ML20236E329
| ML20236E329 | |
| Person / Time | |
|---|---|
| Site: | Sequoyah  |
| Issue date: | 01/06/1987 |
| From: | TENNESSEE VALLEY AUTHORITY |
| To: | |
| Shared Package | |
| ML20236E191 | List: |
| References | |
| 215.1(B), 215.1(B)-R, 215.1(B)-R00, NUDOCS 8710290178 | |
| Download: ML20236E329 (8) | |
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'TVA EMPLOYEE CONCERNS REPORT NUMBER: -215.1(B):
SPECIAL PROGRAM REPORT TYPE:
.SEQUOYAH ELEENT REVISION NUMBER:: 0
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TITLE:-
CIVIL / STRUCTURAL-DESIGN.
Seismic.CriteriaL PAGE 1 0F 8-i
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' REASON FOR REVISION:
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SIGNATURE DATE SIGNATURE DATE APPROVED BY:
ECSP MANAGER DATE MANAGER OF NUCLEAR POWER DATE CONCURRENCE (FINAL REPORT ONLY) 1
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~TVA EMPLOYEE CONCERNS REPORT NUMBER: -215.l(B)
SPECIAL' PROGRAM REVISION NUMBER:
0-
-=
PAGE 2 0F 8 l.
CHARACTERIZATION OF ISSUES:.
Concerns:
Issues:
00-85-005-009 a.
SQN is on an earthquake fault that.
"Sequoyah Nuclear Plant is runs from Chattanooga to Knoxville.
sited on an earthquake fault that runs from around b.
Plant structures could f ail in an Chattanooga to north of.
Knoxville.
If there were an earthquake power plant structures could fail."
0W-85-007-007 (WBN)'
- Identical concern for WBN.
a 2.-
HAS ISSUE BEEN IDENTIFIED IN ANOTHER SYSTEMATIC ANALYSIS? YES NO X Identified by None Date Not Applicable Documentation Identifiers: Not Applicable 3..
DOCUMENT NOS., TAG NOS., LOCATIONS OR OTHER SPECIFIC DESCRIPTIVE
. IDENTIFICATIONS STATED IN ELEMENT:
No numbers are stated. The concern is generic to the basic design of SQN.
4.
INTERVIEW FILES REVIEWED:
Files 0W-85-007 and 00-85-005 were reviewed by the evaluation team (10/31/86). The files contain the K-forms, employee concern assignment requests, Forms G-A, generic applicability determination change forms, end TVA' Nuclear Safety-Review Staff (NSRS) reports.
NSRS report I-86-110-SQN is specifically applicable to concern 00-85-005-009. No additional unreviewed information for SQN regarding these concerns was identified.
0527D (12/23/86)
,o TVA EMPLOYEE CONCERNS REPORT NUMBER:' 215.l(B).
.SPECIAL PROGRAM 7:,
PAGE 3 0F 8 w-5.-
0OCUMENTS REVIEWED RELATED TO THE ELEMENT:
l See Appendix A.-
6.-
WHAT-REGULATIONS, LICENSIN'G COMMITMENTS, DESIGN REQUIREMENTS OR OTHER APPLY OR CONTROL IN THIS AREA?
See Appendix A.
7.-
LIST REQUESTS FOR INFORMATION, MEETINGS, TELEPHONE CALLS, AND OTHER DISCUSSIONS RELATED TO ELEMENT.
l
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-See Appendix A.
i 8.
EVALUATION PROCESS:
a.
Reviewed Section 2.5 of both the FSAR and SER.
I b.
Compared geological settings of SQN and WBN for which a detailed review has been completed and sought any significant differences.
c.
Reviewed TVA NSRS report I-86-110-SQN.
9.
DISCUSSION, FINDINGS, AND CONCLUSIONS:
Ch ronology:
11/15/85:
TVA receives employee concern l
03/03/86:
NSRS Report No. I-86-110-SQN prepared i
Discussion:
The expressed concern was evaluated in the following manner.
First, the FSAR Update for the Sequoyah Nuclear Plant was reviewed. Second, Section 2.5 of the Safety Evaluation Report (SER) for the site, prepared by the NRC in March 1979, was reviewed as well as supplements to the SER through December 1982.
