L-2013-321, FPL St. Lucie Response to NRC Request for Additional Information Associated with Near-Term Task Force Recommendation 2.3, Seismic Walkdowns
| ML13346A157 | |
| Person / Time | |
|---|---|
| Site: | Saint Lucie  |
| Issue date: | 11/27/2013 |
| From: | Jensen J Florida Power & Light Co |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| L-2013-321 | |
| Download: ML13346A157 (9) | |
Text
0FPL.
November 27, 2013 L-2013-321 10 CFR 50.54(f)
U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-0001 RE:
St. Lucie Units 1 and 2 Docket Nos. 50-335 and 50-389 FPL St. Lucie Response To NRC Request for Additional Information Associated with Near-Term Task Force Recommendation 2.3, Seismic Walkdowns
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 (ML12073A348)
- 2.
FPL Letter L-2012-427 dateNovember 27, 2012, "Response to NRC 10 CFR 50.54(f)
Request for Information Regarding Near-Term Task Force Recommendation 2.3, Seismic"
- 3.
NRC Letter, "Request for Additional Information Associated with Near-Term Task Force Recommendation 2.3, Seismic Walkdowns," dated November 1, 2013 (ML13304B418)
On March 12,2012, the Nuclear Regulatory Commission (NRC) issued Reference 1 requesting information on several topics including information associated with Near-Term Task Force Recommendation 2.3 for a seismic walk down report. In Reference 2, Florida Power & Light (FPL) St. Lucie provided the requested information.
Subsequently, the Staff identified additional information, as documented in Reference 3, needed to complete its assessments. The Staff requested this information be submitted within 30 days from the date of Reference 3.
The attachment to this letter provides the information requested in Reference 3.
This letter makes no new commitments or changes to existing commitments.
Florida Power & Light Company 6501 S. Ocean Drive, Jensen Beach, FL 34957
L-2013-321 Page 2 If you have any questions or require additional information, please contact Ken Frehafer at (772) 467-7748.
I declare under penalty of perjury that the foregoing is true and correct.
Executed on November dv,
,52013 Site Vice President St. Lucie Plant Attachment
L-2013-321 Attachment Page 1 of 7 Supplement 1 to Florida Power & Light (FPL) St. Lucie Nuclear Station Seismic Walkdown Reports Request for Additional Information Associated with Near-Term Task Force Recommendation 2.3, Seismic Walkdowns, Dated November 1, 2013, Accession No. ML13304B418
L-2013-321 Attachment Page 2 of 7 This enclosure provides additional information requested by Reference I to add perspective to the Florida Power & Light St. Lucie (PSL) Nuclear Station Seismic Walkdown process used during the preparation of PSL Units 1 & 2 Seismic Walkdown Reports 12Q4116-RPT-001, Rev.0 and 12Q4116-R-002, Rev. 0 (Ref.2). Further clarification is specifically provided for the following topics:
- 1. Conduct of walkdowns, determination of potentially adverse seismic conditions (PASCs),
dispositioning of issues, and reporting.
- 2. Conduct of the peer review process.
NRC request for additional information:
(1) Conduct of walkdowns, determination of potentially adverse seismic conditions (PASCs), dispositioning of issues, and reporting (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."
PSL Response:
Section 5 of each Florida Power & Light St. Lucie Nuclear Station submittal report (Ref.2) provides an overview and detailed information regarding the conduct of the walkdowns. The walkdown process utilized met the EPRI industry guidance. The following provides additional supporting information regarding the walkdown process and use of engineering judgment:
The walkdowns at the St. Lucie Nuclear Station were performed by a two-person seismic walkdown engineer (SWE) team. Other St. Lucie professional staff participated in the walkdowns as part of the peer review process. All SWEs were qualified and trained as required by the EPRI guidance. The questions on each SWEL item checklist and each area walk-by checklist were assessed and answered during the field walkdowns. The SWE team first inspected the SWEL items. After the checklists of the SWEL items were complete, the SWEs performed the area walk-by inspection. This was done by the SWE team walking through and inspecting the area (approx. 35' from SWEL item) seismic attributes on the walk-by checklists to identify potential seismic interactions of area equipment or seismic housekeeping issues.
As stated in the submittal reports, the SWEs focused on identifying potentially adverse seismic conditions (PASCs) associated with the equipment - adverse anchorage conditions, spatial
L-2013-321 Attachment Page 3 of 7 interactions, and other conditions (such as loose or missing fasteners, etc.). In some cases, when a question could not be immediately answered, further review of plant documentation (drawing, existing evaluation, etc.) was performed as part of the checklist completion. The acceptability of potentially adverse seismic conditions is based on the expert opinion and judgment of the SWE.
