ML093280914

Request for Additional Information Regarding Spent Fuel Pool Rerack License Amendment

ML093280914
Person / Time
Site:	Beaver Valley
Issue date:	12/04/2009
From:	Nadiyah Morgan Plant Licensing Branch 1
To:	Harden P FirstEnergy Nuclear Operating Co
morgan n
References
TAC ME1079
Download: ML093280914 (7)

Text

UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 December 4, 2009 Mr. Paul A. Harden Site Vice President FirstEnergy Nuclear Operating Company Beaver Valley Power Station Mail Stop A-BV-SEB1 P.O. Box 4, Route 168 Shippingport, PA 15077

SUBJECT:

BEAVER VALLEY POWER STATION, UNIT NO.2 - REQUEST FOR ADDITIONAL INFORMATION RE: SPENT FUEL POOL RERACK LICENSE AMENDMENT (TAC NO. ME1079)

Dear Mr. Harden:

By letter dated April 9, 2009, as supplemented by letter dated June 15, 2009, FirstEnergy Nuclear Operating Company (licensee) submitted a license amendment for Beaver Valley Power Station, Unit NO.2 (BVPS-2). The proposed amendment would modify Technical Specifications (TSs) to support the installation of high density fuel storage racks in the BVPS-2 spent fuel pool.

The Nuclear Regulatory Commission (NRC) staff is reviewing the submittal and has determined that additional information is needed to complete its review. The specific questions are found in the enclosed request for additional information (RAI). The NRC staff is requesting a response to the RAI within 45 days of receipt.

The NRC staff considers that timely responses to requests for additional information help ensure sufficient time is available for staff review and contribute toward the NRC's goal of efficient and effective use of staff resources.

P. Harden -2 If you have any questions regarding this issue, please contact me at (301) 415-1016.

Sincerely, Nadiyah S. Morgan, Project Manager Plant Licensing Branch 1-1 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket No. 50-412

Enclosure:

RAI cc w/encl: Distribution via Listserv

REQUEST FOR ADDITIONAL INFORMATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO THE SPENT FUEL POOL RERACK LICENSE AMENDMENT FIRSTENERGY NUCLEAR OPERATING COMPANY FIRSTENERGY NUCLEAR GENERATION CORP.

OHIO EDISON COMPANY THE TOLEDO EDISON COMPANY BEAVER VALLEY POWER STATION, UNIT NO.2 DOCKET NO. 50-412 By letter dated April 9, 2009 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML091210251), as supplemented by letter dated June 15,2009 (ADAMS Accession No. ML091680614), FirstEnergy Nuclear Operating Company (licensee) submitted a license amendment for Beaver Valley Power Station, Unit NO.2 (BVPS-2). The proposed amendment would modify Technical Specifications (TSs) to support the installation of high density fuel storage racks in the BVPS-2 spent fuel pool (SFP). In order to complete the review, the Nuclear Regulatory Commission (NRC) staff needs the following additional information:

Mechanical and Civil Engineering Branch:

(Document reviewed: [Proprietary] Holtec Report No. HI-20841 01, "Mechanical Drop Accident Analyses Supporting Beaver Valley Unit 2 Re-racking Project")

1. Section 1.2 (Scope)

a. State the basis for assuming a drop height of 24" above the top of the rack for the "shallow drop" event and the "gate drop" event.

b. State the basis for assuming a vertical drop of an empty rack from the top of the spent fuel pool water level.

2. Section 4.3 (Material Properties)

a. Page 13 of 52 shows the true stress-true strain curve for SA240-304L. Provide the basis of this curve, or provide a copy of Reference 3.

b. Provide the true stress-true strain curve for SA564-630.

c. Provide the bilinear engineering stress-strain relationship and its source for the weld material.

Enclosure

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d. Provide the true failure strains and corresponding true stresses for the materials listed on page 12 of 52.

e. Page 13 of 52 lists the strain rate effect considered in the weld material model, which is based on actual test results for A36 steel. Provide the justification for applying these strain rate effects to stainless steel material, or provide the ADAMS Accession No. for the NRC safety evaluation report on Reference 4.

3. Section 7.1 (Analyses)

a. The acceptance criterion for the "shallow drop" accident is that the plastic deformation of the rack cell wall resulting from a fuel assembly drop event must not extend into the "poison zone." For this accident, the fuel assembly is assumed to hit a peripheral cell wall (filler panel). Figure 12, "Rack Plastic Strain," shows that the calculated fuel assembly displacement of 5.32 inches occurred by crushing the cell wall to a depth of 5.32 inches. The extent of plastic deformation measured from the rack top was determined as 17.91 inches. Provide the methodology and criteria used by LS-DYNA to determine these values.

b. Indicate if LS-DYNA was benchmarked for the case of edge crushing of a plate with boundary conditions as shown in Figure 12, or provide justification showing that these values are conservative, Le., indicate if any tests or independent calculations were performed to provide assurance that the crushing depth and the extent of the plastic deformation as calculated by LS-DYNA have not been underestimated.

c. The maximum effective plastic strain is shown as 0.513 in/in at element 2623. On page 12 of 52, the failure strain is listed as 0.4 in/in. Provide justification as to why the effective plastic strain is greater than the listed failure strain. Explain why the figure shows the largest strains in the range of 0.1027 - 0.1541 in/in.

