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{{Adams
#REDIRECT [[RNP-RA/14-0007, Response to NRC 10 CFR 50.54(f) Request for Additional Information Regarding Near-Term Task Force Recommendation 2.3, Flooding Update - Review of Available Physical Margin (APM) Assessments]]
| number = ML14037A104
| issue date = 01/30/2014
| title = H. B. Robinson Steam Electric Plant, Unit 2, Response to NRC 10 CFR 50.54(f) Request for Additional Information Regarding Near-Term Task Force Recommendation 2.3, Flooding Update - Review of Available Physical Margin (APM) Assessments
| author name = Gideon W R
| author affiliation = Duke Energy Carolinas, LLC, Duke Energy Progress, Inc
| addressee name =
| addressee affiliation = NRC/Document Control Desk, NRC/NRR
| docket = 05000261
| license number = DPR-023
| contact person =
| case reference number = RNP-RA/14-0007
| document type = Letter
| page count = 7
| project =
| stage = RAI
}}
 
=Text=
{{#Wiki_filter:W. R. GideonH. B. Robinson SteamElectric Plant Unit 2DUKE Site Vice President ENERGYDuke Energy Progress3581 West Entrance RoadPEROGRESS Hartsville, SC 295500:843 857 1701F: 843 857 1319 10 CFR 50.54(f)Serial: RNP-RA14-0007 JAN 3 0 2014ATTN: Document Control DeskU.S. Nuclear Regulatory Commission Washington, DC 20555H.B. ROBINSON STEAM ELECTRIC PLANT, UNIT NO. 2DOCKET NO. 50-261/RENEWED LICENSE NO. DPR-23
 
==Subject:==
 
Response to NRC 10 CFR 50.54(f)
Request for Additional Information Regarding Near-Term Task Force Recommendation 2.3, Flooding Update -Review ofAvailable Physical Margin (APM) 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-lchi 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, H. B. Robinson Steam Electric Plant, Unit No. 2 Responseto Recommendation 2.3, "Flooding Walkdown"of the Near- Term Task Force Review ofInsights from the Fukushima Dai-lchi Accident; dated November 26, 2012 (ADAMSAccession No. ML12340A067)
: 5. 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 50.54(f).
Enclosure 4 of that letter contains specific requested information associated with Near-Term Task Force Recommendation (NTTF) 2.3 for Flooding.
Nuclear Energy Institute (NEI) 12-07(Reference
: 2) was endorsed by NRC letter dated May 31, 2012 (Reference 3). By Reference 4,H. B. Robinson submitted the 180-day response to Reference 1 requiring the flooding walkdownreport addressing the items in Appendix D of NEI 12-07 (Reference 2).
U. S. Nuclear Regulatory Commission Serial: RNP-RA/14-0007 Page 2 of 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, 2013. The Duke Energy Progress response for H. B. Robinson Steam ElectricPlant, Unit No. 2 is enclosed.
This response supersedes the NEI FAQ 30 submittal that waspreviously discussed with the NRC Staff and scheduled for February 28, 2014.This letter contains no new Regulatory Commitments and no revision to existing Regulatory Commitments.
Should you have any questions regarding this submittal, please contact Mr. Richard Hightower, Manager Nuclear Regulatory
: Affairs, at (843) 857-1329.
I declare under penalty of perjury that the foregoing is true and correct.Executed on (('"I1Sincerely, W. R. GideonSite Vice President WRG/shc
 
==Enclosure:==
 
H. B. Robinson Steam Electric Plant, Unit No. 2 Response to the NRC Requestfor Additional Information (RAI) Regarding Available Physical Margin (APM)during Flooding Walkdowns cc: Mr. K. M. Ellis, NRC Senior Resident Inspector Mr. S. P. Lingam, NRC Project Manager, NRRMr. V. M. McCree, NRC Region II Administrator U. S. Nuclear Regulatory Commission Enclosure to Serial: RNP-RA/14-0007 Page 1 of 5Enclosure H. B. Robinson Steam Electric Plant, Unit No. 2Response to the NRC Request for Additional Information (RAI)Regarding Available Physical Margin (APM) during Flooding Walkdowns U. S. Nuclear Regulatory Commission Enclosure to Serial: RNP-RA/14-0007 Page 2 of 5Determination and Documentation of Available Physical Margin (APM)
 
==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 (NTTF) Recommendation 2.3report submittals.
APM is defined in Section 3.13 of NEI 12-07 and the process for obtaining and evaluating APM values is described in Section 5.8 of NEI 12-07. Consistent with NEI 12-07, a numerical 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 unsealed penetration in a barrier) such that theresulting flood can affect structures,
: systems, and components important to safety. Next, inaccordance with Section'5.8 of NEI 12-07, 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 doesnot require that a specific numerical threshold value for "small" APM be defined for each site,doing so establishes a consistent basis for determining what instances need to be entered intothe CAP. 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 thisRequest for Additional Information (RAI) is not to repeat the flooding walkdowns or perform anextensive revision of the walkdown record forms and other paperwork.
Instead the purpose is toverify or modify the process used to determine APM such that every site is aware of the marginat each of its flood protection features and take appropriate interim actions when the APM issmall and the consequences are significant.
Instances where numerical values for APM werenot determined, or where the basis for the APM was found to be questionable, should berectified by either the documentation of a specific value or an explanation of why a non-numerical value is appropriate.
U. S. Nuclear Regulatory Commission Enclosure to Serial: RNP-RAI14-0007 Page 3 of 5NRC RAI 1:Confirmation that the process for evaluating APM was reviewed; Response to RAI 1:Duke Energy Progress has completed a review of the flooding design basis walkdown processused at the H. B. Robinson Steam Electric Plant, Unit No. 2 to evaluate APMs.NRC RAI 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 2:The APM process used during flooding walkdowns was consistent with the guidance providedby NEI 12-07 and with the guidance provided in Reference 5 as it was applied to the currentlicensing basis flood protection features.
NRC RAI 3:If changes are necessary, a general description of any process changes to establish thisconsistency; Response to RAI 3:The determination and documentation of the APM. as performed during. the original floodingwalkdown effort followed the guidance provided in NEI 12-07 and in Reference 5, there were nochanges to the APM process.
U. S. Nuclear Regulatory Commission Enclosure to Serial: RNP-RA/14-0007 Page 4 of 5NRC RAI 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 12-07 Section 5.8 was followed.
a) 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 beencontrolled as a flooding seal, it was only necessary to determine that the sealconfiguration has been governed by the plant's design control process since installation.
In this case, the APM 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.
" Report the APM as "undetermined" and provide the CAP reference in the RAI response.
U. S. Nuclear Regulatory Commission Enclosure to Serial: RNP-RA/14-0007 Page 5 of 5Response to RAI 4:H. B. Robinson Steam Electric Plant, Unit No. 2 does not have credited seals in the currentlicensing basis, therefore, neither Approach A or B, as described above, were used to determine APM values for seals. As stated in the Duke Energy Progress Letter dated November 26, 2012(ADAMS Accession No. ML1 2340A067)(Reference 4), the credited flood protection
: feature, forH. B. Robinson, is the Tainter gates (including support components),
which are operated tomaintain the lake level at or below 222 ft. (Mean Sea Level) MSL.}}

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