ML20198B022
| ML20198B022 | |
| Person / Time | |
|---|---|
| Site: | Sequoyah  |
| Issue date: | 09/19/1985 |
| From: | Blake J, Liu W NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II) |
| To: | |
| Shared Package | |
| ML20198A979 | List: |
| References | |
| 50-327-85-29, 50-328-85-29, NUDOCS 8511060277 | |
| Download: ML20198B022 (7) | |
See also: IR 05000327/1985029
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UNITED STATES
NUCLEAR REGULATORY COMMISSION
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REGION 11
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101 MARIETTA STREET N.W.
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ATLANTA, GEORGI A 30323
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Report Nos.: 50-327/85-29 and 50-328/85-29
Licensee: Tennessee Valley Authority
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500A Chestnut Street
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Chattanooga, TN 30372
Docket Nos.: 50-327 and 50-328
License Nos.: DPR-77 and DPR-79
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Facility Name: Sequoyah 1 and 2
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Inspection Condu ted: August 20-23, 1985
Inspector:
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Date Sign
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Approved by;[ . /
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4'/J/ K Flake, 5 tToJ%Mef -
Date Signed
Engineeri
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of Reactor Safety
SUMMARY
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Scope:
This special, unannounced inspection entailed 24 inspector-hours on site
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in the areas of safety-related cable tray support systems, and licensee event
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reports associated with the failure of the chemical and volume control system
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sampling lines.
Results:
Two violations were identified - Inadequate design controls for
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seismically designed cable tray support systems, paragraph 5.b; Inadequate design
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controls for safety-related cable tray support baseplate installations,
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paragraph 5.c.
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8511060277 85 025
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REPORT DETAILS
1.
Persons Contacted
Licensee Employees
- P. Wallace, Plant Manager
- L. Nobles, Superintendent, Operations and Engineering
- J. Vineyard, Project Manager
- H. Rankin, Manager, Design Services
- C. Johnson, Civil Project Engineer
- K. Mogg, Section Supervisor, Design Services
- K. Spates, Civil Engineer, Civil Engineering Branch (CEB)
- T. Bucy, Civil Section Supervisor, CEB
- J. Holland, Project Engineer, Site Services
- G. Kirk, Compliance Supervisor
- D. Carven, Quality Assurance Supervisor
L. Katcham, Civil Engineer, CEB
Other licensee employees contacted included engineers, technicians, security
force members, and office personnel.
- Attended exit interview
2.
Exit Interview
The inspection scope and findings were summarized on August 23, 1985, with
those persons indicated in paragraph 1 above.
The inspector described the
areas inspected and discussed in detail the inspection findings.
No
dissenting comments were received from the licensee.
(0 pen) Violation 327, 328/85-29-01, Inadequate Design Controls for
Seismically Designed Cable Tray Support, paragraph 5.b.
(0 pen) Violation 327, 328/85-29-02, Inadequate Design Control for
Safety-Related Cable Tray Support Baseplate Installations, paragraph 5.c.
(0 pen) Unresolved Item 327, 328/85-29-03, Evaluation of the CVCS Sampling
Line Failure, paragraph 6.b.
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The licensee did not identify as proprietary any of the materials provided
to or reviewed by the inspector during this inspection.
3.
Licensee Action on Previous Enforcement Matters
This subject was not addressed in the inspection.
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4.
Unresolved Items
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Unresolved items are matters about which more information is required to
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determine whether they are acceptable or may involve violations or devia-
tions.
One new unresolved item identified during this inspection is discussed in
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paragraph 6.b.
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5.
Safety-Related Cable Tray Support Systems
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a.
Design Document Review
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The inspector reviewed portions of the following documents pertaining
to safety-related cable tray support systems to determine whether
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appropriate design criteria have been established and whether they
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comply with NRC requirements and the licensee commitments.
