ML14230A911
| ML14230A911 | |
| Person / Time | |
|---|---|
| Site: | Calvert Cliffs  |
| Issue date: | 08/18/2014 |
| From: | Darrell Dunn NRC/NMSS/SFST |
| To: | |
| Goshen J | |
| Shared Package | |
| ML14230A903 | List: |
| References | |
| TAC L24475 | |
| Download: ML14230A911 (16) | |
Text
Aging Management Program Aging Management Program Example for Stress Corrosion Cracking Darrell S. Dunn Darrell S. Dunn Meeting to Discuss the Request for Additional Information Responses Regarding the Calvert Cliffs Independent Spent p
g g
p p
Fuel Storage Facility License Renewal July 17, 2014
Stress Corrosion Cracking Background Information Background Information 304 and 316 Stainless steels are susceptible to chloride stress 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 2/3 of the requirements Welded stainless steel canisters have sufficient through wall tensile residual stresses for SCC At h
i SCC f
ld d 2/3 of the requirements for SCC are present in welded stainless steel Atmospheric SCC of welded stainless steels has been observed
- Component failures in 16-33 years
- Estimated crack growth rates of 0.11 canisters g
to 0.91 mm/yr 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 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 2.
Preventive Actions 3.
Parameters Monitored/Inspected 6.
Acceptance Criteria 7.
Corrective Actions 8.
Confirmation Process 4.
Detection of Aging Effects 5.
Monitoring and Trending 9.
Administrative Controls
- 10. Operating Experience 3
AMP Element 1 Scope of the Program 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 structures and components subject to an AMR
- Fabrication and closure welds
- Weld heat affected zones
- Locations where temporary supports or fixtures were 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
- Surface areas with a lower than average temperature 4
AMP Element 2 Preventative Actions Preventative Actions NUREG-1927: Preventive actions should mitigate or prevent the applicable aging effects
- Aging Management Program (AMP) is for condition monitoring applicable aging effects condition 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 ff stresses on welds and weld heat affected zones
- Materials with improved localized corrosion and SCC resistance resistance 5
AMP Element 3 Parameters Monitored/Inspected 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
- Canister surfaces, welds, and weld heat affected the effects of aging on the intended functions of the particular structure and component 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)
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:
data collection, and timing to ensure timely detection of aging effects of localized corrosion and SCC:
- Remote visual inspection, e.g. EVT-1, VT-1, VT-3, or Eddy Current Testing (ET) may be appropriate P
di d t ti fi di i i SCC ld i
- Pending detection findings, sizing SCC would require volumetric methods 7
AMP Element 4 Detection of Aging Effects (2/2)
Detection of Aging Effects (2/2)
- Sample size p
- 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
- Location and appearance of deposits
- Frequency
- Every 5 years Every 5 years
- Timing of Inspections
- Within 25 years of initial loading 8
AMP Element 5 Monitoring and Trending 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 of aging and timely corrective or mitigative actions 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)
Acceptance Criteria (1/2)
NUREG-1927: Acceptance criteria, against which the need for corrective action will be evaluated; should ensure that SSC functions
- No indications of:
are maintained
- Pitting or crevice corrosion
- Corrosion products near crevices
- Corrosion products on or adjacent to fabrication welds, closure welds and welds for temporary supports or closure welds, and welds for temporary supports or attachments 10
AMP Element 6 Acceptance Criteria (2/2)
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 identified
- Canisters with localized corrosion and/or SCC must be evaluated for continued service in 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 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 and prevention of recurrence, should be timely extent of condition at the site
- Subsequent inspections of canisters with indications
- Canisters that do not meet the prescribed evaluation criteria must be repaired or removed p
from service 12
AMP Element 8 Confirmation Process Confirmation Process NUREG-1927: Confirmation process should ensure that preventive actions are adequate & appropriate corrective actions have been
pp p
completed & are effective with 10 CFR 72 Subpart G, or 10 CFR 50 Appendix B
- Ensure that inspections, evaluations, and p
corrective actions are completed in accordance with the Site Specific or General Licensees Corrective Action Program (CAP)
Corrective Action Program (CAP)
- Extent of condition
- Evaluation for continued service
- Repair, replace, mitigation actions 13
AMP Element 9 Administrative Controls 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 or 10 CFR 50 and approval process with 10 CFR 72 Subpart G, or 10 CFR 50 Appendix B
- Training requirements for inspectors
- Training requirements for inspectors
- Records retention requirements 14
AMP Element 10 Operational Experience Operational Experience NUREG-1927: Include past corrective actions; provide objective evidence to support a determination that the effects of aging will be
- No reported cases of localized corrosion or SCC in 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 atmospheric deposits observed in operating reactors (NRC Information Notice 2012-20)
- Laboratory and field test data on conditions necessary for y
y chloride induced SCC and SCC growth rates 15
Acronyms Acronyms AMP: Aging management program TLAA: time limiting aging analysis AMR: Aging management review ASME B&PV code: American Society ITS: Important to safety SCC: Stress corrosion cracking y
of Mechanical Engineers Boiler and Pressure Vessel code CAP: Corrective action program g
SSC: Structures systems and components p
g CFR: Code of Federal Regulations EVT 1: Enhanced visual testing 1 VT-1: Visual Testing-1 (ASME B&PV code Section XI, Article IWA-2200)
VT 3: Visual Testing 3 (ASME B&PV EVT-1: Enhanced visual testing-1 (Boiling water reactor vessels and internals project, BWRVIP-03)
VT-3: Visual Testing-3 (ASME B&PV code Section XI, Article IWA-2200) 16