ML20153A932
| ML20153A932 | |
| Person / Time | |
|---|---|
| Site: | Perry  |
| Issue date: | 06/22/1988 |
| From: | Murley T Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20150C727 | List: |
| References | |
| 2.206, NUDOCS 8807120662 | |
| Download: ML20153A932 (37) | |
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7590-01 UNITED STATES NUCLEAR REGULATORY COMMISSION DOCKET NOS. 50-440 AND 50-441 CLEVELAND ELECTRIC ILLUMINATING COMPANY, ET AL.
PERRY NUCLEAR POWER PLANT, UNIT N05. 1 AND 2 ISSUANCE OF DIRECT'OR'S DECISION UNDER 10 CFR 2.206 Notice is hereby given that the Director, Office of Nuclear Reactor Regulation, has issued a Director's Decision concerning a Petition dated January 22, 1988, filed by Susan L. Hiatt on behalf of Ohio Citizens for Responsible Energy, Inc. (Petitioner). The Petitioner requested that the Nuclear Regulatory Commission (NRC) grant a variety of relief, including suspension of the operating license for the Perry Nuclear Power Plant, Unit l
l 1, and suspension of the construction permit for the Perry Nuclear Power Plant, Unit 2. The Petition alleged various seismic inadequacias in the Perry Nuclear Power Plant design, specifically:
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- 1. The earthquake of January 31, 1986, at Chardon, Ohio and the historic seismicity near the Perry Nuclear Power Plant can be associated with a iectonic structure (fault) that has been revealed by magnetic data.
- 2. This tectonic structure is capable of an earthquake with a magnitude of 6.5 or greater.
- 3. Thepresentsafe-shutdownearthquake(magnitudeof5.3 0.5) for the Perry facility does not provide the margin of safety required.
8807120662 880622 PDR ADOCK 05000440 G PDR l
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On the basis of these alleged inadequacies, Petitioner claimed that the Perry facility did not comply with the Comission's requirements related to seismic design.
On March 2,1988, the Director of the Office of Nuclear Reactor Regulation acknowledged receipt of the Petition and notified the Petitioner that this matter would be considered pursuant to 10 CFR 2.206.
The Director has determined that the Petitioner's request should be denied. The reasons for the denial are set forth in the "Director's Decision Pursuant to 10 CFR 2.206" (DD-88-10 ), which is available for inspection and copying in the Comission's Public Document Room,1717 H Street, N.W., Washington, D.C. 20555 and at the local public document room for the Perry Nuclear Power Plant at the Perry Public Library, 3753 Main Street, Perry, Ohio 44081.
A copy of the decision will be filed with the Secretary of the Comission for the Comission's review in accordance with 10 CFR 2.206(c).
As provided in 10 CFR 2.206(c), the decision will become the final action of the Comission 25 days after issuance unless the Comission on its own motion institutes review of the decision within that time.
FOR THE NUCLEAR REGULATORY COMMISSION f
Thomas E. Murley, Director Office of Nuclear Reactor Regulation Dated at Rockville, Maryland this 22nd day of June 1988
/ [og UNITED STATES
! n NUCLEAR REGULATORY COMMISSION 5 <E WASHING TON, D. C.' 20555
%,,,,, June 22, 1988 Docket Nos. 50-440 and 50-441 (10 CFR Section 2.206)
Ms. Susan L. Hiatt Ohio Citizens for Responsible Energy, Inc. .
8275 Munson Road Mentor, Ohio 44060
Dear Ms. Hiatt:
This letter responds to the "Petition for immediate Action to Relieve Undue Risk Posed by the Inadequate Seismic Design of the Perry Nuclear Power Plant" filed by you on behalf of the Ohio Citizens for Responsible Energy.
Inc. (Petitioner) on January 22, 1988 pursuant to 10 CFR 2.206. The Petition made the following allegations regarding the seismic design of the Perry Nuclear Power Plant (PNPP) of the Cleveland El ctric Illuminating Corpany et al. (Licensees):
- 1. The earthquake of January 31, 1986 at Chardon, Ohio and the historic seismicity near the PNPP can be associated with a tactonic structure (fault) that has been revealed by magnetic data.
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- 2. This tectonic structure is capable of an earthquake with a magnitude of l
6.5 or greater.
t 3. The present safe-shutdown earthquake (SSE) of magnitude of 5.3 t 0.5 l
for the PNPP does not provide an adequate margin of safety.
Based on these allegations, the Petition concluded that the PNPP does not comply with the Cemission's regulations regarding seismic design required t
by 10 CFR Part 50, Appendix A, General Design Criterion 2, and 10 CFR Part 100, Appendix A, Parts IV, V, and VI.
The Petition requested an imediate suspension of the operating license (OL) for PNPP Unit 1 and the construction pennit (CP) for PNPP Unit 2. It i further requested that additional geologic and geophysical studies be l
conducted, and appropriate corrective actions considered, by the Licensees and that an adjudicatory hearing be held to evaluate the effectiveness of those corrective actions.
On March 2,1988, I sent you a letter acknowledging receipt of the Petition and declined to take any immediate action for the reasons stated in that 1
1 t
Ms. Susan L. Hiatt .
letter. I also indicated that a formal decision would be issued in the reasonably near future.
For the reasor s set forth in the enclosed Director's Decision under 10 CFR 2.206, 00-88-10, your Petition has been denied. A copy of the Decision will be referred to the Secretary of the Commission for the Commission's review in accordance with 10 CFR 2.206(c) of the Conmission's regulations.
As provided by this regulation, the Decision will constitute the final action of the Commission 25 days after the date of issuance of the Decision unless the Commission, on its own motion, institutes a review of the Decision within that time. For your information, I have enclosed a copy of the notice regarding this Decision.that has been filed with the Office of the Federal Register for publication.
Sincerely,
- v 2k Thomas E. Murley, Director Office of Nuclear Reactor Regulation
Enclosures:
- 1. Director's Decision
- 2. Federal Register Notice 1
00-88-10 UNITED STATES OF AMERICA NUCLEAR REGULATORY COMMISSION OFFICE 0F NUCLEAR REACTOR REGULATION Thomas E. Murley, Director In the Matter of CLEVELAND ELECTRIC ILLUMINATING Docket Nos. 50-440 COMPANY, ET AL. 50-441 (Perry Nuclear Power Plant, (10 CFR 2.206)
Units 1 & 2) )
DIRECTOR'S DECISION UNDER 10 CFR 2.206 INTRODUCTION On January 22, 1988, Ms. Susan L. Hiatt on behalf of Ohio Citizens for Responsible Energy, Inc. (Petitioner) filed with the Director of the Office of Nuclear Reactor Regulation of the Nuclear Regulatory Conunission (NRC) a "Petition for Immediate Action to Relieve Undue Risk Posed by the Inadequate Seismic Design of the Perry Nuclear Power Plant" requesting a variety of relief including imediate suspension of the operating license (0L) for the Perry Nuclear Power Plant, Unit 1, and suspension of the construction permit (CP) for the Perry Nuclear Power Plant, Unit 2, of the Cleveland Electric IlluminatingCompany,etal.II(Licensees).
1/ Cleveland Electric Illuminating Company is authorized to act as agent for Duquesne Light Company, Ohio Edison Company, Pennsylvania Power Company, and the Toledo Edison Company and has exclusive responsibility and control over the physical construction, operation, and maintenance of the facility.
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The Petitioner also requested that, before reinstating the OL for Perry Unit 1 and the CP for Perry Unit 2, the Licensees should be required to engage in appropriate geologic and geophysical research, including but not limited to confinnatory studies recommended by Petitioner, to determine the appropriate safe-shutdown earthquake (SSE) for the PNPP.
Additionally, the Petitioner requested that the Licensees be required to evaluate whether applicable systems, structures, and components important to safety will remain functional throughout their design life and withstand the vibratory ground motion (and concurrent normal and accident loads) resulting from the earthquake which appropriate geologic and geophysical research reveals to be the proper SSE for the Perry facility. If any system, structure, or component were unable to withstand the appropriate SSE, l
corrective action should be taken and an adjudicatory hearing should be held to determine whether the corrective actions taken are sufficient. Should i
the corrective actions not be completed as specified, the Petitioner
! requested that the OL and CP for Perry Units 1 and 2, respectively, be revoked.
l The Petition's allegations are based largely upon an analysis of data and evaluations that had been performed by other groups in response to the
- January 31, 1986 earthquake that occurred near the Perry facility. The analysis was perfonned for the Petitioner by Dr. Yash Aggarval, and his affidavit and report (Aggarwal Report) are attached to the Petition.
The Aggarval Report notes that, on January 31, 1986, an earthquake with a magnitude of 5.0 occurred with an epicenter about 10 miles south of the l
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l PNPP. Dr. Aggarwal concluded (a) that the January 1986 earthquake and historical seismicity can be associated with a tectonic structure (fault) revealed by magnetic data; (b) that this fault passes within a few miles of the PNPP and is capable of generating much larger earthquakes; (c) that an earthquake with a magnitude of 6.5 is a realistic probability for the purposes of determining the proper SSE for Perry; and (d) that the present magnitude of 5.3 0.5 for the SSE does not provide an adequate margin of safety required for the PNPP. The Petitioner alleges for these reasons that the Licensees are in noncompliance with various regulations of the Comission, specifically, 10 CFR Part 50, Appendix A, General Design Criterion 2, and 10 CFR Part 100, Appendix A, Parts IV, Y, and VI.
On March 2, 1988, I acknowledged receipt of the Petition and explained to the Petitioner my reasons for declining to take any immediate actions. I indicated that I would issue a final decision in this matter in the reasonably near future. My decision in this matter follows.
DISCUSSION The basis for the Petition is the Aggarwal Report. In his report, Dr. Agganfal asserts that an earthquake with a magnitude of 6.5 or larger is probable on a "feature" that, at its closest approacn, is approximately 10 kilometers southeast of the Perry site. This feature is a "boundary" in the magnetic map of Ohio which separates a region of relatively high magnetic relief to the northwest from a region of relatively low magnetic rel4f to the southeast. Weston Geophysical Corporation identified this bo.ndary as the "Akron Magnetic Boundary" (AMB) (Reference 1, Figure 4-2). Lr. Aggarwal
. concludes that correlations of magnetic data and "macroearthquakes" known to have occurred historically within 50 miles of the 1986 event strongly suggest that the AMB marks the locus of a pre-existing fault or fault zone which must be considered capable of generating an earthquake much larger than the magnitude 5.0 earthquake of January 31, 1986. Dr. Aggarwal concludes that a magnitude 6.5' earthquake is a reasonable possibility for purposes of determining the safe-shutdown earthquake for the Perry facility.
( Dr. Aggarwal based his findings, to a large extent, on his analysis of recent studies performed by Weston Geophysical Corporation (Reference 1) on behalf of the Licensees, by the U. S. Geological Survey (Reference 2) on l behalf of the U. S. Nuclear Regulatory Commission (NRC), and on testimony before the U. S. House of Representatives by Dr. L. Seeber (Reference 3).
Since the occurrence of the earthquake on January 31, 1986 in the l vicinity of the Perry site, numerous investigations have taken place to study that earthquake, its aftershocks, and the possible causative structure. The concerns enumerated by Dr. Aggarwal above regarding the adequacy of the SSE for the Perry facility have been discussed extensively l
l in supplements to the Perry Safety Evaluation Report (SER) (Reference 4) prepared by the NRC Staff. The conclusions arrived at by the NRC Staff after reviewing all available pertinent information on the geological and geophysical characteristics of the northeastern region of Ohio were that no l
l discernible geological structure had been identified that could be associated with the earthquake of January 31, 1986, that the earthquake by itself was not uncharacteristic of the general earthquake history of the tectonic province (Central Stable Region) in which the Perry Nuclear Power I
l
Plant is located, and that SSE for Perry of magnitude 5.310.5-remained appropriate. The Staff still considers these conclusions to be valid.
Since the publication of the above supplements to the Perry SER, the Licensees have continued monitoring the seismic activity in the vicinity of the Perry site. Five quarterly reports have been reviewed by the NRC (References 5-9). The cumulative activity recorded by the seismic monitoring network (Reference 9, Figure 4) exhibits some microseismic activity in the corridor covered by the network. The epicentral locations of these very small tremors (with a magnitude range of -0.7 to 1.3) form a small cluster, parallel to and slightly offset from the AMB. The experience of the NRC Staff indicatos that the occurrence of rece ded earthquakes of this size are typical of many locations within the Eastern United States. Further they are only detectable when a highly sensitive seismic network such as that I
employed by the Licensees is used. These events by themselves do not indicate potential for large and possibly damaging earthquakes.
l The NRC has also received a Preliminary Report (Reference 10) that dis-cusses the earthquake of July 13, 1987, at Ashtabula, Ohio, and its aftershock sequence. In addition to the discussions on the Ashtabula event of 1987, the i
Preliminary Report also mentions the earthquake of January 31, 1986 at Chardon, Ohio. The authors, including Dr. Seeber who originally provided testimony concerning the event (Reference 3), recognize, as Dr. Aggamal did, the association of this event with the NNE trending AMB and suggest that the association may indicate that the magnetic feature could be an expression of a reactivated fault of considerable length on which earthquakes much larger l than the 1986 event could occur. However, it should be pointed out that the
. authors of this Preliminary Report themselves state that, because of the lack of any evidence of the extension of this postulated fault irito the Paleozoic platform cover (upper 2 kilometers of rock strata), very large ruptures involving much of any postulated fault are unlikely. For reasons which are discussed below in response to Dr. Aggarwal's specific arguments, the Staff continues to be of th'e view that the existing seismic design at Perry is appropriate and in compliance with the requirements of 10 CFR Part 100, Appendix A.
Dr. Aggamal raises two arguments to support his view that the present SSE for the Perry facility is inadequate. First, Dr. Aggarwal argues that the main shock and aftershock focal mechanisms of the January 31, 1986 earthquake indicate a fault approximately N30*E colinear with the AMB.
While a general NNE trend of the main shock and aftershock focal mechanisms appears to be inferred, the uncertainty associated with Dr. Aggarwal's prr.ferred orientation is larger than he indicates. For example, the most recent study of the 1986 earthquake (Reference 11) indicates that the northeast trending plane of the main shock could vary from N22*E to N55*E depending upon the type of seismic wave analyzed. Dr. Aggarwal appears to be incorrect in his assertion that Hernnann and Nguyen (Reference 12) defined a possible source of the earthquake as being a N28'E westward dipping fault (82*). Dr. Herrmann (Personal Communication 1988) indicated that this possible source would be a N21*E eastward dipping fault.
Dr. Aggamal next argues that several of the earthquakes that occurred in recent history have a sufficient error band in their epicentral location that they also can be associated with the AMB and that this correlation
_7 implies the existence of a fault on which the occurrence of an earthquake much larger than the earthquake of January 31, 1986 must be considered a realistic possibility. The Staff disagrees with this assertion and bases its conclusion on this matter on the following observations:
- 1. The earthquake of January 31, 1986 itself is not uncharacteristic of the general earthquake history of the tectonic province, which includes the 1937 earthquake at Anna, Ohio; the 1982 earthquake at Sharpsburg, Kentucky; and many other earthquakes in the range of magnitude of 5.0 to 5.3.
- 2. The nature and depth of the geologic feature or features manifested by the AMB have tot been determined. Throughout the Eastern United States, the"e are many magnetic features and many earthquakes the size of the 1986 Ohio event. Some of these earthquakes are near anomalous magnetic features, and others are not. Magnetic boundaries indicate changes in rock properties. However, these changes in rock properties do not necessarily indicate faults or support that the indicated faults are active and capable of large ruptures.
- 3. Dr. Aggarwal is of the opinion that the macroseismicity criterion in Appendix A to 10 CFR Part 100 can be used to identify the AMB as a capable fault. Past use of macroseismicity to identify capable faults has proven to be a difficult process. Macroseismicity has been considered to be a level of seismicity that implies significant, sustained, and coherent tectonic activity representative of a major defonnational movement within the earth's crust (Reference 13). Aside from the well-located 1986 earthquake, Dr. Aggarwal has identified six other
- earthquakes, one with a_ magnitude of 4.7 and five in the magnitude range of 2.7 to 3.8, that have occurred sirice 1885 that, because of location uncertainties, could conceivably be associated with the AMB.
