RBG-47427, Update to Response to NRC 10 CFR 50.54(f) Request for Information Regarding Near-Term Task Force Recommendation 2.3, Flooding - Review of Available Physical Margin (APM) Assessments
| ML14042A161 | |
| Person / Time | |
|---|---|
| Site: | River Bend  |
| Issue date: | 01/27/2014 |
| From: | Evans T Entergy Operations |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| RBF1-14-0011, RBG-47427 | |
| Download: ML14042A161 (4) | |
Text
F Ente gy Entergy Operations, Inc.
River Bend Station 5485 U.S. Highway 61 N St. Francisville, LA 70775 RBG-47427 January 27, 2014 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555
Subject:
References:
Update to Response to NRC 10 CFR 50.54(f) Request for Information Regarding Near-Term Task Force Recommendation 2.3, Flooding - Review of Available Physical Margin (APM) Assessments River Bend Station - Unit 1 Docket No. 50-458 License No. NPF-47
- 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-lchi Accident; dated March 12, 2012, Accession No. ML12073A348.
- 2) NRC Letter to Nuclear Energy Institute, Endorsement of Nuclear Energy Institute (NEI) 12-07, "Guidelines for Performing Verification Walkdowns of Plant Flood Protection Features," dated May 31, 2012, Accession No. ML12144A142.
- 3) River Bend Station Letter RBG-47308, Flooding Walkdown Report - Entergy's Response to NRC Request for Information Pursuant to 10 CFR 50.54(f) Regarding the Flooding Aspects of Recommendation 2.3 of the Near-Term Task Force Review of Insights from the Fukushima Dai-ichi Accident River Bend Station - Unit 1, Docket No.
50-458, License No. NPF-47
- 4) NRC Letter, Request for Additional Information Associated with Near-Term Task Force Recommendation 2.3, Flooding Walkdowns; dated December 23, 2013, Accession No. ML13325A891 RBF1-14-0011
Dear Sir or Madam:
On March 12, 2012, the NRC staff issued Reference 1 requesting 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 2.3 for Flooding. Per Reference 2, the NRC endorsed Nuclear Energy Institute (NEI) 12-07, "Guidelines for Performing Verification Walkdowns of Plant Flood Protection Features," dated May 31, 2012. By Reference 3, River Bend Station submitted the final report in response to the request for information.
One of the requirements of NEI 12-07 is to identify the available physical margin (APM) associated with each applicable flood protection feature, determine if the margin provided is small, and evaluate any small margins that have potentially significant consequences through
RBG-47427 January 27, 2014 Page 2 of 2 the corrective action process. The results of this effort were to be maintained on site for future NRC audits.
Following the NRC staffs initial review of the walkdown reports, regulatory site audits were conducted at a sampling of plants. Based on the walkdown report reviews and site audits, the staff identified additional information necessary to allow them to complete its assessments.
Accordingly, by Reference 4 the NRC staff has issued a request for addition information (RAI).
The RAI questions and the River Bend Station responses are provided in Attachment 1.
Should you have any questions regarding this submittal, please contact Joseph Clark at 225-381-4177 Sincerely, Terry Ev s
Director-egulatory & Performance Improvement TAE/dhw Attachment cc:
U. S. Nuclear Regulatory Commission Region IV 1600 East Lamar Blvd.
Arlington, TX 76011-4511 NRC Sr. Resident Inspector P. 0. Box 1050 St. Francisville, LA 70775 Department of Environmental Quality Office of Environmental Compliance Radiological Emergency Planning and Response Section JiYoung Wiley P.O. Box 4312 Baton Rouge, LA 70821-4312 U.S. Nuclear Regulatory Commission Attn: Mr. Alan Wang Washington, DC 20555-0001 Public Document Room Public Utility Commission of Texas 1701 N. Congress Ave.
Austin, TX 78711-3326 RBG-47427 Update to Response to NRC 10 CFR 50.54(f) Request for Information Regarding Near-Term Task Force Recommendation 2.3, Flooding - Review of Available Physical Margin (APM)
Assessments RBG-47427 Page 1 of 1 RAI Number 1:
Confirmation that the process for evaluating APM was reviewed.
Response
River Bend Station has completed a review of the process for determining APM per NEI 12-07 as applied to River Bend Station.
RAI Number 2:
Confirmation that the APM process is now or was always consistent with the guidance in NEI 12-07 and discussed in this RAI.
Response: The original walkdown effort followed the guidance provided in NEI 12-07, including a definition for a small margin. Entergy developed corporate procedure EN-DC-170, "Fukushima Near Term Task Force Recommendation 2.3 Flooding Walkdown Procedure," to reflect the guidance provided in NEI 12-07. Per EN-DC-170, if margin was found to be "small" and the consequences of flooding appear to be significant, it was evaluated and corrected in the corrective action program (CAP). Entergy established APM "small margin" thresholds at 0'-6" for local intense precipitation (LIP) and 2'-6" for probable maximum (river) flood (PMF).
RAI Number 3:
If changes are necessary, a general description of any process changes to establish this consistency.
Response: As stated above, the original walkdown effort followed the guidance provided in NEI 12-07, including a definition for a small margin.
RAI Number 4: As a result of the audits and subsequent interactions with industry during public meetings, NRC staff 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 either approach "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 was documented. No further action was performed 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 12-07 Section 5.8 was followed.
b) If the seal pressure rating was not known, the APM for seals in a flood barrier is assumed to be greater than the pre-established small-margin threshold value if the following conditions were met: (1) the APM for the barrier in which the seal is located is greater than the small-margin threshold value and there is evidence that the seals were designed/procured, installed, and controlled as flooding seals in accordance with the flooding 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 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".
Response: River Bend Station used approach "a" to determine APM values for seals.