Information Notice No. 89-01: Valve Body Erosion
NUCLEAR REGULATORY COMMISSION
OFFICE OF NUCLEAR REACTOR REGULATION
WASHINGTON, D.C. 20555
January 4, 1989
Information Notice No. 89-01: VALVE BODY EROSION
All holders of operating licenses or construction permits for nuclear power
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.
The valve bodies that have been ultrasonically tested indicate that the minimum
measured wall thicknesses are approaching the minimum code allowable
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
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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
Charles E. Rossi, Director
Division of Operational Events Assessment
Office of Nuclear Reactor Regulation
Technical Contact: Frank J. Witt, NRR
Attachment: List of Recently Issued NRC Information Notices
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
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.
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
88-96 Electrical Shock Fatalities 12/14/88 All holders of OLs
at Nuclear Power Plants or CPs for nuclear
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
88-93 Teletherapy Events 12/2/88 All NRC medical
OL = Operating License
CP = Construction Permit
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