Such correlations based upon historic earthquakes, many of which are demonstrably associated with large uncertainties in location, have not in the past proven to be definitive indicators of earthquake sources.
Moreover, the statement by Dr. Aggarwal that the data strongly suggest a causal relationship between earthquakes and the AMB is questionable because he ignores the fact that there are other earthquake occurrences in nearby northeastern Ohio whose locations cannot be associated with the AMB. For example, several earthquakes have occurred to the west of the AMB, between that feature and the city of Cleveland. Most recently, the earthquake of July 13, 1987, with a magnitude of 3.6, discussed in Reference 10, a very well-located event, occurred some 25 kilometers east of the AMB on an east-west trending fault. Therefore, the small l
number of earthquakes used by Dr. Aggarwal to support his correlation, most of which are less than a magnitude of 4, the uncertainties in their location, and the occurrence of earthquakes in areas not associated with the AMB do not, in the Staff's opinion, support use of macroseismicity to identify a capable fault.
- 4. Dr. Aggarwal argues that even if the AMB cannot be identified as a capable fault, a higher SSE than presently assigned to Perry is needed since Appendix A to 10 CFR Part 100 indicates that if seismological and geological data warrant, the SSE shall be larger than that derived by the normal procedures outlined in the regulations. In the procedures
F
.g.
provided by Appendix A, the SSE is determined by assuming the reoccurrence at the site of the largest historic earthquake that has occurred in the tectonic province within which the site is located. In Dr. Aggarwal's view, the seismological and geological data he presented imply the existence of a fault which could cause a significantly larger aarthquake.
As discussed above, the NRC staff does not believe the data warrant the existence of such a fault and the need to use an SSE larger than that defined by nonnal licensing procedures.
The Staff has determined that the arguments presented in the Aggarwal Report indicating the presence of a large fault that could generate an earthquake with a magnitude of 6.5 or greater in the vicinity of the Perry Nuclear Power Plant are not persuasive. The Staff reaffirms its conclusion that the seismic design for the Perry facility is appropriate. Therefore, the request for a suspension of the Perry licenses until additional geological and geophysical studies and engineering evaluations are completed is unwarranted.
Also, given the continued acceptability of the SSE for the Perry facility, the allegations by Petitioner that the Perry facility is in noncortpliance with the Commission's regulations in the area of seismic design are unwarranted.
In particular, the Petitioner calls into question the seismic capability of the 8x8 fuel spacer utilized at the Perry facility. The allegation is based upon the occurrence of a near-field magnitude 6.5 earthquake and exposure of the spacer to the resultant acceleration in excess of 0.3 g. Our above evaluation indicates that consideration of such an earthquake is inappropriate, therefore concerns related to the seismic capability are unwarranted.
l In the absence of a substantial health and safety issue, I decline to grant relief requested by Petitioner pursuant to 10 CFR 2.206. See Consolidated Edison Co. of New York (Indian Point, Units 1, 2, and 3),
CLI-75-8, 2 NRC 173, 176 (1975); Washington Public Power Supply System (WPPSS Nuclear Project No 2), DD-84-7,19 NRC 899, 923 (1984). The northeastern Ohio region is an area of continuing investigation by the NRC, university groups, and the Licensees, which, as indicated previously, are monitoring microseismicity in the vicinity of the Perry plant. The Staff is keeping abreast of studies being performed in the region and will evaluate the resulting reports with respect to any changes that might be required in the above conclusions and any effect such changes might have upon the seismic safety of the Perry plant. 2/
CONCLUSION For the reasons discussed above, I have concluded that no adequate basis exists for suspending the OL for Perry Unit 1 and the CP for Perry Unit 2. I have also concluded that the geologic and geophysical research and studies requested of the Licensees by the Petitioner also are unnecessary.
U Th e Staff has recently received a June 8,1988 response to the Petition filed by the Licensees. The response contains an enclosure, "Analyses of North-eastern Ohio Seismicity and Tectonics," dated June 1988, prepared by Weston Geophysical Corporation. A review of the Licensees' response indicates that it contains infonnation that supports the Staff's conclusions with regard to the Petition. Since the Staff does not intend to study this document further it is not basing its conclusions in whole or in part upon this response by the Licensees.
.___ - ____ _ J
. I have further concluded that, because the Staff does not consider the SSE for the Perry Nuclear Power Plant to be in question, corrective actions and an adjudicatory hearing to judge the adequacy of those corrective actions are unwarranted. Accordingly, the Petitioner's request for action pursuant to 10 CFR 2.206 is denied.
As provided in 10 CFR 2.206(c), a copy of this decision will be filed with the Secretary of the Comissio6 for the Comission's review.
FOR ThE NUCLEAR REGULATORY COMMISSION Thomas E. Murley, Director Office of Nuclear Reactor Regulation Dated at Rockville, Maryland this 22ndday of June 1988
References
- 1. Weston Geophysical Corporation: "Investigations of Confirmatory Seismological and Geological Issues. Northeastern Ohio Earthquake of January 31, 1986," dated June 1986,
- 2. U.S. Geological Survey: "Studies of the January 31, 1986 Northeastern Ohio Earthquake." Open File Report 86-331, 1986.
- 3. Leonardo Seeber: "Testimo,ny before the Subcomittee on Energy and the Environment Committee on Interior and Insular Affairs of the U.S. House of Representatives." April 8, 1986.
- 4. Safety Evaluation Report Related to the Operation of Perry Nuclear Power Plant, Units 1 and 2, NUREG-0887, Supplements No. 9, March 1986, and No. 10, September 1986.
- 5. Weston Geophysical Corporation: "Quarterly Progress Report," Cleveland Electric Illuminating Company, et al. (CEI) Seismic Monitoring Program for Northeastern Ohio, October 15, 1986 - January 15, 1987.
- 6. Weston Geophysical Corporation: "Second Quarterly Report," CEI Seismic Monitoring Network, January 15 - April 15,1987.
- 7. Weston Geophysical Corporation: "Third Quarterly Report," CEI Seismic Monitoring Network, April 16 - July 15, 1987.
- 8. Weston Geophysical Corporation: "Fourth Quarterly Report," CEI Seismic Monitoring Network, July 16 - October 15, 1987, issued December 1987.
- 9. Weston Geophysical Corporation: "Fifth Quarterly Report," CEI Seismic Monitoring Network, October 16 - December 31, 1987, issued February 1
1988.
- 10. L. Seeber and J. G. Armbruster, Lamont-Doherty Geological Observatory of Columbia University: "Recent and Historic Seismicity in Northeastern Ohio: Reactivation of Precambian Faults and the Role of Deep Fluid Injection," Preliminary Report to the U.S. NRC.
- 11. C. Nicholson, E. Roeloffs, and R. L. Wesson: "The Northeastern Ohio Earthquake of 31 January 1986: Was It Induced?" Bulletin of the Seismological Society of America, Volume 78, No. 1, February 1988.
- 12. Herrmann, R. B., and B. V. Nguyen: "Focal Mechanism Studies of the January 31, 1986 Perry Ohio Earthquake" (abstract), Earthquake Notes, Volume 57, page 107, October 1986.
- 13. SECY-97-300. Identification of issues pertaining to seismic and geologic siting regulation, policy, and practice for nuclear power plants. April 27, 1979.
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7590-01 UNITED STATES NUCLEAR REGULATORY COMMISSION DOCKET NOS. 50-440 AND 50-441 CLEVELAND ELECTRIC ILLUMINATING COMPANY, ET AL.
PERRY NUCLEAR POWER PLANT, UNIT NOS. 1 AND 2
_I_SSUANCE OF DIRECT'OR'S DECISION UNDER 10 CFR 2.206 l Notice is hereby given that the Director, Office of Nuclear Reactor
! Regulation, has issued a Director's Decision concerning a Petition dated January 22, 1988, filed by Susan L. Hiatt on behalf of Ohio Citizens for Responsible Energy, Inc. (Petitioner). The Petitioner requested that the l Nuclear llegulatory Commission (NRC) grant a variety of relief, including suspension of the operating license for the Perry Nuclear Power Plant, Unit 1
1, and suspension of the construction permit for the Perry Nuclear Power Plant, Unit 2. The Petition alleged various seismic inadequacies in the l
Perry Nuclear Power Plant design, specifically:
- 1. The earthquake of January 31, 1986, at Chardon, Ohio and the historic seismicity near the Perry Nuclear Power Plant can be associated with a tectonic structure (fault) that has been revealed by magnetic data.
i
- 2. This tectonic structure is capable of an earthquake with a magnitude of 6.5 or greater.
- 3. The present safe-shutdown earthquake (magnitude of 5.3 0.5) for the Perry facility does not provide the margin of safety required.
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On the basis of these alleged inadequacies, Petitioner claimed that the Perry facility did not comply with the Comission's requirements related to seismic design.
On March 2,1988, the Director of the Office of Nuclear Reactor Regulation acknowledged receipt of the Pefition and notified the Petitioner that this matter would be considered pursuant to 10 CFR 2.206.
The Director has determined that the Petitioner's request 3hould be denied. The reasons for the denial are set forth in the "Director's Decision Pursuant to 10 CFR 2.206" (DD-88-10 ), which is available for inspection and copying in the Comission's Public Document Room,1717 H Street, N.W., Washington, D.C. 20555 and at the local public document room for the Perry Nuclear Powcr Plant at the Perry Public Library, 3753 Main Street, Perry, Ohio 44081.
A copy of the decision will be filed with the Secretary of the Comission for the Comission's review in accordance with 10 CFR 2.206(c).
As provided in 10 CFR 2.206(c), the decision will become the final action of the Comission 25 days after issuance unless the Comission on its own motica institutes review of the decision within that time.
i FOR THE NUCLEAR REGULATORY COMMISSION
~
N Thomas E. Murley, Director l Office of Nuclear Reactor Regulation l
! Dated at Rockville, Maryland this 22nd day of June 1988 1
- NRC FORM 8 (4-79)
NRCM 0240 E!
g-E 1 5 m
i t
INCOMING AND SIGNATURE TAB Use this side of the sheet to precede the incoming material when assembling correspondence.
(USE REVERSE SIDE FOR SIGNATURE TAB) 1 - _ _ _ . _ _ _ _ _ _ . _ _ _ _ _ _ _ . . _ _ _ _ _ _ _ _ _ _
June 22, 1988 DISTRIBUTION: ,
- 1 Dock _t Files w/ificomings NRC & Local PORs ED0#0003493 ED0 Reading TMurley.JSniezek TMartin, NRR FMiraglia KPerkins GHolahan Gi)1espie DCrutchfield PKreutzer TColburn GPA/PA DMossburg PMAS(ED0#0003493) PDIII-3 r/f Docket Nos. 50-440 DHagan VStello and 50-441 Bill Clements, SECY(5) OGC-WF1 ;
JLieberman ASLAB l (10 CFR Section 2.206) ASLBP ACRS(10)
JResner(2)(U-501)
Ms. Susan L. Hiatt Ohio Citizens for Responsible Energy, Inc. .,
8275 Munson Road Mentor, Ohio 44060
Dear Ms. Hiatt:
This letter responds to the "Petition for Imediate Action to Relieve Undue Risk Posed by the Inadequate Seismic Design of the Perry Nuclear Power Plant" filed by you on behalf of the Ohio Citizens for Responsible Energy, Inc. (Petitioner) on January 22, 1988 pursuant to 10 CFR 2.206. The Petition made the following allegations regarding the seismic design of the Perry Nuclear Power Plant Companyetal.(Licensees)(:PNPP) of the Cleveland Electric Illuminating
- 1. The carthquake of January 31, 1986 at Chardon, Ohio and the historic seismicity near the PNPP can be associated with a tectonic structure (fault) that has been revealed by magnetic data.
- 2. This tectonic structure is capable of an earthquake with a magnitude of 6.5 or greater.
- 3. Thepresentsafe-shutdownearthquake(SSE)ofmagnitudeof5.3 0.5 for the PNPP does not provide an adequate rargin of safety.
Based on these allegations, the Petition concluded that the PNPP does not comply with the Commission's regulations regarding seismic derign required '
by 10 CFR Part 50, Appendix A, General Design Criterion 2, and 10 CFR Part 100. Appendix A. Parts IV, V, and VI. ;
! The Petition requested an imediate suspension of the operating license (OL) for PNPP Unit 1 and the construction pennit (CP) for PNPP Unit 2. It further requested that additional geologic and geophysical studies be conducted, and appropriate corrective actions considered, by the Licensees and that an adjudicatory hearing be held to evaluate the effectiveness of l
those corrective actions.
On March 2,1988, I sent you a letter acknowledging receipt of the Petition and declined to take any imediate action for the reason stated in that l
Ms. Susan L. Hiatt letter. I also indicated that a formal decision would be issued in the reasonably near future.
For the reasons set forth in the enclosed Director's Decision under 10 CFR 2.206, DD-88-10, your Petition has been denied. A copy of the Decision will be referred to the Secretary of the Comission for the Comission's review in accordance with 10 CFR 2.206(c) of the Comission's regulations.
As provided by this regulation, the Decision will constitute the final action of the Comission twenty-five days after the date of issuance of the Decision unless the Comission, on its own motion, institutes a review of the Decision within that time. For your information, I have enclosed a copy of the notice regarding this Decision that has been filed with the Office of the Federal Register for publication.
Sincerely, Original signed b7; ,
pgs E. y.uricY.
Thomas E. Murley, Director Office of Nuclear Reactor Regulation
Enclosures:
- 1. Director's Decision
- 2. Federg Register Notice l
- SEE PREVIOUS CONCURRENCE
- Office
- LA/PDIII-3 PM/PDIII-3 PD/PDIII-3 OGC Surname: *PXreutzer *TColburn/tg *KPerkins *LChandler Date: 05/13/88 05/13/88 05/13/88 06/09/38 Office: AD/DRSP D/DRSP AD W Suraame: *GHolahan *DCrutchfield *FMiraglia jt1Murley g
Date: 05/27/88 05/27/88 05/27/88 h /tM88
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DD-88-10 UNITED STATES OF AMERICA NUCLEAR REGULATORY COMMISSION OFFICE OF NUCLEAR REACTOR REGULATION Thomas E. Marley, Director In the Matter of CLEVELAND ELECTRIC ILLUMINATING' Docket Nos. 50-440 COMPANY, ET AL. 50-441 (Perry Nuclear Power Plant, (10CFR2.206)
Units 1 & 2) )
DIRECTOR'S DECISION UNDER 10 CFR 2.206 INTRODUCTION On January 22, 1988, Ms. Susan L. Hiatt on behalf of Ohio Citizens for Responsible Energy, Inc. (Petitioner) filed with the Director of the Office of Nuclear Reactor Regulation of the Nuclear Regulatory Comission (NRC) a "Petition for Immediate Action to Relieve Undue Risk Posed by the Inadequate Seirmic Design of the Perry Nuclear Power Plant" requesting a variety of relief including imediate suspension of the operating lic.ense (OL) for the Perry Nuclear Power Plant, Unit 1, and suspension of the construction permit (0P) for the Perry Nuclear Power Plant, Unit 2, of the Cleveland Electric IlluminatingCompany,etal.1/(Licensees).
1/ Cleveland Electric Illuminating Company is authorized to act as agent for Duquesne Light Company, Ohio Edison Company, Pennsylvania Power Company, and the Toledo Edison Company and has exclusive responsibility and control over the physical construction, operation, and maintenance of the facility, i
The Petitioner also requested that, before reinstating the OL for Perry Unit 1 and the CP for Perry Unit 2, the Licensees should be required to engage in appropriate geologic and geophysical research, including but not limited to confirmatory studies recommended by Petitioner, to determine the appropriate safe-shutdowr. earthquake (SSE) for the PNPP.
