DCL-22-011, License Amendment Request 22-02 Application to Revise Technical Specifications to Adopt TSTF 577, Revised Frequencies for Steam Generator Tube Inspections

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License Amendment Request 22-02 Application to Revise Technical Specifications to Adopt TSTF 577, Revised Frequencies for Steam Generator Tube Inspections
ML22069B122
Person / Time
Site: Diablo Canyon  Pacific Gas & Electric icon.png
Issue date: 03/10/2022
From: Peck A
Pacific Gas & Electric Co
To:
Document Control Desk, Office of Nuclear Reactor Regulation
References
DCL-22-011
Download: ML22069B122 (24)
v • d • e


Text

m PacHic Gas and Electric Company*

Adam S. Peck Site Vice President Diablo Canyon Power Plant Mail code 104/5/507 P.O. Box 56 Avila Beach, CA 93424 805.545.6675 Internal: 691.6675 PG&E Letter DCL-22-011 10 CFR 50.90 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, D.C. 20555-0001 Diablo Canyon Units 1 and 2 Docket No. 50-275, OL-DPR-80 Docket No. 50-323, OL-DPR-82 License Amendment Request 22-02 Application to Revise Technical Specifications to Adopt TSTF 577, Revised Frequencies for Steam Generator Tube Inspections

Dear Commissioners and Staff:

Pursuant to 10 CFR 50.90, Pacific Gas and Electric Company (PG&E) is submitting a request for an amendment to the Technical Specifications (TS) for the Diablo Canyon Power Plant (DCPP), Units 1 and 2.

PG&E requests adoption of TSTF 577, Revision 1, Revised Frequencies for Steam Generator Tube Inspections, which is an approved change to the Standard Technical Specifications, into the DCPP, Units 1 and 2, TS. The TS related to steam generator (SG) tube inspections and reporting are revised based on operating history.

The enclosure provides a description and assessment of the proposed changes.

Attachment 1 provides the existing TS pages marked to show the proposed changes. Attachment 2 provides revised (clean) TS pages. Attachment 3 provides the existing TS Bases pages marked to show revised text associated with the proposed TS changes and is provided for information only.

PG&E requests that the amendment be reviewed under the Consolidated Line Item Improvement Process. The existing TS require SG tube inspections every three refueling outages. The most recent 100 percent SG tube inspections were performed in DCPP Unit 2 Twenty-First Refueling Outage and DCPP 1 Unit Twenty-Second Refueling Outage. Therefore, the amendment is requested to be approved by October 3, 2022, to support removal of SG tube inspection scope from the DCPP Unit 2 Twenty-Fourth Refueling Outage in April 2024, which is the last refueling outage before expiration of the Unit 2 operating license in 2025. For DCPP Unit 1, the TSTF-577, Revision 1 changes are not planned to be utilized because the Unit 1 A member of the STARS Alliance Callaway

  • Diablo Canyon
  • Palo Verde
  • Wolf Creek

Document Control Desk PG&E Letter DCL-22-011 Page 2 operating license will expire in November 2024, before exceedance of the existing TS three refueling outage SG inspection frequency. Once approved, the amendment shall be implemented within 90 days.

PG&E makes no new or revised regulatory commitments (as defined by NEI 99-04) in this letter.

In accordance with 10 CFR 50.91, a copy of this application, with attachments, is being provided to the California Department of Public Health.

If you have any questions or require additional information, please contact Mr. James Morris at 805-545-4609.

I state under penalty of perjury that the foregoing is true and correct.

March 10, 2022 Executed on DATE: ____________

Sincerely, Adam Peck Site Vice President kjse/51066426 Enclosure cc: Diablo Distribution cc/enc: Neil H. Day, Acting NRC Senior Resident Inspector Samson S. Lee, NRR Senior Project Manager Scott A. Morris, NRC Region IV Administrator Gonzalo L. Perez, Branch Chief, California Department of Public Health A member of the STARS Alliance Callaway

  • Diablo Canyon
  • Palo Verde
  • Wolf Creek

Enclosure PG&E Letter DCL-22-011 Description and Assessment License Amendment Request 22-02 Application to Revise Technical Specifications to Adopt TSTF 577, Revised Frequencies for Steam Generator Tube Inspections

1. DESCRIPTION
2. ASSESSMENT 2.1 Applicability of Safety Evaluation 2.2 Variations
3. REGULATORY ANALYSIS 3.1 No Significant Hazards Consideration Analysis 3.2 Conclusions
4. ENVIRONMENTAL CONSIDERATION ATTACHMENTS:
1. Proposed Technical Specification Changes (Mark-Up)
2. Revised Technical Specification Pages
3. Proposed Technical Specification Bases Changes (Mark-Up) - For Information Only 1

