United States Nuclear Regulatory Commission - Protecting People and the Environment

Information Notice No. 84-53: Information Concerning the Use of Loctite 242 and Other Anaerobic Adhesive/Sealants

                                                           SSINS No. : 6835 
                                                           IN 84-53        

                                UNITED STATES
                        NUCLEAR REGULATORY COMMISSION
                    OFFICE OF INSPECTION AND ENFORCEMENT
                            WASHINGTON, DC 20555

                                July 5, 1984

Information Notice No. 84-53:   INFORMATION CONCERNING THE USE OF LOCTITE 
                                   242 AND OTHER ANAEROBIC ADHESIVE/SEALANTS

Addressees: 

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

Purpose: 

This information notice is being provided as a notification of a potentially
significant problem pertaining to the use of certain anaerobic 
adhesive/sealants. The NRC staff expects recipients to review this notice 
for applicability to their facilities and consider actions, if appropriate, 
to preclude similar problems from occurring at their facilities. However, 
suggestions contained in this information notice do not constitute NRC 
requirements; therefore, no specific action or written response is required.

Description of Circumstances: 

Philadelphia Electric Company reported that, on November 17, 1983, two 
control rods had exceeded their allowed scram times at Peach Bottom Unit 3. 
An investigation determined the cause of the failure to be a foreign 
substance that bonded the solenoid core plunger to the solenoid base 
assembly of the scram pilot solenoid valve. The foreign material was 
determined to be Loctite 242. Apparently, excess Loctite 242 had not been 
wiped off when it was used on the acorn nut of the solenoid housing. The 
material on the nut had appeared to be a solid and was thought to be cured. 
Upon the return of the system to service, the Loctite 242 that was exposed 
to air liquified and migrated to the position where it eventually caused a 
failure of pilot solenoid valves. 

The NRC is aware of other uses of Loctite in the industry: Loctite 242 at an
operating pressurized water reactor (PWR) on safety injection pump impeller 
locknuts, Loctite 277 at PWRs under construction used as pipe sealant on 
tubing connections to the feed water isolation valve, and Loctite 580 at a 
boiling water reactor under construction in various emergency core cooling 
system valve set screws. No other problems have been identified in these 
other applications. 




8407030085 
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                                                               IN 84-53    
                                                               July 5, 1984 
                                                               Page 2 of 2 

Discussion: 

The Loctite Corporation describes Loctite 242 Threadlocking Adhesive/Sealant
as well as Loctite 580 Nuclear Grade PST (r) Pipe Sealant as thixotropic 
(gels at rest and liquid when agitated) and anaerobic (cures in absence of 
air) compounds. This material does not cure in the presence of air, i.e., 
outside the joint. Loctite 277 Threadlocking Adhesive/Sealant is also 
anaerobic but not thixotropic. Loctite 580 is the substitute product for 242
and 277 for applications in nuclear power plants according to the Loctite 
Corp. 

Technical and maintenance personnel alike are advised to maintain 
familiarity with the most current product data sheets for Loctite and 
similar materials that they use and particularly to utilize nuclear grade 
materials in appropriate applications. Loctite technical information may be 
obtained through Loctite Technical Service Centers in Newington, 
Connecticut, phone (203) 278-1280. 

No written response to this information notice is required. If there are any
questions regarding 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:  M. S. Wegner, IE
                    (301) 492-4511

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