Core Modification for the High Burn-up to Improve Irradiation Efficiency of the Experimental Fast Reactor Joyo

Transcription

1 Core Modification for the High Burn-up to Improve Irradiation Efficiency of the Experimental Fast Reactor Joyo S. Maeda, M. Yamamoto, T. Soga, T. Furukawa and T. Aoyama Oarai R&D Center Japan Atomic Energy Agency International Conference on Fast Reactors and Related Fuel Cycles s (FR09) 1

2 History of Joyo Mission (1) To Accumulate Technical Experience of FR through planning, construction and operation (2) Irradiation facility for FR Fuels and Materials Design Groundbreaking The first criticality achieved at Joyo The 1st criticality Mark-Ⅰ Mark-Ⅱ Modification works The 1st criticality Mark-Ⅲ

3 Introduction of Joyo Shielding Subassembly (B 4 C : B Enrichment : 45wt%) Reflector ( Stainless Steel ) Outer Fuel Subassembly Inner Fuel Subassembly Irradiation Test Subassembly Control Rod (B 4 C: B Enrichment : 90wt%) 80 cm MK-II Core MK-III Core Max. No. of Driver Fuel S/A Max. No. of Test Fuel S/A 9 21 Core Diameter (cm) Core Height (cm) U Enrichment (wt%) 12(J1)/18(J2) ~18 Pu Content Total (wt%) <30 <30 Fissile (Inner/Outer) ~20 ~16/21 Max. Linear Heat Rate (W/cm) Reactor Thermal Power (MWt) Neutron Flux(>0.1MeV)(n/cm 2 s) MK- ⅢCore MK-ⅡCore Row 6 3

4 Maximum burn-up(gwd/t) Problem The number of Irradiation test rig with little nuclear fuel Increases in MK-III. Need to remove driver fuel at low burn-up in order to compensate excess reactivity decrease. MK-II(J1) MK-II(J2) MK-II Fuel MK-III Inner Fuel MK-III Outer Fuel Burn-up Limit MK-III MK-II Core MK-III Core Cycle number MK-II Reach to designated Burn-up MK-III About 70% of licensed Burn-up Low Burn-up of Driver Fuel in MK-III Core 4

5 How to Increase the Core Burn-up Core Modification to compensate the core reactivity decrease 1. Installation of zirconium reflectors around the driver fuel region to improve the neutron efficiency 2. Replacing one control rod with fuel to increase the fuel inventory Inner Driver Fuel Outer Driver Fuel Irradiation Rig Control Rod Outer Reflector Shielding Assembly Inner Reflector (SUS) Inner Reflector (Zr) 5

6 Installation of zirconium reflectors Outer Reflector Inner Reflector Fuel Region Joyo MK-III core Reflector Element Wrapper Tube Spacer Pad Specification of inner reflector Subassembly length Reflector element length Reflector material 2970mm 650mm Modified 316SS, PNC1540, Zirconium alloy Number of elements 7 Volume ratio of the reflector material 70% σσ absorption :Ni(0.030)> Zr(0.016) Fe(0.0) > Fe(0.011) Zr(0.008) unit:barn Σσ scattaring :Ni(6.6) > Zr(6.0) Fe(3.5) > Fe(3.7) Zr(2.8) unit:barn Zirconium s Mass num.:zr(91.2)> nuclear characteristics Ni(58.7) provide a Fe(55.8) reflection of neutrons with less absorption N. D. :Ni(1.0) than austenitic Fe(0.94) stainless steel > or Zr(0.47) high nickel a. u. alloys 6

7 Calculation Code JUPITER standard fast reactor analysis method Code : Xsec set: Energy Gr. : CITATION-FBR (Diffusion theory, 3D Tri-Z geometry) TRITAC (Transport theory, 3D XYZ geometry) PERKY (Perturbation theory) JFS-3-J3.2R based on JENDL Gr. or 7Gr. Applying a C/E correction method Effect of Zr reflector Excess Reactivity Change (SS -> Zr) Refueling (12Fuel) % k/kk Excess Reactivity Present Burn-up -1.6 % k/kk /cycle Operation days Making use of a driver fuel longer 7

8 Changing of refueling batch number To maximize the fuel burn-up within the licensed burn-up limitation (90 GWd/t) Item SS Reflector Zr Reflector Number of Refueling(S/As) 12 Maximum Fast Neutron Flux (E>0.1 MeV)( 15 n/cm 2 s) Maximum burn-up [GWd/t] Maximum burn-up (pin average) Reference Zr Reflector Burn-up Limit Increase fuel burn-up 1st 2nd 3rd 3rd 4rd 5rd Maximum Linear Heat Rate [W/cm] Maximum liner heat rate Reference Zr Reflector Small Effect on Radial Distribution 1st 2nd 3rd 3rd 4rd 5rd Inner Core Outer Core Inner Core Outer Core Row Row 8

