DCL-13-114, Response to November 1, 2013, Request for Additional Information Regarding Recommendation 2.3 Seismic

Response to November 1, 2013, Request for Additional Information Regarding Recommendation 2.3 Seismic

ML13337A449
Person / Time
Site:	Diablo Canyon
Issue date:	12/02/2013
From:	Allen B Pacific Gas & Electric Co
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
PG&E Letter DCL-13-114
Download: ML13337A449 (15)

Text

Pacific Gas and Electric Company December 2, 2013 PG&E Letter DCL-13-114 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk 11555 Rockville Pike Rockville, MD 20852 Docket No. 50-275, OL-DPR-80 Docket No. 50-323, OL-DPR-82 Diablo Canyon Units 1 and 2 Barry S. Allen Site Vice President Diablo Canyon Power Plant Mail Code 104/6 P. 0. Box 56 Avila Beach, CA 93424 805.545.4888 Internal: 6 91.4888 Fax: 805.545.6445 10 CFR 50.54(f)

Response to November 1. 2013. Request for Additional Information Regarding Recommendation 2.3 Seismic

References:

1. NRC Letter, "Request for Information Pursuant to Title 10 of the Code of Federal Regulations 50.54(f) Regarding Recommendations 2.1, 2.3, and 9.3 of the Near-Term Task Force Review of Insights from the Fukushima Dai-ichi Accident," dated March 12, 2012

2. PG&E Letter DCL-12-118, "Response to Request for Information Pursuant to 10 CFR 50.54(f) Regarding Recommendation 2.3 Seismic Unit 1,"dated November 27, 2012

3. PG&E Letter DCL-12-119, "Response to Request for Information Pursuant to 10 CFR 50.54(f) Regarding Recommendation 2.3 Seismic Unit 2," dated November 27, 2012

4. PG&E Letter DCL-13-054, "Response Amendment to Request for Information Pursuant to 10 CFR 50.54(f) Regarding Recommendation 2.3 Seismic," dated May 22, 2013

Dear Commissioners and Staff:

On March 12, 2012, the Nuclear Regulatory Commission (NRC) staff issued Reference 1 to Pacific Gas and Electric Company (PG&E) requesting additional information per Title 10 of the Code of Federal Regulations, Section 50.54(f).

Reference 1 requested that licensees conduct seismic hazard walkdowns to verify the plant configuration is within their current licensing basis. PG&E Letter DCL-12-066, "Pacific Gas and Electric Company's 120-Day Response to NRC Request for Information Pursuant to 10 CFR 50.54(f) Regarding the Seismic Aspects of Recommendation 2.3 of the Near-Term Task Force Review of Insights from the A

member of the STARS (Strategic Teaming and Resource Sharing)

Alliance Callaway

• Comanche Peak

• Diablo Canyon

• Palo Verde

• San Onofre

• South Texas Project

• Wolf Creek

Document Control Desk December 2, 2013 Page 2 PG&E Letter DCL-13-114 Fukushima Dai-lchi Accident," dated July 10, 2012, confirmed that PG&E would use EPRI 1025286, as endorsed by NRC Letter, "Endorsement of Electric Power Research Institute (EPRI) Draft Report 1025286, 'Seismic Walkdown Guidance,'"

dated May 31, 2012.

References 2 and 3 provided PG&E's responses to Recommendation 2.3 seismic for Diablo Canyon Power Plant Units 1 and 2, respectively. Reference 4 provided amendments to Reference 3 and the basis for the amendments.

On November 1, 2013, the NRC staff issued a request for additional information (RAI) associated with Near-Term Task Force Recommendation 2.3, seismic evaluations. of this letter provides PG&E's response to the November 1, 2013, RAis. provides replacement checklists and licensing basis evaluations that were updated during the RAI response development.

PG&E is making a regulatory commitment (as defined by NEI 99-04) in Enclosure 3 of this letter. This letter includes no revisions to existing regulatory commitments.

If you have any questions, or require additional information, please contact Mr. Patrick Nugent at (805) 781-9786.

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

Executed on December 2, 2013.

