ML19208C979
| ML19208C979 | |
| Person / Time | |
|---|---|
| Site: | Pilgrim, 05000471, 05000472 |
| Issue date: | 06/08/1979 |
| From: | Johnson T Office of Nuclear Reactor Regulation |
| To: | Hulman L Office of Nuclear Reactor Regulation |
| References | |
| NUDOCS 7909270714 | |
| Download: ML19208C979 (1) | |
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Docket Non. 50-293 JUN 0 8 073 I
11E!!0RANDUM l'OR:
L.
G. llu l n an, Chief Ilydrology-McLeorology Branch, DSE FROM:
T rry L. Johnson, ilydraulic Engineer llydrologic Engineering Section
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llydrology-Meteorology' Branch,rDSE m
Ti!RU:
Willlam S.
1;ivins, Leader
[U U llydrologic Engineering Section I
. liydrology-Meteorology Branch, DSE
SUBJECT:
SITE VISIT TO PILGRIM NUCLEAR POWER PL/ TNT i..
On April 27, 1978, the NRC alterr. ate site review team conducted a i
site visit at Pilgrin Station.
The purpoce of the visit was to view the site so that it could be compared with alternate sites presented hy by Boston Edison Company (BECo).
This was accomplished.
I noted one feature which could have potential safety implication.
I noted that the breakwater and shoreline south of the plant had suffered some storn damage.
I was told by BECe personnel thit the datage occurred L
during the February storb (the same rtorn that produced 36" of snow in sone locations near Boston).
The btcakwater had been danaged -
apparently by wave action.
The armor stone had been displaced such that r r.:p about 30 feet long existed in the breakwater.
The breakwater is necessary to protect the safety-related plant intake structure (Unir 1)
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from severe wave action.
This intake is necessary to assure adequate f
cooling water to the plant.
BECo personnel told ne that the damage to N
the breakwater was not considered to be a reportable incident to 1&E.
bf This matter was not discussed any further, h.'
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Terry
. Johnson, liydtjuflic Engineer
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Ilydrold>gic Engineering Section p'.
Ilydrology '.eteorology Branch, DSE
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- 11. Denton L. lhilman R. Architz 1, I&E Local PDR D. Muller W.
Divins E. Lecitr i
R. Denise
'f. Ippolito ACRS (18)
- 0. Parr J. llannon NRC PDR f
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f..o ly Docket f!os. 50-293 and 50-471 J M 2 "-._,9
.a MEMORAliDUM FOR:
Olan D. Parr, Chiui Light Water Reacters Cranch a3, DPM Thomis A. Ippolito, chief Operating Reactors dranch #3, DDR FROM:
L. G. Hulman, Chief flydrology-Meteorology Branch, DSE
SUBJECT:
PILGRIM NUCLEAR GEUERATitlG STATION - REPORT ON BREAKWATER DA" AGE Attached is a report on the subject breakwater prepared by W. Bivins and T. Johnson of the Hydrologic Engineering Section.
As a result of the recurring danage sustained by the breakwater, we are recommending the following specific actions:
1.
The licensee for Unit i should be advised that conce.itrated localized damage to the breakwater is not consistent with the bases on which the design was accepted.
Further, additional informational needs are identified in the report and the licensee should be requested to res-pond to those issues.
2.
The Licensing Board for Unit 2 should be notified of the possible degradation of the breakwater.
Concurrently, i.Fe Board should be advised that the applicant has committed to submit the final design analyses for the Unit 2 intake structure for our review and approval prior to commencement of construction of the Unit 2 intake structure (Section 2.4.2 of the SER).
Therefore, any safety implications of the breakwater will be reflected during our review of the final design of the Unit 2 intake structure.
We will help in the preparation of the Board Notification and with any further clarification necessary for the Licensee as requested.
L.w,
. G. Hulman, Chief Hydrology-Meteorology Branch Division of Site Safety and Environmental Analysis
Enclosure:
As Stated 4
3jg cc: See next page mh U I,*-
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Olan D. Parr JU.'; '? 3 079 Albert Schwencer I
cc: w/ enclosure:
J. Davis, ILE B. Grier, ILE
- 11. Denton
. D. Iluller D. Vassallo W. Kreger L. Ilulman W. Bivins R. Jackson V. Benaroya G. Knighten W. Gammill E. Licitra J. Hannon T. Johnson SA BCs R. Architizil, 1&E ACRS(17)
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PILGRI:< fiUCLEAR CET;EUATlf;G STATION REPORT G'i CP,EAKWATER DAMAGE 1.
