ML20133E707

Forwards Structural & Geotechnical Engineering Branch Request for Addl Info to Complete Review of 850724 Application to Modify Tech Specs Re Spent Fuel Storage Capacity Expansion

ML20133E707
Person / Time
Site:	Millstone
Issue date:	10/03/1985
From:	Butcher E Office of Nuclear Reactor Regulation
To:	Opeka J NORTHEAST NUCLEAR ENERGY CO.
References
TASK-2.E.4.2, TASK-TM TAC-44864, TAC-59294, NUDOCS 8510090507
Download: ML20133E707 (7)

Text

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October 3,1985 DISTRIBUTION:

Docket No. 50-336 SMRT7TEF Gray File NRC PDR L PDR ORB 43 RDG Mr. John F. Opeka, Senior Vice President OELD Nuclear Engineering and Operations EJordan Northeast Nuclear Energy Company BGrimes P. O. Box 270 JPartlow Hartford, Connecticut 06141-0270 00sborne PMKreutzer

Dear Mr. Opeka:

ACRS 10

SUBJECT:

REQUEST FOR ADDITIONAL INFORMATION ON SPENT FUEL STORAGE CAPACITY EXPANSION FOR MILLSTONE UNIT 2 To complete our review of your request dated July 24, 1985 to modify your Technical Specification concerning the spent fuel storage capacity at Millstone Unit 2, we will need responses to the questions in the enclosure.

We request that you provide this infonnation by October 18, 1985, in order to maintain schedules. An advance copy of the enclosure has previously been provided to your staff.

The information requested in this letter affects fewer than 10 respondents; therefore, OMB clearance is not required under P.L.96-511.

Sincerely,

/s/

Edward J. Butcher, Acting Chief Operating Reactors Branch #3 Division of Licensing

Enclosure:

As stated cc w/ enclosure:

See next page 0 j' L

,Plfreb)tzer ORB #3 DL ORB # :D J6udher 00s e:dd

/85 10/f/85 10/1 /85 "10/7 8510090507 851003 PDR ADOCK 05000336 P

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Mr. John F. Opeka Millstone Nuclear Power Station Northeast Nuclear Energy Company Unit No. 2 cc:

Gerald Garfield, Esq.

Mr. Wayne D. Romberg Day, Berry & Howard Superintendent Counselors at Law Millstone Nuclear Power Station City Place P. O. Box 128 Hartford, Connecticut 06103-3499 Waterford, Connecticut 06385 Regional Administrator, Region I Mr. Edward J. Mroczka U.S. Nuclear Regulatory Commission Vice President, Nuclear Operations Office of Executive Director for Northeast Nuclear Energy Company Operations P. O. Box 270 631 Park Avenue Hartford, Connecticut 06141-0270 King of Prussia, Pennsylvania 19406 Pr. Charles Brinkman, Manager Washington Nuclear Operations C-E Power Systems Combustion Engineering, Inc.

i 7910 Woodmont Avenue I

Bethesda, Maryland 20814 Mr. Lawrence Bettencourt, First Selectman

-Town of Waterford Hall of Records - 200 Boston Post Road Waterford, Connecticut 06385 Northeast Utilities Service Company ATTN: Mr. Richard R. Laudenat, Manager Generation Facilities Licensing Post Office Box 270 Hartford, Connecticut 06141-0270 Kevin McCarthy, Director Radia' tion Control Unit Department of Environmental Protection State Office Building Hartford, Connecticut 06106 Mr. John Shedlosky Resident Inspector / Millstone Box 811 Niantic, Connecticut 06357 Office of Policy & Management ATTN: Under Secretary Energy Division 80 Washington Street i

Hartford, Connecticut 06106 i

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a ENCLOSURE RAI FOR MILLSTONE - 2 SFP STRUCTURAL AND GE0 TECHNICAL ENGINEERING BRANCH

Reference:

Letter from J. F. Opeka of Northeast Utilities to E. J. Butcher of NRC, " Millstone Nuclear Power Station, Unit No. 2. Proposed Change to Technical Specifications, Modifications to Spent Fuel Storage Pool", dated July 24, 1985.

1.

With respect to seismic loadings on the spent fuel rack modules:

a.

Identify which rack modules were analyzed.

b.

Provide a description of how the horizontal earthquake acceleration (time history) was oriented relative to the long and short cross-sectional dimensions of the rack modules in the non-linear displace-ment analysis, Describe what constitutes the worst case (identifying the factors by c.

which the worst case was identified) and how it was considered.

2.

Reference 4-2 was cited on page 22 of the Licensee's report (see above reference) in lieu of any description of the non-linear analysis model:

Provide the relationship of this reference to the analysis performed a.

for the Licensee's report, b.

Describe how the analysis for the Licensee's report differed from that presented in the referenced technical paper, c.

Provide a copy of the reference to expedite the review.

3.

Provide a full description of the mathematical model used for the non-linear rack module analysis.

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2-4.

In addition to not providing the mathematical model for the non-linear dynamic displacement analysis, the Licensee did not indicate the relation-ship of the rack module analyzed to its adjacent rack modules. The fol-

.i lowing information is required:

a.

