Protecting People and the EnvironmentUNITED STATES NUCLEAR REGULATORY COMMISSION
UNITED STATES
NUCLEAR REGULATORY COMMISSION
OFFICE OF NUCLEAR REACTOR REGULATION
WASHINGTON, DC 20555-0001
March 24, 1997
NRC INFORMATION NOTICE 97-13: DEFICIENT CONDITIONS ASSOCIATED WITH
PROTECTIVE COATINGS AT NUCLEAR POWER
PLANTS
Addressees
All holders of operating licenses or construction permits for nuclear power
reactors.
Purpose
The U.S. Nuclear Regulatory Commission (NRC) is issuing this information
notice to alert addressees about several instances in which protective
coatings have not been properly applied, maintained, or qualified for their
intended use and have jeopardized the operability of safety-related equipment.
It is expected that recipients will review this information for applicability
to their facilities and consider actions, as appropriate, to avoid similar
problems. However, suggestions contained in this information notice are not
NRC requirements; therefore, no specific action or written response is
required.
Background
Protective coatings are used in many applications at nuclear power plants.
For example, coatings may be used to protect the inside surfaces of storage
tanks and containment liners from corrosion, to protect the inside surfaces of
piping systems from erosion and corrosion, or to seal exposed concrete
surfaces. Additionally, coatings may be applied to provide a skid-resistant
surface to walk on or to control contamination.
Description of Circumstances
Several instances have been reported to the NRC recently in which protective
coatings have either not been properly applied and maintained or have not been
adequately qualified for their intended use. The following are examples:
1. Pipe Coating Material Found in the A-Train Recirculation Spray Heat
Exchangers at Millstone Unit 3
On July 25, 1996, Northeast Nuclear Energy Company reported in Licensee
Event Report (LER) 96-025 (Accession Number 9608270262) that about 20
pieces of Arcor were found in the "A" train recirculation spray heat
exchangers at Millstone Unit 3. Arcor is a coating material that was
applied to the inside surfaces of the service water system piping at
Millstone Unit 3. The licensee stated that Arcor chips were swept
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into the recirculation spray heat exchanger channel heads during
engineered safety features/loss of power testing that had been
conducted. The licensee also found 40 to 50 mussel shell fragments in
the heat exchangers. Although the Arcor chips and mussel fragments were
relatively small (on the order of 1 inch by 1 inch), the licensee
determined that the number and size of Arcor chips and mussel fragments
could have prevented the "A" train recirculation spray heat exchangers
from performing their specified safety function.
The licensee determined that the Arcor chips were from a second coat of
Arcor that was applied in the field (as opposed to being applied in the
shop) to the internal diameter of the "A" train service water system
piping. The licensee concluded that the plant's procedures for field
application of the Arcor coating were not adequate to ensure proper
bonding of the second coat. As corrective actions, the licensee planned
to revise the procedure for the application of the Arcor to more
adequately ensure proper bonding between the first and second coatings,
and to visually inspect the "A" train service water system to determine
the location and extent of Arcor delamination. Repairs to any affected
areas of the "A" train service water system piping would use the revised
procedure for Arcor application. A flushing and inspection of the "B"
train recirculation spray heat exchangers did not disclose additional
Arcor chips or mussel fragments.
2. Degradation of Protective Coatings Used Inside Containment
Zion Unit 2
In November 1996, Commonwealth Edison Company found that 40 percent to
50 percent of the concrete floor coatings at Zion Unit 2 showed
extensive failure as a result of mechanical damage and wear and that
about 5 percent of the coating associated with the concrete wall and
liner plate was degraded. Although adhesion tests showed acceptable
adhesion strength in most of the locations tested, one test that was
made on an unqualified coating system did not satisfy the acceptance
criteria. Unqualified coatings had been applied to various surfaces,
including instrument racks, struts, charcoal filter housings, valve
bodies, and piping. Also, documentation was not found for overcoating
(i.e., touch-up work) that had been applied to many of the liner plates
and concrete wall surfaces.
To resolve the coating discrepancies that were identified in the Zion
Unit 2 containment, all of the loosely adherent coatings were removed
and material transport calculations were performed for the coated
surfaces inside containment. These calculations were used to define a
"zone of influence" relative to the containment sump, and the licensee
has removed all of the unqualified coatings that existed within this
zone, except for small amounts that might be present on items such as
identification tags, signs, and lighting fixtures. The licensee
estimated that about 110m2 [1200 ft2] of unqualified coatings existed in
the Unit 2 containment. In addition .
