ASTM D8377-2021 pdf free download

ASTM D8377-2021 pdf free download.Standard Guide for High Temperature Strength Measurements of Graphite Impregnated with Molten Salt
3. Summary of Guide
3.1 There is currently a set of ASTM standards as stated in 2.1 that can be applied to graphite for different strength measurements (Test Methods C651, C695, C749, D8289). Each of these standards has been developed specifically to provide a method of measurement for graphite as a single material. However, in some applications such as in molten salt reactors, graphite components are submerged in a molten salt. In order to assess the effect of molten salt on graphite components, a method may be necessary for the measurement of strength for graphite specimens both impregnated with molten salt and at elevated temperatures (see Section 4). The objective of this guide is to provide advice on the application of selected standards for graphite specimens impregnated with molten salt and tested at elevated temperatures. This includes transportation of graphite specimens impregnated with molten salt, temperature measurement, equipment for measuring compressive, tensile, or flexural strength at elevated temperature, and safe handling of the molten salt.
4. Significance and Use
4.1 The Molten Salt Reactor is a nuclear reactor which uses graphite as reflector and structural material, and molten salt as coolant. The graphite components will be submerged in the molten salt during the lifetime of the reactor. The porous structure ofgraphite may lead to molten salt permeation, which can affect the thermal and mechanical properties of graphite. Consequently, it may be necessary to measure the various strengths of the manufactured graphite materials after impreg- nation with molten salt and before exposure to the reactor environment in a range of test configurations in order for designers or operators to assess their performance.4.2 For gas-cooled reactors, the strength of a graphite specimen is usually measured at room temperature. However, for molten salt reactors, the operating temperature of the reactor must be higher than the melting temperature of the salt, and so the salt will be in solid state at room temperature. Consequently, room temperature measurements may not be representative of the performance of the material at its true operating conditions. It is therefore necessary to measure the strength at an elevated temperature where the salt is in liquid form. Users should also be aware that a small increase in graphite strength is expected with increasing temperature, and testing at the plant operating temperature will eliminate this small uncertainty. 4.3 The purpose of this guide is to provide considerations, which should be included in testing graphite specimens im- pregnated with molten salt at elevated temperature. 4.4 For the test results to be meaningful, the test material must have been impregnated at the reactor operating tempera- ture of interest and the strength measurement conducted at the same temperature following the guide here. The user must consider the effect of interaction between graphite and impreg- nated salt on the representativeness of the strength test based upon the heating and cooling stages between impregnation and testing.
5. Test Specimen Preparation
5.1 The specimen shape and size should be prepared in accordance with the corresponding ASTM standard listed in 2.1 for the desired test configuration (compressive, tensile, or flexural strength measurement). 5.2 The test specimen should then be impregnated with molten salt according to Guide D8091. 5.3 After impregnation, test specimens should be stored at room temperature in a glove box with a water content of less than 1 ppm. 5.4 Hermetic containers should be placed inside the glove box for specimen transfer or movement. The specimen should be placed within a hermetic container when moved from the glove box to a testing machine.