IliTRODUCTION This report presents staff findings and recomendations regarding t'he damage to the breakwater at Pilgrim f;uclear Generating Station.
The problems which are identified and discussed below regarding the break-water damage may have safety implications at Unit I and licensing implications for Unit 2.
II.
BACKGROUtiD ThebreakwateratPilgrimStationwasprohidedtoprotecttheonshore, safety-related Unit 1 buildings, including the intake structure where the service water pumps are located. Thebreakwaterwillalsoprohideprotection for the proposed Unit 2 intake structure. This is accomplished by causing largeandpotentiallydamagingwahestobreakoffshoreonthebreakwater, rather than ct the intake structure. The intake structure is designed to resistresidualwaheactihityassociatedwiththepresenceofthebreakwater.
The design of the breakwater was based on physical hydraulic model tests, donductedbyBechtelCorporationattheUnihersityofCaliforniaatBerkely.
These tests indicated that a stable breakwater section could be provided with about 6% damage occurring to the breakwater during design conditions.
The stability criteria of 6% damage was selected based on the overall breakwater integrity, rather than the stability of any individual armor unit.
Displace-ment of random stones will not seriously weaken the strength of the breakwater 1041 320
. structure as a whole, nor adversely effect the' ability of the breakwater to serve its safety function. Some damage was, therefore, expectt d to occur, consisting of minor displacement of individual capstones on the outer layer of the breakwater.
During the winter of 1978, damage occurred to the breakwater as a result of a severe northeaster (See June 8, 1978 memo T. Johnson to L. Hulman, enclosed). The damage consisted of expected minor displacement of some capstones, but unexpected concentrated damage to a portion of the breakwater also occurred.
It was concluded at the time of the isolated damage that repair of break-water would be adequate, so long as the repairs were completed in a timely manner. No further problems were expected.
However, additional damage occurred to the breakwater during the winter of 1978-1979 (See site visits memo T. Johnson to L. Hulman, June 19, 1979, enclosed.) The most severely damaged portion of the breakwater was once again a large gap - approximately 30' long x 20' wide x 10' deep.
This damage and the damage configuration (i.e., a complete section was removed from breakwater) were not expected. As previously stated, during near design basis conditions only minor generalized rock displacements are expected to occur, not removal of localized sections of the breakwater.
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r III.
DISCUSSIO!i The 1978-i979 damage raises serious questions'as to the adequacy of the breakwater to withstand wave forces due to severe storms.
In particular, sincelargelocalizedportionsofthebreakwatercanberemohed,thereis no assurance that the safety-related intake structure will be adequately protected from severe wave activity.
WehaYebeeninformallyadvisedthattheLicenseehasconcludedthatthe percent of damage to the breakwater is consistent with the limits accepted by the staff during the safety review of Unit 1.
The accepted damage limit is 6 percent.
The licensee apparently concludes the damage, although local in nature, is acceptable because it constitutes less than 6 percent of the breakwater length or volume. We conclude this conclusion is inconsistent with good engineering practice.
While damage to breakwater is anticipated in the design, the damage is assumed to be generalized in nature. Under no circumstances is localized, essentially complete, failure of a breakwater cross section anticipated or acceptable.
At the present time, the reason for the breakwater inadequacy is not known.
The design of the break ater was based on model tests performed by the lic2nsee and his consultants.
Reasons why the breakwater has failed may incl'ud'e one or more of the following:
a) The.model testir g program (on which the breakwater design was based) inadequately identified the magnitude and duration of forces involved, 1041 322
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b) the test results were not adequately reflected in the prototype design, and c) the prototype breakwater was not constructed as designed (i.e.,
in a manner similar to the model with regard to rock size and configuration).
IV.
