ML19332A915
| ML19332A915 | |
| Person / Time | |
|---|---|
| Site: | Summer  |
| Issue date: | 09/02/1980 |
| From: | Tedesco R Office of Nuclear Reactor Regulation |
| To: | Nichols T SOUTH CAROLINA ELECTRIC & GAS CO. |
| References | |
| NUDOCS 8009180569 | |
| Download: ML19332A915 (12) | |
Text
.
~
o nsa
,{pe uq[o, UNITED STATES f '$ w j
NUCLEAR REGULATORY COMMISSION wAsmNaTou, o. c. 2csss
, c-t
'%. )'.
- September 2,1980 Occket No. 50-395 Mr. T. C. Nichols, Jr.
Vice President & Group Executive Nuclear Operations South Carolina Electric & Gas Ccmpany Post Office Box 764 Columbia, South Carolina 29281 Cear Mr. Nichols:
SUBJECT:
REQUEST FOR ADDITIONAL INFORMATION - VIRGIL C. SUMMER NUCLEAR STATICN, UNIT NO.1 Enclosed are requests for additional information concerniag the effects of settlement of the pumphouse and service water intake structure.
These requests numbered 362.15 thrJ 362.49 were developed by the Hydrologic and Geotechnical Review Branch.
Please provide ycur responses not later than September 26, 1980.
If you cannot meet that schedule or require clarification of any of the requests, please contact the staff's assigned licensing project manager, Sincerely, W
Robert L. Tedesco, Assistant Director for Licensing Division of Licensir.g
Enclosure:
Request for Additional Information cc w/enci:
See next page 800918 88f
Mr. T. C. Nichols, Jr. Vice President & Group Executive Nuclear Ooerations South Carolina Electric & Gas Company Post Office Box 764 Columbia, South Carolina 29281 cc: Mr. William A. Williams, Jr.
Vice President South Carolina Public Service Authority 223 North Live Oak Drive Moncks Corner, South Carolina 29461 Troy B. Conner, Jr., Esq.
Conner, Moore & Corber 1747 Pennsylvania Avenue, NW Washington, D.C.
20006 Mr. Mark B. Whitaker, Jr.
40 Group Manager - Nuclear Engineering & Licensing South Carolina Electric & Gas Company Post Office Box 764 Columbia, South Carolina 29218 Mr.
Brett Allen Bursey Route 1, Box 93C Little Mountain, South Carolina 29076 Resident Inspector / Summer NPS c/o U.S. Nuclear Regulatory Ccmmission Post Office Box 1047 Irmo, South Carolina 29063 i.
REQUEST FOR ADDITIONAL INFORMATION VIRGIL C. SUMMER DCCKET NO. 50-395 362.15 As stated in Report No. 2, SWIS Settlement Effects and Related Work, soft / loose surficial soils were removed frem beneath the pumphouse area.
Figure 2, Section Profile of SWIS & PH, (Service Water Intake Structu?2 and Pumphouse) indicated up to 11 feet soft soil was removed. Mcwever, 4
Boring WE-2, showed that the 1cese sandy silt (classified as saprolite) extends to a depth of 17 feet.
It appears that these Icose saprolite were left in place. Discuss their significance en the settiement of the pumphouse.
362.16 The pre-construction subsurface profile of the West Embankment as shewn in FSAR's Figure 2.5-102, indicated that the SWIS & pH are located in a valleyewith seme soft /leese alluvium deposits and icose saprolite.
Have these materials been removed during the ccnstructicn of West Emoankmen:
and 3WIS & pH7 If they were removed, provide the documentation; otherwise, ciscuss the significance of them being left in place.
362.17 In FSAR, Section 2.5.4.5.2, six types of backfill materials were discussed; ncne was called as selected fill. Discuss the relatienship-362.18 Table 1 -f Re;cr No. 2, Inplace Censity Tests of Selected Fill Materials belew El. 390, seemed to indicate tha: seven (7) selected fill materials were used for Nest Emcankment with the cptimum moisture contents varied from 13.5 to 24 5 percent and the maximum dry density vari.ed fr:m 100 to 115 pcf. Exclain new with so few moisture centrol tests performed in the field it can be assured tna: water centents of the placed fill were witnin
- ne limits of -4 and -2 percentage of tne cc:imum meisture centents.
