Information Notice 1994-90, Transient Resulting in a Reactor Trip and Multiple Safety Injection System Actuations at Salem: Difference between revisions

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{{#Wiki_filter:UNITED STATES NUCLEAR REGULATORY
{{#Wiki_filter:UNITED STATES


COMMISSION
NUCLEAR REGULATORY COMMISSION


===OFFICE OF NUCLEAR REACTOR REGULATION===
OFFICE OF NUCLEAR REACTOR REGULATION
WASHINGTON, D.C. 20555 December 30, 1994 NRC INFORMATION


NOTICE 94-90: TRANSIENT
WASHINGTON, D.C. 20555 December 30, 1994 NRC INFORMATION NOTICE 94-90:   TRANSIENT RESULTING IN A REACTOR TRIP


RESULTING
AND MULTIPLE SAFETY INJECTION SYSTEM


IN A REACTOR TRIP AND MULTIPLE SAFETY INJECTION
ACTUATIONS AT SALEM
 
SYSTEM ACTUATIONS
 
AT SALEM


==Addressees==
==Addressees==
All holders of operating
All holders of operating licenses or construction permits for nuclear power
 
licenses or construction


permits for nuclear power reactors.
reactors.


==Purpose==
==Purpose==
The U.S. Nuclear Regulatory
The U.S. Nuclear Regulatory Commission (NRC) is issuing this information
 
Commission (NRC) is issuing this information
 
notice to alert addressees
 
to the events associated
 
with the loss of circulating
 
water at Salem Nuclear Power Plant, Unit 1, on April 7, 1994, that led to a reactor trip followed by multiple automatic
 
actuations
 
of the safety injection


system. It is expected that recipients
notice to alert addressees to the events associated with the loss of


will review the information
circulating water at Salem Nuclear Power Plant, Unit 1, on April 7, 1994, that


for applicability
led to a reactor trip followed by multiple automatic actuations of the safety


to their facilities
injection system. It is expected that recipients will review the information


and consider actions, as appropriate, to avoid similar problems.
for applicability to their facilities and consider actions, as appropriate, to


However, suggestions
avoid similar problems. However, suggestions contained in this information


contained
notice are not NRC requirements; therefore, no specific action or written


in this information
response is required.
 
notice are not NRC requirements;
therefore, no specific action or written response is required.Description
 
of Circumstances


==Description of Circumstances==
On April 7, 1994, at 10:00 a.m., Salem, Unit 1 was in Mode 1 at 73-percent
On April 7, 1994, at 10:00 a.m., Salem, Unit 1 was in Mode 1 at 73-percent


power. Public Service Electric and Gas Company (the licensee)  
power. Public Service Electric and Gas Company (the licensee) was operating
was operating the unit at reduced power because river detritus (marsh grass) had fouled the circulating
 
water intake structure
 
causing a reduction
 
in condenser
 
cooling efficiency.
 
In response, the operators
 
decreased
 
the power level of Unit 1 to approximately
 
60 percent because of an increase in condenser
 
back pressure caused by grass fouling of the traveling
 
screens at the intake structure.
 
In response to an impending
 
loss of circulating
 
water, the operators
 
began reducing load by 1 percent per minute. However, in rapid succession, several of the Unit 1 traveling
 
screens became clogged with grass, causing the associated
 
pumps to trip, until only 1 circulating
 
water pump remained running. As the pumps were lost from service, operators
 
increased
 
the rate of the load reduction
 
to 8 percent per minute.Operators
 
attempted
 
to reduce unit load as rapidly as reactor power was being decreased
 
by insertion
 
of control rods and addition of boron. The effort caused a power mismatch that resulted in a slight, but continuing, increase in reactor coolant temperature.
 
===In response, the nuclear shift supervisor===
directed the operator controlling
 
reactor power to go to the electrical
 
distribution
 
control panel and shift plant electrical
 
loads to offsite power sources. Although operators
 
believed that the plant was stable, they failed P/)p rz Woee dD. Soqo 7W/2 30 9412270233 I&lcj-r u1 I/S/95 KJ~IN 94-90 December 30, 1994 to recognize
 
that reactor power was still decreasing
 
because of the delayed effect of a previous addition of boron. This caused a reversal of the power mismatch and resulted in reactor coolant system (RCS) temperature
 
decreasing
 
to below the minimum temperature
 
at which criticality
 
is allowed. The operators
 
attempted
 
to restore RCS temperature
 
by increasing
 
reactor power from approximately


7 percent to 25 percent. However, since power had been below 10 percent, the power range "high neutron flux-low setpoint" trip had been automatically
the unit at reduced power because river detritus (marsh grass) had fouled the


reinstated, establishing
circulating water intake structure causing a reduction in condenser cooling


25-percent
efficiency. In response, the operators decreased the power level of Unit 1 to


reactor power as the trip setpoint.
approximately 60 percent because of an increase in condenser back pressure


When power reached 25 percent, the reactor automatically
caused by grass fouling of the traveling screens at the intake structure. In


tripped.Almost immediately, train 'A" of the safety injection (SI) logic actuated on a high steam flow signal coincident
response to an impending loss of circulating water, the operators began


with low RCS temperature. (Later investigation
reducing load by 1 percent per minute. However, in rapid succession, several


revealed that the high steam flow signal was actually the result of a pressure wave created in the main steam lines when the turbine stop valves closed as a result of the turbine trip). In response to the reactor trip and safety injection, the operators
of the Unit 1 traveling screens became clogged with grass, causing the


entered the plant emergency
associated pumps to trip, until only 1 circulating water pump remained


operating procedures.
running. As the pumps were lost from service, operators increased the rate of


The SI logic did not reposition
the load reduction to 8 percent per minute.


