Information Notice 1989-54, Potential Overpressurization of the Component Cooling Water System
UNITED STATES
NUCLEAR REGULATORY COMMISSION
OFFICE OF NUCLEAR REACTOR REGULATION
WASHINGTON, D.C.
20555
June 23, 1989
NRC INFORMATION NOTICE NO. 89-54: POTENTIAL OVERPRESSURIZATION OF THE
COMPONENT COOLING WATER SYSTEM
Addressees
All holders of operating licenses or construction permits for nuclear power
reactors.
Purpose
This information notice Is being provided to alert addressees to potential
problems resulting from failure of the component cooling water tubing within
the thermal barrier heat exchanger of a reactor coolant pump.
It is expected
that recipients will review the information for applicability to their facili- ties and consider actions, as appropriate, to avoid similar problems.
However, suogestions contained in this information notice do not constitute NRC require- ments; therefore, no specific action or written response is required.
Description of Circumstances
On May 15, 1989, the licensee for Surry Power Station informed the NRC of a
design deficiency in the component cooling water (CCW) system.
The deficiency
results from underdesign in relief capacity of the CCW lines connected to the
thermal barrier heat exchangers on the reactor coolant pumps. The reactor
coolant pumps at Surry were manufactured by Westinghouse and rely on heat
removal by the CCW system in conjunction with seal injection for reactor
coolant pump seal and lower radial bearing. cooling. The reactor coolant pump
motors are also cooled by component cooling water.
Component cooling water flows through the thermal barrier heat exchangers
within 1/2-inch ID tubes.
At the request of the licensee for Surry, Westing- house calculated the maximum reactor coolant flow rate that could occur from a
break in a thermal barrier tube. Westinghouse calculated the flow rate into
the CCW system assuming a double ended break of the 1/2-inch ID tube. The
calculation modeled the reactor coolant flow upstream of the break and the flow
out the break into the CCW system. An inleakage of approximately 275 gpm was
predicted.
The CCW piping adjacent to the reactor coolant pumps at Surry is of schedule
160 carbon steel and is designed to withstand full reactor system pressure.
The lower-pressure sections of the CCW system within containment and within the
auxiliary building are designed for 150 psig.
In the event of reactor coolant
i
- T
77 --
IN 89-54 June 23, 1989 system inleakage, the low-pressure sections of CCW piping are protected from
overpressure by a check valve on the upstream side of the reactor coolant pump
thermal barrier and by a fast-closing, air-operated valve on the downstream
side.
The isolation valve is designed to close on a high CCW flow signal.
In
addition, a relief valve which is located on the upstream side of the thermal
barrier is designed to open at 150 psig. The licensee determined that this
protection was not adequate to protect the low-pressure parts of the CCW system
from overpressure if the calculated inleakage (approximately 275 gpm) were to
occur.
The air-operated isolation valve is not safety related and the relief
valve is only designed to pass 167 gpm.
Isolation valves are provided on the
CCW lines outside the containment building, but these are not designed to
withstand reactor system pressure.
Failure to isolate the leak inside contain- ment or to provide adequate relieving capacity could lead to an unisolatable
reactor coolant leak outside the containment building. The licensee is in- stalling additional relief capacity on the CCW lines upstream and downstream of
the reactor coolant thermal barrier heat exchangers at both Surry plants.
In July 1984, Westinghouse notified the NRC (in accordance with 10 CFR Part 21)
of a similar problem involving potential overpressure of CCW systems at 18 plants with CCW systems designed by Westinghouse. These plants were equipped
with a CCW surge tank vent valve that would close automatically on high radio- activity in the CCW system. Westinghouse stated that in the event that reactor
coolant inleakage resulted in closure of the vent valve, the CCW system could -
be overpressurized downstream of the CCW pumps. At the time of the 10 CFR Part
- 21 n"tification, Westinghouse Tndicated that a thermal ba-rrieFrtube rupture
would result in a leak rate of approximately 260 gpm. Westinghouse recommended
several corrective measures designed to ensure continual venting of the surge
tank, thereby preventing overpressurization of the low-pressure CCW system.
