ML17309A209

Submits Results,Conclusions & Recommendations from Insps of Engineering & Operational Aspects of Existing Stone Revetment Along Lake Ontario Shore

ML17309A209
Person / Time
Site:	Ginna
Issue date:	12/10/1981
From:	Johnson G ARMY, DEPT. OF, CORPS OF ENGINEERS
To:	NRC
References
NCBED-DC, NUDOCS 8112180419
Download: ML17309A209 (29)

Text

'r DEPARTMENT OF THE ARMY BUFFALO,OISTRICT, CORPS, OF ENGINEERS

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,BUFFALO,, NEW,YORK'J4207 10 December 1981

SUBJECT:

R'E. GINNA" Nuclear"Generating Plant,'own of Ontario, NY f 0

'f rr Prospect Of ficer .

United States Nuclear'egulatory'Commi Washington, DC '0555 1 ~

REFERENCE:

a. Statement of Work for CERCWINNA Nuclear Power Plant Docket No. 50-244 (see Exhibit 1).

b. Rochester Gas and Electric Corporation letter to Director of Nuclear Reactor Regulation, dated 28 January 1981, transmitting RG&E responses to NCR Evaluation of SEP Topics II-3.A, II-3.B; II-3.C, "Hydrology, Plooding, and Ultimate Heat Sink" (see Exhibit 2) ~

c. U.S. Nuclear Regulatory Commission memorandum for Chief, Systematic Evaluation Program Branch, dated 3 March 1981, containing NRC responses to Rochester Gas and Electric comments on SEP Topics II-3.A, II-3.B, and II.3.C (see Exhibit 3).

d. U.S. Nuclear Regulatory Commission letter to Rochester Gas and Electric Corporation, dated 10 April 1981, transmitting NRC evaluation of Systematic Evaluation Program Topics II-3.A, II-3.B, II-3.C (see Exhibit 4).

e. Rochester Gas and Electric Corporation letter to Director of Nuclear Reactor Regulation, dated 1 May 1981, transmitting RG&E responses to NRC correspondence on SEP Topics III-3.A (24 Mar 81)- and II-3.A, II-3.B, II-3.B.1 and II-3.C (10 Apr 81) (see Exhibit 5) ~

f. Rochester Gas and Electric Drawing Numbers 33013-171 and 33013-51E, Plan and Sections of GINNA revetment (not included) ~

g. Buffalo District, Corps of Engineers letter to Prospect Officer U.S.

Nuclear Regulatory Commission, dated 2 November 1981, transmitting memorandum for the Record Trip Report Concerning Stone Revetment at R.E. GINNA Nuclear Generating Plant (see Exhibit 6) ~

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SUBJECT:

R.E. GINNA Nuclear Generating Plant, Town of Ontario, NY PURPOSE OF REPORT

2. This letter report presents the results, conclusions, and recommendations arising from inspections of the engineering and operational aspects of the existing stone revetment along the lakeshore on Lake Ontario at the R.E.

GINNA Nuclear Generating Plant.

SCOPE OF REPORT

3. This letter report will serve as the Corps of Engineers technical opinion on the adequacy of the existing stone revetment at the R.E. GINNA Nuclear Generating Plant.

AUTHORIZATION

4. This letter report was prepared by the Buffalo District, Corps of Engineers in response to Coastal Engineering Research Center Interagency Agreement No. NRC-03-81-110 Proposed Work Directive 1 entitled "Statement of Work for CERC GINNA Nuclear Power Plant Docket No. 50-244" (Reference la).

LOCATION AND DESCRIPTION OF EXISTING STONE REVETMENT

5. The R.E. GINNA Nuclear Generating Plant is located in the town of Ontario, NY, on the south shore of Lake Ontario, approximately 20 miles east of the city of Rochester, NY. The stone shore revetment is along the shore-line on the north side of the plant and protects the main building complex from wave attack by Lake Ontario. The licensee of the R.E. GINNA Nuclear Generating Plant is the Rochester Gas and Electric Corporation.

6. The stone revetment was constructed in two reaches: an estimated 420-foot long west reach and an estimated 400-foot long east reach. The east and west stone revetment reaches are separated by a 20-foot wide discharge canal from the generating plant (see Plates 1 and 2)- According to Section A-A and Section B-B on Drawing No. 33013-51E Reference 1f), the stone revet-ment was initially constructed in the 1960's with two layers of 5-ton minimum armor stones laid up on a 1.0 vertical on 1.5 horizontal sideslope to a mini-mum elevation of 257.0 (msl). Due to the high lake levels that were pre-dicted for Lake Ontario during the early 1970's, the crest elevation of the revetment was raised to a minimum of 261.0 (msl) by placement of cap stone along the top of the revetment. Typical cross-sections of the east and west reaches of the stone revetment are shown on Plates 3 and 4.