all necessary
Operators attempted to reduce unit load as rapidly as reactor power was being


components
decreased by insertion of control rods and addition of boron. The effort


to the expected, post-actuation
caused a power mismatch that resulted in a slight, but continuing, increase in


position because the initiating
reactor coolant temperature. In response, the nuclear shift supervisor


signal was so short.The operators
directed the operator controlling reactor power to go to the electrical


manually repositioned
distribution control panel and shift plant electrical loads to offsite power


the affected components
sources. Although operators believed that the plant was stable, they failed


to their proper positions.
P/)p          rz    dD. Soqo


At 11:00 a.m., the licensee declared an unusual event based on a"manual or automatic
Woee                      7W/2 30
9412270233                            I


emergency
&lcj-r u1  I/S/95


core cooling system actuation
KJ~
                                                              IN 94-90
                                                              December 30, 1994 to recognize that reactor power was still decreasing because of the delayed


with a discharge to the vessel." When the operators
effect of a previous addition of boron. This caused a reversal of the power


took action to reset the SI logic, they discovered
mismatch and resulted in reactor coolant system (RCS) temperature decreasing


that train "B" of the SI logic had not actuated, indicating
to below the minimum temperature at which criticality is allowed. The


an apparent logic error.As the operators
operators attempted to restore RCS temperature by increasing reactor power


were attempting
from approximately 7 percent to 25 percent. However, since power had been


to stabilize
below 10 percent, the power range "high neutron flux-low setpoint" trip had


the plant, the RCS continued
been automatically reinstated, establishing 25-percent reactor power as the


to heat up because of reactor decay heat combined with reactor coolant pump heat.Steam generator
trip setpoint. When power reached 25 percent, the reactor automatically


pressure increased
tripped.


but was not automatically
Almost immediately, train 'A" of the safety injection (SI) logic actuated on a


relieved by the steam generator
high steam flow signal coincident with low RCS temperature. (Later


atmospheric
investigation revealed that the high steam flow signal was actually the result


relief valves because of a pre-existing
of a pressure wave created in the main steam lines when the turbine stop


condition that prevented
valves closed as a result of the turbine trip). In response to the reactor


the proper automatic
trip and safety injection, the operators entered the plant emergency operating


operation
procedures. The SI logic did not reposition all necessary components to the


of the valves. Concurrently, because of RCS heatup and the volume of water added by the safety injection, the pressurizer
expected, post-actuation position because the initiating signal was so short.


filled to a solid condition, and the pressurizer
The operators manually repositioned the affected components to their proper


power-operated relief valves cycled several hundred times to control RCS pressure.A short time later, steam generator
positions. At 11:00 a.m., the licensee declared an unusual event based on a


pressure increased
"manual or automatic emergency core cooling system actuation with a discharge


in the "11" and "13" steam generators
to the vessel." When the operators took action to reset the SI logic, they


to the safety valve lift setpoint.
discovered that train "B" of the SI logic had not actuated, indicating an


The opening of a safety valve caused a rapid cooldown and depressurization
apparent logic error.


of the RCS that was magnified
As the operators were attempting to stabilize the plant, the RCS continued to


by the solid condition
heat up because of reactor decay heat combined with reactor coolant pump heat.


of the system. RCS pressure rapidly reached the automatic
Steam generator pressure increased but was not automatically relieved by the


SI setpoint of 1755 psig, and since train "B" of the SI logic had remained armed, a second automatic
steam generator atmospheric relief valves because of a pre-existing condition


SI actuation
that prevented the proper automatic operation of the valves. Concurrently, because of RCS heatup and the volume of water added by the safety injection, the pressurizer filled to a solid condition, and the pressurizer power- operated relief valves cycled several hundred times to control RCS pressure.


occurred.
A short time later, steam generator pressure increased in the "11" and "13"
steam generators to the safety valve lift setpoint. The opening of a safety


At about the same time, operators
valve caused a rapid cooldown and depressurization of the RCS that was


manually initiated
magnified by the solid condition of the system. RCS pressure rapidly reached


safety injection
the automatic SI setpoint of 1755 psig, and since train "B" of the SI logic


in response to the rapidly decreasing
had remained armed, a second automatic SI actuation occurred. At about the


RCS pressure.
same time, operators manually initiated safety injection in response to the


After the second safety injection, operators remained in the emergency
rapidly decreasing RCS pressure. After the second safety injection, operators


operating
remained in the emergency operating procedures, and continued their attempts


procedures, and continued
to stabilize plant conditions. The pressurizer relief tank rupture disk


their attempts to stabilize
actuated because of increasing tank pressure caused by the volume of RCS water


plant conditions.
relieved to the pressurizer relief tank from the pressurizer power-operated
 
The pressurizer
 
relief tank rupture disk actuated because of increasing
 
tank pressure caused by the volume of RCS water relieved to the pressurizer
 
relief tank from the pressurizer
 
power-operated


relief valves.
relief valves.