Sincerely,

!~e! 4?L_

Site Vice President dmfn/SAPN 50589032 Enclosures cc:

Diablo Distribution cc:/enc:

Brian J. Benney, NRR Project Manager Marc L. Dapas, NRC Region IV Administrator Thomas R. Hipschman, NRC, Senior Resident Inspector Eric J. Leeds, NRC/NRR Director A

member of the STARS (Strategic Teaming and Resource Sharing)

Alliance Callaway

• Comanche Peak

• Diablo Canyon

• Palo Verde

• San Onofre

• South Texas Project

• Wolf Creek PG&E Letter DCL-13-114 Page 1 of 7 Pacific Gas and Electric Company Response to Nuclear Regulatory Commission Request for Additional Information Associated with Near-Term Task Force Recommendation 2.3, Seismic Walkdowns, dated November 1, 2013 Conduct of the wa/kdowns, determination of potentially adverse seismic conditions (PASCs), dispositioning of issues, and reporting As a result of the audits and walkdown report reviews, the NRC staff noted that licensees' interpretations of the seismic walkdown guidance varied, which resulted in meaningful differences in the process used to disposition identified issues and in the documentation that was provided to the NRC staff. In particular, the application of engineering judgment in determining what constituted a potentially adverse seismic condition (PASC); the threshold for conducting licensing basis evaluations (LBEs);

and determining what information was to be reported to the NRC staff varied.

The NRC staff intended that conditions initially marked No (N) or Unknown (U) in the field by the seismic walkdown engineers (SWEs) for which an analysis or calculation was petformed would be considered as PASCs and that an analysis or calculation constituted a LBE. The walkdown guidance allows for analysis as part of engineering judgment; however, the intent was to allow for only simple analyses that could be readily petformed in support of engineering judgment. Further, the walkdown activities were intended to allow for transparency in the licensee's process to demonstrate that PASCs were appropriately identified, that they were addressed in an appropriate manner and the basis documented such that the current condition of the plant was clearly consistent with the CLB with regards to seismic capability.

During the audits, the NRC staff identified examples of field observations that were deemed not to be PASCs. However, the basis for the determination was not clearly recorded. In some cases, the field checklists were amplified by noting that the basis was engineering judgment. During site audit discussions, the staff was able to trace the basis for the engineering judgments and found that many cases they were appropriate.

It is expected that these situations would not be included in the walkdown report.

There were other situations that a PASC and LBE were not reported; however, the NRC staff found during the audit that a calculation, analysis (more than just simple), or evaluation was conducted but informally. An example is a confirmatory calculation petformed to demonstrate that six anchor bolts out of eight was not a seismically adverse condition. Another example would be an analysis to demonstrate that an existing, slightly short weld was as seismically sound as the prescribed weld length in the plant design documentation. The staff expected these types of conditions and evaluations to be captured in the licensee's normal plant processes (e.g., condition report or corrective action program (CAP)), and also reported in the walkdown report, since they were potent!ally adverse seismic conditions that required more than applying

judgment or simple analysis to address.

PG&E Letter DCL-13-114 Page 2 of 7 The NRC staff also found that the process that was used to deal with a field observation that was deemed to be a PASC was also not completely described or captured in the report. In many cases, the licensee reported that an LBE was not petformed. However, during the audits, it was clear that an LBE (or an equivalent determination method) was petformed and used in determining whether a PASC should be entered into the CAP.

The staff expects that these conditions would be reported in the walkdown report.

On the whole, through the audits, the NRC staff found that it was able to conclude that the intent of the guidance was met when the licensee's overall process was completely explained, the information was updated to reflect the actual process, and results were updated. The self-assessments conducted by the licensees of the audited plants also identified the lapse in the description of the process used by the licensee to identify a PASC and disposition it.

Therefore, in order to clarify the process that was followed, please provide a description of the overall process used by the licensee (and its contractors) to evaluate observations identified in the field by the SWEs. The process should include how a field observation was determined to be a PASC or not and how the bases for determinations were recorded. Once a determination was made that an observation was a PASC, describe the process for creating a condition report (or other tracking mechanism),

petforming the LBE (or other determination method), and the resultant action, such as entering it into the CAP, or documenting the result and basis.

