ML14031A146

Duane Arnold Energy Center Update to NextEra Energy Duane Arnold, Llc'S Response to NRC Request for Additional Information Associated with Near-Term Task Force Recommendations

ML14031A146
Person / Time
Site:	Duane Arnold
Issue date:	01/29/2014
From:	Anderson R L NextEra Energy Duane Arnold
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
Download: ML14031A146 (7)

Text

NExTeraENERGY4ARNOLDJanuary 29, 2014NG-14-0016 10 CFR 50.54(f)U. S. Nuclear Regulatory Commission ATTN: Document Control DeskWashington, DC 20555-0001 Duane Arnold Energy CenterDocket No. 50-331Renewed Op. License No. DPR-49Update to NextEra Enerqy Duane Arnold, LLC's Response To NRC Request forAdditional Information Associated with Near-Term Task Force Recommendation 2.3, Floodinq

-Review of Available Physical Marqin (APM) Assessments

References:

1) NRC Letter, "Request for Information Pursuant to Title 10 ofthe Code of Federal Regulations 50.54(f)

Regarding Recommendations 2.1, 2.3, and 9.3, of the Near-Term TaskForce Review of Insights from the Fukushima Dai-ichiAccident,"

dated March 12, 2012 (ML12073A348)

2) NRC Letter to Nuclear Energy Institute, Endorsement ofNuclear Energy Institute (NEI) 12-07, "Guidelines forPerforming Verification Walkdowns of Plant Flood Protection Features,"

dated May 31, 2012 (ML12144A142)

3) Letter, R. Anderson (NextEra Energy Duane Arnold, LLC) toNRC, "Response to NRC 10 CFR 50.54(f)

Request forInformation Regarding Near-Term Task ForceRecommendation 2.3, Flooding,"

NG-12-0461, datedNovember 27, 2012 (ML12342A004)

4) NRC Letter, "Request for Additional Information Associated with Near-Term Task Force Recommendation 2.3 FloodingWalkdowns,"

dated December 23, 2013 (ML13325A891)

On March 12, 2012, the Nuclear Regulatory Commission (NRC) issued Reference 1 requesting information on several topics including information associated withNear-Term Task Force Recommendation 2.3, Flooding.

Per Reference 2, theNRC endorsed Nuclear Energy Institute (NEI) 12-07, "Guidelines for Performing Verification Walkdowns of Plant Flood Protection Features."

In Reference 3,!NextEra Energy Duane Arnold, LLC, 3277 DAEC Road, Palo, IA 52324 Document Control DeskNG-14-0016 Page 2 of 2NextEra Energy Duane Arnold, LLC (hereafter NextEra Energy Duane Arnold)provided the requested information.

NEI 12-07 required licensees to identify the available physical margin (APM)associated with each applicable flood protection

feature, determine if the marginprovided is small, and evaluate any small margins that have potentially significant consequences through the corrective action process.

Following the NRC Staff'sinitial review of walkdown

reports, regulatory site audits were conducted at asampling of plants. Based on the walkdown report reviews and site audits, theStaff identified additional information, as documented in Reference 4, needed tocomplete its assessments.

The enclosure to this letter provides the information requested in Reference 4.This letter makes no new commitments or changes to existing commitments.

If you have any questions or require additional information, please contact KenPutnam at 319-851-7238.

I declare under penalty of perjury that the foregoing is true and correct.Executed on January 29, 2014N'hard L. Ander nVice President, Duane Arnold Energy CenterNextEra Energy Duane Arnold, LLCEnclosure Enclosure to NG-14-0016 Update to NextEra Energy Duane Arnold, LLC's Response To NRC Request forAdditional Information Associated with Near-Term Task Force Recommendation 2.3, Flooding

-Review of Available Physical Margin (APM) Assessments 3 pages follow Update to NextEra Energy Duane Arnold, LLC's Response To NRC Request forAdditional Information Associated with Near-Term Task Force Recommendation 2.3, Flooding

-Review of Available Physical Margin (APM) Assessments NRC Request 1:Provide confirmation that the process for evaluating APM was reviewed.

