ML20196A075

Forwards Request for Addl Info Re Spent Fuel Racks.Response Requested within 30 Days of Ltr Receipt

ML20196A075
Person / Time
Site:	Vogtle
Issue date:	06/15/1988
From:	Hopkins J Office of Nuclear Reactor Regulation
To:	Hairston W GEORGIA POWER CO.
References
TAC-67079, NUDOCS 8806290441
Download: ML20196A075 (6)

Text

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June 15, 1988 Docket No. 50-425 Mr. W. G. Hairston, III Senior Vice President -

Nuclear Operations Georgia Power Company l P.O. Box 4545 Atlanta, Georgia 30302 l

SUBJECT:

V0GTLE UNIT 2 REQUEST FOR ADDITIONAL INFORMATION SPENT FUEL RACKS (TAC 67079) i The NRC staff is reviewing the Vogtle Unit 2 spent fuel racks described in the letter submitted December 23, 1987. The NRC staff finds that it needs additional infonnation (see enclosure) in order to complete its review. In order to maintain our review schedule, we reauest responses within 30 days of receipt of this letter.

The reporting and/or recordkeeping requirements contained in this letter affect fewer than 10 respondents; therefore, OMB clearance is not required under P.L.96-511.

Sincerely,

/s Jon B. Hopkins, Project Manager kbP 00$k O!oook25 Project Directorate 11-3 A PDR Division of Reactor Projects - I/II

Enclosure:

As stated cc:

See next page

, DISTRIBUTION

' Docket File > NRC PDR Local PDR PDII-3 Reading File V0GTLE PLANT FILE EJordan MNBB-3302 GBagchi 8D-22 OGC-WF 15B-18 HAshar 8D-22 SVarga 14E-4 Glainas 14H-3 BGrimes 9A-2 MRood DMatthews JHoph;ns ACRS (10) H-1016 LA 2 PM:PDII-3 D: -

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June 15, 1988 Docket No. 50-425 Mr. W. G. Hairston, III Senior Vice President -

Nuclear Operations Georgia Power Company P.O. Box 4545 Atlanta, Georgia 30302

SUBJECT:

V0GTLE UNIT 2 REQUEST FOR ADDITIONAL INFORMATION SPENT FUEL RACKS (TAC 67079)

The NRC staff is reviewing the Vogtle Unit 2 spent fuel racks described in the letter submitted December 23, 1987. The NRC staff finds that it needs additional information (see enclosure) in order to complete its review. In order to maintain our review schedule, we reouest responses within 30 days of receipt of this letter.

The reporting and/or recordkeeping requirements contained in this letter affect fewer than 10 respendents; therefore, OMB clearance is not required under P.L.96-511.

Sincerely, s/

Jon B. Hopkins, Project Manager Project nirectorate II-3 Division Jr Reactor Projects - I/II

Enclosure:

As stated cc:

See next page DISTRIBUTION Docket File NRC PDR Local PDR PDII-3 Reading File V0GTLE PLANT FILE EJordan MNBB-3302 GBagchi 80-22 OGC-WF 158-18 HAsher 8D-22 SVarga 14E-4 Glainas 14H-3 BGrimes 9A-2 MRood 0Matthews JHopkins L ACRS(10) H-1016 PM:PDII-3 D: h MRd:deLARDy-3JHopkins:pw DMa thews 6 // I/88 4/jf/88 (/g/88

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Mr. W. G. Hairston, III Georgia Power Company Vogtle Electric Generating Plant cc:

Mr. L. T. Gucwa Resident Inspector Manager of Safety and Licensing Nuclear Regulatory Comission Georgia Power Company P.O. Box 572 P.O. Box 4545 llaynesboro, Georgia 30830 Atlanta, Georgia 30302 Deppish Kirkland, III, Counsel Mr. Ruble A. Thomas Office of the Consumers' Utility Executive Consultant Council Southern Company Services, Inc. Suite 225 P.O. Box 2625 32 Peachtree Street, N.E.

Birmingharn, Alabama 35202 Atlanta, Georgia 30302 Mr. Paul D. Rice James E. Joiner Vice President & Project Director Troutman, Sanders, Lockerman, Georgio Power Company & Ashmore Post Office Bcx 282 1400 Candler Building Waynesboro, Georgia 30830 127 Peachtree Street, N.E.

Atlanta, Georgia 30303 Mr. J. A. Bailey Project Licensing Manager Danny Feig Southern Company Services, Inc. 1130 Alta Avenue P.O. Box 2625 Atlanta, Georgia 30307 Birmingham, Alabama 35202 Carol Stangler

< Ernest L. Blake, Jr. Georgians Against Nuclear Energy Bruce W. Churchill, Esq. 425 Euclid Terrace Shaw, Pittman, Potts and Trowbridge Atlanta, Georgia 30307 2300 N Street, N. W.