IN 94-90 December 30, 1994 The operators
IN 94-90
                                                                December 30, 1994 The operators controlled plant pressure using the charging and letdown


controlled
provisions of the chemical and volume control system because normal RCS


plant pressure using the charging and letdown provisions
pressure control was not available due to the solid condition of the system.


of the chemical and volume control system because normal RCS pressure control was not available
At 1:16 p.m., licensee management declared an alert to ensure activation of


due to the solid condition
the Salem Technical Support Center to provide the Salem operators with


of the system.At 1:16 p.m., licensee management
additional technical assistance to support cooldown of the plant.


declared an alert to ensure activation
Accordingly, the Technical Support Center was fully staffed.


of the Salem Technical
At 3:11 p.m., the operators established a steam bubble in the pressurizer


Support Center to provide the Salem operators
using pressurizer heaters. At 4:30 p.m., operators restored pressurizer level


with additional
to the normal band and returned level control to automatic. They subsequently


technical
exited the emergency operating procedures and used the integrated operating


assistance
procedures to cool the plant down to Mode 4 (Hot Shutdown), which was achieved


to support cooldown of the plant.Accordingly, the Technical
at 1:06 a.m. on April 8, and then to Mode 5 (Cold Shutdown), which was


Support Center was fully staffed.At 3:11 p.m., the operators
achieved at 11:24 a.m. on the same day.


established
Discussion


a steam bubble in the pressurizer
On April 8, 1994, the NRC dispatched an Augmented Inspection Team to


using pressurizer
investigate the event. The results of that inspection were documented in NRC


heaters. At 4:30 p.m., operators
Inspection Report 50-272/94-80, dated June 24, 1994. Although several issues


restored pressurizer
emerged from the NRC investigation of this event, three specific aspects are


level to the normal band and returned level control to automatic.
of particular concern. These aspects are discussed below.


===They subsequently===
Solid State Protection System Logic Mismatch: During the first SI actuation, the "A" and "B" logic trains of the solid state protection system were
exited the emergency


operating
mismatched. Train "A" sensed and responded to conditions representative of a


procedures
steam line break accident, namely a low RCS temperature coincident with a high


and used the integrated
steam line flow. Although these conditions were real indications, the RCS low


operating procedures
temperature was due to operator error and the high steam flow was a transient


to cool the plant down to Mode 4 (Hot Shutdown), which was achieved at 1:06 a.m. on April 8, and then to Mode 5 (Cold Shutdown), which was achieved at 11:24 a.m. on the same day.Discussion
signal induced by a pressure wave resulting from the closure of the turbine


On April 8, 1994, the NRC dispatched
stop and control valves. This transient signal had a duration of about 30
milliseconds, which system response testing later showed was sufficient for


an Augmented
certain portions of the "A" logic to respond, but of insufficient duration for


Inspection
the "B" logic to respond. The logic mismatch appears to be a result of the


Team to investigate
variations in response sensitivity to the steam flow input relays. The


the event. The results of that inspection
licensee modified the design to require a longer signal duration before the


were documented
logic is actuated so that such transient signals would not result in an


in NRC Inspection
undesired safety injection.


Report 50-272/94-80, dated June 24, 1994. Although several issues emerged from the NRC investigation
Nuclear Instrument Rod Shadowing: Before the initial reactor trip, when the


of this event, three specific aspects are of particular
operators were raising reactor power to restore RCS temperature, the


concern. These aspects are discussed
intermediate range and power range nuclear instruments were not in agreement


below.Solid State Protection
with respect to indicated power. The intermediate range detectors were


System Logic Mismatch:
"trailing" the power range by about 5 to 10 percent. This led to a condition
During the first SI actuation, the "A" and "B" logic trains of the solid state protection


system were mismatched.
in which the reactor was tripped at the 25-percent power range setpoint before


Train "A" sensed and responded
the rod block signal was received from the intermediate range detectors at


to conditions
20-percent power. The discrepancy between the power and intermediate range


representative
nuclear instruments was apparently due to "rod shadowing."


of a steam line break accident, namely a low RCS temperature
IN 94-90
                                                              December 30, 1994 The combination of the cool RCS and the rod pattern resulting from the down


coincident
power maneuver shielded the intermediate range detectors, causing the


with a high steam line flow. Although these conditions
instruments to indicate a lower power than the power range detectors.


were real indications, the RCS low temperature
Although this bias was within an acceptable envelope for detector operability, the response of the instruments was not initially understood. This led to


was due to operator error and the high steam flow was a transient signal induced by a pressure wave resulting
concern that the nuclear instruments were not properly operating.


from the closure of the turbine stop and control valves. This transient
Control Room Command and Control: Before the initial reactor trip, shift


signal had a duration of about 30 milliseconds, which system response testing later showed was sufficient
management directed staff to support actions necessary to restore circulating


for certain portions of the "A" logic to respond, but of insufficient
water. The Shift Technical Advisor, a senior reactor operator assigned to the


duration for the "B" logic to respond. The logic mismatch appears to be a result of the variations
work control station, was directed to assist in the restoration of affected


in response sensitivity
equipment. The extra duty reactor operator was directed to assist at the


to the steam flow input relays. The licensee modified the design to require a longer signal duration before the logic is actuated so that such transient
intake structure. The senior shift supervisor was initially in the control


signals would not result in an undesired
room area, but subsequently left to go to the turbine building. This


safety injection.
deployment of licensed operators led to minimal staffing of the control room


Nuclear Instrument
at the onset of the transient.


Rod Shadowing:
During this time, the operators were preparing to take the unit turbine off
Before the initial reactor trip, when the operators


were raising reactor power to restore RCS temperature, the intermediate
line, and the reactor controls operator was directed by the shift supervisor


range and power range nuclear instruments
to initiate actions to transfer plant electrical loads. This led to the


were not in agreement with respect to indicated
reactor controls watch station not being staffed during a reactivity change.


