ML20211F215

Responds to Re Crack or Fissure Mended in Bedrock Located Below Plant in Course of Const.No Ref to Matter Found in Mar 1983 Ser.Pages from SER & FSAR Reviewed & Encl for Info

ML20211F215
Person / Time
Site:	Seabrook
Issue date:	02/18/1987
From:	Harold Denton Office of Nuclear Reactor Regulation
To:	Weddle M NEW HAMPSHIRE, STATE OF
Shared Package
ML20211F219	List: ML20211F215 ML20211F223
References
NUDOCS 8702250005
Download: ML20211F215 (11)

Text

,

FEB 181987 The Hin:rablo Micha31 Weddle N New Hampshire House of Representatives Concord, New Hampshire 03301

Dear Mr. Weddle:

Your letter of January 13, 1987 to Chairman Zech has been referred to me for response. You indicated that one of your constituents reported to you that in the course of Seabrook's construction "a serious crack or fissure was mended in the bedrock located below the plant" and that this is reported in an "NRC Safety Analysis Report." You wanted the NRC to confirm this and to provide you "any pertinent details."

We reviewed Section 2.5.4, " Stability of Subsurface Materials and Foundations,"

in our Safety Evaluation Report (SER) dated March 1983 and found no reference to such a matter as your constituent reports. Section 2.5.4. of the March 1983 SER (and Section 2.4.5. of supplements to the SER) is where one would expect to find any evaluation of such matters. We reviewed the appropriate section in the utility's " Final Safety Analysis Report" (FSAR) and found no specific mention of this. Pages from the SER and FSAR we reviewed are enclosed for yer information (there were no supplements to the SER on Section 2.5.4.).

It may be tell to note that when rock examination is done for siting a plant, very often there is some partially weathered rock that must be removed also.

This is done to assure that siting will be done on fresh, hard bedrock. Usually the place of the removed weathered rock is backfilled with 3000 psi fill concrete. This is standard nuclear plant construction practice and it does not represent a safety harard.

Sincerely, criM ~ W W

a. a. u:/ a Harold R. Denton, Director Office of Nuclear Reactor Regulation

Enclosure:

As stated DISTRIBUTION Docket File

• Tkovak (2)

NRC PDR PD#5 R/F Local PDR VNoonan MBridgers-FD0 2496 VNerses TMurley MRushbrook JTaylor JFouchard, PA TMurray RVollmer/HDenton DMossburg-EDO 2496 SECY 87-65

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• See previous concurrences PDf5:PM PD#5:D PWR-A:ActgD NRY:Jf)

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ADocK 05000443 Pnn

SB 1 & 2 FSAR

( (d) Weathering, Alteration ne bedrock in foundation excavations at the plant site is generally fresh, hard, and unweathered. Weathering is a significant feature only in a 10 to 20 font zone associated with the top of bedrock, coincident with the close jointing found in this horizon, and locally in a small number of joints or faults. All weathered material associated with the bedrock ' surface was removed from foundation areas. Weathering persists along joints, faults, and fractures to some degree in all depths of the excavations. Most of this weathering is slight, and the more severe weathering is intermittent along scattered features which neither individually nor col-1ectively represent significant decomposition of the L, . bedrock.

Weathering or alteration of site bedrock is insignificant, and represents no hazard to plant structures.

(e) Cavernous, Unstable Lithologies No cavernous or unstable materials comprise any portion -

of the bedrock in site foundation excavation.

(f) Unrelieved Residual Stress A report on measurement of in-site horizontal stresses in the Newburyport pluton at the plant site is presented in Appendix 2H. nese measurements were taken between elevations -2 and -12 (MSL) at depths of 30 to 40 fee Q elow the bedrock surface. The measured stresses are generally comparable in magnitude to those previously measured in the New England region. No instances of rock behavior suggesting the presence of inordinate unrelieved residual stresses were observed during the excavation of rock for deep foundations of plant structures.