4. Appendix B: Impact Velocity Calculations

a. In equations A-3A on page B-2, state why the effect of the virtual mass is included in the equation for beta, when it is stated that the virtual mass is neglected for conservatism.

b. Provide a sketch of the transfer canal gate, and state why the thickness of 7.375 inches used in the calculation of the gate weight is conservative compared to 7.875 inches.

c. Page B-18 shows the weight of the gate as 4020 pound-force (Ibf). The length dimension is not given. Based on the dimension of the length provided on page 11 of 52, and using 7.375 inches for the thickness, the weight of the gate is calculated as 26,600 Ibf. Provide a justification for the value given on page B-18, 4020 Ibf.

The NRC staff has also reviewed Section 5.0, "Structural/Seismic Considerations" of Enclosure B of Reference 1 and [Proprietary] Holtec International Report No. HI-2084123,

- 3 "Structural/Seismic Analysis for Beaver Valley Unit 2." The NRC staff has identified the following additional information that is needed to complete its review of this report:

5. Provide the basis for the spring constants for the concrete slab and for the cellular structure on page A-6.

6. Reference 5 stated that "In specific design applications, the authors have used four beam elements and five nodal points to represent the rack structure." Provide justification for representing the model of a generic rack module by a single beam and two nodes in the Beaver Valley Unit 2 seismic analysis.

7. Provide the method for calculating the mass matrix for the single beam and two nodes.

8. Provide a description of the method for determining the impact of the fuel masses and the single beam rack module.

(Document reviewed: [Proprietary] Holtec Report No. HI-2084123)

9. Figures Figure 1.1 shows that the corners of some racks do not match, so that impact could occur somewhere between the corners of one of the racks. An example is a corner of Rack A-3 impacting the middle of the top of Rack B-3, and a corner of Rack B-3 impacting Rack A-3 one cell length from the corner. Since impact between racks is assumed to occur at the corners only, provide the method for determining the impact loads for impact that does not occur at the corners.

10. Appendix A Page A-8

a. In the calculation of the compression spring stiffness for rack-to-rack top impacts, provide the basis for assuming a characteristic length of 3-cell inside diameters and 1-cell depth for the vertical distance.

b. Provide the basis for the formula for the damping values.

Page A-11

c. Provide the basis for the formula for the structural damping multiplier.

11. Appendix 0 Page 0-18

a. The highest impact load is determined as occurring between Racks A-2 and A-3.

Provide the basis for assuming that 8 compression members (cell walls) are available to resist the rack-to-rack impact load of 108,430 Ibf, when impact is assumed to occur at the cell corners only.

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b. Provide a sketch showing the configuration chosen for determining the compression stresses. Indicate the location of the "reinforcement bar thickness,"

which is not included in the description of the rack modules.

Page 0-19

c. Provide the basis for assuming "all edges clamped" plates in the buckling analysis, when at least one of the cell edges is free.

Balance-of-Plant Branch

12. In Section 6 of Enclosure B to Reference 1, the criteria for bulk pool temperature is defined to be 170 0 F for case 1 and 173 0 F for case 2. In both cases, the local temperature in the rack cells shall be demonstrated to be below the local saturation temperature. These criteria are applicable to all rack areas in the pool.

As part of the installation of new racks in the BVPS-2 SFP, a new rack will be temporarily placed in the cask pit area. On page 6-13 of Enclosure B to Reference 1, it is stated that, "An additional CFD model of the rack in the cask pit was constructed and analyzed, and demonstrated that the rack in the cask pit condition is bounded by the normal condition with all racks in the SFP." However, no additional detail is provided.

Provide further description of the analysis performed and results obtained from the modeled fuel rack in the cask pit area demonstrating that there is adequate cooling flow to the cask pit area, that pool temperatures within the cask pit will remain within allowable values, and that local temperature in the rack shall be below the local saturation temperature.

References

1. Letter of April 9, 2009, from Peter. P. Sena, III, FENOC, to Document Control Desk, with Enclosure B, "Holtec Licensing Report for Beaver Valley Unit 2 Rerack (Proprietary Version)."

2. Holtec Report HI-2084010, "Mechanical Drop Accident Analyses Supporting Beaver Valley Unit 2 Reracking Project," March 3, 2009.

3. HI Position Paper DS-307, "Construction of True Stress-True Strain Curve for LS-DYNA Simulations," Rev. 2.

4. Holtec Report HI-2033134 (Safeguards),"Updated Structural Evaluation of an F-16 Aircraft Impact on HI-STORM Overpacks at the PFS Facility," Rev. 2.

5. Soler, A. I., and Singh, K. P., "Seismic Response of a Free Standing Fuel Rack Construction to 3-D Floor Motion," Nuclear Engineering and Design, 80 (1984).

P. Harden - 2 If you have any questions regarding this issue, please contact me at (301) 415-1016.

Sincerely, IRA!

Nadiyah S. Morgan, Project Manager Plant Licensing Branch 1-1 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket No. 50-412

Enclosure:

RAI cc w/encl: Distribution via Listserv DISTRIBUTION:

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