Information Notice No. 90-26: Inadequate Flow of Essential Service Water to Room Coolers and Heat Exchangers for Engineered Safety-Feature Systems

                                UNITED STATES
                           WASHINGTON, D.C.  20555

                               April 24, 1990

                                   WATER TO ROOM COOLERS AND HEAT EXCHANGERS 
                                   FOR ENGINEERED SAFETY-FEATURE SYSTEMS


All holders of operating licenses or construction permits for nuclear power 


This information notice is intended to alert addressees to potential 
problems resulting from using the wrong flow and pressure drop relationship 
in establishing adequate flow of essential service water to room coolers for 
engineered safety-feature systems and from failing to establish or maintain 
balanced flows in essential service water systems.  It is expected that 
recipients will review the information for applicability to their facilities 
and consider actions, as appropriate, to avoid similar problems.  However, 
suggestions contained in this information notice do not constitute NRC 
requirements; therefore, no specific action or written response is required.

Description of Circumstances:

On March 9, 1990, the reactor at the Clinton Power Station was in cold 
shutdown, and the licensee was taking action to implement the 
recommendations contained in Generic Letter 89-13, "Service Water System 
Problems Affecting Safety-Related Equipment."  The licensee discovered that 
the flow of essential service water being supplied to several room coolers 
serving safety-related equipment was approximately half of the design flow.  
The safety-related equipment included components in the high-pressure and 
low-pressure core spray systems, the low-pressure injection system, the 
residual heat removal system, the standby gas treatment system, the 
combustible gas control system, and the nuclear protection system.  After 
discovering the problem, the licensee declared these systems to be 
inoperable.  The room coolers were supplied to the Clinton Power Station by 
American Air Filter, a subsidiary of Snyder General Corporation.

Before initial operation of the Clinton Power Station, the licensee obtained 
the relationship of the flow and pressure drop on the water side of the room 
coolers from the supplier.  Plant personnel adjusted valving to establish 
the pressure drop across each room cooler which would provide the design 
flow.  Plant personnel did not actually measure the flow to each room 


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On March 9, 1990, the licensee discovered that the relationship between flow 
and pressure drop for the room coolers was wrong and that flows of essential 
service water to the room coolers were too low.  Subsequently, the licensee 
also found that the flows of essential service water to several other 
coolers and heat exchangers were too low.  

To balance the flow of essential service water through the system, plant 
personnel measured the flow using qualified instrumentation and adjusted 
flows to the room coolers according to these measurements.  In some 
instances, the adjusted flows to specific components were somewhat less than 
design flows.  However, the licensee is performing analyses to determine 
whether these flows are acceptable.  Modifications to the updated final 
safety analysis report will be submitted as necessary.


American Air Filter has supplied room coolers to approximately 50 nuclear 
power plants including the Clinton Power Station.  The room coolers consist 
of bundles of folded tubes with supply and return headers at the ends of the 
tubes.  American Air Filter supplies the room coolers either with or without 
pairs of cleanout plugs at the bends in the tubes.  At design flow, room 
coolers with cleanout plugs have a significantly greater pressure drop 
across the tube bundle than room coolers without cleanout plugs.  

On April 3, 1990, Illinois Power Company, licensee for the Clinton Power 
Station, stated in a report submitted to NRC under 10 CFR 21.21 that 
pressure drop data provided by American Air Filter for 22 of 23 room coolers 
was incorrect.  Twenty-two room coolers had cleanout plugs while the 23rd 
room cooler did not.  On April 5, 1990, Illinois Power Company submitted a 
licensee event report which indicated that actual flows for the room coolers 
with cleanout plugs ranged from 10 percent to 80 percent less than the 
design flows.

The licensee event report also indicated that 7 of 25 cooling components 
provided by vendors other than American Air Filter and connected to the 
essential service water system had flows that were less than the design 
flows.  For these cooling components, actual flows ranged from 2 percent to 
42 percent less than the design flows.  The components include: two residual 
heat removal (RHR) heat exchangers supplied by General Electric Company, two 
RHR pump seal coolers supplied by Byron Jackson, a switchgear heat removal 
condenser supplied by Carrier Corporation, a fuel pool cooling and cleanup 
heat exchanger supplied by Yuba Heat Exchanger, and a standby gas treatment 
system radiation monitor cooler supplied by Sentry Equipment Corporation.  
Other components served by the essential service water system were receiving 
excess flow.  These flows ranged up to 213 percent more than design flows.  

Failure to properly balance flows of essential service water during pre-
operational testing or failure to maintain balanced flows can lead to 
degradation of safety-related equipment.

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This information notice requires no specific action or written response.  If 
you have questions about the information in this notice, please contact the 
technical contact listed below or the appropriate NRR project manager.

                             Charles E. Rossi, Director
                             Division of Operational Events Assessment
                             Office of Nuclear Reactor Regulation

Technical Contact:  Roger W. Woodruff, NRR
                    (301) 492-1180

Attachment:  List of Recently Issued NRC Information Notices

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