ML19256F043
| ML19256F043 | |
| Person / Time | |
|---|---|
| Site: | LaSalle  |
| Issue date: | 11/06/1979 |
| From: | Bivins W, Johnson T Office of Nuclear Reactor Regulation |
| To: | Hulman L Office of Nuclear Reactor Regulation |
| References | |
| NUDOCS 7911210031 | |
| Download: ML19256F043 (5) | |
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UNITED STATES
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Docket Nos. 50-373 and 50-374 NOV 0 61973 MEMORANDUM FOR:
L. G. Hulman, Chief Hydrology-Meteorology Branch, DSE FROM:
W. S. Bivins, Leader Hydrologic Engineering Section, HMB, DSE T. L. Johnson, Hydraulic Engineer Hydrologic Engineering Section, HMB, DSE
SUBJECT:
SITE VISIT TO LASALLE NUCLEAR POWER PLANT On October 23, 1979, we visited the LaSalle plant to view and evaluate the condition of the riprap protecting the cooling lake embankments and service spillway. We were accompanied on the visit by personnel of the. applicant, his representatives, and the Region III Inspector, John Neisler. A list of attendees is attached.
BACKGROUND The riprap, related to the safety of the facility, has been subject of continuing consideration since the OL application. The pr'ncipal issues have been with regard to the in-place gradations and. thickness af the riprap layers.
Earlier visits had identified the following issues:
On June 26, 1978, NRR visitors G. Turi and R. Gonzales noted that the maximum size. stone on the. service spillway was too large based upon the applicant's approved r;radation, llany stones were larger than the layer thickness. This is not good engineering practice, because of the result-ing voids. Additionally, a shortage of intermediate and small stone prevented adequate interlocking of the stones. Subsequently, the applicant confirmed the NRR staff observation and committed to break down the larger stone and correct the gradation.
On September 18, 1979, NRR visitor T. Johnson, during the Carroll County alternate site visit, noted that large voids existed in the service spill-way riprap. The voids appeared to be caused by the. removal of large stones with no subsequent replacement. Additionally, riprap failure was noted on the east levet. The failure consisted of the dislocation of stone from above the water line,.to the underwater wave beach, due apparently to the lack of interlocking associated with the uniform size of the stones.
Additionally, the small rocks of the bedding layer were exposed.
13/5
?S1 7 911210 0 3 Y $
NCY 0 61973 L. G. Hulman.
SITE VISITS Following an initial briefing we toured the site, visiting the service spillway and made several stops along the levee.
Servic. Spillway - The spillway showed extensive signs of. rework. Large quantities of fine graded material covered the original layer and pre-vented significant visual inspection of the stone gradation, thickness, and size. At one location we removed a small amount of stone to assure that there were larger stones below. The applicant stated new riprap have been placed on the spillway. Further they stated that this.new material was of the proper gradation. The source of the fine graded material was identified as the remnants of a protective blanket placed over the nearby paved road during repair work on the. spillway and from fines which usually accompany the loading of each truck. During sub-sequent briefings the applicant committed to a field test program wherein actual measurements would be made to determine the thickness and gradation of the stone on the service spillway.
Reservoir Embankment - The reservoir embankment on the east side of the cooling pond was inspected. The northern half of the embankment showed signs of extensive rework. The repaired slope consisted of newly placed stone mixed with some previously existing stone. Visual inspection indicates a.high degree of interlocking with excellent gradation. The previous cover, of essentially uniform sized stones, had been.placed upon the wave beach and their original location had been replaced with some new material. The southern half of the east embankment still showed signs.of wave damage. The conditions discussed in the background still exist. During subsequent discussions with the applicant a commitment was made to complete the placement of stones within 6 to 8 weeks on the southern portion of the east bank.
Based upon our. survey we conclude that the material being placed on the east bank provides adequate protection for the embankment and serves the function of a well-engineered riprap layer. A final conclusion based upon the adequacy of the service spillway will await submittal by the applicant of the.results of their inplace testing. This testin is expected within 4 to 6 weeks.
tn W. S. Bivi s, eader Hydrologic Engineering Section Hydrology-Meteorology Branch, DSE dh c=
T. LLJohnson, H ic Engineer Hydrologic Engineering Section Hydrology-Meteorology Branch, DSE
Enclosure:
As Stated 13/5
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L. G. Hulman.
ec: w/ enclosure John Neisler, Region III A. Bournia W. Kreger
- 0. Parr T. Jobnson W. Bivins 13/S
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LIST OF ATTENDEES R. T. Rose CEC 0 T. Quaka CEC 0 M. J. Morris CECO L. J. Burke CECO W. S. Bivins NRC T. L. Johnson NRC E. R. Weaver S&L D. Siefken S&L J. Neisler NRC Region III 13/S
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Mr. D. Louis Peoples Director of Nuclear Licensing Commonwealth Edison Corpany P. O. Box 767 Chicago, Illinois 60690 cc: Richard E. Powell, Esq.
Isham, Lincoln & Beale One First National Plaza 2400 Chicago, Illinois 60670 Dean Hansell, Esq.
Assistant Attorney General State of Illinois 188 West Randolph Street Suite 2315 Chicago, Illinois 60601 Mr. Roger Walker, Resident Inspector V. S. Nuclear Regulatory Connission P. O. Box 737 Streator, Illinois 61364 I3/S
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