2.5.2 Vibratory Ground Motion 2.5.2.1 Seismicity

a. Local and Regional Seismicity i

l A cumulative seismicity map, inclusive of all pertinent data avail-

able as of June 1979, is presented on Figure 2.5-30. Circles

! with radii of 50,100 and 200 miles from the site have been superimposed for ease of reference. Thresholds of intensity greater than III(MM) and magnitude greater than 3.0 have been used in this compilation.

All available parameters for each earthquake are listed on Table

( 2 . 5 -5 . A separate listing of events with dubious origin or .

p 2.5-81

'y. i(

1 l least one end in the excavation, and many are of limited vertical extent. Dis- i They appear to be controlled by pre-existing joints or foliation planes.

placements range from a few inches to several feet, and sense of movement is generally normal.

k The applicant has categorized all faults in the excavation into seven sets based ..

on orientations, attitudes, sense of displacement, physical characteristics of the fault, and lithologic relationships. The applicant demonstrated by cross-s cutting relationships with other faults and/or diabase dikes that l By crosscutting relationships and radiometric age dating,Z~ . 1 the a Paleozoic, about the time of intrusion of the Newburyport Pluton (400 mybp), .

and the other during the early Mesozoic at the time of intrusion of the diabase Additional evidence of antiquity was documented by dikes, more than 200 mybp. .

mapping unfaulted Pleistocene sediments overlying the faults.

According More than 100 faults were map, ped in the circulating water tunnels. A

• ~ to the applicant all of these faults have similar orientations, attitudes, and relationships to diabase dikes as the seven sets of. faults mapped in the plant ._

excavations and, therefore, are interpreted to have been formed by the same Staff geologists l.

tectonic mechanisms in the Paleozoic and Mesozoic Eras.

visited the site on several occasions to examine geologic features exposed in excavations, including the circulating water tunnels. Based on its review of i

the applicant's data, the scientific literature, including the results of the  :"

New England seismotectonic study and observations (~ durin E(.~

2.5.4 Stability of Subsurface Materials and Foundations y 2.5.4.1 Geologic Features N.

2.5.4.1.1 General Plant Description As noted above.in this report, the Seabrook site is 2 miles inland from the .

h M

open Atlantic Ocean coast of New Hampshire, about 13 miles south The site is of the Maine d, , .

state line and 1.5 miles north of the Massachusetts state line. J within the Seabrook Lowland section of the New England Physiographic Province. ;I  :

The topography of the Seabrook Lowland section is gently undulating, rising w.

gradually from the seacoast to an elevation of 500 ft approx T inland. The plant site itself is located y of broad open areas of level tidal marshes.

l on an outcrop of bedrock, which was overlain by a thin veneer of glacial till

The outcrop rises out of the tidal marsh at this loca-prior to construction. tion to form a peninsula composed of quartz diorite and include ,.

bedrock.

All of the main seismic Category I structures were founded onTable sound 2.3

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bedrock or on 3000 psi concrete backfill extending to sound s

- b dimensions, and the approximate bearing elevation of each foundation.

l 4

i Electrical ductbanks, five electrical manholes, and service f rock. The finished plant grade has been established at 20 ft above mean sea level (msl). .

2-46 Seabrook SER i - _ _ _ _ . - . .- . - - - - - - ,

i 1

' Table 2.3 Main seismic Category I structures foundation data .i Approximate Approximate l' Main Category I foundation bearing j structures dimension, ft elevation, ft (msl)

Containment structure 153 OD* -40 Containment enclosure 153 ID** -40 a 173 OD i Control building 138 x 90 +18 3 2

Diesel generator building 95 x 90 -20 to +18 Primary auxiliary building 145 x 79 -30 to +3 f Fuel storage building 98 x 98 -21 to +7 -,

Condensate storage tank 64 OD +17 Circulating water pumphouse 114 x 130 -43 j

-43 '!