9 Changing the control rod arrangement Two experiences of changing the CR arrangement Good accuracy for calculation and Excess design margin Re-evaluate of the CR worth design margin Progress of Control rod arrangement Move CR Replace CR with Driver Fuel Move CR MK-III Core MK-II Driver Fuel Inner Driver Fuel Control Rod Materials Irradiation Rig MK-II Core Outer Driver Fuel Inner Reflector Fuel Irradiation Rig (type-b) Fuel Irradiation Rig (type-c) 9

10 Reduction of CR Design Margin based on the MK-III performance test C ontrolrod W orth [cents/ m m ] Differential rod worth profile Experim ental 0.2 C alculated Experim entalfit C ontrolrod Position [m m ] Measurement Error 3.2% No. Loc. C/E value of control rod worth Control Rod Worth [% k/kk'] Exp.(E) Biased calc. (C) C/E 1 3 rd 2.09± rd 2.03± rd 2.08± rd 2.06± th 0.80± th 0.78± Deviation of C/E (1σ) < ±1% < ±1% Reduce the calculation error in design margin Item Present This study Calculation error ± 13 % ± 5 % Larger deviation of C/E

11 Changing of refueling batch number To maximize the fuel burn-up within 5GWd/t (MK-II : 75GWd/t -> MK-III : 90GWd/t) CR arrangement 3 rd Row:4 5 th Row:2 3 rd Row :4 5 th Row :1 Number of Refueling(S/As) 9 Maximum Fast Neutron Flux (E>0.1 MeV)( 15 n/cm 2 s) Maximum burn-up [GWd/t] Maximum burn-up (pin average) Zr Reflector case1 Burn-up Limit 1st 2nd 3rd 3rd 4rd 5rd Maximum Linear Heat Rate [W/cm] Maximum liner heat rate Zr Reflector case1 Small Effect on Radial Distribution 1st 2nd 3rd 3rd 4rd 5rd Inner Core Outer Core Inner Core Outer Core Row MK-III MK-II Row 11

12 Effect on Flux distribution and CR worth Use as Safety Rod (Fully withdrawn in Operation) Fast Neutron Flux [n/cm 2 s] Change to Driver Fuel Zr Reflector 5 CR Core Distance from Core Center [cm] Radial Flux Distribution Small Increase at the position where CR replaced with driver fuel Control Rod Worth [% k/kk ] CR Zr Ref. Core 5 CR Core Criteria 3 rd th Total > 7.6 Decrease of CR Worth is less than % One Rod Stuck Margin [% k/kk ] Zr Ref. Core 5 CR Core Criteria > 1.1 No Significant effect on core characteristics 12

13 Summary Core modification was investigated to increase core and fuel burn-up of Joyo Installation of zirconium reflectors Changing the control rod arrangement Increase core and fuel burn-up up to 18% Reduce number of refueling up to 15% More irradiation experiments 13

14 Thank you for your attention! 14

15 Supplement 15

16 Background Irradiation test of which irradiation behavior is not well understood (MA bearing fuel, ODS cladding fuel, Metal fuel) One fuel pin is loaded in the high strength capsule that endures the pressure when the fuel is damaged. (Capsule type irradiation rig) The number of Irradiation test rig with little nuclear fuel increases. We remove driver fuel at low burn-up in order to compensate excess reactivity decrease. Compartment Capsule Fuel Pin for Examinations Need more fresh fuel (Fuel cost increases) Increase spent fuel (Lack of storage space) Fuel Pin for Examinations Shroud Tube Tie Rod Wrap tube Cross Section Capsule Inner Tube of Compartment Outer Tube of Compartment Capsule Type Irradiation Rig 16

17 Contents Introduction Core Modification Plan Installation of zirconium radial reflectors Changing the control rod arrangement Summary 17

