ML20134Q133

Requests Addl Info Re Amend to Licensing Basis for Prairie Island Cooling Water Sys Emergency Intake for Plant,Units 1 & 2

ML20134Q133
Person / Time
Site:	Prairie Island
Issue date:	02/21/1997
From:	Wetzel B NRC (Affiliation Not Assigned)
To:	Richard Anderson NORTHERN STATES POWER CO.
References
TAC-M97816, TAC-M97817, NUDOCS 9702260276
Download: ML20134Q133 (6)

Text

. _ ._m . .. _ _ _ . . ... _ _ _-.- .- ___ . . _ _ _ __ _ _ __

Mr. Roger 0. Anderson, Director February 21, 1997 Licensing and Management Issues Northern States Power Company 414 Nicollet Mall 1 -Minneapolis, Minnesota 55401

SUBJECT:

REQUEST FOR ADDITIONAL INFORMATION ON THE PRAIRIE ISLAND NUCLEAR .

GENERATING PLANT, UNITS 1 AND 2, AMENDMENT OF COOLING WATER SYSTEM l EMERGENCY INTAKE DESIGN BASIS (TAC NOS. M97816 AND M97817) l

Dear Mr. Anderson:

By letter dated January 29, 1997, as supplemented February 11 and 12, 1997, i Northern States Power Company (NSP) submitted a request to amend the licensing basis for the Prairie Island cooling water system emergency intake. In order l to review the proposed changes the staff requires some additional information.

Our request for additional information (RAI) is enclosed.

In order to continue our review of your submittal on an exigent basis, please provide your response to the staff's RAI as soon as practical. If you have I any questions regarding the content of the RAI, please contact me at (301) 415-1355.

1 Sincerely, I Original Signed by: l I

Beth A. Wetzel, Project Manager Project Directorate III-I Division of Reactor Projects - III/IV Office of Nuclear Reactor Regulation Docket Nos. 50-282, 50-306

Enclosure:

As stated g gy cc w/ encl: See next page DISTRIBUTION:

ket: File. PUBLIC J. M. Jacobson, DRP, RIII

. 321"Rdg. J. Roe J. Luehman

.E. Adensam (EGA1) OGC ACRS G. Bagchi W. LeFave /

260114

/

DOCUMENT NAME: G:',WPDOCS\ PRAIRIE \PI97332.RAI To receive a copy of thi: document, indicate in the box C= Copy w/o attachment / enclosure E= Copy with attachment / enclosure N =

N do_ copy 0FFICE PM:PD31 ,E s LA:PD31 E D:PD31 m

! m BWetzel M CJamersond[JHannonkkg DATE 2/d//97 2/M /97 2/21/9[

0FFICIAL RECORD COPY 9702260276 970221 DR ADOCK0500g2

.. - - . . . _ . . . . .. - .- . .. -=_- . -. . - . ~ .

pnMoo y" t UNITED STATES s* j 2

NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20066-0001

% ,,,, # February 21, 1997 I

Mr. Roger O. Anderson, Director Licensing and Management Issues Northern States Power Company 414 Nicollet Mall Minneapolis, Minnesota 55401

SUBJECT:

REQUEST FOR ADDITIONAL INFORMATION ON THE PRAIRIE ISLAND NUCLEAR GENERATING PLANT, UNITS 1 AND 2, AMENDMENT OF COOLING WATER SYSTEM EMERGENCY INTAKE DESIGN BASIS (TAC NOS. M97816 AND M97817)

Dear Mr. Anderson:

1 l By letter dated January 29, 1997, as supplemented February 11 and 12, 1997, i Northern States Power Company (NSP) submitted a request to amend the licensing basis for the Prairie Island cooling water system emergency intake. In order to review the proposed changes the staff requires some additional information. I Our request for additional information (RAI) is enclosed.

