ML14230A911

Enclosure - Example AMP - July 17, 2014, Summary of Meeting with Exelon Corporation to Discuss Request for Additional Information No. 4 to the Calvert Cliffs ISFSI License Renewal Application (Docket No. 72-08) TAC L24475

ML14230A911
Person / Time
Site:	Calvert Cliffs
Issue date:	08/18/2014
From:	Darrell Dunn NRC/NMSS/SFST
To:
Goshen J
Shared Package
ML14230A903	List: ML14230A908 ML14230A909 ML14230A910 ML14230A911 ML14230A913
References
TAC L24475
Download: ML14230A911 (16)

Text

Aging Management Program Example for Stress Corrosion Cracking Darrell S. Dunn Meeting to Discuss the Request for Additional Information Responses p Regarding g g the Calvert Cliffs Independent p Spent p

Fuel Storage Facility License Renewal July 17, 2014

Stress Corrosion Cracking Background Information

• 304 and 316 Stainless steels are susceptible to chloride stress corrosion cracking (SCC)

- Sensitization from welding increases susceptibility

- Crevice and pitting corrosion can be precursors to SCC

- SCC possible with low surface chloride concentrations

• Welded stainless steel canisters have sufficient through wall tensile residual stresses for SCC 2/3 of the requirements

• At Atmospheric h i SCC off welded ld d stainless steels has been observed for SCC are present in - Component failures in 16-33 years welded stainless steel - Estimated crack ggrowth rates of 0.11 to 0.91 mm/yr canisters 2

Regulatory Basis

• 10 CFR 72.42(a), 72.240(c):

TLAAs that demonstrate that ITS SSCs will continue to perform their intended function for the period of extended operation.

A description of the AMP for management of issues associated with aging that could adversely affect ITS SSCs.

• Guidance: NUREG-1927 AMP Elements:

1. Scope of the Program 6. Acceptance Criteria

2. Preventive Actions 7. Corrective Actions

3. Parameters Monitored/Inspected 8. Confirmation Process

4. Detection of Aging Effects 9. Administrative Controls

5. Monitoring and Trending 10. Operating Experience 3

AMP Element 1 Scope of the Program NUREG-1927: The scope of the program should include the specific structures and components subject to an AMR

• Welded stainless steel dry storage canisters

- Fabrication and closure welds

- Weld heat affected zones

- Locations where temporary supports or fixtures were attached by welding

- Crevice locations

- Surface areas where atmospheric deposits preferentially occurs

- Surface areas with a lower than average temperature 4

AMP Element 2 Preventative Actions NUREG-1927: Preventive actions should mitigate or prevent the applicable aging effects

• Aging Management Program (AMP) is for condition monitoring monitoring.

- Preventative actions are not presently incorporated into existing dry storage canister designs

• Future designs or amendments could include

- Surface modification to impart compressive residual stresses on welds and weld heat affected ff zones

- Materials with improved localized corrosion and SCC resistance 5

AMP Element 3 Parameters Monitored/Inspected NUREG-1927: Parameters monitored or inspected should be linked to the effects of aging on the intended functions of the particular structure and component

• Canister surfaces,, welds,, and weld heat affected zones for discontinuities and imperfections

• Size and location of localized corrosion (e.g., ( g pitting and crevice corrosion) and stress corrosion cracks

• Appearance and location of atmospheric deposits on the canister surfaces 6

AMP Element 4 Detection of Aging Effects (1/2)

NUREG-1927: Define method or technique, frequency, sample size, data collection, and timing to ensure timely detection of aging effects

• Qualified and demonstrated technique to detect evidence of localized corrosion and SCC:

- Remote visual inspection, e.g. EVT-1, VT-1, VT-3, or Eddy Current Testing (ET) may be appropriate

• PPending di d detection t ti fifindings, di sizing i i SCC would ld require i

volumetric methods 7

AMP Element 4 Detection of Aging Effects (2/2)

• Sample p size

- Minimum of one canister at each site

- Canisters with the greatest susceptibility

• Data Collection

- Documentation of the examination of the canister

- Location and appearance of deposits

• Frequency

- Every 5 years

• Timing of Inspections

- Within 25 years of initial loading 8

AMP Element 5 Monitoring and Trending NUREG-1927: Should provide for prediction of the extent of the effects of aging and timely corrective or mitigative actions

• Document canister condition particularly at welds and crevice locations using images and video that will allow comparison in subsequent examinations

• Changes to the size and number of any corrosion product accumulations

• Location and sizing of localized corrosion and stress corrosion cracking 9

AMP Element 6 Acceptance Criteria (1/2)

NUREG-1927: Acceptance criteria, against which the need for corrective action will be evaluated;; should ensure that SSC functions are maintained

• No indications of:

- Pitting or crevice corrosion

- Stress corrosion cracking

- Corrosion products near crevices

- Corrosion products on or adjacent to fabrication welds, closure welds welds, and welds for temporary supports or attachments 10

AMP Element 6 Acceptance Criteria (2/2)

• Locations with corrosion products require additional examination for localized corrosion and/or SCC

• Size of the area affected and the depth of penetration if localized corrosion and/or SCC is identified

• Canisters with localized corrosion and/or SCC must be evaluated for continued service in accordance with ASME B&PV Code Section XI IWB-3514.1 and IWB-3640 11

AMP Element 7 Corrective Actions NUREG-1927: Corrective actions, including root cause determination and prevention of recurrence, should be timely

• Supplemental inspections to determine the extent of condition at the site

• Subsequent inspections of canisters with indications

• Canisters that do not meet the prescribed evaluation criteria must be repaired p or removed from service 12

AMP Element 8 Confirmation Process NUREG-1927: Confirmation process should ensure that preventive q

actions are adequate & appropriate pp p corrective actions have been completed & are effective

• Licensee Quality Assurance Program consistent with 10 CFR 72 Subpart G G, or 10 CFR 50 Appendix B p

• Ensure that inspections, , evaluations,, and corrective actions are completed in accordance with the Site Specific or General Licensees Corrective Action Program (CAP)

- Extent of condition

- Evaluation for continued service

- Repair, replace, mitigation actions 13

AMP Element 9 Administrative Controls NUREG-1927: Administrative controls should provide a formal review and approval process

• Licensee Quality Assurance Program consistent with 10 CFR 72 Subpart G G, or 10 CFR 50 Appendix B

• Training requirements for inspectors

• Records retention requirements 14

AMP Element 10 Operational Experience NUREG-1927: Include past corrective actions; provide objective evidence to support a determination that the effects of aging will be adequately managed so that the SSC intended functions will be maintained during the period of extended operation

• No reported cases of localized corrosion or SCC in welded stainless steel canisters

• Atmospheric deposits on canister surfaces have been observed

• Several reported cases of chloride induced SCC from atmospheric deposits observed in operating reactors (NRC Information Notice 2012-20)

• Laboratoryy and field test data on conditions necessaryy for chloride induced SCC and SCC growth rates 15

Acronyms AMP: Aging management program TLAA: time limiting aging analysis AMR: Aging management review ITS: Important to safety ASME B&PV code: American Societyy SCC: Stress corrosion crackingg of Mechanical Engineers Boiler and Pressure Vessel code SSC: Structures systems and components CAP: Corrective action pprogram g

VT-1: Visual Testing-1 (ASME B&PV CFR: Code of Federal Regulations code Section XI, Article IWA-2200)

EVT-1:

EVT 1: Enhanced visual testing testing-1 1 VT-3:

VT 3: Visual Testing-3 Testing 3 (ASME B&PV (Boiling water reactor vessels and code Section XI, Article IWA-2200) internals project, BWRVIP-03) 16