The SWE are uniquely qualified to exercise this judgment because they have the requisite knowledge, experience, and training in the area of seismic/structural design, and have a thorough understanding of the plant's seismic design basis, design allowable loads, design margins and seismic spectral displacements. Thus, the expertise of the SWEs allows for potentially adverse conditions to be assessed against the seismic design basis using engineering judgment and/or simplified calculations.
The disposition of any PASC issues as not being a challenge to the seismic design basis was based on SWE engineering judgment or simple calculation documented on the checklist.
All potentially degraded, nonconforming, or unanalyzed conditions identified as a result of the seismic walkdowns were entered into the corrective action program (CAP). Evaluations of the identified conditions were completed and documented within the CAP. These evaluations determined that the Seismic Walkdowns resulted with no adverse seismic conditions, no adverse anchorage conditions and no other adverse seismic conditions associated with the items on the SWEL that challenged the licensing basis of the station (Units I & 2). The evaluations for items discovered during the Area Walk-Bys resulted in one condition which recommended increased spacing in order to provide additional margin for a potential adverse seismic spatial interaction on Unit 2 that was evaluated and documented in AR# 1812128.
Tables 5-2 & 5-3 of the Florida Power & Light St. Lucie Nuclear Station submittal reports (Ref.
- 2) provide a summary of issues identified during the equipment and area Seismic Walkdowns.
The equipment and area Seismic Walkdowns resulted in several conditions requiring action and each of these items were entered into the station's CAP by St. Lucie Plant site personnel. All of the identified concerns were assessed and determined to have no licensing basis or current operability issues.
Table 6-1 of the Florida Power & Light St. Lucie Nuclear Station submittal report (Ref. 2) listed the PASCs for the seismic licensing basis evaluations that were performed. These evaluations were completed and documented within the corresponding condition reports and shown in Table 6-1 of the reports. It should be noted that these items were originally documented in the PSL reports; however, additional information was provided for clarity in the Licensing Basis Evaluation for Unit 2 Equipment/Area ID "AWl3 - CTRL ROOM" and AR 1913922 has been added to the table to administratively document the simple analysis performed by the SWE to verify that the as found conditions still met their licensing basis function.
L-2013-321 Attachment Page 4 of 7 Unit 1 Equipment/Area Potentially Entered ID Adverse Seismic Licensing Basis Evaluation into Status Condition CAP Per EPRI NP7146s-SL RI, tested relay cabinets with similar properties of the Aux Relay Cabinet and PAP "A" Cabinet had fundamental frequencies ranging from 9.5 Hz to 11 Hz. The SSE horizontal spectral Approx. 3/16" gap acceleration at 9 Hz (lower-bound between Aux estimate) at the 61 ft elevation of the RAB AW22 -
Relay for 2% damping (in accordance with the AR RAB 62' CTRL Cabinet and PAP 1913922 Closed Rm "A" Cabinet.
U1 UFSAR) is approximately 0.45g.
Note #1 Determine whether Using a 1.6 modal shape factor for cantilever action and conservatively gap is adequate.
summing relative displacements, the maximum combined cabinet displacement is 0.17 in (=2* 1.6*0.45g*386.4 in/s^2/g) /
(2*pi*9 Hz)^2)). Therefore, the 3/16" gap is adequate.
Unit 2 Equipment/Area Potentially Adverse Licensing Basis Evaluation Entered Status ID Seismic Condition into CAP Per PSL Doc. 2998-20070, MCC front-to-back frequency is indicated as 6-7 Measured approx.
Hz. At 4% damping, horizontal 3/8" gap in front-to-spectral acceleration at 6 Hz (lower back direction (N-S) bound) at MP 3 of DGB is 0.85g.
AR 480V MCC 2B7 of MCC to concrete Upper-bound estimated displacement 1913922 Closed wall. Verify from for cantilevered structure with 1.6 Note #1 ISRS whether gap is modal participation factor is then sufficient.
(1.6*0.85g *386.4 in/sA2/g) / (2*pi*6 Hz)^2 = 0.37 in. Therefore, gap is adequate.
L-2013-321 Attachment Page 5 of 7 For a lower bound frequency estimate of 5 Hz (reasonable for floor-mounted distribution panel) at 4% damping on the 43' elevation of the RAB (M.P. 3),
Observed -5/8" gap the horizontal ISRS is 0.7g (STD-C-AR 125V DC BUS in front-to-back 04 2B direction to concrete 004). Upper-bound estimated 1913922 Closed wall to tohe North.
displacement for cantilevered structure Note #1 with 1.6 modal shape factor is then (I.6*0.70g *386.4 in/s^2/g) / (2*pi*5 Hz)^2 = 0.44 in. Therefore the 5/8" gap is adequate.
