United States Nuclear Regulatory Commission - Protecting People and the Environment

Information Notice No. 83-24: Loose Parts in the Secondary Side of Steam Generators at Pressurized Water Reactors

                                                           SSINS No.:  6835 
                                                           IN 83-24        

                               UNITED STATES 
                       NUCLEAR REGULATORY COMMISSION 
                    OFFICE OF INSPECTION AND ENFORCEMENT 
                           WASHINGTON, D.C. 20555 
                                     
                               April 28, 1983 

Information Notice No. 83-24:   LOOSE PARTS IN THE SECONDARY SIDE OF 
                                   STEAM GENERATORS AT PRESSURIZED WATER 
                                   REACTORS 

Addressees: 

All pressurized water reactors (PWRs) holding an operating license (OL) or a 
construction permit (CP). 

Purpose: 

This information notice is provided as a notification of a potentially 
significant problem pertaining to loose parts on the secondary side of steam
generators. It is expected that recipients will review the information for 
applicability to their facility. No specific action or response is required 
at this time. 

Description of Circumstances: 

Licensees and applicants have previously been provided copies of NUREG-0909 
and NUREG-0651 which describe the circumstances of the loose parts related 
tube rupture events at R. E. Ginna and Prairie Island 1, respectively. As a 
result of these events, the staff is evaluating the need for additional 
requirements to ensure the detection and prevention of loose parts as part 
of the ongoing NRC Generic Program Concerning Steam Generator Tube 
Degradation and Rupture Events. In the meantime, the staff is continuing to 
receive reports that loose parts and foreign objects are being found in 
steam generators. These occurrences have involved both operating plants and 
plants under construction. Some of the most significant of these occurrences 
are described in this information notice. 

During a December 20-22, 1982 inspection of steam generators at Wolf Creek, 
Kansas Gas and Electric Company reported finding a 1.88-lb metal wedge (1" x 
1 1/2" x 3") in the secondary side of the B steam generator and a 2.8-oz, 6" 
flat file in the secondary side of the C steam generator. Additionally, 
debris consisting of grit, rust, sponge particles, wire bristles, and pieces
of wood were found throughout the secondary side of the steam generators. It
was not determined whether the loose parts and debris remained after 
fabrication or were introduced into the steam generators during 
installation. 

During visual inspections (using fiber optics) in March 1983, TVA discovered
loose material on the secondary side of the Watts Bar 1 steam generators 
including nuts, bolts, a grinder wheel, and "crystalline deposits." 
.

                                                          IN 83-24        
                                                          April 28, 1983  
                                                          Page 2 of 3     

On February 25, 1982, Zion 1 discovered two 30 inch steel hinges and 36 
nut-bolt-washer assemblies in the channel head plenum area (primary coolant 
side) of a steam generator while preparing for  eddy current testing. The 
hinges and fasteners were part of a cover left in the steam generator from a 
previous inspection. About 1100 protruding tube ends were damaged by the 
hinge preventing the passage of the eddy current probe. Extensive repairs 
were required. 

Five broken steam generator wrapper support bars (2" diameter by about 6" 
long) were found at San Onofre 1 during a visual inspection of the secondary
side of the steam generators using a remote camera in Spring of 1982. 
Several other pieces of metal fragments and other debris were found.  The 
visual inspection indicated no evidence of significant damage to the 
peripheral tubes. Some peripheral tubes exhibited ID indications or 
restrictions during eddy current testing and were plugged as a conservative 
measure. 

Turkey Point 4 developed primary to secondary steam generator leakage on 
July 6, 1982. Using fiber optics and eddy current testing, an inspection of 
the entire periphery of the tube bundle was performed. Minor tube damage and 
the following foreign objects were found in the secondary side of steam 
generator B: 1 check valve pin, 1 threaded rod with wingnut, 1 metal plate 
1/2"x2"x6", 1 weld rod, 1 bolt for check valve pin, 1 socket, 1-5" wire, and 
1 flat piece of metal 3/8"x2"x1.5". Similar objects were found on the 
secondary side of steam generators A and C. 

Similar discoveries were made in the secondary side of the D.C. Cook Unit 1 
steam generators when they were inspected during a refueling outage in July 
of 1982 except that no tube damage was detected. Objects found included a 6"
diameter ball of 1/16" wire; 2 bronze lock nuts-1" across the flats x 
1/16"1/8" thick; 2-3/8" x 1-1/2" cap screws with two nuts, wired together; 
metal spatter, size of a half dollar; and parts of a pocket knife consisting
of 1 piece of metal 1/2" x 1-1/8" x 1/16" and 1 piece 1/2" x 4." 

Visual inspection of the secondary side of the Point Beach steam generators 
in November 1982 revealed a large (6") C-clamp, a 58" long bar (1/2" x 3/8" 
cross section), and other loose objects. The C-clamp was found leaning 
against two tubes which showed definite signs of mechanical damage. These 
tubes had developed leakage in 1978 and had been plugged. 

Loose parts have been implicated in two of the four tube rupture events in 
operating plants. In addition to tube ruptures, loose parts in the secondary
side of steam generators of at least two plants have resulted in tube 
damage. In most cases, the loose parts have been found before sufficient 
damage had occurred to cause leakage or rupture. However, the consequences 
of loose parts do present some risk to public health and safety as well as 
undesirable economic consequences. Therefore, it is prudent to avoid this 
problem.  (See also INPO SOER 82-12, "Steam Generator Tube Ruptures Caused 
by Loose Parts on the Secondary Side," which contains information and 
recommendations for operating plants which may be applied appropriately to 
plants under construction.)  
.

                                                          IN 83-24        
                                                          April 28, 1983  
                                                          Page 3 of 3     

If you have any questions regarding these matters 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:  M. S. Wegner 
                    301-492-4511 

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