Quantitative Prediction of Environmentally Assisted Cracking in Boiling Water Reactors

Abstract

Genera] Eiectric Corporate R and D Center, Schenectady, New York12301, USA (Retired) Enyironmental]y-as.sisted cracking has presented a significant structural integrity problem in various industries including marine, petrochemica], aerospace and power generation, This may be agrib,uted to various factors, including inadequate data bases for engineering-based design criteria, and the complex interactions between the relevant material, stress and enviro{}mental conditions, which make it difficult to develop effective life prediction strategLes.This situation is offset by the increase in quantitative understanding of the mechanisms of cracking over the last 20 years. This paper reviews the role that such developments have had in mitigating the problem of stress corrosion and corrosion fatigue of ductile structural alloys in boi]ing water reactors (BWRs). These reactors have experienced cracking problems in austenitic and ferritic alloys in, for instance, piping, pressure vessels and in irradiated core internals. Emphasis in this paper wM be placed on describing, (a) the development and qua lification of a mechanistically-based prediction methodology fbr the releyant degradation mode and,(b) the use of such a qualified methodology for proactive, cost-effective, life-managementdecisions.

Early Detection of the Material Degradation Based on the Integrated Analysis of Diverse Measurement Techniques

“…For example, the Environmentally Assisted Cracking (EAC) of components of light water reactor should be examined further. Despite the extensive efforts in the material study [1], the occurrences of unexpected leakage and cracks have not been eliminated completely [2]. The condition based monitoring strategy is now being introduced in the nuclear plant, in which the states of the structural components are monitored extensively to prevent the occurrence of failure in advance.…”