Information Notice 1985-08, 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
IE 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 2010F for 200 hours0.00231 days <br />0.0556 hours <br />3.306878e-4 weeks <br />7.61e-5 months <br />, exposure to an integrated radiation dose
of 1 x 107 rads, and exposure to a test chamber post-LOCA environment
of 4650F. 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 (4650F) 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
8501290041
IN 85-08 January 30, 1985 inadequate for the following plants because of their relatively high
temperature applications:
Grand Gulf (Drywell Lock only)
3300F
Perry (Drywell Lock only)
3300F
River Bend (Drywell Lock only)
3300F
South Texas (Containment Locks)
2800F
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 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 qualfication data are available for appli- cations 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 qualfied 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 January 30,. 1985 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.
Ytkar
rect or
Divisic of Emergency Preparedness and
Engineering Response
Office of Inspection and Enforcement
Technical Contact:
U. Potapovs, IE
(301) 492-8030
Attachment:
List of Recently Issued IE Information Notices
Attachment
January 30, 1985
LIST OF RECENTLY ISSUED
IE INFORMATION NOTICES
Information
Date of
Notice No.
Subject
Issue
Issued to
85-07
85-06
Contaminated Radiography
Source Shipments
Contamination of Breathing
Air Systems
Pipe Whip Restraints
Inadequate Management Of
Security Response Drills
1/29/85
1/23/85
1/23/85
1/17/85
85-05
85-04
85-03
85-02 Separation Of Primary Reactor 1/15/85
Coolant Pump Shaft And
Impeller
All NRC licensees
authorized to
possess industrial
radiography sources
All power reactor
facilities holding
All power reactor
facilities holding
All power reactor
facilities holding
fabrication & pro- cessing facilities
All pressurized water
power reactor
facilities holding an
All power reactor
facilities holding
All material licensees
possessing irradiators
that are not self- shielded and contain
more than 10,000
curies of radioactive
material
All NRC materials
licensees other than
licensees that use
sealed sources only
85-01
Improper Installation And
Testing Of Differential
Pressure Transmitters
Continuous Supervision Of
Irradiators
Reconcentration Of Radio- nuclides Involving Discharges
Into Sanitary Sewage Systems
Permitted Under 10 CFR 20.303
1/15/85
1/10/85
12/21/84
84-94 OL = Operating License
CP = Construction Permit