ML14167A069
| ML14167A069 | |
| Person / Time | |
|---|---|
| Site: | Seabrook  |
| Issue date: | 07/10/2014 |
| From: | Satorius M NRC/EDO |
| To: | Mcmilleon J Amesbury, MA |
| Erickson A, 415-1933 | |
| Shared Package | |
| ML14149A523 | List: |
| References | |
| LTR-14-0299-1, TAC MF4208 | |
| Download: ML14167A069 (4) | |
Text
July 10, 2014 Joseph W. McMilleon, Council President District 5 City Hall, Office of the City Clerk 62 Friend Street Amesbury, MA 01913
Dear Mr. McMilleon:
On behalf of the Nuclear Regulatory Commission (NRC), I am responding to your letter dated May 13, 2014, to Chairman Allison Macfarlane, expressing your concerns regarding the concrete degradation due to alkali-silica reaction (ASR) at the Seabrook Station (Seabrook) and requesting that the NRC staff continue to make public safety the top priority in its decisions with regard to the Seabrook plant.
The NRC staff recognizes that the ASR issue is complex and challenging because the onset, progression, and impact of ASR on nuclear power plant structures is still under investigation.
Accordingly, using our Reactor Oversight Process, we continue to carefully and deliberately monitor, assess, and inspect NextEra Energy Seabrook, LLCs (NextEras) ongoing efforts to address the long-term resolution of the Seabrook ASR issue. In the interim, NextEra conducted analysis, using bounding ASR-affected concrete properties derived from research data, to demonstrate that the Seabrook structures remain operable under design basis loads, which includes a site-specific design basis earthquake. The NRC staff reviewed NextEras analysis and documented its evaluation in NRC Inspection Report No. 05000443/2012009 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML12338A283). Our independent inspections and assessments to date have determined that the ASR-affected structures remain capable of performing their intended safety functions with margin from initial design and construction. Based on the slow and localized progression of ASR expansion, the operability evaluations, coupled with ongoing monitoring, provide reasonable assurance of continued safety.
With respect to your concerns regarding the licensees large-scale testing program, the NRC staff understands that this is a research effort, which is intended to quantify, in a bounding manner, the effect of different levels of ASR severity on the structural performance of ASR-affected reinforced concrete structures. This includes levels of ASR severity beyond those observed at Seabrook. While NextEras ASR monitoring program criteria are currently based on combined cracking index and crack width values obtained from several sources of published ASR research, NextEra has indicated that the results of the large-scale testing, with respect to its license renewal application, will seek to confirm that the parameters being monitored and the acceptance criteria used are appropriate and adequate to manage the effects of ASR.
The NRC staff did not rely on the results of the large-scale testing conducted by NextEra to conclude that the structures affected by ASR remain capable of performing their safety function.
As mentioned before, the basis for that conclusion is documented in NRC Inspection Report No.
05000443/2012009. Should NextEra elect to use the test results as the final resolution, the
testing methodology and results will be subject to an NRC review pursuant to the applicable regulatory processes described in Title 10 of the Code of Federal Regulations (10 CFR) Section 50.59 and/or 50.90. The concerns expressed by the Union of Concerned Scientists to the Commission and mentioned in your letter were received by the NRC staff, by letter dated November 4, 2013 (ADAMS Accession No. ML13309B606). The NRC staff reviewed the concerns and provided a response to the specific comments in a letter dated December 6, 2013 (ADAMS Accession No. ML13340A405). A copy of the response letter is enclosed for your information.
I would also like to address your concern regarding the 2012 earthquake, which occurred 60 miles from Seabrook, and whether the concrete affected by ASR would maintain its structural integrity if the earthquake had been stronger or closer to the site. The NRC notes that the plant has been conservatively designed to withstand the effects of stronger site-specific earthquakes with a maximum vibratory ground motion of 0.25 times gravity, based on appropriate consideration of the most severe geological and seismic historical evidence for the site and surrounding area. As documented in NRC Inspection Report No. 05000443/2012009, the inspection team concluded that NextEras interim structural assessment was appropriate to conclude that the seismic response of the ASR-affected structures at Seabrook have not been significantly impacted by the current state of ASR.