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Design Criteria No. SQN-DC-V-1.3.4, Category I Cable Tray Support
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System, August 20, 1975
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Design input Memorandum for Design Criteria for Category I Cable
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Tray Supports, May 1, 1985
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CEB 80-16
Dynamic Earthquake Analysis of the Diesel Generator
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Building and Response Spectra
for Attached Equipment,
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April 9, 1973
CEB 80-67, Dynamic Earthquake Analysis of the Additional Diesel
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Generator Building and Response Spectra for Attached Equipment,
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June 24, 1983
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Supplementary Seismic Analysis for the Additional Diesel Generator
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Building, August 27, 1981
CEB Report No. 75338, Static Load Tests of Cable Trays and Support-
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ing Connections, December 4, 1975
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b.
Design Calculations Review
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The inspector reviewed portions of the following design calculations
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associated with the safety-related cable trays support systems.
Location
Reference Drawing
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Control Building
48N1297, 1298, 1299 and 1300
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Brackets A thru J
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Auxiliary Building
48N1363 thru 1369
Reactor Building
48W 952-1 and 952-2
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- Diesel Generator Building
18N251 thru 253
- Additional Diesel Generator Building
18W298-1 and 298-2
- Discrepancies were identified during the review.
The above cable tray support design calculations were reviewed for
conformance to analysis criteria, applicable codes, NRC requirements
and the licensee commitments.
Additionally, these calculations were
evaluated during the review for thoroughness, clarity, consistency, and
accuracy.
In general, the design calculations appeared to be accep-
table with the exception of those for the two diesel generator build-
ings identified below:
(1) Design Calculations for cable tray support mark numbers 9,11,
11A, 31 and 32 in the diesel generator building were reviewed.
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was found that these calculations were performed by using a modal
superposition dynamic computer analysis.
The computer programs
consider only the dynamic modal response in the frequency range of
interest.
There was no consideration given to the effects of
rigid body motion from the response spectrum zero period accelera-
tion (ZPA).
A review of the aforementioned design calculation
revealed that many of the cable tray supports were rigidly or
close to rigidly designed.
As a result, the accelerations gene-
rated from the dynamic analysis were generally small when compared
to the response spectrum peak accelerations.
The use of these
small accelerations alone in the design of the rigid supports for
the cable tray support systems is nonconservative and is inadequ-
ate in terms of NRC requirements.
This can be seen from the
design calculations for cable tray supports mark numbers 31 and
32, where zero acceleration in the X diraction and 0.08g accelera-
tion in the Z direction were generated from the dynamic computer
analysis and were used in the design.
The effects of ZPA or the
ground acceleration had not been considered in the design analysis
when these cable tray supports were rigidly designed.
For operat-
ing basis earthquake (OBE), the response spectrum ZPA or the
ground acceleration (elevation 722'-0") is 0.379 which is the
additional seismic load that should have been considered in the
design analysis.
(2) Design calculations for cable tray support mark numbers 1 and 2 in
the additional diesel generator building were reviewed.
The
inspector noted that the same dynamic computer programs were
utilized in the design analysis.
The effects of ZPA had not been
considered in the design analysis.
The inspector held discussion with licensee representatives
regarding the above concerns.
It was concluded that the effects
of the response spectrum ZPA or the ground accelerations should
have been considered in the design analysis when the supports were
rigidly designed. Since the cable tray supports in the two diesel
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generator buildings were rigidly designed and had not considered
the effects of the response spectrum ZPA, these supports may not
be able to serve their intended function during a seismic event.
The improper design of the cable tray support systems is a viola-
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tion of 10 CFR 50, Appendix B, Criterion III, and is identified as
Violation 327, 328/85-29-01, Inadequate Design C.ortrols for
Seismically Designed Cable Tray Supports.
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c.
Design Drawing Review
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The inspector reviewed portions of the following design drawings
associated with the cable tray support systems.
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Location
Drawing Number
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- Auxiliary B'uilding
48N1369, Rev. 2
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Reactor Building
48N1505
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Control Building
48N1297, 1298, 1300, 1302
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Diesel Generator Buiiding
18N251, 252 and 253
- Indicates discrepancy identified during the review.
