ML19291F740
| ML19291F740 | |
| Person / Time | |
|---|---|
| Site: | Quad Cities  |
| Issue date: | 02/08/1982 |
| From: | Knight J Office of Nuclear Reactor Regulation |
| To: | Novak T Office of Nuclear Reactor Regulation |
| Shared Package | |
| ML19291F741 | List: |
| References | |
| NUDOCS 8202240060 | |
| Download: ML19291F740 (1) | |
Text
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DISTRIBUTION FEB 0 8 7982 DCD 016 Docket Hos.: 50-254 SEB RDG, FILE 50-265 7}
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MEMORANDUM FOR: Thomas Novak, Assistant Director
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for Operating Reactors
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James P. Knight, Assistant Director i
for Components and Structures Engineering d " O-. y~~ '" /[
Division of Engineering L.
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SUBJECT:
QUAD-CITIES STATION UNITS 1 AND 2 FUEL STORAGE
'"'/is MODIFICATION TAC. N0 43759 AND 43760 Plant Name: Quad-Cities Station Units 1 and 2 Docket Nos.: 50-254 and 50-265 License Hos.:
DPR-29 and DPR-30 Respons ble Branch and Project Manager: ORBf2, R. Bevan Description of Task: Spent Fuel Storage Modification Review Status: SER Complete The Structural Engineering Branch has reviewed the structural aspects of the information submitted by Commonwealth Edison Company regarding Quad-Cities Station Units 1 and 2 Fuel Storage Modification. We condlude that the proposed spent fuel storage modification is acceptable. Our Safety Evaluation Report is enclosed.
The enclosure was prepared by Owen Rothberg of the Structural Engineering Branch, g,y ~
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,T u.e _ i James P. Knight, Assistant Director for Conponents and Structures Engineering Division of Engineering
Enclosure:
As stated cc:
R. Vollmer F. Schauer
- p. Kuo T. Ippolito R. Beven
- 0. Rothberg CONTACT:
- 0. Rothberg, SEB, x27864
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ENCLOSURE COMMONWEALTH EDISON COMPANY QUAD-CITIES STATION UNITS 1 AND 2 DOCKET NUMBERS 50-254 AND 50-265 LICENSE NUMBERS DPR-29 AND DPR-30 By letter dated flarch 26, 1981, Common.tealth Edison Company requested a change to Operating License Nos. DPR-29 and DPR-30 and Appendix A Technical Specifi-cations.
The proposed modification concerns increasing the storage capacity in the spent fuel pools from 2920 space to 7684 storage spaces.
High density fuel storage racks, containing Boraflex, a neutron absorbing material, will extend fuel storage capability through about the year 2000. At that time the ability to accommodate an emergency full core discharge will be lost.
Quad-Cities Units 1 and 2 each possess fuel storage pools 33' wide x 41' long.
Unit 1 pool will contain 19 high density fuel racks in 7 different module sizes
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with a total of 3714 storage locations, while Unit 2 pool will contain 3970 storage cells arranged in 20 racks with 6 different module sizes in this pool.
All modules are free standing, i.e., they are not anchored to the pool walls.
The minimum gap between adjacent racks is 3.0" at all locations and between the racks and the fuel pool walls is 9".
Due to these gaps, the possibility of inter-rack impact, or rack collision with pool wall hardware during the postulated ground seismic motion is precluded.
The racks will be constructed from ASTM 240 - 304, austenitic steel sheet material, ASTM 204 - 304 austenitic steel plate material, and ASTM 182 - F304 austenitic steel forgoing material. A typical module contains storage cells
Page 2 of Enclosure which have 6" minimum internal cross-sectional opening.
Skip welding at the top ensures proper venting of the sandwiched space in the sub-elements which make up the fuel racks.
The rack assembly is typically supported on four plate type supports. The supports elevate the nodule base plate 6.5" above the pool floor level, thus creating the water plenum for coolant flow.
Further details of the spent fuel pool racks are illustrated in the licensee's submittals.
STRUCTURAL AND MECHANICAL The design of the racks, fabrication, and installation criteria; the structural design and analysis procedures for all loadings, including seismic and impact loadings; the load combinations; the structural acceptance criteria; the quality assurance requirements for design, and applicable industry codes were all reviewed in accordance with the applicable portions of the current "0T Position for Review and Acceptance of Spent Fuel Pool Storage and Handling Applications", dated April.1978, including revisions, dated Januray,1979.