Additionally, the Petitiorfer requested that the Licensees be required to evaluate whether applicable systems, structures, and components important to safety will remain functional throughout their design life and withstand the vibratory ground motion (and concurrent normal and accident loads) resulting from the earthquake which appropriate geologic and geophysical research reveals to be the proper SSE for the Perry facility. If any system, structure, or component were unable to withstand the appropriate SSE, corrective action should be taken and an adjudicatory hearing should be held to determine whether the corrective actions taken are sufficient. Should the corrective actions not be completed as specified, the Petitioner rcquested that the OL and CP fer Perry Units 1 aid 2, respectively, be revoked.
The Petition's allegations are based largely upon an analysis of data and evaluations that had been performed by other groups in response to the January 31, 1986 earthquake that occurred near the Perry facility. The analysis was performed for the Petitioner by Dr. Yash Aggarwal, and his l
affidavit and report (Aggarwal Report) are attached to the Petition.
The Aggarwal Report notes that, on January 31, 1986, an earthquake with a magnitude of 5.0 occurred with an epicenter about 10 miles south of the l
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- PNPP. Dr. Aggarwal concluded (a) that the January 1986 earthquake ano historical seismicity can be associated with a tectonic structure (fault) revealed by magnetic data; (b) that this fault passes within a few miles of the PNPP and is capable of generating much larger earthquakes; (c) that an earthquake with a magnitude of 6.5 is a realistic probability for the purposes of determining the pro'per SSE for Perry; and (d) that the present magnitude of 5.3 0.5 for the SSE does not provide an adequate margin of safety required for the PNPP. The Petitioner alleges for these reasons that the Licensees are in noncompliance with various regulations of the Commission.
specifically,10 CFR Part 50, Appendix A, General Design Criterion 2, and 10 CFR Part 100, Appendix A, Parts IV, V, and VI.
On March 2,1988, I acknowledged receipt of the Petition and explained to the Petitioner my reasons for declining to take any in diate actions. I indicated that I would issue a final decision in this matter in the reasonably near future. My decision in this matter follows.
DISCUSSION The basis for the Petition is the Aggarwal Report. In his report, Dr. Aggarwal asserts that an eartN~ sake with a magnitude of 6.5 or larger is probable on a ' feature" that, at its closest approach, is approx'mately 10 kilometers southeast of the Perry site. This feature is a "bo;ndary" in the magnetic map of Ohio which separates a region of relatively high magnetic relief to the northwest from a region of relatively low magnetic relief to the southeast. Weston Geophysical Corporation identified this boundary as the "Akron Magnetic Boundary" (AMB) (Reference 1, Figure 4-2). Dr. Aggarwal
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concludes that correlations of magnetic data and ":nacroearthquakes" known to have occurred historically within 50 miles of the 1986 event strongly suggest that the AMB marks the locus of a pre-existing fault or fault zone which must be considered capable of generating an earthqur's much larger than the magnitude 5.0 earthquake of J;nuary 31, 1986. Dr. Aggarwal concludes that a magnitude 6.5' earthquake is a reasonable possibility for purposes of determirdng the safe-shutdown earthquake for the Perry facility.
Dr. Aggarwal based his findings, to a large extent, on his analysis of recent studies performed by Weston Geophysical Corporatinn (Reference 1) on behalf of the Licensees, by the U. S. Geological Survey (Reference 2) on behalf of the U. S. Nuclear Regulatory Commission (NRC), and on testimony before the U. S. House of Representatives by Dr. L. Seeber (Reference 3).
Since the occurrence of the earthquake on January 31, 1986 in the vicinit.y of the Perry site, numerous investigations have taken place to study that earthquake, its aftershocks, and the possible causative structure. Thc concerns enumerated by Dr. Aggarwal above regarding the adequacy of the SSE for the Perry facility have been discussed extensively in supplements to the Perry Safety Evaluation Report (SER) (Reference 4) prepared by t'1e NRC Staff. The conclusions arrived at by the NRC Staff after reviewing all available pertinent information on the geological and geophysical characteristics of the northeastern region of Ohio were that no discernible geological structure had been identified that could be associated with the earthquake of January 31, 1986, that the earthquake by itself was not uncharacteristic of the general earthquake history of the tectonic province (Central Stable Region) in which the Perry Nuclear Power j
. Plant is located, and that SSE for Perry of magnitude 5.310.5 remained appropriate. The Staff still considers these conclusions to be valid.
Since the publication of the above supplements to the Perry SER, the Licensees have continued monitoring the seismic activity in the vicinity of the Perry site. Five quarterly reports have been reviewed by the NRC (References 5-9). The cumulative activity recorded by the seismic monitoring network (Reference 9, Figure 4) exhibits some microseismic activity in the corridor covered by the network. The epicentral locations of these very small tremors (with a magnitude range of -0.7 to 1.3) form a small cluster, parallel to and slightly offset from the AMB. The experience of the NRC Staff indicates that the occurrence of recorded earthquakes of this size are typical of many locations within the Eastern United States. Further they are only detectable when a highly sensitive seismic network such as that employed by the Licensees is used. These events by themselves do not indicate potential for large and possibly damaging earthquakes.
The NRC has also received a Preliminary Report (Reference 10) that dis-cusses the earthquake of Juls 13, 1987, at Ashtabula, Ohio, and its aftershock j sequence. In addition to the discussions on the Ashtabula event of 1987, the Preliminary Report also mentions the earthqueke of January 31, 1986 at Chardon, l Ohio. The authors, including Dr. Seeber who originally provided testimony concerning the event (Reference 3), recognize, as Dr. Aggarwal did, the association of this event with the NNE trending AMB and suggest that tne association may indicate that the magnetic feature could be an expression of a reactivated fault of considerable length on which earthquakes much larger i than the 1986 event could occur. However, it should be pointed out that the 1
,. authors of this Preliminary Report themselves state that, because of the lack of any evidence of the extension of this postulated fault into the Paleozoic platform cover (upper 2 kilometers of rock strata), very large ruptuces involving much of any postulated fault are unlikely. For reasons which are discussed below in response to Dr. Aggarwal's specific arguments, the Staff continues to be of tne view that the existing seismic design at Perry is appropriate and in compliance with the requirements of 10 CFR Part 100, Appendix A.
Dr. Aggamal raises two arguments to support his view that the present SSE for the Perry facility is inadequate. First, Dr. Aggarwal argues that the main shock and aftershock focal mechanisms of the January il,1986 earthquake indicate a fault approximately N30'E colinear wit' he AMB.
While a general NNE trend of the main shock and aftershock focal mechanisms appears to be inferred, the uncertainty associated with Dr. Aggarwal's preferred orientation is larger than he indicates. For example, the most recent study of the 1986 earthquake (Reference 11) indicates that the l-northeast trending plane of the main shock could vary from N22*E to N55*E depending upon the type of seismic wave analyzed. Dr. Aggarwal appears to be incorrect in his assertion that Herrmann and Nguyen (Reference 12) defined l a possible source of the earthquake as being a N28'E westward dipping fault (82'). Dr. Herrmann (Personal Connunication 1988) indicated that this l possible source would be a N21'E eastward dipping fault.
Dr. Aggamal next argues that several of the earthquakes that occurred in recent history have a sufficient error band in their epicentral location that they also can be associated with the AMB and that this correlation i
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$, implies the existence of a fault on which the occurrence of an earthquake much larger than the earthquake of January 31, 1986 must be considered a realistic possibility. The Staff disagrees with this assertion and bases its conclusion on this matter on the following observations:
- 1. The earthquake of January 31, 1986 itself is not uncharacteristic of the general earthquake history of the tectonic province, which includes the 1937 earthquake at Anna, Ohio; the 1982 earthquake at Sharpsburg, Kentucky; and many other earthquakes in the range of magnitude of 5.0 to 5.3.
- 2. The nature and depth of the geologic feature or features manifested by the AMB have not been detennined. Throughout the Eastern United States, there are many magnetic features and many earthquakes the size of the 1986 Ohio event. Some of these earthquakes are near anomalous magnetic features, and others are not. Magnetic boundaries indicate changes in rock properties. However, these changes in rock properties do not necessarily indicate faults or support that the indicated faults are activa and capable of large ruptures.
- 3. Dr. Aggamal is of the opinion that the macroseismicity criterion in Appendix A to 10 CFR Part 100 can be used to identify the AMB as a capable fault. Past use of macroseismicity to identify capable faults has proven to be a difficult process. Macroseismicity has been considered to t,a a level of seismicity that implies significant, sustained, and coherent tectonic activity representative of a major deformational movement within the earth's crust (Reference 13). Aside from the well-located 1986 earthquake, Dr. Aggarwal has identified six other l
earthquakes, one with a magnitude of 4.7 and five in the magnitude range of 2.7 to 3.8, that have occurred since 1885 that, because of location uncertainties, could conceivably be associated with the AMB.
Such correlations based upon historic earthquakes, many of which are demonstrably associated with large uncertainties in location, have not in the past proven to be definitive indicators of earthquake sources.
Moreover, the statement by Dr. Aggarwal that the data strongly suggest a causal relationship between earthquakes and the AMB is questionable because he ignores the fact that there are other earthquake occurrences in nearby northeastern Ohio whose locations cannot be associated with the AMB. For example, several earthquakes have occurred to the west of the AMB, between that feature and the city of Cleveland. Most recently, the earthquake of July 13, 1987, with a magnitude of 3.6, discussed in Reference 10, a very well-located event, occurred some 25 kilometers east of the AMB on an east-west trending fault. Therefore, the small nuniber of earthquakes used by Dr. Aggarwal to support his correlation, most of which are less than a magnitude of 4, the uncertainties in their location, and the occurrence of earthquakes in areas not associated with the AMB do not, in the Staff's opinion, support use of macroseismicity to identify a capable fault.
- 4. Dr. Agga mal argues that even if the AMB cannot be identified as a capable fault, a higher SSE than presently assigned to Perry is needed since Appendix A to 10 CFR Part 100 indicates that if seismological and geological data warrant, the SSE shall be larger than that derived by the normal procedures outlined in the regulations. In the procedures
j
.. provided by Appendix A, the SS2 is determined by assuming the reoccurrence at the site of the largest historic earthquake that has occurred in the tectonic province within which the site is located. In Dr. Aggarwal's vicw, the seismological and geological data he presented imply the existence of a fault which could cause a sigaificantly larger earthquake.
Asdiscussedabove,theNiiCstaffdoesnotbelievethedatawarrantthe existence of such a fault and the need to use an SSE larger than that defined by nonnal licensing procedures.
The Staff has determined that the arguments presented in the Aggarwal Report indicating the presence of a large fault that could generate an earthquake with a magnitude of 6.5 or greater in the vicinity of the Perry Nuclear Power Plant are not persuasive. The Staff reaffirms its conclusion that the seismic design for the Perry facility is appropriate. Therefore, the request for a suspension of the Perry licenses until additional geological and geophysical studies and engineering evaluations are completed is unwarranted.
Also, given the continued acceptability of the SSE for the Perry facility, the allegations by Petitioner that the Perry facility is in noncompliance with the Commission's regulations in the area of seismic design are unwarranteri.
In particular, the Petitioner calls into question the seismic capability of the 8x8 fuel spacer utilized at the Perry facility. The allegation is based upon the occurrence of a near-field magnitude 6.5 earthquake and exposure of the spacer to the resultant acceleration in excess of 0.3 g. Our above evaluation indicates that consideration of such an earthquake is inappropriate, therefore concerns related to the seismic capability are unwarranted.
In the absence of a substantial health and safety issue, I decline to grant relief requested by Petitioner pursuant to 10 CFR 2.206. See Consolidated Edison Co. of New York (Indian Point, Units 1, 2, and 3),
CLI-75-8,2NRC173,176(1975); Washington Public Power Supply System (WPPSSNuclearProjectNo 2),00-84-7,19NRC899,923(1984). The northeastern Ohio region is an area of continuing investigation by the NRC, university groups, and the Licensees, wMeh, as indicated previously, are monitoring microseismicity in the vicinity of the Perry plant. The Staff is keeping abren t of studies being performed in the region and will evaluate the resulting reports with tapect to any changes that might be required in the above conclusions and any effect such changes might have upon the seismic safety of the Perry plant. S/
CONCLUSION For the reasons discussed above, I have concluded that no adequate basis exists for suspending the OL for Perry Unit 1 and the CP for Perry l Unit 2. I have also concluded that the geologic and geophysical research and studies requested of the Licensees by the Petitioner also are unnecessary.
l EIThe Staff has recently received a June 8,1988 response to the Petition filed by the Licensees. The response contains an enclosure, "Analyses of North-eastern Ohio Seismicity and Tectonics," dated June 1988, prepared by Weston Geophysical Corporation. A review of the Licensees' response indicates that it contains infortnation that supports the Staff's conclusions with regard to the Petition. Since the Staff does not intend to study this document further it is not basing its conclusions in whole or in part upon this response by l the Licensees.
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I have further concluded that, because the Staff does not consider the SSE for the Perry Nuclear Power Plant to be in question, corrective actions and an adjudicatory hearing to judge the adequacy of those corrective actions are unwarranted. Accordingly, the Petitioner's request for action pursuant to 10 CFR 2.206 is denied.
As provided in 10 CFR 2.206(c), a copy of this decision will be filed with the Secretary of the Commission for the Commission's review.
FOR THE NUCLEAR REGULATORY COMMIS$10N if _-
Thomas E. Murley, Director Office of Nuclear Reactor Regulation Dated at Rockville, Maryland this 22ndday of June 1988 l
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Reference,s,
- 1. Weston Geophysical Corporation: "Investigations of Confinnatory Seismological and Geological Issues. Northeastern Ohio _ Earthquake of January 31, 1986," dated June 1986,
- 2. U.S. Geological Survey: "Studies of the January 31, 1986 Northeastern Ohio Earthquake." Open File Report 86-331, 1986.
- 3. Leonardo Seeber: "Testimony before the Subcomittee on Energy and the Environment Comittee on Interior and Insular Affairs of the U.S. House of Representetives." April 8,1986.
- 4. Safety Evaluation Report Related to the Operation of Perry Nuclear Power Plant Units 1 and 2, NUREG-0887, Supplements No. 9, March 1986, and No. 10, September 1986.
- 5. Weston Geophysical Corporation: "Quarterly Progress Report," Cleveland Electric Illuminating Company, et al. (CEI) Seismic Monitoring Program for Northeastern Ohio, October 15, 1986 - January 15, 1987.
- 6. Weston Geophysical Corporation: "Second Quarterly Report," CEI Seismic Monitoring Network, January 15 - April 15, 1987.
- 7. Weston Geophysical Curporation: "Third Quarterly Report," CEI Seismic Monitoring Network, April 16 - July 15, 1987.
- 8. Weston Geophysical Corporation: "Fourth Quarterly Report," CEI Seismic Monitoring Network, Jeiy 16 - October 15, 1987, issued December 1987.
- 9. Weston Geophysical Corporation: "Fifth Quarterly Report," CEI Seisnaic Monitoring Network, October 16 - December 31, 1987, issued February 1988.
- 10. L. Seeber and J. G. Armbruster, Lamont-Doherty Geological Observatory of Columbia University: "Recent and Historic Seismicity in Northeastern Ohio: Reactivation of Precambian Faults and the Role of Deep Fluid Injection," Preliminary Report to the U.S. NRC.
- 11. C. Nicholson, E. Rocloffs, and R. L. Wesson: "The Northeastern Ohio n Earthquake of 31 January 1986: Was It Induced?" Bulletin of the Seismological Society of America, Volume 78, No.1, February 1988.
- 12. Herrmann, R. B., and B. V. Nguyen: "Focal Mechanism Studies of the January 31, 1986 Perry Ohio Earthquake" (abstract), Earthquake Notes.
Volume 57, page 107, October 1986.
! 13. SECY-97-300. Identification of issues pertaining to seismic and geologic siting regulation, policy, and practice for nuclear power plants. April 27, 1979.
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7590-01 UNITED STATES NUCLEAR REGULATORY COMMISSION DOCKET NOS. 50-440 AND 50-441 CLEVELAND ELECTRIC ILLUMINATING COMPANY, ET AL.