18 Installation of zirconium reflectors Handling Head Inner Driver Fuel Outer Driver Fuel Inner Reflector Outer Reflector Shielding S/A Control Rod Fuel Irradiation Rig (type-b) Fuel Irradiation Rig (type-c) Joyo MK-III equilibrium 1/6 th core Reflector Element Wrapper Tube Spacer Pad Specification of radial reflector Subassembly length Reflector element length Reflector material 2970mm 650mm Modified 316SS, PNC1540, Zirconium alloy Number of elements 7 Volume ratio of the reflector material 70% Entrance Nozzle σσ absorption :Ni(0.030)> Zr(0.016) Fe(0.0) > Fe(0.011) Zr(0.008) a. unit:barn u. Σσ scattaring :Ni(6.6) > Zr(6.0) Fe(3.5) > Fe(3.7) Zr(2.8) unit:barn a. u. Mass num.:zr(91.2)> Ni(58.7) Fe(55.8) N. D. :Ni(1.0) Fe(0.94) > Zr(0.47) a. u. 18

19 Oarai research and development center Japan Materials Testing Reactor (JMTR) Alpha Gamma Facility(AGF) Fuels Monitoring Facility(FMF) Oarai center Monju Head Office & Tokai center Joyo Tokyo Office High Temperature engineering Test Reactor (HTTR) Joyo Advanced Nuclear System Research and Development Material Monitoring Facility (MMF) 19

20 Milestone of Joyo MK-I I C o re MK-I I I ~ Rated power operation First Criticality of MK-III Core MK-III Renovation Carbide and Nitride Fuel Irradiation(Cooperate with JAERI) Power-to-Melt Test(PTM) Fuel Failure Detection Test High Burnup Test (peak burnup of 144 GWd/t, Collaboration with CEA France) Served mainly as an Irradiation Facility for FBR Fuel and Material First Criticality of MK-II Core M K - I Cor e 1981 Natural Circulation Test Confirm Breeding Ratio Accumulate Technical Experience Through Planning, Construction and Operation Attain First Criticality 20

21 Objectives and Core Modification of MK-III Objectives of MK-III Upgrade Core modification for high neutron flux Control Rod Reflector Shielding Subassembl y Improvement of plant availability factor Irradiation capability enhanced 4 times Expansion of irradiation space Upgrade of irradiation techniques Irradiation Rig Fuel Subassembly Inner Fuel Subassembly MK-II Equilibrium Outer Fuel Subassembly MK-III Equilibrium Number of Fuel Subassemblies (Max.) Core Height Arrangement of Control Rods Stainless Reflectors in 9th and th Row Number of Irradiation Rigs (Max.) Fast Neutron Flux (E>0.1 MeV) Reactor Thermal Power cm 6 Control Rods in 3rd Row n/cm 2 /s 0 MW cm 4 Control Rods in 3rd Row 2 Control Rods in 5th Row Shielding S/A (B4C) n/cm 2 /s 140 MW 21

22 Heat transfer system Fuel Handling Machine Secondary Sodium Flow 1200t/h Air Flow 7700m 3 /min Loop B On-line Irradiation Rig Loop A 500 deg-c 470 deg-c 300 deg-c Primary Pump Secondary Pump Dump Heat Exchanger Core Reactor Vessel Intermediate Heat Exchanger 350 deg-c 1350t/h Primary Sodium Flow Liquid Metal Fast Reactor Thermal Power : 140MWt Coolant : Sodium Fuel : MOX 235 U : 18 wt% Pu Content : ~ 30wt% 22

23 Joyo is a Powerful Fast Neutron Irradiation Facility World s highest fast neutron field allows accelerated fuel and material irradiation tests Peak Fast Neutron Flux( 15 n/cm 2 s) Joyo MK-III MK-II BOR-60 (Russia) FBTR (India) CEFR (China) -Under Construction- (Experimental Reactor) Phenix (France) ~2008 MONJU BN-600 (Russia) (Proto Type Reactor) Reactor Thermal Power (MWt) 23

24 MK-Ⅲ J O Y O Effect of Zirconium Factor of increasing reactivity (1)Absorption Zr s neutron absorption is less than SS (2)Scattering Lower loss energy by elastic scattering than SS (3)Leakage Increasing neutron leakage ovew1mev and between kev 0.15 and 0keV(negative reactivity effect) Reactivity Change [%Δk/kk ] Absorptio n Scatterin g Leakage Total Experimental Result at FCA (Fast Criticality Assembly) Reactivity Change at FCA core center (SS Zr) Reactivity Change [%Δk/kk'] Corresponding to 3 fresh fuel Absorption Scattering Leakage (1) (2) (3) Neutron Energy [ev] Energy and Component wise reflector replacement reactivity (Calculated using PERKY) 24

25 Effect of Zirconium Reflector Fissile inventory (a. u.) Number of refueling Decrease of necessary inventory Installation of Zirconium Reflector 9 k eff =1 (SS Ref.) k eff =1 (Zry Ref.) Operation days Improve the neutron efficiency Decrease of necessary inventory = Long use of a driver fuel Increase of a burn-up of spent fuel Increase of reactivity change for one refueling Decrease of necessary number of refueling 25