There is a gap of less than 1/32" between the Reactor Per STR-4698, SSE side-to-side Protection System maximum cabinet deflection is 0.144 cabinets and an a
p inches (based upon frequency of 7 Hz).
Point of contact with printer table is on the cabinet's
-34" above floor whereas north side. The gap RPS cabinet is -90" tall. Therefore, AR is in the side-to-side SSE deflection at point of interest is 1812128 direction of the AW13 - CTRL cabinet, which is 0.0544 in (=34"/90"
- 0.144). This Issued ROOM reasonably exceeds the 1/32" gap. AR1812128 was 10/11/12 Closed considered rigid, generated to evaluate the condition for Completed The table is operability concern, concluding (AR 11/14/12 anchored as well.
Section7C) that the condition did not Printer atop the table result in a Past Operability Concern.
Pis approatopthelyabl The gap between the RPS cabinet and from cabinet, which north printer cabinet was increased fromcabiet, hich to a minimum of 1/4/4.
is adequate spacing to preclude impact due to sliding.
Given squat transformer shape and motion along strong axis, a lower bound frequency of 10 Hz is Transformer reasonable. Per STD-C-004, the AW20 - RAB 43' PP201A / PP201 has spectral acceleration at El. 42.5 of the AR EAST A SWGR
-1/16" gap to bolt RAB (M.P. 3) at 4% damping is 0.35g.
1913922 Closed ROOM on concrete starter An upper bound estimate for 1
wall.
displacement with a modal shape factor of 1.6 for cantilever action is then:
1.6"0.35g'386.4 in/(s^2*g) / (2*pi* 10 Hz)A2 = 0.055". Therefore the 1/16" gap is adequate.
Note 1: These items were originally documented in the PSL reports (Ref.2) but were not entered into the Corrective Action Program (CAP) as part of the initial walkdowns. Simple analysis was performed by SWE to show no potential adverse seismic interaction. These items were conservatively included in report to document the SWE basis. AR 1913922 was issued to administratively document this issue on 10/21/13 and was completed 11/12/13.
L-2013-321 Attachment Page 6 of 7 NRC request for additional information:
(2) Conduct of the peer review process (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 performing 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."
PSL Response:
(a) The St. Lucie Nuclear Station Peer Review Team consisted of individuals from PSL Operations, Engineering, and Reliability Risk Assessment. As identified in Appendix F of the PSL reports (Ref. 2) the individual's roles in phases of preparation, performance and peer review of the seismic walkdowns were well defined. The peer review was performed consistent with Section 6-1 of the EPRI-TR-1025286 (Ref.3) guidance document and addresses the following specific activities:
Review of the selection of components for the Seismic Walkdown Equipment List Review of a sample of the checklists prepared for the Seismic Walkdowns & Walk-Bys Review of any licensing basis evaluations
- Review of the decisions for entering the potentially adverse conditions in to the plant's Corrective Action Program Review of the final submittal report (b) Appendix F of Florida Power & Light St. Lucie Nuclear Station submittal reports (Ref. 2) provided a detailed description of the conduct of the peer review process and experience/qualifications of the peer reviewers. The conduct of the peer review process used in these reports meet the EPRI guidance and included the name, task/activities and role of each team member in the peer review process.
The EPRI guidance does not directly address the expected level of independence of the peer review; however, as documented in Appendix F of each PSL report, peer review was provided for each activity of the report by assigned reviewer/reviewers that remained independent from the preparation of that report section. This method provided a comprehensive and meaningful review while also providing a reasonable level of independence.
L-2013-321 Attachment Page 7 of 7 References
- 1) NRC Letter, Request for Additional Information Associated with Near-Term Task Force Recommendation 2.3, Seismic Walkdowns, Dated November 1, 2013, Accession No. ML13304B418
- 2) Florida Power & Light (FPL) Letter L-2012-427, Dated November 27,2012, Response to NRC 10CFR50.54(f) Request for Information Regarding Near-Term Task Force Recommendation 2.3 Seismic
" St. Lucie Plant Unit 1, Seismic Walkdown Report 12Q4116-RPT-001, Rev.0
" St. Lucie Plant Unit 2, Seismic Walkdown Report 12Q4116-R-002, Rev. 0
- 3) EPRI-TR-1025286, Seismic Walkdown Guidance for Resolution of Fukushima Near-Term Task Force Recommendation 2.3: Seismic, Dated May 31, 2012