In order to continue our review of your submittal on an exigent basis, please l provide your response to the staff's RAI as soon as practical. If you have  ;

any questions regt.rding the content of the RAI, please contact me at l (301) 415-1355. i Sincerely, j L , [

Beth A. Wetzel, Pr ect Manager Project Directorate III-I Division of Reactor Projects - III/IV Office of Nuclear Reactor Regulation Docket Nos. 50-282, 50-306

Enclosure:

As stated cc w/ enc 1: See next page I

I t

l 5

s

I Mr. Roger 0. Anderson, Director Prairie Island Nuclear Generating Northern States Power Company Plant I

cc:

J. E. Silberg, Esquire Tribal Council Shaw, Pittman, Potts and Trowbridge Prairie Island Indian Community 2300 N Street, N. W. ATTN: Environmental Department Washington DC 20037 5636 Sturgeon Lake Road Welch, Minnesota 55089 Plant Manager Prairie Island Nuclear Generating Plant Northern States Power Company 1717 Wakonade Drive East l Welch, Minnesota 55089 1 Adonis A. Neblett Assistant Attorney General  !

Office _ of the Attorney General 455 Minnesota Street Suite 900 St. Paul, Minnesota 55101-2127  !

U.S. Nuclear Regulatory Commission Resident Inspector's Office 1719 Wakenade Drive East 1 Welch, Minnesota 55089-9642 I Regional Administrator, Region III U.S. Nuclear Regulatory Commission 1 I

801 Warrenville Road Lisle, Illinois 60532-4351 l l

Mr. Jeff Cole, Auditor / Treasurer Goodhue County Courthouse i Box 408 l Red Wing, Minnesota 55066-0408 i Kris Sanda, Commissioner Department of Public Service 121 Seventh Place East Suite 200 -

St. Paul, Minnesota 55101-2145

~~

Site Licensing Prairie Island Nuclear Generating Plant Northern States Power Company 1717 Wakonade Drive East Welch, Minnesota 55089 hember 1996

?

REQUEST FOR ADDITIONAL INFORMATION FOR REVIEW OF THE AMENDMENT OF THE COOLING

} WATER SYSTEM EMERGENCY INTAKE STRUCTURE DESIGN BASES

! 1. It appears that the N values shown in Reference 1 are the values

calculatedfromtheresultsgtheConePenetrationTests(CPT)using i the equation, N = 0.833

• q + 3.75

• f Provide the results of any 4

existing liquefaction studi,es or empiricaf.tests that verify the i validity of such an equation with comparison of the Standard Penetration

! Tests (SPT) test results; specifically, the soil types at the site l should be considered.

- 2. With respect to the calculated N values, you modified the SPT N, values using the equation, N, = N

• Cn .

I a) The values of Cn , the correction factor, shown in Figure 3 of

] Reference 1 are based on the SPT test results. Explain the i applicability of the values for the CPT test results.

! b) These values of C are based on the material being fine sands.

l Discuss the applicability of these values for the soils present at

your site.

c) There are two curves in Figure 3 of Reference 1 for determining the values of C : one curve is for the relative density of fine sand, D

= 40 to 60 S and the other curve for D = 60 to 80 %. Youhaveuseil theaverageofthesetwocurvesforfiEidingC while the small N values (i.e.,N=7to11)havetherelativeS,ensityofD less than 40 %. Justify why you did not use the curve for D = 40 fo 60 %

rather than using the average curve to obtain a mo,re accurate liquefaction analysis, d)

Justify relative the useofof D[),=

density less40 to4060%.% curve for fine sand that has a than e) You have concluded that there is no liquefaction potential based on the Cyclic Strength Ratio (CSR) which is related to the N value, thereby to the Cn .

