Information Notice 1987-36, Significant Unexpected Erosion of Feedwater Lines
SSINS No.:
6835 IN 87-36
UNITED STATES
NUCLEAR REGULATORY COMMISSION
OFFICE OF NUCLEAR REACTOR REGULATION
WASHINGTON, DC 20555
August 4, 1987
NRC INFORMATION NOTICE NO. 87-36: SIGNIFICANT UNEXPECTED EROSION OF
FEEDVATER LINES
Addressees
All nuclear power reactor facilities holding an operating license or a con- struction permit.
Purpose
This information notice is provided to alert recipients to a potentially
generic problem pertaining to significant unexpected erosion which resulted
in pipe wall thinning in the safety-related portions of feedwater lines and
other related problems. It is expected that recipients will review the Infor- mation for applicability to their facilities and consider actions, if appro- priate, to preclude a similar problem. However, suggestions contained in this
notice do not constitute NRC redpuirements; therefore no specific action or
written response is required.
Description of Circumstances
At the Trojan Nuclear Plant it was discovered that at least two areas of the
straight sections of the main feedwater piping system experienced wall thinning
to an extent that the pipe wall thickness would have reached the minimum thick- ness required by the design code (ANSI B31.7, "Nuclear Power Piping") during
the next refueling cycle. These areas are in safety-related portions of ASME
Boiler and Pressure Vessel Code (ASME Code) Class 2 piping inside containment.
The pipe wall had thinned in both horizontal and vertical runs that were at
least seven pipe diameters downstream of elbows or other devices that can cause
flow turbulence. Criteria developed by the Electric Power Research Institute
(EPRI Users Manual NSAC-112, "CHEC [Chexal-Horowitz-Erosion-CorrosionJ,I dated
June 1987) would not have required that the pipe wall in these straight sec- tions be examined.
Although the straight sections of eroded 14-inch pipe were slightly thicker
than the minimum required thickness, it was projected that the pipe wall
thickness would erode below the minimum required thickness before the next
major outage. Consequently, the licensee plans to replace this piping before
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IN 87-36 August 4, 1987 The Trojan plant is conducting a failure analysis on the degraded components to
determine the causes and mechanisms involved in the observed wall thinning
event. The NRC is evaluating the data available to determine any generic
implication of the event.
Related Generic Communications:
IE Information Notice 82-22, "Failure in Turbine Exhaust Lines," dated July 9,
1982 provides additional information pertaining to erosion/corrosion in wet
steam piping. Other erosion/corrosion events pertaining specifically to the
feedwater systems (including emergency and auxiliary feedwater) have occurred
in feedwater pump minimum-flow lines, J-tubes in steam generator feedwater
rings, and emergency feedwater supply to a helium circulator.
IE Information Notice 86-106, "Feedwater Line Break," was issued December 16,
1986. It described the then-known details of the December 9,, 1986 failure of
the suction line to a main feedwater pump at Surry Power Station Unit 2.
Supplement 1 to this information notice, which was issued February 13, 1987, provided additional detail on the failure mechanism. Supplement 2, which was
issued on March 10, 1987, discussed the effects of the system interactions that
resulted from the line break.
NRC Bulletin 87-01, "Thinning of Pipe Wall in Nuclear Power Plants," issued on
Juty-9;-987, requested that iTcensees submit information concernffng-thirlf
programs for monitoring the thickness of pipe walls in high-energy single-phase
and two-phase carbon steel piping systems.
No specific action or written response is required by this information notice.
If you have any questions about this matter, please contact the Regional
Administrator of the appropriate NRC regional office or this office.
rle
E.RostDirector
Division of Operational Events Assessment
Office of Nuclear Reactor Regulation
Technical Contact:
Paul C. Wu, NRR
(301) 492-8987 Attachment: List of Recently Issued NPC Information Notices
IN 87-36 August 4, 1987 The licensee believes that the high flow velocity of 22.6 ft/sec, in combina- tion with other operating factors, may be the cause of the thinning.
This thinning was discovered when the steam piping inspection program at the
Trojan plant was expanded to include single-phase piping. Trojan personnel
inspected essentially all safety-related high energy carbon steel piping
inside containment.
