Bulletin 79-14: Seismic Analysis 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
safetyrelated 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 nonconformances 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.
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IE Bulletin No. 79-14
July 2, 1979
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. 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 these safety-related systems 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.
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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)j clearance expires 7/31/80. Approval was given
under a blanket clearance specifically for generic problems.
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APPENDIX A
PLANTS WITH SIGNIFICANT DIFFERENCES BETWEEN ORIGINAL DESIGN AND AS-BULT
CONDITION OF PIPING SYSTEMS
PLANT DIFFERENCE REMARKS
Surry 1 Mislocated supports. As built condition
Wrong Support Type. caused by majority of
Different Pipe Run pipe overstress problems,
Geometry. not 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 & 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.
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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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