Study on SiC Components to Improve the Neutron Economy in HTGR - - PowerPoint PPT Presentation

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May 15, 2023 324 likes •539 views

Study on SiC Components to Improve the Neutron Economy in HTGR Piyatida TRINURUK and Assoc.Prof.Dr. Toru OBARA Department of Nuclear Engineering Research Laboratory for Nuclear Reactors Tokyo Institute of Technology, Japan Contents

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SLIDE 1

Study on SiC Components to Improve the Neutron Economy in HTGR

Piyatida TRINURUK and Assoc.Prof.Dr. Toru OBARA Department of Nuclear Engineering Research Laboratory for Nuclear Reactors Tokyo Institute of Technology, Japan

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SLIDE 2

Contents

 Introduction  Objectives of this study  Computer code and Parametric survey  Results and discussions  Conclusions

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SLIDE 3

 HTGR : High Temperature Gas-cooled Reactor  A graphite-moderator and helium gas-cooled reactor.  HTTR (High Temperature Test Reactor): Prismatic

block type HTGR.

 Japan Atomic Energy Research Institute (JAERI) in

1996.

 Thermal output 30 MW.  Fuel blocks, control rod blocks, reflector blocks and

irradiation blocks.

 Uranium enrichments: 3.4 - 9.9%wt - U235

Introduction

Fuel compact Coated Fuel Particle Fuel block & Fuel rod

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SLIDE 4

Convention way to compensate the excess reactivity in HTTR

(Source: N.Fujimoto and et.al., Nuclear design, Nuclear Eng. and design 233 , 2004)

Pros.

 High output temperature  Inherent safety reactor

Cons.

 Once-through fuel cycle.  High excess reactivity.  Unavailable in commercial

technique for fuel reprocessing.

Introduction

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SLIDE 5

Properties of SiC

 SiC is a compound of silicon and carbon.  Silicon (Si):

  • Higher absorption cross section
  • Smaller scattering cross section
  • Higher mass number

 Disadvantage of SiC:

  • SiC decomposes at lower temperature as compared to IG-110

graphite.

  • SiC corrodes by Palladium (Pd).

Carbon Si-28

Source: http://wwwndc.jaea.go.jp

Poor moderating material compared to graphite

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SLIDE 6

Objectives

 To evaluate the use of SiC in various parts of fuel block

assembly instead of graphite to take the benefit of transmutation under the concept of neutron spectrum shifting.

Shifting the neutron spectrum Increase the conversion of fertile into fissile material More fission product by without increasing the U-235 enrichment

The neutron economy

Compensate reactivity and prolong fuel cycle

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SLIDE 7
  • MVP-2.0 : Continuous energy neutron transport Monte Carlo method
  • JENDL- 4.0 : Nuclear data library

Computer code and Parametric survey

  • II. Several fuel block assemblies
  • I. One fuel block assembly

Number of fuel rods / block 33 Burnable poison No Enrichment of fuel 5% wt of U235 Packing fraction 30% History / batch 30,000 Batch (Skips + tallies) 50+150 Boundary condition Periodic boundary Number of energy groups 176

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SLIDE 8

Parametric survey

Case Conditions Specification 1. Fuel compact material Graphite  SiC 2. Fuel sleeve material Graphite  SiC 3. Fuel block material Graphite  SiC 4. Combination between SiC block and GP block Based on 3 fuel blocks

4 1

Fuel compact

3

Fuel block

2

Fuel pin

Combination between SiC block & GP block

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SLIDE 9

Results and Discussions

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SLIDE 10
  • I. Effects of SiC on the neutron spectrum

Conditions:

 One fuel block assembly.  33 Fuel pins with 30% of packing fraction.  Enrichment : Natural Uranium, 5%, 10%, 20%.  SiC material : fuel compact / fuel sleeve / fuel block.  No burnable poison.

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SLIDE 11

0.0E+00 1.0E-03 2.0E-03 3.0E-03 4.0E-03 5.0E-03 1.0E-04 1.0E-01 1.0E+02 1.0E+05 Neutrom spectrum (n/s/cm3/Lethargy/sourc) Energy (eV)

SiC fuel block

  • Nat. U

SiC sleeve

  • Ref. case

SiC fuel compact

0.0E+00 1.0E-04 2.0E-04 3.0E-04 4.0E-04 5.0E-04 6.0E-04 7.0E-04 8.0E-04 1.0E-04 1.0E-01 1.0E+02 1.0E+05 Neutrom spectrum (n/s/cm3/Lethargy/sourc) Energy (eV)

SiC fuel block

En.10%

SiC sleeve

  • Ref. case

SiC fuel compact

0.0E+00 1.0E-04 2.0E-04 3.0E-04 4.0E-04 5.0E-04 6.0E-04 7.0E-04 8.0E-04 1.0E-04 1.0E-01 1.0E+02 1.0E+05 Neutrom spectrum (n/s/cm3/Lethargy/sourc) Energy (eV)

SiC fuel block

En.20%

0.0E+00 2.0E-04 4.0E-04 6.0E-04 8.0E-04 1.0E-03 1.2E-03 1.4E-03 1.6E-03 1.0E-04 1.0E-01 1.0E+02 1.0E+05 Neutrom spectrum (n/s/cm3/Lethargy/sourc) Energy (eV)

SiC fuel block

  • Ref. case

SiC fuel compact SiC sleeve

En.5%

  • I. Effects of SiC on the neutron spectrum
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SLIDE 12

