ML14034A170
| ML14034A170 | |
| Person / Time | |
|---|---|
| Site: | Harris  |
| Issue date: | 01/29/2014 |
| From: | Kapopoulos E J Duke Energy Progress |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| HNP-14-007 | |
| Download: ML14034A170 (6) | |
Text
Ernest J. Kapopoulos, Jr.DUKE Vice President DUKER Harris Nuclear PlantEN ERGY 5413 Shearon Harris RdNew Hill NC 27562-9300 919-362-2502 10 CFR 50.54(f)January 29, 2014Serial: HNP-14-007 ATTN: Document Control DeskU.S. Nuclear Regulatory Commission Washington, DC 20555Duke Energy Progress, Inc. (Duke Energy)Shearon Harris Nuclear Power Plant, Unit 1Docket No. 50-400
Subject:
Response to Request for Additional Information Associated with Near-Term TaskForce Recommendation 2.3, Flooding Walkdowns, Regarding Available PhysicalMargin Assessments
References:
- 1. NRC Letter, Request for Information Pursuant to Title 10 of the Code of FederalRegulations 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, (Agencywide Documents Access and Management System (ADAMS) Accession No. ML12053A340)
- 2. NEI 12-07, Guidelines for Performing Verification Walkdown of Plant Flood Protection
- Features, Revision 0-A, dated May 20123. NRC Letter to Nuclear Energy Institute (NEI), Endorsement of Nuclear Energy Institute (NEI) 12-07, "Guidelines for Performing Verification Walkdowns of Plant Flood Protection Features,"
dated May 31, 2012, (ADAMS Accession No. ML12144A142)
- 4. Duke Energy Letter to NRC, Shearon Harris Nuclear Power Plant, Unit No. 1, Responseto Recommendation 2.3 Flooding Walkdown of the Near-Term Task Force Review ofInsights from the Fukushima Dai-ichi
- Accident, dated November 27, 20125. NRC letter, Request for Additional Information Associated with Near-Term Task ForceRecommendation 2.3, Flooding Walkdowns; dated December 23, 2013 (ADAMSAccession No. ML13325A891)
Ladies and Gentlemen:
On March 12, 2012, the Nuclear Regulatory Commission (NRC) staff issued Reference 1requesting information pursuant to Title 10 of the Code of Federal Regulations Part 50,Section 50.54(f).
Enclosure 4 of that letter contains specific requested information associated with Near-Term Task Force Recommendation 2.3 for Flooding.
Nuclear Energy Institute (NEI)12-07 (Reference
- 2) was endorsed by NRC letter dated May 31, 2012 (Reference 3). ByReference 4, Duke Energy submitted the 180-day response to Reference 1, for Shearon HarrisNuclear Power Plant, Unit 1, requiring the flooding walkdown report addressing the items inAppendix D of NEI 12-07 (Reference 2).
U.S. Nuclear Regulatory Commission HNP-14-007 Page 2Following the NRC staff's initial review of the walkdown
- reports, regulatory site audits wereconducted by the NRC staff at a sampling of plants. Based on the walkdown report reviews andsite audits, additional information was determined to be necessary to allow the NRC staff tocomplete its assessments.
By letter dated December 23, 2013 (Reference 5), the NRC requested additional information regarding the determination and documentation of available physical margin (APM) duringflooding walkdowns.
The NRC staff requested that a response be provided no later thanJanuary 31, 2014. The Duke Energy response for Shearon Harris Nuclear Power Plant, Unit 1,is enclosed.
This letter contains no new Regulatory Commitments and no revision to existing Regulatory Commitments.
Should you have any questions regarding this submittal, please contact Dave Corlett,Regulatory Affairs Manager, at (919) 362-3137.
I declare under penalty of perjury that the foregoing is true and correct.Executed on January 29, 2014.Sincerely, Ernest J. Kapopoulos, Jr.
Enclosure:
Shearon Harris Nuclear Power Plant, Unit 1, Response to the NRC Request forAdditional Information (RAI) Regarding Available Physical Margin DuringFlooding Walkdowns cc: Mr. J. D. Austin, NRC Sr. Resident Inspector, HNPMr. A. Hon, NRC Project Manager, HNPMr. V. M. McCree, NRC Regional Administrator, Region II U.S. Nuclear Regulatory Commission HNP-14-007, Enclosure Enclosure Shearon Harris Nuclear Power Plant, Unit IResponse to the NRC Request for Additional Information (RAI)Regarding Available Physical Margin During Flooding Walkdowns U.S. Nuclear Regulatory Commission HNP-14-007, Enclosure Page 1 of 3Determination and Documentation of Available Physical Margin
Background:
The NRC staff observed that several licensees did not consistently determine and/or documentavailable physical margin (APM) in a manner that met the expected interpretation of NEI 12-07during audits associated with review of the Near-Term Task Force Recommendation 2.3 reportsubmittals.
