Naofumi Nakazato, Hirotatsu Kishimoto, Naoyuki Takayama, Joon

Naofumi Nakazato, Hirotatsu Kishimoto,
Naoyuki Takayama, Joon-Soo Park and Akira Kohyama
Introduction
OASIS (Organization of Advanced Sustainability Initiative for Energy System/Material),
Muroran Institute of Technology, Japan
OASIS, Muroran Institute of Technology is conducting joint researches for R & Ds of accident tolerant fuel (ATF) with International Research Center for Nuclear
Materials Science (Oarai center), Institute for Materials Research (IMR), Tohoku University. One of the joint research programs is neutron irradiation effects of NITESiC/SiC composites at research reactors such as JMTR, JOYO and BR2. Up to now, neutron irradiation study of NITE-SiC/SiC composites has been done by
laboratory-scale materials. Furthermore, R & Ds of DEMO-NITE process are on-going at OASIS. The “DEMO-NITE process” is modified original-NITE process
toward industrialization, which utilizes dry type inter-mediate materials such as green-sheets, prepreg sheets and pre-composite ribbon (PCR). However, irradiation
effects database of SiC/SiC composites by DEMO-NITE process is insufficient. In order to realize early commercialization of NITE-SiC/SiC composites to light water
reactor (LWR), accumulation of irradiation effects data is necessary.
Background
Experimental Procedure
●Joint research for R & Ds of ATF with IRCNS, Tohoku University
●Irradiation conditions;
Reactor : BR2
Capsule : BAMI
Temperature : <100℃
Atmosphere:
Water
Neutron fluence :
2 x 1024 n/m2
Estimate damage of SiC/SiC
composites : 0.2 dpa
 Recently joint researches programs ;
JFY 2013
Basic Properties and Irradiation Effects of NITE-SiC/SiC Cladding Tubes
Microstructure and Irradiation Effects of NITE-SiC/SiC Composites for Fission
Reactor
JFY 2014
Mechanical Properties and Irradiation Effects of NITE-SiC/SiC Cladding Tubes
Effects of Neutron Irradiation on Mechanical Properties of NITE-SiC/SiC
Composites for Fission Reactor
●BR2 irradiation plan
●Tensile test conditions;
Specimen type :
Dog-born type
Specimen size :
40L x 4W x 1.5T mm
Gauge length : 15 mm
Gripping sections :
Bonded Aluminum tabs
Strain measurement :
A couple of strain gauge
Crosshead speed : 0.5 mm
Results
●Mechanical properties of DEMO-NITE-SiC/SiC composites before irradiation
●Outline of “DEMO-NITE” process
 “DEMO-NITE” process is a new NITE process toward industrialization, which was
developed by OASIS, Muroran Institute of Technology, Japan.
 The feature of this process is to use polymer based slurry for making dry type
inter-mediate materials, such as green-sheets, prepreg sheets and precomposites ribbon.
 In the OASIS, construction of pilot plant for production of SiC/SiC composites are
currently ongoing.
 The ultimate tensile strength (UTS) of the single layer and the multi layer is 234
MPa and 161 MPa, respectively.
 Both of specimens are indicated a little pseudo-ductility fracture behavior.
 In the fracture surface of the single layer, short fiber pull-outs and crack
deflections in the fiber bundles were observed.
 In the fracture surface of the multi layer, large crack deflections were observed in
between of monolithic SiC layer and SiC/SiC layer. Also, short fiber pull-outs were
seen.
●Mechanical properties of DEMO-NITE-SiC/SiC composites after irradiation
Objective
The objective of this study is to demonstrate soundness of DEMO-NITE-SiC/SiC
composites under LWR environment. The preliminary PIE results of the specimens
from the JFY 2012 irradiation are presented.
Experimental Procedure
●Materials
●Through-thickness Cross-section
●Specimen dimension
 The multi layer specimen has monolithic
SiC coating to SiC/SiC composites
surface,
which
has
excellent
environmental resistance structure.
Conclusion
 The UTS after irradiation of the single layer and the multi layer is 226 MPa and 169
MPa, respectively.
 The significant degradation of the UTS by irradiation is not seen in the both of
specimens. This result suggests soundness of NITE-SiC/SiC composites under
this irradiation condition.
 The significant change on fracture surface by irradiation was not observed in the
preliminary PIE.
As preliminary soundness evaluation of DEMO-NITE-SiC/SiC composites under LWR environment, mechanical properties after BR2 irradiation were tested at Oarai
center, Tohoku University. The fracture behavior observed before irradiation was as usual with sufficient fiber pull-outs. Also, even after irradiation at BR2, no clear
change on mechanical behavior, including UTS, was seen. From this preliminary PIE results, the soundness of NITE-SiC/SiC composites was suggested under this
irradiation condition. The on-going irradiation may bring more clear irradiation effect information on the SiC/SiC composites.