ORNL/TM-2007/168 Revision 1

Assessment of Silicon Carbide Composites for Advanced Salt-

Cooled Reactors

Y. Katoh, D.F. Wilson, C.W. Forsberg Oak Ridge National Laboratory

September 2007

This report was prepared as an account of work sponsored by an agency of the United States Government. Neither the United States government nor any agency thereof, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise, does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States Government or any agency thereof. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States Government or any agency thereof.

ORNL/TM-2007/168

Assessment of Silicon Carbide Composites for Advanced Salt-Cooled Reactors

Y. Katoh*, D.F. Wilson, C.W. Forsberg Oak Ridge National Laboratory

Oak Ridge, Tennessee

Contributors

Lance L. Snead and David F. Williams Oak Ridge National Laboratory

Oak Ridge, Tennessee

Date Published: September 2007

Prepared by OAK RIDGE NATIONAL LABORATORY

Oak Ridge, Tennessee 37831 managed by

UT-BATTELLE, LLC for the

U.S. DEPARTMENT OF ENERGY under contract DE-AC05-00OR22725

* P.O.Box 2008, Oak Ridge, TN 37831-6138, Tel. (865) 576-5996, Email: katohy@ornl.gov

iii

CONTENTS

Page

LIST OF TABLES ...................................................................................................................... viiABBREVIATIONS AND ACRONYMS .................................................................................... ixABSTRACT .................................................................................................................................. xiEXECUTIVE SUMMARY ....................................................................................................... xiii1 INTRODUCTION .................................................................................................................. 1

1.1 BASIS FOR STUDY ....................................................................................................... 1

1.2 BASIS FOR SiC EVALUATION .................................................................................... 3

2 SiC FOR NUCLEAR APPLICATIONS ................................................................................ 7

2.1 FABRICATION TECHNIQUES ..................................................................................... 7

2.1.1 Composite fabrication ............................................................................................... 7

2.1.2 Shaping ................................................................................................................... 11

2.1.3 Joining ..................................................................................................................... 13

2.1.4 Coating .................................................................................................................... 14

2.2 FIBER AND ARCHITECTURE ................................................................................... 14

2.3 INTERFACE / INTERPHASE DESIGN ....................................................................... 16

2.4 PROPERTIES ................................................................................................................ 19

2.4.1 Flexural strength ..................................................................................................... 20

2.4.2 Tensile strength ....................................................................................................... 21

2.4.3 Thermal conductivity .............................................................................................. 23

2.4.4 Lifetime properties .................................................................................................. 25

2.4.5 Anisotropy of properties ......................................................................................... 27

2.4.6 Properties of NITE SiC/SiC .................................................................................... 28

2.5 RADIATION EFFECT .................................................................................................. 29

2.5.1 Radiation effect on strength of pure SiC ................................................................. 29

2.5.2 Radiation effect on strength of SiC/SiC .................................................................. 33

2.5.3 Thermal conductivity .............................................................................................. 36

2.5.4 Radiation-induced swelling and microstructure ..................................................... 38

2.5.5 Irradiation Creep ..................................................................................................... 42

2.5.6 Summary of radiation effect issues ......................................................................... 44

iv

CONTENTS (continued)

Page

2.6 TEST STANDARDS AND NON-DESTRUCTIVE EVALUATION .......................... 45

2.7 ONGOING PROGRAMS .............................................................................................. 47

2.7.1 Fusion ...................................................................................................................... 48

2.7.2 NGNP / VHTR ........................................................................................................ 51

2.7.3 GFR ......................................................................................................................... 55

2.7.4 Advanced LWR cladding ........................................................................................ 58

3 SiC/SiC FOR AHTR: ANALYSIS OF ISSUES .................................................................. 59

3.1 AHTR STRINGER FUEL COMPONENTS AND REQUIREMENTS ........................ 60

3.1.1 Fuel cladding ........................................................................................................... 60

3.1.2 Other fuel assembly components ............................................................................ 61

3.1.3 Reaction control system .......................................................................................... 61

3.2 FABRICATION ............................................................................................................. 62

3.2.1 Fuel rod cladding .................................................................................................... 62

3.2.2 Other fuel assembly components ............................................................................ 63

3.2.3 Control rod .............................................................................................................. 63

3.3 CORROSION ................................................................................................................. 64

3.4 MECHANICAL INTEGRITY ....................................................................................... 67

3.5 RADIATION EFFECTS ................................................................................................ 67

3.6 COATING ...................................................................................................................... 70

3.7 TEST STANDARDS AND DESIGN CODIFICATION............................................... 71

4 PATH-FORWARD ............................................................................................................... 73

4.1 CORROSION OF SIC IN LIQUID SALTS .................................................................. 76

4.2 PROTOTYPICAL DEMONSTRATION ...................................................................... 77

4.3 EFFECTS OF HIGH DOSE IRRADIATION ON FUNDAMENTAL PROPERTIES OF SIC/SIC ............................................................................................................................... 77

REFERENCES ............................................................................................................................ 81

v

LIST OF FIGURES

Figure Page

Figure 1: Examples of components fabrication with CVI SiC/SiC. Left: Tensile test specimens of small diameter, thin wall tubes.(ORNL Gen-IV Materials Program) Right: Rocket nozzle (Courtesy: Hypertherm High-Temperature Composites, Inc.) ..................................................... 11

Figure 2: Examples of components fabrication with NITE SiC/SiC (Courtesy: Kyoto University)....................................................................................................................................................... 12

Figure 3: Influences of pyrocarbon interphase thickness on mechanical properties of CVI SiC/SiC composites. [45-46] ........................................................................................................ 18

Figure 4: Flexural properties of CVI SiC/SiC. [48] ...................................................................... 21

Figure 5: Examples of tensile stress-strain behavior of CVI SiC/SiC (testing procedure