Effects of High Temperature Neutron Irradiation on Dimension and Thermal Expansion Coefficient of Nuclear Grade Graphites

Abstract

This paper describes the experimental results and discussions on the changes in dimension, volume and thermal expansion coefficient of five nuclear grade graphites which were made from petroleum coke or gilsonite coke and irradiated in the JMTR a t 670--1,26O0C UP to the maximum neutron fluence 3.3 x lo2' n/cm2 (E>0.18 MeV).Dimensional or volume shrinkages for all samples were observed after irradiation and their changes depended on the kind of graphite studied. T h e changes in thermal expansion coefficient were also observed for three of five samples.The relations between the changes in dimension or volume and thermal expansion coefficient were obtained, and it was clarified that both the rates of irradiation shrinkage in dimension and volume of the sample having larger thermal expansion coefficient were smaller than for the sample having smaller thermal expansion coefficient.

Property changes of G347A graphite due to neutron irradiation

“…Newer data from the INNOGRAPH/ARCHER irradiation program has been investigating the dimensional changes that occur in multiple iso-molded grades (grade is not reported) [35]. The 600°C and 750°C low-fluence IG-110 results from Matsuo et al [32,34], and the 750°C results from INNOGRAPH/ARCHER [35] irradiations agree well with the G347A volume change for the high temperature regimes. The agreement of the results from this work and measurements on other grades is shown in Figure 16.…”

“…Little data is available regarding the neutron irradiation-induced changes in other fine-grained nuclear graphite grades. The only fine-grained grade that has been studied to fluences that are similar to this work is IG-110 [15,[32][33][34]. The earliest research was performed on IG-11, the non-purified precursor grade to IG-110 [33], and was shortly followed by an investigation of IG-110 [32,34].…”

“…The only fine-grained grade that has been studied to fluences that are similar to this work is IG-110 [15,[32][33][34]. The earliest research was performed on IG-11, the non-purified precursor grade to IG-110 [33], and was shortly followed by an investigation of IG-110 [32,34]. The primary focus of these studies were for use in the High Temperature Test Reactor (HTTR), hence most of the irradiation temperatures were above 575°C [32], 1000°C [33], and 800°C [34].…”

“…The earliest research was performed on IG-11, the non-purified precursor grade to IG-110 [33], and was shortly followed by an investigation of IG-110 [32,34]. The primary focus of these studies were for use in the High Temperature Test Reactor (HTTR), hence most of the irradiation temperatures were above 575°C [32], 1000°C [33], and 800°C [34]. These experiments were also low fluence with values that approached levels of 7.5x10 25 [34].…”

“…The primary focus of these studies were for use in the High Temperature Test Reactor (HTTR), hence most of the irradiation temperatures were above 575°C [32], 1000°C [33], and 800°C [34]. These experiments were also low fluence with values that approached levels of 7.5x10 25 [34]. The only work that has approached temperature and fluence levels that are similar to this work was irradiations performed at ORNL in the late 1980's [15], where the nominal design temperature was 600°C with a maximum damage of 25 dpa.…”