The CCW system at Surry was not designed by Westinghouse and Surry was, there- fore, not included with the 18 plants identified by Westinghouse in the 10 CFR
Part 21 notification.
In view of the potential for CCW over-pressurization
identified at Surry, other plant owners may wish to evaluate protection of
low-pressure CCW piping from overpressure in the event of failure of the
reactor coolant pump thermal barrier tubing.
No specific action or written response is required by this information notice.
If you have any questions about this matter, please contact one of the techni- cal contacts listed below or the Regional Administrator of the appropriate
regional office.
har
Rs
ssij
~reto
Division of Operational Events Assessment
Office of Nuclear Reactor Regulation
Technical Contacts: William Lefave, NRR
(301) 492-0862
Walton Jensen, NRR
(301) 492-1190
Attachment:
List of Recently Issued NRC Information Notices
Attachment
June 23, 1989 LIST OF RECENTLY ISSUED
NRC INFORMATION NOTICES
Information
Date of
Notice No.
Subject
Issuance
Issued to
89-53
Rupture of Extraction
Steam Line on High
Pressure Turbine
6/13/89
All holders of OLs
or CPs for nuclear
power reactors.
88-46, Supp. 3
89-52
89-51
Licensee Report of
Defective Refurbished
Circuit Breakers
Potential Fire Damper
Operational Problems
Potential Loss of Required
Shutdown Margin During
Refueling Operations
6/8/89
6/8/89
5/31/89
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.
88-88,
-
Supp. 1
Degradation of Westinghouse
--ARD Relays--
5/31/89
__
All holders of OLs
-
or CPs for-nucleare
power reactors.
89-50
89-49
89-48
89-47
89-46
Inadequate Emergency
Diesel Generator Fuel
Supply
Failure to Close Service
Water Cross-Connect
Isolation Valves
Design Deficiency in the
Turbine-Driven Auxiliary
Feedwater Pump Cooling
Water System
Potential Problems With
Worn or Distorted Hose
Clamps on Self-Contained
Breathing Apparatus
Confidentiality of
Exercise Scenarios
5/30/89
5/22/89
5/22/89
5/18/89
5/11/89
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 and
fuel facilities.
All holders of licenses
for fuel cycle facilities
and byproduct material
licensees having an
approved emergency
response plan.
OL = Operating License
CP = Construction Permit
IN 89-54 June 23, 1989 system inleakage, the low-pressure sections of CCW piping are protected from
overpressure by a check valve on the upstream side of the reactor coolant pump
thermal barrier and by a fast-closing, air-operated valve on the downstream
side. The isolation valve is designed to close on a high CCW flow signal.
In
addition, a relief valve which is located on the upstream side of the thermal
barrier is designed to open at 150 psig. The licensee determined that this
protection was not adequate to protect the low-pressure parts of the CCW system
from overpressure if the calculated inleakage (approximately 275 gpm) were to
occur. The air-operated isolation valve is not safety related and the relief
valve is only designed to pass 167 gpm.
Isolation valves are provided on the
CCW lines outside the containment building, but these are not designed to
withstand reactor system pressure.
Failure to isolate the leak inside contain- ment or to provide adequate relieving capacity could lead to an unisolatable
reactor coolant leak outside the containment building. The licensee is in- stalling additional relief capacity on the CCW lines upstream and downstream of
the reactor coolant thermal barrier heat exchangers at both Surry plants.
In July 1984, Westinghouse notified the NRC (in accordance with 10 CFR Part 21)
of a similar problem involving potential overpressure of CCW systems at 18 plants with CCW systems designed by Westinghouse. These plants were equipped
with a CCW surge tank vent valve that would close automatically on high radio- activity in the CCW system. Westinghouse stated that in the event that reactor
coolant inleakage resulted in closure of the vent valve, the CCW system could
be overpressurized downstream of the CCW pumps. At the time of the 10 CFR Part
21 notification, Westinghouse indicated that a thermal barrier tube rupture
would result in a leak rate of approximately 260 gpm. Westinghouse recommended
several corrective measures designed to ensure continual venting of the surge
tank, thereby preventing overpressurization of the low-pressure CCW system.