power. The intermediate
The RCS began to cool as a result of a slight power mismatch between the


range detectors
reactor and the turbine. When the shift supervisor first discovered this


were"trailing" the power range by about 5 to 10 percent. This led to a condition in which the reactor was tripped at the 25-percent
mismatch, he began to raise reactor power to restore temperature, which led to


power range setpoint before the rod block signal was received from the intermediate
a momentary loss of the command oversight function. He subsequently


range detectors
recognized the need to maintain an overall command posture and stopped


at 20-percent
withdrawing control rods. However, he continued to allow the reactor controls


power. The discrepancy
operator to swap the electrical loads and the RCS temperature continued to


between the power and intermediate
decrease. When the reactor controls operator completed the electrical plant


range nuclear instruments
realignment, the shift supervisor then directed him to raise reactor power to


was apparently
restore RCS temperature. The shift supervisor did not discuss the fact that


due to "rod shadowing."
he had manipulated the control rods with the reactor controls operator, and
IN 94-90 December 30, 1994 The combination


of the cool RCS and the rod pattern resulting
his direction to the relatively inexperienced operator lacked specificity (how


from the down power maneuver shielded the intermediate
far or how fast to raise power). The operator subsequently raised reactor


range detectors, causing the instruments
power until the 25-percent power trip was reached.


to indicate a lower power than the power range detectors.
===Related Generic Communications===
*      NRC Information Notice 94-55, "Problems with Copes-Vulcan Pressurizer


Although this bias was within an acceptable
Power-Operated Relief Valves," August 4, 1994.


envelope for detector operability, the response of the instruments
This information notice discusses cracking of plug material, severe wear


was not initially
of plugs and cages, and a problem with the misalignment and galling of a


understood.
stem in the power-operated relief valves discovered as a result of valve


This led to concern that the nuclear instruments
inspection subsequent to the April 7, 1994, event.


were not properly operating.
*      NRC Information Notice 94-36, "Undetected Accumulation of Gas in Reactor


Control Room Command and Control: Before the initial reactor trip, shift management
Coolant System," May 24, 1994.


directed staff to support actions necessary
This information notice discusses lack of operator awareness of an


to restore circulating
accumulation of nitrogen in the reactor vessel head during cooldown and


water. The Shift Technical
depressurization of the RCS subsequent to the April 7, 1994, event.


Advisor, a senior reactor operator assigned to the work control station, was directed to assist in the restoration
IN 94-90
                                                            December 30, 1994 This information notice requires no specific action or written response. If


of affected equipment.
you have any questions about the information in this notice, please contact


The extra duty reactor operator was directed to assist at the intake structure.
the technical contact listed below or the appropriate Office of Nuclear


The senior shift supervisor
Reactor Regulation (NRR) project manager.


was initially
rian K. Grimes, Director


in the control room area, but subsequently
Division of Project Support


left to go to the turbine building.
Office of Nuclear Reactor Regulation


This deployment
Technical contacts:  Robert J. Summers, RI


of licensed operators
(609) 935-3850
                      Eric J. Benner, NRR


led to minimal staffing of the control room at the onset of the transient.
(301) 504-1171 Attachment:


During this time, the operators
===List of Recently Issued NRC Information Notices===
hiW          54-r      11J cGi.,7-"4


were preparing
K>
                                                              Attachment


to take the unit turbine off line, and the reactor controls operator was directed by the shift supervisor
IN 94-90
                                                                December 30, 1994 LIST OF RECENTLY ISSUED


to initiate actions to transfer plant electrical
NRC INFORMATION NOTICES


loads. This led to the reactor controls watch station not being staffed during a reactivity
Information                                  Date of


change.The RCS began to cool as a result of a slight power mismatch between the reactor and the turbine. When the shift supervisor
Notice No.             Subject                Issuance      Issued to


first discovered
94-89          Equipment Failures at          12/28/94      All U.S. Nuclear Regulatory


this mismatch, he began to raise reactor power to restore temperature, which led to a momentary
Irradiator Facilities                        Commission irradiator


loss of the command oversight
licensees.
 
function.
 
===He subsequently===
recognized
 
the need to maintain an overall command posture and stopped withdrawing
 
control rods. However, he continued
 
to allow the reactor controls operator to swap the electrical
 
loads and the RCS temperature
 
continued
 
to decrease.
 
When the reactor controls operator completed
 
the electrical
 
plant realignment, the shift supervisor
 
then directed him to raise reactor power to restore RCS temperature.
 
The shift supervisor
 
did not discuss the fact that he had manipulated
 
the control rods with the reactor controls operator, and his direction
 
to the relatively
 
inexperienced
 
operator lacked specificity (how far or how fast to raise power). The operator subsequently
 
raised reactor power until the 25-percent
 
power trip was reached.Related Generic Communications
 
* NRC Information
 
Notice 94-55, "Problems


with Copes-Vulcan
94-88          Inservice Inspection          12/23/94    All holders of OLs or CPs


Pressurizer
Deficiencies Result in                      for pressurized water


Power-Operated
Severely Degraded Steam                    reactors.


Relief Valves," August 4, 1994.This information
Generator Tubes


notice discusses
94-87          Unanticipated Crack in a      12/22/94      All holders of OLs or CPs


cracking of plug material, severe wear of plugs and cages, and a problem with the misalignment
Particular Heat of                           for nuclear power reactors.


and galling of a stem in the power-operated
Alloy 600 Used for


relief valves discovered
Westinghouse Mechanical


as a result of valve inspection
Plugs for Steam Generator


subsequent
Tubes


to the April 7, 1994, event.* NRC Information
94-86          Legal Actions Against          12/22/94    All holders of OLs or CPs


Notice 94-36, "Undetected
Thermal Science, Inc.,                      for nuclear power reactors.