Enclosure PG&E Letter DCL-22-011 DESCRIPTION AND ASSESSMENT

1. DESCRIPTION Pacific Gas and Electric Company (PG&E) requests adoption of TSTF-577, Revision 1, Revised Frequencies for Steam Generator Tube Inspections, which is an approved change to the Standard Technical Specifications (STS), into the Diablo Canyon Power Plant (DCPP), Units 1 and 2, Technical Specifications (TS). The TS related to steam generator (SG) tube inspections and reporting are revised based on operating history.
2. ASSESSMENT 2.1 Applicability of Safety Evaluation PG&E has reviewed the safety evaluation for TSTF-577 Revision 1 provided to the Technical Specifications Task Force in NRC letter dated April 14, 2021. This review included a review of the NRC staffs evaluation, as well as the information provided in TSTF-577 Revision 1. As described herein, PG&E has concluded that the justifications presented in TSTF-577 and the safety evaluation prepared by the NRC staff are applicable to DCPP, Units 1 and 2, and justify this amendment for the incorporation of the changes to the DCPP TS.

The current SG TS requirements are based on TSTF-449, Steam Generator Tube Integrity. The Unit 1 and Unit 2 SG tubes are made from Thermally Treated Alloy 690 (Alloy 690TT).

The TSTF-577 initial inspection period described in the SG Program, paragraph d.2, began in the DCPP Unit 2 Twenty-First Refueling Outage (October 2019) and in DCPP Unit 1 Twenty-Second Refueling Outage (1R22) (October 2020), in which 100 percent SG tube inspections were performed. PG&E will submit a DCPP Unit 2 SG Tube Inspection Report meeting the revised TS 5.6.10 requirements within 30 days after implementation of the license amendment. For DCPP Unit 1, the 180-day SG Tube Inspection Report submitted after 1R22 (PG&E letter DCL-21-036, One Hundred Eighty Day Steam Generator Report for Diablo Canyon Power Plant Unit 1 Twenty-Second Refueling Outage, dated April 22, 2021 [ADAMS Accession No. ML21112A158]) voluntarily provided the additional information required by revised TS 5.6.10, so additional DCPP Unit 1 reporting is not required.

2.2 Variations PG&E is proposing the following variations from the TS changes described in TSTF-577, Revision 1 or the applicable parts of the NRC staffs safety evaluation:

2

Enclosure PG&E Letter DCL-22-011

  • TS 5.5.9, paragraphs a, b, c, and d, are reformatted to remove a paragraph break between the first sentence and the remainder of the paragraph in order to be consistent with TSTF-577 Revision 1 and the STS.

These changes are administrative and do not affect the applicability of TSTF-577 to the DCPP TS.

3. REGULATORY ANALYSIS 3.1 No Significant Hazards Consideration Analysis Pacific Gas and Electric Company (PG&E) requests adoption of TSTF-577, Revision 1, Revised Frequencies for Steam Generator Tube Inspections, which is an approved change to the Standard Technical Specifications (STS), into the Diablo Canyon Power Plant (DCPP), Units 1 and 2, Technical Specifications (TS). The TS related to steam generator (SG) tube inspections and reporting are revised based on operating history.

PG&E has evaluated if a significant hazards consideration is involved with the proposed amendment(s) by focusing on the three standards set forth in 10 CFR 50.92, Issuance of amendment, as discussed below:

1. Does the proposed amendment involve a significant increase in the probability or consequences of an accident previously evaluated?

Response: No.

The proposed change revises the inspection frequencies for SG tube inspections and associated reporting requirements. The SG inspections are conducted as part of the SG Program to ensure and demonstrate that performance criteria for tube structural integrity and accident leakage integrity are met. These performance criteria are consistent with the plant design and licensing basis. With the proposed changes to the inspection 3

Enclosure PG&E Letter DCL-22-011 frequencies, the SG Program must still demonstrate that the performance criteria are met. As a result, the probability of any accident previously evaluated is not significantly increased and the consequences of any accident previously evaluated are not significantly increased.

Therefore, the proposed change does not involve a significant increase in the probability or consequences of an accident previously evaluated.

2. Does the proposed amendment create the possibility of a new or different kind of accident from any accident previously evaluated?

Response: No.

