Design Study of Innovative Simplified Small Pebble Bed Reactor

Transcription

1 Design Study of Innovative Simplified Small Pebble Bed Reactor Dwi Irwanto 1* and Toru OBARA 2 1 Department of Nuclear Engineering, Tokyo Institute of Technology 2 Research Laboratory for Nuclear Reactors, Tokyo Institute of Technology Ookayama, Meguro-ku, Tokyo , Japan

2 Contents o Introduction o Calculation Procedures o Parametric Surveys for Introducing Thorium in the Fuel Composition o Calculation results using Thorium Fuel and its comparison with Uranium Fuel design o Conclusions

3 INTRODUCTION

4 Introduction Pebble Bed Reactor (Potential) Problem? The unloading machinery is a very complex and high cost system

5 Introduction Peu a Peu Fuel Loading Scheme Based on pebble bed reactor Startup lower layers filled first criticality During operation layer per layer filled maintain criticality The end of the core unloaded fuel

6 Purpose Neutronic and steady state thermal hydraulic analysis using Uranium fuel have been performed in the previous studies [1], [2], [3] for a small simplified Pebble Bed Reactor. The purpose of the present study is to analyze the effect of introducing thorium in the fuel compound of peu à peu concept by firstly performing a parametric surveys to find the best fuel configuration in order to achieved better burnup characteristics of the reactor system. 1) D.Irwanto and T. Obara, Design Study of Innovative Simplified Small Pebble Bed Reactor (1) Design Concept and Sample Design Analysis, AESJ Fall Meeting, ) D.Irwanto and T. Obara, Design Study of Innovative Simplified Small Pebble Bed Reactor (2)Thermal Hydraulic Analysis of the Reference Design, AESJ Fall Meeting, ) D.Irwanto and T. Obara, Design Study of Innovative Simplified Small Pebble Bed Reactor (3)Analysis of the 110 MWt Simplified PBR Design with Peu a Peu Fuel Loading Concept, AESJAnnual Meeting, 2011

7 CALCULATION PROCEDURES

8 Calculation Procedures Diffusion method vs Monte Carlo method Empty Region Calculation procedures for the Peu à Peu modus require lot of steps A computer code to automate the process of the Peu à Peu fuel load scheme need to be developed [1] Pebble Balls 1) D.Irwanto and T. Obara, Design Study of Innovative Simplified Small Pebble Bed Reactor (1) Design Concept and Sample Design Analysis, AESJ Fall Meeting, 2009

9 PARAMETRIC SURVEYS FOR INTRODUCING THORIUM IN THE FUEL COMPOSITION

10 Parametric Surveys In the infinite geometry to find the best fuel configuration Parametric survey for introducing thorium in the fuel composition

11 CALCULATION RESULTS USING THORIUM FUEL AND ITS COMPARISON WITH URANIUM FUEL DESIGN

12 Calculation Conditions Design Specification Reactor Power 110 MWth Fuel TRISO Core radius 200 cm Core Height 1026 cm Reflector width 70 cm Startup fuel layers 186 cm Initial 235 U enrichment 15.0 % Supply fuel 235 U enrichment 15.0 % Packing Fraction 7.0 % Schematic view of reactor core design Thorium fraction 30.0 % page 22 of 29

13 Calculation Conditions Fuel Ball Diameter of the ball 6.0 cm Diameter of fuel zone 5.0 cm Packing fraction of Coated Fuel Particle (CFP) 7.0 % Enrichment of 235 U 5 % Equivalent natural boron content of impurities in uranium Packing fraction of fuel and dummy balls in the core 4.0 ppm 61 % Coated Fuel Particle Fuel Kernel Material UO 2 Radius of the kernel mm Density 10.4 g/cm 3 Coatings First Buffer Layer (PyC) Thickness 0.09 mm Density 1.1 g/cm 3 Second Layer (PyC) Thickness 0.04 mm Density 1.9 g/cm 3 Third Layer (SiC) Thickness mm Density 3.18 g/cm 3 Forth Layer (PyC) Thickness 0.04 mm Density 1.9 g/cm 3

14 Calculation Results Effective multiplication factor during reactor operation

15 Calculation Results Relative Power Distribution at the end of reactor life

16 Calculation Results Fissile isotope densities at the end of reactor operation

17 COMPARISON BETWEEN THORIUM-URANIUM FUEL AND URANIUM FUEL

18 Calculation Results Burnup at the beginning of reactor operation (BOL)

19 Calculation Results Burnup at the middle of reactor operation (MOL)

20 Calculation Results Burnup at the end of reactor operation (EOL)

21 Fuel Economics Reactor Design Reference Design 1 Reference Design 2 U+Th Design Fuel Uranium Enrichment Thorium Fraction Average Burnup (GWD/T) Natural Uranium needed per MWe per year (Tons) Natural Uranium uses compare with reference design1 Natural Uranium uses compare with reference design2 Uranium 5% Uranium 12% Thorium + Uranium 15% 30% % smaller 13.4% smaller

22 CONCLUSIONS

23 Conclusions o Feasibility to simplified pebble bed reactor by removing the unloading device from the system have been confirmed for both uranium and thorium fuel using Peu a Peu fuel loading concept. o Parametric surveys result: the best fuel configuration could be obtained for 30% of thorium and 70% of uranium fraction with 15% uranium enrichment and 7% of packing fraction of CFP inside the pebble ball. page 25 of 29

24 Conclusions o Optimization of the thorium fuel configuration for the Peu a Peu concept have been performed and implemented on a 110 MWt. As a result, this reactor could be operated for 21.4 years with the average and maximum burnup value is GWD/T and GWD/T, respectively; which is significantly higher than the reference cases using only uranium as fuel. o Requirement of total natural uranium during reactor operation could be reduced as 33.3% and 13.4% for reactor with the optimized thorium-uranium fuel configuration compared with those of the reference design 1 and 2, respectively, which were using only uranium fuel. page 25 of 29

25 THANK YOU