ML17053D667

Safety Evaluation Re Proposed Changes to Revetment Ditch Sys.Use of Proposed Graded Granular Sys Acceptable Alternate to Filter Fabric

ML17053D667
Person / Time
Site:	Nine Mile Point
Issue date:	04/07/1983
From:	NRC
To:
Shared Package
ML17053D666	List: ML17053D665 ML17053D667
References
NUDOCS 8304150010
Download: ML17053D667 (12)

Text

Nine Mile Point Nuclear Station, Unit 2 Docket Number 50-410 Evaluation by NRC Staff - Proposed Changes to the Revetment-

>'+~h Cucking uy:

mando vagat~r.u 1.

INTRODUCTION A revetment-ditch system along the shore of Lake Ontario protects the Nine Mile Point Nuclear Station Unit 2 (NMPHS) from flooding due to Probable Maximum Windstorm conditions in the lake.

The applicant docketed (in 1977) the proposed

design, including results of model

studies, of the revetment-ditch system (Reference 1).

The applicant proposed some changes to the revetment-ditch system and requested approval of the changes from the NRC (Reference 2).

The changes proposed by the applicant were:

1) use of reinforced concrete armor units for the cover layer of the revetment and 2) use of a graded granular filter system in lieu of the filter fabric.

The HRC staff asked for additional information (Reference 3), and the applicant has responded (Reference 4).

The geotechnical staff has evaluated the stability of slopes of the revetment-ditch and the use of a graded granular filter system in lieu of the filter fabric (change 2).

2.

EVALUATION bill Figure 1, taken from Reference 4,

shows a typical cross section of the proposed revetment-ditch at the NMPNS.

The cross-section of the revetment/

breakwater was established by model studies (Reference 1).

The proposed construction stipulates removal of all existing overburden material beneath the revetment-ditch and construction of the revetment-ditch on 8304i SOOi0 830407 A

PDR ADOCK 050004i0 PDR i

j

),

ll r J

~

~

~

horizontally bedded sandstone.

Since the revetment-ditch is founded on bedrock, the stability of the revetment foundation is assured.

The in sitQ soil (lacustrine deposit and till) left in place behind the r

protected land-ward slope of the ditch wHl-not influence the stability of the slope'.

The side slopes of the ditch are 2 horizontal to 1

vertical, and are composed of 75 to 225-pound stones.

The side slopes of the ditch are judged to be sufficiently stable.

Filter Desi n

The original design proposed by the applicant (Reference

1) used a filter fabric as a separation barrier between the natural in situ soil and the stone revetment material.

The applicant-now proposes to use a graded granular filter system instead of the filter fabric (Reference 2 and 4).

The filter system consists of two filters, Filter 81 and Filter P2,

.between the in situ soil and the revetment material.

Figure 2 shows the gradation of the filters and the in situ material.

The staff has checked the gradation of the filters for avoiding migration of soil particles into the filter, minimizing head loss in the system, avoiding segregation within each filter, and avoiding internal movement of fines between the filters.

The proposed graded filter system satisfies jt the above design criteria (Reference

5) for prote'ctive filters and fulfills the function originally intended for the filter fabric.

The filter system proposed by the applicant meets all regulatory requirements and good design practice and iKCherefore acceptable to the staff.

3.

CONCLUSION The NRC-staff has evaluated the changes proposed by the applicant and concludes that:

1.

The proposed slopes of the revetment-ditch will be sufficiently stable to perform their intended function, and 2.

The graded granular filter system proposed by the applicant is an acceptable alternate to the filter fabric.

References 1.

"Final Report - Design and Analysis Method. for Revetment - Ditch System-Nine Mile Point Nuclear Station - Unit 2 - Niagara Mohawk Power Corporation"--

Docket'No.

50-410, August 1977.

2.

Letter from S.

Manno of the Niagara Mohawk.-Power Corporation to A. Schwencer of the NRC, dated September 21, 1982,

Subject:

Nine Mile Point Unit 2.

3.

Letter from A. Schwencer of the NRC to G.

Rhode of the Niagara Mohawk Power Corporation, dated January 27, 1983,

Subject:

Nine Mile Point Nuclear Station, Unit 2, Revetment-Ditch.

4.

Letter from C.

Mangan of the Niagara Mohawk Power Corporation to A.

Schwencer of the NRC, dated February 18, 1983,

Subject:

Nine Mile Point Unit 2.

5.

U.S.

Navy Design Manual - Soil Mechanics, Foundations.

and Earth Structures, NAVFAC DM-7, October 1971.

