ML19242D402
| ML19242D402 | |
| Person / Time | |
|---|---|
| Site: | Bailly |
| Issue date: | 07/16/1979 |
| From: | Carbon M Advisory Committee on Reactor Safeguards |
| To: | Hendrie J NRC COMMISSION (OCM) |
| Shared Package | |
| ML19242D399 | List: |
| References | |
| NUDOCS 7908150063 | |
| Download: ML19242D402 (3) | |
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UNITED STATES w
NUCLEAR REGULATORY COMMISSION
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i ADVISORY COMMITTEE ON REACTOR SAFEGUARCS A
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c S,...,J July ic, 1979 Hencrable Joseph M. 3erdrie Chairean U. S. Nuclear Regulatory Ccenissicn Washington, T 20555
$UBJEC": SA*::Y GENEPAT!NG STAHCN, NUCI.ZAR 1 Cear Dr. Hendrie:
During its 231st meeting, July 12-14, 1979, the Advisory C:enittee en Reactor Safeguards reviewed the de2ign of the pile foundations for the Bailly Generating Station, Nuclear 1, being constructed by de Northern Indiana Public Service Ccapany CCPSCO). Inis catter was censidered by an ACPS Subecenittee at a.eetirs held in Portage, Indiana, near the site, on July 9,1979. During its review, the Cxmittee had the benefit of discus-siens with representatives and consultants of NIPSCO and of the NRC Staff.
The Ccenittee also had the benefit of de documents listed below and of statecents received frca mecters of the public.
In your letter dated June 8,1979, you cade the following recuest:
"Se Ccesission recuests de Cecnittee to identify and address '..e significance (if any) of the ergineering ard safety issues arising frcm use of de shcrter riline.s as cpecsed to de lenger pilings.
3 particular:
(1) is the use of shcrter pilings a significant design charge fr:c de standpcint of engineerirg, ard culd it recuire significant a'.teratien of :$er aspects of te design of de facility; (2) hat differences, if any, acu'd dere be in the safety Of de facilitv. ferendim en teder lenger er shorter pilings are used?"
"'he Ccenittee heard reports en de experience to date relating tc 2e driving of piles at be site, including de exploratcry driving of the 1:nger piles to de till or rock, ce extensive exploratory driving of de shcrter piles into de intertedded sard ard clay layer, and de various tcrings a.d pile past few years.
Se Cec.' -- = a'sc lead tests dat have been nade : var
-"a heard reports en analvses relating to de factors of safety to be provided against various 1:ading ccchinations and to de expected setticents of de structures supported en piles.
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Hencrable Joseph M. Herdrie July 16,1979 Se Ccemittee has identified cnly two potential safety issues arising frem the use of de shorter piles as cppesa to be icnger piles, and has con-cluded that neider of dese will have any effect en de safety of Se faci'.ity if de procedures pecpesed by N PSCO cr required by de NRC 5taf f are fcilewed Se first of these results frmt de fact dat scme of de e:cploratory longer piles were installed with 2e aid of high pressure water jets hich resulted in disturbance of tne soil (chiefly the sand) in 2e interbedded layer. Sis disturbance is li:lited to eniv. a small certien of de fcundatica area at fcur locatiens. Unless recedial measures are taken, the shorter piles driven in these areas might be deficient in lead-bearing capacity.
NIPSCO has pregesed the use of "cccpaction piles" in de areas of disturbed soil to densify the disturbed scil so that it will be able to provide supp r equivalent to that in de other areas. Be NRC Staff believes tnat dis procedure is acceptable, and the Ceccittee agrees, subject to ccepliance with the following procedurec:
1.
DcFloration by borings or by penetration devices to determine the vertical and horizontal extent of de disturted areas.
2.
Cecpaction of the disturbed material by drivirg cecpactien piles.
3.
Verificatien by bcrings or by penetratien devices that all of the disturbed soil has been ecmpacted.
4.
Perfoncing a ccepressien lead test en at least ene prcduction pile in each discurced area to verify its lead-carrying capacity a-d lead-defer atien charac-teristics.
N!?SCO has agreed te tnese procMures.
The seccnd issue resulting frxi de use of the shcr er piles is de,tetential set-lement of d e supported structures. Se settlement af er construction wculd have been expected to be essentia'.ly :ere fcr de icnger pile fcur.daticn.
For e shcrter piles, the set:1 rent has been esti :ated by N!?SCO to be en de crder of we inches. Settleent cf Sis magnitude is a unusual fer a nuclear plant and wculd have no significance :: sa fety, 2e Ceccittee has recccrended to de SRC Staff, hcwever, da: 2e reded cf cal ulating de settlement be reviewed :0 assure dat it has been dcne censarvatively.
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Ecnorab' a Jesep M. Hendrie July 16,1979
- n addition, N:PSCO has pr: posed a program to measure settle.ent at numerous 1ccations on de structures during creration of de plant, and the WC Staff has stated that such reasurecents will be required by 2e Technical Speci:1-cations and that suitably conservative limits en permissible settleents will be established, In view of dese cecmitments, de Ccemittee believes dat potential settlements, even if greater San 2cse new predicted, culd not zepresent a hazard to e public.
T e NRC Staff is centinuing its review of de feu.dat en design, and de Cemittee celieves dat $s re-aining foundatien-related issues, not related to de use of shorter piles, can be resolved by de Staff.
In direct res;cnse to de questions raised bv. v. cu. rec.uest, the AOS believes Sat:
1.
The use of sherrer piling is not a significant design charge ircra the stardpcint of engineeri.q.
2.
Se use of shorter piling aculd not require significant alteration of other aspects of the design of the facility.
3.
Bere will be ro difference in the safety of de facility depending en -teder icnger or shorter pili qs are used if the matters referred to above art treated as now prop sed.
Sincerely,
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yax x. Carben Cairman Oeferences:
'. Prelimi.ary Safety Ar.alysis :.ecort en Eailly Ger.eratics Stati:n, Nuclear 1.
2.
Cu ign Malysis and :nstallation of Criven M-Files F:undati:n, 0,eper: SL-3529, submi'.ted en March 3,1978.
3.
N PSC's c esycnses to.GC Staff.testiens, succitted en July 14, 1979.
4.
2dicator Pile Pr: gram, tutcitted by N!.SCO : NRC n Septencer 26, '978.
5.
Supclenentary Informati:n n Criven H-Pile Foundation, N PSCO, Cecccber 4,
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6.
Letter, 3. 3. 7assallo, NRC, to H. P. Lyle, N:FSCC, June 23, 1979.
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Saf.ly Gereratics Station, Nuclear 1 Constructicn Fe: :it, May ', '.974.
S.
FF,uest by de Por er Ccunty Sapter :f de ::aak Walt:n League Of Ameri:a, Mc., Fectuary 27, 1979.
9.
I.nt:ar, I.
M. Sherb, N PSCO, to C. 3. 73ss21'0, NFC, June 29, 1979.
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