ML19225C118
| ML19225C118 | |
| Person / Time | |
|---|---|
| Site: | Haddam Neck File:Connecticut Yankee Atomic Power Co icon.png |
| Issue date: | 06/11/1979 |
| From: | Levin H Office of Nuclear Reactor Regulation |
| To: | Office of Nuclear Reactor Regulation |
| References | |
| TASK-02-04, TASK-RR NUDOCS 7907260505 | |
| Download: ML19225C118 (6) | |
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NUCLEAR REGULATORY COMMISSION E
WASHINGTON, D. C. 20555 3
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DOCKET NO. 50-213 DATE: June 11, 1979 LICENSEE:
Connecticut Yankee Atomic Power Company FACILITY:
Haddam Neck Nuclear Plant
SUBJECT:
MEETING SbMMARY - HADDAM NECK SEP GE0 LOGY / SEISMOLOGY REVIEW Members of the Nuclear Regulatory Commission staff and respresentatives of the Connecticut Yankee Atomic Power Company (CYAPCo.) met in Bethesda, Maryland, on May 16, 1979, to discuss Geology and Seismology issues related to the Systematic Evaluation Program (SEP) review of the following topics:
II-4A - Tectonic Province II-4B - Proximity of Capable Tectonic Structures in Plant Vicinity II-4C - Historical Seismicity within 200 Miles of Plant III Seismic Design Considerations The attendance list is included in Enclosure 1.
The objective of the meeting was for the NRC staff to sumarize details of recent geologic studies in the vicinity of the Haddam Neck site by nany investigators and to discuss items of additional information that '.,ill be required and other items being considered to complete the SEP geology /
seismology review. These items are sumarized in Enclosure 2.
The staff noted that the issues being r ised result from recent information developed about the site that would require resolution even if the SEP did not exist.
The recent south-central Connecticut geology / geophysical studies have included geologic mapping, age determinations, aeromagnetic and gravity surveys and the installation of a seismograph array. These activities were highlighted at a symposium on the Moodus Region, Connecticut, held at Wesleyan University, Middletown, Connecticut on Apcil 19-20, 1979.
A long history of low-magnitude seismic activity has been encountered in the East Haddam-Moodus area which is about three miles from the Haddam Neck site.
The recent efforts have attempted to correlate the earthquake epicenters with geologic structures in the area. Work by J. W. Block, et al., documented in an article appearing in Geology Magazine, Volume 7, entitled, "Recent Thrust Faulting in Southeastern Connecticut suggests the possibility of creep along fault P anes as evidenced by offsets in drill holes made for roadcut l
blasting in the vicinity of the Honey Hill fault zone.
The offsets in the drill holes occur in the upper (north) plate of the Honey Hill fault at several locations along Connecticut State Route 11 from 1 to 8 Km north of the fault surface trace.
The cause of the observed displacements may be interpreted to oe the result of the blasting, stress relief or possibly due to tectonic forces; however, conclusive studies do not exist.
413 191 7 9 07 '2 6 0 f6
Meeting Summary for June 11, 1979 Haddam Neck Plant The NRC staff explained that information is required to explain the cause of the displaced drill holes to fully assess whether there is a potential for generating seismicity.
It is felt that this information must be supplemented with information showing the spatial, structural and age relationship of the Honey Hill and Bonemill faults and other fausting to determine the implicrtions, if any, to the site.
The discussions indicated that a significant amour.c of pertinent informatien may exist.
The representatives of CYAPC0 indicated that they would further discuss the issues presented at the meeting with their consultant, Weston Geophysical, Inc. in an effort to determine what actions they might be able to take to adequately address these issues and the timeframe for completing any work.
The licensee stated that he would get back to the NRC staff with a proposed action plan by mid-June.
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Howard A. Levin Systematic Evaluation Program Branch Division of Operating Reactors
Enclosures:
1.
List of Attendees 2.