Service water pumphouse 97 x 80 Service water cooling tower 312 x 61 -12 Intake transition structure 82 x 81 , -49 Discharge transition structure 77 x 77 -62

• 0D = outside diameter j

• • ID = inside diameter u To ensure the protection of plant safety-related structures during the period $

2 of peak probable maximum hurricane surge activity, protective structures--

• including Armor-stone-covered rip-rap revetments, a vertical seawall, and a 1,'

concrete retaining wall--are being placed along the portions of the site perimeter that will be exposed to wave action. ,

f 2.5.4.1.2 Foundation Material '.

Seismic Category I structures are founded either on dioritic igneous rocks, quartzitic metamorphic rocks, or on compacted granular backfill placed over l

competent bedrock. The rocks underlying Category I facilities are not generally subject to deep weathering effects and are not readily soluble or cavernous. The bedrock surface is overlain by relatively thin unconsolidated deposits of glacial till that is, in turn, locally overlain by sandy outwash deposits and thin marine clay. Organic marsh accumulations and sandy beach deposits are the youngest materials in the area. The bedrock in foundation excavations is generally fresh, hard, and unweathered. Weathering is significant only in a 10- to 20-ft zone associated with the top of bedrock.

All surface materials were removed in the area of Category I facilities in l

order to found the structures on competent bedrock, concrete backfill over competent bedrock, or compacted backfill over bedrock.

Unit 1 and some Unit 2 facilities are founded on a gneissoid phase of a quartz diorite intrusive, a hard, durable crystalline igneous rock. The rock consists of a medium to coarse grained quartz diorite matrix enclosing inclusions of Seabrook SER 2-47 l s

.?.

r fine grained diorite. The balance of the Unit 2 foundations are founded on E metamorphic rock consisting of metaquartzite and granulite occurring as an g inclusion in the enclosing igneous mass. The physical, chemical, and mechanical properties of the metamorphic rock are comparable for foundation purposes to

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those of the igneous rock. FSAR Sections 2.5.1 and 2.5.2 contain details of [.

the geologic characteristics of the site bedrock. f f

2.5.4.2 Properties of In Situ Materials .[*

The applicant has conducted investigative programs to determine the engineering properties of the foundation bedrock materials at the site. The programs l included both laboratory and field in situ testing efforts. The reported g; properties were derived from the following field and laboratory efforts y~

accomplished in conformance with the procedures identified or referenced: 7 2

Rock quality designation (RQD) - (Deere, 1968) }-

Permeability of rock - (Geotechnical Engineers, 1974) O Rock density testing - (ASTM

• D-2845) JF

' e --- Unconfined compression - (ASTM D-2938)

Young's Modulus - (ASTM D-3148) ~

i Shear Modulus - (calculated)

Poisson's Ratio - (ASTM D-3148)

In situ rock stress - (FSAR Section 2.5, Appendix H) .f.

Rock hardness - (Tarkoy, P. J.) 4 I

2.5.4.2.1 Static Properties i 1

The results of the laboratory unconfined compression tests, Poisson's Ratio 't tests, and rock density tests provided the basis for the applicant's selection 1 of the static engineering properties of the bedrock materials. The range and .}

average of the test results are reported in FSAR Table 2.5-12. The applicant has taken due consideration of the effect of in situ geologic discontinuities ..

existing at the site, as evidenced by the reported range of RQD values of 49

" to 87%, and reduced the modulus values of the intact rock specimen by 90% to ,.

. establish appropriate conservative design properties for the in situ rock mass.

Resultant statically determined properties. representative of the intact rock 'tI i as reported by the applicant include 't j

Density: 2.8 g/cm3 (average) ~j Unconfined compressive strength: 6000 to 34,000 psi 4 Young's Modulus (tangent): 1.3 to 6.3 x 106 psi n" Poisson's Ratio: 0.17 to 0.36 ,

q 2.5.4.2.2 Dynamic Properties l Properties of the foundation rock determined from geophysical surveys are iN discussed in Section 2.5.4.4. 'O k

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• American Society for Testing and Materials {

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Seabrook SER 2-48 l 3

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2.5.4.3 Exploration ii i The applicant has reported that during the period 1968 through 1979 a total of 345 borings and 200 seismic refraction and reflection surveys were done at and in the vicinity of the site. Additional in situ testing included seismic cross-hole and up-hole surveys, in situ rock stress measurements, and water pressure permeability tests. Plate load tests were performed on test fill sections of compacted backfill materials to measure the in situ modulus of the test fill materials. Within the immediate plant site area a total of 112Soil borings were and rock drilled to obtain data on the bedrock and overburden soils.