The proposed change revises the inspection frequencies for SG tube inspections and associated reporting requirements. The proposed change does not alter the design function or operation of the SGs or the ability of an SG to perform the design function. The SG tubes continue to be required to meet the SG Program performance criteria. The proposed change does not create the possibility of a new or different kind of accident due to credible new failure mechanisms, malfunctions, or accident initiators that are not considered in the design and licensing bases.

Therefore, the proposed change does not create the possibility of a new or different kind of accident from any accident previously evaluated.

3. Does the proposed amendment involve a significant reduction in a margin of safety?

Response: No.

The proposed change revises the inspection frequencies for SG tube inspections and associated reporting requirements. The proposed change does not change any of the controlling values of parameters used to avoid exceeding regulatory or licensing limits. The proposed change does not affect a design basis or safety limit, or any controlling value for a parameter established in the Updated Final Safety Analysis Report or the license.

Therefore, the proposed change does not involve a significant reduction in a margin of safety.

4

Enclosure PG&E Letter DCL-22-011 Based on the above evaluation, PG&E concludes that the proposed change does not involve a significant hazards consideration under the standards set forth in 10 CFR 50.92(c), and accordingly, a finding of no significant hazards consideration is justified.

3.2 Conclusion In conclusion, based on the considerations discussed above, (1) there is reasonable assurance that the health and safety of the public will not be endangered by operation in the proposed manner, (2) such activities will be conducted in compliance with the Commissions regulations, and (3) the issuance of the amendment will not be inimical to the common defense and security or to the health and safety of the public.

5. ENVIRONMENTAL CONSIDERATION A review has determined that the proposed amendment would change a requirement with respect to installation or use of a facility component located within the restricted area, as defined in 10 CFR 20, or would change an inspection or surveillance requirement. However, the proposed amendment does not involve (i) a significant hazards consideration, (ii) a significant change in the types or a significant increase in the amounts of any effluents that may be released offsite, or (iii) a significant increase in individual or cumulative occupational radiation exposure. Accordingly, the proposed amendment meets the eligibility criterion for categorical exclusion set forth in 10 CFR 51.22(c)(9).

Therefore, pursuant to 10 CFR 51.22(b), no environmental impact statement or environmental assessment need be prepared in connection with the proposed amendment.

5

Enclosure Attachment 1 PG&E Letter DCL-22-011 Proposed Technical Specification Changes (Mark-Up)

SG Tube Integrity 3.4.17 3.4 REACTOR COOLANT SYSTEM (RCS) 3.4.17 Steam Generator (SG) Tube Integrity LCO 3.4.17 SG tube integrity shall be maintained.

AND All SG tubes satisfying the tube plugging repair criteria shall be plugged in accordance with the Steam Generator Program.

APPLICABILITY: MODES 1, 2, 3, and 4.

ACTIONS

NOTE-------------------------------------------------------------

Separate Condition entry is allowed for each SG tube.

CONDITION REQUIRED ACTION COMPLETION TIME A. One or more SG tubes A.1 Verify tube integrity of the 7 days satisfying the tube plugging affected tube(s) is repair criteria and not maintained until the next plugged in accordance with refueling outage or SG the Steam Generator tube inspection.

Program.

AND A.2 Plug the affected tube(s) in Prior to entering accordance with the Steam MODE 4 following the Generator Program. next refueling outage or SG tube inspection B. Required Action and B.1 Be in MODE 3. 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> associated Completion Time of Condition A not AND met. B.2 Be in MODE 5. 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br /> OR SG tube integrity not maintained.

DIABLO CANYON - UNITS 1 & 2 3.4-37 Unit 1 - Amendment No. 194, Unit 2 - Amendment No. 195,

SG Tube Integrity 3.4.17 SURVEILLANCE REQUIREMENTS SURVEILLANCE FREQUENCY SR 3.4.17.1 Verify SG tube integrity in accordance with the Steam In accordance with Generator Program. the Steam Generator Program SR 3.4.17.2 Verify that each inspected SG tube that satisfies the Prior to entering tube plugging repair criteria is plugged in accordance MODE 4 following with the Steam Generator Program. a SG tube inspection DIABLO CANYON - UNITS 1 & 2 3.4-38 Unit 1 - Amendment No. 194, Unit 2 - Amendment No. 195,

Programs and Manuals 5.5 5.5 Programs and Manuals (continued) 5.5.9 Steam Generator (SG) Tube Inspection Program An SG Steam Generator Program shall be established and implemented to ensure that SG tube integrity is maintained. In addition, the SG Steam Generator Program shall include the following provisions:

a. Provisions for condition monitoring assessments.