Also, in order to confirm that the reported information supports concluding that the plant meets the CLB, please follow one of the following three acceptable alternatives:

(a)

Provide a supplement to the table or text from the original walkdown report, if needed, to include similar conditions as the above examples and situations and for conditions for which a calculation, analysis (if more than a simple analysis), or evaluation was used for a determination. The supplement should include a short description of each condition, how it was dispositioned and the basis for the disposition, as follows: 1) for each condition that was entered into the CAP, provide the CAP reference number, initiation date, and (if known) the planned completion date, or

2) for all other conditions, provide the result of the LBE (or other determination method), the basis for the result, and how (or where) the result was captured in the plant's documentation or existing plant process.

(b)

Following the plant's standard procedures, confirm that a new CAP entry has been made to verify if appropriate actions were taken when reporting and dispositioning identified PASCs (including conditions for which a calculation, analysis (if more than a simple analysis), or evaluation was used for a determination). The eventual CAP closeout, including the PG&E Letter DCL-13-114 Page 3 of 7 process followed and actions taken, should be in sufficient detail to enable NRC resident inspectors to follow up.

(c)

If no new conditions are identified for addition to the supplement or the CAP entry mentioned above is deemed not necessary, provide a statement of confirmation that all potentially seismic adverse conditions (including conditions for which a calculation, analysis (if more than a simple analysis), or evaluation was used for a determination) identified during the walkdowns and walk-bys were addressed and included in the report to the NRC.

PG&E Response to RAI-1 A summary of the walkdown process was provided in Pacific Gas and Electric Company (PG&E) Letter DCL-12-118, "Response to Request for Information Pursuant to 10 CFR 50.54(f) Regarding Recommendation 2.3 Seismic Unit 1,"dated November 27, 2012, (Reference 1) and PG&E Letter DCL-12-119, "Response to Request for Information Pursuant to 1 0 CFR 50.54(f) Regarding Recommendation 2.3 Seismic Unit 2," dated November 27, 2012 (Reference 2). As a supplement to the process described in References 1 and 2, the overall process used by PG&E and its contractors to evaluate observations identified in the field by the seismic walkdown engineers (SWEs) was as follows:

After completing the walkdowns, the seismic walkdown checklists (SWCs) and area walk-by checklists (AWCs) were reviewed and relevant information, such as the checklist number, checklist overall status (Yes [Y], No [N], or Undetermined [U]), and a description of each preliminary issue (issue) identified during the performance of the walkdown (issues are associated with questions on the checklist that had a preliminary answer of U or N) was placed into a tracking spreadsheet (Tracker). The Tracker also had provisions for documenting the Corrective Action Program (CAP) number (Notification) and whether an issue was a potentially adverse seismic condition (PASC).

The licensing basis reviewer (LBR), as described in References 1 and 2, Attachment A, reviewed each issue that was entered into the Tracker in accordance with the Diablo Canyon Power Plant (DCPP) CAP to determine if the issue needed to be entered into the CAP. If this review determined that a CAP entry was required, a Notification was written and the number entered into the Tracker.

The LBR, working with the SWE and other DCPP engineering groups when necessary, then reviewed each issue to determine the appropriate disposition of the issue. Since the LBR had access to information that was not available to the SWEs while in the field, such as calculations, drawings, test reports, and historical CAP entries, it was possible for the LBR working with SWEs to make a more informed decision regarding the impact of the issue on the adequacy of the affected structure, system, or component (SSC) and the acceptability of the as-found conditions.

PG&E Letter DCL-13-114 Page 4 of 7 (a)

If the as-found condition of the SSC was not bounded by design and licensing requirements, an assessment, based on engineering judgment or an informal calculation was performed to determine the impact of the as-found condition on the ability of the sse to perform its required function. The results of this assessment were used to determine functionality and documented in the CAP. The answer to the question associated with the issue could be changed from a U to an N, or remained an N on the checklist.

(b)

If the as-found condition of the SSC was in accordance with design and licensing basis, a functionality assessment was not required and it was recommended that the answer to the question associated with the issue be changed from a U or an N to a Y on the checklist.

The results of this review, including any changes to the answers on a checklist and the basis for the changes were coordinated with the SWEs and documented on the checklist, either in the remarks/comments section on the checklist or a separate Licensing Basis Evaluation (LBE) form that was attached to the checklist. As described on Page 12 of References 1 and 2, a LBE was performed for each of the potentially adverse seismic-related conditions and other issues to determine the component's ability to perform its required function. The disposition of the issue was also documented in the Tracker.