C0f1CLUSI0flS Af!D REC 0fMEtiDATI0t;S Based upon the two consecutive failures of the breakwater, there are serious questions as to the capability of the breakwater to protect the intake structure during severe storm events. At this time there is inadequate information and data for the staff to independently determine the cause of the failures. Therefore, the licensee for Unit 1 should be requested to submit to the fiRC staff the following design and construction information:
a.
photographic documentation of the existing and damaged breakwater, b.
detailed descriptions of the damage which occurred in the winters of 1978 and 1979.
c.
as-built drawings of the breakwater.
d.
the results of field neasurements and weighings to determine average rock size.
e.
additional discusiion and evaluations of the model studies to support the adequacy of the prototype breakwater designs, f.
a summary report comparing the model testing to the prototype design, and constructed breakwater.
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an evaluation, with bases, for why the breakwater failed.
h.
descriptions of proposed surveillance and repair procedures to be implemented for future maintenance of the breakwater.
In lieu of the above inforr;. ion, an analysis cot. a be submitted documenting the capability of the intake structure and shoreline revet-ment to resist design wave forces and flooding in the complete absence of breakwater.
If the capability of the intake structure cannot be so documented, it would also be acceptable to document that consequences of flooding and intake structures and revetment failures do not exceed the 10 CFR 100 guidelines. This information should be submitted as soun as possible.
We understand that rephirs to 1979 damaged portions are currently under-way, with completion expected in about four weeks. This is considered to be an adequate first step in proving the capability of the breakwater.
We recommend that the licensing board for Unit 2 be notified of the potential prcblem regarding the stability of the breakwater.. Concurrently, the Board should be adhised that the applicant has comiitted to submit the final design analysesfortheUnit2.intakestructureforourreYiewandapprovalprior to coninencement of construction of the Unit 2 intake structure (Section 2.4.2 of the SER). Therefore, any safety implications of the breakwater will be reflected during our review of the final design of the Unit 2 intake structure.
In addition, the Unit 2 intake structure can be designed to withstand the design basis flood forces without credit for the effects of the breakwater.
1041 324
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%, v*....f JUN 1 9 1979 MEMORANDUM FOR:
L. G. Hulman, Chief Hydrology-Meteorology Branc.), DSE FROM:
T. L. Johnson, Hydrologic Engineering Section Hydrology-Meteorology. Branch, DSE W. S. Bivins, Leader, Hydrologic Engineering Section M//
THRU:
Hydrology-Meteorology Branch, DSE
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SUBJECT:
SITE VISITS TO PILGRIM liUCLEAR PLAllT BREAKWATER AND
SUMMARY
OF BREAKWATER CONDITIOls On June 1,1979, I accompanied Ralph Architzil, Regicn ! I&E, on an unannounced inspection of the subject breakwater.
The purpose of the inspection was to verify that proper repairs to a portion of the structure damaged in 1978 had been performed.
We walked the entire length of the breakwater. We found one portion of the structure had been severely damaged and that minor damage had occurred at several other places.
Subsequently, Mr. Arc.hitzil stated he was informed by station personnel on June 5,1979, that the severely damaged portion was not the same portion that had received damage in 1978.
The originally damagec portion had been repaired, but additional damage had occurred during winter northeasters in 1979.
I again visited the breakwater with Joe Nicholson, Boston Edison Company,on June 11, 1979. The purpose of the visit was to gather additional informrion and to meet firsthand with scmeone knowledgeable about the storm camage.
Mr. Nicholson told me that the damage developed progressively during several northeasters which had occurred during the past winter. The damage consisted of one large gap in the breakwater about 30' long x 20' wide x 10' deep; this was similar to the failure which had occurred last year.
In addition, several large individual rocks (about 15-20) had been displaced in the vicinity of the discharge canal, along the breakwater, and at the top of br2akwater.
Displacements of smaller " filler" stones had also occurred.
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P00ROPJBIR L. G. Hulman
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JU i 13 573 Mr. Nicholson informed re tha t rt-
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- in one to two weeks. d-gencing on
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T. 1. '..A u. n..,.,c'rclogic Engi;icering Section H,..co l u,y,'a t.c ro ib cy a ranch Divisica of Site Safety and Environ ci al Analysis _
f cc:
D. Muller B. H. Grier, Region I I&E W. Kreger G. Vmighton W. Bivins R. Architzil, Region I I&E T. Johnson L. Heller ACRS (16)
- 0. Parr J. Hannon 1041 326