Information Notice 1989-30, High Temperature Environments at Nuclear Power Plants
UNITED STATES
NUCLEAR REGULATORY COMMISSION
OFFICE OF NUCLEAR REACTOR REGULATION
WASHINGTON, D.C. 20555
November 1, 1990
NRC INFORMATION NOTICE NO. 89-30, SUPPLEMENT 1:
HIGH TEMPERATURE ENVIRONMENTS
AT NUCLEAR POWER PLANTS
Addressees
All holders of operating licenses or construction permits for nuclear power
reactors.
Purpose
This information notice supplement is being provided to present additional
information regarding the effects of elevated room temperature on the
operability of safety related equipment as discussed in NRC Information Notice 89-30, issued March 15, 1989.
It is expected that recipients will review the
information for applicability to their facilities and consider actions, as
appropriate, to avoid similar problems. However, suggestions contained in
this information notice do not constitute NRC requirements; therefore, no
specific action or written response is required.
Description of Circumstances
Information Notice No. 89-30 described events where elevated temperatures and
high humidity within the drywell or containment adversely impacted the
operability of safety related equipment.. This supplement describes events
where high ambient temperatures in areas other than the containment or the
drywell caused the failure or degradation of'safety related equipment.
On June 25, 1990, the Omaha Public Power District (the licensee) conducted a
full load test on the No. 1 emergency diesel generator (EDG) at Fort Calhoun
Unit 1. This test was conducted to establish a temperature profile for the'
EDG room. The test was terminated when the output from the generator became
erratic as a result of the failure of a transistor in the static exciter
circuitry.
The licensee's investigationlrevealed that the transistor had failed because of
the effects of elevated temperatures in the static exciter/voltage regulator
cabinet which was located in the EDG room. Temperatures in the cabinet had
reached 140 degrees Fahrenheit (F) during the test. The transistor was-replaced
and the EDG was returned to operable status. The licensee also discovered
elevated temperatures in the static exciter/voltage regulator cabinet for the
No. 2 EDG.
In a recently completed engineering analysis, the licensee verified
that because of inadequate cabinet ventilation, a potential common mode failure
of both EDGs exists. The analysis also concluded that this condition has likely
existed since plant startup.
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IN,
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IN b-,30, Supplement I
November 1, 1990 To reduce the potential for heat bujildup in the cabinets, the cabinet doors were
temporarily--removed until a long term solution to the. problem can be formulated.
The licensee's investigation of this event also revealed that elevated room tem- peratures significantly impact the operating efficiency of the EDGs and could
lead to accelerated degradation.
Discussion:
The Fort Calhoun Station has two General Motors EMD 20-645E4,diesel generator
sets. The cooling system for each EDG consists of an engine radiator, an
engine-driven fan, and a.
pump that circulates cooling water through the engine
and radiator. Outside air is drawn into the EDG room by the fan, is blown
across the radiator, and exits through the roof of the building through air
ducts. Inlet air for the diesel turbocharger is drawn directly from the EDG
room.
In June 1988 the licensee modified the hangers on the diesel'exhaust headers.
These modifications required that the insulating material on the
headers be removed. After removing the insulating material, the licensee
was aware'that ambient temperature would increase. Therefore, the licensee
performed an analysis to support a design change that would allow the exhaust
headers to remain uninsulated. The analysis concluded that bulk temperature in
the EDG rooms would rise by only 9 degrees F and that this increase would not
have an adverse effect on the operability of the EDGs.
The analysis did not
!'
' 1 ' specfically ddresthei'effect"of elevated room temperature on other equipment-
-located infthe room.:
'
-
..
When test runs were made during the summer months of 1989, the licensee found
that bulk room temperatures actually increased approximately 20 degrees F, or
more than twice the increase'predicted by the licensee's analysis. This ele- vated room temperature likely accelerated the degradation of the exciter com-,
ponent that failed. However, the potential for the temperature buildup in the
unvented cabinet probably existed since the cabinets were installed.
The licensee also has determined that the 20 degree rise in ambient temperature
resulted in an increase in jacket water temperature and turbocharger. inlet air
temperature., These temperature increases adversely affect engine operating
efficiency. Depending on the amount of increase, elevated jacket water
temperature and/or turbocharger inlet air temperature, combined with heavy
loading, may lead to accelerated degradation of the engine.
This degradation
could result in engine failure or prevent the engine from meeting its designed
run time as assumed in the Final Safety Analysis Report. To reduce the poten- tial for engine degradation while operating during periods of high ambient
temperatures, unit loading would have to be limited. Derating the EDG could
result in the unit's dependable output capability being less than required for
design basis accident loads.