PERRY NUCLEAR POWER PLANT, UNIT NOS. 1 AND 2 ISSUANCE OF DIRECTOR'S DECISION UNDER 10 CFR 2.206 Notice is hereby given that the Director, Office of Nuclear Reactor Regulation, has issued a Director's Decision concerning a Petition dated January 22,.1988, filed by Susan L. Hiatt on behalf of Ohio Citizens for ResponsibleEnergy,Inc.(Petitioner). The Petitioner requested that the Nuclear Regulatory Comission (NRC) grant a variety of relief, including suspension of the operating license for the Perry Nuclear Power Plant, Unit 1, and suspension of the construction permit for the Perry Nuclear Power Plant, Unit 2. The Petition alleged various seismic inadequacies in the Perry Nuclear Power Plant design, specifically:
- 1. The earthquake of January 31, 1986, at Chardon, Ohio and the historic seismicity near the Perry Nuclear Power Plant can be associated with a i tectonicstructure(fault)thathasbee)) revealed by magnetic data.
- 2. This tectonic structure is capable of an earthquake with a magnitude of 6.5 or greater.
I
- 3. Thepresentsafe-shutdownearthquake(magnitudeof5.3 0.5) for the Perry facility does not provide the margin of safety required.
1
On the basis of these alleged inadequacies, Petitioner claimed that the Perry facility did not comply with the Comission's requirements related to seismic design.
On March 2,1988, the Director of the Office of Nuclear Reactor Regulation
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acknowledged receipt of the Petition and notified the Petitioner that this matter would be considered pursuant to 10 CFR 2.206.
The Director has determined that the Petitioner's request should be denied. The reasons for the denial are set forth in the "Director's Decision Pursuant to 10 CFR 2.206" (DD-88-10 ), which is available for inspection and copying in the Comission's Public Document Room,1717 H Street, N.W., Washington, D.C. 20555 and at the local public document room for the Perry Nuclear Power Plant at the Perry Public Library, 3753 Main l
Street, Perry, Ohio 44081.
i A copy of the decision will be filed with the Secretary of the I
Comission for the Comission's review in accordance with 10 CFR 2.206(c).
As provided in 10 CFR 2.206(c), the decision will become the final action of the Comission 25 days after issuance unless the Comission on its own motion institutes review of the decision within that time.
FOR THE NUCLEAR REGULATORY COMMISSION
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.:n f Thomas E. Murley, Director Office of Nuclear Reactor Regulation Dated at Rockville, Maryland this 22r.d day of June 1988 ,
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F '2.206 PETITION FOR IMMEDIATE ACTION TO RELIEVE MURLEY
.' UNDUE RISK POSED-BY THE INADEDUATE SEISMIC DESIGN DAVIS L[,i- OF THE PERRY NUCLEAR POWER PLANT .
m v;c m- ,DATE: 02/11/88 ' '
OOC CONTACT: MURRAY
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,> ,a c' s) i UNITED STATES OF AMERICA NUCLEAR REGULATORY COMMISSION Before the Director, Office of Nuclear Reactor Regulation In the Matter of )
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THE CLEVELAND ELECTRIC ILLUMINATING )
COMPANY, ET AL. ) Docket Nos. 50-440/441
) 2.206 Petition (Perry Nuclear Power Plant, Units 1 )
and 2) )
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PETITION FOR IMMEDIATE ACTION TO RELIEVE UNDUE RISK POSED BY THE INADEQUATE SEISMIC DESIGN OF THE PERRY NUCLEAR POWER PLANT
- 1. INTRODUCTION Pursuant to 10 CFR 2.206, the Ohio Citizens for Responsible Energy, Inc. ("OCRE") hereby petitions the Director, Office of Nuclear Reactor Regulation, to take immediate action to relieve undue risks to the public health and safety posed by the inadequacy of the seismic design of the Perry Nuclear Power Plant. OCRE reserves the right to reply to any and all responses to this petition which the Cleveland Electric Illuminating Company may submit and to have such replies considered by the Director before a decision is rendered on this Petition.
II. DESCRIPTION OF PETITIONER Petitioner OCRE is a private, nonprofit corporation organized under the laws of the State of Ohio. OCRE specializes in research and advocacy on issues of nuclear f.f&~hh$ f 1 EDO --- U03493 N
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16 reactor safety'and has as its goal the promotion and application of the highest standards of safety to such facilities. OCRE was an intervenor in the operating license proceeding for the Perry Nuclear Power Plant. Members of OCRE live and own property within 15 miles of Perry.
III. GROUNDS FOR RELIEF On January 31, 1986 an earthquake of magnitude 5.0 occurred with an epicenter about 10 miles south of the Perry Nuclear Power Plant. Concerned about the implications of seismicity in close proximity to PNPP, OCRE retained a ,
consultant, Dr. Yash P. Aggarwal, to research the matter. Dr.
Aggarwal's conclusions, presented in the Affidavit of Dr. Yash P. Aggarwal and associated report, "Seismicity and Tectonic Structure in Northeastern Ohio: Implications for Earthquake Hazard to the Perry Nuclear Power Plant", attached and incorporated herein as Appendix A, are that the January 1986 earthquake and historical seismicity can be associated with a tectonic structure revealed by magnetic data; that this fault, which probably passes within a few miles of PNPP, is capable of i
generating much larger earthquakes; that a magnitude 6.5 earthquake is a realistic possibility for the purposes of determining the proper Safe Shutdown Earthquake for Perry; and that the present SSE of mb = 5.3 + or - 0.5 does not provide the margin of safety required for nuclear power plants.
These conclusions reveal that FNPP is in a state of l
regulatory non-compliance, and, as such, poses an undue risk to i
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'dhe health and safety of the public. Specifically:
- 1. Licensees have failed to comply with the requirements of 10 CPR 100, Appendix A, Part IV, "Required Investigations", in that they have not identified and evaluated all' tectonic structures in the region surrounding the site (Part IV. (a) (2) ) ;
they have not correlated epicenters or locations of highest <
intensity of historically reported earthquakes with tectonic structures (Part IV. (a) (6) ) ; and they have not conducted a ,
reasonable investigation, using suitable geologic and geophysical techniques, of all faults in the region to
! determine whether they are to be considered as capable faults (Part IV. (a) (7)) .
- 2. Licensees have failed to comply with the requirements of 10 !
CFR 100, Appendix A, Part V, "Seismic and Geologic Design Bases", in that they have failed to evaluate the maximum earthquake potential associated with tectonic structures in the region, applying the procedures of Part V in a conservative manner, nor have they assumed that the epicenters of the earthquakes of greatest magnitude related to the tectonic structure are situated at the point on the structure closest to the site (Part V. (a) (1) ) ; and as a result, the present SSE for PNPP is insufficient.
- I j 3. Licensees have failed to comply with 10 CFR 50, Appendix A, i
l' General Design Criterion 2, "Design Bases for Protection l
l Against Natural Phenomena", and 10 CFR 100, Appendix A, Part 3
L 1
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VI, "Application to Engineering Design," in that they have not demonstrated that systems, structures, and components necessary
.to assure (i) the integrity of the reactor coolant ~ pressure boundary, (ii) the capability to shut down the reactor and maintain it in a safe condition, and (iii) the capability to prevent or mitigate the consequences cf accidents, including but not limited to the 8x8 fuel spacer (see Appendix B attached and incorporated horein), can withstand the vibratory ground motion resulting from a near-field magnitude 6.5 earthquake, including aftershocks and applicable concurrent functional and accident-induced loads, and remain functional at all stages of their design life.
- 4. Licensees have failed to comply with 10 CFR 50, Appendix A, General Design Criterion 2, "Design Bases for Protection Against Natural Phenomena", and 10 CPR 100, Appendix A, Part VI, "Application to Engineering Design," in that they have not demonstrated that systems, structures, and components necessary to assure (i) the integrity of the reactor coolant pressure boundary, (ii) the capability to shut down the reactor and maintain it in a safe condition, and (iii) the capability to prevent or mitigate the consequences of accidents, including but not limited to the 8x8 fuel spacer (see Appendix B attached and incorporated herein), can withstand the vibratory ground motion resulting from that earthquake which appropriate geologic and geophysical research, and conservative application of the procedures of Part V of 10 CFR 100 Appendix A, reveal to be the proper SSE, including aftershocks and applicable 4
c'oncurrent functional and accident-induced loads, and remain functional at all stages of their design life.
- 5. Licensees have failed to comply with the requirements of 10 CPR 100, Appendix A, Part V. (a) (2) in that the operating Basis Earthquake for PNPP is insufficient; licensees have not demonstrated that plant features necessary for continued operation without undue risk to the health and safety of the public can withstand the maximum vibratory ground motion which appropriate geologic and geophysical research, and conservative application of the procedures of Part V, reveal to be appropriately associated with the proper OBE, and remain functional at all stages of their design life.
IV. RELIEF REQUESTED Because this lack of compliance with the NRC's regulations raises substantial health and safety issues (see Northern Indiana Public Service Co. (Bailly Generating Station, Nuclear-1), CLI-78-7, 7 NRC 428, 433 (1978), _aff'd sub nom.
Porter County Chapter v. NRC, 606 P.2d 1363 (D.C. Cir. 1979),
the granting of relief is appropriate. OCRE requests that:
- 1. The operating license for Perry Unit 1 and the construction permit for Perry Unit 2 be suspend ' . .
- 2. Prior to reinstating the Ferry Unit 1 cperating license and the Perry Unit 2 construction permit: l Y
O
t
' =
(a) the Cleveland Electric Illuminating Company should be I
required to engage in appropriate geologic and geophysical )
l research, including but not limited to the recommended j confirmatory studies set forth at pp. 25-26 of the report "Seismicity and Tectonic Structure in Northeastern Ohio:'
Implications for Earthquake Hazard to the Perry Nuclear Power Plant", for the purpose of determining the appropriate SSE. In accordance with the recommendation therein, the unprocessed data from such research should be made available to disinterested insastigators; (b) CEI must evaluate whether applicable systems, structures, and components important to safety can withstand and remain functional, throughout their design lives, the vibratory ground motion (and concurrent normal and accident loads) resulting from (i) a near-field magnitude 6.5 earthquake; and (ii) the earthquake which appropriate geologic and geophysical research reveals to be the proper SSE for Perry. Should these systems, structures, and components, as built and installed in the l
plant, be unable to withstand either the magnitude 6.5 L earthquake or the appropriate SSE, corrective actions, including redesign and/or replacement, must be taken such that these seismic events can be withstood; 1
1 (c) In every other respect, CEI must take corrective actions to remedy all areas of noncompliance set forth in this petition; (d) a formal, public adjudicatory hearing should be held to i
determine whether the corrective actions taken are sufficient to achieve a level of safety that ensures that plant operation will not pose undue risk to the health and safety of the 6 .
- + ,
s.
< .. . i
,i' -.
public;-and (e) all changes found by the hearing board to be necessary to achi' eve that level of safety should be fully implemented at Perry Unit 1 and incorporated as conditions in the construction ,
permit of Unit 2.
- 3. Unless the conditions enumerated in paragraph 2. above are met, the operating license for Perry Unit 1 and the construction permit for Perry Unit 2 should be revoked.
Respectfully submitted, Susan L. Hiatt OCRE Representative 8275 Munson Road Mentor, OH 44060 (216) 255-3158 DATED: S' M 2 N
i i
7
- I
.g *. ?, '
l APPENDIX A UNITED STATES OF AMERICA NUCLEAR REGULATORY COMMISSION Before the Director, Of fice of Nuclear Reactor Regulation
)
In the matter of )
)
THE CLEVELAND ELECTRIC ) Docke t No . 50-440/441 ILLUMINATING CO. ET AL. ) 2.206 Petition
)
(Perry Nuclear power )
Plant, Units 1 and 2 )
)
AFFIDAVIT OF DR. YASH P. AGGARWAL STATE OF NEW YORK )
) ss.:
COUNTY OF kCNe4 I, YASH P. AGGARWAL, being duly sworn according to law, do hereby state the following as true:
- 1) I am president of Sensearth, Inc. Sensearth, Inc. is a corporation incorporated in the State of New York and engaged in the business of providing consulting services in the field of Geophysics, especially pertaining to earthquake hazard related problems. A statement of my professional qualifications is attached hereto as Exhibit A.
- 2) I am responsible for the preparation of the report ;
entitled "Seismicity and Tectonic Structure in Northeastern Ohio Implications for Earthquake Hazard to the Perry Nuclear Power Plant." This report is true and correct to the best of my knowledge and belief. ( Repo r t attached as Exhibit B and incorporated herein).
- 3) Based ,7on a recent review of seismological and geophysicai data for northeastern Ohio (as documented in the above-mentioned report) , it is my profcesional opinion that an earthquake of magnitude 6.5 of larger is probable in the vicinity of the Perry Nuclear Power Plant.
- 4) The design basis of the Perry Nuclear Power Plant is a magnitude 5.3 + or - 0.5 or a Modified Mercali Intensity VII .
earthquake. Given my findings, it is my prof essional opinion
4 4
4 =g 1-
, s' that the Safe Shutdown Earthquake for PNPP should be substantially larger than the design earthquake used for PNPP.
- 5) Affiant f urther sayeth naught.
Dated: [,[1,/f 7 "d%%f d __,
Yash P. Agg arwal Sworn to and subscribed before me, Public, on this 9_ day of ' Ju. AL _ _, 1987, ata Notary
')A & t' //i'Z f _,
New York. p
- l l
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h M N E,Y @i [I.
NOTAftY-PU BLIC' c
l JL 011H C0rtMLEY NQiAhr /JcuG. inn a N r.v i sg
.d 4730539 Quthhe3 n Rxkiv DJ N Me&Id;O I-QJte ( ~ , ' , N f f 1
i
- f,* ,. EXHIBIT A YASH PAL AGGARWAL
, CURRICU M VITAE Business Address .
SENSEARTH Inc., 17 Tarry Hill Drive, New City, N.Y. 10956 (914) 6341980
.PosiEioni2 President Home Address i
2 Rookery Circle, New City, N.Y. 10956 Education f.q, Ph.D. Seiscology, Columbia University, 1975 H.Sc. Geo; sical Engineering, Institut de Physique du Globe oourg, France, 1970 B.Sc. University of Strasbourg, France, 1966
( Math. & Physics Major)
B.Sc. Fqrgusson College, University of Poona, India, 1962 (Physics Major)
Awards and'Scholarshics UNESCO support to study the Rift Valley in Kenya, 1970
'b.ich Government Scholar ip, 1964-1970 Best student award, Nairobi, K.inya, 1958 Professional Activities _
Membec American Geophysical Union Expert witness and consultant to the State of New York on earthquake related problems, 1976-1977 Consultant to the Govt. of Venezuela, earthquake hazard to large engineering projects, 1980-1985 Consultant to the Town of Ciskstown, N.Y., on Quarry blasts related problems, 1985 b
=_ p __
'.'3*
/ASil PAL-AGCARWAL PUBLICATIONS 1971 .Microcacthquakes and the Rift Valley in Kenya (Haster's Thesis, in Frer.ch), Univesity of Strasbourg, France, 1-57 pp.
1971 A microearthquake survey in Kenya, wi r.h P. Molnar, Bull.
Seismol. Soc. Am., S , no. 1, 195-201.
1972 P and S traval times in the Tonga-Fiji region: A zone of low velocity in the uppermost mantle behind the'Tonga Island arc, with B. Huawia and B. Isacks, J. Geophys. Res., E , no. 2.
6427-6434.
1972 New esults in the field of earthquake prediction, Proceedings of the Eleventh Annual Conference on Recent Advances in Physics, Chapc1 Hill, 59-63:
1972 The Adirondacks, New York, earthquake s wa rm of 1971 and tectonic implic a t ion s , with M. L. Sbar and J. Armbruster, Bull. Seismol. Soc. Am., 6 2,, no. 5, 1303-1317.
1973 Premonitory changes in seismic velocities and prediction of earthquakes, wi t h L. R. Sykes, J. Armbruster end H. L. Sbar, Nature, 241, 101-104.