,I samples were obtained from each of the borings, and the rock core was oriented in many of the borings to determine the strike and dip of joints, fractures, and foliations. Up-hole and cross-hole techniques were used to take compression and shear wave velocity measurements in boreholes in the vicinity of the reactor to obtain velocity data related to the rock mass properties of the bedrock.

The up-hole data were obtained by detonating small charges in Boring B 38, which is adjacent to the Unit I reactor site, and recording at the surface. Cross-L .. hole data were obtained from surveys performed in an array of seven boreholes

.i at the site. Bedrock density values were obtained from representative core samples within the area.

In situ rock stress measurements were performed using the overcoring technique in a borehole drilled adjacent to the Unit 1 reactor site for this purpose. A i series of 11 of in situ borehole expansion measurements were taken during over-coring. The modulus of elasticity of the rock was measured by testing sections of overcored annular cylinders of rock removed from the hole; the magnitude and direction of the largest and smallest normal stresses in the horizontal plane were then computed using the data generated. Results of horizontal compressive stress measurements are in FSAR Section 2.5.4.2.

Additional site geotechnical investigations reported by the applicant include a comprehensive office review of available published reports and geologic maps of the area.

Based on the information presented in the FSAR, the staff finds that the applicant's site investigation covered the site area in sufficient detail to provide a high level of confidence that specific subsurface conditions have been adequately defined. The staff review of the data presented reveals no evidence of significant areas of landsliding, subsidence, uplift, collapse, or solutioning in the vicinity of the site.

2.5.4.4 Geophysical Surveys The applicant has completed a series of compressional "P" wave and shear"S" "S" wave velocity measurements at the site. Up-hole and cross-hole "P" and wave velocity measurements were made at seven boreholes in the~ vicinity of the reactor location. Laboratory sonic testing was also done. Density values used in estimating elastic properties of the in situ bedrock were obtained from rock core samples also taken in the vicinity of the reactor sites. The results of "P" wave velocity these investigations are in FSAR Table 2.5-12. A compressional range of 13,000 to 16,000 fps was measured by the surface seismic procedure. A range of 14,500 to 20,000 fps was measured using laboratory sonic techniques on intact rock cores. Shear "S" wave velocities measured usingThe up-hole and cross-density of the hole geophysical tests ranged between 8000 and 10,000 fps.

Seabrook SER 2-49

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rock core specimens tested ranged between 2.63 and 3.01 g/cm. The Poisson's Ratio calculated using "P" and "S" wave values obtained from up-hole and cross-hole testing ranged between 0.29 and 0.35. The staff considers these values representative of the igneous and metamorphic rocks of the site area (Jaeger and Cook,1969; Jumikis,1979; and Bowles,1979), and suitable for use in design calculations, as appropriate.

2.5.4.5 Excavation and Backfill 2.5.4.5.1 Excavation I

Excavation in soil overburden and rock was required at the site to establish the planned foundation grade for plant structures. Overburden was removed by

, conventional means. Rock excavation in partially weathered and sound rock was -

accomplished by controlled blasting and was nominally vertical, except where joint patterns and bedding planes controlled. After excavation, all bedrock surfaces were thoroughly cleaned, inspected, and mapped in detail by qualified _

'L. geologists. FSAR Figure 2.5-15 is a summary map of si w bedrock geology. A thorough discussion of the geology of exposed site founcation excavation is in FSAR Section 2.5.1.2.b.6. Areas of overbreak or of overexcavation to remove -

weathered rock were backfilled with 3000 psi fill concrete produced and tested in accordance with seismic Category I structural concrete procedures. Because

~the calculated maximum expected rock heave at the bottom of the reactor excava-tions was less than 0.25 in., the applicant did not implement a rock movement monitoring program. The applicant reports that no instances or evidence of -

rock behavior or foundation movement attributable to heave were observed during construction.