Condition monitoring assessment means an evaluation of the as found condition of the tubing with respect to the performance criteria for structural integrity and accident induced leakage. The as found condition refers to the condition of the tubing during an SG inspection outage, as determined from the inservice inspection results or by other means, prior to the plugging of tubes.

Condition monitoring assessments shall be conducted during each outage during which the SG tubes are inspected or plugged to confirm that the performance criteria are being met.

b. Performance criteria for SG tube integrity.

SG tube integrity shall be maintained by meeting the performance criteria for tube structural integrity, accident induced leakage, and operational LEAKAGE.

1. Structural integrity performance criterion: All in-service SG steam generator tubes shall retain structural integrity over the full range of normal operating conditions (including startup, operation in the power range, hot standby, and cool down), and all anticipated transients included in the design specification), and design basis accidents. This includes retaining a safety factor of 3.0 against burst under normal steady state full power operation primary-to-secondary pressure differential and a safety factor of 1.4 against burst applied to the design basis accident primary-to-secondary pressure differentials. Apart from the above requirements, additional loading conditions associated with the design basis accidents, or combination of accidents in accordance with the design and licensing basis, shall also be evaluated to determine if the associated loads contribute significantly to burst or collapse. In the assessment of tube integrity, those loads that do significantly affect burst or collapse shall be determined and assessed in combination with the loads due to pressure with a safety factor of 1.2 on the combined primary loads and 1.0 on axial secondary loads.
2. Accident induced leakage performance criterion: The primary to secondary accident induced leakage rate for any design basis accident, other than a SG tube rupture, shall not exceed the leakage rate assumed in the accident analysis in terms of total leakage rate for all SGs and leakage rate for an individual SG. Except during a SG tube rupture, leakage is also not to exceed 1 gallon per minute per SG.

(continued)

DIABLO CANYON - UNITS 1 & 2 5.0-10 Unit 1 - Amendment No. 198, Unit 2 - Amendment No. 199,

Programs and Manuals 5.5 5.5 Programs and Manuals 5.5.9 Steam Generator (SG) Tube Inspection Program (continued)

3. The operational LEAKAGE performance criterion is specified in LCO 3.4.13, RCS Operational LEAKAGE.
c. Provisions for SG tube plugging repair criteria.

Tubes found by inservice inspection to contain flaws with a depth equal to or exceeding 40% of the nominal tube wall thickness shall be plugged.

d. Provisions for SG tube inspections.

Periodic SG tube inspections shall be performed. The number and portions of the tubes inspected and methods of inspection shall be performed with the objective of detecting flaws of any type (e.g., volumetric flaws, axial and circumferential cracks) that may be present along the length of the tube, from the tube-to tubesheet weld at the tube inlet to the tube-to-tubesheet weld at the tube outlet, and that may satisfy the applicable tube plugging repair criteria. The tube-to-tubesheet weld is not part of the tube. In addition to meeting the requirements of d.1, d.2, and d.3 below, the inspection scope, inspection methods, and inspection intervals shall be such as to ensure that SG tube integrity is maintained until the next SG inspection. An assessment of degradation assessment shall be performed to determine the type and location of flaws to which the tubes may be susceptible and, based on this assessment, to determine which inspection methods need to be employed and at what locations.

1. Inspect 100% of the tubes in each SG during the first refueling outage following SG installationreplacement.
2. After the first refueling outage following SG installation, inspect 100% of the tubes in each SG at least every 96 effective full power months, which defines the inspection period. Inspect 100% of the tubes at sequential periods of 144, 108, 72, and, thereafter, 60 effective full power months.

The first sequential period shall be considered to begin after the first inservice inspection of the SGs. In addition, inspect 50% of the tubes by the refueling outage nearest the midpoint of the period and the remaining 50% by the refueling outage nearest the end of the period. No SG shall operate for more than 72 effective full power months or three refueling outages (whichever is less) without being inspected.

3. If crack indications are found in any SG tube, then the next inspection for each affected and potentially affected SG for the degradation mechanism that caused the crack indication shall be at the next not exceed 24 effective full power months or one refueling outage (whichever is less). If definitive information, such as from examination of a pulled tube, diagnostic non-destructive testing, or engineering evaluation indicates that a crack-like indication is not associated with a crack(s), then the indication need not be treated as a crack.
e. Provisions for monitoring operational primary to secondary LEAKAGE.

