AGC-2 Specimen Post Irradiation Data Package Report

Abstract

This report documents results of the post-irradiation examination material property testing of the creep, control, and piggyback specimens from the irradiation creep capsule Advanced Graphite Creep (AGC)-2 are reported. This is the second of a series of six irradiation test trains planned as part of the AGC experiment to fully characterize the neutron irradiation effects and radiation creep behavior of current nuclear graphite grades. The AGC-2 capsule was irradiated in the Idaho National Laboratory Advanced Test Reactor at a nominal temperature of 600°C and to a peak dose of 5 dpa (displacements per atom). One half of the creep specimens were subjected to mechanical stresses (an applied stress of either 13.8, 17.2, or 20.7 MPa) to induce irradiation creep. All postirradiation testing and measurement results are reported with the exception of the irradiation mechanical strength testing, which is the last destructive testing stage of the irradiation testing program. Material property tests were conducted on specimens from 15 nuclear graphite grades using a similar loading configuration as the first AGC capsule (AGC-1) to provide easy comparison between the two capsules. However, AGC-2 contained an increased number of specimens (i.e., 487 total specimens irradiated) and replaced specimens of the minor grade 2020 with the newer grade 2114. The data reported include specimen dimensions for both stressed and unstressed specimens to establish the irradiation creep rates, mass and volume data necessary to derive density, elastic constants (Young's modulus, shear modulus, and Poisson's ratio) from ultrasonic time of flight velocity measurements, Young's modulus from the fundamental frequency of vibration, electrical resistivity, and thermal diffusivity and thermal expansion data from 100-500°C. No data outliers were determined after all measurements were completed.A brief statistical analysis was performed on the irradiated data and a limited comparison between pre-and post-irradiation properties is presented. A more complete evaluation of trends in the material property changes, as well as irradiation-induced creep due to irradiation, temperature, and applied load on specimens will be discussed in later AGC-2 post-irradiation examination analysis reports.

AGC 2 Irradiated Material Properties Analysis

“…Post irradiation material property data are provided in AGC-2 Specimen Post-Irradiation Data Package Report (INL/EXT-15-36244). 9 An uncertainty analysis on material property measurements can be found in AGC Inter-laboratory Comparison of Graphite Testing Procedures (TEV-2530). 37 Table 3 shows the breakdown of specimens in the AGC-2 capsule by graphite grade, grain orientation, and specimen type.…”

“…The more familiar thermal conductivity is derived from diffusivity values by multiplying thermal diffusivity by the material density and specific heat capacity: K = αρC p (9) where: K = thermal conductivity α = thermal diffusivity ρ = density C p = specific heat.…”

AGC 2 Irradiation Creep Strain Data Analysis

“…This report is an AGC PIE analysis report on irradiation-induced creep strain within the second AGC capsule (AGC-2). Data from the "AGC-2 Specimen Post-Irradiation Data Package Report" 4 was used to analyze the dimensional strain data in order to calculate the corresponding creep strain and creep coefficients for each graphite grade. An analysis of the irradiation material property changes (electrical resistivity, thermal diffusivity, coefficient of thermal expansion, stiffness, and strength) will be provided within a future PIE analysis report.…”

“…Dimensional change (strain) data for all major graphite grades are provided in INL's "AGC-2 Specimen Post-Irradiation Data Package Report". 4 The total specimen irradiation dose, average irradiation temperature, and applied mechanical load during irradiation for each specimen are recorded along with the dimensional change measurements. Total volumetric, length, and diametric dimensional AGC-2 specimen changes are summarized in Figure 5 through Figure 7 for the control specimens and three applied mechanical load states.…”

Characterisation of the spatial variability of material properties of Gilsocarbon and NBG-18 using random fields

“…For this research a billet of this grade was sectioned into 770 specimens that were used to measure the density, compressive strength, tensile strength, Young's modulus, shear modulus and other mechanical properties. The mechanical performance of this graphite grade under irradiation is also currently being investigated under the Advanced Graphite Creep programs (AGC) AGC-1 [28] and AGC-2 [29].…”