For the design of the spent fuel modules, two sets of criteria were to be satisfied. The first criteria ensures that adjacent racks will not impact during the SSE, assumming the lower bound value of the pool surface friction coefficient.
It is also required in this criteria that the factors of safety against tilting are met (1.5 for OBE and 1.1 for SSE). The second criteria ensures that loading combinations and stress allowables are in accordance with Section III, Subsection NF of the ASME 1980 Edition. The
Page 3 of Enclosure basic material allowables, fabrications, installations and quality control of the modules are, also, conform with the same code. The loading con-sidered in the analysis involves dead loads, live loads, thermal loading, and seismic loadings (0BE or SSE). Additional analyses were performed to evaluate the effect of fuel assembly drop accident on the racks on the fuel pool liner and the fuel handling crane uplif t accident.
A dynamic model consisting of beams, gaps, springs, dampers and inertia coupling representing fluid coupling between rack and assemblies, and between rack and adjacent racks was used to predict the maximum sliding distance and seismic forces during design earthquake. These forces were then used to predict the seismic stresses and displacements.
The coefficient of friction between the stainless steel liner and the racks leveling legs used in the analysis was chosen based on the information provided in a report ty.E. Rabinowicz of Massachusetts Institute of Technology entitled " Friction Coefficients of Water Lubrication Stainless Steel for a Spent Fuel Rack Facility" dated November 5, 1976. The result of this analysis indicates that although the proposed racks which are free-standing may slide towards each other during SSE, sufficient gaps are provided between the models and the models and the pool walls such that the inter-rack iinpact, or the rack collision with other pool walls is precluded.
The postulated assembly drop was considered in the analysis of the racks.
Two postulated drops were analyzed. The first drop is a straight drop
Page 4 of Enclosure of a fuel assembly dropping from a maximum of 36" above the storage location and impac. ting the base.
The second drop involves a fuel assembly dropping from a maximum of 36" above the rack and hits top of the rack.
In both cases, the impact energy is dissipated by local yielding, however, the sub-criticality of the fuel arrays is not violated.
The effect of postulated stuck fuel assembly due to the attempted withdrawl was considered and the damage if any was required to be limited to the region above the active fuel elements.
The fuel pool concrete and liner were evaluated for the additional loads imposed by the new racks. And it was concluded that the structural members of the fuel pools are adequate to withstand the additional loads imposed by the new racks.
EVALUATION AND CONCLUSION The analysis, design, fabrication, and criteria for establishing installation procedures of the proposed new spent fuel racks are in conformance with accepted codes, standards and criteria. The structural design and analysis procedurer f ar all loadings, including seismic, thermal, and impact loading; the acceptance criteria for the appropriate loading conditions and combinations; and the applicable industry codes are in accordance with appropriate sections of the NRC Staff "0T Position for Review and Acceptance of Spent Fuel Storage and Handling Applications".
Page 5 of Enclosure Allowable stress limits for the combined loading conditions are in accordance with the ASME Code, App. XVII. Yield stress values at the appropriate temper-ature were obtained from Section III of the ASME Code. The quality assurance and criteria for the materials, fabrication and installation of the new racks are in accordance with the accepted requirements of the ASME Code.
The effects of the additional loads on the existing pool structure due to the new fuel racks, existing fuel racks, and equipment have been examined.
The pool structural integrity is assured by conformance with the Standard Review Plan Section 3.8.4.
Results of the seismic and structural analyses indicate that the racks are capable of withstanding the loads associated with all design loading conditions. Also, impact due to fuel assembly / cell interaction has been considered, and will result in no damage to the racks or fuel assemblies.
Results of the dropped fuel assembly analyses show that local rack deformation will occur, but indicate that computed stresses meet the applicable allowables and that the integrity of the racks is maintained.
Results of the dropped heavy loads over the protective ' pool cover indicate that although local damage and plastic deformation may occur, the overall structural integrity of the cover is maintained and is within the acceptable limits.
Page 6 of Enclosure Results of the stuck fuel assembly analysis show that the stress is below those allowed for the applicable loading combinations.
We find that the subject modification proposed by the licensee is acceptable and satisfies the applicable requirements of the General Design Criteria 2, 4, 61, and 62 of 10 CFR, Part 50, Appendix A.
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