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to these immediate actions, the licensee was establishing a long-term
corrective action plan and a coating maintenance program to fully
resolve the coating discrepancies at the Zion station.
Indian Point Unit 2
On March 10, 1995, the Consolidated Edison Company reported in LER 95-
005 (Accession Number 9503210115) that paint was peeling from a floor in
the Indian Point Unit 2 containment. The licensee found that the
following factors contributed to the delamination of the paint: (1) the
paint thickness exceeded the manufacturer's specifications by up to
twice the allowed thickness; (2) there was excessive paint shrinkage
caused by using too much paint thinner; (3) the surface had not been
properly cleaned and prepared before the paint was applied; and (4)
inspection and documentation requirements conforming to American
National Standards Institute (ANSI) N101.4, "Quality Assurance for
Protective Coatings Applied to Nuclear Facilities," which was invoked by
the existing specification for the activity, were not implemented. The
licensee concluded that the root cause of the observed condition
resulted from the failure of personnel to follow approved procedures for
painting applications.
Sequoyah Units 1 and 2
On October 18, 1993, the Tennessee Valley Authority reported in LER 93-
026 (Accession Number 9310260116) that unidentified coatings were used
on the exterior surfaces of reactor coolant pump motor support
structures at Sequoyah Units 1 and 2. These support structures are
located completely within the containment sump "zone of influence" at
both of the Sequoyah units. The surface area of unqualified coating
found on each of these support structures involved about 13m2 [143 ft2]
of material, whereas the maximum amount of uncontrolled coatings allowed
to exist in the zone of influence at the Sequoyah units without
affecting the operability of the emergency core cooling and spray
systems was set at 5m2 [56.5 ft2]. As corrective action, the licensee
modified the motor support structures to include "catch" screens to
prevent coatings on the motor support structures from reaching the
strainers in the containment sumps.
Discussion
The failure of coatings to adhere to exposed surfaces inside containment and
to the internal surfaces of fluid systems can result in clogged strainers,
filters, and nozzles and can compromise the ability of safety-related
equipment to function (e.g., the service water system, the containment spray
system, and the emergency core cooling systems). It is important that coating
systems remain adherent and intact during normal operating and transient
conditions, as well as during the most extreme environmental conditions that
can exist during design-basis accident conditions, especially if coating
system failure can jeopardize the operability of safety-related equipment.
Industry standards provide certification and qualification requirements for
coatings that are used in these applications. Additionally, industry
standards for coatings as well as vendor instructions and recommendations
provide guidance pertaining .
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to such things as surface preparation and cleanliness requirements,
temperature control, humidity control, timing requirements for multiple coat
applications, application methods, and personnel qualification and training
requirements. Depending on the specific application, a combination of in situ
testing and periodic inspection of coatings may be necessary to ensure that
the coating has been adequately applied and remains intact over time.
Coating activities that can affect safety-related equipment are governed in
general by Title 10 of the Code of Federal Regulations, Part 50, Appendix B,
"Quality Assurance Criteria for Nuclear Power Plants and Fuel Reprocessing
Plants." Criterion IX of Appendix B, "Control of Special Processes," is
especially relevant and requires that "Measures shall be established to assure
that special processes...are controlled and accomplished by qualified
personnel using qualified procedures in accordance with applicable codes,
standards, specifications, criteria, and other special requirements."
Regulatory Guide 1.54, "Quality Assurance Requirements for Protective Coatings
Applied to Water-Cooled Nuclear Power Plants," provides guidance on a way to
comply with these quality assurance requirements as they relate to protective
coating systems that are applied to ferritic steel, aluminum, stainless steel,
zinc-coated (galvanized) steel, and masonry surfaces.
This information notice requires no specific action or written response. If
you have any questions about the information in this notice, please contact
one of the technical contacts listed below or the appropriate Office of
Nuclear Reactor Regulation (NRR) project manager.
signed by M.M. Slosson
Thomas T. Martin, Director
Division of Reactor Program Management
Office of Nuclear Reactor Regulation
Technical contacts: James Medoff, NRR
(301) 415-2715
E-mail: jxm@nrc.gov
James Tatum, NRR
(301) 415-2805
E-mail: jet1@nrc.gov