0.00 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 5,000 10,000 15,000 20,000 25,000 30,000 Infinite multiplication factor MWD/Ton

SiC fuel block

0.00 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 5,000 10,000 15,000 20,000 25,000 30,000 Infinite multiplication factor MWD/Ton

En.10%

0.00 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 5,000 10,000 15,000 20,000 25,000 30,000 Infinite multiplication factor MWD/Ton

En.20%

0.00 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 5,000 10,000 15,000 20,000 25,000 30,000 Infinite multiplication factor MWD/Ton

  • II. Effects of SiC on the reactivity
  • Nat. U

En.5%

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SLIDE 13

0.0E+00 2.0E-04 4.0E-04 6.0E-04 8.0E-04 1.0E-03 1.2E-03 1.4E-03 10,000 20,000 30,000 Nuclide density MWD/Ton

U235

2.14E-02 2.15E-02 2.16E-02 2.17E-02 2.18E-02 2.19E-02 2.20E-02 2.21E-02 10,000 20,000 30,000 Nuclide density MWD/Ton

U238

2.20E-02 2.22E-02 2.24E-02 2.26E-02 2.28E-02 2.30E-02 2.32E-02 10,000 20,000 30,000 Nuclide density MWD/Ton

U238

0.0E+00 2.0E-05 4.0E-05 6.0E-05 8.0E-05 1.0E-04 1.2E-04 1.4E-04 1.6E-04 1.8E-04 10,000 20,000 30,000 Nuclide density MWD/Ton

U235

0.00E+00 5.00E-05 1.00E-04 1.50E-04 2.00E-04 2.50E-04 10,000 20,000 30,000 Nuclide density MWD/Ton

Pu239

0.00E+00 1.00E-05 2.00E-05 3.00E-05 4.00E-05 5.00E-05 6.00E-05 7.00E-05 8.00E-05 10,000 20,000 30,000 Nuclide density MWD/Ton

Pu241

0.00E+00 5.00E-05 1.00E-04 1.50E-04 2.00E-04 2.50E-04 10,000 20,000 30,000 Nuclide density MWD/Ton

Pu239

0.00E+00 5.00E-06 1.00E-05 1.50E-05 2.00E-05 2.50E-05 3.00E-05 3.50E-05 4.00E-05 4.50E-05 10,000 20,000 30,000 Nuclide density MWD/Ton

Pu241

Enrichment : Natural Uranium Enrichment : 5%

  • III. Effects on the change of nuclide density
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SLIDE 14

2.0E-03 2.5E-03 3.0E-03 3.5E-03 4.0E-03 4.5E-03 5.0E-03 10,000 20,000 30,000 Nuclide density MWD/Ton 1.82E-02 1.83E-02 1.83E-02 1.84E-02 1.84E-02 1.85E-02 1.85E-02 1.86E-02 1.86E-02 10,000 20,000 30,000 Nuclide density MWD/Ton

U238

0.00E+00 5.00E-05 1.00E-04 1.50E-04 2.00E-04 2.50E-04 10,000 20,000 30,000 Nuclide density MWD/Ton

Pu239

0.00E+00 2.00E-06 4.00E-06 6.00E-06 8.00E-06 1.00E-05 1.20E-05 10,000 20,000 30,000 Nuclide density MWD/Ton

Pu241

Enrichment : 20% (HEU)

U235

  • III. Effects on the change of nuclide density
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SLIDE 15
  • Using SiC in HTTR instead of graphite can make the

spectrum harden.

  • The benefit of transmutation by the shift of neutron

spectrum is more effective for LEU because SiC can slow down the depletion of fissile nuclide as U-235 and increase the utilization of fertile nuclide U-238.

  • The magnitude of the spectrum shifting depends on the

ratio of graphite which is replaced with SiC.

64.30% 14.22% 17.85% 3.63%

Fuel block Fuel compact Fuel Sleeve Coating layer

The percent of graphite volume of each component in a fuel block

Effects of SiC in each component

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SLIDE 16
  • IV. Combination of SiC blocks & graphite blocks

Condition:

  • 5 % enriched uranium
  • 3 fuel blocks

All graphite blocks GP : SiC blocks = 2 : 1 GP : SiC blocks = 1 : 2 All SiC blocks

0.30 0.40 0.50 0.60 0.70 0.80 0.90 1.00 1.10 1.20 1.30 1.40 1.50 10,000 20,000 30,000 40,000 50,000 60,000 70,000

Infinite multiplication factor MWD/Ton

  • Increase the ratio of SiC blocks in the core can compensate

the excess reactivity and flatten the reactivity.

  • SiC block results into the reactor operated under the

criticality.

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SLIDE 17
  • V. Improvement of reactivity in SiC block
  • Increase the fuel enrichment in SiC block can success to

improve the reactivity and make the reactor operate at the criticality.

0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 10,000 20,000 30,000 40,000 50,000 60,000

Infinite multiplication factor MWD/Ton

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SLIDE 18

Conclusions

  • SiC has a potential to make the neutron spectrum harden

and increase the fissile material by the transmutation.

  • The magnitude of spectrum shifting depends on the ratio
  • f SiC replacement : more SiC, more effective to harden

spectrum.

  • LEU and HEU under the harden spectrum can perform as

burnable poison to compensate the excess reactivity, but it will lead the reactor operated under the critical.

  • The optimization between the ratio of SiC replacement

and the fuel enrichment is need to pay attention in order to achieve the neutron economy.

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SLIDE 19

Thank you for your kind attention