DIABLO CANYON - UNITS 1 & 2 5.0-11 Unit 1 - Amendment No. 198, Unit 2 - Amen Unit 2 - Amendment No. 199,

Reporting Requirements 5.6 5.6 Reporting Requirements (continued) 5.6.10 Steam Generator (SG) Tube Inspection Report A report shall be submitted within 180 days after the initial entry into MODE 4 following completion of an inspection performed in accordance with the Specification 5.5.9, "Steam Generator (SG) Program." The report shall include:

a. The scope of inspections performed on each SG;,
b. The nondestructive examination techniques utilized for tubes with increased degradation susceptibility;
c. For each degradation mechanism found:
1. The nondestructive examination techniques utilized;
2. The location, orientation (if linear), measured size (if available), and voltage response for each indication. For tube wear at support structures less than 20 percent through-wall, only the total number of indications needs to be reported;
3. A description of the condition monitoring assessment and results, including the margin to the tube integrity performance criteria and comparison with the margin predicted to exist at the inspection by the previous forward-looking tube integrity assessment; and
4. The number of tubes plugged during the inspection outage.
d. An analysis summary of the tube integrity conditions predicted to exist at the next scheduled inspection (the forward-looking tube integrity assessment) relative to the applicable performance criteria, including the analysis methodology, inputs, and results;
b. Active degradation mechanisms found,
c. Nondestructive examination techniques utilized for each degradation mechanism,
d. Location, orientation (if linear), and measured sizes (if available) of service induced indications,
e. Number of tubes plugged during the inspection outage for each active degradation mechanism, ef. Theotal number and percentage of tubes plugged to date, and the effective plugging percentage in each SG; and
f. The results of any SG secondary side inspections.
g. The results of condition monitoring, including the results of tube pulls and in-situ testing.

DIABLO CANYON - UNITS 1 & 2 5.0-23 Unit 1 - Amendment No. 198, Unit 2 - Amendment No. 199,

Enclosure Attachment 2 PG&E Letter DCL-22-011 Revised Technical Specification Pages Remove Page Insert Page 3.4-37 3.4-37 3.4-38 3.4-38 5.0-10 5.0-10 5.0-11 5.0-11 5.0-23 5.0-23

SG Tube Integrity 3.4.17 3.4 REACTOR COOLANT SYSTEM (RCS) 3.4.17 Steam Generator (SG) Tube Integrity LCO 3.4.17 SG tube integrity shall be maintained.

AND All SG tubes satisfying the tube plugging criteria shall be plugged in accordance with the Steam Generator Program.

APPLICABILITY: MODES 1, 2, 3, and 4.

ACTIONS

NOTE-------------------------------------------------------------

Separate Condition entry is allowed for each SG tube.

CONDITION REQUIRED ACTION COMPLETION TIME A. One or more SG tubes A.1 Verify tube integrity of the 7 days satisfying the tube plugging affected tube(s) is criteria and not plugged in maintained until the next accordance with the Steam refueling outage or SG Generator Program. tube inspection.

AND A.2 Plug the affected tube(s) in Prior to entering accordance with the Steam MODE 4 following the Generator Program. next refueling outage or SG tube inspection B. Required Action and B.1 Be in MODE 3. 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> associated Completion Time of Condition A not AND met. B.2 Be in MODE 5. 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br /> OR SG tube integrity not maintained.

DIABLO CANYON - UNITS 1 & 2 3.4-37 Unit 1 - Amendment No. 194, Unit 2 - Amendment No. 195,

SG Tube Integrity 3.4.17 SURVEILLANCE REQUIREMENTS SURVEILLANCE FREQUENCY SR 3.4.17.1 Verify SG tube integrity in accordance with the Steam In accordance with Generator Program. the Steam Generator Program SR 3.4.17.2 Verify that each inspected SG tube that satisfies the Prior to entering tube plugging criteria is plugged in accordance with MODE 4 following the Steam Generator Program. a SG tube inspection DIABLO CANYON - UNITS 1 & 2 3.4-38 Unit 1 - Amendment No. 194, Unit 2 - Amendment No. 195,