Accumulation
Manufacturer of Thermo-Lag


of Gas in Reactor Coolant System," May 24, 1994.This information
94-85          Problems with the              12/21/94      All holders of OLs or CPs


notice discusses
Latching Mechanism                          for nuclear power reactors.


lack of operator awareness
in Potter and Brumfield


of an accumulation
R1O-E3286-2 Relays


of nitrogen in the reactor vessel head during cooldown and depressurization
94-40,        Failure of a Rod Control        12/15/94    All holders of OLs or CPs


of the RCS subsequent
Supp. 1        Cluster Assembly to Fully                    for nuclear power reactors.


to the April 7, 1994, event.
Insert Following a Reactor


IN 94-90 December 30, 1994 This information
Trip at Braidwood Unit 2
94-84          Air Entrainment in Terry        12/02/94    All holders of OLs or CPs


notice requires no specific action or written response.
Turbine Lubricating Oil                      for nuclear power reactors.


If you have any questions
System


about the information
89-25,        Unauthorized Transfer of        12/07/94    All fuel cycle and material


in this notice, please contact the technical
Rev. 1        Ownership or Control of                      licensees.


contact listed below or the appropriate
Licensed Activities


Office of Nuclear Reactor Regulation (NRR) project manager.rian K. Grimes, Director Division of Project Support Office of Nuclear Reactor Regulation
94-83         Reactor Trip Followed by       12/06/94     All holders of OLs or CPs
 
Technical
 
contacts:
Robert J. Summers, RI (609) 935-3850 Eric J. Benner, NRR (301) 504-1171 Attachment:
List of Recently Issued NRC Information
 
Notices hiW 54-r cGi. ,7-"4 K>Attachment
 
IN 94-90 December 30, 1994 LIST OF RECENTLY ISSUED NRC INFORMATION
 
NOTICES Information
 
Date of Notice No. Subject Issuance Issued to 94-89 94-88 94-87 94-86 94-85 94-40, Supp. 1 94-84 89-25, Rev. 1 94-83 Equipment
 
Failures at Irradiator
 
Facilities
 
Inservice
 
Inspection
 
Deficiencies
 
Result in Severely Degraded Steam Generator
 
Tubes Unanticipated
 
Crack in a Particular
 
Heat of Alloy 600 Used for Westinghouse
 
Mechanical
 
Plugs for Steam Generator Tubes Legal Actions Against Thermal Science, Inc., Manufacturer
 
of Thermo-Lag
 
Problems with the Latching Mechanism in Potter and Brumfield R1O-E3286-2 Relays Failure of a Rod Control Cluster Assembly to Fully Insert Following
 
a Reactor Trip at Braidwood
 
Unit 2 Air Entrainment
 
in Terry Turbine Lubricating
 
Oil System Unauthorized
 
Transfer of Ownership
 
or Control of Licensed Activities
 
Reactor Trip Followed by Unexpected
 
Events 12/28/94 12/23/94 12/22/94 12/22/94 12/21/94 12/15/94 12/02/94 12/07/94 12/06/94 All U.S. Nuclear Regulatory
 
Commission
 
irradiator
 
licensees.


All holders of OLs or CPs for pressurized
Unexpected Events                            for nuclear power reactors.


water 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.All holders of OLs or CPs for nuclear power reactors.All fuel cycle and material licensees.
OL = Operating License


All holders of OLs or CPs for nuclear power reactors.OL = Operating
CP = Construction Permit


License CP = Construction
IN 94-XX


Permit
November xx, 1994 This information notice requires no specific action or written response. If


IN 94-XX November xx, 1994 This information
you have any questions about the information in this notice, please contact


notice requires no specific action or written response.
the technical contact listed below or the appropriate Office of Nuclear


If you have any questions
Reactor Regulation (NRR) project manager.


about the information
Brian K. Grimes, Director


in this notice, please contact the technical
Division of Project Support


contact listed below or the appropriate
Office of Nuclear Reactor Regulation


Office of Nuclear Reactor Regulation (NRR) project manager.Brian K. Grimes, Director Division of Project Support Office of Nuclear Reactor Regulation
Technical contacts:  Robert J. Summers


Technical
(609) 935-3850
                      Eric J. Benner


contacts: Robert J. Summers (609) 935-3850 Eric J. Benner (301) 504-1171 Attachment:
(301) 504-1171 Attachment:   List of Recently Issued NRC Information Notices
List of Recently Issued NRC Information


Notices E-mailed to John White and Robert Summers of Region I for review on 10/21/94.OFC OECB:DOPS
E-mailed to John White and Robert Summers of Region I for review on 10/21/94.


PUB:ADM SC/OECB:DOPS
OFC    OECB:DOPS        PUB:ADM           SC/OECB:DOPS     BC/SRXB:DSSA


BC/SRXB:DSSA
NAME  EBenner          Tech Ed*          EGoodwin*        RJones*
DATE  11/14/94      110/17/94
                      .-
                                        110/24/94
                                        .I.


NAME EBenner Tech Ed* EGoodwin*
,10/26/94 OFC   OECB:DOPS         BC/OECB:DOPS      D/DOPS
RJones*DATE 11/14/94 110/17/94
110/24/94
,10/26/94-..I.OFC OECB:DOPS BC/OECB:DOPS


D/DOPS NAME RKiessel*  
NAME   RKiessel*         AChaffee*         BGrime
AChaffee*  
BGrime DATE 11/02/94 11/16/94 / /94[OFFICIAL


RECORD COPY]DOCUMENT NAME: S:\DOP S SEC\SALEM.IN
DATE 11/02/94            11/16/94            / /94
[OFFICIAL RECORD COPY]           DOCUMENT NAME:       S:\DOP S SEC\SALEM.IN


IN 94-XX November xx, 1994 This information
IN 94-XX


notice requires no specific action or written response.
November xx, 1994 This information notice requires no specific action or written response. If


If you have any questions
you have any questions about the information in this notice, please contact


about the information
the technical contact listed below or the appropriate Office of Nuclear


in this notice, please contact the technical
Reactor Regulation (NRR) project manager.