The CCW system at Surry was not designed by Westinghouse and Surry was, there- fore, not included with the 18 plants identified by Westinghouse in the 10 CFR
Part 21 notification. In view of the potential for CCW over-pressurization
identified at Surry, other plant owners may wish to evaluate protection of
low-pressure CCW piping from overpressure in the event of failure of the
reactor coolant pump thermal barrier tubing.
No specific action or written response is required by this information notice.
If you have any questions about this matter, please contact one of the techni- cal contacts 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: William Lefave, NRR
(301) 492-0862
Walton Jensen, NRR
(301) 492-1190
Attachment:
List of Recently Issued NRC Information Notices
- SEE PREVIOUS CONCURRENCES
06/ft89
- EAB:NRR
- EAB:NRR *TECH:ED *NRR:SLPB
- C:DEST:NRR *C:EAB:NRR *C:O B:NRR
WJensen:db RLobel
BLefave
LShao
WDLanning CHBerlinger
06/09/89
06/09/89 06/08/89 06/13/89
06/14/89
06/15/89
06/15/89
IN 89- June , 1989 v overpressure by a check valve on the upstream side of the reactor coolant
pumps and by a fast-closing, air-operated valve on the downstream side. The
isolation valve Is designed to close on a high CCW flow signal. In addition.
a relief valve which is located on the upstream side of the thermal barrier is
designed to open at 150 psig. The licensee determined that this protection
was not adequate to protect the low-pressure parts of the CCW system from
overpressure if the calculated inleakage (approximately 275 gpm) were to occur.
The air-operated isolation valve is not safety related and the relief valve is
only designed to pass 167 gpm.
Isolation valves are provided on the CCW lines
outside the containment building, but these are not designed to withstand
reactor system pressure. The licensee is installing additional relief capacity
on the CCW lines upstream and downstream of the reactor coolant thermal barrier
heat exchangers at both Surry plants.
In July 1984, Westinghouse notified the NRC (in accordance with 10 CFR Part 21)
of a similar problem involving potential overpressure of CCW systems at 18 plants with CCW systems designed by Westinghouse. These plants were equipped
with a CCW surge tank vent valve that would close automatically on high
radioactivity in the CCW system. Westinghouse stated that in the event
that reactor coolant inleakage resulted in closure of the vent valve, the CCW
system could be overpressurized downstream of the CCW pumps. At the time of
the 10 CFR Part 21 notification, Westinghouse indicated that a thermal barrier
tube rupture would result in a leak rate of approximately 260 gpm. Westinghouse
recommended several corrective measures designed to ensure continual venting of
the surge tank, thereby preventing overpressurization of the low-pressure CCW
system. The CCW system at Surry was not designed by Westinghouse and Surry
was, therefore, not included with the 18 plants identified by Westinghouse in the
10 CFR Part 21 notification. In view of the potential for CCW over- pressurization identified at Surry. other plant owners may wish to evaluate
protection of low-pressure CCW piping from overpressure in the event of
failure of the reactor coolant pump thermal barrier tubing.
No specific action or written response is required by this information notice.
If you have any questions about this matter, please contact one of the
technical contacts 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 William Lefave, NRR
(301) 492-0862
Walton Jensen, NRR
(301) 492-1190
Attachment: List of Recently Issued NRC Information Notices
- SEE PREVIOUS CONCURRENCES
- EAB:NRR
- EAB:NRR *TECH:ED *NRR:SLPB
- C:DEST:NRR *C:EAB:NRR C:OGCB:NRR
WJensen:db RLobel
BLefave
LShao
WDLanning CHBerlinger
/ /89
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IN 89- June , 1989
'_>
< overpressure by a check valve on the upstream side of the reactor coolant
pumps and by a fast-closing, air-operated valve on the downstream side. The
Isolation valve is designed to close on a high CCVI flow signal.