2.5.4.5.2 Backfill 3

The applicant has reported that approximately 500,000 yd of engineered back-fill were used under and around all seismic Category I structures in safety- '.f 4

related areas. An additional 500,000 yd of engineered backfill and random 3

fill material were used in nonsafety-related areas. Five types of engineered i backfill materials were used, as described below. /:

(1) Fill Concrete: Fill concrete batched to attain a 28-day compressive A strength of 3000 psi was placed under all seismic Category I structures except 1' ductbanks, manholes, and service water piping runs from the top of sound bed- ',.

rock to the bottom of the structure. Locations and typical depth of place-

~

ment of fill concrete are shown in FSAR Figures 2.5-42 through 2.5-42d. Ag-gregates conformed to ASTM C-33. Portland Cement conformed to ASTM C-150 ,

s Type II. Concrete samples were taken in accordance with ASTM C-172, and cylinders were made in accordance with ASTM C-31. Compressive strength was tested in ac- ('

.y cordance with ASTM C-39. The minimum 28-day strength reported by the applicant  ;,.

was greater than 3000 psi, and the minimum 90-day strength was greater than "'

5000 psi.

(2) Backfill Concrete: Backfill concrete proportioned to have a 28-day com-pressive strength of 2000 psi was placed between rock excavation walls and "

structure walls below the bedrock surface for all seismic Category I structures.

Typical sections for placement locations are shown in FSAR Figures 2.5-42 ff '

'1 through 2.5-42d. All backfill concrete conformed to the same standards as fill x

V Seabrook SER 2-50 M

/

The Hon:rablo Micha21 Weddla New Hampshire House of Representatives /

/

Concord, New Harpshire 03301

Dear Mr. Weddle:

j/

/

Your letter of January 13, 1987 to Chairman Zech has been referred to rpe for response. You indicated that one of your constituents reported to you that in the course of Seabrook's construction "a serious crack or fissue/was mended in the bedrock located below the plant" and that this is reported in f an "NRC Safety Analysis Report." You wanted the NRC to confirm this and'to provide you "any pertinent details." ,/

We reviewed Section 2.5.4, " Stability of Subsurface Faterial's and Foundations,"

in our Safety Evaluation Report (SER) dated March 1983 and' found no reference to such a matter as your constituent reports. Section 2'5.4. of the March 1983 SER (and Section 2.4.5. of supplements to the SER)'is where one would expect to find any evaluation of such matters. We reviewed the appropriate section in the utility's " Final Safety Analysis Repo'rt" (FSAR) and found no specific mention of this. Pages from the SER and,FSAP we reviewed are enclosed for your information (there were no supplements to the SER on Section 2.5.4.).

p Itmaybewelltonotethatwhenrockexaminationisdoneforsitinoaplant, rock that must be removed also.

very This isoften done there is some to assure thatpartially siting willweathere[done be/ on fresh, hard bedrock.

Usually the place of the removed weathered rock is backfilled with 3000 psi fill concrete. This is standard nuclear plant construction practice and it does not represent a safety hazard, incerely,

/

/

Harold R. Denton, Directer Office of Nuclear Reactor Regulation

Enclosure:

/

As stated /

DISTRIBUTION Docket File TNovak (2)

NPC PDR PDf5 R/F Locd1 PDR VNoonan MBiidgers-EDO 2496 VNerses TMurley MRushbrook

/JTaylor

, TMurray

/ RVo11mer/HDenton

/ DMossburg-ED0 2a96 SECY 87-65 f

• See' previous concurrences b PD#5:PM rD#5:D PyM,- :ActgD NRR:DD NRR:D

• VNerses:ss *yNoonan TN(.vak ?Yo11mer HDenton

!2/4/87 Ub/8) 2ll0(87 2/ /87 2/ /87 f

r o ,

The Honorable Michael Weddle hew Hampshire House of Representatives Concord, New Hampshire 03301

Dear Mr. Weddle:

Your letter of January 13, 1987 to Chairman kch has been referred to me for response. You indicated that one of your constituents reported to you that in the course of Seabrook's construction "a serious crack or fissue was mended inthebedrocklocatedbelowtheplant"andthatthisisreportedinan"NRg Safety Analysis Report". You wanted the NRC to confirm this and to provide you "any pertinent details".