DESCRIPTION OF PROBLEMS UNDER INVESTIGATION

7. Section 3.3.0 of the Nuclear Regulatory Commission evaluation of the Systematic Evaluation Program (Reference ld) states that visual observations during the SEP site visit indicate the revetment fronting the plant on the west side of the discharge canal -is significantly degraded. The evaluation notes that portions of the revetment would be incapable of providing adequate protection from wave attack during a severe storm, up to and including the

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R.E. GINNA Nuclear Generating Plant, Town of Ontario, NY Probable Maximum Water Level (PMWL), resulting from the Probable Maximum Surge (PMS) on Lake Ontario which is the design basis flood for the revetment. The NRC staff calculates that about 2.5 feet of water would be ponded in the vicinity of the screen house and discharge canal submerging emergency buses if the revetment is eroded significantly and the design basis storm occurs. An NRC analysis of the stability of the revetment indicates that the revetment would be capable of resisting the Lake Ontario PMWL and associated wave action and would, therefore, meet current regulatory criteria provided the revetment exists as designed.

8. Rochester Gas and Electric Corporation responses regarding the NRC assessment on the SEP Topic Section 3.3.0 Lake Ontario Flooding (References 1b and le) cite that inspections made by RGM have been unable to find any visible evidence of degradation of the revetment fronting the plant on the west side of the discharge canal. RG6E determined that the revetment is structurally sound and comparable to the requirements of the original specifications. RGM believes that the appearance of degradation indicated by the NRC may be due to the placement of loose that fill on the revetment in 1973. The following upgrading (cap stone placement) was performed RG&E response indicates of that this loose fill is performs no function sub-base in relation material to the requirements the revetment and simply excess which was used to dual armor stones.

fill natural occurring voids in the joints between indivi-

9. The NRC staff has reviewed the design of the revetment, the flood design basis thereof, and the consequence of failure during a severe storm event if the armour stones were not adequate. The NRC assessment indicates that the original revetment design was adequate, however, a NRC site visit indi-cated that portions of the revetment on the west side of the discharge canal appeared to have been degraded in terms of the number and sizes of stones at several locations. Therefore, the Corps of Engineers was requested to pro-vide a technical opinion of the adequacy of the existing revetment and to suggest ways that the revetment may be repaired if not found adequate.

OBSERVATIONS FROM FIELD INSPECTIONS

10. In response to several FONECONS betweens Mr. Charles Johnson of North Central Division, Corps of Engineers, and Mr. Richard Gorecki of Buffalo District, Corps of Engineers, the District Corps Office was requested to make a site inspection of a stone shore revetment at the R.E. GINNA Nuclear Generating Plant. The purpose of the site inspection was to make visual observations of the revetment in order to provide a technical opinion of the adequacy of the stone shore revetment which protects the main building complex from wave attack by Lake Ontario.

11. On 21 October 1981, Mr. Richard Gorecki of the Buffalo District Coastal Engineering Section and Mr. Jon Kolber of the Buffalo District Geotechnical Section met Mr. Gary Goetz of Rochester Gas and Electric Corporation at the R.E. GINNA plant site (References 1g). Mr. Goetz, the project engineer for

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R.E. GINNA Nuclear Generating Plant, Town of Ontario, NY the revetment construction project, guided the Corps representatives on an inspection of both the east and west reaches of the stone revetment. The inspection team did not note any significant displacement of stones in the sideslope on the lakeward face of the structure nor any unusual depressions in the structure sideslope or crest. The fence which is adjacent to the backside of the west reach of the revetment appeared to be plumb and have an alignment that runs parallel to the revetment, thereby, indicating that there has been no appreciable movement of the fill material behind or under the revetment. On the east reach of the revetment, there were no apparent depressions or slippages evident in the backslope of the compacted earth dike, thereby, indicating that there has been no appreciable movement of the fill material under the revetment.

12. The armor stones on the lakeward face of both the east and the west revetment reaches were covered and obscured by stone in the 4 to 9-inch range in several areas. Therefore, it was imposs'ible to positively determine the existence of two layers of armor stones at these locations, .which were required by the final design, particularly, at the west end of the revetment where a larger concentration of the estimated 4 to 9-inch stone had been placed. It could not be verified that the revetment is of adequate design in the areas where the small stone had been placed without removing the small stones. Therefore, Mr. Gary Staley of NRC contacted the licensee and directed them to remove the small stones in a few locations such that a visual inspection of the revetment could be made to insure that the double layer of armor stone is in place.

