ML20085B642

Final Deficiency Rept Re Design Deficiency in Portions of Control Rod Drive Sys & Standby Gas Treatment Sys.Initially Reported on 730317.Seismic Analyses of Affected Components Performed

ML20085B642
Person / Time
Site:	Browns Ferry
Issue date:	04/23/1973
From:	Gilleland J TENNESSEE VALLEY AUTHORITY
To:	Kruesi F US ATOMIC ENERGY COMMISSION (AEC)
Shared Package
ML20085B604	List: ML20085B624 ML20085B642
References
10CFR-050.55E, 10CFR-50.55E, NUDOCS 8307080232
Download: ML20085B642 (3)

Text

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TENNESSEE VALLEY AUTHORITY CH ATTANOOG A, TENNESSEE 37401 April 23,1773

[O'3 5Y "Glt) ~ p 9 6 N Mr. F. E. Krucsi, Director Directorate of Regulatory Operations U.S. Atomic Energy Commission Washington, DC 20545 ..

Dear Mr. Kruesi:

On March 13, 1973, TVA notified Region II DRO office by telephone of what was believed to be a reportable design -

deficiency in two systems of the Browns Ferry Nuclear -

Plant. In accordance with paragraph 50.55(e) of --

10 CFR 50, we are submitting the enclosed formal report of the design deficiency which was related to the adequacy of the two systems to meet seismic Class I .-

criteria.

Very truly yours, _; -

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4 J. E. Gilleland -

Assistant to the Manager of Power Enclosure CC (Enclosure): -

Mr. Norman C. Moseley, Director Directorate of Regulatory Operations '

U.S. Atomic Energy Commission -

Region II - Suite 818 230 Peachtree Street, NW.

Atlanta, Georgia 30303 o 6 ) 1 {'

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FINdL DEFICIENCY REPORT .

ON .

CONTROL ROD PR1W. AND GTAmnY GA9 TPEATMF.!!T SYSTEMS i

e During a review of seismic documentation for the Brouno Ferry Nuc1 car Plant, we found that portions of the CRD system and portions of the Standby Cas Treatment System were not designed to seismic Class I criteria as required by' the design bases and as stated in the Fluul, -

l Although the specifications for the design,' fab'Irication, and installation required the CRD System to be scismic Class I, the piping supports , [

• were not scismically analyzed nor were the hydraulic control unit (HCU) anchors and the scram discharge volume tank mountings. Even though TVA recognized that the commitment existed, this requirement was not cnforced as a result of an oversight for the TVA scope of supply components.

However, the Concral Electric Company . scope'of supply components, such as the control rods, CRD mechanisms, scrma level instrumentation, and the individual ECU's, were seismically qualified and documentation of their ,

qualification is availabic. ,

If the deficiency had not been discovered, it could have icd to a failure-of the reactor to scram for some few reactor conditions in combination with

, certain highly unlikely postulated distortions in the CRD piping resulting from carthquakes. For such combinations, the ATWS reactor protection system would have terminated the transient and reduced _rcactor power to a low

. Icvel. Then the standby liquid control system would have been initiated 1 'I to shut dmnt and maintain the reactor in a safe condition. For the more I

' probabic reactor conditions and postulated CRD piping failures,, the control rods would have scrs=ned to shut down the reactor. The control rods would have latched and remained in place to maintain the reactor in a safe condition. .

, Laacdiately upon discovery, a progrcm was ' initiated to correct thid '

, deficiency. Analyses were performed for the supports on 2-inch, schedule 160 g" and larger piping, HCU anchors, and scram volume tank mountings to determine their capability to withstand carthquake loadings. Some additional restraints were added in order for these pipes'to meet scismic Class I requircran ta. The 2-inch-and-under pipes are supported in accordance with

" Criteria for Seismically Qualifying Field Run' Piping (Sizes 1/2 through -

2 Inches)." This criteria was prepared and approved b'y TVA Division of I

Engineering Design for scismic qualification of {small lines in scismic Class I systems. All field podifications for Unit I will be completed before fuel loading occurs.  ; I! j itl I-i t 3

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,  ; 'j h- Although design criteria for the SGTS required that it be seismically ,

'qualifi*cd, an oversight permitted portions of the system to be designed -;

without providing adequate documentation of its scismic design status.

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The filter train was purchased to scismic Class I requirements and documentation is availabic showing that it meets: these requirements. The i . remainder of the system such as fans, ducts, dam'pers, and instrumentation ,

were not analyzed or tes ted as class I equipment. -  ! .

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If the deficiency had not bocn discovered, the Standby Gas Treatment j '- -- System might have -bcen inoperabic follouing an carthquake which is

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. ar.sumed to occur coincident with a LOCA.. Thus, primary containment t

Icakage would not have received adequate treatment for this design -

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- Subsequent scismic analyses of the fans, ducts,'and dampers, and scismic

.' testing of the instrumentation for the Standby Gas Treatment System have

! shown these components to be scismically qualified :to meet. scismic. Class I criteria. Thus, no hardware changes varc required to correct this design defidiency; only design documentation was required. Adequate documentation

-I is now availabic that shows the.SGTS is designed' as a scismic. Class I

] cystem. , .

, 1: The deficiencies defined herein were uncovered;during a revicu of seismic

,3l documentation. Our revicw is continuing and will be complete prior to j} ,

fuc1 loading.  ;'

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. Subsequent to the occurrence of these deficiences TVA's quality assurance

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,  ; program for design end construction has been reorganized and strengthened ,

, - {- ,I to conform to 10 CFR 50 Appendix B. This provides assurance'that such

,j.; instances will riot occur again.

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