Intergranular stress-corrosion cracking IGSCC

Many instances of intergranular stress corrosion cracking (IGSCC) of stainless steel and nickel-based alloys have occurred in the reactor water systems of BWRs. IGSCC, first observed in the recirculation piping systems (21) and later in reactor vessel internal components, has been observed primarily in the weld heat-affected zone of Type 304 stainless steel. 

As with all standardized tests (e g., the ASTM A 262 procedures previously discussed), correlations must be established between the EPR Pa values and service performance. For example, a criterion of Pa < 2 C/cm2 has been proposed for adequate resistance to intergranular corrosion leading to intergranular stress-corrosion cracking (IGSCC) of type 304 and 304L pipe and welds. Other limits would be set depending on the material, application, and environment (Ref 105, 106). 

Control of halogen elements in materials (e.g. pipe insulation) in contact with stainless steel components should be ensured by design in order to avoid intergranular stress corrosion cracking (IGSCC). 

FIGURE 3.13 Areas that are related in intergranular stress corrosion cracking (IGSCC). 

In 1994, cracks caused by intergranular stress corrosion cracking (IGSCC) were observed during visual inspection on some parts of the core internals in the oldest German BWR plant in operation, manufactured of niob-stabilized stainless steel. The intended replacement of the core shroud was not performed because of the economically motivated decision to decommission the plant. 

In the eighties, systematic failures were detected and investigated at outer and inner core-shroud bolts in German PWR plants. The damage can be described as pure intergranular stress corrosion cracking (IGSCC). 

Abstract This chapter reviews current research into stress corrosion cracking (SCC) in magnesium (Mg) alloys, particularly intergranular stress corrosion cracking (IGSCC) and transgranular stress corrosion cracking... 

The PWS has been susceptible to intergranular stress corrosion cracking (IGSCC) and irradiation-assisted stress corrosion cracking (lASCC). The effects are assessed below. 

A true ASME Section XI type inspection baseline does not exist for the SRS reactors due to the vintage of the plant and other limitations. Therefore, the data from each scheduled inspection will be analyzed to form an equivalent baseline. Examination methods and SRS categorization of weldments based on intergranular stress corrosion cracking (IGSCC) susceptibility are described in detail in Section III of the ISI plan. Inspection schedules, examination methods, frequency, and successive intervals for piping, heat exchangers, and reactor welds are described in the tables of the plan. (The-evaluation of reactor tank UT examinations, which are required for restart, is discussed below. 

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