RA-14-011, 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
| ML14031A443 | |
| Person / Time | |
|---|---|
| Site: | Dresden, Peach Bottom, Byron, Three Mile Island, Braidwood, Limerick, Clinton, LaSalle  |
| Issue date: | 01/31/2014 |
| From: | Jim Barstow Exelon Generation Co |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| RA-14-011, RS-14-036, TMI-14-013 | |
| Download: ML14031A443 (7) | |
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RS-14-036 TMI-14-013 RA-14-011 January 31, 2014 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-0001 Braidwood Station, Units 1 and 2 Facility Operating License Nos. NPF-72 and NPF-77 NRC Docket Nos. STN 50-456 and STN 50-457 Byron Station, Units 1 and 2 Facility Operating License Nos. NPF-37 and NPF-66 NRC Docket Nos. STN 50-454 and STN 50-455 Clinton Power Station, Unit 1 Facility Operating License No. NPF-62 NRC Docket No. 50-461 Dresden Nuclear Power Station, Units 2 and 3 Renewed Facility Operating License Nos. DPR-19 and DPR-25 NRC Docket Nos. 50-237 and 50-249 LaSalle County Station, Units 1 and 2 Facility Operating License Nos. NPF-11 and NPF-18 NRC Docket Nos. 50-373 and 50-374 Limerick Generating Station, Units 1 and 2 Facility Operating License Nos. NPF-39 and NPF-85 NRC Docket Nos. 50-352 and 50-353 Peach Bottom Atomic Power Station, Units 2 and 3 Renewed Facility Operating License Nos. DPR-44 and DPR-56 NRC Docket Nos. 50-277 and 50-278 Three Mile Island Nuclear Station, Unit 1 Renewed Facility Operating License No. DPR-50 NRC Docket No. 50-289
U.S. Nuclear Regulatory Commission Supplemental Response to 50.54(f) Letter NTTF Recommendation 2.3: Flooding January 31, 2014 Page 2
Subject:
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
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-lchi Accident, dated March 12, 2012 (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 (3) Exelon Generation Company, LLC 180-day 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, dated November 27, 2012 (RS-12-160) (Braidwood Station, Units 1 and 2)
(4) Exelon Generation Company, LLC 180-day 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, dated November 27, 2012 (RS-12-162) (Byron Station, Units 1 and 2)
(5) Exelon Generation Company, LLC 180-day 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, dated November 27, 2012 (RS-12-166) (Clinton Power Station, Unit 1)
(6) Exelon Generation Company, LLC 180-day 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, dated November 27, 2012 (RS-12-168) (Dresden Nuclear Power Station, Units 2 and 3)
(7) Exelon Generation Company, LLC 180-day 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, dated November 27,2012 (RS-12-164) (LaSalle County Station, Units 1 and 2)
U.S. Nuclear Regulatory Commission Supplemental Response to 50.54(f) Letter NTTF Recommendation 2.3: Flooding January 31, 2014 Page 3 (8) Exelon Generation Company, LLC 180-day 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, dated November 19, 2012 (RS-12-172) (Limerick Generating Station, Units 1 and 2)
(9) Exelon Generation Company, LLC 180-day 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, dated November 19, 2012 (RS-12-174) (Peach Bottom Atomic Power Station, Units 2 and 3)
(1 0) Exelon Generation Company, LLC 180-day 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, dated November 19, 2012 (RS-12-176) (Three Mile Island Nuclear Station, Unit 1)
(11) NRC Letter, Request for Additional Information Associated with Near-Term Task force Recommendation 2.3, Flooding Walkdowns, dated December 23, 2013 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 References 3 through 10, Exelon Generation Company, LLC (EGC) submitted the final reports for the referenced EGC Stations 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 flood protection feature, determine if the margin provided is small, and evaluate any small margins that have potentially significant consequences through the corrective action process. The results of this effort were to be maintained on site for future NRC audits.
Following the NRC staff's 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 11, the NRC staff has issued a request for addition information (RAI). The RAI questions and the EGC responses are provided below.
U.S. Nuclear Regulatory Commission Supplemental Response to 50.54(f) Letter NTTF Recommendation 2.3: Flooding January 31, 2014 Page4 NRC RAI Number 1: Confirmation that the process for evaluating APM was reviewed.
Response: EGC has completed a review of the process used at the subject EGC Sites to evaluate APMs.
NRC 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 APM. Further clarification on the application of NEI 12-07 for APM, culminating with the issuance of this RAI, resulted in additional reviews for passive flood protection features, particularly seals. Additional reviews and documentation were completed to make the process consistent with the information provided in this RAI.
NRC 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 APM. However, EGG's understanding of the application of NEI 12-07 for APM resulted in some passive features, particularly seals, not receiving a numerical APM value. These items have now been addressed in accordance with the guidance provided in this RAJ.
NRC RAJ 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 8 (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 NE/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 NE/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 planrs design control process since installation. In this case, the APM for the seal could have been documented as "not small".
U.S. Nuclear Regulatory Commission Supplemental Response to 50.54(f) Letter NTTF Recommendation 2.3: Flooding January 31, 2014 Page 5 As part of the RAI response, state if either Approach A or Approach 8 was used as part of the initial walkdowns or as part of actions taken in response to this RAJ. No additional actions are necessary if either Approach A or 8 was used.