~
i 2
i 362.19 Borin'gs WE-4 & 7, drilled in Sept.1977 (a few months prior to reservoir i
l filling), shewed that the water centents of the c:mpacted fills varied i
l from 19 to 3A ;ercent. These seem to indicate that all fills were placed much wetter than originally preposed. Discuss their significance with regard to the predicted settle:aents.
362.20 Censolidation tests, as stated in FSAR Secticn 2.5.4.2.2, were performed in general accordance with ASTM 02435-70. Mcwever, frem the informatien presented en Figures 2.5-114 it appeared that ASTM's standard procedure was not folicwed for those tests. Specifically, ASTM requires that readings shculd continue at least until the slece of the characteristic linear secondary pcrtion of the thickness versus leg of time plot is apparent. Later tests in c:njuncticn with SWIS 1 FH investigation, similar non-conformance of ASTM crocedure, as shcwn in Report No. 2, was also noticed. Previde the justification for making such a procadure change.
Also discuss the significance of this precedure change affecting the precensolidation pressure, the c:meressicn incex, One cata of consolida:1:n, and the overall settlement estimates.
362.21 Cnly two borings WE-617, were drilled a 'ter tne unexpected cracks were disc 0vered in the intake structure. Ncne wt 1 drilled along er adjacen-to the intake structure. Cens ruction rec rds shcwed tnat several ty es of materials were used at the West Embankment. Provide construction records 1
and field testing results which would enable an as-built section profile including soil pr:perties to be established along tne intake structure.
If the available informatien is not sufficient, :rovide an investigatten program which wculd ;rovice the subsoil profile, ty;e and inickness of f
r s
. various fills, material characteristics, and c:nsolidation characteristics of subsoil and fills.
362.22 Selact fill materials excavated frem barrew source F & G, as stated in FSAR Section 2.5.5.4.3.2, were used for most pertions of the West Embankment and on-site bcrrow soils were used as fill belew elevation 386.0'.
The en-site borrow materials possess a relatively high ccmpressibility as indicated on Figure 2.5-125. There were nine censolidation tests, but no ecmpacticn tests en these on-site borrow material. The censolidatien test results shewn in Figure 2.5-125 gave seme indication that the behavice of those materials are rather ccmplex. Withcut any ccmcaction test data, explain, how the field placement centrol was achieved.
362.23 No consolidation tes: en barrew materials F 13 can be found in FSAR.
Without such tests, explain how the settlements cf these materials were estimated.
362.24 Consolidaticn tests, ~.cformed in 1977 after the discovery of cracks in the intake structure, did not follow the ASTM crocedure. These test results tend Oc over-estimate the preconsolidation pressures.nd uncer-estimate the ccmcressicn indices, therefore, the settlement estimates beccme non-censervative. The results presented in Accendix C of Report No. 2 show the trend of the ccmcacted filis wnen they're subjected to cifferent censolidation pressures. These resuits incicate tha :ne comcressicn indices increased significantly when the saturation pressures were increased. This implies :na more set.lements aculd be expected in the future. Discuss the significance of this cbserved benavice :n antici-pa ed future settlements; quantify ycur discussicn.
l
~
. 362.25 It is not clear hew the revised settlement estimate, as presented in Sec. 6.4 cf Report No. 2, was obtained. Provide the calculation, and the soil profile and prcperties used for that estimate. Also, provide the settlement estimates and back-up data for the SW and NE corners of the pumphouse and the mid-point and east end of the intake structure.
Discuss the significance of the estimated differential settlements, if they exist.
362.25 What are the anticipated future movements for the pumchouse and the j
intake structure.
Identify and discuss their potantial effects.
l 262.27 Borings '4E-6 & 7 r.svealed that the moisture ::ntents of the in-place fill were higher than the 4 percent above optimum limit prescribed in the specification. No rejection or c:ncern was mentioned in the resident engineer's eports attached in Ap endix 5 of Repcrt No. 2.
Occument reports filed with NRC about this ncn-cenformance in construction and hcw resolution was achieved.
262.28 The special testing, presen ec in Section 2.5.6.4.2.3 of FSAR, appears to be trying to justify the acceptability of the ncn-c:nformance mentioned above. Mcwever, the material tested at bcrrew source G, as shown in Table 2.5-592, was not typical fill used. Ma:arials frem bcrrow source
. and en-si a soil were recortedly used to construct the West Emcankment.