1973 Earthquake prediction: A physical basis, with C. H. Scholz and L. R. Sykes, Science, 181, 803-810.
1974 Can we predict earthquakes, Science Today, 13-17. A Times of India Publication, Bombay, India, February 1974.
1975 Spatial and temporal variations in t 0/ t,, and in P-vave residuals at Blue Fountain Lake, Ne w York: Application to earthquake prediction, with L. R. Sykes, D. Sicpson and P. G.
Richards, J. Geophys. Res., 80, no. 5, 718-732.j 1975 Earthquake prediction: Dilatancy-fluid diffusion mechani,sm of earthquake precursurs (review paper), Encyclopedia
, Universalis, Paris, France (in French) .
1977 Testimony on behalf of the State of New York, before the Atomic Safety and Licensing Appeal Board, NRC, concerning Indian Point Units, 1, 2, and 3, filed February 25, 1977.
1978 Earthquakes, laults and nuclear power plants in southeastern New York-northern New Jersey, with L. R. Sykes, Science, 200, 425-42).
1980 Seismicity and tectonics of Philippine Islands, with H. K.
Acharya, J. Geophys. Res., g , 3239-3250.
. . , s ., *.
'.',- i' YASH . PAL AGGARWAL PUBLICATIONS 1981 Se ismo a.e c t onic s of northeastern North America and adjacent Canada, with J.-P. Yang, J. Geophys. Res., 86,, 4981.
1981 Present-day tectonics of the southeastern Caribbean and north-ern Venezuela, with 0. Perez, J. Geophys. Res., 86,, 10791.
1981 Investigaciones sismologicas en el occidente de Venezuela. para las consideraciones sismicas en el Proyecto Uribante-Caparao, FUNVISIS, Caracas, Nov. 1981, pp. 1-14.
1982 Si smo s,. locales registrados por la Red Sismologica de Uribante-Caparo: Implicaciones para el diseno antisismico de las presas y las probabilidades de sismicidad inducida, FUNVISIS, Caracas, Marzo, 1982.
1984 Actividad seismica en la region de Uribante-Caparo, Enero 1983 - Marzo 1984, FUNVISIS , Carac a s , Mayo 1984.
1984 Act.ividad sismica en la region de Urib a r.t e-Ca pa ro , Abril -
Augusto 1984, FUNVISIS, Caracas, Oct. 1984.
1984 Long-term seismic behavior of the focal and adjacent regions of great earthquakes during two successive shocks, with 0. -
Perez and C. Scholz, J. Geophys. Res., in press .
1985 Ground vibrations and airblasts generated by blasting at Trap Roe.K Quarry: Seis.clogical, Legal, and Health and Safety Aspects.
Report to the Town Board, Town of Clarkstown, Rockland Co., N.Y.
.)
4
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.v
EXHIBIT L l
SEISMICITY AND TECTONIC STRUCTURE IN NORTHEASTERN OHIO:
IMPLICATIONS FOR EARTHQUAKE HAZARD TO THE PERRY NUCLEAR POWER PLANT A Report to the Ohio Citizens for Responsible Energy, Inc.
l Prepared by YASH P. AGGARWAL Sensearth, Inc.
March 1987
- ----- -T-'W-'C- Y'
1 se r a s({'{A<o, s ,xs. a 'ils,..i,,rac e i.e~u,.,
g a o~,vi 17 i AMY Hitt OM/t. P.CW Cit'Y N Y 10956 (014)634 1060 l
l SEISMICITY AND TECTONIC STRUCTURE IN NORTHEASTERN OHIO:
IMPLICATIONS FOR EARTHQUAKE HAZARD TO THE PERRY NUCLEAR POWER PLANT f
YASH P. AGGARWAL r.oren .n7
(
l
- . - . _ . . . - . - _ _ _ . . . , . _ __.._._-..m,__.___.._-.,._____-.___.-_.,___..__.._.._...__--___.____.._.._4... -
~ . - - .
1 l
TABLE OF CONTENTS Executive Summary . . . . . . . . . . . ............ 1 Introd u ctio n . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 The 1986 Earthquake . . . . . . . . . . . . . . . . . . . . . . . 4 Af tershock Data Base Source Characteristics Mainshock Magnitude Structural Relationship . . . . . . . . . . . . . . . . . . . . 14 Historical Seismicity Correlations Im plica tion s . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 4 Recommendations . . . . . . . . . . . . . . . . . . . . ... 27 Notes and Acknowledgments . . . . . . . . . . . . . . . 27 References............... .... ........ 28
' } ;. ' '
EXECUTIVE
SUMMARY
At the request of the Ohio Citizens for Responsible Energy, we critically re'/:2;;ed recent studies concerning the January I1,1986 and other h!storically recorded eartnquakes in northeastern Ohio having a oearing on the design basis for the Perry Nuclear Power Plant. This report discusses the results of this effort, shedding new light into the source of the January 31,1986 earthquake and the probable relationship of this (magnitude 5.0 mb) and several other small to moderate size earthauakes to tectronic structure in northeastern Ohio. '
Hypocentral locations and focal mechanism 5011 'qs for thelarger aftershocks of the January 31,1986 event define a near vertical . lateral strike slip fault trending ap-proximately N30cE: a result consistent with tne. Acal mechanism solution for the main-shock. The rupture area associated with the 1986 event is inferred to be about 2 to 4 km2, centered at a depth of about 6 km, Apparently, surficial geologic data do not reveal the trace of such a fault In the epicen-tral area of the 1986 earthquake. Nevertheless, magnetic anomaly data for northeastern Ohio show a prominent magnetic boundary (Akron Magnetic Boundary), the location and the general trend of which agree remarkably well with the fault inferred from earthquake data.
Furthermore, we observe that the bett':r lcated (epicentral uncertainty 510 miles)
"macroearthquakes" of MM Intensity '2 IV, known to have occurred historically within 50 miles of the 1986 event, show a non random distribution falling on or close to the Akron Magnetic Boundary.
These correlations strongly suggest that the Akron Magnetic Boundary in north-eastern Ohio marks the locus of a pre existing fault or fault Zone. The spatial extent of the correlated epicenters indicates that the active portion of this fault zone is at least 70 km in length and probably about 10 km in width down dip. Consequently,in our opinion, this fault must be considered capable of generating an earthquake much large than the magnitude 5.0 earthauake of Januar! 31,1986.
1
Theoretically, the inferred fault area available for rupture is large enough to accom-modate a magnitude 7 or even larger earthquake. Conservatively, however, the occu -
rence of a magnitude 6.5 earthquake is in our opinion a realistic possibility for the pur-poses of determining a design basis earthquake for the Perry Nuclear Power Plant (PNPP).
Cleally,in light of these new findings, the design earthquake of MM intensity Vil or mb 5.3 i 0.5 adopted for PNPP oli the basis of previous studies does not provide the margin of safety required for nuclear power plants. Unfortunately, this view is further strengthened by an Indication in the data that the inferred fault (zone) probably passes within a few miles of the power plant site; which potentially places PNPP within the near -
field of a strong earthquake generated by this fault.
o 2
INTRODUCTION On January 31,1986 an earthquake of magnitude 5.0 (NEIS) occurred in northeastern Ohio, about 18 km south of the Perry Nuclear Power Plant. This was the largest earth-Quake known to have occurred in the northeast Ohio region during historical timer, The earthquake was widely felt, causing panic, minor injuries, and some damage ap-proaching intensity Vil on the Modified Mercall (MM) intensity Sca!e (U.S. Geological Survey,19861. Both the U.S. Geological Survey (USGS) and Weston Geophysical Corpora-tion (WGC), who conducted intensity surveys, assigned an epicentral MM Intensity VI to the shock.
A rapid deployment of portable selsmographs by several Institutions or agencies resulted in the acquisition of data for 13 af tershocks ranging in magnitude from -0.5 to 2.5, of which two were felt (see e.g. USGS,1986). Af ter a compilation of the data acquired by the participating institutions. the U.S. Geological Survey and Weston Geophysical Cor-poration Independently determined source parameters for the af tershocks, including hypotentrallocations and focal mechanism solutions. The results were published in two separate reports lUSGS,1986; WGC,1986), that also discussed historical seismicity and at-tempted to tackle, among other issues, the significance of the 1986 shock and its rela-tionship to tectonic structure.
Based on the mainshock-af tershock data, the U.S. Geological Survey did not reach any definitive conclusions as to the orientation of the fault responsible for the 1986 event; whereas Weston Geophysical Corporation concluded that the earthquake occurred on a near vertical, strike slip fault trending NNE. The two studies, however, concurred that there was no obvious tectonic structure with which the 1986 event could be reasonably correlated. The USGS report, nevertheless, recommended additional geophysical in-vestigations to understand the structural and tectonic conditions that led to the 1986 earthquake.
The licensing basis for PNPP was established prior to the occt'rrence of the 1986 shock, placing PNPP within the Central Stable Province with a design earthquake of MM Intensi-ty Vil or mb 5.3 i 0.5 (see e.g., WGC,1986). Concerned about the implications of the 1986 event on the level of seismic hazard for PNPP, the Ohio Citizens for Responsible Energy (OCRE) sought our professional opinion and made available to us the reports cited earlier along with some additional material.
3
O Reviewing these reports, certain observations that had apparently been overlooked or missed began to emerge, which prompted us to thoroughly reappraise the data con-tained therein hoping to clarify some of the issues raised by the occurrence of the 1986 event. First, we realized the need to separate the data from the "noise"(so to speak) that nay have needlessly masked or rendered ambiguous an otherwise clear result. Con-sequently, we consistently scught to extricate, for example, from the available seismici-ty data the more valuable events using such objective criteria as earthquake size and location uncertainty, and relled primarily on such data in reaching conclusions. Second-ty, we derived new composite focal mechanism solutions for the af tershocks of the 1986 event based on the P wave first motion data reported in these studies. We did not, ,
however, seek or attempt to reanalize the primary source (e.g. selsmograms, Intensity reports) of the data contained therein. The results that follow are aimost entirely based on the data compileo or obtained by previous workers. Primarily, our contribution is some important new observations and conclusions based thereupon.
First, we discuss the results of the 1986 mainshock-aftershock sequence of events, clarifying the nature of the source of the mainshock. Later, we discuss the correlation of the 1986 shock and the larger historical earthquakes to tectonic structure in the area, and its implications for earthquake hazard to PNPP.
THE 1986 EARTHQUAKE Aftershock Data Base As of April 15,1986, thirteen aftershocks were recorded by a portable network of seismograpns deployed by a number of institutions or agencies soon after the occur-rence of the mainshock on January 31,1986. The phase data compiled from the analysis of seismograms by the participating Institutions, and the resulting source parameters for these af tershocks determined by the U.S. Geological Survey and Weston Geophysical Corporation (WGC) are tabulated in their respective reports (USGS,1986; WCC,1986).
An examination of the source data (e.g. Table 3, USGS,19861 shows that the af tershocks can be separated into two distinct groups based on their size and displaying different temporal characteristics. First, we note that 7 of the 13 af tershocks had magnitudes 2 0.8 (0.8 to 2.4), whereas the remaining 6 were much smaller in size (magnitude -0.5 to 0.1), by almost 2 units of magnitude On the average. It is equally noteworthy that all but 4
One of the larger af tershocks occurred within the first 10 to 11 days following the main-shock, whereas all but one of the smaller af tershocks occurred much later in time, i.e. cin or after the 23rd day following the mainshock. Furthermore, as expected, the phase data for the larger af tershocks are in general more abundant and reliable than for the smalle: Shocks, resulting in overall better determined hypocentral locations and focal mechanism solut!ons (see e.g., USGS,19861.
The aftershock locations obtained by the USGS and WGC using various velocity models differ little, excepting the focal depth determination that shows some dependence on the velocity model chosen. For the purposes of this report, we chose to use the hypocentral locations preferred by the USGS and obtained using a velocity model that attempts to take into account the structural complexity of the area. Table 1 (this study) lists the preferred locations for the 7 larger af tershocks determined by the USGS. The events are numbered in chronological sequence in Table 1.
For these larger af tershocks we determined composite or Individual focal mechanism solutions, combining events 1,3,4 and 7 (magnitude 21.3)into one group, events 5 and 6 (magnitude = 1) into another, and event 2 (the smallest) all by itself. The P wave first motions reported in the USGS and WGC studies were used for this purpose, excepting a small number of arrivals that were indicated as emergent. The inclusion of these less reliabl? data does not, however, affect the focal mechanism solutions.
Figure 1 shows the hypocentral locations of the 7 aftershocks. The events are numbered in chrorMiogical sequence, and a differen'. ymbolis used for each group of events for which a focal mechanism solution was determined. The focal mechanism solu-tions are shown in Figures 2, 3 and 4. The star in Figure 1a Indicates the location (41.650cN,81.162%V) of the mainshock obtained by the USGS, holding the focal depth fixed at 10 km.
Source Characteristics Long period surface wave data Indicate that the mainshock occurred at a shallow depth (2 to 6 km), either on a right lateral strike slip fault trending approximately N28CE and dipping steeply (2822) to the wast, or on a lef t lateral strike slip fault trending N115CE and dipping about 700 to the south (Hermann and Nguyen.1986).
f The epicentral distribution of the af tershocks (Figure ia) shows a rather clear north-northeasterly alignment, in agreement with the orientation of one of the nodal planes determined by Hermann and Nguyen (19861 for tha mainshock. Also,in each of the three 5
7 Table I Larger Aftershocks of 1986 Earthquake (USGS,19861 Event Latitude Longitude Date Depth ERH ERZ Mag.
No. Mo Day Deg Min Deg Min km km km 1 02 01 41N38.82 81W9.42 4.97 0.45 0.80 1.4 2 02-02 41N38.75 81W9.53 4.99 0.25 0.23 0.8 3 02-03 41N38.90 81W9.61 6.93 0.26 0.36 1.8 4 02 06 41N38.57 81W9.64 5.89 0.28 0.41 2.4 5 02-07 41N39.06 81W9.25 4.64 0.29 0.22 1.1 6 02 10 41N39.16 81W9.27 4.97 0.29 0.42 0.9
__. 7 03 24 41N38.05 81W9.97 4.92 0.45 0.40 1.3 6
1
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. _J l I 61 IO'W elog' Fig.13 - Epicentral locations IUSGS,19861 for the 1986 mainshock (star) and 7 largest af tershocks numbered in chron'ological sequence as in Table 1. For each group of af tershocks denoted by a Common Symbol, a focal mechanism solution was determined (Figs. 2,3, and 41. The strike (N30cEl of one of tne nodal planes in Fig. 2 is shown.
7
W30 Ne + E 30 S l l \
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25 I
H 0.
to O
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-0.5km 0.5km Fig.1b - Vertical Cross section showing the focal death distribution of the af tershcCks on a plane perpendicular to N30cE. the trend observed in (a). Note that the earthquake foci show a near-vertical distribution Consistent with the dio of the N30"E striking nodal Diane in Fig. 2.
8
S 30 W +-- -+ N 30 E I I I 5
mm7 nel 5 -
pF O -
T 5 mm4 I 6 -
H 0.
to o
as 7 - = -
3 IN-PLANE PROJECTION E-M > 1 Oe-M 41 8 ! I
-I km O Ikm l
Fig.1C - Vertical cross section showing the focal depth distribution of af tershocks on a plane strik-Ing N30cE. parallel to the trend observed in fa). Note that the focal depth (2 to 6 km) of the mainshock (not plotted)is Consistent With the d?pth distribution of the af tershocks.
i l
l 9 l
l L _
focal mechanism solutions for the aftershocks (Figures 2,3 and 4) one of the nodal planes trends NNE (N15cE to N32oE), although its d!p varies considerably.
It is remarkable that the composite focal mechanism solution (Figure 2) for the four largest af tershocks (Squares, Figure 1) is almost identical to the focal mechanism solution for the mainshock. Both the strike and the dip of the NNE trending plane in Figure 2 are in excellent agreement with that determined by Hermann and Nguyen (1986) for the mainshock using surface wave data. The composite focal mechanirm solution (Figure 3) for the next two largest af tershocks (events 5 and 6, Figure 1) is also essentially similar to that of the mainshock. Only the smallest (event 2, Figure 1) of the 7 af tershocks ap-parently shows a substantially different focal mechanism solution (Figure 4). Note, however, that in this case also one of the nodal planes trends NNE.