If neither Approach A or 8 was used to determine the APM values for seals (either as part of the walkdowns or as part of actions taken in response to this RAI), then perform the following two actions:
- Enter the condition into the CAP (note: it is acceptable to utilize a single CAP entry to capture this issue for multiple seals). CAP disposition of "undetermined" APM values for seals should consider the guidance provided in NE/12-07, Section 5.8.
The CAP disposition should confirm all seals can perform their intended safety function against floods up to the current licensing basis flood height. Disposition may occur as part of the Integrated Assessment. If an Integrated Assessment is not performed, determine whether there are significant consequences associated with exceeding the capacity of the seals and take interim action(s), if necessary, via the CAP processes. These actions do not need to be complete prior to the RAJ response.
Response: All seals were inspected as part of the original walkdowns for signs of degradation, and corrective actions were taken, if required. The approach taken to address APM for seals varied by site and is summarized below.
- Approach A- Limerick Generating Station had known pressure ratings for door seals that were used to determine APM. A numerical value for APM was documented and dispositioned according to NEI 12-07, Section 5.8.
- Approach B-At Peach Bottom Atomic Power Station, LaSalle County Station, Byron Station, Braidwood Station, Clinton Power Station, and Limerick Generating Station (below-grade seals only), the seal pressure ratings are assumed to be greater than the pre-established small-margin threshold value. There is evidence the seals were designed/procured, installed, and controlled as flooding seals in accordance with the flooding licensing basis. The seal configuration has been governed by the plant*s design control process since installation. Therefore, the APM for seals have been designated as nnot small. n
- For Three Mile Island Nuclear Station, Unit 1, all seals were inspected as part of the original walkdowns for signs of degradation, and corrective actions were taken, if required. As part of the actions taken to address this RAI, all passive protective features were reviewed and either an APM value was assigned (Approach A), the design control process governed the seal configuration to allow a conclusion that APM is nnot smaUU (Approach B), or the APM for the feature was designated as
~~undetermined." The CAP process was initiated to address any features with an 11 Undetermined 11 APM designation. (Reference Issue Report No. 1599328).
U.S. Nuclear Regulatory Commission Supplemental Response to 50.54(f) Letter NTTF Recommendation 2.3: Flooding January 31, 2014 Page 6
- Dresden Nuclear Power Station is licensed to permit river flooding into the plant and mitigate the effects to maintain safe shutdown conditions. Therefore, there are no passive barriers credited with protecting the plant from river flooding. Below-grade barriers, including concrete walls, floor, and seals, protect against groundwater ingress at a design basis level equal to ground level. Since groundwater cannot rise above ground surface, APM for these features is designated as .. not small. ..
This letter contains no new regulatory commitments and no revision to existing regulatory commitments.
If there are any questions regarding this submittal, please contact Ron Gaston at (630) 657-3359.
I declare under penalty of perjury that the foregoing is true and correct. Executed on the 31st day of January 2014.
Respectfully, Jame Barstow Director- Licensing & Regulatory Affairs Exelon Generation Company, LLC cc: Director, Office of Nuclear Reactor Regulation Regional Administrator- NRC Region I Regional Administrator- NRC Region Ill NRC Senior Resident Inspector- Braidwood Station NRC Senior Resident Inspector- Byron Station NRC Senior Resident Inspector - Clinton Power Station NRC Senior Resident Inspector- Dresden Nuclear Power Station NRC Senior Resident Inspector - LaSalle County Station NRC Senior Resident Inspector- Limerick Generating Station NRC Senior Resident Inspector- Peach Bottom Atomic Power Station NRC Senior Resident Inspector- Three Mile Island Nuclear Station, Unit 1 NRC Project Manager, NRR - Braidwood Station NRC Project Manager, NRR- Byron Station NRC Project Manager, NRR - Clinton Power Station NRC Project Manager, NRR - Dresden Nuclear Power Station NRC Project Manager, NRR - LaSalle County Station NRC Project Manager, NRR- Limerick Generating Station NRC Project Manager, NRR - Peach Bottom Atomic Power Station NRC Project Manager, NRR - Three Mile Island Nuclear Station, Unit 1 Ms. Jessica A. Kratchman, NRR/JLD/PMB, NRC Mr. Eric E. Bowman, NRR/DPR/PGCB, NRC or Ms. Eileen M. McKenna, NRO/DSRA/BPTS, NRC Illinois Emergency Management Agency - Division of Nuclear Safety
U.S. Nuclear Regulatory Commission Supplemental Response to 50.54(f) Letter NTTF Recommendation 2.3: Flooding January 31, 2014 Page 7 cc cont'd:
Director, Bureau of Radiation Protection - Pennsylvania Department of Environmental Resources Chairman, Board of County Commissioners of Dauphin County, PA Chairman, Board of Supervisors of Londonderry Township, PA S. T. Gray, State of Maryland R. R. Janati, Chief, Division of Nuclear Safety, Pennsylvania Department of Environmental Protection, Bureau of Radiation Protection