ML22059A082

March 3 2022 NRC Public Meeting with Steam Generator Task Force - NRC Presentation

ML22059A082
Person / Time
Issue date:	03/03/2022
From:	NRC/NRR/DNRL/NCSG
To:
Terry L
References
TSTF-577
Download: ML22059A082 (15)

Text

Draft NRC Response Clarification of Inspection Requirements in Technical Specifications Task Force 577 (TSTF-577)

NRC Meeting with Industry Steam Generator Task Force (SGTF)

March 3, 2022

Outline

• Background

- TSTF-577 - Revised Frequencies for Steam Generator (SG) Tube Inspections

• SGTF Request for Clarification on TSTF-577 Inspection Requirements

• Draft NRC Response to SGTF Clarification Request

• Standardizing Titles of SG Tube Inspection Reports 2

Background

• TSTF-577, which made changes to the Standard Technical Specifications (STS) for pressurized water reactors, was issued on April 14, 2021

- Longer inspection intervals for thermally-treated Alloy 600 (48 Effective Full Power Months (EFPM) to 54 EFPM) and thermally-treated Alloy 690 (72 EFPM to 96 EFPM) tubing

- For thermally-treated Alloy 600 only:

• Conditional 72 EFPM for plants that have no cracking history and that perform a 100 percent enhanced probe inspection

• Conditional relaxation to inspect at the second refueling outage after crack indications are detected if 100 percent enhanced probe inspections are performed 3

Background Contd

- Added definition of 100 percent enhanced probe inspection

- Updated requirements for SG tube inspection reports

- Editorial changes

- Incorporation of changes in NRC-approved TSTF-510, Revision 2

• TSTF-577 changes have been incorporated into Revision 5 of the STS:

- NUREG-1430 (Babcock and Wilcox)

- NUREG-1431 (Westinghouse)

- NUREG-1432 (Combustion Engineering) 4

SGTF Request for Clarification

• December 9, 2021 - SGTF submitted a letter requesting clarification on TSTF-577 inspection requirements

- STS Section 5.5.9.3 - Clarify the scope of the next inspection after crack indications are found

- STS Section 5.5.9.2 - For thermally-treated Alloy 600 units with 72 EFPM intervals, can inspections be staggered once the initial 100% inspection is performed 5

Draft NRC Response to SGTF Clarification Request

• STS 5.5.9.3 - Minimum inspection requirements for the next refueling outage is for the degradation mechanism that caused the crack indication, in the affected and potentially affected SGs, based on the degradation assessment

• STS Section 5.5.9.2 - No prohibitions against allowing SG tube inspections to be switched to a staggered inspection approach after the initial 100 percent enhanced probe method inspection scope is completed

- Staggered inspection approach may involve:

• 100 percent inspection of alternating SGs (e.g., SGs 1 and 3 in one outage, followed by SGs 2 and 4 in a subsequent outage)

• Partial inspection of all SGs (e.g., 50 percent of SGs A, B, and C in one outage, followed by the remaining 50 percent of SGs A, B, and C in a subsequent outage)

- Developed inspection scenarios of how a plant operating within a 72 EFPM inspection interval would be affected by the detection of cracking for the first time during a staggered inspection 6

Staggered Inspections (18-month) 7

Inspection Scenario 1 Initial Crack Detection Next Inspection and Beyond Initial 100% enhanced probe After two cycles, a 100% All SGs are now limited to a 54 EFPM maximum inspection was performed on enhanced probe inspection is inspection period [basis: TS 5.5.9.d.2].

all four SGs and no cracking is performed in SGs 1/3.

detected. The SGs enter a 72 Cracking detected in SG 1. SGs 1/3 - since a 100% enhanced probe EFPM inspection period. SG 3 had no cracking inspection was performed and cracking was Thereafter, staggered detected but is potentially detected, inspection for the degradation inspections by SG (e.g., SGs affected by the degradation mechanism is required at the second 1/3 and SGs 2/4 are offset by mechanism. subsequent RFO [basis: TS 5.5.9.d.3].

two refueling outages (RFOs) on an 18-month fuel cycle). SGs 2/4 may or may not have SGs 2/4 - inspection is required at the next RFO received a partial inspection to meet (i) the 54 EFPM maximum inspection from initial scope expansion period [basis: TS 5.5.9.d.2], and (ii) since the but are potentially affected SGs did not receive a 100% enhanced probe by the degradation inspection after cracking was detected in SG 1 mechanism. [basis: TS 5.5.9.d.3].

All SGs are now limited to a 54 EFPM maximum inspection period.

8

Inspection Scenario 1a Initial Crack Detection Next Inspection and Beyond Initial 100% enhanced After two cycles, enhanced All SGs are now limited to a 54 EFPM maximum inspection probe inspection to enter probe inspection is period [basis: TS 5.5.9.d.2].