'05270(12/23/86)
TVA EMPLOYEE CONCERNS REPORT NUMBER:
21' 5. l(B )
SPECIAL PROGRAM REVISION NUMBER: 0 PAGE 4 0F 8 3;
The goals of this review were to determine (1) if Sequoyah is located on an earthquake fault, (2) if an earthquake fault runs from Chattanooga to north of Knoxville, and (3) if this tectonic feature is capable of an earthquake of sufficient magnitude to seriously damage the structural integrity of the Sequoyah Plant.
The Sequoyah site is located in the Valley and Ridge Physiographic Province of the Appalachian Highlands.
This province is characterized by highly folded and faulted northeast-trending
_ sedimentary rocks of Paleozoic age (250 to 580 million years old).
Valleys have formed along the softer rocks such as shales and soluble limestones, and the ridges are formed by harder, more resistant sandstones, limestones, and dolomites.
The Sequoyah site is underlain by several thrust faults, one of which is the Kingston fault.
It is a major, extensive fault which is exposed at ground surface approximately 1 mile northwest of the site and underlies the site at a depth of several thousand feet.
The northeast end of the Kingston fault is in Anderson County, Tennessee, and the fault extends to the southwest for 175 miles or so through Tennessee and beyond.
Considering that the extent of the Kingston fault is approximately as stated in the concern, and that essentially the same terminology is used to describe the " earthquake fault," it is surmised that the individual may be concerned that the Kingston fault is an
" earthquake fault."
If so, the evidence clearly shows that the Kingston fault and the other thrust faults of similar age and origin under the site have for decades been considered to be inactive faults, and they are still considered to be inactive by geologists and seismologists who are most knowledgeable about them.
The evaluation team is not aware of any evidence, or even hypothesis, that the Kingston fault or the other thrust faults that
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developed near the end of the Paleozoic are capable faults. On the contrary, the available evidence indicates they are not.
The thrust faults in the region around the Sequoyah site typically dip to the southeast at and near ground surface and flatten with depth. At the present, it is generally accepted that these thrust faults merge at a depth of about 3 miles with a nearly flat regional sole fault, or decollement, or detachment fault. Because there has been relatively recent speculation in the literature that the Charleston earthquake might have been related to the j
decollement structures, perhaps the individual is concerned that the decollement under the Sequoyah site might be an " earthquake fault."
05?70 (12/23/86)
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TVA EMPLOYEE CONCERNS REPORT NUMBER: 215.l(B) l SPECIAL PROGRAM REVISION NUMBER: 0 PAGE fs0F 8 i
However, evidence has not been established that the Charleston earthquake was even related to a decollement-type structure, nor that the Appalachian decollement extends as far as Charleston.
There is considerable evidence that it does not.
Hence, there is no evidence to support an inference that the decollement under the sites is in any way related to the Charleston earthquake or that the decollement under the plant might be an " earthquake fault."
Historically earthquakes in the Appalachians, which have been accurately located as to their hypocentral depth, typically occur below a depth;of 7 km (4.3 miles), which is several kilometers below the thrust faults and the decollement zone.
Consequently these earthquakes do not furnish any evidence for the existence of k
"an earthquake fault that runs from around Chattanooga to north of Knoxville," and underlies the Sequoyah site. As stated in the FSAR and the literature, thrust faults exist under the site but the evidence indicates that they are not capable faults, or " earthquake faults."
On the basis of this review, the evaluation team noted that:
a.
The Sequoyah site is located in an area with several thrust faults which trend northeast-southwest. None of these thrust b
faults are considered earthquake faults (i.e., faults capable of producing significant earthquakes that could adversely affect the Sequoyah plant).
b.
A single, continuous earthquake fault from Chattanooga to north of Knoxville does not exist within this region. More correctly, the pattern of faulting consists of several, parallel thrust faults which typically dip southeast at and near ground surface and flatten with depth.
They are oriented in a northeast-southwest direction. As noted above, none of these features are considered earthquake faults.
c.
TVA investigations of the geology, seismology, and geotechnical engineering conditions as presented in FSAR Update Section 2.5 through Amendment 3 have thoroughly examined the subject and have concluded that the 0.18 g Safe Shutdown Earthquake (SSE) seismic response spectra are adequate as the basis for the seismic design of Sequoyah to ensure a safe shutdown of the plant.
In addition, TVA investigated the existing design employing a 0.22 g site-specific seismic response spectra which uses the 84th percentile of 13 actual earthquake recordings.
This investigation determined that all Category I structures are afequate for seismic loading associated with this site specific spectra (App. A, 5.a).
i 05270 (12/23/86)
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TVA EMPLOYEE CONCERNS REPORT NUMBER: 215.l(B)
SPECIAL PROGRAM REVISION NUMBER: 0 l}
PAGE 6 0F 8 d.