The licensee is engaged in further technical investigations and evaluations to address the long-term resolution of the ASR concrete degradation issue at the site, which the NRC staff continues to monitor closely. At this time, we have no immediate safety concern. Additionally, no regulatory decision has been made on NextEras license renewal application for Seabrook.
Please be assured that the agency will not hesitate to take any actions necessary and appropriate to adequately protect public health and safety.
I hope this information is useful to you. Please feel free to contact Mr. Michael Marshall, Branch Chief, at 301-415-2871 or Mrs. Alice Erickson, Structural Engineer, at 301-415-1933 should you have any further questions or comments to share with us.
Sincerely,
/RA/
Mark A. Satorius Executive Director for Operations
Enclosure:
As stated
testing methodology and results will be subject to an NRC review pursuant to the applicable regulatory processes described in Title 10 of the Code of Federal Regulations (10 CFR) Section 50.59 and/or 50.90. The concerns expressed by the Union of Concerned Scientists to the Commission and mentioned in your letter were received by the NRC staff, by letter dated November 4, 2013 (ADAMS Accession No. ML13309B606). The NRC staff reviewed the concerns and provided a response to the specific comments in a letter dated December 6, 2013 (ADAMS Accession No. ML13340A405). A copy of the response letter is enclosed for your information.
I would also like to address your concern regarding the 2012 earthquake, which occurred 60 miles from Seabrook, and whether the concrete affected by ASR would maintain its structural integrity if the earthquake had been stronger or closer to the site. The NRC notes that the plant has been conservatively designed to withstand the effects of stronger site-specific earthquakes with a maximum vibratory ground motion of 0.25 times gravity, based on appropriate consideration of the most severe geological and seismic historical evidence for the site and surrounding area. As documented in NRC Inspection Report No. 05000443/2012009, the inspection team concluded that NextEras interim structural assessment was appropriate to conclude that the seismic response of the ASR-affected structures at Seabrook have not been significantly impacted by the current state of ASR.
The licensee is engaged in further technical investigations and evaluations to address the long-term resolution of the ASR concrete degradation issue at the site, which the NRC staff continues to monitor closely. At this time, we have no immediate safety concern. Additionally, no regulatory decision has been made on NextEras license renewal application for Seabrook.
Please be assured that the agency will not hesitate to take any actions necessary and appropriate to adequately protect public health and safety.
I hope this information is useful to you. Please feel free to contact Mr. Michael Marshall, Branch Chief, at 301-415-2871 or Mrs. Alice Erickson, Structural Engineer, at 301-415-1933 should you have any further questions or comments to share with us.
Sincerely,
/RA/
Mark A. Satorius Executive Director for Operations
Enclosure:
As stated DISTRIBUTION: LTR-14-0299-1 See next page ADAMS Accession Nos.: ML14149A523 (PKG) ML14149A522 (incoming) ML14167A069 (Response)
- concurred via email OFFICE LA:RPB2:DLR*
PM:RASB:DLR:
PM:RPB1:DLR*
BC:DRS:RG1*
NAME IKing AErickson RPlasse MGray (NMcNamara for)
DATE 6/17/14 6/18/14 6/18/14 6/19/14 OFFICE NRR:DORL:BC NRR:DLR:BC DD:DLR:
Tech Editor*
NAME MKhanna MMarshall SWeeraklody JDougherty DATE 6/19/14 6/18/14 6/19/14 6/19/14 OFFICE D:NRR EDO NAME ELeeds (DDorman for)
MSatorius DATE:
6/20/14 7/10 /14 OFFICE RECORD COPY
Letter to J. McMilleon from M. Satorius dated July XX, 2014 DISTRIBUTION: LTR-14-0299-1 PUBLIC RidsNrrDlr Resource RidsNrrMailCenter Resource RidsRgn1MailCenter Resource RidsOgcMailCenter Resource RidsEdoMailCenter Resource RidsNsirMailCenter Resource NMcNamara, DLR MGray, RGN1 MKhanna, DORL J. Lamb, DORL