Programs and Manuals 5.5 5.5 Programs and Manuals (continued) 5.5.9 Steam Generator (SG) Program An SG Program shall be established and implemented to ensure that SG tube integrity is maintained. In addition, the SG Program shall include the following:

a. Provisions for condition monitoring assessments. Condition monitoring assessment means an evaluation of the as found condition of the tubing with respect to the performance criteria for structural integrity and accident induced leakage. The as found condition refers to the condition of the tubing during an SG inspection outage, as determined from the inservice inspection results or by other means, prior to the plugging of tubes. Condition monitoring assessments shall be conducted during each outage during which the SG tubes are inspected or plugged to confirm that the performance criteria are being met.
b. Performance criteria for SG tube integrity. SG tube integrity shall be maintained by meeting the performance criteria for tube structural integrity, accident induced leakage, and operational LEAKAGE.
1. Structural integrity performance criterion: All in-service SG tubes shall retain structural integrity over the full range of normal operating conditions (including startup, operation in the power range, hot standby, and cool down), all anticipated transients included in the design specification, and design basis accidents. This includes retaining a safety factor of 3.0 against burst under normal steady state full power operation primary-to-secondary pressure differential and a safety factor of 1.4 against burst applied to the design basis accident primary-to-secondary pressure differentials. Apart from the above requirements, additional loading conditions associated with the design basis accidents, or combination of accidents in accordance with the design and licensing basis, shall also be evaluated to determine if the associated loads contribute significantly to burst or collapse. In the assessment of tube integrity, those loads that do significantly affect burst or collapse shall be determined and assessed in combination with the loads due to pressure with a safety factor of 1.2 on the combined primary loads and 1.0 on axial secondary loads.
2. Accident induced leakage performance criterion: The primary to secondary accident induced leakage rate for any design basis accident, other than a SG tube rupture, shall not exceed the leakage rate assumed in the accident analysis in terms of total leakage rate for all SGs and leakage rate for an individual SG. Except during a SG tube rupture, leakage is also not to exceed 1 gallon per minute per SG.

(continued)

DIABLO CANYON - UNITS 1 & 2 5.0-10 Unit 1 - Amendment No. 198, Unit 2 - Amendment No. 199,

Programs and Manuals 5.5 5.5 Programs and Manuals 5.5.9 Steam Generator (SG) Program (continued)

3. The operational LEAKAGE performance criterion is specified in LCO 3.4.13, RCS Operational LEAKAGE.
c. Provisions for SG tube plugging criteria. Tubes found by inservice inspection to contain flaws with a depth equal to or exceeding 40% of the nominal tube wall thickness shall be plugged.
d. Provisions for SG tube inspections. Periodic SG tube inspections shall be performed. The number and portions of the tubes inspected and methods of inspection shall be performed with the objective of detecting flaws of any type (e.g., volumetric flaws, axial and circumferential cracks) that may be present along the length of the tube, from the tube-to tubesheet weld at the tube inlet to the tube-to-tubesheet weld at the tube outlet, and that may satisfy the applicable tube plugging criteria. The tube-to-tubesheet weld is not part of the tube. In addition to meeting the requirements of d.1, d.2, and d.3 below, the inspection scope, inspection methods, and inspection intervals shall be such as to ensure that SG tube integrity is maintained until the next SG inspection. A degradation assessment shall be performed to determine the type and location of flaws to which the tubes may be susceptible and, based on this assessment, to determine which inspection methods need to be employed and at what locations.
1. Inspect 100% of the tubes in each SG during the first refueling outage following SG installation.
2. After the first refueling outage following SG installation, inspect 100% of the tubes in each SG at least every 96 effective full power months, which defines the inspection period.
3. If crack indications are found in any SG tube, then the next inspection for each affected and potentially affected SG for the degradation mechanism that caused the crack indication shall be at the next refueling outage. If definitive information, such as from examination of a pulled tube, diagnostic non-destructive testing, or engineering evaluation indicates that a crack-like indication is not associated with a crack(s), then the indication need not be treated as a crack.
e. Provisions for monitoring operational primary to secondary LEAKAGE.

DIABLO CANYON - UNITS 1 & 2 5.0-11 Unit 1 - Amendment No. 198, Unit 2 - Amen Unit 2 - Amendment No. 199,

Reporting Requirements 5.6 5.6 Reporting Requirements (continued) 5.6.10 Steam Generator Tube Inspection Report A report shall be submitted within 180 days after the initial entry into MODE 4 following completion of an inspection performed in accordance with the Specification 5.5.9, "Steam Generator (SG) Program." The report shall include:

a. The scope of inspections performed on each SG;
b. The nondestructive examination techniques utilized for tubes with increased degradation susceptibility;
c. For each degradation mechanism found:
1. The nondestructive examination techniques utilized;
2. The location, orientation (if linear), measured size (if available), and voltage response for each indication. For tube wear at support structures less than 20 percent through-wall, only the total number of indications needs to be reported;
3. A description of the condition monitoring assessment and results, including the margin to the tube integrity performance criteria and comparison with the margin predicted to exist at the inspection by the previous forward-looking tube integrity assessment; and
4. The number of tubes plugged during the inspection outage.
d. An analysis summary of the tube integrity conditions predicted to exist at the next scheduled inspection (the forward-looking tube integrity assessment) relative to the applicable performance criteria, including the analysis methodology, inputs, and results;
e. The number and percentage of tubes plugged to date, and the effective plugging percentage in each SG; and
f. The results of any SG secondary side inspections.