Pertinent Information Required to Document the Geology / Seismology of the Haddam Neck site cc w/ encl:
See next page AI3 192
ATTENDANCE LIST SEP GE0 LOGY / SEISMOLOGY REVIEW HADDAM NECK NUCLEAR PLANT MAY 16, 1979 NRC Howard Levin, DOR Charles Hofmayer, 00R Robert Jackson, DSE Leon Reiter, DSE Thomas Cardone, DSE NORTHEAST UTILITIES SERVICE COMPANY Robert Smart Barry Ilberman WESTON GEOPHYSICAL, INC.
Richard Holt 413 193
PERTINENT INFORMATION REQUIRED TO DOCUMENT THE GE0 LOGY / SEISMOLOGY OF THE HADDAM NECX SITE The NRC staff has completed a review of the Haddam neck docket and data available from other sources for information pertinent to the Geology /
Seismology of the Haddcm Neck site. The information currently on the docket is not sufficiently complete to adequately address geology / seismology issues in order to re-evaluate the seicaic design bases of the facility.
It is anticipated that soma of the required information may be available but not on the docket; however, other items will require the generation of a limited amount of taw information. The following items require further consideration by CYACPo.
GEOLOGY 1.
With regard to the offsets in drill holes made for roadcut blasting which are discussed in an article appearing in Geology Magazine, Volume 7, entitled, "Recent Thrust Faulting in Southeastern Connecticut," by Block, J.
M., et al, the following information is required:
- a. fampilation id update of the offset measurements data, and informatior i the residual stres_/ strain con:"tions, which hac been develop
'n the subject of the offset drill holes.
b.
Discussion of the _rigin of the displacements, and if they may indicate a consistent southward overthrusting of the northern block of the Honey Hill fault zone; and relevant analyses of residual stress / strain of that fault.
The meaning of the apparent release of residual stress that is c.
occurring and an assessment of the regional geologic and seismic implications and any possible relationship that this could have on historic seismic activity in the Moodus area.
The above information is required to explain the cause of the displace.d drill holes.
If the cause is tectonic, the potential for generating seismicity and the m&ximum size of the events would need to be addressed.
2.
Compilation of pertinent available information on the Bonemill fault, addressing its spatial, structural, and age relationship to the Honey Hill fault, and a determination of the period of last movement of the Bonemill fault.
(This will better describe the structural geolo,, its age relationship to other faultina, and indirectly its implicai 'n to the plant site).
3.
An assessment includin; a determination of the most probable period of last movement, of the system of northeast trending faults mapped by David London, Arizona State University.
A discussion of the spatial, structural and age relationship of this system of faults to the Bonemill and Honey Hill faults.
(This will better describe the structural geology, its age reiationship to other faulting, and indirectly its implication to the plant site).
413 194
_2 4.
A geologic map of the site area, which in particular demonstrates the spatial relationship of the systems of faulting mentioned above to the nuclear Plant site, and which identifies any other faulting in the site area. This can probably be accomplished by assembling available information and providing necessary field mapping and sampling where necessary to finalize mapping in.the site crea.
An evaluation of the capability of all faults and fault systems closest to the site using the 09idance and metnodology set forth in U.S. Nuclear Regulatory Commission Reaccu, Siting Criteria, Appendix A to 10 CFR Part 100. Samples of the mineralization would be useful to determine the age of faulting in the region.
5.
Compilation of aeromagnetic and gravimetric maps of the site area, and other remote sensing information pertaining to geologic structure around the site.
o.
Consideration of in-situ stress measurements.
SEISMOLOGY 1.
The following information is required to understand the impact of the historical and instrumental.
smicity of the Moodus area on the plant
- site, a.
A listing and evaluation of Intensity of the Historical events.
b.
A listing and plot of the location of the Instrumental events.
c.
A comparison of these events with others in New England.
d.
A discussion of the possible tectonic origin of these events including association with any known fault or structure.
413 195