Session: CS-21-01 Constraint Effects on C&S

Paper Number: 106269

106269 - Application of the J-Q Methodology to Consider the Geometrical Effect on Fracture for Large Steam-Generator Tubesheet 

In the frame of a Fracture Mechanics Assessement in the perforated part of the steam-generator tubesheet, a defect relying two holes is postulated, which represent a singular configuration compared to conventional FMA. Indeed the defect is relatively small in comparison to the plate thickness and the crack length is limited by the distance between two holes .

To take benefit of the geometry effect of this configuration, an application of the two parameters J-Q approach is performed on tubesheet component .

At first, the methodology was applied to define and valid the methology on an experimental data base which different constraint effect .This data base contains numerous fracture tests performed by both EDF and Framatome on various specimen geometries extracted from a 18MND5 low alloy ferritic steel plate, in the brittle-to-ductile transition regime. C (T) , SEN (T) , SEN (B) , and non - standard specimens .

Then this methodology is applied to predict the benefits of this approached for tubesheet configuration . Different configurations are tested : underclad defect, surface defect, mechanical loading, thermal shock, in the middle of the perforated zone or near the border of the perforated zone .

These applications show some significant constraint effect for underclad defect and some moderate effect for surface effect.

A methodology is proposed to correct the classical Engineering Fracture Mechanics Assessment to gain margins without considering any probability of failure or statical approach .

 

Presenting Author: Olivier Ancelet Framatome

Presenting Author Biography: Olivier is an senior expert in Framatome on fatigue and fracture.

Authors:

Olivier Ancelet Framatome
Stephane Marie Framatome
Stéphane Chapuliot EDF
Aurore Parrot EDF