The bicek saccles UDS-21 122 were low plastic materials and do not re: resent the materia s frcm source G, as presented in Figure 2.5-122.
t Provide additional backgrounc inf:rmation related to tne s:ecificatien change and the special test: such as the date f:r recuesting such a j.
s:ecifica:fon enange and :ne ia a of cerforming -he s:ecial test, wny i
l
- ne test is necessa /, wny 1:w'biastic material was selected fcr the est, e::.
l g
l w<
,.-_,_,.,wr
-,--..m-
.3 5-
'l 362.29 The summary of 43 gradatien tests frcm the West Emcankment, as shown in Fig. 2.5-142, revealed that select fill was ne: in confermance with the prescribed gridation limits. Discuss tne significance of this, specifically, In the case where materials with more fines than specified were placed.
362.30 Many of the resident engineer's re;crts, ; resented in Acpendix 3 of Report No. 2, stated that soft and organic materials were encountered during censtruction. However, ncne of the reports indicated that prebing was carried cut to determine the extent of the undesirable =aterials.
Occument the removal of these materials. Withcut such dccumentation, discuss the possibility of those materials being left in place, the effect of this error, and the significance to foundation benavior.
352.31 Ground surface elevations of 3crings WE-1 through 5 were not ecmpatible with the centeurs shown en Figure 1 "Locat on Plan, SWIS & ?H" of Recert No. 2.
Clarify this wi:h resciutien and discussion and provide a sectienal profile alcng the longitudinal axis of the SWIS 1 PM.
362.32 The intake structure, as stated in Recor: No. 2, was expected to undergo a linear differential se::lemen: with scme essentially rigid body rc:a:icn, based en the geometries of the underlying scils and on the cverburden along its leng:n. Hence, ne significant bending cf the unnel in the icngitudinal direction was anticipated and no longitudinal reinforcement was proviced in the intake structure. Mcwever, our rev'aw cf tne boring information at the SWIS & ?1 area seems to indicate :he boring informaticn was not utili:ec for the design, becausa:
5
=
6-a.
Had informatien revealed by borings Wi-1 through 5 been used in the design, the incomcatibility of their surface elevations with what were shcwn en Fig. I " Location Plan - SWIS & ?H" wculd have been detected and corrected, b.
Assuming the boring locations shcwn en Fig. I were correct, the surface c:ndition would indicate that differential settlenents should be anticipated because the east end of the SWIS is founded en decomposed rock, the midpoint of SWIS en 20 feet of fill, the west end of SWIS and the east end of the ?H cn 15 feet of fill, 7 feet of lease soil, -and 20 feet of saprolite, while the west end of ?H would be en 25 feet of fill and 30 feet of saprelf te. The lead distributien due to the fill or structure alcng the axis of SWIS & PH varied free almost zero at the east end to as much as 70 feet of fill at the west end. A ncn-linear settlement along this axis shcuid have been anticipated.
In additien to tne bcring evidence, the original settlement estimates indicate that 3 to 4 inches was expected : the PH and 1.5 to 2 inches was expected at the east end of the SWIS. With the ?H sitting en : p cf the IS, it is difficult :: uncerstand wny "no significant bending in the icngitudinal direc:fcn was anticipated."
Frevide the design criteria wnich wers' used fer the SWIS & PH:
including i
earth pressures under static anc dynanic leading c nditions and uncer limi:s of differential se::lements.
t 362.33 ACI 318-71, Secticn 10.5 and the Ccde Ccreentary were cited to justify that the greuting of tne cracks as aide as 0.125 inches is a precau:1: nary m.
m
step. Secticn 10.6.4 stated this is not applicable for structure subjected to aggrettive exposure or designed to be watertight. Discuss the applicability a
of dits cede to the SWIS.
362.34 Epexy grout, as stated in Sec. 3.0 of Report No. 2, was used to fill the cracks. Fifteen test ceres of the grouted cracks were recorted takan in Sec. 8.0.F.
What is the design strength of this grout? What were the confirmation test results? Provide those data.
362.35 The maximum crack width observed is stated to be about 1/8 cf an inch.
What was the maximum crack width at the ucper face of the SWIS?
362.36 It appears frem information in Sec. 8.0.0 that tnc cracks were not sealed at the outer faces of the intake structure.
If this is the case, wnat is the assurance tnat this greut is fully and evenly cistributec along the cracks?