DIABLO CANYON - UNITS 1 & 2 5.0-23 Unit 1 - Amendment No. 198, Unit 2 - Amendment No. 199,

Enclosure Attachment 3 PG&E Letter DCL-22-011 Proposed Technical Specification Bases Changes (Mark-Up)

For Information Only

Steam Generator (SG) Tube Integrity B 3.4.17 BASES (continued)

APPLICABLE The steam generator tube rupture (SGTR) accident is the limiting SAFETY design basis event for SG tubes and avoiding an SGTR is the basis for ANALYSES this Specification. The analysis of a SGTR event assumes a primary to secondary LEAKAGE rate of 0.75 gpm from the intact SGs plus the leakage rate associated with a double-ended rupture of a single tube.

The SGTR radiological dose analysis assumes loss of off-site power at the time of reactor trip with no subsequent condenser cooling available.

The SG PORV for the SG that has sustained the tube rupture is assumed to fail open for 30 minutes, at which time the operator closes the block valve to the PORV. The SGTR radiological dose analysis assumes the contaminated secondary fluid is released briefly to the atmosphere from all the PORVs following reactor trip, is released from the ruptured SG PORV for 30 minutes, is released from the intact SG PORVs during the cooldown, and is released from all PORVs following cooldown until termination of the event.

The analysis for design basis accidents and transients other than a SGTR assume the SG tubes retain their structural integrity (i.e., they are assumed not to rupture.) The steam discharge to the atmosphere is based on the total primary to secondary LEAKAGE from all SGs of 0.75 gpm under accident conditions. For accidents that do not involve fuel damage, the primary coolant activity level of DOSE EQUIVALENT I-131 is assumed to be equal to the LCO 3.4.16, RCS Specific Activity, limits. For accidents that assume fuel damage, the primary coolant activity is a function of the amount of activity released from the damaged fuel. The dose consequences of these events are within the limits of GDC 19 (Ref. 2), 10 CFR 50.67 (Ref. 3) and RG 1.183 (Ref.

7).

Steam generator tube integrity satisfies Criterion 2 of 10 CFR 50.36(c)(2)(ii).

LCO The LCO requires that SG tube integrity be maintained. The LCO also requires that all SG tubes that satisfy the plugging repair criteria be plugged in accordance with the Steam Generator Program.

During an SG inspection, any inspected tube that satisfies the Steam Generator Program plugging repair criteria is removed from service by plugging. If a tube was determined to satisfy the plugging repair criteria but was not plugged, the tube may still have tube integrity.

(continued)

DIABLO CANYON - UNITS 1 & 2 Rev 12A Page 107 of 112

Steam Generator (SG) Tube Integrity B 3.4.17 BASES (continued)

ACTIONS The ACTIONS are modified by a Note clarifying that the Conditions may be entered independently for each SG tube. This is acceptable because the Required Actions provide appropriate compensatory actions for each affected SG tube. Complying with the Required Actions may allow for continued operation, and subsequent affected SG tubes are governed by subsequent Condition entry and application of associated Required Actions.

A.1 and A.2 Condition A applies if it is discovered that one or more SG tubes examined in an inservice inspection satisfy the tube plugging repair criteria but were not plugged in accordance with the Steam Generator Program as required by SR 3.4.17.2. An evaluation of SG tube integrity of the affected tube(s) must be made. Steam generator tube integrity is based on meeting the SG performance criteria described in the Steam Generator Program. The SG plugging repair criteria define limits on SG tube degradation that allow for flaw growth between inspections while still providing assurance that the SG performance criteria will continue to be met. In order to determine if a SG tube that should have been plugged has tube integrity, an evaluation must be completed that demonstrates that the SG performance criteria will continue to be met until the next refueling outage or SG tube inspection. The tube integrity determination is based on the estimated condition of the tube at the time the situation is discovered and the estimated growth of the degradation prior to the next SG tube inspection. If it is determined that tube integrity is not being maintained, Condition B applies.

