injection (Soule et al, 2004;Villamarín, 2004;Jammes et al, 2006;Persson et al, 2005;Talamo et al, 2009;Berglof et al, 2010;Mellier et al, 2005). Conceptually, this situation is equivalent to a continuous source produced with an accelerator, where the beam is interrupted very quickly and restarted again after a few milliseconds.…”

“…Most of the techniques applied up to now to determine the reactivity of a subcritical system that cannot become critical are based on Pulsed Neutron Source (PNS) experiments. PNS experiments have been carried out in the MUSE (Soule et al, 2004;Villamarín, 2004), TRADE (Jammes et al, 2006), RACE (Jammes, 2007), Yalina-Thermal (Persson et al, 2005) or Yalina-Booster (Talamo et al, 2009(Talamo et al, , 2012Berglof et al, 2010) subcritical assemblies to validate PNS techniques and therefore they are today well documented and can be taken as reference. However, during the normal operation of an industrial ADS, the power must be stable and continuous, and these techniques cannot be applied.…”

A useful observable for estimating keff in fast subcritical systems

“…Accelerator Driven Systems, ADS) and a paramount indicator to monitor its subcriticality level. However, it is not directly an observable: its determination is essentially an inverse problem and various ad-hoc methods [1][2][3][4][5][6][7] have been developed for its experimental determination from flux measurements; they have been tested against experimental results from MUSE [8], YALINA [9], DELPHI [10] and VENUS-F [11] with different findings, mainly depending on the subcriticality level. Additionally, it is important to highlight that their applicability is debatable when the value of k e f f is below 1.…”