APM is defined in Section 3.13 of NEI 12-07 and the process for obtaining andevaluating APM values is described in Section 5.8 of NEI 12-07. Consistent with NEI 12-07, anumerical value for APM should be determined and documented for every applicable floodprotection feature (e.g., wall, penetration, berm, door, etc.). This would normally be a numerical value reflecting the difference between the licensing basis flood height at the location of thefeature and the point at which the function of the flood protection feature is compromised (e.g.,the top of a barrier or the height of the first unseated penetration in a barrier) such that theresulting flood can affect a structures,
- systems, and components important to safety. Next, inaccordance with Section 5.8 of NEI12-07, if the APM appears to be small and theconsequences of flooding appear to be significant, the licensee should enter the condition intothe corrective action program (CAP) and appropriate action be taken. While NEI 12-07 does notrequire that a specific numerical threshold value for "small" APM be defined for each site, doingso establishes a consistent basis for determining what instances need to be entered into theCAP. If a numerical APM value cannot be determined for any flood protection
- feature, thelicensee should perform an assessment of the ability of the barrier to withstand the licensing basis flood plus the contribution of the additional water corresponding to the pre-established small-margin threshold value. If the barrier can withstand this flood, the APM for the feature is"not small" and further evaluation in accordance with Section 5.8 of NEI 12-07 is not required.
Itis further noted that conclusions regarding "large" values of APM should be based onengineering evaluations or existing design documents.
Licensees should ensure that the process for APM determination and evaluation used duringtheir flooding walkdowns is consistent with the guidance in NEI 12-07. The intent of this requestfor additional information (RAI) is not to repeat the flooding walkdowns or perform an extensive revision of the walkdown record forms and other paperwork.
Instead the purpose is to verify ormodify the process used to determine APM such that every site is aware of the margin at eachof its flood protection features and take appropriate interim actions when the APM is small andthe consequences are significant.
Instances where numerical values for APM were notdetermined, or where the basis for the APM was found to be questionable, should be rectified by either the documentation of a specific value or an explanation of why a non-numerical valueis appropriate.
U.S. Nuclear Regulatory Commission HNP-14-007, Enclosure Page 2 of 3NRC RAI Item 1:Confirmation that the process for evaluating APM was reviewed; Response to RAI Item 1:Duke Energy has completed a review of the flooding design basis walkdown process used atShearon Harris Nuclear Power Plant to evaluate APMs.NRC RAI Item 2:Confirmation that the APM process is now or was always consistent with the guidance in NEI12-07 and discussed in this RAI;Response to RAI Item 2:The original walkdown effort followed the guidance provided in NEI 12-07. Although the originalwalkdown effort followed the guidance provided in NEI 12-07, APMs were not determined forthe seals associated with flood protection features.
Where the APM is undetermined, it hasbeen entered into the CAP (CR 663490).NRC RAI Item 3:If changes are necessary, a general description of any process changes to establish thisconsistency; Response to RAI Item 3:CAP entry CR 663490 addresses the following process changes consistent with the information provided in this RAI and in NEI 12-07:* Determine appropriate APM values for seals associated with flood protection features inaccordance with the guidance provided in NEI 12-07 and this RAI.* The development of small margin definitions to be used in place of engineering judgmentfor identifying small margin concerns.
- A review of APMs against the small margin definitions to validate reviews whichpreviously utilized engineering judgment to identify small margin concerns.
NRC RAI Item 4:As a result of the audits and subsequent interactions with industry during public meetings, NRCstaff recognized that evaluation of APM for seals (e.g., flood doors, penetrations, flood gates,etc.) was challenging for some licensees.
Generally, licensees were expected to use eitherApproach A or Approach B (described below) to determine the APM for seals:a) If seal pressure ratings were known, the seal ratings were used to determine APM(similar to example 2 in Section 3.13 of NEI 12-07). A numerical value for APM wasdocumented.
No further action was performed if the APM value was greater than thepre-established small-margin threshold value. If the APM value was small, anassessment of "significant consequences" was performed and the guidance in NEI 12-U.S. Nuclear Regulatory Commission HNP-14-007, Enclosure Page 3 of 307 Section 5.8 was followed.
b) If the seal pressure rating was not known, the APM for seals in a flood barrier isassumed to be greater than the pre-established small-margin threshold value if thefollowing conditions were met: (1) the APM for the barrier in which the seal is located isgreater than the small-margin threshold value and there is evidence that the seals weredesigned/procured, installed, and controlled as flooding seals in accordance with theflooding licensing basis. Note that in order to determine that the seal has been controlled as a flooding seal, it was only necessary to determine that the seal configuration hasbeen governed by the plant's design control process since installation.
In this case, theAPM for 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 part of theinitial walkdowns or as part of actions taken in response to this RAI. No additional actions arenecessary if either Approach A or B was used.If neither Approach A or B was used to determine the APM values for seals (either as part of thewalkdowns or as part of actions taken in response to this RAI), then perform the following twoactions:* Enter the condition into the CAP (note: it is acceptable to utilize a single CAP entry tocapture this issue for multiple seals). CAP disposition of "undetermined" APM values forseals should consider the guidance provided in NEI 12-07, Section 5.8. The CAPdisposition should confirm all seals can perform their intended safety function againstfloods up to the current licensing basis flood height. Disposition may occur as part of theIntegrated Assessment.
If an Integrated Assessment is not performed, determine whether there are significant consequences associated with exceeding the capacity ofthe seals and take interim action(s),
if necessary, via the CAP processes.
These actionsdo not need to be complete prior to the RAI response.
Response to RAI Item 4:Neither Approach A or B, as described above, were used to determine the APM values for thepenetration seals. Seals that were accessible were inspected as part of the original walkdowns for signs of degradation, and corrective actions were taken, when appropriate.
As part of theactions taken to address this RAI, the seals have been assigned an APM value of"undetermined" and have been entered into the CAP process (CR 663490) for further evaluation of their available physical margin.