The LBR used Electric Power Research Institute Technical Report 1025286, "Seismic Walkdown Guidance for Resolution of Fukushima Near-Term Task Force Recommendation 2.3: Seismic," (Reference 3) to determine if identified issues were considered "potentially seismically adverse," which included adverse anchorage conditions, adverse seismic spatial interactions, or other seismic conditions. Since the SWE documented all issues without regard to whether they were PASCs, the LBR used Reference 3, Section 8 as guidance to assign each issue to one of the following groups:

(1)

Degraded The as-found condition of the SSC was degraded. This group included the following subgroups:

Corrosion (e.g., rust on steel, corrosion on copper)

Other (e.g., coatings failure, loose or damaged hardware)

(2)

Configuration The as-found configuration of the SSC was not in conformance with the design and licensing basis (e.g., undersized or missing bolts, undersized or missing welds, incorrect member sizes, improper installation details)

(3)

Spatial Interaction PG&E Letter DCL-13-114 Page 5 of7 The as-found configuration of the other components in the vicinity of the SSC could adversely interact with the SSC during a seismic event. The group included the following subgroups:

Spatial (e.g., physical impact between components)

Fire (e.g., source of fire, such as flammable liquids or gases)

Flood (e.g., sources of water)

Housekeeping (e.g., unsecured ladders, tools, carts, trash cans, supplies)

Other (issues that did not fit one of the above subgroups)

The following criteria were used to determine which issues were considered to be a PASC:

(1)

Potentially Adverse Seismic Condition: the degraded, configuration, or spatial interaction issue potentially impacts the seismic qualification status of an SSC (e.g., significant corrosion, missing fasteners, undersized fasteners, potential for damage from spatial interaction that would impair functionality, etc.).

(2)

Non-Potentially Adverse Seismic Condition: the degraded, configuration, or spatial interaction issue does not impact the seismic qualification status of an SSC (e.g., surface corrosion, damaged insulation, housekeeping issues, water leakage, degradation of non-seismic components).

The results on the application of these criteria were entered in the Tracker for each issue, where a Y entry in the PASC column indicated that the issue was potentially seismically adverse.

Issues that were classified as PASCs were summarized in References 1 and 2, Attachment G, "Potentially Adverse Seismic Conditions Entered into the Corrective Action Program." PG&E Letter DCL-13-054, "Response Amendment to Request for Additional Information Pursuant to 10 CFR 50.54(f) Regarding Recommendation 2.3 Seismic," dated May 22, 2013 (Reference 4), Attachment G, contained an update to the DCPP Unit 2 PASCs based on the results of the walkdowns of the SSCs that were classified as inaccessible at the time of the walkdowns, as documented in Reference 2, Attachment H. Issues identified during the walkdowns that were not classified as PASCs were not in eluded in References 1, 2, and 4.

In order to confirm that the reported information supports concluding that the plant meets the current licensing basis, PG&E will follow alternative (b) to this RAI. In accordance with the DCPP CAP, PG&E initiated a new Notification to verify that appropriate actions were taken when reporting and dispositioning PASCs identified in PG&E Letter DCL-13-114 Page 6 of 7 References 1, 2, and 4 (including conditions for which a calculation, analysis (if more than a simple analysis), or evaluation was used for a determination. The closeout of this Notification will include or provide a reference to the process followed and actions taken for each PASC.

Conduct of the Peer Review Process As a result of the walkdown report reviews, the NRC staff noted that some descriptions of the peer reviewers and the peer review process that was followed were varied and, in some cases, unclear. In some cases, the staff could not confirm details of the process, such as if the entire process was reviewed by the peer review team, who were the peer reviewers, what was the role of each peer reviewer, and how the reviews affected the work, if at all, described in the walkdown guidance.

Therefore, in order to clarify the peer review process that was actually used, please confirm whether the following information on the peer review process was provided in the original submittal, and if not, provide the following.

(a)

Confirmation that the activities described in the walkdown guidance on page 6-1 were assessed as part of the peer review process (b)

A complete summary of the peer review process and activities. Details should include confirmation that any individual involved in petforming any given walkdown activity was not a peer reviewer for that same activity. If there were cases in which peer reviewers reviewed their own work, please justify how this is in accordance with the objectives of the peer review efforts.