In addition, a relief valve which is located on the upstream side of the thermal barrier is
designed to open at 150 psig. The licensee determined that this protection
was not adequate to protect the low-pressure parts of the CCW system from
overpressure if the calculated inleakage (approximately 275 gpm) were to occur.
The air-operated Isolation valve is not safety related and the relief valve is
only designed to pass 167 gpm.
Isolation valves are provided on the CCW lines
outside the containment building, but these are not designed to withstand
reactor system pressure. The licensee is installing additional relief capacity
on the CCW lines upstream and downstream of the reactor coolant thermal barrier
heat exchangers at both Surry plants.
In July 1984, Westinghouse notified the NRC (in accordance with 10 CFR Part 21)
of a similar problem involving potential overpressure of CCW systems at 18 plants with CCW systems designed by Westinghouse. These plants were equipped
with a CCW surge tank vent valve that would close automatically on high
radioactivity in the CCW system.
Westinghouse stated that in the event
that reactor coolant inleakage resulted in closure of the vent valve, the CCW
system could be overpressurized downstream of the CCW pumps.
At the time of
the 10 CFR Part 21 notification, Westinghouse indicated that a thermal barrier
tube rupture would result in a leak rate of approximately 260 gpm. Westinghouse
recommended several corrective measures designed to ensure continual venting of
the surge tank, thereby preventing overpressurization of the low-pressure CCW
system.
The CCW system at Surry was not designed by Westinghouse and Surry was
therefore not included with the 18 plants Identified by Westinghouse in the
10 CFR Part 21 notification. In view of the potential for CCW over- pressurization identified at Surry, other plant owners may wish to evaluate
protection of low-pressure CCW piping from overpressure in the event of
failure of the reactor coolant pump thermal barrier tubing.
No specific action or written response is required by this information notice.
If you have any questions about this matter, please contact one of the
technical contacts 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 William Lefave, NRR
(301) 492-0862
Walton Jensen, NRR
(301) 492-1190
Attachment: List of Recently Is ued NRC Information No I
- SEE PREVIOUS CONCURRENCE
- EAB:NRR
EAB:NRR *TECH:ED NRR L B
- T:NRR C: AB: VR C:OGCB:NRR
WJensen:db RLobel
89BLe av
o
WDLann ng CHBerlinger
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/
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/
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CERossi
/
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IN 89- June , 1989 a CCW surge tank vent valve that would close automatically on high
radioactivity in the CCW system. Westinghouse stated that in the event
reactor coolant inleakage resulted in closure of the vent valve, that the CCW
system could be overpressurized overpressure downstream of the CCW pumps.
At the time of the 10 CFR 21 notification Westinghouse indicated that a
thermal barrier tube rupture would result in a leak rate of approximately
260 gpm. Westinghouse recommended several corrective measures designed to
ensure continual venting of the surge tank thereby preventing overpressurization
of the low pressure CCW system. The CCW system at Surry was not designed by
Westinghouse and Surry was therefore not included with the 18 plants identified
by Westinghouse in the 10 CFR 21 notification. Based on the potential for
CCW overpressurizatlon identified at Surry, other plant owners may wish to
evaluate protection of low pressure CCW piping from overpressure in the event
of reactor coolant pump thermal barrier tubing failure.
No specific action or written response is required by this Information Notice.
If you have any questions about this matter, please contact one of the
technical contacts 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 William Lefave, NRR
(301) 492-0862
Walton Jensen, NRR
(301) 492-1190
Attachment:
List of Recently Issued NRC Information Notices
qL-
- SEE PREVIOUS CONCURRENCE
- EAB:NRR
EAB:NRR TECH:ED
NRR:SLPB C:DEST:NRR C:EAB:NRR C:OGCB:NRR
WJensen:db RLobel
BLefave
LShao
WDLanning CHBerlinger
b'T'89 4/' /89
6/ /89
/ /89
/ /89
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CERossi
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