United States Nuclear Regulatory Commission - Protecting People and the Environment

Bulletin 79-14: Seismic Analyses For As-Built Safety-Related Piping Systems

                               UNITED STATES 
                       NUCLEAR REGULATORY COMMISSION 
                           WASHINGTON, D.C. 20555 

                               July 2, 1979  

                                             IE Bulletin No. 79-14 

SEISMIC ANALYSES FOR AS-BUILT SAFETY-RELATED PIPING SYSTEMS  

Description of Circumstances: 

Recently two issues were identified which can cause seismic analysis of 
safety-related piping systems to yield nonconservative results. One issue 
involved algebraic summation of loads in some seismic analyses. This was 
addressed in show cause orders for Beaver Valley, Fitzpatrick, Maine Yankee 
and Surry. It was also addressed in IE Bulletin 79-07 which was sent to all 
power reactor licensees.  

The other issue involves the accuracy of the information input for seismic 
analyses. In this regard, several potentially unconservative factors were 
discovered and subsequently addressed in IE Bulletin 79-02 (pipe supports) 
and 79-04 (valve weights). During resolution of these concerns, inspection 
by IE and by licensees of the as-built configuration of several piping 
systems revealed a number of nonconformances to design documents which could
potentially affect the validity of seismic analyses. Nonconformances are 
identified in Appendix A to this bulletin. Because apparently significant 
non- conformances to design documents have occurred in a number of plants, 
this issue is generic. 

The staff has determined, where design specifications and drawings are used 
to obtain input information for seismic analysis of safety-related piping 
systems, that it is essential for these documents to reflect as-built 
configurations. Where subsequent use, damage or modifications affect the 
condition or configuration of safety-related piping systems as described in 
documents from which seismic analysis input information was obtained, the 
licensee must consider the need to re-evaluate the seismic analyses to 
consider the as-built configuration. 
.

IE Bulletin No. 79-14                                  July 18, 1979 
Revision 1                                             Page 2 of 3   

Action to be taken by Licensees and Permit Holders: 

All power reactor facility licensees and construction permit holders are 
requested to verify, unless verified to an equivalent degree within the last
12 months, that the seismic analysis applies to the actual configuration of 
safety-related piping systems. The safety related piping includes Seismic 
Category I systems as defined by Regulatory Guide 1.29, "Seismic Design 
Classification" Revision 1, dated August 1, 1973 or as defined in the 
applicable FSAR.  The action items that follow apply to all safety related 
piping 2 1/2-inches in diameter and greater and to seismic Category I 
piping, regardless of size which was dynamically analyzed by computer. For 
older plants, where Seismic Category I requirements did not exist at the 
time of licensing, it must be shown that the actual configuration of 
safety-related systems, utilizing 2 1/2 inches in diameter and greater, 
meets design requirements. 

Specifically, each licensee is requested to: 

1.   Identify inspection elements to be used in verifying that the seismic 
     analysis input information conforms to the actual configuration of 
     safety-related systems. For each safety-related system, submit a list 
     of design documents, including title, identification number, revision, 
     and date, which were sources of input information for the seismic 
     analyses. Also submit a description of the seismic analysis input 
     information which is contained in each document. Identify systems or 
     portions of systems which are planned to be inspected during each 
     sequential inspection identified in Items 2 and 3.  Submit all of this 
     information within 30 days of the date of this bulletin. 

2.   For portions of systems which are normally accessible*, inspect one 
     system in each set of redundant systems and all nonredundant systems 
     for conformance to the seismic analysis input information set forth in 
     design documents. Include in the inspection: pipe run geometry; support
     and restraint design, locations, function and clearance (including 
     floor and wall penetration). embedments (excluding those covered in IE 
     Bulletin 79-02); pipe attachments; and valve and valve operator 
     locations and weights (excluding those covered in IE Bulletin 79-04). 
     Within 60 days of the date of this bulletin, submit a description of 
     the results of this inspection.  Where nonconformances are found which 
     affect operability of any system, the licensee will expedite completion 
     of the inspection described in Item 3. 