contact listed below or the appropriate
I


Office of Nuclear Reactor Regulation (NRR) project manager.I Brian K. Grimes, Director Division of Projects Support Office of Nuclear Reactor Regulation
Brian K. Grimes, Director


Technical
Division of Projects Support


contact: Robert J. Summers (609) 935-3850 Eric J. Benner (301) 504-1171 Attachment:
Office of Nuclear Reactor Regulation
1. List of Recently Issued NRC Information


Notices E-mailed to John White and Robert Summers of Region I for review on 10/21/94.OFC lOECB:DOPS
Technical contact:            Robert J. Summers


PUB:ADM SC/OECB:DOPS
(609) 935-3850
                              Eric J. Benner


BC/SRXB:DSSA
(301) 504-1171 Attachment:
1.        List of Recently Issued NRC Information Notices


NAME EBenner Tech Ed* EGoodwin*
E-mailed to John White and Robert Summers of Region I for review on 10/21/94.
RJones*DATE 1 11/14/94 10/17/94 10/24/94 110/26/94
_ j OFC OECB:DOPS BC/OLCB:DOPS


D/DOPS NAME RKiessel*
OFC      lOECB:DOPS      PUB:ADM              SC/OECB:DOPS             BC/SRXB:DSSA
e BGrimes DATE 111/02/94
1/ 1 n/94 J / /94-- -- --I maAEI- II AIA&Ir P -% r I LU[ICLIAL


KtLUKU LUfYJ MUUUMtN I NAMLI;U ; \ Cd JB1\SALEM.IN
NAME        EBenner      Tech Ed*            EGoodwin*                  RJones*
  DATE    111/14/94        10/17/94            10/24/94                110/26/94 _ j


K>j IN 94-XX November xx, 1994 This information
OFC        OECB:DOPS    BC/OLCB:DOPS        D/DOPS


notice requires no specific action or written response.
NAME        RKiessel*            e          BGrimes


If you have any questions
DATE 111/02/94          1/    1    n/94J / /94                  r  I


about the information
-- --  -                          -I maAEI- II AIA&Ir    P - %
  LU[ICLIAL KtLUKU LUfYJ              MUUUMtN I NAMLI;        U ; \ Cd  JB1\SALEM.IN


in this notice, please contact the technical
K>j


contact listed below or the appropriate
IN 94-XX


Office of Nuclear Reactor Regulation (NRR) project manager.Brian K. Grimes, Director Division of Projects Support Office of Nuclear Reactor Regulation
November xx, 1994 This information notice requires no specific action or written response. If


Technical
you have any questions about the information in this notice, please contact


contact: Eric J. Benner (301) 504-1171 Attachment:
the technical contact listed below or the appropriate Office of Nuclear
1. List of Recently Issued NRC Information


Notices E-mailed to John White and Robert Summers of Region I for review on 10/21/94.OFC OECB:DOPS
Reactor Regulation (NRR) project manager.


l PUB:ADM SC/OECB:DOPS
Brian K. Grimes, Director


BC/SRXB:DSSA
Division of Projects Support


NAME EBenner Tech Ed* EGoodwin*
Office of Nuclear Reactor Regulation
RJones*DATE 11 /c2/94 10/17/94 j10/24/94
110/26/94
1 T Ifi-nrC gFErpfnPS


., RC/OECB:DOPS
Technical contact:          Eric J. Benner


D/DOPS____-1 -t --- --.NAME RKi tsel A AChaffee BGrimes DATE _V)//I94 I / /94 / /94..- fr.r -1[OFFICIAL
(301) 504-1171 Attachment:
1.     List of Recently Issued NRC Information Notices


RECORD COPY]UUUvlMMI NAMt: U : Xr J B1\SALEM.IN
E-mailed to John White and Robert Summers of Region I for review on 10/21/94.


v)IN 94-XX November, xx, 1994 shift supervisor
OFC    OECB:DOPS      l PUB:ADM            SC/OECB:DOPS          BC/SRXB:DSSA


was initially
NAME  EBenner          Tech Ed*            EGoodwin*              RJones*
  DATE  11 /c2/94        10/17/94          j10/24/94              110/26/94      1 T                                        Ifi-
  ____-1 nrC          t


in the control room area, but subsequently
gFErpfnPS


left to go to the turbine building.
-    . , RC/OECB:DOPS -- --.  D/DOPS


This deployment
NAME  RKi tsel A        AChaffee            BGrimes


of licensed staffing led to minimal staffing of the control room at the onset of the transient.
DATE _V)//I94        I      /  /94              /  /94
                                                ..-            fr.r


During this time, the operators
-1
  [OFFICIAL RECORD COPY]            UUUvlMMI    NAMt:      U : Xr  JB1\SALEM.IN


were preparing
v)
                                                                            IN 94-XX


to take the unit turbine off-line, and the reactor controls operator was directed by the shift supervisor
November, xx, 1994 shift supervisor was initially in the control room area, but subsequently left


to initiate actions to transfer plant electrical
to go to the turbine building. This deployment of licensed staffing led to


loads. This led to the reactor controls watch station not being manned during a reactivity
minimal staffing of the control room at the onset of the transient. During this


change. The RCS began to cool as a result of a slight power mismatch between the reactor and the turbine. When first identified
time, the operators were preparing to take the unit turbine off-line, and the


by the shift supervisor, he began to raise reactor power to restore temperature, which led to a momentary
reactor controls operator was directed by the shift supervisor to initiate


loss of the command function.
actions to transfer plant electrical loads. This led to the reactor controls


