Information Notice 1988-06, Foreign Objects in Steam Generators
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UNITED STATES
NUCLEAR REGULATORY COMMISSION
OFFICE OF NUCLEAR REACTOR REGULATION
WASHINGTON, D.C. 20555
February 29, 1988
FOREIGN OBJECTS IN STEAM GENERATORS
Addressees
All holders of operating licenses or construction permits for pressurized
water reactors (PWRs).
Purpose
This information notice is being provided to alert addressees to a potentially
generic problem with foreign objects on the secondary side of steam generators
in PWRs and the potential for failure of steam generator tubes as a result of
fretting.
It is expected that recipients will review the information for ap- plicability to their facilities and consider actions, as appropriate, to pre- clude similar problems from occurring at their facilities. However, suggestions
contained in this information notice do not constitute NRC requirements; there- fore, no specific action or written response is required.
Description of Circumstances
On February 3, 1988, during the first refueling outage at Catawba 2, the licensee
submitted a report to the NRC, as required under 10 CFR 50.72, indicating that
foreign metal objects in two of four steam generators had caused loss of 50% of
the wall thickness for one tube in each of these steam generators. One of the
objects was a steel block 1-1/2 inches x 2 inches x 3 inches and the other was
a steel sliver approximately 1/4 inch x 3/8 inch x 8 inches. Both objects were
located on the tube sheet.
On the basis of a subsequent evaluation, the licensee
concluded that it was unlikely that these obJects had caused damage.
However, the licensee found three jacking studs 2 to 3 inches long by 2-1/4 inches in
diameter on the tube sheet in one of the other two steam generators. One of
these studs did cause significant damage to a tube in that steam generator.
The licensee also found small gauge wire, a nail, a 6 inch piece of welding
rod, and welding slag in the steam generators. The licensee was able to remove.
all of the foreign objects and debris except for the piece of welding rod.
The
licensee did eddy current testing of 100% of the peripheral tubes in all of the
steam generators for Catawba 2 and found that plugging of seven tubes was neces- sary. Of the seven tubes plugged, two had visible damage to the exterior surface
near the tube sheet. The maximum defect indicated by eddy current testing was 77%.
The licensee's records indicate that all of the steam generators were carefully
inspected for foreign objects after fabrication of the steam generators was com- pleted and prior to operation of the reactor at power.
Nothing of significance
IN 88-06 February 29, 1988 was found at that time. The foreign objects and debris found recently in the
steam generators may have accumulated in the top works of the steam generators
and may have been washed down to the tube sheet after preservice inspections.
Discussion:
As described in NUREG/CR-0718, 'Steam Generator Tube Integrity Program Phase I
Report," tests for certain steam generators Indicate that tube failure can be
expected during normal operation if the tube wall thickness is reduced by 85%
to 90% and if the defect is 1-inch long or longer. Likewise, during a steam
line break accident, failure can be expected if wall thickness is reduced by
75% to 80%.
Information Notice 83-24, "Loose Parts in the Secondary Side of Steam Generators
at Pressurized Water Reactors," addressed events involving foreign objects and
loose parts on the secondary side of steam generators at PWRs, including the
events at Ginna and Prairie Island I where tube ruptures were related to the
presence of loose parts.
Generic Letter 85-02, "Staff Recommended Actions Stemming from NRC Integrated
Program for Resolution of Unresolved Safety Issues Regarding Steam Generator
Tube Integrity," requested that PWR licensees perform visual inspections on
steam generator secondary sides in the vicinity of the tube sheet along the
entire periphery of the tube bundle and the tube lane to identify any foreign
objects-and-damage-to-the external surfaces of tubes. For licensees with
operating licenses, these inspections were to be performae durIng the next--
planned outage for eddy current testing and after any secondary side repairs
or modifications to steam generator internals were completed.
For applicants
for operating licenses, these inspections were to be performed as part of the
preservice Inspection program. The licensee for Catawba 2 complied with this
request as an applicant for an operating license. The preservice inspections
would not detect foreign objects in the top works of the steam generators that
could be washed down to the tube sheets during the first fuel cycle.
No specific action or written response is required by this information notice.
If you have questions about this matter, please contact the technical contact
listed below or the Regional Administrator of the appropriate regional office.
Charles E. Rossi, Director
Division of Operational Events Assessment
Office of Nuclear Reactor Regulation
Technical Contact:
Roger Woodruff, NRR
(301) 492-1180
Attachment: List of Recently Issued NRC Information Notices
Attachment
February 29, 1988
Page I of i
LIST OF RECENTLY ISSUED
NRC INFORMATION NOTICES
Information
Date of
Notice No.