Figures 1b and 1c show the focal depths of the aftershocks projected on vertical planes orthogonal and parallel to N300E, the strike of one of the nodal planes in Figure 2.
The orthogonal projection (Figure ib) shows a near vertical distribution, in excellent agreement with the dip of the NNE Striking nodal plane in Figure 2, the focal mechanism solution closest to that of the mainshock. The parallel projection (Figure 1c),in contrast, shows a rather random distribution.
The above results leave little doubt that the mainshock occurred on a near vertical fault trending NNE. Tne sense of motion is deduced to be right lateralstrike slip. The rup-ture area associated with the mainshock is Inferred from the in plane projection (Figure 1c) to be about 2 to 4 km2, depending on whether one choo.ies to evclude or include event number 7 that appears to be somewhat isolated from the rest of the af tershocks.
In either case we conclude that the fault (as opposed to the rupture zone) responsible for the 1986 event is at least 2 km long, as indicated by the epicentral distribution of the af tershocks (Figure 1a) having similar focal mechanism solutions (Figures 2 and 3).
The observation that event number 2 apparently shows a thrust mechanism (Figure 4),
in contrast to the strike slip mechanisms for the other aftershocks (Figures 2 and 3), is not surprising. Its location (Figure 1), and the fact that one of the nodal planes trends NNE (Figure 4), suggest that this event probably also occurred on the same fault as the other aftershocks. A fault p!ane is not expected to be a smooth surface, and such small events are likely to occur on slight "bumps" on the fault surface where stresses may con-centrate af ter a sizeable earthquake. More importantly, however, the focal mechanism solution for the mainshock as well as its af tershocks Indicate that these events occurred in response to a stress system in which the maximum principal stress axis is nearly horizontal and oriented ENE.
l l
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FOCAL MECHANISM, EVENTS 1,3,4,7 LOWER HEMISPHERE PLOT
- -COMPRESSION P-AXIS, N66 E O- DILATATION T-AXIS, Nf 67 E -
Fig. 2 - Composite focal mechanism solution for the fourlargest af tershocks of the 1986 event. The
! event numbers CorresDond to those in Fig.1 and Table 1. The strike and the diD of the nodal l Plane inferred to be the fault plane are indicated. P and T respectively denote the Pressure and Tension axes.
l 11 L
0 9 N
, v N15E 62 WNW e
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, J FOCAL MECHANISM, EVENTS 5,6 LOWER HEMISPHERE PLOT e-COMPRESSION P- AXIS, N52 E O-DlL ATA rlON T-AXIS, NI48 E Fig.3 - Composite focal mechanism solution for events 5 and 6 (FiJ.1. Table 1), af tershocks of the 1986 event. Symbols as in Fig. 2.
12
N I
s 4 N32 E N, 40 WNW
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FOCAL MECHANISM, EVENT 2 LOWER HEMISPHERE PLOT O-COMPRESSION P- AXIS, N 97 E O-DILATATION Fig.4 - Focal mechanism solution for event 2 IFig.1, Table 1), the smallest of the 7 largest af ter-
$h0Cks Of the 1986 earthquake. The solution is not Well constrained. SymDols as in Fig. 2.
13
~
Mainshock Magnitude The National Earthquake information Service (NElS) calculated the magnitude (mb) for the 1986 event using telesismic P wave arrivals at 16 stations. The Individual mb values range from 4.1 to 5.9, yielding an average value of 5.0 (5.03) for the 16 readings. Initially, NEls had assigned a preliminary mb value of 4.9 based on readings from 10 stations.
The Earth Physics Branch (EPB) of Energy, Mines and Resources Canada obtained mbLg values for 24 stations in the Canadian Network. These data are tabulated (Appendix A3.2)
In the WCC report (1986). Figure 5 shows the mbLg (Mn) obtained from the Canadian Net-work as a function of station azimuth. A remarkably clear dependence of mblg on azimuth emerges from this plot. The peak near N30oE is rather well defined and is in ex-cellent agreement with the focal mechanism solution of the mainshock, from which one would expect maximum aptitudes for Lg waves at stations located along the strike (NNE) of the fault plane responsible for the 1986 event.
The individual values for mbLg range from 4.9 to 5.7, and the average value is 5.3 (5.28).
The dif ference between the mb magnitude (5.0) and the mbLg magnitude (5.3)is not sur-prising in light of the azimuthal dependence of mbLg observed here. The higher mbLg magnitude is attributed to the fact that almost a half of the Canadian stations reporting mbLg values lie within about 200 of the strike of the fault plane responsible for the 1986 event (Figure 5), thus resulting in near maximum amplitudes for Lg waves recorded at these stations.
STRUCTURAL RELATIONSHIP Historical Seismicity Apart from the 1986 sequence of events, som2 25 earthquakes, apparently located within approximately 50 miles of PNPP, have ocsurred in the northeast Ohio region since 1823 ITable 3 2, WGC,1986). Most of thesa events are, poorly located and as such are of lit-tie use in understanding the relationship of seismicity to tectonic structure in the area.
l Among the larger (MM intensity 2 IV, or magnitude 2 3) events, however, there are several that are relatively welllocated (uncertainty 510 miles) according to the data compiled by Weston Geophysical (1979,1986). The epicentrallocations of these events along with that of the 1986 mainshock are shown in Figure 6. We discuss these events briefly in their chronological sequence going backward in time.
14 l
l l
1, f, . _ ., -
6 W N E i l t
, r X
/ \
X XX
/ \
? 5.5 -
j* XX X -
E /
to o / \w\
X o / \ -
b # x\
z /
O 4
A / h.
\ \
2 5 -
NX X/ *< -
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X X 4.5 I l 1
-10 0* -50* O' 50' 10 0' AZIMUTH Fig. 5 - Plot Showing magnitude (mt,Lg or Mnl determinations f or the 1986 ma;nsnock as a functio.1 Of Station azimuth for the Canadian Network obtained by the Earth Physics Branch. The curve Shows an aDoroxiniate fit to the data. The arrow indicates the strike (N30'El of the fault plane inferred fcr the 1986 event; note the peak at Or near this azimuth.
I 15
The 1983 event that occurred on January 22 was recently relocated by Weston Geophysical using instrumental data In addition to those used initially by NEls and ISC (In-ternational Seismological Centre) or EPB. The epicenter was relocated at 41.765eN, 81.1100W with an estimated uncertainty of about 3 km IWGC,19861. This event was not felt. NElS assigned a magnitude 2.7 mbLg to this event, whereas EPB (Ottowal obtained a value of 3.3. In each case, the magnitude is based on readings from only a few stations.
Hence, in our opinion, an average of the two determinations (3.01is a better measure of the magnitude of this event than any one of the two values.
The 1943 event was recently relocated by J. Dewey (USGS,19861 using instrumental data. Its revised location (41.6280N i 14 km,81.3090W i 10 km) is essentially similar to that (41.60N,81.30W', listed by Coffman and von Hake (19731. This event was widely felt and Weston Geophysical assigned an MM intensity V to it. Its instrumentally determined ~
magnitude of 1.7 mbLg is identical to that estimated from the felt area Isee, WGC,1979).
Two events 1ccurred in 1955, one on May 26 and another on June 29. Both of these events were relocated at 41.33CN,81.400W by Weston Geophysical on the basis of the distribution of felt reports compiled and analyzed by WGC (1979). Seismograms for these events from John Caroll University station (Fig. 6), however, provide Instrumental con-trol on tM epicentrallocations.Weston Geophysical (19791 noted that the locations are in good agreement with the epicentral distance (~ 20 km) and azimuth (southeast of John Carroll) estimated by Dr. E. Walter from seismograms (see also Fig.6). This agree-ment suggests that the epicentral uncertainties are probably (.~ 10 km) somewhat less than those (10 miles) assigned by Weston Geophysical on the basis of intensity data alone. Weston Geophysicall1979,1986) assigred an MM intensity IV V to the May 26 event and intensity IV to the June 29 shock, and lists a magnitude (mbLg) 3.6 for both events. A check of the short period selsmograms at the Lamont Doherty Geological Observator/
revealed that both shocks were recorded at Palisades, N.Y.; which suggests that perhaps some other stations in North America may also have recorded this event. We did not, however, make an effort to obtain any such data.
The Dec. 3,1951 (MM intenalty IV, mbLg 3.2) was located (41.600W. 81.40%) by Weston Geophysical (1979,19861 on the oasis of felt reports, with an estimated uncertainty of 5 miles. The event was felt in an area less than 10 miles in radius around Willoughby, and was recorded on a 3 component short period station operated by John Carroll Universt-16
, ~.
l, .y ty (WGC 1979). The seismograms indicate an epicentral distance of about 30 km IWGC, 1979), whereas the epicentral distance from the WGC location is only about 15 km (See Figure 6).This discrepancy, combined with the observation that the shock was apparent-ly not felt at Painesville or in Cleveland (Figure 6), suggests that the epicenter should be approximately 15 to 20 km ESE of the WGC location or possibly to the NW of Willoughby in Lake Erie, Consequently, in our Judgement the WGC location is in error or uncertain by 10 miles or more.
In view of the fact that for events occurring relatively close to Lake Erie sollampilfication effects and population density distribution would tend to bias (towards the lake) epicen-trallocations based solely on felt reports, it is not surprising that the WGC location for the 1951 event is not in accord with the instrumental data. In contrast, it is noteworthy that the WGC locations for the 1955 events discussed earlier are in good agreement with -
Instrumental data; which suggests that for events occurring relatively far from Lake Erie their locations are not significantly affected by soll amplification or population concen-tration along Lake Erie's south shore.
Lastly, two events occurred near Akron about 85 km SSW of PNPP (Figure 6). The 1932 event (MM intensity IV) that occurred on Jan 21 was felt only on the west shore of Lake Summit situated within the city limits of Akron (WGC,1979). Accordingly, Weston Geophysical assigned to its epicenter the coordinates (41.080N,81.500W) of the lake as determined by Docekal (see WGC,1979), and later adopted the epicenter (41.10cN, 81.600W) obtained by EPB Isee Table 3 2, WGC,1986). The two locations are similar, and the relatively small difference appears to be due to rounding off errors in the Coordinates (41.06CN, 81.55cW) of the lake. Weston Geophysical (1979) dia not assign an epicentral uncertainly to this event. Judging from the observation that the event was apparently felt in a rather localized area within an urban environment. It is our opinion that the uncertainty in the epicentral location (41.06cN,81.550W) is probaoly 10 km or less.
Weston Geophysical ists another earthquake on Jan. 22,1932 (magnitude 3.6) at essen-tlally the same location (41.100N,81.500W) as that on Jan. 21,1932 referring to Nuttil as the source (see Table 3 2,'VGC,1986), but does not mention this event in its 1979 report.
It is not clear whether the two events are one and the same earthquake with a possible error in the date in one of the catalogs, or two separate events one of which might have been initially missed by WGC in its 1979 catalog. In Figure 6, however, we have plotted 17 l
,e ,.
42 0 815'l R1'V/l 47 on PNPP LAKE ERIE Painesville 1933 O
Willougn0y 1936 h1943 y1951 41 3 O ES' -
clevelana John carron k 1955 (2)
O Aurora Akron 1885 10 9
C km h1932 41cN 815'l BWal Fig. 6 - Map of Northeas, tern Ohio showing the epicenters (WGC, 1979,1986; USGS,19861 of local earthquakes (within 50 miles of PNPP) of MM intensity 2 IV or mag. 2 3, located with an ancer-tainty 510 miles excepting the 1951 event (see text). Note the rather clear NNE trend in eclCenters.
18
.c .-
Only cne event using the coordinates of Summit Lake as its epicenter, and have assigned to it an uncertainty of 10 km.
The other event near Akron (Figure 6) occurred on January 18,1885. This event (MM in-tensity IV) was reiccated by Weston Geophysical!19791 on the basis of the distribution of felt reports. The WGC location (41.100N,81.450W) is similar to that (41.10eN,81.40oW) listed in the EPRI catalog with an epicentral intensity MM IV and magnitude 3.8 (see Table 31, WGC,19861. The epicentral uncertainty of 10 miles estimated by Weston Geophysical appears to be adequate, although the distributions of felt reports suggests that the epicenter shou;d be somewhat to the west or NW of the WGC epicenter plotted in Fig. 6 (see WGC,1979).
All of the "lCcal" earthquakes discussed above occurred during the past 100 years (1885 1986). During this time period there were possibly two additional local shocks (Sept. 29,1928; Oct. 29,1934) of MM intensity 2 IV, both of which are not used in this study. Not only is the location of the 1928 event poorly known, but also its nature (earth-quake?) remains a mystery (WGC,1979). The 1934 earthquake (MM V) was located (42.0cN, 80.20W) by WGC (1979) at or near Erie, Pennsylvania, on the bas ls of felt reports from Erle obtained from newspapers in northeastern Ohio. The uncertainty in the location of this event is, however, unknown or difficult to estimate in the' absence of felt reports from sources in Pennsylvania. Similarly, the locations of four much older (1836,1850,1857, and 1858) local earthquakes of MM 2 IV are in general poorly constrained (see WGC,1979), and hence these events are also not used here.
Correlations The epicentral distribution of earthquakes in Figure 6 shows a rather strong NNE trend or alignment. Clearly, the uncertainties in individual locations (516 km except for the 1951 event) discussed earlier are much smaller than the lateral extent (about 80 km) of the eplcenters defining a NNE trend. Secondly, the distribution of population in north-eastern Ohio does not exhibit a particular pattern that could reasonably be correlated with the trend observed in earthquake epicenters. Also, note that all but one (1951) of the events are either instrumentally located (1943,1983,1986) or occurred relatively far from Lake Erie (1885,1932, and 2 in 1955). Consequently, biases resulting from soll ampilfication effects or population density along the lake shore cannot be invoked to either assign larger uncertainties to the locations or explain the trend in the epicentral 19 i
~-
y
- l. .
)
- i .
n locations. Furthermore, these events are among the largest earthquakes known to have occurred in northeastern Ohio. We conclude that the NNE trend observed in the epicen-trallocations is not simply fortuitous, but represents an important if not a fundamental characteristic of the seismicity in this region.
in Figure 7 the epicenters of the better located events (uncertainty 516 km) are superimposed on a magnetic anomaly map of northeastern Ohio region compiled by Hildenbrand and Kucks (1984). Note that the 1951 event (Figure 6) which is less well located, as discussed earlier,is not plotted in Figure 7. The shaded area indicates the ap-proximate location and the general trend of the northeastern Ohio section of a proml-nent magnetic boundary (Akron Magnetic Boundary) that separates an area of relatively smooth magnetic anomalies to the east from the region of rapidly varying magnetic anomalies to the west.
In Figure 7 we observe that the NNE trend in earthquake epicenters corresponds rather well with the general trend (NNE) of the magnetic boundary. Also, we note that the earthquake epicenters are located on or close to the magnetic boundary, and within the uncertainties of the data the earthquake epicenters correlate well with the location of the boundary.
This correlation is particularly clear where the data are the most precise. For example, in the case of the 1986 event the strike (::'N300E) of its fault plane, inferred earlier from seismological data,is almost identical to the trend of the Akron Magnetic Boundaryjust south of the epicenter where the boundary trend is particularly well defined (Figure 7).
Also, the epicenter of this event having a probable uncertainty of only about i Km (WGC, 1986, also Figure 1al is essentially located on the magnetic boundary (within the uncer-tainties inherent in the demarcation of the boundary). We note that the correlation of the 1986 event with this magnetic boundary was also observed by Seeber (1986).
The next best located event is perhaps the 1983 Uanuary 22) earthquake that was recently relocated by Weston Geophysical (1986) with an uncertainty c' Wout 3 km using instrumental data. Figure 8 shows the location of this event in relation to that of the 1986 shock. The box denotes the epicenter of the 1983 event obtained by Weston Geophysical (19861 by averaging the various epicenters (crosses) computed with dif-ferent velocity models and/or different weighting schemes. Figure 8 shows that the epicenter of the 1983 shock is located essentially on strike of the fault plane for the 1986 event some 13 km north of the later. Unfortunately, the P wave first motions for the 1983 earthquake recorded at several stations (see seismograms, WGC,1986) are not clear 20 i
, *82d .
