ML20247J922

Forwards AEOD Engineering Evaluation Rept, Diversion of Seal Cooler Flow for RHR Pumps. Design Deficiencies Similar to Others Reported in Info Notices on Inadequate NPSH in ECCS When One Pump Svcs Two Trains of Components

ML20247J922
Person / Time
Site:	Haddam Neck File:Connecticut Yankee Atomic Power Co icon.png
Issue date:	09/18/1989
From:	Novak T NRC OFFICE FOR ANALYSIS & EVALUATION OF OPERATIONAL DATA (AEOD)
To:	Rossi C Office of Nuclear Reactor Regulation
Shared Package
ML20247J926	List: ML20247J922 ML20247J950
References
AEOD-E907, NUDOCS 8909210028
Download: ML20247J922 (1)

Text

{{#Wiki_filter:_ _ - - _ _ - . t SEP 181989 ~ MEMORANDUM FOR: Charles E. Rossi, Director

                                                ' Division of Operational Events Assessment 0ffice.of Nuclear Reactor Regulation FROM:               Thomas Novak, Director Division of Safety Programs i                                                 Office for Analysis and Evaluation of Operational Data

SUBJECT:

DIVERSION OF SEAL COOLER FLOW'FOR RHR PUMPS Enclosed is an Engineering Evaluation Report on the div'ersion of seal cooler flow for RHR' pumps.. The diversion occurred because' the service water system at Haddam Neck was not hydraulically balanced so that one branch (part of a' train) could feed two RHR seal coolers and two RHR heat exchangers simultane-ously. Sufficient flow was diverted to the second RHR heat exchanger (given the .inoperability of the redundant service water branch) that there was a signi-ficant flow reduction in the RHR pump seal cooler flow. Loss of seal cooler flow would eventually cause failure of both RHR pumps which are required for i long term heat removal following a LOCA. A survey of other PWRs indicates that the Hadda'n Neck piping arrangement may be unique because it switches piping configuration for long term cooling

                           -following a LOCA to use service water rather than component cooling water to cool the RHR heat exchangers and seal coolers. However, it is not obvious from our survey that a similar diversion could not occur following the single failure of a component cooling water train or a service water train in those                                                                               .

plants where ECCS pump cooling and RHR heat exchanger cooling are provided by the same auxiliary water system. This design deficiency is similar to others reported in information notices on L inadequate NPSH in ECCS when one pump services two trains of components. Consequently, we believe it is prudent to alert other licensees to the design flaw discovered at Haddam Neck. We have enclosed a draft information notice to help disseminate this information. If you have any questions, please contact S. Israel (X24437) for additional information. Ip/ Thomas Novak, Director Division of Safety Programs ( mmo Office for Analysis and Evaluation of Operational Data 50' c8

Enclosure:

As stated N Distribution: O ce  % Central;Fjles, ~ EJordan SIsrael l @ ROAB'R/F JHeltemes KBlack  : i oo DSP R/F VBenaroya MWilliams j 7 PDR JRosenthal MTaylor h o.o TNovak Plam qd-{ ,$

      "A                                         ROAB:DSP:                                                                                                     DSPiAE0D         :AE0D ROAB:DSP:AEOD                                                          D       ROA&:DSP:AE0D                                                   .

SIsrael:md % Plam M JRosenthal VBenaroya vak 5 /))/89 g /3J/89 q/(L/89 ")/g/89 cf/g/89 _ _ _ _ _ _ _ - _ _ _ _ - _ - _ _ _ - _ _ . _ _ _ - _ _ _ _ - - _ _ _ _ _ _ - _ _ _ -}}