The shift supervisor
watch station not being manned during a reactivity change. The RCS began to cool


subsequently
as a result of a slight power mismatch between the reactor and the turbine. When


recognized
first identified by the shift supervisor, he began to raise reactor power to


the need to maintain an overall command posture and stopped withdrawing
restore temperature, which led to a momentary loss of the command function. The


control rods. However, he continued
shift supervisor subsequently recognized the need to maintain an overall command


to allow the reactor controls operator to swap the electrical
posture and stopped withdrawing control rods. However, he continued to allow the


loads and RCS temperature
reactor controls operator to swap the electrical loads and RCS temperature


continued
continued to degrade.            When the reactor controls operator completed the


to degrade. When the reactor controls operator completed
electrical plant realignment, the shift supervisor then directed him to raise


the electrical
reactor power to restore RCS temperature. This direction was not specific as to


plant realignment, the shift supervisor
how far to raise power, which, coupled with the operator's inexperience, led to


then directed him to raise reactor power to restore RCS temperature.
the operator raising reactor power until reaching the 25 percent power trip.


This direction
===Related Generic Communications===
      -        NRC IN 94-55, 'Problems with Copes-Vulcan Pressurizer Power-Operated


was not specific as to how far to raise power, which, coupled with the operator's
Relief Valves,' August 4, 1994.


inexperience, led to the operator raising reactor power until reaching the 25 percent power trip.Related Generic Communications
-        NRC IN 94-36, Undetected Accumulation of Gas in Reactor Coolant


-NRC IN 94-55, 'Problems
System," May 24, 1994.


with Copes-Vulcan
This information notice requires no specific action or written response. Ifyou


Pressurizer
have any questions about the information in this notice, please contact the


Power-Operated
technical contact listed below or the appropriate Office of Nuclear Reactor


Relief Valves,' August 4, 1994.-NRC IN 94-36, Undetected
Regulation (NRR) project manager.


Accumulation
Brian K. Grimes, Director


of Gas in Reactor Coolant System," May 24, 1994.This information
Division of Projects Support


notice requires no specific action or written response.
Office of Nuclear Reactor Regulation


If you have any questions
Technical contact:            Eric J. Benner


about the information
(301) 504-1171 Attachments:
1.    List of Recently Issued NRC Information Notices


in this notice, please contact the technical
E-mailed to John White and Robert Summers of Region I for review on l1/19/94.


contact listed below or the appropriate
OFC      OECB:DOPS          PUB:ADM        lSC/OECB:DOPS          SRXB:DSSV


Office of Nuclear Reactor Regulation (NRR) project manager.Brian K. Grimes, Director Division of Projects Support Office of Nuclear Reactor Regulation
NAME    EBenner  Wi    X Tech Ed A M    c iiEGoodwi n 1iJ            I


Technical
DATE eA    //gV/94        10/rt1/94                                    /94
                        -                                            11 OFC    I BC/SRXB:DSSin I BC/OECB:DOPS I D/DOPS                  I


contact: Eric J. Benner (301) 504-1171 Attachments:
NAME    RJoneb    %I/    IAChaffee          BGrimes
1. List of Recently Issued NRC Information


Notices E-mailed to John White and Robert Summers of Region I for review on l1/19/94.OFC OECB:DOPS
DATE      g    94 /- -..Y    / /94 O          / /94 A E          .,      A    .


PUB:ADM l SC/OECB:DOPS
[O. I A -          -                    E


SRXB:DSSV NAME EBenner Wi X Tech Ed A M c iiEGoodwi
[OFFICIAL RECORD COPYJ              DOCUMENT NAME:         U:XLJBl\SALtM.IN


n 1iJ I DATE eA //gV/94 10 / rt1/94 /94-11 OFC I BC/SRXB:DSSin
W


I BC/OECB:DOPS
IN 94-90
                                                                    December 30, 1994 This information notice requires no specific action or written response. If


I D/DOPS I NAME RJoneb %I/ I AChaffee BGrimes DATE g 94 / / /94 / /94[O. I A ---Y O E A E ., A .-..[OFFICIAL
you have any questions about the information in this notice, please contact


RECORD COPYJ DOCUMENT NAME: U:XLJBl\SALtM.IN
the technical contact listed below or the appropriate Office of Nuclear


W IN 94-90 December 30, 1994 This information
Reactor Regulation (NRR) project manager.


notice requires no specific action or written response.
WOW 1gd. le-by


If you have any questions
Kdo


about the information
L Omet


in this notice, please contact the technical
Brian K. Grimes, Director


contact listed below or the appropriate
Division of Project Support


Office of Nuclear Reactor Regulation (NRR) project manager.WOW 1gd. le-by Kdo L Omet Brian K. Grimes, Director Division of Project Support Office of Nuclear Reactor Regulation
Office of Nuclear Reactor Regulation


Technical
Technical contacts:    Robert J. Summers, RI


contacts: Robert J. Summers, RI (609) 935-3850 Eric J. Benner, NRR (301) 504-1171 Attachment:
(609) 935-3850
List of Recently Issued NRC Information
                        Eric J. Benner, NRR


Notices DOCUMENT NAME: 94-90. IN*See previous concurrences
(301) 504-1171 Attachment:
  List of Recently Issued NRC Information Notices


E-mailed to John White and Robert Summers of Region I for review on 10/21/94.OFC OECB:DOPS
DOCUMENT NAME:  94-90. IN


PUB:ADM SC/OECB:DOPS
*See previous concurrences


BC/SRXB:DSSA
E-mailed to John White and Robert Summers of Region I for review on 10/21/94.