Subject
Issuance
Issued to
88-05
88-04
88-03
88-02
Fire in Annunciator Control
Cabinets
Inadequate Qualification
and Documentation of Fire
Barrier Penetration Seals
Cracks in Shroud Support
Access Hole Cover Welds
2/11/88
'2/5/88
2/2/88
2/2/88
All holders of OLs
or CPs for nuclear
power reactors.
All holders of OLs
or CPs for nuclear
power reactors.
All holders of OLs
All NRC licensees
authorized to possess
gauges under a
specific or general
license.
88-01
SafetyInjection Pipe
- ~~Fa
iT-Ore
-'
1/27/88
--All holders of OLs
or CPs for nuclear
power reactors.
86-81, Supp. 1
87-67
87-66
87-28, Supp. 1
87-65
Broken External Closure
Springs on Atwood & Morrill
Main Steam Isolation Valves
Lessons Learned from
Regional Inspections of
Licensee Actions in Response
Inappropriate Application
of Commercial-Grade
Components
Air Systems Problems at
U.S. Light Water Reactors
Plant Operation Beyond
Analyzed Conditions
1/11/88
12/31/87
12/31/87
12/28/87
12/23/87
All holders of OLs
or CPs for nuclear
power reactors.
All holders of OLs
or CPs for nuclear
power reactors.
All holders of OLs
or CPs for nuclear
power reactors.
All holders of OLs
or CPs for nuclear
power reactors.
All holders of OLs
or CPs for nuclear
power reactors.
OL = Operating License
CP F Construction Permit
-
IN 88-06 February 29, 1988 was found at that time. The foreign objects and debris found recently in the
steam generators may have accumulated in the top works of the steam generators
and may have been washed down to the tube sheet after preservice inspections.
Discussion:
As described in NUREG/CR-0718, "Steam Generator Tube Integrity Program Phase I
Report," tests for certain steam generators indicate that tube failure can be
expected during normal operation if the tube wall thickness is reduced by 85%
to 90% and if the defect is 1-inch long or longer.
Likewise, during a steam
line break accident, failure can be expected if wall thickness is reduced by
75% to 80%.
Information Notice 83-24, 'Loose Parts in the Secondary Side of Steam Generators
at Pressurized Water Reactors," addressed events involving foreign objects and
loose parts on the secondary side of steam generators at PWRs, including the
events at Ginna and Prairie Island 1 where tube ruptures were related to the
presence of loose parts.
Generic Letter 85-02, "Staff Recommended Actions Stemming from NRC Integrated
Program for Resolution of Unresolved Safety Issues Regarding Steam Generator
Tube Integrity," requested that PWR licensees perform visual inspections on
steam generator secondary sides in the vicinity of the tube sheet along the
entire periphery of the tube bundle and the tube lane to identify any foreign
objects and damage to the external surfaces of tubes.
For licensees with
operating licenses, these inspections were to be performed during the next
planned outage for eddy current testing and after any secondary side repairs
or modifications to steam generator internals were completed.
For applicants
for operating licenses, these inspections were to be performed as part of the
preservice inspection program. The licensee for Catawba 2 complied with this
request as an applicant for an operating license. The preservice inspections
would not detect foreign objects in the top works of the steam generators that
could be washed down to the tube sheets during the first fuel cycle.
No specific action or written response is required by this information notice.
If you have questions about this matter, please contact the technical contact
listed below or the Regional Administrator of the appropriate regional office.
Charles E. Rossi, Director
Division of Operational Events Assessment
Office of Nuclear Reactor Regulation
Technical Contact:
Roger Woodruff, NRR
(301) 492-1180
Attachment: List of Recently Issued NRC Information Notices
- see previous concurrence
EAB:NRR*
EAB:NRR*
C:EAB:NRR*
C:GCB:NRR* Tech Ed* AD:RGN II*
RWoodruff:db RLobel
Wianning
CBerlinger AThomas
GLainas
2/18/88
2/19/88
2/19/88
2/22/88
2/18/88
2/19/88
IN 88- February xx, 1988 was found at that time. The foreign objects and debris found recently in the
steam generators may have accumulated in the top works of the steam generators
and may have been washed down to the tube sheet after preservice inspections.