/

/

We reviewed Section 2.5.4, " Stability of Subsurface Materials and Foundations",

in our Safety Evaluation Report (SER) dated March 1983 and found no reference to such a matter as your constituent reports. Section 2.5.4. of t)d March 1983 SER (and Section 2.4.5. of supplements to the SER) is where tofindanyevaluationofsuchmatters.Wereviewedtheappropr)a,onewouldexpect te section in the utilities" Final Safety Analysis Report" (FSAR) and found,no specific mention of this. Pages from the SER and FSAR we reviewed are enclosed for your information (There were no supplements to the SER on Se'ction 2.5.4.).

It may be well to note that when rock examination is dor; for siting a plant very of ten there is some partially weathered rock that inust be removed also.

This is done to assure that siting will be done on f h, hard bedrock. Usually the place of the removed weathered rock is backfille with 3000 psi fill concrete. This is standard nuclear plant construct' ion practice and it does not represent a safety hazard. /

/

/

/

Parold,5.Denton,Direc'for Offics of Nuclear Reacto' Reoulation DISTRIBUTION Docket File or Central File P 5 DIR:PD/5 DIR:DIV NRC POR w/cv of incomino :ss VSNoonM< TNovak I.ocal PDR W[cy of incoming /2/ /87 2/h/87 2/ /87 ED0# 2496 '

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PPAS (ED0#2496)w/cv of incoming Division Director /Secy (2)

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PD#5 Green Ticket File V.Nerses/

V. Noonan' T. Novak R. Vollmer P.,Denton T( Purley

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'!.( 'o,, UNITED STATES a o NUCLEAR REGULATORY COMMISSION - -

N WASHINGTON, D. C. 20555 .f 8 0E (, -

EDO PRINCIPAL CORRESPONDENCE CONTROL FROM: DUE: 02/11/87 EDO CONTROL: 002496 DOC DT: 01/13/87 MICHAEL WEDDLE FINAL REPLY:

STATE REPRESENTATIVE STATE OF NEW HAMPSHIRE TO:

CHAIRMAN ZECH FOR SIONATURE OF: ** GREEN ** SECY NO: 87-65 DENTON DESC: ROUTTNG:

CONSTITUENT CONCERN RE SAFETY AT SEABROOK MURLEY TAYLOR DATE: 01/28/87 MURRAY ASSIGNED TO: NRR CONTACT: DENTON SPECIAL INSTRUCTIONS OR REMARKS:

NRR RECEIVED: 1/29/87 _ _.

ACTION: {_ DPLA:tOfAK; NRR ROUTING: DENION/VOLLMER PPAS MOSSBURG

?. . . ' -

OFFICE OF THE SECRETARY CORRESPONDENCE CONTROL TICKET PAPER NUMBER: CRC-87-0065 LOGGING DATE: Jan 23 87 ACTION OFFICE: EDO AUTHOR: M. Weddle AFFILIATION: NH (NEW HAMPSHIRE)

LETTER DATE: Jan 13 87 FILE CODE: ID&R-5 Seabrook

SUBJECT:

Constr at Seabrook's nuc facility--req copy of NRC Safety Analysis Report ACTION: Direct Reply DISTRIBUTION: Docket SPECIAL HANDLING: None NOTES:

DATE DUE: Feb 6 87 SIGNATURE: . DATE SIGNED:

AFFILIATION:

nt:'d (tlt. EDO l' '

}

Date Time F 11 1

EDO - 002496 l

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