Study on Transmutation of Minor Actinides as Burnable Poison in VVER-1000 Fuel Assembly

Vinh Thanh Tran,Pham Nhu Viet Ha,Van-Khanh Hoang,Hoai-Nam Tran,Huu Tiep Nguyen

doi:10.1155/2019/5769147

Abstract

Thermal reactors have been considered as interim solution for transmutation of minor actinides recycled from spent nuclear fuel. Various studies have been performed in recent decades to realize this possibility. This paper presents the neutronic feasibility study on transmutation of minor actinides as burnable poison in the VVER-1000 LEU (low enriched uranium) fuel assembly. The VVER-1000 LEU fuel assembly was modeled using the SRAC code system, and the SRAC calculation model was verified against the MCNP6 calculations and the available published benchmark data. Two models of minor actinide loading in the LEU fuel assembly have been investigated: homogeneous mixing in the UGD (Uranium-Gadolinium) pins and coating a thin layer to the UGD pins. The consequent negative reactivity insertion by minor actinides was compensated by reducing the gadolinium content and boron concentration. The reactivity of the LEU assembly versus burnup and the transmutation of minor actinide nuclides were examined in comparison with the reference case. The results demonstrate that transmutation of minor actinides as burnable poison in the VVER-1000 reactor is feasible as minor actinides could partially replace the functions of gadolinium and boric acid for excess reactivity control.

Highlights

It is recognized that the negative fames of nuclear energy, i.e., the current nuclear power plants (NPPs) being operated worldwide for electricity generation, are the release of radioactive materials under normal, abnormal, or accident conditions and the by-products of highly radioactive, longlived spent nuclear fuels
In the SRAC simulation, the one-sixth of the low enriched uranium (LEU) fuel assembly is modeled with the PIJ module, the fuel burnup calculations are performed with the BURN-UP module, and the 107 energy groups based on the ENDF/B-VII.0 nuclear data library are used. e LEU fuel assembly modeled with SRAC is verified against the Monte Carlo code MCNP6 calculations and the published benchmark data for the S1 state, i.e., the normal operating poisoned state with 135Xe and 149Sm equilibrium concentrations. e parameters to be compared include the infinite multiplication factor (k-inf ) of the fuel assembly versus burnup and nuclide concentrations
Conclusions e possibility of minor actinides (MAs) transmutation as burnable poison in the VVER-1000 LEU fuel assembly was examined using the SRAC code system. e SRAC calculation model for the VVER-1000 LEU fuel assembly was verified against the MCNP6 calculations and the available published benchmark results

Summary

Research Article

Study on Transmutation of Minor Actinides as Burnable Poison in VVER-1000 Fuel Assembly. Is paper presents the neutronic feasibility study on transmutation of minor actinides as burnable poison in the VVER-1000 LEU (low enriched uranium) fuel assembly. Two models of minor actinide loading in the LEU fuel assembly have been investigated: homogeneous mixing in the UGD (Uranium-Gadolinium) pins and coating a thin layer to the UGD pins. E consequent negative reactivity insertion by minor actinides was compensated by reducing the gadolinium content and boron concentration. E reactivity of the LEU assembly versus burnup and the transmutation of minor actinide nuclides were examined in comparison with the reference case. E results demonstrate that transmutation of minor actinides as burnable poison in the VVER-1000 reactor is feasible as minor actinides could partially replace the functions of gadolinium and boric acid for excess reactivity control Two models of minor actinide loading in the LEU fuel assembly have been investigated: homogeneous mixing in the UGD (Uranium-Gadolinium) pins and coating a thin layer to the UGD pins. e consequent negative reactivity insertion by minor actinides was compensated by reducing the gadolinium content and boron concentration. e reactivity of the LEU assembly versus burnup and the transmutation of minor actinide nuclides were examined in comparison with the reference case. e results demonstrate that transmutation of minor actinides as burnable poison in the VVER-1000 reactor is feasible as minor actinides could partially replace the functions of gadolinium and boric acid for excess reactivity control

Introduction

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Findings

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