Because of variations in the configurations of intake air systems, turbocharger
inlet air may be preheated significantly. The temperature of the air entering
the turbocharger may be much.higher than air temperature elsewhere. ,Also,,
water-to-air heat exchangers are more sensitive to changes in ambient temperature
- ", .
": I
.
, I 2 .
IN E
30, Supplement 1 November 1, 1990 than are water-to-water heat exchangers.
However, an increase in service water
temperature in water-to-water heat exchangers may also result in the derating
of an EDG. The NRC is!aware of other instances in which elevated ambient tempv- eratures resulted in the failure or degradation of safety related components.
To avoid excessive cabinet temperatures and subsequent component failures, the
licensee for the Washington Nuclear Project, Unit 2, has instituted admin- istrative procedures to remove the doors from the static exciter voltage
regulator cabinet when the EDG room temperature exceeds 90 degrees F. The
licensee performed an analysis which concluded that internal temperatures in
the cabinets would exceed the long-term (greater than 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />) thermal'rating
of the cabinet components if'the EDG room temperature were to exceed 90 degrees F.
Extended operation at or above this temperature would significantly increase the
probability of a component failure.
On December 16, 1985, the failure of a fan in an engineered safety features
(ESF) cabinet at Palo Verde Unit 1 resulted in the spurious actuation of several
ESF signals.
These signals initiated the automatic start of the Train A EDG,-
caused loads to be shed from the"Train A vital bus, and initiated the operation
of the ESF load sequencer. The load shed signal did not clear, prohibiting the
automatic or manual sequencing of ESF electrical loads. The licensee installed, a control room alarm that annunciates on cabinet exit air high temperature.
On June 4, 1984, at the McGuire Station, a total loss of control area ventilation
resulted in~temperature build-up in instrumentation cabinets. ;The elevated -j
<WI
temperatures initiated several spurious solid state protection system alarms and
resulted in the'operators having to reduce output from both generating units.
This event is described in detail in IE Information Notice No. 85-89, "Potential
Loss of Solid State'Instrumentation Following Failure of Control Room Cooling."
On September 21, 1982, a similar event occurred at Davis-Besse Unit 1, and
involved the failure of a 48-volt power supply in the'-Steam aind'Feedwater Rupture
Control System (SFRCS). The failure of the power supply was attributed toiheat
buildup in the SFRCS cabinets. The licensee installed fans in the cabinets to
ensure more effective cooling.
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 NRR project manager.
(hAarle E.Ros;s, Director
Division of Operational Events Assessment
Office of Nuclear Reactor Regulation
Technical Contacts: C. Paulk, Region IV
(817) 860-8236
N. Fields, NRR
(301) 492-1173 Attachment:
List of Recently Issued NRC Information Notices
Attachment 1
89-30, Supplement 1
November 1, 1990
Page I of I
LIST OF RECENTLY ISSUED
-
NRC INFORMATION NOTICES
Iotic1
90-69 a No.
Subhiect
Adequacy of Emergency And
Essential Lighting
90-68
Stress Corrosion Cracking
of Reactor Coolant Pump Bolts
90-67
Potential Security Equipment
Weaknesses
90-66
Incomplete Draining and
Drying of Shipping Casks
8843.
High Radiation Hazards
Supp. 1
From Irradiated Incoro
Detectors and Cables
90-65
Recent Orifice Plate
Problems
90-64 Potential for Coaon-Mode
Failure Of High Pressure
Safety Injection Pumps or
Release of Reactor Coolant
Outside Containment During
A ton-Of-Coolant Accident--
uAte ot
Issuance
10/31/90
10/30/90
10/29/90
10/25/90
10/5/90
10/5/90
10/4/90
Issued to
All holders of OLs
or CPs for nuclear
power reactors.
All holders of OLs
or CPs for pres- surized water
reactors (PWRs).
All holders of OLs
or CPs for
nuclear power
reactors and
Category I fuel
facilities.
All holders of OLs
for nuclear
power reactors
and all registered
users of XRC
approved waste
shipping packages.
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 pres- surized-water
reactors.
DI0
- Operating License
- Construction Permit
UNITED STATES
NUCLEAR REGULATORY COMMISSION
WASHINGTON. D.C. 20555
OFFICIAL BUSINESS
PENALTY FOR PRIVATE USE. $300
FRST CLASS MAKt
POSTAGEI FEES PAIO
UItRC
. PRMIT N-. 0-7
IN 89-30, Supplement 1 November 1, 1990 than are water-to-water heat exchangers.