Also, if there are differences from the original submittal, please provide a description of the above information. If there are differences in the review areas or the manner in which the peer reviews were conducted, describe the actual process that was used.

PG&E Response to RAI-2 References 1 and 2, Attachment K, provided the peer review process used at DCPP.

References 1 and 2, Attachment A, "Seismic Walkdown Equipment List Team Personnel Qualifications," provide the names of the peer reviewers who performed the task and their role.

PG&E used a peer review team to review all SWCs, AWCs, and LBEs. This team approach ensured that no individual was the sole reviewer of their own work. The peer reviewers are listed in References 1 and 2, Attachment A.

References PG&E Letter DCL-13-114 Page 7 of?

1.

PG&E) Letter DCL-12-118, "Response to Request for Information Pursuant to 10 CFR 50.54(f) Regarding Recommendation 2.3 Seismic Unit 1,"dated November 27, 2012

2.

PG&E Letter DCL-12-119, "Response to Request for Information Pursuant to 10 CFR 50.54(f) Regarding Recommendation 2.3 Seismic Unit 2," dated November 27, 2012

3.

Electric Power Research Institute, Technical Report No. 1025286, "Seismic Walkdown Guidance for Resolution of Fukushima Near-Tern Task Force Recommendation 2.3: Seismic," dated June 2012

4.

PG&E Letter DCL-13-054, "Response Amendment to Request for Information Pursuant to 10CFR50.54(f) Regarding Recommendation 2.3 Seismic Unit 2,"

dated May 22, 2013 PG&E Letter DCL-13-114 Updated Checklists and LBE Checklist Changes(a) 2-BFS-33 Replaces checklist and removes the related Licensing Basis Evaluation (LBE) that was submitted in Pacific Gas and Electric Company (PG&E) Letter DCL-12-119, "Response to Request for Information Pursuant to 10 CFR 50.54(f) Regarding Recommendation 2.3 Seismic Unit 2," dated November 27, 2012.

DC-1-04-P-VOA-MS-1-FCV-41 Replaces checklist and LBE Attachment 2 to the checklist, submitted in PG&E Letter DCL-12-118, "Response to Request for Information Pursuant to 10 CFR 50.54(f) Regarding Recommendation 2.3 Seismic Unit 1,"dated November 27, 2012.

(a)

All changes are indicated on the attached checklists and LBE with revision bars.

Area Walk-By Checklist (AWC)

Status Y

• Location:

Building: Auxiliary Floor El. 140 Room, Area:

2-BFS-33 J<e.\\J, :1.

Instructions for Completing Checklist This checklist may be used to document the results of the area walk-by near one or more SWEL. items. The space below each of the following questions may be used to record the results of judgements and findings. Additional space is provided at the end of this ohecl<list for documenting other comments.

1. Does the anchorage of equipment in the area appear to be free of potentially adverse seismic conditions (if visible Y

without necessarily opening cabinets)

2. Does anchorage of equipment in the area appear to be free of significant degraded conditions?

Heavily corroded frame between the air filters and the fan room (support for e.uxifiaty steam heating coils), see photo on page 3. Frame was abandoned In place per Notifioatlon No. 50041855 and Design Change Package No. 1000000191. (Not safety related).

3.Based on vlsuallnspeclion from the floor. do the cable/conduit raceways and HVAC ductlng appear to be free of potentially adverse seismic conditions (e.g., condition of supports is adequate and fill conditions of cable trays appear to be inside acceptable limits)?

4. Does it appear that the area Is free of potentially adverse seismic spatial Interactions with other e*quipment in the area( e.g., ceiling tiles and lighting)?

Lights in the room are we11 supported with no open hooks. A chain hung light Is outside of the room (near the air filters) but no Interaction issues with nearby equipment.

5. Does it appear that the area is free of potentially adverse seismic interactions that could cause flooding or spray In the area?

Fire piping in the room is adequately supported.

y y

y y

6. Does it appear tnat the area Is free of potentially adverse seismic interactions that could cause fire in the area?

Y No flammable sources In the room.