In addition, the licensee discovered approximately 30 additional areas of the
main feedwater piping system where the pipe wall had thinned so the thickness
of the pipe wall was either less than the minimum thickness required by the
design code or would have eroded to the minimum required thickness during the
next operating cycle. Of these areas, 10 were in the safety-related portions
of the system, while the rest were in non-safety-related portions. All of
these thirty additional areas were in regions that the EPRI criteria would have
indicated as 'needing examination.
Discussion:
The feedwater system inside containment consists of four lines.
are mirror images, as are Lines C and D. The parameters of the
2 portion of the piping system are as listed below.
Lines A and B
ASME Code Class
Design Temperature
^
Operating Temperature
Design Pressure
Operating Pressure
Piping Material
Diameter
Wall Thickness Nominal
Wall Thickness Minimal (ANSI B31.7)
Oxygen Content
pH
Flow Velocity
4450F
4450F
1125 psi
920 psi
A-106 GRB
14-in. OD
0.593 in.
0.510 in.
4 ppb
9.0
22.6 ft/sec @ 100% power
The thinning of the straight sections occurred in Lines A and D.
A number of 45- and 90-degree elbows and
The thickness of the remaining pipe wall
0.46 in. The minimum required thickness
ness at time of installation was 0.593 ir
two 60-degree elbows were also replaced.
in these areas ranged from 0.43 to
is 0.499 in., and nominal wall thick- In the non-safety-related portions of the feedwater lines, a total of 20 pieces
of 14-in. pipe were replaced. This total included elbows as well as some
straight pieces down stream of the elbows or other discontinuities. The
thinning in these segments is very similar to that in the ASME Code Class 2 portion except that the minimum required thickness was 0.44 in.
Trojan personnel also replaced a segment of 30-in. header pipe after identify- ing a localized portion of header pipe that had eroded to 1.018-in. wall.
thickness (a minimum thickness of 1.63 in. was required).
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Attachment
August 4, 1987
LIST OF RECENTLY ISSUED
INFORMATION NOTICES 1987
InTornation
Notice No.
87-35
87-34
87-33
87-3?
87-31
87-30
87-29
87-28 Dare or
Subject
Issuance
Reactor Trip Breaker,
7/30/87 Westinghouse Model DS-416,
Failed to Open on Manual
Initiation from the Cortrol
PooP
Single Failures in AuxIliary 7/24/87
Feedwater Systems
Applicability of 10 CFR
Part 21 to Nonlicensees
Deficiencies In the Testing
of Nuclear-Grade kctivated
Charcoal.
8locking. Bracing, and
Securing of Radioactive
Materials Packages in
Transportation.
Cracking of Surge Ring
Brackets in Large General
Electric Company Electric
Motors.
Recent Safety-Related
Incidents at Larqe
Irradiators.
Air Systems Problems at
U.S. Light Water Reactors.
7/24/87
7/10/87
7/10/87
7/2/87 Issued to
All nuclear power
reactor facilities
holding an OL or
CP employing W DS-J'6 reactor trip 6reakers.
All holders of an
pressurized water
reactor facilities.
All NRC licensees.
All nuclear power
reactor facilities
All NRC licensees.
All nuclear power
reactor facilities
6/26/87
All NRC licensees
authorized to possess
and use sealed sources
in large irradiators.
6/27/87
All nuclear power
reactor facilities
OL u Operating License
- Construction Permit
UNITED STATES
NUCLEAR REGULATORY COMMISSION
WASHINGTON, D.C. 20555
OFFICIAL BUSINESS
PENALTY FOR PRIVATE USE, $300
FlRST CLASS MAIL
POSTAGE
- FEES PAID
WASH. D.C.
PERMIT No.
a4j
IN 87-36 August 4, 1987 The Trojan plant is conducting a failure analysis on the degraded components to
determine the causes and mechanisms involved in the observed wall thinning
event. The NRC is evaluating the data available to determine any generic
implication of the event.
