THE EFFECT OF A TENSILE RESTRAINT ON GRAPHITE SPECIMENS IRRADIATED IN BR-2

Technical Report · Fri Jul 01 04:00:00 EDT 1966

OSTI ID:4463982

Brocklehurst, J E; McFarlane, A A; Gray, B S

The ability of graphite to absorb strain by plastic deformation under irradiation is important to the design of the core in graphite moderated reactors, as it determines the extent of self-stressing due to the differential irradiation growth caused by flux and temperature gradients. Specimens of near-isotropic graphites, in the form of rings restrained from shrinking at the inner bore by a mandrel have been irradiated in BR-2, at about 400 deg C. The net specimen strain rate depended on the rate of irradiation-induced shrinkage and the temperature changes during each reactor cycle. It is shown that at least 0.6% plastic strain may be absorbed in tension without cracking, even when strain is applied for part of the time at rates 2 to 3 times the normal shrinkage rate. The strength of such specimens is not reduced below the unirradiated value by the presence of creep strain. Temperature transients due to operational difficulties caused the development of radial cracks in some specimens, of which a few failed completely. Thus tensile failure appears to be preceded by the development of such fine cracks. (auth)

• Research Organization: United Kingdom Atomic Energy Authority, Culcheth (England). Reactor Group
• NSA Number: NSA-21-003557
• OSTI ID: 4463982
• Report Number(s): TRG-Report--1279; JNPC-MWP(GSG)/P--(66)69
• Country of Publication: United Kingdom
• Language: English

Related Subjects

BR-2
CRACKS
CREEP
DEFORMATION
EXPANSION
FAILURES
FAST NEUTRONS
GRAPHITE
N30250* --Metals
Ceramics
& Other Materials--Ceramics & Cermets--Radiation Effects
OPERATION
RESEARCH REACTORS
TEMPERATURE
TENSILE PROPERTIES
TRANSIENTS