However, if one uses a C value from n

less the D,(=

to 6040 than  %%),

curve oraeven then a smaller smaller C value CSR should because be found. of smaller Therefore, i D't may be concluded that there is a liquefaction problem in the Intake Canal soil layers. Justify your conclusion of the liquefaction analysis with respect to the accuracy of your Cn values, f) All eight (8) CPT tests were performed at the heel side of the Intake Canal embankment. Considering your use of the Seismic Stress Ratio (SSR) which is a function of a stress reduction coefficient and a ratio of the total and effective overburden pressures, you ENCLOSURE

~ - _ - - . . . ~ - . - - . - . . - _ . _ - - - _ - . - . - - - - -

i j i i should have performed CPT and/or SPT tests near to the toe of the

! embankment and/or away from the toe on the floor of the canal to 1 identify a liquefiable soil. They are the locations which provide a j higher SSR and thus a smaller factor of the safety against a liquefaction. Discuss the adequacy of your test locations. Discuss

! also whether you can extend the soil condition from the heel side to

the toe side and to the location of the intake pipe for a j

liquefaction analysis.

l g) The CPT tests were performed to the depths approximately 43 to 46

} feet below the grade. Explain why the tests were not extended to a deeper layer and how you are certain that there are no liquefiable

! soil layers beyond 46 feet.

i

h) Three (3) SPT tests were performed, and two SPT tests were done near i the two CPT test locations. The NRC staff compared the SPT and CPT i test results, and found that the SPT test results show smaller N j values (i.e., 4 to 7). Using the actual SPT N values, which is a more common approach in practice, demonstrate there is no liquefaction problem in the intake canal.

i) Your previous contractors, Blume & Associates, Dames & Moore, and i Bolton Seed, concluded that there are liquefiable soils around the i intake canal area. However, your new contractor, STS Consultants

! Ltd., concluded that there are no liquefiable soils. Explain such

inconsistent conclusions based on: (1) the SPT and CPT testing

! methods, (2) reliability of the testing results from both tests, (3) contractors' engineering judgment and interpretation of the testing results, and (4) the cor. tractors' view and understanding on j

the importance of the seismically qualified Category 1 structure.

3. Using the Bishop's and Spencer's methods, you performed the slope i stability analyses for the Intake Canal embankment. In the analyses, a

full soil shear strength was assumed along a circular failure surface, 4

since you assumed that there is no liquefaction in the soil layer.

, However, the slope stability is coupled with the earthquake loading.

i Therefore, it is more appropriate to use other methods (e.g., a dynamic

! finite element analysis with an appropriate time history input, a Wedge

} analysis with a possible failure line where the shear strength is low

~

(small N values), etc.) for a slope stability analysis. Justify the adequacy of your slope stability analysis methods in view of shear strength development along the failure circle and a postulated failure circle.

4. We understand that you are reanalyzing the slope stability with considerations of the horizontal (0.12 g) and vertical (0.08 g) inertial forces. We expect you to use two possible soil slope failures: (1) one failure circle at the lowest factor of safety from a family of the shallow slope failure circles and (2) the other failure circle at the lowest factor of safety from a family of the base slope failure circles.

Provide the reanalysis report with complete calculations. If the reanalyses are done using computer programs, submit the programs, inputs

n i

f .

l and outputs for a review. However, if the computer programs are

- proprietary information, you are requested to submit the hand

calculations for only the final two cases.

5. With regards to the capacity of the emergency intake line, in your January 29, 1997, submittal, you proposed changes to USAR [ updated

safety analysis report], Section 10, to state that "preoperational testing, when extrapolated for minimum submergence, demonstrated that

. only 15,000 gpa is actually available." Your submittal does not j indicate what the flow demand of the cooling water system will be after

operator actions are completed to reduce that demand to within the

{ capacity of the intake line. What is the flow demand of the cooling water system after the operator actions, and what actions are planned to

. ensure that the flow capacity of the intake line (at the minimum

. submergence level) will continue to meet or exceed the cooling water system flow demand for the life of the plant? Will the minimum required capacity of the intake line be 15,000 gpn or some other justifiable flow l rate?

l '

i 4

5

$ l 5 I l

.