United States Nuclear Regulatory Commission - Protecting People and the Environment

Information Notice No. 89-01: Valve Body Erosion

                                  UNITED STATES
                         NUCLEAR REGULATORY COMMISSION 
                      OFFICE OF NUCLEAR REACTOR REGULATION 
                            WASHINGTON, D.C.  20555 

                                January 4, 1989 


Information Notice No. 89-01:  VALVE BODY EROSION 


Addressees:

All holders of operating licenses or construction permits for nuclear power 
reactors. 

Purpose:

This information notice is provided to alert recipients to a potential generic
problem pertaining to erosion found in carbon steel valve bodies in safety-
related systems.  It is expected that recipients will review the information 
for applicability to their facilities and consider actions, if appropriate, to
preclude a similar problem.  However, suggestions contained in this notice do
not constitute NRC requirements; therefore, no specific action or written
response is required.

Description of Circumstances:

During the Brunswick Steam Electric Plant, Unit 1 refueling outage, 
inspections performed on December 13, 1988, indicated areas of significant but 
localized erosion on the internal surfaces of several carbon steel valve 
bodies.  The affected safety-related globe valves were the 24-inch RHR/LPCI 
system injection and 16-inch suppression pool isolation valves.  Subsequent 
ultrasonic testing of identical valves on Unit 2, which was operating at 
power, indicated similar erosion.  Additional valves used for throttling 
service (such as high pressure coolant injection) have indicated less erosion 
possibly due to the fact that they have seen less service. 

Discussion:

The valve bodies that have been ultrasonically tested indicate that the minimum
measured wall thicknesses are approaching the minimum code allowable 
thicknesses. 

                         Minimum Wall Thickness - inches

     Valve               Unit 1         Unit 2    Code Allowable      Nominal 

RHR/LPCI Train A          2.7            2.6           1.47             4 

RHR/LPCI Train B          1.7            1.9           1.47             4 

Suppression Pool Train A  N/A            0.8           0.49             2 

Suppression Pool Train B  0.7            0.6           0.49             2 

8812300119
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                                                            January 4, 1989
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The obvious safety concern is that continued operation without weld repair or
replacement could lead to rupture of safety-related valve bodies. 

The root cause assessment of this erosion phenomenon has not been finalized.  
The licensee currently believes that the erosion may have resulted from 
throttling the globe valves below their design flow range.  Excessive 
throttling can promote cavitation which enhances internal valve body erosion. 

A similar problem appears to be occurring at Hatch Unit 1.  On November 17, 
1988, a severe banging noise was heard coming from the line which connects the 
"B" loop of the RHR system to the Condensate Storage and Transfer System.  At 
the time, the "B" loop of RHR was in the shutdown cooling mode.  Further 
investigation revealed that the cause of the banging was cavitation of the 
24-inch RHR/LPCI system injection globe valve.  The Unit 1 shift supervisor 
took action to alleviate the problem by repositioning the valve to increase 
the flow rate, thus reducing the cavitation.  Examination of the valve body 
wall thickness has not been reported to date. 

Past Related Generic Communications:

Information Notice No. 88-17, "Summary of Responses to NRC Bulletin 87-01,
'Thinning of Pipe Walls In Nuclear Power Plants'," dated April 22, 1988, 
provides additional information on erosion downstream of turbine-driven 
reactor feedwater pump minimum-flow control valves.  LaSalle Unit 1 
experienced through-wall erosion in the expander directly downstream of the 
cone-shaped disc in the minimum-flow control valve. 

No specific action or written response is required by this information notice.
If you have any questions about this matter, please contact the technical 
contact listed below or the Regional Administrator of the appropriate regional 
office. 




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

Technical Contact:  Frank J. Witt, NRR
                    (301) 492-0823

Attachment:  List of Recently Issued NRC Information Notices
.                                                            Attachment 
                                                            IN 89-01
                                                            January 4, 1989
                                                            Page 1 of 1

                             LIST OF RECENTLY ISSUED
                            NRC INFORMATION NOTICES 
_____________________________________________________________________________
Information                                  Date of 
Notice No._____Subject_______________________Issuance_______Issued to________ 

88-46,         Licensee Report of Defective  12/30/88       All holders of OLs
Supp. 2        Refurbished Circuit Breakers                 or CPs for nuclear
                                                            power reactors.

88-101         Shipment of Contaminated      12/28/88       All holders of OLs
               Equipment between Nuclear                    or CPs for nuclear
               Power Stations                               power reactors.

88-100         Memorandum of Understanding   12/23/88       All major nuclear
               between NRC and OSHA                         materials licensees
               Relating to NRC-licensed                     and utilities 
               Facilities (53 FR 43950,                     holding CPs and 
               October 31, 1988)                            OLs. 

88-99          Detection and Monitoring      12/20/88       All holders of OLs
               of Sudden and/or Rapidly                     or CPs for PWRs.
               Increasing Primary-to-
               Secondary Leakage

88-98          Electrical Relay Degradation  12/19/88       All holders of OLs
               Caused by Oxidation of                       or CPs for nuclear
               Contact Surfaces                             power reactors.

88-97          Potentially Substandard       12/16/88       All holders of OLs
               Valve Replacement Parts                      or CPs for nuclear
                                                            power reactors.

88-96          Electrical Shock Fatalities   12/14/88       All holders of OLs
               at Nuclear Power Plants                      or CPs for nuclear
                                                            power reactors.

88-95          Inadequate Procurement        12/8/88        All holders of OLs
               Requirements Imposed by                      or CPs for nuclear
               Licensees on Vendors                         power reactors.

88-94          Potentially Undersized        12/2/88        All holders of OLs
               Valve Actuators                              or CPs for nuclear
                                                            power reactors.

88-93          Teletherapy Events            12/2/88        All NRC medical
                                                            licensees.
_____________________________________________________________________________
OL = Operating License
CP = Construction Permit 

Page Last Reviewed/Updated Tuesday, November 12, 2013