13. On 13 November 1981, a second site inspection was conducted. The inspection team consisted of the following personnel:

Gary Goetz Rochester Gas and Electric Corporation George Wrobel Rochester Gas and Electric Corporation Gary Staley Nuclear Regulatory Commission Thomas Wilkinson Corps of Engineers Jonathan Kolber Corps of Engineers Richard Gorecki Corps of Engineers The licensee removed the small stones in two areas on the west end of the west reach of the revetment. Inspection of these two areas indicated that the double layer of armor stone is intact and that the small stone was not underlayer material as was suspected during the NRC Systematic Evaluation Program site visit. Further inspection of the west reach of the revetment disclosed an area, located approximately midway on the revetment,, where there may have been minor movement of the armor stone layer. Discussions with Mr. Gary Goetz indicated that waste concrete had been dumped at this location and the toe stone could not be properly placed due to the concrete-The armor stone apparently slid on the concrete into what appears to be a stable position, thereby causing minor movement on the face of the revetment at this location.

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14. The large void on the east revetment reach which was observed during the 21 October 1981 inspection was reexamined during the 13 November 1981 inspection. The void is about 100 feet east of the west end of the east revetment and extends for about 25 to 30 feet directly under the cap stones which bridge the void with little rock-to-rock contact over the void- This void is apparantly due to a construction oversight not a structural failure.

15. The east and west ends of the revetment reaches terminate and tie into the natural high bluff away from the main (reactor) building complex.

Although erosion had occurred in these bluff areas, probably during the high lake levels of the early 1970's, there was no evidence of current active bank erosion since the bluff faces are covered with vegetative growth probably several years old.

CONCLUSIONS

16. The stone revetment has been in place for approximately 15 years. Based upon a review of the material furnished by NRC (References la through 1f) and on visual observations from the 21 October 1981 and 13 November 1981 site inspections, there is no evidence where the existing revetment is in any immediate or foreseeable future danger of failing. The revetment appears to be structurally sound and stable with no evidence of any ma)or structure sta-bility problem and based on its performance to date, the anticipated durabi-lity and survivability of the revetment, as constructed, should exceed the life of the plant (i.e., the nuclear vessel which has an estimated life of about 25 years). The two site inspections verified that the revetment has not degraded from the original design and that the small stone at various locations along the lakeward face of the revetment is waste material that had been placed to fill voids between the large armor stones. Although there are some cracked armor stones, the actual gradation appears to be larger than required to provide adequate protection from wave attack, such that even the cracked stones should be of sufficient size to withstand the most severe wave attack that could be expected at the site.

17. There is the possibility that the revetment ends adjacent to the high bluffs can be flanked by erosion during high lake levels or during an extreme infrequent storm, thereby, causing damage to the revetment. However, the main building complex is far enough away from the ends of the revetment that there would be no immediate danger to the facility even 'if the revetment is flanked and damaged.

RECOMMENDATIONS

18. The east side of the revetment is in excellent condition, however, the large void should be filled with concrete or large enough stone such that they will not pass through the voids in the armor layer.

19. A monitoring program should be implemented by the licensee in order to, detect 'future movement of the armor stone. The program should consist of an initial survey to establish vertical and horizontal control and to establish

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R.E. GINNA Nuclear Generating Plant, Town of Ontario, NY permanent points at which subsequent survey data would be obtained. Cross-sections of the revetment should be obtained at stations located approxi-mately 100 feet apart. On the lakeward side of both the east and west reaches of the revetment, permanent survey points on each cross-section sta-tion should be established at the toe of the revetment, the top of the revetment, and top of the cap stone. On the west reach of the revetment, permanent survey points should also be established on the top and base of the concrete retaining wall while on the east reach, survey points should be established on the crest and at the toe of the earth dike. Recommended per-manent survey points for each cross-section station are shown on Plates 5 and 6. In addition, nearshore lake bottom elevations should be obtained at each station out to the wading depth limit. The initial survey should be conducted in the spring and be compared to "as built" drawings in order to determine if there has been any settlement since construction of the revetment. Each subsequent survey should be made at 2 year intervals and be compared to the initial and previous survey in order to detect any move-ment of the armor stones.

20. This Letter Report presents the Buffalo District, Corps of Engineers assessment of the structural adequacy of the stone revetment at the R.E. GINNA plant in accordance with the Statement of Work for CERCWINNA Nuclear Power Plant Document No. 50-244. The separate business Letter Report, as required by Work Requirement "E" of the Statement of Work, will be forwarded in the near future. If you have any questions concerning, the con-tent of this Letter Report, please contact Mr. Richard Gorecki (FTS 473-2230) of my Coastal Engineering staff.