ELKYATIOH VhhlES CI. DITCH CL ITKVKruKHT LI~TON

/ OI'Ll HATE¹IAI.

KL ISO ~O I

0

~

e v "I n

a OII'I.OV ELof'E fILTEII.!I C-O I Ihl TO¹ Of hEVETUKHT KL RIS) 0 rl'LTE¹ 02 VA¹IEt rh ULI

~

~

MEXk LAIIK LEVEL KL Z4t'-t I

I le a

~-o) i'-0 UIHIUUU x'-a"

=XCAUATION SLOIIt TO AC I 8: IV M FLATTCTC 46 OPECTH)

~

6V THC CVCIKEEIC TTT'ICAL SECT IOH tlEVCTUEHT-OITClt ITOCh KLKYATIOH VA¹IEt KhlfiTIHO IhOUHO IIUhfACE NOICSI fILL

%LZUZC fILL wMww&vv\\y~~~~

WM~O

&&WMOW&WW~

WO LIUITt Of KIICAVATIOH I I

%h

~

~

~

1 M're

~

~ I'tra

~ I a a

v a wo 4

r

~ '\\

~ r ~

/

~+0 g%

~

~

cLcva'IION or Lavt Oasco vrDN V.l LAAC SVAVtv -

I~ SS O*TVU IVLLSI 1, 400

~Irlo SVSICV ~ ASCO DN N'I

'llAIC CDONOINATC STSICU S.

ALL 51 AIIDNS Vt ASVIIC0 AJ.ONO cchlcNLIhc or IItvcIUCHT

~. IIIIS DIIA~lha DOCS hOI INCLUDC ALL FLANI SIIIVCTVAI5 S. t altllho Vailalai'5

~ IINIH TNC Cao ~ 5'StCIION OI'rit atvt fvtNI.DITCH Aht IO St CD CAvalto

~. Ulhlvvv Of 00 Dolol LAII~ 5

~ Iovlato rta Koo So F f Of IICVtfvthf AIICA 1

Dt ~caIr IIDN of trial vrs OvtaaVADIN Valialai ~ I a,

lel+ IIAI Cohtltf 1 Df DVVrco S ~ Oht~ raraALC AIAI SOVLDCNS

~,

FILL Cohlltlt Of AILIT SAND Aho

~ NAVCL, ~IIN VANTINO C Oh II Nf Or C 00 SLt 5 a htl

~ tha tN Al

~Ivlllaa IO 'IILL NISI ~'hl ~ IIADATION aho Dlhll!I, 1 ACtrI Foh TK IVIIoIAIC tv racf TCHICK IrvIVIK.~I INC AIICA Aho TNC FILLLD vALltv AIIOVho SIAIION r ~ IIV. tintrr CONTAIN Cllvtrlco

~ Itwt, AVAOLC, aho SOIL.

C,

~I ar lAL IHl Cohtrt f5 CV'

~'

I ~ VI INCl IIAIVF 5 r IIN

~ *-

~

~

rr

~ FA ULI ULS VL4 SA TYPICAL SECT IOH KXIITI¹O,OVK¹OUIIOCII FIIONI AAVOIII ODUSLC LalCII Or ASOO Lo OOLOS VHI'IS r IST VKDCNLATCHI 1000 10 Aooo t,4 CTOHC UNITS f145 A 4000 LOST SHD UHOCIILATCAI 14 10 SSS LO 5'IOHC UNIIS tTSS A

ISO LDSI Sao UNOCNLATCIII S.S TO It.o LO STONC VNIIS ITSS 4

1. ~ LDSI

~ AC ~

ANUONI CINOLC LafCN OF lo.ooo IO lr,ooo L ~ 5IONC AIIUOA UHIIC I'7$ 5 A

11,000 lot)

FIGURE 1

Revetment - Ditch Typical Cross Section.

~ hl~

'ine Nile Point - Unit 2

0

> yl

~

~

~

~

t

~

~

~

~

~

g g~gp~g

)a Sg~

) 3) 1

~f)g5! )$ggg

) p g

I g

g pgg g

W %8 5 SR~If 5

e ap a

~pp M

L AC'p~Q g R

)LAN/

ga L'gK~) la R~~g

)

k

~g L~sR~<~J f

-Rgt g

ijg-

"~ iR W ll ~ SHIA%%I 0 I%1% 0

~ 15 8

1%

~ SOW'WSI ~ III1

~

~

~

~

~

~

~

~