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The above design drawings were partially reviewed 'for conformance to
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design analysis and the licensee commitments. The inspector found that-
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baseplates with oversize holes were actually used in the installation,
Design Drawing 48N1369, Rev. 2, specified 1 3/16" diameter holes in the
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baseplates for 3/4" diameter wedge bolts.
In accordance' with TVA
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procedure, the correct hole size in a baseplate should be 1/16" larger
than the nominal bolt size. In this case, the correct hole size in the
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baseplate should have been 13/16". The inspector held discussions with
licensee representative with respect to the above concerns.
It was
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found that a total number of 16 baseplates inspected, (8 per unit),
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.all were actually installed with each baseplate containing 4 drilled
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holes that were 3/8" larger than the required si.ze. ' It was further
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noted that the oversize holes specified on the design drawing was a
design error.
As a result, these 16 baseplates may not be able to
serve their intended function as required bysth'e design.
This is a
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violation of 10 CFR 50, Appendix B, Criterion 1:1, and is identified as
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Violation 327, 328/85-29-02,
Inadequate Design Controls for
Safety-related Cable Tray Support Baseplate Installations.
Within the areas inspected, two violations were identified.
6.
Licensee Event Followup (92700)
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a.
Licensee event status
The~ licensee informed Region II onlfugbst 12, 1985, that a routine
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walkthrough by an auxiliary operator identified a crack through the
weld area of the chemical and volume control system (CVCS) 3/4 inch
sampling line.
The weld crack is almost identical in location to the
one reported by the licensee on Unit 2, on July 30, 1985. The licensee
has completed weld repairs on both units, and pipe supports are being
designed and installed on both branch lines.
Neither of the two branch lines contained supports prior to detection
of the leaks.
The licensee has completed walkdowns of the CVCS lines
in both units, except high radiation areas in containment, and found no
other unsupported branch lines.
Metallurgical analysis of the Unit 2 crack indicated that the failure
mechanism was low stress, and high cycle fatigue. Vibrational analysis
of both lines has not identified the source of any vibration which may
have occurred.
The licensee is continuing to make efforts and to
determine the cause of the failure to the two sampling lines.
b.
Piping Stress and Pipe Support Evaluation
The inspector held discussions with licensee representative regarding
the above concerns.
It was determined that the piping group was to
perform two design analyses.
One was to determine whether a pipe
support was required in accordance with CEB Report 75-18 guidelines,
the other was to determine whether the allowable code stresses were
being met in accordance with the rigorous analysis criteria.
Results
of the two design analyses indicated that no supports were required for
the two sampling lines in terms of meeting the flexibility requirements
and the stress allowable requirements.
The inspector reviewed portions of the aforementioned design analyses
and the design guidelines contained in the CEB Report 75-18.
It was
found that the design analysis on sheet No. 4 contained an error in the
flexibility check in that 0.00045 was shown to be less than 0.0002.
With the error corrected, the design analysis did indicate that a
support was required for the 3/4 inch sampling lines. The above design
analysis had been checked and reviewed by the licensee responsible
engineers prior to the inspector's finding. The inspector held discus-
sions with licensee representatives with regard to the above concern.
It was decided that the licensee's responsible group was to pursue a
further design analysis in that a more detailed analysis was required
to determine whether a support was needed. Pending further evaluations
to be performed by the licensee to determine the cause of the failure
for the sampling line, this matter is identified as Unresolved Item
327,328/85-29-03, Evaluation of the CVCS Sampling Line Failure.
Within the areas inspected, no violations or deviations were identifi-
ed.
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7.
Licensee's Corrective Action
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Subsequent to the inspector's finding with respect to the seismic analysis,
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the licensee issued a memorandum on August 23, 1985, stating that TVA has
committed to reanalyze the cable tray supports in the two diesel generator
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buildings to include the effects of the additional seismic loads that were
associated with the response spectrum ZPA or the ground accelerations.
In
addition, the following actions will be taken:
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Civil Project Engineer will be responsible for limiting the performance
of the dynamic modal analysis to selected qualified individuals,
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b.
The CEB central staff will provide direction and training of the use of
dynamic modal analysis where required.
c.
A design input memorandum will be issued for the cable tray support
design criteria.
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