Irradiation creep of graphite

Conference · Mon Jan 01 04:00:00 EST 1990

OSTI ID:6892929

Kennedy, C R

Displacement damage of graphite by neutron irradiation causes graphite to change dimensions. This dimensional instability requires careful attention when graphite is used as as moderator and reflector material in nuclear devices. Natural gradients in flux and temperature result in time-varying differential growth generating stresses similar to thermal stresses with an ever increasing temperature gradient. Graphite, however, does have the ability to creep under irradiation, allowing the stress intensity to relax below the fracture strength of the material. Creep strain also serves to average the radiation-induced strains, thus contributing to the stability of the core. As the dimensional instability is a function of temperature, so are the creep characteristics of graphite, and it is of interest to generalize the available data for extension to more extreme conditions of fluence and temperature. Irradiation creep of graphite is characterized by two stages of creep; a primary stage that saturates with time and a secondary stage that is generally assumed to be linear and constant with time. Virtually all past studies have not considered primary creep in detail primarily because there is limited available data at the very low fluences required to saturate primary creep. It is the purpose of this study to carefully examine primary creep in detail over the irradiation temperature range of 150 to 1000{degree}C. These studies also include the combined effects of creep, differential growth, and structural changes in graphite by irradiation. 3 refs., 5 figs.

• Research Organization: Oak Ridge National Lab., TN (USA)
• Sponsoring Organization: DOE/NE
• DOE Contract Number: AC05-84OR21400
• OSTI ID: 6892929
• Report Number(s): CONF-901178-1; ON: DE90015545
• Country of Publication: United States
• Language: English

Related Subjects

22 GENERAL STUDIES OF NUCLEAR REACTORS
220200* -- Nuclear Reactor Technology-- Components & Accessories
36 MATERIALS SCIENCE
360603 -- Materials-- Properties
360605 -- Materials-- Radiation Effects
CARBON
CREEP
DEFORMATION
ELEMENTAL MINERALS
ELEMENTS
ENRICHED URANIUM REACTORS
GRAPHITE
MATERIALS
MATERIALS TESTING
MATHEMATICAL MODELS
MECHANICAL PROPERTIES
MINERALS
NONMETALS
ORR REACTOR
PHYSICAL RADIATION EFFECTS
RADIATION EFFECTS
REACTOR MATERIALS
REACTORS
TANK TYPE REACTORS
TEMPERATURE EFFECTS
TESTING
WATER COOLED REACTORS
WATER MODERATED REACTORS