NextEra Energy Duane Arnold Response to Request 1:NextEra Energy Duane Arnold completed a review of the process used at Duane ArnoldEnergy Center to evaluate APMs.NRC Request 2:Provide confirmation that the APM process is now or was always consistent with theguidance in NEI 12-07 and discussed in this RAI.NextEra Energy Duane Arnold Response to Request 2:The original walkdown effort followed the guidance provided in NEI 12-07, including defining and documenting applicability of determined small margin issues. Additional actions were performed to ensure the process is consistent with the information in thisRAI.NRC Request 3:Provide, if changes are necessary, a general description of any process changes toestablish this consistency.

NextEra Energy Duane Arnold Response to Request 3:The NEI 12-07 walk down effort followed the guidance provided in NEI 12-07, including a definition for a small margin. However, a specific APM was not assigned to the sealsin below grade walls associated with flood protection features.

These items have beenaddressed in accordance with the guidance provided in this RAI, and entered into thecorrective action process for further action.NRC Request 4:As a result of the audits and subsequent interactions with industry during publicmeetings, NRC staff recognized that evaluation of APM for seals (e.g., flood doors,Page 1 of 3 penetrations, flood gates, etc.) was challenging for some licensees.

Generally, licensees were expected to use either Approach A or Approach B (described below) todetermine the APM for seals:a) If seal pressure ratings were known, the seal ratings were used todetermine APM (similar to example 2 in Section 3.13 of NEI 12-07). Anumerical value for APM was documented.

No further action wasperformed if the APM value was greater than the pre-established small-margin threshold value. If the APM value was small, an assessment of"significant consequences" was performed and the guidance in NEI 12-07Section 5.8 was followed.

b) If the seal pressure rating was not known, the APM for seals in a floodbarrier is assumed to be greater than the pre-established small-margin threshold value if the following conditions were met: (1) the APM for thebarrier in which the seal is located is greater than the small-margin threshold value and there is evidence that the seals weredesigned/procured, installed, and controlled as flooding seals inaccordance with the flooding licensing basis. Note that in order todetermine that the seal has been controlled as a flooding seal, it was onlynecessary to determine that the seal configuration has been governed bythe plant's design control process since installation.

In this case, the APMfor the seal could have been documented as "not small".As part of the RAI response, state if either Approach A or Approach B was used as partof the initial walkdowns or as part of actions taken in response to this RAI. No additional actions are necessary if either Approach A or B was used.If neither Approach A or B was used to determine the APM values for seals (either aspart of the walkdowns or as part of actions taken in response to this RAI), then performthe following two actions:* Enter the condition into the CAP (note: it is acceptable to utilize a single CAPentry to capture this issue for multiple seals). CAP disposition of "undetermined" APM values for seals should consider the guidance provided in NEI 12-07,Section 5.8. The CAP disposition should confirm all seals can perform theirintended safety function against floods up to the current licensing basis floodheight. Disposition may occur as part of the Integrated Assessment.

If anIntegrated Assessment is not performed, determine whether there are significant consequences associated with exceeding the capacity of the seals and takeinterim action(s),

if necessary, via the CAP processes.

These actions do notneed to be complete prior to the RAI response.

• Report the APM as "undetermined" and provide the CAP reference in the RAIresponse.

Page 2 of 3 NextEra Enercv Duane Arnold Response to Request 4:Neither Approach A or B, as described above, were used to determine the APM valuesfor seals in below grade walls/floors.

Seals in below grade walls/floors were inspected as part of the original walkdowns for signs of degradation, and corrective actions wereinitiated, if required.

As part of the actions taken to address this RAI, the seals in belowgrade walls/floors have been assigned an APM value of "undetermined" and have beenentered into the CAP process (CR1934141) for further evaluation of their available physical margin. Implementation of interim actions will be pursued, if necessary.

Page 3 of 3 CARBON COPY LIST FOR NG-14-0016 January 29, 2014Regional Administrator, USNRC, Region IIIResident Inspector, USNRC, Duane Arnold Energy CenterProject Manager, USNRC, Duane Arnold Energy Center

Subject:

Update to NextEra Energy Duane Arnold, LLC's Response To NRC Requestfor Additional Information Associated with Near-Term Task ForceRecommendation 2.3, Flooding

-Review of Available Physical Margin(APM) Assessments