Washington, D. C. 20037 Mr. R. P. Mcdonald Executive Vice President -

Mr. G. Bockhold, Jr. Nuclear Operations General Manager Nuclear Operations Georgia Power Company Georgia Power Company P.O. Box 4545 P.O. Box 1600 Atlarita, Georgia 30302 Waynesboro, Georgia 30830 Regional Administrator, Region II U.S. Nuclear Regulatory Comission 101 Marietta Street, N.W., Suite 2900 Atlanta, Georgia 30323

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ENCLOSbRE I. SPENT FUEL POOL ANALYSIS

1. Provide sketches and/or drawings of the pool shewing elevations, basemat and pool wall thicknesses, water levels, ano safety related components (such as piping) in the pool, and their clearances f rom the racks.

2. Provide information on how the additional weight of high density racks (HORS) and impacts on floor and walls under the postulated seismic events are incorporated in the design of the pool structure. Provide information re9ted to pool structure seismic responses oue to the proposed reracking, controlling load combinations and stresses at critical structural sections.

3. Provide information on the effects of HOR weight on the soil bearing capacity and liquefaction potential.

II. INPUT SEISMIC MOTION

1. The results of the 3D analysis of HORS cre quite sensitive to the frequency content ano duration of the time histories being used for the analysis. Provide information on how the power spectral d2nsities (P50s) of the proposed synthetic time histories possess reasonably distributed energy content over a frequency range of interest and generally match the target PSD criteria, in additicn to the enveloping criteria of the standard Review Plan 3.7.1. Guidelines for developing PSD can be found in NUREG/CR-3519. "Power Spectral Density Functions compatible with NRC Regulatory Guide 1.60."

III. ANALYSIS AND DESIGN OF HDRs

1. With regard to the modelling and model parameters, provide the following information

a. Flexural rigidities of the fuel assemblies and Justification for modelling them as five separated rattling masses.

b. How is the vertical mass of the fuel assemblies accounted for in the model?

c. Calculations supporting the assumption that fuel racks are rigid.

d. Provide additional inf ormation on how the rotetions of the support legs are simulated. How is the limiting condition of slab mcment (P.14, Seismic Analysis) calculated?

e. Provide information en how the non-symmetrical arrangement of the fuel-cell lateral supports (Fig. 9.1.2 - 28) is accounted for in the rack analysis.

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f. Because of the unpredictable nature of the rack movements under seismic event, it is not conceivable to assign one value (so called "conservative") to model parameters such as spring constants. Provide the numerical values associated with Table 2 of the Seismic Analysis and an estimate of potential variation from the best estimate values.

2. The staff had previously reviewed and accepted the results of rack analysis using DYNARACK computer code. However, it appears that the code format has been changed to include the use of non-linear vibration theory and cross coupling effects as indicated in items "n" and "o" of Section 3.1. In light of the changes provide the following information:

a. Demonstrate the validity of the non-linear vibration theory used to simulate gap variation in the fuel-cell impact analysis and in the rack analysis. As the analysis results will lead to less conservative design, provide inclusion of all the associated factors such as realistic modelling of fuel rods comprising a fuel assembly, fluid flow through rods, differences in various fluid paths along the length of the fuel assemblies. Provide verificaticn of the theory with the statistically evaluated experimental results and the limits of their applicability,

b. With regard to the cross-coupling effects due to the movement of fluid arcund the adjacent racks, the staff had accepted its use for two dimensional multi-rack analyses. However, in absence of any experimental verification, the gap distance was conservatively recommended as three tic.es the nominal space between the adjacent racks. Prcvide information on hcw the formulation will be useo to analyze the rack to rack impact at Vogtle 2.

c. Provide a comparative tabulation showing displacements and impact loads using the linear vibration formulation and those using the proposed non-linear vibration theory.

IV. DROPPE0 FUEL ASSEMBLY IMPACT

1. Provide calculations demonstrating the assertion in the submittal that the high shear stresses due to the postulated impact 10a0 will be above the active fuel region.

2. Provide calculations showing the effects of the postulated impact load on the rack baseplate will not damage the pool liner.

V. MISCELLANE0US ITEMS

1. With regard to the planned partial loacing of the pool, provide the folicwing information:

a. Calculation demonstratir.g the stability of the end racks (factors of safety against tilting and overturning) where the fluid coupling effects are negligible.

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b. Calculations in "a" with partial and eccentric loading of the racks.

2. Provide details of the proposed installation procedure indicating how the elevations of the racks and designated gaps between the racks will be maintained and monitored.

3. Provide a description of plant safety procedures in case of:

a. fuel drop occident

b. a seismic event

c. loss of water from the pool detected by leak chases.

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