United States Nuclear Regulatory Commission - Protecting People and the Environment

Information Notice No. 85-08: Industry Experience on Certain Materials Used in Safety-related Equipment

                                                             SSINS No. 6835 
                                                             IN 85-08       

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

                              January 30, 1985

Information Notice No. 85-08:   INDUSTRY EXPERIENCE ON CERTAIN MATERIALS 
                                   USED IN SAFETY-RELATED EQUIPMENT 

Addressees: 

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

Purpose: 

This information notice is being issued to provide licensees and 
construction permit holders with information pertaining to the behavior of 
certain materials used in safety-related equipment. The materials, as 
described below, were observed to have the potential of degrading the 
operability of safety-related equipment. These observations were made during 
environmental qualification testing and/or during routine inspection of 
in-service equipment. It is expected that recipients will review the 
information for specific and generic applicability to their facilities. 
However, suggestions contained in this notice do not constitute NRC 
requirements; therefore, no specific action or response is required. 

Description of Circumstances: 

1.   Elastomeric Seals Used in Personnel Air Locks for the Reactor 
     Containment Systems 

     In a recent 10 CFR 21 report to the NRC, the W. J. Woolley Company 
     reported that they have a testing program to qualify one type of 
     airlock that utilizes inflatable elastomeric seals around the perimeter 
     of the door for sealing against differential pressure. During this 
     testing, one of the inflatable seals manufactured by Presray 
     Corporation ruptured. The seal material is an EPDM elastomeric with a 
     fabric reinforcement part way around the seal, and the rupture occurred 
     in the area where the fabric ended. The ruptured seal was subjected to 
     the following conditions during the qualification test: artificial 
     aging for an equivalent of 5 years by exposure to 201F for 200 
     hours, exposure to an integrated radiation dose of 1 x 10-7 rads, and 
     exposure to a test chamber post-LOCA environment of 465F. These 
     parameters are applicable to Midland Nuclear Station. 

     The ruptured seal was examined by Woolley Company and Presray 
     Corporation. It was determined that the high temperature (465F) 
     had weakened the EPDM and caused the material to stretch resulting in a 
     rupture. The W. J. Wooley Company further stated that the Presray 
     inflatable seals may be 

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                                                            IN 85-08        
                                                            January 30, 1985 
                                                            Page 2 of 4     

     inadequate for the following plants because of their relatively high 
     temperature applications: 

          Grand Gulf (Drywell Lock only)          330F 
          Perry (Drywell Lock only)               330F 
          River Bend (Drywell Lock only)          330F 
          South Texas (Containment Locks)         280F

     The Woolley Company is working with Presray Corporation on the design 
     of a new inflatable seal that will have fabric reinforcement around the
     entire seal. The new design will be used to replace the current 
     installed seals, according to the Woolley Company report. 

2.   Epoxy Phenolic Coating Applied to the Lower Portion of the Interior 
     Surface of Diesel Oil Storage Tank 

     In a 10 CFR 50.55(e) report to the NRC, the Philadelphia Electric 
     Company reported that during final inspection of the diesel oil storage
     tanks at Limerick Generating Station, the epoxy phenolic coating on 
     portions of the interior surface of three of the four Unit 1 tanks was 
     observed to have extensive peeling and flaking. If not repaired, these 
     fragments could have entered the fuel oil transfer piping and filters, 
     thus impeding fuel oil flow and potentially causing a diesel generator 
     failure. 

     The specification for Limerick Station required that the entire 
     interior surface of the tanks be coated with an inorganic zinc primer 
     to a thickness of between 2.0 mils and 4.0 mils. On top of the zinc 
     primer, an epoxy phenolic coating was applied to a minimum of 12 mils 
     and a maximum of 18 mils dry film thickness. 

     Philadelphia Electric Company stated that there are two factors that 
     may have contributed to the coating failure: (1) chemical 
     incompatibility between the zinc primer and the epoxy coating, and (2) 
     improper curing of the zinc primer. 

     Subsequent investigation by Philadelphia Electric Company has revealed 
     an additional concern regarding the coating system. The zinc in the 
     primer coat may react adversely with diesel fuel when exposed over a 
     long period of time. Products of this reaction are often soluble when 
     the fuel is at room temperature, but may degrade into insoluble gums as
     the fuel passes through the hot injectors and intake manifolds of a 
     diesel engine, and thus may result in degraded performance as the 
     engine is operated over a period of time. 

