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Draft standard was already issued by special committee of AESJ (Atomic Energy Society of Japan) (*1)
Composition of draft standard1. General rules2. Design standard for graphite components of HTGR3. Material and product standard for graphite components of HTGR4. In-service inspection and maintenance standard for graphite components of HTGR
Stress limit and consideration of oxidation ,etc. in draft standard
Reasonable interpolation and extrapolation method in draft standard
(*1) “Special committee on research on preparation for codes for graphite components in HTGR” (2008.4- 2009.3) Chair: T. Maruyama, Vice-chair: T. OkuReference : Expansion of Irradiation Data by Interpolation and Extrapolation for Design of Graphite Components in High Temperature Gas-cooled Reactor, JAEA-Research 2009-008
‘ Draft of standard for graphite core components in HTGR ’ (JAEA-Research 2009-042. English version)
IG-110 graphite meets the technical criteria decided in the standard.
Material property data on IG-110 graphite (including irradiation effects ) are listed in the standard.
In the draft standard the interpolation and extrapolation of the design data on IG-110 graphite are carried out, but that should be verified.
For that purpose, Toyo Tanso has started to irradiate IG-110 and IG-430 graphite, a promising candidate for the future reactor, at high temperatures to the higher fluence in the HFIR at ORNL .
In the VHTR as a proven reactor operation conditions would be much more severe than those in the HTTR. Therefore, we need to expand the exiting irradiation data to the higher fluence region.
2. Irradiation schedule -- Irradiation plan in the HFIR --
Irradiation temperature : 300--1000ºC Neutron fluence : Area shown in the following figure Properties to be measured : Dimensions, Young’s modulus, CTE, etc. Grade : IG-110 and IG-430
3 . Irradiation behavior of IG-110 graphite -- Dimensional Change and Dose-Effect Curve --
Dimensional Change of IG-110 graphite with Irradiation and Dose-Effect Curve Obtained by Interpolation and Extrapolation
Reference(1) : Expansion of Irradiation Data by Interpolation and Extrapolation for Design of Graphite Components in High Temperature Gas-cooled Reactor, JAEA-Research 2009-008
・ The results are consistent with the dose-effect curve.・ About the irradiation data in high-temperature ranges, the temperature is checking now. We will review the results when more data is accumulated.
3 . Irradiation behavior of IG-110 graphite -- Young's Modulus Change and Dose-Effect Curve --
Young's Modulus Change of IG-110 graphite with Irradiation and Dose-Effect Curve Obtained by Interpolation and Extrapolation
・ Irradiation increases Young's modulus.・ The results at 400ºC are consistent with the dose-effect curve.・ The data obtained at 600ºC show rates of increase higher than the dose-effect curve.
We will review the results when more data is accumulated.
E0 : Young’s modulus of un-irradiated IG-110 graphite
E : Young’s modulus of irradiated IG-110 graphiteDose-Effect Curve
Dimensional change of irradiated IG-430 and IG-110 graphite
・ Both IG-430 and IG-110 graphite show similar behavior under low fluence region.・ Some reports indicates that fluence of a turnaround point of IG-430 is lower than
that of IG-110. We will review the results when more data in high temperature / high fluence region is accumulated.
Error bar indicate on standard deviation Error bar indicate on standard deviation
Irradiation effect on thermal conductivity of IG-430 and IG-110 graphite
・ After irradiation, the thermal conductivity of both IG-430 and IG-110 graphite decreases.・ Comparing with IG-110 graphite, IG-430 graphite shows a smaller decrease in thermal conductivity with the same irradiation.
1. The comparison between irradiation data of IG-110 and dose-effect curve. The results of irradiation on IG-110 graphite in low-temperature
ranges show good agreement with the dose-effect curve established in the draft standard.
For high temperature ranges, we will verify consistency of the dose-effect curve by more data is accumulated.
After all irradiation data is obtained, the dose-effects curve will be optimized.
2. The irradiation behavior of IG-430 and IG-110 graphite in low temperature / low fluence region is compared as follows: The changes in dimensions and Young's modulus are similar. The change of the IG-430’ thermal conductivity shows a smaller
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