ML20198B022

Insp Repts 50-327/85-29 & 50-328/85-29 on 850820-23. Violations Noted:Inadequate Design Controls for Seismically Designed Cable Tray Support Sys & safety-related Cable Tray Support Baseplate Installations

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: ML20198A974 ML20198A997 ML20198B022
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

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[>* Etcoq'o NUCLEAR REGULATORY COMMISSION

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[ n REGION 11

g ,j 101 MARIETTA STREET N.W.

• 's ATLANTA, GEORGI A 30323

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Report Nos.: 50-327/85-29 and 50-328/85-29

4 Licensee: Tennessee Valley Authority

500A Chestnut Street .

j 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

j Inspection Condu ted: August 20-23, 1985

Inspector: C k N 8

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W. / Date Sign

Approved by;[ . /  : -::- [ b

4'/J/ K Flake, 5 tToJ%Mef - Date Signed

Engineeri ancti

Divi of Reactor Safety

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SUMMARY

[ Scope: This special, unannounced inspection entailed 24 inspector-hours on site

j in the areas of safety-related cable tray support systems, and licensee event

j reports associated with the failure of the chemical and volume control system

j sampling lines.

Results: Two violations were identified - Inadequate design controls for

i seismically designed cable tray support systems, paragraph 5.b; Inadequate design

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controls for safety-related cable tray support baseplate installations,

i paragraph 5.c.

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8511060277 85 025  ;

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PDR ADOCK O 327

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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

determine whether they are acceptable or may involve violations or devia-

tions.

One new unresolved item identified during this inspection is discussed in

f paragraph 6.b.

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j 5. Safety-Related Cable Tray Support Systems

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1 a. Design Document Review l

! The inspector reviewed portions of the following documents pertaining

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to safety-related cable tray support systems to determine whether  !

< appropriate design criteria have been established and whether they

1 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

System, August 20, 1975

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- Design input Memorandum for Design Criteria for Category I Cable

l Tray Supports, May 1, 1985 ,

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CEB 80-16 Dynamic Earthquake Analysis of the Diesel Generator

l Building and Response Spectra for Attached Equipment,

l April 9, 1973

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CEB 80-67, Dynamic Earthquake Analysis of the Additional Diesel i

Generator Building and Response Spectra for Attached Equipment,

! June 24, 1983

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1 - Supplementary Seismic Analysis for the Additional Diesel Generator '

{ Building, August 27, 1981

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CEB Report No. 75338, Static Load Tests of Cable Trays and Support-

, ing Connections, December 4, 1975

b. Design Calculations Review

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l The inspector reviewed portions of the following design calculations

! associated with the safety-related cable trays support systems.

Location Reference Drawing

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Control Building 48N1297, 1298, 1299 and 1300

l Brackets A thru J

Auxiliary Building 48N1363 thru 1369

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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. It

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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l 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. ,

j~ c. Design Drawing Review

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The inspector reviewed portions of the following design drawings

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associated with the cable tray support systems. ,

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Location ,

Drawing Number

• Auxiliary B'uilding 48N1369, Rev. 2

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Reactor Building 48N1505

Control Building 48N1297, 1298, 1300, 1302

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Diesel Generator Buiiding 18N251, 252 and 253

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• Indicates discrepancy identified during the review.

The above design drawings were partially reviewed 'for conformance to

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design analysis and the licensee commitments. The inspector found that-

baseplates with oversize holes were actually used in the installation,

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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

procedure, the correct hole size in a baseplate should be 1/16" larger

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than the nominal bolt size. In this case, the correct hole size in the

baseplate should have been 13/16". The inspector held discussions with

licensee representative with respect to the above concerns. It was

i found that a total number of 16 baseplates inspected, (8 per unit),

! .all were actually installed with each baseplate containing 4 drilled

i holes that were 3/8" larger than the required si.ze. ' It was further

! 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

! violation of 10 CFR 50, Appendix B, Criterion 1:1, and is identified as

l 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.

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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.

i 7. Licensee's Corrective Action

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Subsequent to the inspector's finding with respect to the seismic analysis,

the licensee issued a memorandum on August 23, 1985, stating that TVA has

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1 committed to reanalyze the cable tray supports in the two diesel generator

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:

l a. Civil Project Engineer will be responsible for limiting the performance

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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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