Modeling In-Reactor Deformation of Zr-2.5Nb Pressure Tubes in CANDU Power Reactors

2009 ◽  
pp. 518-518-20 ◽  
Author(s):  
N Christodoulou ◽  
AR Causey ◽  
RA Holt ◽  
CN Tomé ◽  
N Badie ◽  
...  
Keyword(s):  
Pressure Tubes

A Statistical-Based Fatigue Crack Initiation Model for Axial Flaws in Zr-Nb Pressure Tubes

2014 ◽  
Author(s):  
Cheng Liu ◽  
Douglas Scarth ◽  
Alain Douchant
Keyword(s):  
Fatigue Crack ◽  
Crack Initiation ◽  
Rise Time ◽  
Structural Integrity ◽  
Fatigue Crack Initiation ◽  
Mechanical Damage ◽  
Fuel Bundle ◽  
Test Parameters ◽  
Pressure Tubes ◽  
Criteria For Evaluation

Flaws found during in-service inspection of CANDU Zr-2.5Nb pressure tubes include fuel bundle scratches, debris fretting flaws, fuel bundle bearing pad fretting flaws, mechanical damage flaws and crevice corrosion marks. The CSA Standard N285.8 contains procedures and acceptance criteria for evaluation of the structural integrity of CANDU Zr-2.5Nb pressure tubes containing flaws. One of the requirements is to evaluate the flaws for fatigue crack initiation. There was a need to develop a statistical-based model of fatigue crack initiation at flaws for use in deterministic and probabilistic assessments of Zr-2.5Nb pressure tubes. A number of fatigue crack initiation experiments have been performed on notched specimens from irradiated and unirradiated Zr-2.5Nb pressure tube material with a range of hydrogen equivalent concentrations. These experiments were performed in an air environment and included temperature and load rise time as test parameters. The test data has been used to develop a statistical-based model of fatigue crack initiation at flaws that covers the effects of flaw root radius, load rise time and irradiation. This paper describes the development of the statistical-based model.

Development and Characterization of Microstructure and Mechanical Properties of Heat-Treated Zr–2.5Nb Alloy for AHWR Pressure Tubes

2013 ◽  
Vol 2 (1) ◽  
pp. 20120033
Author(s):  
R. N. Singh ◽  
A. K. Bind ◽  
J. B. Singh ◽  
J. K. Chakravartty ◽  
V. Thomas Paul ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Microstructure And Mechanical Properties ◽  
Heat Treated ◽  
Pressure Tubes

Experiences in Examining and Dispositioning Flaws in Zr-2.5Nb Pressure Retaining CANDU Reactor Components

2002 ◽  
Author(s):  
Andrew Celovsky ◽  
John Slade
Keyword(s):  
Service Life ◽  
Reactor Core ◽  
Pressure Tube ◽  
Candu Reactors ◽  
Periodic Inspection ◽  
Pressure Tubes ◽  
Surveillance Programs ◽  
Non Destructive ◽  
Limited Service ◽  
Non Destructive Techniques

CANDU reactors use Zr-2.5 Nb alloy pressure tubes, as the primary pressure boundary within the reactor core. These components are subject to periodic inspection and material surveillance programs. Occasionally, the inspection program uncovers a flaw, whereupon the flaw is assessed as to whether it compromises the integrity of the pressure-retaining component. In 1998, such a flaw was observed in one pressure tube of a reactor. Non-destructive techniques and analysis were used to form a basis to disposition the flaw, and the component was fit for a limited service life. This component was eventually removed from service, whereupon the destructive examinations were used to validate the disposition assumptions used. Such a process of validation provides credibility to the disposition process. This paper reviews the original flaw and its subsequent destructive evaluation.

Measurement and analysis of the elongation of Zircaloy-2 pressure tubes in pickering generating station units 1 and 2

1980 ◽  
Vol 58 (3) ◽  
pp. 367-381 ◽  
Author(s):  
A.R. Causey ◽  
S.R. MacEwen ◽  
H.C. Jamieson ◽  
A.B. Mitchell
Keyword(s):  
Measurement And Analysis ◽  
Pressure Tubes

scholarly journals A simplified analysis of the Chernobyl accident

2021 ◽  
Vol 7 ◽  
pp. 1
Author(s):  
Bertrand Mercier ◽  
Di Yang ◽  
Ziyue Zhuang ◽  
Jiajie Liang
Keyword(s):  
Numerical Models ◽  
List Type ◽  
Flash Evaporation ◽  
The Core ◽  
Large Size ◽  
Reaction Coefficient ◽  
Pressure Tubes ◽  
Void Effect ◽  
Reactivity Coefficient ◽  
Reactivity Increase

We show with simplified numerical models, that for the kind of RBMK operated in Chernobyl: The core was unstable due to its large size and to its weak power counter-reaction coefficient, so that the power of the reactor was not easy to control even with an automatic system. Xenon oscillations could easily be activated. When there was xenon poisoning in the upper half of the core, the safety rods were designed in such a way that, at least initially, they were increasing (and not decreasing) the core reactivity. This reactivity increase has been sufficient to lead to a very high pressure increase in a significant amount of liquid water in the fuel channels thus inducing a strong propagating shock wave leading to a failure of half the pressure tubes at their junction with the drum separators. The depressurization phase (flash evaporation) following this failure has produced, after one second, a significant decrease of the water density in half the pressure tubes and then a strong reactivity accident due to the positive void effect reactivity coefficient. We evaluate the fission energy released by the accident

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