Describe and justify how in-phase and/or out-of-phase motion with adjacent rack modules was considered and implemented, b.

Describe fully how hydrodynamic coupling to adjacent rack modules was considered and justify the use of the theoretical basis employed.

Describe how the gap between adjacent rack modules was apportioned c.

to each rack module and list the values for the racks analyzed, q

d.

Provide numerical comparisons of rack displacements (at the top of the

(

rack if that is the point of maximum displacement) to the apportioned clearance, Where references are cited, please provide a copy of each reference e.

with the response to expedite the review.

j 5.

With respect to the modeling of impact between the fuel assembly and a rack cell in the non-linear dynamic analysis:

a.

Provide the data and structural premise upon which impact stiffness was based.

b.

Provide the value of impact damping used, if greater than the nominal structural damping used in the analysis, and provide documentation just-ifying that damping value.

j 6.

The Licensee did not indicate what range of friction coefficnet values was used in the non-linear displacement analysis between the rack mounting feet and the pool floor liner:

a.

Provide the range of friction coefficient used and describe the proced-ures used to determine the friction coefficient that produces the maxi-mum rack displacement.

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. b.

Justify and document the validity of the range of friction coefficient used.

7.

The Licensee did not indicate how the results from the non-linear dis-placement analysis was introduced to the stress analysis model, a.

Provide full description of the load selection process and how the vertical and lateral dynamic loads on each rack mounting foot, as well as rack dead weight, are considered during rack lift-off in the stress analysis model.

8.

Non-linear analyses, especially those involving impact of bodies as occurs between the fuel assemblies and the rack module, and between the rack mounting feet and the pool floor during lift-off, generally require add-itional procedures such as repeated solutions using a range of integration time steps to assure that the solution is both stable and fully converged.

This is important because integration procedures that have yielded a valid solution do not necessarily remain stable for all solutions. The Licensee made no mention of this important point.

a.

Provide a description of the methods used to assure that a valid solution of the non-linear analysis was reached for all cases in-vestigated.

9.

At the bottom of page 22 of the Licensee's report, the Licensee stated that "The component stress on each element resulting from the application of each directional load is combined by the square root sum of the squares method".

No computed stresses or allowable stresses were provided:

a ihe Licensee should document how the stresses, thus calculated, repre-sent the worst case.

b.

The Licensee should provide a table of calculated maximum stresses, allowable stresses, and design margins.

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j c.

The Licensee should indicate that the stresses are compared to stress l

allowables in accordance with the NRC's "O T Position for Review and Acceptance of Spent Fuel Storage and Handling Applications" (shown l

by the Licensee as Reference 4-1) instead of "by the rules of the ASME....".

(Note the last paragraph on Page 22 of the Licensee's i

Report).

10. With respect to fuel handling accidents as addressed by the Licensee on page 23 of the report:

a.

Provide analysis and justification as to why a spent fuel assembly falling through a rack cell and impacting the bottom of the cell "will not affect the primary function of the racks....".

j b.

Provide the approach, the assumptions, the data employed, and the j

results of analysis performed to assure that a fuel assembly dropped I

through a rack storage cell will not penetrate the bottom of the rack 1

)

module, or, if it does penetrate the bottom of the rack module, that I

it will not damage the pool liner, c.

For the case of a crane uplift accident, provide the method of analysis employed, and the criteria by which the results were judged to be l

acceptable, including identification and documentation of the allow-able stresses.

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11. With respect to the pool structure, the Licensee provided virtually no information attesting to the adequacy of the Licensee's anal)tical pro-cedures, the analysis results or the selection of allowable stresses.

Instead, the Licensee provided only a brief abstract indicating that analysis involving multiple load cases was performed, that concrete sections were checked against the latest revision of the American Concrete Institute Requirements for Nuclear Safety Related Structures - ACI-349-80, j

and that the analysis demonstrated the adequacy of the spent fuel pool and auxiliary building to accomodate the loads associated with the 4

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t increased pool storage capacity. However, none of these procedures or results were provided.

Accordingly, the Licensee is requested to provide a description of all analytical procedures, including assumptions, limitations, justification and documentation of the methods applicability, source and validity of acceptance criteria, and the comparison of results to allowable values.

As a minimum, the information should include the following:

a.

Provide sketches and drawings of the portions of the pool and auxiliary building structures to be modeled.

i b.

Provide a description of the mathematical model employed, including assumptions and limitations of the model, c.

Describe and list the load cases used as well as the justification for these load cases.

d.

Describe how the dynamic interaction between the pool structure and the rack modules was considered, including the value of any associated l

dynamic amplification factors.

Include all assumptions made regarding i

the summation and phase of all rack loads.

e.

Provide analysis of the adequace of the pool floor and liner under the j

l local maximum rack module dynamic mounting foot loads.

f.

Provide identification of the most critical regions of the pool l

structure. List the stresses (thermal, deadweight, seismic and rack I

dynamic loads) and their comparison to allowable values, where the source and justification of the use of that allowable is also docu-j mented.

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