81cw 42.00 (2) mW_ _
e u ,
y; /
-200 N O 10 u I wo g l<o.,
o n y i
+--
41cN ua
- 6 ses Fig. 7 - Residual total niagnetic mao of northeastern Ohio region (Hildenbrand and Kucks.19841.
Epicenters (WCC, 1979,1986, USGS,1986) cf the better located (uncertainty 516 km) local earthquakes (within 50 miles of PNPP) of MM Intensity 2 IV or mag. 2 3 are superimposed on the magnellC m3D. The strike of the fault Diane and the sense of motion on it for the 1986 shock are shown. The shaded area shows the approximate location of the magnetic boundary observed in the data. Note that the epicenters are located on or close to this coundary 21 '
I i 1
N PNPP
- I N N30 E - 41.8' N
/
/
xx /
X j i ? /
/
1983 lx
% } b x
/
/
/
/
/
/
_ /
/
41.7'
/
/
/
/
/
1986 d
/
/ O 2 4km j MJ !
/
I I
41.6*
8 .2'W 81.I' Fig. 8
- Map showing the location of the January 22,1983 event (WCC.1986lin relation to that of the 1986 earthauake and its focal mechanism. Crosses Indkate individual location; of the 1983 eventoP' ined using different velocity models and/or weighting schemec and the box in-dicates ti.e average of these solutions with its uncertainty (bars) adopted by Weston as tne epicenter of the 1983 event. Note that the 1983 event lies essentially on strike (broken line) of tht.1986 fault Diane.
22
enough to determine whather or not the first motions are consistent with the right-lateral strike stip motion determined for the 1986 event.
, . It is also noteworzhy that the epicenters of the two earthquakes in 1955, although less well constrained ( 10 km), are apparently located on the magnetic boundary. Since these ev 1ts were recorded by the John Carroll station, the epicentral distances ( *:20 km for voth events) frut.' chis station provide constraints on the locations of these events in the NW SE direction (see Figure 6) As discussed earlier the locations of the 1955 events are in good agreement with the' instrumental data. This constraint and the distribution of tt intensity data (WGC,1979) indicate that the uncertainty is largely in the NE SW directica or basically along the magnetic boundary; which strengthen:, the ccrrelation of there events wl*h tne magnetic boundary.
The tvee older events (1885,1932 and 1943) are located sufficiently close to the magnetic boundary w!th uncertainties acceptably small as to render t%Ir correlation with the magner; boundary reasonably credible (Figure 7). The 1943 event (mblg 4.7) is the second largest earthquake known to have occurred in this reglon, and its instrumen-tally determined location is close to that of the 1986 event (Figure 7). The 1932 event was felt only on the west shore of Lake Summ3t (discussed earlier) located near the western edge of Akrm, tne city that lent Its nary 1 to the magnetic boundary. Lasciy, the distribu-tion of t'se intensity data for the 1885 event (see WGC,1979) suggests, as discussed earlier, that this ever.t probably occurred somewhat to the wc3t or northwest of the WGC epicentar shown in Figure 7, which would place it even closer to the ma9netic Dou . dry.
The above observations strongly suggest a causal relationship between seismicity and U1e Akror Magnetic Boundary in northeastern Ohio, indicating that t".e magnet 'oun-oary marks the locus of a pre existing fault or fault zone. Surficial geologic ', .a ap-parently do not s.:3w the trace of such a fault, cnd its preser .e at depto is probably masked by the sedimer JV cover. The magnetic data,in contrast, reflect changes in the basement rocks aiding i. .e < .F rstandirg of the structure of the upper crust. In this ccntext, it is notewort .y & M e well cc '" Sined hypocentrallocations of the af ter-shocks of the 1986 over- W"1ec . to 7 km (Figure 1); implying that the events occurred in the t . .s mentary cover.
The lateral (iiNE) extenc m "/ agure 7 suggests that the active portion of this fauit (zone)is at least act.. . . Judging from the focal mechanism solu-w l
1 23 1 l
/ * .-
. tions for the "86 event and its af tershocks it appears that this fault is predominantly a right lateral strike slip fault, and proboly has a down dip width of 1015 km as is general-ly the case for major strike slip faults.
IMPLICATIONS The preceeding results raise important safety issues and concerns regarding the level of earthquake hazard to which PNPP might be exposed. The design basis or the safe- ,
shutdown earthquake (SSE) for PNPP was established prior to the 1986 event on the basis of the tectonic province approach detailed in Appendix A,10 CFR 100 Of the Nuclear Regulatory commission. This approach is used in the absence of "capable faults", and/or where locations of historically reported earthquakes of highest intensity cannot be reasonably correlated with tectonic structures,in our opinion the resu'ts of this study demonstrate with reasonably certainty 1) that a major active fau;r nr fault zone exists in the proximity of PNPP, and 11) that an SSE of MM Intensity Vi! or mb about 5.3 adopted for PNPP does not provide the margin of safety required for nuclear oower plants, it is clear that the SSE for PNPP is only marginally larger than the 1986 event, bearing in mind that the intensity of the latter approached Vil, albeit in a few places. More impor-tantly, however, Appendix A mandates that in the event selsmological and geological data warrant, the SSE sh3IIbe larger than that derived by use of the procedures set forth In section IV and V of the appendix (see paragraph IV, section V). These procedures in-ciude the tectonic province approach. Hence, notwithstanding the issue of whether or not the fault zone identified here on the basis of seismological and magnetic data !s a "capable fault a3 "fined in Appendix A, it is clear that the results of this study warrant an Sh substantially largtr than th&t adopted for PNPP regardless of the approach used.
The ruoture ,rea associated v'ith the 1986 event (mb S.0) was 'n'.: red to be about 2 to 4 km2. In contrast, the estimated fault area (2 70 x 10 km2) potentially available for nJp-ture is more than 2 orders of magnitude larger than that associated with the 1986 event Theoretically, the available fault area is sufficient to accommodate a magnitude 7 or 24
- 4
, l
/
,' i
)
l l
even larger earthquake. Conservatively, however, the occurrence of a magnitude 6.5 earthquake must be considered a realistic possibility for the purposes of determining an SSE for PNPP. Furthermore, Figure 7 suggests that the fault zone extends NNE of the 1986 l event passing close to PNPP, which potentially places PNPP within the near field of a strong earthquake generated by this fault. The likellhood of occurrence of such an earthquake is, however difficult to quantify, and any efforts to do the same would be meaningless in light of the shortness of the historical record of earthquakes and the absence of geological data extending the record backward in time.
As to whether the fault Zone identified here is a "capable fault" within the context and meaning of Appendix A, we are of the opinion that the evidence favors such a designa-tion. According to Appendix A ff macro seismicity instrumentalIV determined with records of sufficient precision demonstrates a direct relationship with a fault. then that fault must be considered to be a cap 3ble fault. First, the events used in our correlation (Figure 7) range in magnitude from about 3.0 to 5.0, and hence constitute macro-seismicity. Secondly, the locations of the 1986,1983 and 1943 earthquakes are in-strumentally determined and those of the two 1955 events are partially constrained by instrumental data. As to whether these locations are determined with "sutilclent preci-slon to demonstrate a direct relationship", it is a matter of opinion, and we leave it to the reader to draw his or her own conclusions.
RECOMMENDATIONS We recommeno that the following confirma'ory Studies be undertaken to both verify the results of this study and seek geohgic entidence (which might or might not be available) for the existence of the fault zone discerned here on the basis of the assocla-tion of earthquakes with the Akron MLgnetic Boundary.
l} The magnetic data for northeastern Ohio should be reexamined in an effort to I
define the magnetic boundary as accurately as possible, in particular, the trend and the extension of this boundary north of the 1986 event should be defined (if l possible) more accurately taan at present.
I
! 25 L _ _
4
.t,e ,.
L
- 11) Using the magnetic data as a reference, the structural geology along this boundar /
should be studied carefully not only In the epicentral area of the 1986 event but also elsewhere. Sites that might be Sultable for this purpose are rivers, streams and takes that apparently follow tne boundary. Some examp!es are: Bass Lake and the river associated with it just SW of Chardon, the river and lakes or ponds between the towns of Geauga Lake and Burg Just NW of Aurora, and a NNs trending river (we
- . do not know the name) about 5 km west of Akron, 111) Several high resolution selsmic reflection profiles should be conducted across the magnetic boundary, it appears that the inferred fault Zone is essentially vertical and its possible that vertical displacements may have occurred on it during its geologic history. Such vertical displacements, if substantial, should be discernable on the seismic profiles. Tentatively we recommend four su:h profiles: NW of Akron near Aurora, near the epicenter of the 1986 event, and near Madison east of PNPP.
Iv) We also recommend that an attempt be made to further reduce uncertainties in the locations of earthnuakes that occurred prior to 1980.
- The 1943 event should be relocated using the 1986 earthquake as a master event. The inclusion of data from John Carroll station would be useful for this purpose.
- The available seismograms for the 19S5 events should be procured and ane'yz-ed. and the events should be relocated using both the instrumental and Inte'l-
- sity data.
- The felt reports for the older historical earthquakes of MM 2 IV should be reanalyzed and where possible additional data procured. The relocations should be obtained using computer based programs, and uncertainties should be ascertained taking into account the population distribution prevailing close to tne time of the occurrence of the event.
Lastly, this study clearly reiterates the desirability and need of seeking a spectrum of professional opinions, especially from those investigators not party to the issues involv-ed. Bearing this in mind, we strongly reccmrT'end that the unprocessed datE. resulting from any confirmatory investigations De made available to disinierasted Investigitors ,
and that fund'"* provided by governmental agencies to such investigators to facilitate the analyses anJ interpretation of the data. ,
26
\
r' -
e
' NOTES AND ACKNOWLEDGEMENTS
.we did not address the issue of whether or not the 1986 and 1983 events were trig-gered by injection of fluids at Calhlo welIs because of lack of sufficient funds. it is our 001-nion, however, that in order to clarify this issue and understand any spatio temporal relationships of these earthquake to fluid injection, one must take into account the loca-tion of the fault zone identified here and its possible influence on fluid flow.
This study was partially funded by the Ohio Citizens For Responsible Energy. The author cont.~lbut d a substantial portion of his time to this study.We thank AO Graphics Inc. for donating their valuable graghic services used in preparing this report, O
i 27
REFERENCES Cof fman, J.L., and von Hake, C.A., Earthquake History of the United States PL'D. No 411, U.S.
Dept. of Commerce /N.O.A.A., Boulder, CO.,1973.
Hern1 ann, R.B., and Nguyen, B.V., Focal Mechanism Studies of the January 31,1986 Perry, Ohlo, Earthquake, Abstracts, Sels. Soc. Am., East. Section, page 32.1986.
Hildenbrand, T.G., and Mucks, R.P., Residual Total Intensity Map of Ohlo, Map GP 961, U.S.
Geol. Survey, Reston, VA.,1984.
Seeber, L., The January 31,1986 Earthquake near Chardon, Ohio and its significance for the Perry Nuclear Power Plant and for Earthquake Hazard in the Eastern U.S., Testimony before subcommittee on Energy and Environment, U.S. House of Rep., Washington, D.C., AJril 18,1986.
U.S. Geological Survey, Studies of the January 31, 1986 Northeastern Ohio Earthquake, Wesson, R.L., and C. Nicholson Editors, USGS Open File Report, 86 336,1986.
Weston Geophysical Corporation (WCC), Evaluation of Local Seismicity around the Perry Nuclear Powei Plant Site, Appendix D, FSAR, prepared for Cleveland Flectric illuminating Co.,1979.
Weston Geophysical Corporation, investigations of Confirmatory Seismological and Geologicalissues, No.theastern Ohio Earthquake of January 31,1986, prepared for Cleveland Electric illuminating Co., June 1986.
28
p , !
, " ' *i-.
.:/* t APPENDIX B SEISMIC CAPABILITY OF THE 8x8 FUEL SPACER General Electric's 1975 Nuclear Reactor Study, known as the Reed Report, identifies the fuel as having the smallest seismic margin in the BWR/6. See attached page 39 of the Nucaear Systems Task Final Report. The fuel spacer is required to withstand an acceleration of 0.3 g. Doubt is expressed by GE'as to whether the BWR/6 design would meet seismic design requirements in excess of 0.3 g. In NUREG-1285, "NRC Staff Evaluation of the-General Electric Company Nuclear Reactor
-Study ("Reed Report") " , it is stated that fuel spacer failure -
could result in loss of core coolability during a loss of coolant accident (LOCA) (p. 22). That GE's standard plant design, GESSAR II, has as its maximum site SSE an acceleration of 0.3 g is indicative of this continuing seismic limitation in the BWR/6 design. (NUREG-0979, p. 15-2)
To illustrate that a near-field magnitude 6.5 earthquake would likely result in accelerations greater than 0.3 g, OCRE used the same correlations relied upon by the licensees in the FSAR. Represented graphically in FSAR Figure 2.5-74 (attached) are the relationships between acceleration and Modified Mercalli intensity developed by Trifunac and Brady (Reference 2 in FSAR Section 2.5), Gutenberg and Richter (FSAR Reference 151) and Newman (FSAR Reference 218). To correlate magnitude with epicentral Modified Mercalli intensity a number of
! relationships were employed. These are listed in Table 1. The mean of the values of intensity calculated for an earthquake of mb = 6.5 is 9.5. From FSAR Figure 2.5-74, a Modified Mercalli
7__-__ .
... 3- .
. ..
- r, .
/ * /
intensity of 9.5 yields an acceleration of 500 cm/sec2 for the relationship of Gutenberg and Richter, of 700 cm/sec2 for that of Trifunac and Brady, and of 800 cm/sec2 for that of Newman.
Taking 1.0 g to be 980 cm/sec2, these values translate to 0.51 g, 0.71 g, and 0.82 g.
REFERENCES Bernreuter et al., NUREG/CR-3756, Seismic Hazard Characterization of the Eastern United States: Methodology and Interim Results for Ten Sites, 1984.
Campbell, K.W., NUREG/CR-3839, An Empirical Assessment of Near-Source Strong Ground Motion for a 6.6 mb (7.5 Ms)
Earthquake in the Eastern United States, 1964.
General Electric Co. Nuclear Reactor Study ("Reed Report"),
'1975 l Gutenberg and Richter, Earthquake Magnitude, Intensity, Energy, and Acceleration, Bull. Seismol. Soc. Am., 32: 163-191, 1942.
Newman, Earthquake Intensity and Related Ground Motion, Univ.
of Washington Press, Seattle, Washington, 1954.
NRC, NUREG-0979, Supplement 3, Safety Evaluation Report Related to the Final Design Approval of the GESSAR II BWR/6 Nuclear Isla . Design, 1985.
NRC, NUREG-1285, NRC Staff Evaluation of the General Electric Company Nuclear Reactor Study ("Reed Report"), 1987.
Street and Turcotte, A Study of Northeastern North American Spectral Moments, Magnitudes, and Intensities, Bull. Seismol.
Soc. Am., 67: 599-614, 1977.
Trifunac and Brady, on the Correlation of Seismic Intensity Scales with the Peaks of Recorded Strong Ground Motion, Bull.
Seismol. Soc. Am., 65: 139-162, 1975.
, ingl tame %6 yw o v.- - .pfId.(t$ c: w agr1. m 4m w a...- e. w wua m ,
w.,.. y, .
. / *t O 'M There are at least five major arets that have a direct bearing on the overall safety with regard to scismic design. These areas are: definition of seismic loads, mathematical models, analysis procedures, design criteria and assuring quality control during fabrication and construction. Statistical data is lacking on which to assess the accuracy of assumptions in these areas in any design. Therefore conservatir m is appropriate.