7. D.oes it appear that the area Is free of potentially adverse seismic Interactions associated with housekeeping practice~. storage of portable equipment, and temporary installations (e.g. scaffolding, lead shielding)?

No temporary equipment or housekeeping issues noted.

y B. Have you looked for and found no other seismic conditions that could adversely affect the safety functions of the Y

equipment in the area?

Page 1 of4

Seismic Walkdown Clteddist (SWC) status:

N EquipmentiD No DC-1-04"P-VOA-MS-1-FCV-41 f<42.."

• 1-Equipment Class: I Equipment

Description:

MS Isolation Valves Location:

Building: Pipeway FloorEI. 115 Room, Area:

1-FCVft41 Manufacturer, model, Etc.

Amefek Instructions for Completing Checklist This checklist may be used to document the results of the Seismic Walkdown of an item of equipment on the SWEL. The space below each C?f the following questions may be used to record the results of judgements and findings. Additional space Is provided at the end of this checldist ror documenting other comments.

Anchorage

1. Is the anchorage configuration verification required (i.e, is the item one of the 50% ofSWEL items requiring such verification)?

2. Is the anchorage free of bent, broken, missing or loose hardware?

3. Is the anchorage free of corrosion that is more than mild surface oxidation?

4. Is the anchorage free of visible cracl<s in the concrete near the anchors?

5. Is the anchorage configuration consist~nt with plant documentation? (Note: This question only applies if the Item is one of the 50% for which an anchorage configuration verification Is required.)

6. Based on the above anchorage evaluations, is the anchorage free of potentially adverse seismic conditions?

Interaction Effects

7. Are soft targets free from impact by nearby equipment or structures?

1.5" clearance between bottom of valve and floor grating below on norlh side of pipe. On south side, clearance Is 112" at one location and 5132" at a second location. If main steam line moves significantly the valve actuator may Impact floor. See Attachment 1 for resolution.

8. Are overhead equipment, distribution systems, ceiling tiles, and lighting, and masonry block walls not likely to collapse onto the equipment?

Overhead floor grating may fall and impact valve instrumentation but the grating is judged to be adequately secured so falling is unlif<ely.

9. Do attached lines have adequate flexibility to avold damage?

10. Based on the above seismic interaction evaluations, is equipment free of potentially adverse seismic interaction effects?

Other Adverse Conditions

11. Have you lool<ed for and found no other seismic conditions that could adversely affect the safety function of the equipment?

Corrosion on valve body (not on actuator) was noted. Some flaking of corroslon product and pitting is visible.

Observed corrosion is acceptable. See Attachment 2 for disposition.

N y

y NfA N/A y

N y

y N

y Page 1 of 15 KAi J

Seismic Walkdown Checklist (SWC) status:

N

-~-

Equipment ID No DC~1-04-P~VOA-MS-1-ECV-41

'R.)J

• 1...

Equipment Class: Z Equipment

Description:

MS Isolation Valves Page 2 of 15

Seismic Walkdown Checklist (SWC)

Diablo Canyon Power Plant, Unit j_

Equipment No. DC-1-04-P-VOA-MS-1-FCV-41, Page 1 of 1 Licensing Basis Evaluation Issue:

Potentjal/y significant corrosion on body of valve no. FCV-41. Some flaking of corrosion product and pitting is visible.

Evaluation:

Based on visual examination, the corrosion is considered to be limited to surface corrosion and does not impact the ability* of the valve to perform its required design function or structural integrity. This condition does not impact the operation of DCPP.

Recommendations:

Cleaning, prepare, and recoat.

Notification Required: Yes (50594351)

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Evaluated by:

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Reviewed by:

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Regulatory Commitments PG&E Letter DCL-13-114 Pacific Gas and Electric Company is making the following commitment (as defined by NEI 99-04) in this submittal:

Commitment Due Date PG&E will follow alternative (b) to this RAI.

January 31, 2014 In accordance with the DCPP CAP, PG&E initiated a new Notification to verify that appropriate actions were taken when reporting and dispositioning PASCs identified in References 1, 2, and 4 (including conditions for which a calculation, analysis (if more than a simple analysis), or evaluation was used for a determination). The closeout of this Notification will include or provide a reference to the process followed and actions taken for each PASC.