72 EFPM. Thereafter, performed on all tubes staggered inspections by within the subpopulation in If less than 100% of tubes were inspected with the SG sub-population (e.g., all SGs (e.g., 50% of each SG enhanced probe in all affected and potentially affected 50% of each SG per outage per inspection). Cracking offset by two RFOs on an detected in one SG. SGs, then inspection for the degradation mechanism is 18-month fuel cycle). required at the next refueling outage [basis: TS 5.5.9.d.3].

All SGs are now limited to a In addition, any sub-population of tubes not inspected by 54 EFPM maximum an enhanced probe during the RFO when cracking was inspection period. detected would need to be inspected at the next RFO to satisfy the 54 EFPM inspection period [basis: TS 5.5.9.d.2].

If 100% of all tubes (scope expansion) in all SGs were inspected with the enhanced probe, inspection for the degradation mechanism for affected and potentially affected SGs is required at the second subsequent refueling outage [basis: TS 5.5.9.d.3]. Those tubes not inspected at the second subsequent refueling outage would be inspected at the third subsequent refueling outage to satisfy the 54 EFPM inspection period [basis: TS 5.5.9.d.2].

9

Staggered Inspections (24-month) 10

Inspection Scenario 2 Initial Crack Detection Next Inspection and Beyond Initial 100% enhanced A 100% enhanced probe All SGs are now limited to a 54 EFPM maximum probe inspection to inspection performed in inspection period [basis: TS 5.5.9.d.2].

enter 72 EFPM. SGs A, B, and C after 72 Subsequent 100% EFPM. Cracking SGs A, B, and C - since a 100% enhanced probe enhanced probe detected in SG A. SGs B inspection was performed, inspection for the inspections every 3rd and C had no cracking degradation mechanism is required at the second RFO (24-month fuel detected. subsequent RFO (after 48 EFPM) [basis: TS cycle). 5.5.9.d.3].

All SGs are now limited to a 54 EFPM maximum In addition, the second subsequent RFO will likely inspection period. be used to meet the 54 EFPM maximum inspection period requirement [basis: TS 5.5.9.d.2].

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Inspection Scenario 2a Initial Crack Detection Next Inspection and Beyond Initial 100% enhanced A 100% enhanced probe All SGs are now limited to a 54 EFPM maximum probe inspection to inspection performed in inspection period [basis: TS 5.5.9.d.2].

enter 72 EFPM SGs A and B after 48 inspection period. EFPM. Cracking detected Therefore, SG C will likely be inspected at the time Staggered inspections by in SG A. SG B had no cracking was detected in SG A to meet the 54 EFPM SG (e.g., SGs A/B and SG cracking detected. maximum inspection period requirement [basis: TS C are offset starting two 5.5.9.d.2].

refueling outages (RFOs) All SGs are now limited to on a 24-month fuel a 54 EFPM maximum Assuming 100% of all tubes in all SGs receive an cycle). inspection period. enhanced probe inspection, inspection for the degradation mechanism is required at the second subsequent RFO [basis: TS 5.5.9.d.3].

Assuming less than 100% of all tubes in all SGs receive an enhanced probe inspection, inspection for the degradation mechanism is required at the next subsequent RFO [basis: TS 5.5.9.d.3].

In addition, the second subsequent RFO will likely be used to meet the 54 EFPM maximum inspection period requirement [basis: TS 5.5.9.d.2].

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Standardizing Titles of SG Tube Inspection Reports

• Standardized titles improve:

- Distribution to appropriate NRC staff

- ADAMS search

• NRC requests industry use title in STS - Steam Generator Tube Inspection Report

• STS - Westinghouse Plants: Specifications (NUREG-1431, Revision 5, Volume 1) 13

References

• TSTF Response to NRC Questions on TSTF-577, Revision 0, Revised Frequencies for Steam Generator Tube Inspections, and Submittal of Revision 1, dated March 1, 2021 (ML21060B434)

• TSTF-577, Revision 1, Final Safety Evaluation Package (ML21099A086)

• SGTF Letter, Clarification of Inspection Requirements in Technical Specifications Task Force (TSTF) 577, dated December 9, 2021 (ML22006A030)

• NUREG-1430, Revision 5, Standard Technical Specifications - Babcock and Wilcox Plants, dated September 2021 (ML21272A363 (Volume 1) and ML21272A370 (Volume 2))

• NUREG-1431, Revision 5, Standard Technical Specifications - Westinghouse Plants, dated September 2021 (ML21259A155 (Volume 1) and ML21259A159 (Volume 2))

• NUREG-1432, Revision 5, Standard Technical Specifications - Combustion Engineering Plants, dated September 2021 (ML21258A421 (Volume 1) and ML21258A424 (Volume 2))

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Questions 15