United States Nuclear Regulatory Commission - Protecting People and the Environment

Information Notice No. 81-19: Lost Parts in Primary Coolant System

                                                            SSINS No.: 6835 
                                                            Accession No.: 
                                                            8103300399     
                                                            IN 81-19       

                                UNITED STATES
                        NUCLEAR REGULATORY COMMISSION
                    OFFICE OF INSPECTION AND ENFORCEMENT
                           WASHINGTON, D.C. 20555
                                     
                                July 6, 1981

Information Notice No. 81-19:   LOST PARTS IN PRIMARY COOLANT SYSTEM 

Description of Circumstances: 

During an outage for turbine maintenance, Public Service Electric and Gas 
Company elected to drain the primary system at Salem Unit 1 to about the 
midplane of the hot leg nozzles and open two steam generators in an attempt 
to locate the source of an intermittent series of impacts that had been 
recorded on the Metal, Impact Monitoring System (MIMS) during operation. Not
finding the source, an additional attempt to search the loops was made by 
floating a TV camera, suspended from a foam float, down the hot legs. 

The camera was successfully retrieved from one steam generator, whose hot 
leg does not have a connection for residual heat removal (RHR) suction. 
Retrieval from a second steam generator, whose hot leg does have a 3000 gpm 
RHR suction flow, proved impossible until the RHR flow was turned off 
temporarily. Successful retrieval was further compounded by thermal wells 
protruding into the hot leg. Upon retrieval of the camera float, the 
following parts were missing: 1) a five-inch long by one-inch diameter 
stainless steel tube containing lenses and a lens positioning motor; 2) a 
three-inch long plastic extension tube; 3) a three-inch length of 3/8-inch 
plastic tubing; 4) a short length of nylon line; and 5) a piece of float 
material. Most of these parts were later found in the RHR heat exchanger and
heat exchanger bypass valve, downstream of the RHR pump which was not 
damaged when it chopped the five-inch long stainless tube into two shorter 
tubes. 

While exhaustive efforts to resolve the cause of MIMS impacts are desirable 
and commendable, careful planning should precede placing any additional 
foreign material into the primary system. A detailed inventory of all such 
material should be maintained, and special precautions should be taken to 
prevent the generation of loose parts in the system. In the above example, a 
thorough analysis regarding effects of the RHR flow on the equipment could 
have prevented the potential safety problems that resulted from this event. 

No written response to this information notice is required. If you need 
additional information regarding this matter, contact the Director of the 
appropriate NRC Regional Office. 

Attachment:
Recently issued IE Information Notices 

Page Last Reviewed/Updated Tuesday, November 12, 2013