Abstract
The Zr-2.5% Nb alloy pressure tube provides the primary containment for coolant in the CANDU reactor. Because these tubes contain the individual fuel strings and pass neutron flux of up to 4.0 x 10{sup 17} neutrons per square meter per second (E > 1 MeV). Any demonstration of the integrity of these tubes relies on a leak-before-break (LBB) assessment, which, in turn, depends on the fracture properties of the tube. These properties become degraded with service due to both the gradual pickup of hydrogen isotopes and the reduction of fracture toughness due to irradiation. This paper gives an overview of the relevant fracture properties used in the LBB scenario and the effect of service conditions on their degradation. The particular properties discussed are the susceptability to subcritical crack growth by delayed hydride cracking, and the reduction in fracture toughness which reduces the critical crack length. Methods of protecting the tubes against fracture and improving their properties are discussed.
Simpson, L A;
[1]
Coleman, C E
[2]
- Atomic Energy of Canada Ltd., Pinawa, MB (Canada). Whiteshell Nuclear Research Establishment
- Atomic Energy of Canada Ltd., Chalk River, ON (Canada). Chalk River Nuclear Labs.
Citation Formats
Simpson, L A, and Coleman, C E.
Mitigation of degradation mechanisms affecting CANDU pressure tubes.
Canada: N. p.,
1990.
Web.
Simpson, L A, & Coleman, C E.
Mitigation of degradation mechanisms affecting CANDU pressure tubes.
Canada.
Simpson, L A, and Coleman, C E.
1990.
"Mitigation of degradation mechanisms affecting CANDU pressure tubes."
Canada.
@misc{etde_10140409,
title = {Mitigation of degradation mechanisms affecting CANDU pressure tubes}
author = {Simpson, L A, and Coleman, C E}
abstractNote = {The Zr-2.5% Nb alloy pressure tube provides the primary containment for coolant in the CANDU reactor. Because these tubes contain the individual fuel strings and pass neutron flux of up to 4.0 x 10{sup 17} neutrons per square meter per second (E > 1 MeV). Any demonstration of the integrity of these tubes relies on a leak-before-break (LBB) assessment, which, in turn, depends on the fracture properties of the tube. These properties become degraded with service due to both the gradual pickup of hydrogen isotopes and the reduction of fracture toughness due to irradiation. This paper gives an overview of the relevant fracture properties used in the LBB scenario and the effect of service conditions on their degradation. The particular properties discussed are the susceptability to subcritical crack growth by delayed hydride cracking, and the reduction in fracture toughness which reduces the critical crack length. Methods of protecting the tubes against fracture and improving their properties are discussed.}
place = {Canada}
year = {1990}
month = {Dec}
}
title = {Mitigation of degradation mechanisms affecting CANDU pressure tubes}
author = {Simpson, L A, and Coleman, C E}
abstractNote = {The Zr-2.5% Nb alloy pressure tube provides the primary containment for coolant in the CANDU reactor. Because these tubes contain the individual fuel strings and pass neutron flux of up to 4.0 x 10{sup 17} neutrons per square meter per second (E > 1 MeV). Any demonstration of the integrity of these tubes relies on a leak-before-break (LBB) assessment, which, in turn, depends on the fracture properties of the tube. These properties become degraded with service due to both the gradual pickup of hydrogen isotopes and the reduction of fracture toughness due to irradiation. This paper gives an overview of the relevant fracture properties used in the LBB scenario and the effect of service conditions on their degradation. The particular properties discussed are the susceptability to subcritical crack growth by delayed hydride cracking, and the reduction in fracture toughness which reduces the critical crack length. Methods of protecting the tubes against fracture and improving their properties are discussed.}
place = {Canada}
year = {1990}
month = {Dec}
}