Sincerely, 3 Incl GEO . JOHNSON 1 ~ Plates 1-6 Colonel, Corps of Engineers 2 ~ Exhibits 1-6 Commanding

3. Appendix CF:

Mr. N. Parker U.S. Army Coastal Engineer Research Center Kingman Building Fort Belvoir, VA 22060 NRC Contracting Officer, DC J.P. Knight, DE U.S. Nuclear Regulatory Commission U S. Nuclear Regulatory Commission Washington, DC 20555 Washington, DC 20555 Director, Division of Engineering Mr. B.L. Grenier ATTN: C. Poslusny U.S. Nuclear Regulatory Commission U.S. Nuclear Regulatory Commission Washington, DC 20555 Washington, DC 20555

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Coastal Engineering Research Center Interagency Agreement No. NRC-03-81-110 Proposed Work Directive 1 STATEMENT OF WORK FOR CERt:

GINNA NUCLEAR POWER PLANT DOCKET NO. 50-244 II. ~Bk 1 One high priority activity in NRC is an ongoing systematic safety evaluation of operating nuclear power reactors with respect to current licensing requirements and state-of-the-art technology. At one operating reactor site, GINNA (Docket No. 50-244) on the southern shore of Lake Ontario, a site visit has resulted in questions related to the adequacy of the existing rock revetment along the lakeshore. In particular, portions of the revetment on the west side of the discharge canal appeared to have been degraded in terms of the number and sizes of stones in several..locations. Subsequent to discussing the subject with the licensee, the NRC staff was informed that adequate rock had been provided.

The NRC staff has reviewed the design of the revetment, the flood design bases therefore, and the consequences of failure during a severe storm event shouTd the rock not be adeq'uate. The staff's assessment indicates the original revetment design was adequate.

The licensee's design and potential deficiencies have been documented in the following material, copies of which are attached:

1. Hydrologic Engineering Safety Review for R. E. Ginna Nuclear Generating Plant.

2. Rochester Gas and Electric Corp. Comments on NRC's Hydrologic Engineering Safety Evaluation, January 28, 1981 and May 1, 1981.

3. NRC Response to RGKE Comments on Hydrologic Engineering Safety Review, March 3, 1981.

4. RG8E Drawing Numbers 33013-171 and 33013-5IE, Plan and sections of Ginna Revetment.

Be ~0b'eCtire The objective of this work directive is to obtain from the Coastal Engineering Research Center a technical opinion of the adequacy of the existing revetment at the GINNA site, and to suggest ways that the revetment may be readily repaired if not found adequate.

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C. Work Re uirements Subtask 1 You are requested to review the attached material, visit the site, observe the revetment and review any technical specification the licensee has developed to provide for revetment inspection and maintenance.

Subtask 2 Upon completion of your visit, and no later than December 31, 1981 you should provide a brief letter report that fully addresses each of the following:

a~ The extent to which the existing revetment presently conforms to the design. Included should be .identification of the location of any areas .

which do not contain rock of acceptable size or gradation.

b. If the conclusion is that the revetment is not adequate, identify the extent of nonconformance in terms of numerical estimates of areas and rock volumes of different rock size ranges or categories and practical ways in which design adherence can be achieved.

c. Identify licensee representatives views on a and b above.

d. Identify the anticipated durability and survivability of the revetment for the next 10 years, 20 years and for longer periods under the existing or proposed, technical specification.

D. Level of Effort and Period of Performance The anticipated level of effort is approximately two-man weeks over three months: The entire work directive is to be completed by December 31, 1981.

E. Re ortin Re uirements At completion of task 2 a letter report, as described, is to be submitted to the Project Officer with copies to: the NRC Contracting Officer, DC; the Director, Division of Engineering, NRR, ATTN: C. Poslusny; J. P. Knight, DE, NRR; and B. L. Grenier, NRR. A separate business letter report is to be prepared with copies to the same individuals. This report is to contain:

a. a brief summary of the. work performed;

b. estimates of total funds expended for 1) manpower, 2) computer services, 3) travel and 4) miscellaneous;

c. any problems or delays encountered.

4 NOTE: Cost information for each plant must be gathered by the.NRC as a legal requirement to properly, assess licensing fees to the utilities.

F. Meetin s and Travel A site visit of one professional employee to observe the revetment and have technical discussions with the licensee will be required. The trip will be 1 to 2 days in duration.