Related Generic Communications:
IE Information Notice 82-22, "Failure in Turbine Exhaust Lines," dated July 9,
1982 provides additional information pertaining to erosion/corrosion in wet
steam piping. Other erosion/corrosion events pertaining specifically to the
feedwater systems (including emergency and auxiliary feedwater) have occurred
in feedwater pump minimum-flow lines, J-tubes in steam generator feedwater
rings, and emergency feedwater supply to a helium circulator.
FE Info mation Notice 86-106, "Feedwater Line Break," was issued December 16,
1986. It described the then-known details of the December 9, 1986 failure of
the suction line to a main feedwater pump at Surry Power Station Unit 2.
Supplement 1 to this information notice, which was issued February 13, 1987, provided additional detail on the failure mechanism. Supplement 2, which was
issued on March 10, 1987, discussed the effects of the system interactions that
resulted from the line break.
NRC Bulletin 87-01, "Thinning of Pipe Wall in Nuclear Power Plants," issued on
July 9, 1987, requested that licensees submit information concerning their
programs for monitoring the thickness of pipe walls in high-energy single-phase
and two-phase carbon steel piping systems.
No specific action or written response is required by this information notice.
If you have any questions about this matter, please contact the Regional
Administrator of the appropriate NRC regional office or this office.
Charles E. Rossi, Director
Division of Operational Events Assessment
Office of Nuclear Reactor Regulation
Technical Contact:
Paul C. Wu, NRR
(301) 492-8987 Attachment: List of Recently Issued NRC Information Notices
- SEE PREVIOUS CONCURRENCES
- C/OGCB:DOEA:NRR
- PPMB:ARM
CHBerlinger
TechEd
07p4 87
07/28/87
07/28/87
- OGCB.DOEA:NRR
- ECE :DEST:NRR
- AC/ECEB:DEST:NRR
- EAD:DEST:NRR
RJKiessel
PCWu
CEMcCracken
JRichardson
07/16/87
07/16/87
07/16/87
07/16/87
IN 87-XX
July xx, 1987 The Trojan plant is conducting a failure analysis on the degraded
determine the causes and mechanisms involved in the observed wall
event. The NRC is evaluating the data available and has formed a
determine any generic implication of the event.
components to
thinning
task force to
Related Generic Communications:
IE Information Notice 82-22, "Failure in Turbine Exhaust Lines," dated July 9,
1982 provides additional information pertaining to erosion/corrosion in wet
steam piping. Other erosion/corrosion events pertaining specifically to the
feedwater systems (including emergency and auxiliary feedwater) have occurred
in feedwater pump minimum-flow lines, J-tubes in steam generator feedwater
rings, and emergency feedwater supply to a helium circulator.
IE Information Notice 86-106, "Feedwater Line Break," was issued December 16,
1986. It described the then-known details of the December 9, 1986 failure of
the suction line to the main feedwater pump at Surry Power Station Unit 2.
Supplement 1 to this information notice, which was issued February 13, 1987, provided additional detail on the failure mechanism. Supplement 2, which was
issued on March 10, 1987, discussed the effects of the system interactions that
resulted from the line break.
NRC Bulletin 87-01, "Thinning of Pipe Wall in
July 9, 1987, requested that licensees submit
programs for monitoring the thickness of pipe
and two-phase carbon steel piping systems.
Nuclear Power Plants," issued on
information concerning their
walls in high-energy single-phase
No specific action or written response is required by this information notice.
If you have any questions about this matter, please contact the Regional
Administrator of the appropriate NRC regional office or this office.
Charles E. Rossi, Director
Division of Operational Event Assessment
Office of Nuclear Reactor Regulation
Technical Contact:
Paul C. Wu, NRR
(301) 492-8987 Attachment: List of Recently Issued IE Information Notices
- SEE PREVIOUS CONCURRENCES
D/DOEA:NRR
CERossi
07/ /87
- OGCB:DOEA:NRR
- ECEB:DEST:NRR
RJKiessel
PCWu
07/16/87
07/16/87 C/OGCB:DOEAiNRR
CHBerling ' if
07/~t/87
- AC/ECEB:DEST:NRR
CEMcCracken
07/16/87
- PPMB:ARM
TechEd
07/28/87
- EAD:DEST:NRR
JRichardson
07/16/87
IN 87-XX
July xx, 1987 The Trojan Power Station is conducting a failure analysis on the degraded
components to determine the causes and mechanisms involved in the observed wall
thinning event. The NRC is evaluating the data available and has formed a task
force to determine any generic implication of the event.