362.37 If the u:per ends of the cracks were c:en, discuss One significance of those :cenings, es:ecially tne corrosion as;ects of the exposed reinforcing bars. Shculd there be unde: acted and unfilled cracks thrcugn the SWIS, discuss the effects of the hycrau'lic gradient thrcugn the crack with regard to piping ercsion of the SWIS foundation or cooling cacacity and effects en pu= ping facilities.
362.38 service water pumo discharge itnes, as reccr:ec in Scc. 5.4 Of :ne Final Re: ort, were dis:evered : nave seme misalignmen: requiring re-excavation in arcer to c:nr\\ect the pipes to the FM.
Describe One nature cf -he misalignment: hori: ntal, vertical cvement Or both and the amcun: Of
- ne movements. What was the conditien of the Oi:elines already turied?
Were Oney also misaligned? Cescribe :ne mani : ring :rogram :er#:rmed al:ng
- ne service pi;e lines?
L
8 362.39 Electrical duct banks were recorted in Sec. 5.3 of the final report to have moved dcwnward about 0.34 inches relative to the PH.
It appears that no investigation or menitoring along the duct banks was perforund.
Discuss the possibility of differential settlement along the duct banks and its effects such as causing the duct bank to crack, the potential for corrosion, and water intrusien.
362.40 Analysis assuming a non-linear soil settlement along part of the structure was performed as indicated in Sec. 7.2 of Report No. 2.
a) Provide the analytical ecdel, assumptiens, soil material pre;erties used, and the results of the analysis, b)
If the settlement information presented in Table 3 was used in the analysis, provide the results' correspending to the state of the settlement.
- ) Discuss the residual stresses in the concrete and the re-bars resulting frcm tne excessive differential settlements. Discuss their effects en future perfomance.
d)
If Table 3 information has not been used, revida ycur program to establish the stress conditiens corresponding to varicus settlement conditiens nnd discuss the residual settlement stress effects en the ability of tne structure c also resist design loadings.
362.11 Mari: ental movecents were cbserved at.the Nor:n anc Scuth Dams. Provide additienal details, such as wnere, wnen, hcw much and direction of the movements; anc discuss the cessible causes and the effects of the heri:en a1. movemen s.
=
L
g.
n e
9 i
i 362.42 Horizontal movements of the SWIS & PR and West Embankment were not j
mentioned in the documents reviewed. Sec. 2.5.6.8 of FSAR indicates I
that hori: ental movements were measured at the North and South Dams.
Justify your reasons for not making measurements of hori::ntal movement
~
at the West Embankment.
362.43 Liquefaction potential, as sta:ed in Sec. 2.5.4.3 of F5AR, was evaluated based on Seed's procedure. Discuss the apolicability of that procedure to saprelf tes in light of the highly cc pressible nature of these materials as disclosed by laboratory test results.
362.44 Slope stability analysis was not performed for the West Emcankment, as stated insec. 2.5.4.10.5.1 of F5AR, because the emeankment heignt is lower than the north or south dam. Since the as-built conditiens of the Embankment were different than those original proposed, justify the validity of not perf:rming an analysis of the emoankment. Describe tne effects of the West Emcankment loads on the SWIS & PH that tend to push the SWIS into the valley.
362.45 Dynamic analyses of typical dam secticns of the norta and south cams were performed based en scme labcratory test results. The materials used in construction were quite differen: fecm those tested. Discuss the signi-ficance of tne changed materials.
362.15 For ne Nes: Emcankment, hignly c:maressible materials were used. Dis:uss the dynamic behar/for of these materials, es;ecially seismic induced se :IEments.
=
'~
362.47 For the SWIS & PH complex, discuss the potential differential ground movements resulting from SSE in a vertical and a critical eblique direction and provide the analyticEl results of the effects en this complex.
262.48 Describe the overall inspection pregram related Oc the reservoir including all dams, embankment, SWI3 & PH, duct banks, SW pipeline, and the SW discharge. Since most conclusiens presented in Sec.11.0 of Report No. 2 need to be substantiated, what kind of adcitional monitoring pregram wculd be precosed?
Discuss hcw you will implement R.G. 1.127.
362.49 In reviewing the FSAR Sec. 2.5, seme open items were noticed. For instance, en page 2.5-97, it is stated that soft and loosa fill was encountered and this conditicn is being evaluated and apcrecriate corrective acticn will ce taken as necessary. Provide One resciutien and dccumentatien back-up data for the corrective action taken.
l l
N-
)