Safety features of self-consistent nuclear energy system

Journal of Nuclear Science and Technology

Ninokata

2009

Self-controllability and self-terminability are strongly required as passive safety features in future liquid-metal FBR (LMFBR) commercialization. In this study, the self-terminability of the MN-fueled core was focused on. The FBR cores including the MN-fueled core should be designed to eliminate severe recriticality leading to energetics during core disruptive accidents (CDAs) because the cores are not designed to operate in an optimum configuration from a reactivity point of view. In addition, in the case of the MN-fueled core, the nitrogen gas N 2 generated by the thermal dissociation, one of the unique phenomena of the nitride fuel, would give another cause of reactor vessel failure. Such a mechanical effect would strongly depend on the magnitude of the void reactivity. In this study, the allowable maximum void reactivity of the MN-fueled core to maintain the mechanical integrity of the reactor vessel was evaluated against an Unprotected Loss-of-Flow (ULOF) accident by using ARGO taking into account the equation-of-state of the MN fuel. By considering the partial-pressure-dependent thermal dissociation process, the design limit of the core void reactivity (positive sum) was estimated to be 6.2 $.

Section: Results Of the Ulof Calculationmentioning

confidence: 99%

Section: Inherent Safety Features Of Fbr Coresmentioning

confidence: 99%

On Void Reactivity Limitation for the Core Loaded with Mixed Nitride Fuels

Journal of Nuclear Science and Technology

Ninokata

2009

“…In order to intensify the licensability and public acceptance for the near-future FBR, the authors are emphasizing the FBR safety concepts of ''self-controlla-bility'' and ''self-terminability'' to obtain the inherent safety features against the scram failure event such as the unprotected loss of flow (ULOF), which is a typical CDA initiator of the FBR. 1,2) The self-controllability is defined as the capability to eliminate the fuel failure propagating to the CDA by using the negative reactivity feedback induced by the temperature increase of core materials during the unscrammed events. 3) The self-terminability is a capability to exclude superprompt criticality conditions leading to the energetics during CDA.…”

Section: Requirement Of Self-controllabilitymentioning

confidence: 99%

Study of the Self-Controllability for the Fast Reactor Core with High-Thermal-Conductivity Fuel

Yokoyama

et al. 2010

J. Nucl. Sci. Technol.

The tolerance capability against ATWS for the FBR core with metallic fuel can be improved by employing a fuel with high thermal conductivity (HTC fuel) instead of the conventional metallic fuel, U-Pu-Zr. To investigate the self-controllability for the HTC-fueled core with U-Pu-Al alloy fuel, having one order of magnitude higher thermal conductivity than that of the U-Pu-Zr, the core employing the U-Pu-Al fuel was evaluated against ULOF and UTOP. Based on the systematic calculation, it was found that the larger temperature margin between the steady state and ULOF/UTOP conditions caused the excellent tolerance capability against ULOF and UTOP for the HTC-fueled core compared with that for the Zralloy-fueled core. Also, the conditions of the core reactivity coefficients required for neither fuel melting nor coolant boiling were investigated by using a ''self-controllability map'' consisting of effective fuel and coolant reactivities. As a result, the self-controllable region was found to be expanded especially for UTOP in the case of the HTC-fueled core.

“…The objectives of this study are (1) to investigate the material candidate of the HTC fuel, (2) to evaluate the capability of the self-controllability for the typical HTCfueled core compared with the Zr-alloy-fueled core, (3) to obtain the self-controllability safety map, and (4) to examine the design of the HTC-fueled core satisfying the self-controllability.…”

Section: Objective Of This Studymentioning

confidence: 99%

“…In order to intensify the licensability and public acceptance for the near-future FBR, the authors are emphasizing the FBR safety concepts of ''self-controllability'' and ''self-terminability'' to obtain the inherent safety features against the scram failure event such as the unprotected loss of flow (ULOF), which is a typical CDA initiator of the FBR. 1,2) The self-controllability is defined as the capability to eliminate the fuel failure propagating to the CDA by using the negative reactivity feedback induced by the temperature increase of core materials during the unscrammed events.…”

Section: Requirement Of Self-controllabilitymentioning

confidence: 99%

Study of the Self-Controllability for the Fast Reactor Core with High-Thermal-Conductivity Fuel

Yokoyama

Journal of Nuclear Science and Technology

et al. 2010

The tolerance capability against ATWS for the FBR core with metallic fuel can be improved by employing a fuel with high thermal conductivity (HTC fuel) instead of the conventional metallic fuel, UPu-Zr. To investigate the self-controllability for the HTC-fueled core with U-Pu-Al alloy fuel, having one order of magnitude higher thermal conductivity than that of the U-Pu-Zr, the core employing the U-Pu-Al fuel was evaluated against ULOF and UTOP. Based on the systematic calculation, it was found that the larger temperature margin between the steady state and ULOF/UTOP conditions caused the excellent tolerance capability against ULOF and UTOP for the HTC-fueled core compared with that for the Zralloy-fueled core. Also, the conditions of the core reactivity coefficients required for neither fuel melting nor coolant boiling were investigated by using a ''self-controllability map'' consisting of effective fuel and coolant reactivities. As a result, the self-controllable region was found to be expanded especially for UTOP in the case of the HTC-fueled core.