*    Normally accessible refers to those areas of the plant which can be 
     entered during reactor operation. 
.

IE Bulletin No. 79-14                                  July 2, 1979 
                                                       Page 3 of 3 

3.   In accordance with Item 2, inspect all other normally accessible 
     safety-related systems and all normally inaccessible safety-related 
     systems. Within 120 days of the date of this bulletin, submit a 
     description of the results of this inspection. 

4.   If nonconformances are identified: 

     A.   Evaluate the effect of the nonconformance upon system operability 
          under specified earthquake loadings and comply with applicable 
          action statements in your technical specifications including 
          prompt reporting. 

     B.   Submit an evaluation of identified nonconformances on the validity
          of piping and support analyses as described in the Final Safety 
          Analysis Report (FSAR) or other NRC approved documents. Where you 
          determine that reanalysis is necessary, submit your schedule for: 
          (i) completing the reanalysis, (ii) comparisons of the results to 
          FSAR or other NRC approved acceptance criteria and (iii) 
          submitting descriptions of the results of reanalysis. 

     C.   In lieu of B, submit a schedule for correcting nonconforming 
          systems so that they conform to the design documents. Also submit 
          a description of the work required to establish conformance. 

     D.   Revise documents to reflect the as-built conditions in plant, and 
          describe measures which are in effect which provide assurance that
          future modifications of piping systems, including their supports, 
          will be reflected in a timely manner in design documents and the 
          seismic analysis. 

Facilities holding a construction permit shall inspect safety-related 
systems in accordance with Items 2 and 3 and report the results within 120 
days. 

Reports shall be submitted to the Regional Director with copies to the 
Director of the Office of Inspection and Enforcement and the Director of the
Division of Operating Reactors, Office of Nuclear Reactor Regulation, 
Washington, D.C. 20555. 

Approved by GAO (R0072); clearance expires 7/31/80. Approval was given under
a blanket clearance specifically for generic problems. 
.                               APPENDIX A 

  PLANTS WITH SIGNIFICANT DIFFERENCES BETWEEN ORIGINAL DESIGN AND AS-BUILT 
                        CONDITION OF PIPING SYSTEMS 

Plant               Difference                    Remarks 

Surry 1             Mislocated supports.          As built condition 
                    Wrong Support Type.           caused majority of pipe
                    Different Pipe Run            overstress problems, not
                    Geometry.                     algebraic summation.

Beaver Valley       Not specifically identified.  As built condition 
                    Licensee reported "as-built   resulted in both pipe and 
                    conditions differ signifi-    support overstress.
                    cantly from original design." 

Fitzpatrick         IE inspection identified      Licensee is using as
                    differences similar to        built configuration 
                    Surry.                        for reanalysis.

Pilgrim             Snubber sizing wrong.         Plant shutdown to restore
                    Snubber pipe attachment       original design condition.
                    welds and snubber support 
                    assembly nonconformances.

Brunswick 1 and 2   Pipe supports undersize.      Both units shutdown to 
                                                  restore original design  
                                                  condition. 

Ginna               Pipe supports not built       Supports were repaired
                    to original design.           during refueling outage.

St. Lucie           Missing seismic supports.     Install corrected 
                    Supports on wrong piping.     supports before start  
                                                  up from refueling.
.

Page 2                       APPENDIX A 

Plant               Difference                    Remarks 

Nine Mile Point     Missing seismic supports.     Installed supports before
                                                  startup from refueling.

Indian Point 3      Support location and          Licensee performing as
                    support construction          built verification to be
                    deviations.                   completed by July 1.

Davis-Besse         Gussets missing from main     Supports would be over-
                    Steam Line Supports.          stressed. Repairs will be 
                                                  completed prior to start- 
                                                  up.
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