Standard Practice for Testing Graphite Materials for Gas-Cooled Nuclear Reactor Components

Importancia y uso:

4.1 Property data obtained with the recommended test methods identified herein may be used for research and development, design, manufacturing control, specifications, performance evaluation, and regulatory statutes pertaining to nuclear reactors that utilize graphite.

4.2 The referenced test methods are applicable primarily to specimens in the non-irradiated and non-oxidized state. Testing irradiated specimens often requires specimen geometries that do not meet the requirements of the standard. Specific instructions or recommendations with respect to testing non-conforming geometries can be found in STP 15784 and/or Guide D7775. When testing irradiated specimens at elevated temperatures, the effects of annealing should be considered (see Note 1).

Note 1: Exposure to fast neutron radiation will result in atomic and microstructural changes to graphite. This radiation damage occurs when energetic particles, such as fast neutrons, impinge on the crystal lattice and displace carbon atoms from their equilibrium positions, creating a lattice vacancy and an interstitial carbon atom. The lattice strain that results from displacement damage causes significant structural and property changes in the graphite and is a function of the irradiation temperature and dose. When the temperature of the graphite is brought above the temperature at which it was irradiated, enough energy is provided that the structure of the graphite will anneal back to its original condition. Therefore, measurement techniques that bring the specimen temperature above the irradiation temperature can result in property values that change during the measurement process. For this reason, measurements made on irradiated test specimens below the irradiation temperature will produce results that are representative of the irradiation damage. However, measurements made at temperatures above the irradiation temperature could include the effects of annealing.

4.3 Additional test methods are in preparation and will be incorporated. The user is cautioned to employ the latest revision.

Subcomité:

D02.F0

Referida por:

D7301-21, D7219-19, C0714-23, D7846-21

Volúmen:

05.05

Número ICS:

27.120.10 (Reactor engineering)

Palabras clave:

chemical properties; graphite; gas-cooled nuclear reactors; mechanical properties; neutronic properties; physical properties; thermal properties;