Discussion:
As described in NUREG/CR-0718, "Steam Generator Tube Integrity Program Phase I
Report," tests for certain steam generators indicate that tube failure can be ex- pected during normal operation if the tube wall thickness is reduced by 85% to 90%
and If the defect is 1-inch long or longer. Likewise, during a steam line break
accident, failure can be expected if wall thickness is reduced by 75% to 80%.
Information Notice 83-24, "Loose Parts in the Secondary Side of Steam Generators
at Pressurized Water Reactors," addressed events involving foreign objects and
loose parts on the secondary side of steam generators at PWRs, including the
events at Ginna and Prairie Island 1 where tube ruptures were related to the
presence of loose parts.
Generic Letter 85-02, "Staff Recommended Actions Stemming from NRC Integrated
Program for Resolution of Unresolved Safety Issues Regarding Steam Generator
Tube Integrity," requested that PWR licensees perform visual inspections on
steam generator secondary sides in the vicinity of the tube sheet along the
entire periphery of the tube bundle and the tube lane to identify any foreign
objects and damage to the external surfaces of tubes.
For licensees with
operating licenses, these inspections were to be performed during the next
planned outage for eddy current testing and after any secondary side repairs
or modifications to steam generator internals were completed. For applicants
for operating licenses, these inspections were to be performed as part of the
preservice inspection program. The licensee for Catawba 2 complied with this
request as an applicant for an operating license.
On the basis of the assumption that foreign objects had been in the top works
of the Catawba 2 steam generators and that these objects could have been washed
down to the tube sheets after the preservice inspection, the licensee performed
after the first fuel cycle an additional visual inspection on the secondary side
of each steam generator in the vicinity of the tube sheet, found the foreign
objects and debris, and removed them before they could cause failure of a tube.
No specific action or written response is required by this information notice.
If you have questions about this matter, please contact the technical contact
listed below or the Regional Administrator of the appropriate regional office.
Charles E. Rossi, Director
Division of Operational Events Assessment
Office of Nuclear Reactor Regulation
Technical Contact:
Roger Woodruff, NRR
(301) 492-1180
D:DOEA
CERossi
Attachment: List of Recently Issued NRC Informat on Notices
2/ /88
- see previous concurrence C
C&
'
EAB:NRR*
EAB:NRR*
C:EAB:NRR*
C:GCB:NRf Tech Ed* AD:RGN II*
RWoodruff:db RLobel
WLanning
CRerlinger AThomas
GLainas
2/18/88
2/19/88
2/19/88
2/1, /88
2/18/88
2/19/88
works of the steam generators and may have been washed down to the tube sheet
after preservice inspections.
Discussion:
As described in NUREG/CR-0718, tests for certain steam generators indicate
that tube failure can be expected during normal operation if the tube wall
thickness is reduced by 85% to 90% and if the defect is 1-inch long or
longer. Likewise, during a steam line break accident, failure can be
expected if wall thickness is reduced by 75% to 80%.
Information Notice 83-24 addressed events involving foreign objects and loose
parts on the secondary side of steam generators at PWRs, including the events
at Ginna and Prairie Island 1 where tube ruptures were related to the
presence of loose parts.
Generic Letter 85-02 requested that PWR licensees perform visual inspections
on steam generator secondary sides in the vicinity of the tube sheet along
the entire periphery of the tube bundle and the tube lane to identify any
foreign objects and damage to the external surfaces of tubes.
For licensees
with operating licenses, these inspections were to be performed during the
next planned outage for eddy current testing and after any secondary side
repairs or modifications to steam generator internals were completed.
For
applicants for operating licenses, these inspections were to be performed as
part of the preservice inspection program.
The licensee for Catawba 2
complied with this request as an applicant for an operating license.
On the basis of the assumption that the foreign objects and debris in the
Catawba 2 steam generators had been in the top works of the steam generators
and were washed down to the tube sheet, an additional careful visual
inspection on the secondary side of each steam generator in the vicinity of
the tube sheet along the entire periphery of the tube bundle and the tube
lane is suggested as a way to preclude similar problems at newer plants. In
addition to the preservice inspection, it is suggested that these inspections
be performed after initial operation and before startup after the first
refueling outage.
No specific action or written response is required by this information
notice. If you have questions about this matter, please contact the
technical contact listed below or the Regional Administrator of the
appropriate regional office.
Charles E. Rossi, Director
Division of Operational Events Assessment
Office of Nuclear Reactor Regulation
Technical Contacts: Roger Woodruff, NRR
(301) 492-1180
Attachment:
Lis of Recently Issued Information Noti s
CONCURRENCE: Woodr1ff, L
, L
Berlinger, T d Ed, L
s, Rossi
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