BWRSD and BWRPD currently exercise parallel responsibilities in some areas of scismic design sincc BWRPD is responsible for the STRIDE design which is currently being developed through C. F. Braun. BWRSD hrs responsibility for the requisitions plants and most of the areas of responsibility regarding seismic design. However, within BWRSD these responsibilitics are diffused since some are assigned to development, '
others to design engineering, with essential responsibility assigned to the responsible design engineer even though he may not be sufficiently cognizant of t'e "state of the art" design basis that is characteristic of seismic design,
's The component of BWR/6 having the smallest seismic margin for the present method of RPV support is the fuel. The fuel-spaccr-channel combination is required to meet the 0. 3g ground acceleration se'ismic r equir eme nt s. Since it has been difficult to design ths spacer to meet
, scismic margin teguther with thermal and nuclear design requirements, j
there is question whether the BWR/6 design would meet scismic conditions for sites where the requiremerts are in excess of 0. 3g. Because many models (mostly analytical) and not many tests have been used to establish
, this esmic desien, future tes ts will be required to verify adequacy should it be discovered that one of the models exercised in the fuel performance '
tr uic-off study ir. inadequate. While the scismic analyscs have concluded that the fuel-spaccr-channel desi n C is adequate for 0. 3g, tests performed for 0. 3g scismic conditions indicate rome deformation which is not in accordance with the design criteria, therefore, the criteria, test conditions or the spacer design must change.
In many cascu, scismic requirer,cnts are specified by GE for GE supplied equipment but the A/E has control over how (or if) the requirements are met.
The PWR design is inherently more scismic t esistant because of lower reacto- vessel placement and the need to design for larger LOCA loadings.
4.4.4 Radiological Contamination Finding:
The uncovered suppression pool of Mark III causes Mark III to be more susceptible than previous designs to loss of availability due to present )
occupational dose limits and a, fortiori to mure strin;;cnt regulations which l a r. ., n t icipa t ed . Mark I and Mark 11 designs may aluu be affected by increased i
difficulty in performing required maintenance and backfit if required. l 1
I
. _1
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..l; C[?g ' 7,.
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TABLE 1
. Relationship Reference lo for mb=mbLg=6.5 mbLg= 0.49Io + 1.66 Eq. 9, p. 605 of or Street & Turcotte 9.87 Io= 2.04 mbLg - 3.39
.Io= 2.07 mb - 3.97 Eq.-16a, p. 15 of NUREG/CR-3839 9.49 Io= 1.98 mb - 3.41 Eq. 16b, p. 15 of NUREG/CR-3839 9.46 Io= 2 mb - 3.5 Eq. 19, p. 18 of NUREG/CR-3839 9.5
, Io= 2.16 mbLg - 4.4 p. A-67 of NUREG/CR-3756 9.64 i'
mb= 0.44 + 0.67 Io p. A-75 of NUREG/CR-3756 or .
9.03
, Io= 1.49 mb -0.657 Mean Io = 9.5 I
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.....f April 28,1988 ff ,
IIEMORANDUll FOR: .Kenneth E. Perkins..Directora Project Directorate III-3 Division of Reactor Projects III/IV/V and Special Projects FROM: Goutam Bagchi, Chief Structural and Geosciences Branch Division of Engineering and Systems Technology
SUBJECT:
OCRE 2.206 PETITION FOR IMMEDIATE AtTION TO RELIEVE UNDUE RISK POSED BY THE INADEQUATE SEISMIC DESIGN OF THE PERRY NUCLEAR POWER PLANT (TAC N0. 671:1)
References:
Petition by the Ohio Citizens for Responsible Energy, Inc.
(OCRE), dated January 22, 1988 In reply to your request for assistance on the subject matter, we have prepared a Safety Evaluation Leport (attar.hed) which addresses the assertions made in the above referenced petition regarding the adequacy of the Perry Nuclear Power Plant (PNPP) seismic design. We find that the arguments stated in the OCRE petition indicating the presence of a large capable fault which could generate a magnitude 6.5 or greater earthquake in the vicinity of the PNPP cannot be substantiated. Therefore, we find that the request for a suspension of the license in order to conduct additional geological and geophysical studies and engineering evaluations is unwarranted.
I Goute Bagchi, Chief Structural and Geosciences Branch Division of Engineering and Systems Technology
Attachment:
As stated cc: L. Shao J. Richardson G. Holahan T. Colburn R. McMullen si
2.206 Petition On Perry Nuclear Power Plant Seismic Design Safety Evaluation Report Structural and Geosciences Branch By a Petition submitted pursuant to 10CFR Section 2.206 and dated January 22, 1988, Ohio Citizens for Responsible Energy, Inc. (0CRE) requested that the Director of the Office of Nuclear Reactor Regulation suspend the Operating License (0L) and the Construction Permit (CP) for the Perry Nuclear Power Plants.
The petition alleged that:
- 1. The January 31, 1986 Chardon, Ohio earthquake and the historic seismicity near the Perry Nuclear Power Plants (PNPP) could be associated with a tectonic structure (fault), revealed by magnetic data.
- 2. The tectonic structure so identified is capable of a magnitude 6.5 or greater earthquake.
- 3. The present Safe Shutdown Earthquake (magnitude 5.3 0.5) does not provide the margin of safety required.
- 4. The licensee, Cleveland Electric Illuminating Company (CEI) is therefore in violation of regulations promulgated under the Code of Federal Regulations 10 CFR 50, Appendix A, General Design Criterion 2 and 10 CFR 100 Appendix A, Parts IV, V, and VI.
The basis for these contentions is a report by Dr. Yash P. Aggarwal on behalf of the petitioners. In the report Dr. Aggarwal asserts that an earthquake of magnitude 6.5 or larger is probable on a feature which, at its closest approach, is approximately 10 km south east of the PNPP site. This feature is a "boundary" in the magnetic map of the Ohio which separates a region of relatively high magnetic relief to the northwest from a region of relatively low magnetic relief to the southeast. Weston Geophysical Corporation (WGC) identified this boundary as the "Akron Magnetic Boundary" (AMB), (Reference 1, Figure 4-2). OCRE requested that the OL and CP remain suspended until the licensee performs additional geological and geophysical studies to evaluate systems, structures and ccmponents important to safety given the increased seismic loading. This evaluation should include the 8X8 fuel spacer speci-fically mentioned in Appendix B of the above petition.
Dr. Aggarwal based his findings, to a large extent, on recent studies performed by Weston Geophysical Corporation (Reference 1) on behalf of CEI, by the U.S. Geological Survey (Reference 2) on behalf of the U.S. Nuclear Regulatory Comission (NRC); and on testimony before the U.S. House of Pepresentative by Dr. L. Seeber (Reference 3).
Since the occurrence of the January 31, 1986 earthquake in the vicinity of the PNPP site, numerous investigations have taken place with the sole purpost of studying the 1986 earthquake, its aftershocks, the possible causative structure, and by inference the relationship with deep-well fluid injection.
The concerns enumerated above have been discussed extensively in supplements to the Perry Safaty Evaluation Peport (SER) (Reference 4). The conclusions arrived at by tht: NRC staff after reviewing all available pertinent information on the geological and geophysical characteristics of the northeastern Ohio region
was that no discernable geological st'ucture(s) had been identified which could be associated with the January 31, 1986 earthquake and that the earthquake by itself was not uncharacteristic of the general earthquake history of the tectonic province (Central Stable Region) in which the PNPP is located. The staff still considers these conclusions to be valid.
Since the publication of the above supplemental SER's the utility (CEI) has continued monitoring of the seismic activity in the vicinity of the PNPP site.
To date, five quarterly reports have been submitted to the NRC (References 5-9) fcr review. The cumulative activity recorded by the network (Reference 9, Figure 4) exhibits some microseismic accivity in the corridor covered by the network. The epicentral locations of these very small tremors (with magnitude range - 0.7 to 1.3) form a small cluster, parallel to and slightly offset from the AMB. Our experience indicates that the occurrence of earthquakes of this size are typical of many locations within the eastern U.S.
at different times and are only detectable when a highly sensitive seismic network is used such as that employed by CEl. These events by themselves do not indicate potential for large and possibly damaging earthquakes.
The NRC has received also a preliminary report (Reference 10) which discusses the July 13, 1987 Ashtabula, Ohio earthquake and its aftershock sequence. In addition to the discussions on the 1987 Ashtabula events the preliminary report (Reference 10) mentions also the January 31, 1986 Chardon, Ohio earthquake.
The authors, including Dr. Seeber who originally proposed it, (Reference 3) recognize, as Dr. Aggarwal did, the association of this event with the NNE trending AMB and assert that the correlation indica *es that the magnetic feature could be an expression of 3 (reactivated) fault of considerable length on which earthquakes much larger than the 1986 event could occur. However, it should be pointed out that the authors themselves state that because of the lack of any evidence of the extension of this postulated fault into the paleozoic platform cover (upper 2km of rock strata) very large ruptures involving much of the fault are unlikely.
Dr. Aggarwal argues that the mair shock and aftershock focal mechanisms indicrte a fault app.oximately N30*E colinear with the AMB. While a general NNE trend of the main shock and aftershock focal mechanisms appears to be inferred, the uncertainty associated with Dr. Aggarwal's preferred orientation is larger than he indicates. For example the most recent study of tb 1986 earthquake (Reference 11) indicates that the northeast trending plane of the main shock could vary from N22 E to N55 E depending upon the type of seismic wave analyzed. Dr. Aggarwal appears to be incorrect in his assertion that Hermann & Nguyen (Reference 13) defined a possible source of the earthquake as being a N28 E westward dipping fault (82 ). Dr. Hermann (personal communication 1988) indicated that this possible source uould be a N21'E eastward dipping fault. Similarly Reference 11 states that the variations in the trend of preferred nodal planes (fault planes) is probably due to the fact that more than one favorably oriented weak fracture is being reactivated by the change in stress associated with the main shock.
Dr. Aggarwal suggests that several of the earthquakes which occurred in recent history have a sufficient error band in their epicentral location that they can be also associated with the AMB. Dr. Aggarwal asserts that *,he error in location can be attributed to soil amplification effects, bias as a result of population density and/or errors in methods of locating earthquake epicenters on the basis of felt reports or insufficient instrumental data.
t e
While the staff agrees with Dr. Aggarwal's assertions that most historical earthquakes discussed have poorly located epicenters, we C sagree with his, y 7 assertion that they can be correlated with the Akron Magnetic Boundary, JP/v 2 , - e
/Nhv5 inferring a fault on which the occurrence of an earthquake much larger than p' the magnitude 5.0 earthquake of January 31, 1986 "must be considered a - .
realistic possibility". The staff bases this conclusion or, the following observations:
- 1. The January 31, 1986 earthquake itself is not uncharacteristic of the general earthquake history of the tectonic province which includes the 1937 Anna Ohio earthquake, the 1982 Sharpsburg Kentucky earthquake, and many other earthquakes in the magnitude 5.0 to 5.5 range.
- 2. The nature and depth of the geologic feature or features manifested by the AMB have not been determined. Throughout the eastern U.S. there are many magnetic features and many earthquakes the size of the 1986 Ohio event. Some of these earthquakes are near anomalous magnetic features ar.d others are not. Magnetic boundaries indicate changes in rock properties. However there is no basis to assume, as Dr. Aggarwal does, that these changes in rock properties necessarily indicate faults and that they are capable of lcrge ruptures.
- 3. Dr. Aggarwal uses the macroseismicity criterion in Appendix A to 10 CFR, Part 100 to identify the AMB as a capable fault. Past use of macroseismicity to identify capable faults has proven to be a difficult process. Macroseismicity has been considered to be a level of seismicity that implies significant, sustained, and coherent tectonic activity representative of major deformational movement within the earth's crust (Reference 12). Dr. Aggarwal has identified six historic earthquakes, one of magnitude 4.7 and five in the magnitude 2.7 to 3.8 range that hav occurred since 1885 which, because of location uncergpfy lgs_offQhis ms dQ correlation is highly questionab'e since he neglects so show/that There -
are other earthquake o:currences in northeastern Ohio whose ?ocation.
cannot be associated with the AMB. These include many earthquakes to the west, in the vicinity of Cleveland, Ohio and most recently the inagnitude 3.6, July 13, 1987 earthquaFe, discussed in Reference 10. This very well located event, apparently triggered by fluid injection, occurred some 25 km east of the AMB on an east-west trending fault. Therefore the small number of earthquakes, raost of which are less than magnitude 4, the large uncertainty in their location and the occurrence of earthquakes in areas i not associated with the AMB do not, in the staff's opininn, constitute an appropriate use of macroseismicity to idcntify a capable fault.
In conclusion, we find that the arguments stated in the OCRE petition indicating the presence of a large capable fault which could generate a magnitude 6.5 or greater earthquake in the vicinity of the PNPP cannot be substantiated. Therefore the request for a suspension of the license in order to conduct additional geological and geophysical studies and engineering evaluations is unwarranted, j The NRC staff however is aware tnat the northeastern Ohio region is an area of continuing investigation by the NRC, uriiverstiy groups and CEI which, as indicated previously, is monitoring microseismicity in '.ne vicinity of the plant. The staff is keeping informed of studies being performed in the region and will evaluate the rasulting reports with respec+ to char,ges in the above conclusions and any impact they might have upon the seismic safety of the PNPP.
i _
While the staff agrees with Dr. Aggarwal's assertiu s that most historical earthquakes discussed have poorly located epicenters, we disagree with his assertion that they can be correlated with the Akron Magnetic Boundary inferring a fault on which the occurrence of an earthquake nuch larger than the magnitude 5.0 earthquake of January 31, 1986 "must be considered a realistic pssibility". The staff bases this conclusion on the following observation;:
- 1. The January 31, 1986 earthquake itself is not uncharacteristic of the general earthquake history of the tectonic province which includes the 1937 Anna Ohio earthquake, the 1982 Sharpsburg Kentucky earthquake, and many other earthquakes in the magnitude 5.0 to 5.5 range.
- 2. The nature and depth of the geologic feature or features manifested by the AMB have not been determined. Throughout the eastern U.S. there are many magnetic features and many earthquakes the size of the 1985 Ohio ,
event. Some of these earthquakes are near anomalous magnetic features and others are not. Magnetic boundaries indicate changes in rock properties. However there is no basis to assume, as Dr. Aggarwal does, '
that these changes in rock properties necessarily indicate faults and that they are capable of large ruptures.
- 3. Dr. Aggarwal uses the macroseisinicity criterion in Appendix A to 10 CFR, Part 100 to identify the AMS as a capable fault. Past use of macroseismicity to identify capable faults has proven to be a difficult l process. Macroseismicity has been considered to be a level of seismicity that implies significant, sustained, and coherent tectonic activity representative of major deformational movement within the earth's crust (Reference 12). Dr. Aggarwal has identifieu six historic earthquakes, one of magnitude 4.7 and five in the magnitude 2.7 to 3.8 range that have occurred since 1885 wh::h, because of location uncartainties of this <
correlation is highly questionable since he neglects to show that there MN A are other earthquake occurrences in northeastern Ohio whose location, 'M et cannot be associated with the AMB. These include many earthquakes to the west, in the vicinity of Cleveland, Ohio and most recently the magnitude 3.6, July 10, 1987 earthquake, discussed in Reference 10. This very well located event, apparently triggered by fluid injection, occurred some 25 km east of the AMB on an east-west trending fault. Therefore the small number of earthquakes, most of which are less than magnitude 4, the large uncertainty in their location and the occurrence of earthquakes in areas not associated with the AMB do not, in the staff's opinion, constitute an appropriate use of macroseismicity to identify a capable fault.
In cenclusion, we find that the argur.ents stated in the OCRE petition indic:. ting the presence of a large capable fault which could generate a magnitude 6.5 or greater earthouake in the vicinity of the PNPP cannot be substantiated. Therafore the request for a suspension of the license in ,
order to conduct additional geological and geophysical studies and t engineering eveluations is unwarranted.
The NRC staff however is aware that the northeastern Ohio region is an area of continuing investigation by the NRC, universtiy groups and CEI which, as indicated previously, is monitoring microseismicity in the vicinity of the plant. The staff is keeping informed of studies being performed in the region and will evaluate the resulting reports with respect to changes in the above conclusions and any impact they might have upon the seismic safety of the PHPP.
'