However, an increase in service water
temperature in water-to-water heat exchangers may also result in the derating
of an EDG. The NRC is aware of other instances in which elevated ambient temp- eratures resulted in the failure or degradation of safety related components.
To avoid excessive cabinet temperatures and subsequent component failures, the
licensee for the Washington Nuclear Project, Unit 2, has instituted admin- istrative procedures to remove the doors from the static exciter voltage
regulator cabinet when the EDG room temperature exceeds 90 degrees F. The
licensee performed an analysis which concluded that internal temperatures in
the cabinets would exceed the long-term (greater than 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />) thermal rating
of the cabinet components if the EDG room temperature were to exceed 90 degrees F.
Extended operation at or above this temperature would significantly increase the
probability of a component failure.
On December 16, 1985, the failure of a fan in an engineered safety features
(ESF) cabinet at Palo Verde Unit 1 resulted in the spurious actuation of several
ESF signals.
These signals initiated the automatic start of the Train A EDG,
caused loads to be shed from the Train A vital bus, and initiated the operation
of the ESF load sequencer. The load shed signal did not clear, prohibiting the
automatic or manual sequencing of ESF electrical loads. The licensee installed
a control room alarm that annunciates on cabinet exit air high temperature.
On June 4, 1984, at the McGuire Station, a total loss of control area ventilation
resulted in temperature build-up in instrumentation cabinets. The elevated
temperatures initiated several spurious solid state protection system alarms and
resulted in the operators having to reduce output from both generating units.
This event is described in detail in IE Information Notice No. 85-89, "Potential
Loss of Solid State Instrumentation Following Failure of Control Room Cooling."
On September 21, 1982, a similar event occurred at Davis-Besse Unit 1, and
involved the failure of a 48-volt power supply in the Steam and Feedwater Rupture
Control System (SFRCS). The failure of the power supply was attributed to heat
buildup in the SFRCS cabinets. The licensee installed fans in the cabinets to
ensure more effective cooling.
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 NRR project manager.
Charles E. Rossi, Director
Division of Operational Events Assessment
Office of Nuclear Reactor Regulation
Technical Contacts: C. Paulk, Region IV
(817) 860-8236
N. Fields, NRR
(301) 492-1173 Attachment: List of Recently Issued NRC Information Notices
- See previous concurrence
OFC :NRR:EAB
- REGION IV :TECH ED
- SC/NRR/EAB :BC/NRR/EAB :BC/NRR/GC
- DD/NRR/DOEA
_____
__
_
_
_______
__-______-____-____--
NAME :*EFIELDS
- CPAULK
- DFISHER
- ACHAFFEE
- CBERLINGER
DATE ://90
0
/ /90
/90
/90
- //90
Document Name: 89-30, SUPP. 1
1
IN 8941', SUP 1 October XX, 1990 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 NRR project manager.
Charles E. Rossi, Director
Division of Operational Events Assessment
Office of Nuclear Reactor Regulation
Technical Contact:
C. Paulk, Region IV
(817) 860-8236- C
N. Fields, NRR
(301) 492-1173 Attachment:
List of Recently Issued NRC Information Notices
- See previous concurrence
OFC :NRR:EAB
- REGION IV :TECH ED
- SSJCNRR/EAB
- BCJNRR/EAB :tC "tC
- DD/NRR/DOEA
_____: --
____________
_
_
_____-__
NAME :*EFIELDS
- CPAULK
- DFISHER
- ACHAFFEE
- CBERLINGER :CROSSI1 DATE:
- 1o1J71 I
- (D/P.Z/
- /T
Document Name:
FTCALHOUN IN
To avoid excessive cabinet temperatures and subsequent component failures, the
licenfe for the Washington Nuclear Project, Unit 1, has instituted administrative
procedur
to remove the doors from the static exciter voltage regulator cabinet
when the E
room temperature exceeds 90 degrees F. The licensee performed an analysis
which conclu
that internal temperatures in the cabinets would exceed the
long-term (grea
than 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />) thermal rating of the cabinet components if
the EDG room tempe ture were to exceed 90 degrees F. Extended operation at or
above this temperatu
would significantly increase the probabilty of a component
failure.
On June 4, 1984, at the M
ire Station, a total loss of control area ventilation
resulted in temperature bui -up in instrumentation cabinets. The elevated tempera- tures initiated several spur
s solid state protection system alarms and resulted
in the operators having to redu
output from both generating units. This event is
described in detail in IE Informa ion Notice No. 85-89, "Potential Loss of Solid
State Instrumentation Following Fai ure of Control Room Cooling."