Related Generic Communications:
TE Information Notice 82-22, "Failure in Turbine Exhaust Lines," dated July 9,
1982 provides additional information pertaining to erosion/corrosion in wet
steam piping. Other erosion/corrosion events pertaining specifically to the
feedwater systems (including emergency and auxiliary feedwater) have occurred
in feedwater pump minimum flow lines, J-tubes in steam generator feedwater
rings, and emergency feedwater supply to a helium circulator.
Information Notice 86-106, "Feedwater Line Break," was issued December 16,
1986. It described the, then known, details of the December 9, 1986, failure
of the suction line to the main feedwater pump at Surry Power Station Unit 2.
Supplement 1 to this information notice, which was issued February 13, 1987, provided additional detail on the failure mechanism. Supplement 2, which was
issued on March 10, 1987, discussed the effects of the system interactions
which resulted from the line break.
NRC Bulletin 87-01, "Thinning of Pipe Wall in Nuclear Power Plants," issued on
July 9, 1987, requested that licensees submit information concerning their
programs for monitoring the thickness of pipe walls in high-energy single-phase
and two-phase carbon steel piping systems.
No specific action or written response is required by this information notice.
If you have any questions about this matter, please contact the Regional
Administrator of the appropriate NRC regional office or this office.
Charles E. Rossi, Director
Division of Operational Event Assessment
Office of Nuclear Reactor Regulation
Technical Contact:
Paul C. Wu, NRR
(301) 492-8987 Attachment: List of Recently Issued IE Information Notices
- SEE PREVIOUS CONCURRENCES
D/DOEA:NRR
C/OGCB:DOEA:NRR
PPMB:ARJ4 CERossi
CHBerlinger
TechEd
'
07/
/87
07/
/87
07/1V/87
- OGCB:DOEA:NRR
- ECEB:DEST:NRR
- AC/ECEB:DEST:NRR
- EAD:DEST:NRR
RJKiessel
PCWu
CEMcCracken
JRichardson
07/16/87
07/16/87
07/16/87
07/16/87
.
.
P
IN 87-XX
July xx, 1987 Related Generic Communications:
IE Information Notice 82-22, "Failure in Turbine Exhaust Lines," dated July 9,
1982 provides additional information pertaining to erosion/corrosion in wet
steam piping.
Other erosion/corrosion events pertaining specifically to the
feedwater systems (including emergency and auxiliary feedwater) have occurred
in feedwater pump minimum flow lines, J-tubes in steam generator feedwater
rings, and emergency feedwater supply to a helium circulator.
Information Notice 86-106, "Feedwater Line Break," was issued December 16,
1986.
It described the, then known, details of the December 9, 1986, failure
of the suction line to the main feedwater pump at Surry Power Station Unit 2.
Supplement 1 to this information notice, which was issued February 13, 1987, provided additional detail on the failure mechanism. Supplement 2, which was
issued on March 10, 1987, discussed the effects of the system interactions
which resulted from the line break.
NRC Bulletin 87-01, "Thinning of Pipe Wall in
July 9, 1987, requested that licensees submit
programs for monitoring the thickness of pipe
and two-phase carbon steel piping systems.
Nuclear Power Plants," issued on
information concerning their
walls in high-energy single-phase
No specific action or written response is required by this information notice.
If you have any questions about this matter, please contact the Regional
Administrator of the appropriate NRC regional office or this office.
Charles E. Rossi, Director
Division of Operational Event Assessment
Office of Nuclear Reactor Regulation
Technical Contact:
Paul C. Wu, NRR
(301) 492-8987 Attachment: List of Recently Issued IE Information Notices
OGCB:DOEA:NRR
RJKiessel
07/1)/87 D/DOEA:NRR
CERossi
07/ /87 ECEB:
- NRR
PCWu FA<4
07//,/87 C/OGCB:DOEA:NRR
CHBerlinger
07/ /87 AC/ECEB:DEST}NR
CEMcCracke ¢("L__
071/4 /87
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07/ #/87