26 Calculation Results (Zr Ref.) Radial Flux Distribution: Small Increase near Reflector First Neutron Flux [n/cm 2 s] Reference Zr Reflector Distance from the Core Center [cm] n/cm 2 s/lethargy lethargy] Neutron Flux [n/cm Small Effect on Neutron Spectrum Reference Zr Reflector 0 Neutron Energy [MeV] Control Rod Worth [% k/kk ] Pos. SUS Ref. Zr Ref. 3rd th No Significant effect on core characteristics 1 26

27 Core physics characteristics of zirconium reflector Item Reference Zr reflec Criteria tor Average number of fuel exchange Maximum linear heat rate [W/cm] Power peaking factor Inner Outer Total Radial Axial Local Maximum neutron flux [n/cm 2 s] Effect for Shielding S/A Maximum pin averaged fuel burn-up [GWd/t] Maximum S/A averaged fuel burn-up [GWd/t] Control rod worth [%Δk/kk'] * Equivalent to reach capture/cc B capture reaction rate [capture/cc s -1 ] Life time* [days] Inner Outer Inner Outer Average of 3 rd row Average of 5 th row Total More than

28 Control Rod Handling Head Vent aperture Vent pipe Sodium inflow pipe Wrapper Tube Control Element Neutron absorbent(b4c pellet) Lower Structure Shroud pipe 28

29 Calculation Results (CR arrangement) Zr Ref. Core Case 1 Case 2 Case 3 Case 4 Item 3 rd Row: 4 5 th Row: 2 3rd:4 5th:1 3rd:4 5th:0 3rd:2 5th:4 3rd:2 5th:2 Substitution Reactivity [% k/kk'] One Rod Stuck Margin* [% k/kk'] * More than 1.0 Present Design Margin Re-evaluate Design Margin 13 5% Case 1 was focused 5 th Row CR was used as safety rod (fully withdrawn in operation) 29

30 C ontrolrod W orth [cents/ m m ] No. Loc. Reduction of CR Design Margin based on the performance test Control Rod Worth [% k/kk'] Exp.(E) Base calc. Bias Factor Biased calc. (C) 1 3 rd 2.09± rd 2.03± rd 2.08± rd 2.06± th 0.80± th 0.78± Differential Rod Worth Profile Statistic Item Signal Swing of Nuclear Instruments Measurement Error of CR Position Correction Experim Error ental of 0.2 Shadow Effect C alculated Systematic 0.0 Error of β eff Experim entalfit C ontrolrod Position [m m ] Total Measurement Error 3.2% Error(%) Correction for base calculation Uncertainty in calculation C/E Item Present Modified C/E B decrease due to burnup 0.85 Core size change ±1 % Asymmetrical arrangement Design margin Fabrication tolerance of B 4 C Calculation error Deviation (1σ) <±1% <±1% ±2 % ±2 % ±13 % ±5 % Total ±18 % ± %

31 Core physics characteristics of control rod arrangement Item Zr Reflector Case 1 Case 2 3rd:4 rods 5th:2 rods 3rd:4 rods 5th:1 rod 3rd:4 rods 5th:0 rod Criteria Average number of fuel exchange Maximum linear heat rate [W/cm] Peaking factor Inner Outer Total Radial Axial Local Maximum neutron flux [n/cm 2 s] Effect on Shielding S/A Control rod worth [%Δk/kk'] B capture reaction rate [capture/cc s -1 ] One rod stuck margin at 0 o C [%Δk/kk'] Life time* [days] Average of 3 rd row Average of 5 th row * Equivalent to reach capture/cc Total More than More than

32 R&D items to increase Joyo driver fuel burn-up Item PIE of the MK-III driver fuel (Maximum pin averaged fuel burn-up: 86.0 GWd/t) Re-evaluation of mechanical design method of the MK-III driver fuel based on PIE Visual inspection X-ray CTscanning Pin profilometry Pin puncture test Metallography and Elemental analysis Design criteria for strength during short term stress Design equation New design to achieve 5 GWd/t (pin averaged) Defect Deformation Dimensional change Viewpoint FP gas release ratio - Corrosion by sodium at outer surface of cladding tube - Fuel cladding chemical interaction (FCCI) (current design criteria is based on the ASME code) - Sodium corrosion and FCCI - FP gas release ratio - Fuel pin and subassembly integrity - Evaluation of short term stress and CDF 32