A Completion Time of 7 days is sufficient to complete the evaluation while minimizing the risk of plant operation with a SG tube that may not have tube integrity.

If the evaluation determines that the affected tube(s) have tube integrity, Required Action A.2 allows plant operation to continue until the next refueling outage or SG inspection provided the inspection interval continues to be supported by an operational assessment that reflects the affected tubes. However, the affected tube(s) must be plugged prior to entering MODE 4 following the next refueling outage or SG inspection. This Completion Time is acceptable since operation until the next inspection is supported by the operational assessment.

(continued)

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Steam Generator (SG) Tube Integrity B 3.4.17 BASES ACTIONS B.1 and B.2 (continued)

If the Required Actions and associated Completion Times of Condition A are not met or if SG tube integrity is not being maintained, the reactor must be brought to MODE 3 within 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> and MODE 5 within 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br />.

The allowed Completion Times are reasonable, based on operating experience, to reach the desired plant conditions from full power conditions in an orderly manner and without challenging plant systems.

SURVEILLANCE SR 3.4.17.1 REQUIREMENTS During shutdown periods the SGs are inspected as required by this SR and the Steam Generator Program. NEI 97-06, Steam Generator Program Guidelines (Ref. 1), and its referenced EPRI Guidelines, establish the content of the Steam Generator Program. Use of the Steam Generator Program ensures that the inspection is appropriate and consistent with accepted industry practices.

During SG inspections a condition monitoring assessment of the SG tubes is performed. The condition monitoring assessment determines the as found condition of the SG tubes. The purpose of the condition monitoring assessment is to ensure that the SG performance criteria have been met for the previous operating period.

The Steam Generator Program determines the scope of the inspection and the methods used to determine whether the tubes contain flaws satisfying the tube plugging repair criteria. Inspection scope (i.e., which tubes or areas of tubing within the SG are to be inspected) is a function of existing and potential degradation locations. The Steam Generator Program also specifies the inspection methods to be used to find potential degradation. Inspection methods are a function of degradation morphology, nondestructive examination (NDE) technique capabilities, and inspection locations.

The Steam Generator Program defines the Frequency of SR 3.4.17.1.

The Frequency is determined by the operational assessment and other limits in the SG examination guidelines (Ref. 6). The Steam Generator Program uses information on existing degradations and growth rates to determine an inspection Frequency that provides reasonable assurance that the tubing will meet the SG performance criteria at the next scheduled inspection.

(continued)

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Steam Generator (SG) Tube Integrity B 3.4.17 BASES SURVEILLANCE In addition, Specification 5.5.9 contains prescriptive requirements REQUIREMENTS concerning inspection intervals to provide added assurance that the SG (continued) performance criteria will be met between scheduled inspections. If crack indications are found in any SG tube, the maximum inspection interval for all affected and potentially affected SGs is restricted by Specification 5.5.9 until subsequent inspections support extending the inspection interval.

SR 3.4.17.2 During an SG inspection, any inspected tube that satisfies the Steam Generator Program plugging repair criteria is removed from service by plugging. The tube plugging repair criteria delineated in Specification 5.5.9 are intended to ensure that tubes accepted for continued service satisfy the SG performance criteria with allowance for error in the flaw size measurement and for future flaw growth. In addition, the tube plugging repair criteria, in conjunction with other elements of the Steam Generator Program, ensure that the SG performance criteria will continue to be met until the next inspection of the subject tube(s).

Reference 1 provides guidance for performing operational assessments to verify that the tubes remaining in service will continue to meet the SG performance criteria.

The Frequency of prior to entering MODE 4 following a SG inspection ensures that the Surveillance has been completed and all tubes meeting the plugging repair criteria are plugged prior to subjecting the SG tubes to significant primary to secondary pressure differential.

REFERENCES 1. NEI 97-06, Steam Generator Program Guidelines.

2. 10 CFR 50 Appendix A, GDC 19, 1999.
3. 10 CFR 50.67.
4. ASME Boiler and Pressure Vessel Code,Section III, Subsection NB.
5. Draft Regulatory Guide 1.121, Basis for Plugging Degraded Steam Generator Tubes, August 1976.
6. EPRI, Pressurized Water Reactor Steam Generator Examination Guidelines.
7. Regulatory Guide 1.183, July 2000.

DIABLO CANYON - UNITS 1 & 2 Rev 12A Page 112 of 112

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