     The Philadelphia Electric Company has proposed corrective actions to 
     provide sufficient protection against the deficiencies described above 
     and also against any internal corrosion of the tanks as a result of 
     internal condensation. The interior surface of the tanks will be 
     sandblasted to white metal and recoated with a substitute epoxy 
     phenolic coating applied directly to the white metal. The new coating 
     will be certified by the vendor for compatibility with diesel fuel.
.

                                                            IN 85-08        
                                                            January 30, 1985
                                                            Page 3 of 4     

3.   The Use of Viton Elastomer as the Seal Material in Hydrogen Recombiner 
     Applications 

     In a 10 CFR 21 report, Rockwell International reported that during the 
     evaluation of the post-LOCA hydrogen recombiner to develop methodology 
     for mechanical qualification of pressure retaining components, a 
     concern was raised as to the appropriateness of the use of Viton 
     elastomer as the seal material in recombiner application. Initial 
     findings indicate that Viton material would compress as a result of 
     exposure to radiation, elevated temperature, and steam. This 
     compression may cause some loss of sealing capability when the 
     temperature is subsequently reduced. Literature searches and inquiries 
     to vendors and research organizations reveals that, in laboratory 
     tests, Viton will exhibit deterioration in seal effectiveness when 
     exposed to environmental parameters similar to those conditions for 
     which the RI recombiners are designed. The effects on Viton elastomer 
     are believed to be synergistic, but the extent of synergism is not 
     quantifiable; e.g., steam absorption softens the material while 
     radiation and temperature harden it. 

     Rockwell International has recommended that its customers replace Viton
     seals with alternate seals. 

4.   Environmental Qualification of ASCO NP Valves With Viton and Ethylene 
     Propylene Parts 

     The Equipment Qualification Branch of the Office of Nuclear Reactor 
     Regulation has reached the conclusions listed below regarding the 
     qualification of ASCO NP Solenoid Valves. This information superceeds 
     and/or supplements information previously provided in IE Information 
     Notices 80-11, 81-29 (Equipment Environmental Qualification Notice No. 
     10--Test Summary Report No. 1) and 82-52 (Equipment Environmental 
     Qualification Notice 10--Test Summary Report No. 2). 

     a.   ASCO NP series solenoid valves with resilient seats and Viton 
          elastomers may be considered qualified only for those applications
          in which the valves are not required to shift position following 
          exposure to total gamma radiation doses greater than 20 megarads 
          up to 200 megarads. No qualification data are available for 
          applications in which the radiation dose exceeds 200 megarads 
          gamma. 

     b.   Except for model NP 8316 with Ethylene Propylene elastomers 
          (Suffix "E"), ASCO NP series solenoid valves are considered 
          qualified to the extent and levels reported in Table 5.1, pages 59 
          and 60 of ASCO Test Report No. AOR-78368/Rev. 1, "Report on 
          Qualification of Automatic Switch Co. (ASCO) Category NP-1 
          Solenoid Valves for Safety-Related Applications in Nuclear Power 
          Generating Stations," dated March 2, 1982. 

     c.   ASCO valve model NP 8316 with Ethylene Propylene elastomers is 
          considered qualified to the levels reported in Isomedix Test 
          Report No. AOS 21678/TR, Rev. A, dated March 1978, revised July 
          1979. (Category III as defined in Table 5.1 of ASCO Test Report 
          AOR-67368/Rev. 1.)
.

                                                            IN 85-08        
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Discussion: 

The above described circumstances, along with those circumstances that were 
described and disseminated previously in Information Notices 84-12, 84-31, 
and 84-83 point out the need for ongoing surveillance and evaluation of 
in-service equipment to detect material degradation that may occur as a 
result of the synergistic effects between material in use and the normal 
operating requirements and associated environmental parameters. 

The operability of the equipment will be less reliable as its constituent 
materials age. The actual degradation of equipment is not quantifiable 
because the synergistic effect of material is dependent on (1) the 
environmental parameters where the equipment is installed and (2) the cyclic
and functional design requirements of the equipment. Very often, records of 
these environmental parameters (under normal and abnormal conditions) and 
records of equipment cycling or operation are not readily available and have
not been accounted for during the environmental qualification review 
process. Therefore, a routine surveillance program for equipment that is 
known to contain degradable material might be considered. Some licensees 
have indicated that they are considering such a program, including periodic 
review of the resulting data. 

The items described in the above description of circumstances identify 
certain deficiencies in specific equipment types. However, the NRC staff 
considers that the potential effect of each of the above deficiencies is 
generic in nature and is applicable to other equipment where circumstances 
are similar. 

No specific action or written response is required by this notice. If you 
have any questions concerning this notice, 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:  U. Potapovs, IE
                    (301) 492-8030

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