United States Nuclear Regulatory Commission - Protecting People and the Environment

Information Notice No. 84-48, Supplement 1: Failures of Rockwell International Globe Valves

                                                     SSINS No.: 6835       
                                                     IN 84-48, Supplement 1 

                                UNITED STATES
                        NUCLEAR REGULATORY COMMISSION
                    OFFICE OF INSPECTION AND ENFORCEMENT
                           WASHINGTON, D.C. 20555

                              November 16, 1984

Information Notice No. 84-48, SUPPLEMENT 1:   FAILURES OF ROCKWELL 
                                             INTERNATIONAL GLOBE VALVES 

Addressees: 

All nuclear power reactor facilities holding an operating license (OL) or a 
construction permit (CP). 

Purpose: 

This information notice supplement is provided as a notification of 
additional information concerning the failures of Rockwell International 
globe valves. It is expected that recipients will review the information for
applicability to their facilities and consider actions, if appropriate, to 
preclude similar problems occurring at their facilities. However, 
suggestions contained in this information notice do not constitute NRC 
requirements and, therefore, no specific action or written response is 
required. 

Background: 

Information Notice No. 84-48 described a number of Rockwell International 
valve failures at Salem Generating Station Units 1 and 2. In describing 
these failures, it does not clearly indicate that there were two different 
modes of failure, each with its unique cause. 

Discussion: 

The first of these failures was identified in the reactor coolant loop 
resistance temperature detector (RTD) bypass line valves at Salem Generating
Station Units 1 and 2 [licensee event reports (LERs) 84-010 dated May 1, 
1984, and 84-001 dated February 9, 1984; respectively]. The mode of failure 
was the separation of the disk from the stem. The cause of the failure was 
stress corrosion cracking of the stem resulting from high stresses indicated
as being due to excessive backseating forces. Rockwell International's 
recommendation for controlling this type of failure is to limit the 
backseating force which the valve experiences. 

The second failure was identified in the safety injection system flow 
throttling valves at Salem Generating Station Unit 1 (LER 84-012 dated June 
26, 1984). This LER also addressed a similar finding at Unit 2. The mode of 
failure was partial unthreading of the disk from the disk nut. The cause of 
the failure 


8411150072 
.

                                                     IN 84-48, Supplement 1 
                                                     November 16, 1984     
                                                     Page 2 of 2           

was initially reported as the absence of the weld metal deposit that 
attaches the disk to the disk nut through a small hole in the disk. However,
information received from the manufacturer indicates that the process of 
attaching the disk to the disk nut is not through the addition of weld 
metal, but rather through the use of a tungsten inert gas arc to thermally 
upset the threads on the disk nut opposite the small hole in the disk. 
Examination by the manufacturer indicated that the thermal upset had either 
fractured or been deformed by the disk rotating over the thermal upset area. 
The torque, necessary to fracture or deform the thermal upset, is attributed 
to the high cavitation loads that the valve disk experienced when used in 
severe throttling conditions. Rockwell International's recommendation for 
controlling this type of failure is to replace any such valve used for 
severe throttling with one of a smaller size so that the valve disk will be 
in a mid-position or a more fully open position at the required flow. 

No specific action or written response to this information notice supplement
is required. If you have any questions about this matter, please contact the
Regional Administrator of the appropriate NRC Regional Office, or this 
office. 



                                   Edward L. Jordan Director 
                                   Division of Emergency Preparedness 
                                     and Engineering Response 
                                   Office of Inspection and Enforcement 

Technical Contact:  R. J. Kiessel, IE
                    (301) 492-8119

Attachment:
List of Recently Issued IE Information Notices
Page Last Reviewed/Updated Tuesday, November 12, 2013