In the SER through Supplement 6, the NRC has concluded that:
o The present design basis for SQN is adequate to l
t withstand the effects of earthquakes without loss ~of capability to perform the required safety functions, o
The seismic Category I structures are acceptable for.
. seismic. loadings calculated on the basis of the 84th percentile site-specific response spectra when used.in conjunction with the damping values reconnended by Regulatory Guide 1.61, " Damping Values for S-bismic-
- Design of Nuclear Power Plants." The structures also meet the. objective of Standard Review Plan-(SRP)Section3.7.
Concern 00-85-005-009 was investigated by TVA NSRS Report I-86-110-SQN (03/03/86). Based upon review of the FSAR, SER,_and applicable licensing requirements and commitments, that report.
concluded that SQN is not located on a earthquake fault, and that the seismic analyses' performed by TVA, and accepted by the NRC, will permit safe plant operations and ensure adequate design margins _for the safe shutdown of the plant.
Findings:-
The alphabetic identifiers below correspond to the list of issues in Section 1.
.The Sequoyah Nuclear Plant is located in an area with several a.
thrust faults which trend northeast-southwest.
None of these thrust faults are considered earthquake faults (i.e., faults capable of producing significant earthquakes which could adversely affect the Sequoyah Nuclear Plant).
b.
TVA investigations of the geology, seismology, and geotechnical engineering conditions as presented in FSAR Update, Section 2.5 through Amendment 3 have thoroughly f-examined the subject and have concluded that the seismic response spectra used in the design for Sequoyah are adequate to ensure safe shutdown of the plant.
In the SER through Supplement 6, the NRC has concluded that:
o The present design basis for SQN is adequate to withstand the effects of earthquakes without loss of capability to perform the required safety functions.
05270(12/23/86)
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'4 TVA EMPLOYEE CONCERNS REPORT NUMBER:
215.l(B)
SPECIAL PROGRAM REVISION NUMBER:
0
,m PAGE 7 0F 8 l%.iN o
The seismic Category I structures are acceptable for seismic loadings calculated.on the basis of the 84th percentile site-specific response spectra and meet the objective of SRP Section 3.7.
==
Conclusion:==
.After review of the documents, the evaluation team concludes that
.the available data, including TVA and NRC reviews,-do.not support the concern that Sequoyah Nuclear Power Plant is sited on an earthquake fault, nor that a resultant earthquake would seriously damage the plant's structural integrity.
Therefore, the concern is not valid and does not require any further action.
- 10. CORRECTIVE ACTION:
No corrective action is required.
m W
05270(12/23[86)
REPORT NUMBER: 215.1(B)
TVA EWLOYEE CONCERNS SPECIAL PROGRAM REVISION NUMBER:. 0 PAGE 8 0F 8 i
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- g. 'r APPENDIX A 5.
DOCUMENTS REVIEWED RELATED TO THE ELEMENT:
a.
Nuclear Safety Review Staff (NSRS) Report No. I-86-110-SQN (03/03/86) b.
Letter from TVA's L. M. Mills, Manager of Nuclear Regulation and Safety, to NRC's A. Schwencer, Chief, Licensing Branch No. 2,
Subject:
" Seismic Margin Program Plan," [A27 810505 028}f (05/05/81) c.
SNP FSAR Update through Amendment 3 Section 2.5, " Geology and Seismology" Section 3.1, "Conformance with NRC General Design Criteria"'
Section 3.7, " Seismic Design" d..
NRC Safeth Evaluation Report (SER), NUREG-0011, issued 03/79, and including Supplements 1 through 6 (12/82) 6.
WHAT REGULATIONS, LICENSING COMMITMENTS, DESIGN REQUIREMENTS OR OTHER APPLY OR CONTROL IN THIS AREA?
a.
SNP FSAR Update through Amendment 3 Section 2.5, " Geology and Seismology" Section 3.1, "Conformance with NRC General Design Criteria" Section 3.7, " Seismic Design" b.
NRC Safety Evaluation Report (SER), NUREG-0011, issued 03/79, and including Supplements 1 through 6 (12/82) 7.
LIST REQUESTS FOR INFORMATION, MEETINGS, TELEPHONE _ CALLS, AND OTHER DISCUSSIONS RELATED TO ELEMENT.
RFI-SQN#690(11/05/86) 05270(12/23/86)
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