Bulletin 79-14: Supplement 2, Seismic Analyses For As-Built Safety-Related Piping Systems
SSINS: 6820
Accession No: 7908220109
UNITED STATES
NUCLEAR REGULATORY COMMISSION
OFFICE OF INSPECTION AND ENFORCEMENT
WASHINGTON, D.C. 20555
September 7, 1979
IE Bulletin No. 79-14
Supplement 2
SEISMIC ANALYSIS FOR AS-BUILT SAFETY-RELATED PIPING SYSTEMS
Description of Circumstances:
IE Bulletin No. 79-14 was issued on July 2, revised on July 18, and first
supplemented on August 15, 1979. The bulletin requested licensees to take
certain actions to verify that seismic analyses are applicable to as-built
plants. Supplement 2 provides the following additional guidance with regard
to implementation of the bulletin requirements:
Nonconformances
One way of satisfying the requirements of the bulletin is to inspect safety-
related piping systems against the specific revisions of drawings which were
used as input to the seismic analysis. Some architect-engineers (A-E)
however, are recommending that their customers inspect these systems against
the latest revisions of the drawings and mark them as necessary to define
the as-built configuration of the systems. These drawings are then returned
to the AE's offices for comparison by the analyst to the seismic analysis
input. For licensees taking this approach, the seismic analyst will be the
person, who will identify nonconformances.
The first supplement to the bulletin provided guidance with regard to
evaluation of nonconformances. That guidance is appropriate for licensees
inspecting against later drawings. The licensee should assure that he is
promptly notified when the AE identifies a nonconformance, that the initial
engineering judgment is completed in two days and that the analytical
engineering evaluation is completed in 30 days. If either the engineering
judgement or the analytical engineering evaluation indicates that system
operability is in jeopardy, the licensee is expected to meet the applicable
technical specification action statement.
Visual Approximations
Some licensees are visually estimating pipe lengths and other inspection
elements, and have not documented which data have been obtained in that way.
Visual estimation of dimensions is not encouraged for most measurements,
however, where visual estimates are used, the accuracy of estimation must be
within tolerance requirements. Further, in documenting the data, the
licensee must specifically identify those data that were visually estimated.
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IE Bulletin No. 79-14, Supplement 2 September 7, 1979
Page 2 of 2
Thermal Insulation
In many areas, thermal insulation interferes with inspection of pipe support
details, i.e. attachment welds, saddles, support configuration, etc. In some
areas, the presence of thermal insulation may result in unacceptably large
uncertainties for determination of the location of pipe supports.
Where thermal insulation obstructs inspection of support details, the
insulation should be removed for inspection of a minimum of 10% of the
obstructed pipe supports in both Item 2 and 3 inspections. In the Item 3
response, the licensee should include a schedule for inspecting the
remaining supports.
Where necessary to determine the location of pipe supports to an accuracy
within design tolerances, thermal insulation must be removed.
Clearances
For exposed attachments and penetrations, licensees are expected to measure
or estimate clearances between piping and supports, integral piping
attachments (e.g. lugs and gussets) and supports, and piping and
penetrations. Licensees are not expected to do any disassembly to measure
clearances.
Loose Bolts
Loose anchor bolts are not covered by this bulletin, but are covered by IE
Bulletin No. 79-02. Any loose anchor bolts identified during actions taken
for this bulletin should be dispositioned under the requirements of Bulletin
No. 79-02.
Other loose bolts are to be treated as nonconformances if they invalidate
the seismic analysis; however, torquing of bolts is not required.
Difficult Access
Areas where inspections are required by the Bulletin but are considered
impractical even with the reactor shutdown, should be addressed on a case by
case basis. Information concerning the burden of performing the inspection
and the safety consequence of not performing the inspection should be
documented by the licensee and forwarded for staff review.
Schedule
The schedule for the action and reporting requirements given in the Bulletin
as originally issued remains unchanged.
Page Last Reviewed/Updated Tuesday, March 09, 2021