Referencing 4/14/78 Letter-Modifications to NRC Guidance "Review and Acceptance of Spent Fuel Pool Storage and Handling Applications" (Generic Letter 79-04)


                              UNITED STATES 
                          WASHINGTON, D. C. 20565 

                             January 18, 1979 

To All Power Reactor Licensees 


Our letter of April 14, 1978, provided NRC Guidance entitled, "Review and 
Acceptance of Spent Fuel Storage and Handling Applications." Enclosed are 
modifications to this document for your information and use. These involve 
pages IV-5 and IV-6 of the document and comprise modified rationale and 


                                   Brian K. Grimes, Assistant Director 
                                        for Engineering and Projects 
                                       Division of Operating Reactors 

Pages IV-5 and IV-6 

cc w/enclosure: 
Service List  


     In order to determine the flexibility of the pool wall it is acceptable
     for the licensee to use equivalent mass and stiffness properties 
     obtained from calculations similar to those described in "Introduction 
     to Structural Dynamics" by J. M. Biggs published by McGraw Hill Book 
     Company. Should the fundamental frequency of the pool wall model be 
     higher than or equal to 33 Hertz, it may be assumed that the response 
     of the pool wall and the corresponding lateral support to the new rack 
     system are identical to those of the base slab, for which appropriate 
     floor response spectra or ground response spectra may already exist. 

(6)  Structural Acceptance Criteria 

     When AISC Code procedures are adopted, the structural acceptance 
     criteria are those given in Section 3.8.4.II.5 of the Standard Review 
     Plan for steel and concrete structures. For stainless steel the 
     acceptance criteria expressed as a percentage of yield stress should 
     satisfy Section 3.8.4.II.5 of the Standard Review Plan. When subsection
     NF, Section III, of the ASME B&PV Code is used for the racks, the 
     structural acceptance criteria are those given in the Table below. When
     buckling loads are considered in the design, the structural acceptance 
     criteria shall be limited by the requirements of Appendix XVII-2110(b) 
     of the ASME Boiler and Pressure Vessel Code. 

     For impact loading the ductility ratios utilized to absorb kinetic 
     energy in the tensile, flexural, compressive, and shearing modes should
     be quantified. When considering the effects of seismic loads, factors 
     of safety against gross sliding and overturning of racks and rack 
     modules under all probable service conditions shall be in accordance 
     with the Section 3.8.5.II-5 of the Standard Review Plan. This position 
     on factors of safety against sliding and tilting need not be met 
     provided any one of the following conditions is met: 

     (a)  it can be shown by detailed nonlinear dynamic analyses that the 
          amplitudes of sliding motion are minimal, and impact between 
          adjacent rack modules or between a rack module and the pool walls 
          is prevented provided that the factors of safety against tilting 
          are within the values permitted by Section 3.8.5.II.5 of the 
          Standard Review Plan. 

     (b)  it can be shown that any sliding and tilting motion will be 
          contained within suitable geometric constraints such as thermal 
          clearances, and that any impact due to the clearances is 

(7)  Materials, Quality Control, and Special Construction Techniques: 

     The materials, quality control procedures, and any special con-
     struction techniques should be described. The sequence of installation 
     of the new fuel racks, and a description of the precautions to be taken
     to prevent damage to the stored fuel during 



Load Combination 
Elastic Analysis                                          Acceptance Limit 

D + L                                   Normal limits of NF 3231.1a 

D + L + E                               Normal limits of NF 3231.1a 

D + L + To                              Lesser of 2Sy or Su stress range 

D + L + To + E                          Lesser of 2Sy or Su stress range 

D + L + Ta + E                          Lesser of 2Sy or Su stress range 

D + L + Ta + E1                         Faulted condition limits of  
                                             NF 3231.1c 

Limit Analysis 

1.7 (D + L)                             Limits of XVII-4000 of Appendix XVII
                                        of ASME Code Section III 

1.7 (D + L + E) 

1.3 (D + L + To) 

1.3 (D + L + E + To) 

1.1 (D + L + Ta + E) 

Notes:    1.   The abbreviations in the table above are those used in 
               Section 3.8.4 of the Standard Review Plan where each term is 
               defined except for Ta which is defined as the highest 
               temperature associated with the postulated abnormal design 
          2.   Deformation limits specified by the Design Specification 
               limits shall be satisfied, and such deformation limits should
               preclude damage to the fuel assemblies. 

          3.   The provisions of NF 3231.1 shall be amended by the 
               requirements of the paragraphs c.2, 3, and 4 of the 
               Regulatory Guide 1.124 entitled "Design Limits and Load 
               Combinations for Class 1 Linear-Type Component Supports."  



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