ML20058N676

Discusses Action Item 5 Assigned in 880406 Memo Related to Diagnostic Evaluation Team Report for Plant on Pump Damage Due to Low Flow Cavitation

ML20058N676
Person / Time
Site:	Mcguire, McGuire
Issue date:	10/18/1988
From:	Novak T NRC OFFICE FOR ANALYSIS & EVALUATION OF OPERATIONAL DATA (AEOD)
To:	Jordan E NRC OFFICE FOR ANALYSIS & EVALUATION OF OPERATIONAL DATA (AEOD)
Shared Package
ML17160A485	List: ML20058J942 ML20058N676 ML20058N934 NUREG-1339, Summarizes Resolution of GI 29 Bolting Degradation or Failure in Nuclear Power Plants NUREG-1365, Discusses Three Issues Currently Being Tracked by Generic Issue Mgt Control Sys.Issues Include Behavior of Severely Damaged Fuel,Behavior of Core Melt & Effect of Hydrogen Combustion on Containment Structures NUREG-1453, Discusses Resolution of GI 142 Re Leakage Through Electrical Isolators.Draft NUREG-1453, Regulatory Analysis for GI 142, 'Leakage Through Electrical Isolators in Instrumentation Circuits,' Encl NUREG-1461, Discusses Resolution of GI 153 Re Loss of Essential Svc Water in Lwrs.Insights from Study Will Be Informative to on-going Programs & Will Be Published as NUREG-1461
References
RTR-NUREG-0933, RTR-NUREG-933 AEOD-E807, NUDOCS 9312220206
Download: ML20058N676 (2)

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UNITED STATES NUCLEAR REGULATORY COMMISSION 1 E 'I wasmuorow,o c. osss 3 i":~ ~ b' "

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MEMORANDUM FOR: - Edward L. Jordan, Director AE00/E807 Office for Analysis and Evaluation of Operational Data e FPCM: Thomas M. Novak, Director Et Division of Safety Programs.

Office for Analysis and Evaluation j of Operational Data >

ENGINEERING EVALUATION REPORT - PUMP DAMAGE DUE SUEJECT:

TO LOW FLOW CAVITATION ]

This memorandum and the enclosed report are our response to action item 5-

. assi gne d by the EDO in.his memorandum dated April 6, 1988, related to the ..

p" diagnostic evaluation team report for McGuire Nuclear Station. This ~

action- -

l item requested thr.t AE00~ corduct an evaluation of' insufficient pump mini-flow recirculation problem and-determine: (1) if a potential generic issue-~ exists, and (2) if generic communications are warranted. .

l This evaluation incicates that cperation of centrifugal pumps at a:certain  :

range of flows below the design flows, can create flow recirculation'in3ide the- '

pumps. These internal. recirculations' induce cavitation, hydraulic pressure:

-pulsation and vibration which can cause damage to the pumps following an' extended period ofl operation at.such low flows. The pump mini-flow recircula--  :

. tion lines have traditionally been sized solely on the basis of pumpIfluid; j temperature-rise. Temperature rise is not the only factor influencing safe,  !

continuous minimum flow-operation, and thus the flow rate may not be1 sufficient _ i to avoid' damage due~to internal recirculation. In' addition, the recirculation configuration may not ha,v.e'been fully considered for pumps. designed for a: wide >

range of flows. Since maily.of the safety-related cooling system pumps. in most A operating plants are designed to operate with a wide range of flows and use a'. ,

1 mini'-flow line for inservice' testing for pumps and/or for protection againsti .

operation of pumps at shutoff heads, there is' the potential that some: pumps may - ~

be run at a low flow within the recirculation zone, without;the . awareness of :

the plant operators. Our review has identified cases in which major, 3

degradation of impe11ers and"casi_ngs have, occurred to centrifuga1' pumps. 1 running. continuously at low flows.  !

2 Near the completion of this study, NRR issued Bulletin 88-04', ." Potential l Safety . '

Related Pump Loss," on May- 5,11988 which addressesicertain aspects of'the' 3 D

internal-recirculation problem. The: actions addressed in the bulletin appear 'I specific to the. mini-flow line. However, this evaluation has found that the; .

pump damage induced.by internal recirculation can.'also be caused by operating '

' pumps: at: low flow. By separate memorandum, the enclosed AEOD report and.

suggestions have been forwarded to NRR for further action. _

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99312220206;931129 PDR NUREO- '

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Edward L. Jordan I I would be pleased to provide any clarification or further infonnation that you may desire.

,/

I Thomas M. Novak, Director Division of Safety Programs Office for Analysis and Evaluation of Operational Data

Enclosure:

As stated cc w/ enclosures: .

C. Heltemes Distribution: -

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JFarlow MTaylor DCC P3)Ps

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