On September 21, 1982, a similar event ccurred at Davis-Besse Unit 1, and involved
the failure of a 48-volt power supply in the Steam and Feedwater Rupture Control
System (SFRCS).
The failure of the power upply was attributed to heat build-up in the
SFRCS cabinets. The licensee installed fa
in the cabinets to ensure more
effective cooling.
On December 16, 1985, the failure of a fan in a engineered safety features (ESF)
cabinet at Palo Verde Unit 1 resulted in the spur ous actuation of several ESF
signals. These signals initiated the automatic st t of the Train A EDG, caused
loads to be shed from the Train A vital bus, and in iated the operation of
the ESF load sequencer. The load shed signal did not lear, prohibiting the
automatic or manual sequencing of ESF electrical loads
The licensee installed
a control room alarm that annunciates on cabinet exit ai
high temperature.
This information notice requires no specific action or wri ten response. If you
have any questions about the information in this notice, pl se contact one of
the technical contacts listed below or the appropriate NRR pr ect manager.
Charles E. Rossi, Director
Division of Operational Evens Assessment
Office of Nuclear Reactor Regulation
Technical Contact:
C. Paulk, Region IV
(817) 860-8236
N. Fields, NRR
(301) 492-1173 Attachment:
List of Recently Issued NRC Information Notices
- See previous concurrence
INA?9 z
d
OFC
- NRR:EAB
- REGION IV :TECH ED
- SC R1t/EAB :BC/NRR/EAB :BC/NRR/GC
- DD/NRR/DOEA
NAME :EFIELD
- CPAULK
- DFISHER
- ACHAFFEE
- CBERLINGER :CROSSI
DATE * /:Y
q
'°/iq//c
OFFICIAL RECORD COPY
Document Name: FTCALHOUN IN
To avoid excessive cabinet temperatures and subsequent component failures, the
licensee for the Washington Nuclear Project Unit 1 has instituted administrative
procedures to remove the static ex-citer voltage regulator cabinet doors when the
EDG roo stemperature exceeds 90 degrees F. The licensee performed an analysis
which cont uded that internal temperatures in the cabinets would exceed the
long-term ( eater than 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />), thermal rating of the cabinet components if
the EDG room
mperature were to exceed 90 degrees F. Extended operation at
this temperatur or higher would significantly increase the probabilty that a
component failure ould occur.
On June 4, 1984, at t Mcquire Station, a total loss of control area ventilation
resulted in temperature uild-up in instrumentation cabinets. The elevated tempera- tures initiated several s rious solid state protection system alarms and resulted
in a operators having to re ce output from both generating units. This event is
described in detail in IE Inf mation Notice No. 85-89, "Potential Loss of Solid
State Instrumentation Following ailure of Control Room Cooling".
A similar event occurred at Davis- sse 1 on September 21, 1982 and involved the
failure of a 48-volt power supply in he Steam and Feedwater Rupture Control System
(SFRCS). The failure of the power sup y was attributed to heat build-up in the
SFRCS cabinets. The licensee installed
ns in the cabinets to ensure more effective
cooling.
On December 16, 1985, the failure of a fan in n engineered safety features (ESF)
cabinet at Palo Verde Unit 1 resulted in the sp rious actuation of several ESF
signals. A spurious auto-start of the train A E , operation of the ESF load
sequencer, and a train A load shed signal. The lo d shed signal did not clear, prohibiting the automatic or manual sequencing of E
electrical loads. The
licensee installed a control room alarm which annunci e on high cabinet exit
air temperature.
This information notice requires no specific action or wri en response.
If you
have any questions about the information in this notice, ple se contact the
technical contact listed below or the appropriate NRR project anager.
Charles E. Rossi, Director
Division of Operational Events ssessment
Office of Nuclear Reactor Regul ion
Technical Contact:
C. Paulk, Region IV
(817) 860-8236
N. Fields, NRR
(301) 492-1173 Attachment:
List of Recently Issued NRC Information Notices
OFC :NRR:EAB
- REGION IV :TECH ED
- SC/NRR/EAB :BC/NRR/EAB :BC/NRR/GC
- DD/NRR/DOEA
NAME :NFIELDS
- CPAULK
- TJH;;nI
- DFISHER
- ACHAFFEE
- CBERLINGER :CROSSI
DATE :
- IOqJqo
OFFICIAL RECORD COPY
Document Name:
FTCALHOUN IN