NAME EBenner Tech Ed* EGoodwin*
OFC   OECB:DOPS         PUB:ADM        SC/OECB:DOPS     BC/SRXB:DSSA
RJones*DATE 111/14/94
1 10/17/94 10/24/94 _ /710/26/94 OFC OECB:DOPS BC/OECB:DOPS


l~ -IF -e- --NAME RKiessel*  
NAME EBenner          Tech Ed*        EGoodwin*        RJones*
AChaffee*DATE 11/02/94 11/16/94 j12/Z7/94[OFFICIAL
    DATE 111/14/94        1 10/17/94       10/24/94     _  /710/26/94 OFC  OECB:DOPS        BC/OECB:DOPS


RECORD COPY]}}
l~            - IF -
                                            -e-      -
    NAME  RKiessel*        AChaffee*
    DATE  11/02/94          11/16/94      j12/Z7/94
              [OFFICIAL RECORD COPY]}}


{{Information notice-Nav}}
{{Information notice-Nav}}

Revision as of 04:30, 24 November 2019

Transient Resulting in a Reactor Trip and Multiple Safety Injection System Actuations at Salem
ML031060383
Person / Time
Site: Beaver Valley, Millstone, Hatch, Monticello, Calvert Cliffs, Dresden, Davis Besse, Peach Bottom, Browns Ferry, Salem, Oconee, Mcguire, Nine Mile Point, Palisades, Palo Verde, Perry, Indian Point, Fermi, Kewaunee, Catawba, Harris, Wolf Creek, Saint Lucie, Point Beach, Oyster Creek, Watts Bar, Hope Creek, Grand Gulf, Cooper, Sequoyah, Byron, Pilgrim, Arkansas Nuclear, Braidwood, Susquehanna, Summer, Prairie Island, Columbia, Seabrook, Brunswick, Surry, Limerick, North Anna, Turkey Point, River Bend, Vermont Yankee, Crystal River, Haddam Neck, Ginna, Diablo Canyon, Callaway, Vogtle, Waterford, Duane Arnold, Farley, Robinson, Clinton, South Texas, San Onofre, Cook, Comanche Peak, Yankee Rowe, Maine Yankee, Quad Cities, Humboldt Bay, La Crosse, Big Rock Point, Rancho Seco, Zion, Midland, Bellefonte, Fort Calhoun, FitzPatrick, McGuire, LaSalle, Fort Saint Vrain, Shoreham, Satsop, Trojan, Atlantic Nuclear Power Plant, Crane  
Issue date: 12/30/1994
From: Grimes B
Office of Nuclear Reactor Regulation
To:
References
IN-94-090, NUDOCS 9412270233
Download: ML031060383 (11)
v • d • e


UNITED STATES

NUCLEAR REGULATORY COMMISSION

OFFICE OF NUCLEAR REACTOR REGULATION

WASHINGTON, D.C. 20555 December 30, 1994 NRC INFORMATION NOTICE 94-90: TRANSIENT RESULTING IN A REACTOR TRIP

AND MULTIPLE SAFETY INJECTION SYSTEM

ACTUATIONS AT SALEM

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 to the events associated with the loss of

circulating water at Salem Nuclear Power Plant, Unit 1, on April 7, 1994, that

led to a reactor trip followed by multiple automatic actuations of the safety

injection system. 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 are not NRC requirements; therefore, no specific action or written

response is required.

Description of Circumstances

On April 7, 1994, at 10:00 a.m., Salem, Unit 1 was in Mode 1 at 73-percent

power. Public Service Electric and Gas Company (the licensee) was operating

the unit at reduced power because river detritus (marsh grass) had fouled the

circulating water intake structure causing a reduction in condenser cooling

efficiency. In response, the operators decreased the power level of Unit 1 to

approximately 60 percent because of an increase in condenser back pressure

caused by grass fouling of the traveling screens at the intake structure. In

response to an impending loss of circulating water, the operators began

reducing load by 1 percent per minute. However, in rapid succession, several

of the Unit 1 traveling screens became clogged with grass, causing the

associated pumps to trip, until only 1 circulating water pump remained

running. As the pumps were lost from service, operators increased the rate of

the load reduction to 8 percent per minute.

Operators attempted to reduce unit load as rapidly as reactor power was being

decreased by insertion of control rods and addition of boron. The effort

caused a power mismatch that resulted in a slight, but continuing, increase in

reactor coolant temperature. In response, the nuclear shift supervisor

directed the operator controlling reactor power to go to the electrical

distribution control panel and shift plant electrical loads to offsite power

sources. Although operators believed that the plant was stable, they failed

P/)p rz dD. Soqo

Woee 7W/2 30

9412270233 I

&lcj-r u1 I/S/95

KJ~

IN 94-90

December 30, 1994 to recognize that reactor power was still decreasing because of the delayed

effect of a previous addition of boron. This caused a reversal of the power

mismatch and resulted in reactor coolant system (RCS) temperature decreasing

to below the minimum temperature at which criticality is allowed. The

operators attempted to restore RCS temperature by increasing reactor power

from approximately 7 percent to 25 percent. However, since power had been

below 10 percent, the power range "high neutron flux-low setpoint" trip had

been automatically reinstated, establishing 25-percent reactor power as the

trip setpoint. When power reached 25 percent, the reactor automatically

tripped.

Almost immediately, train 'A" of the safety injection (SI) logic actuated on a

high steam flow signal coincident with low RCS temperature. (Later

investigation revealed that the high steam flow signal was actually the result

of a pressure wave created in the main steam lines when the turbine stop

valves closed as a result of the turbine trip). In response to the reactor

trip and safety injection, the operators entered the plant emergency operating

procedures. The SI logic did not reposition all necessary components to the

expected, post-actuation position because the initiating signal was so short.

The operators manually repositioned the affected components to their proper

positions. At 11:00 a.m., the licensee declared an unusual event based on a

"manual or automatic emergency core cooling system actuation with a discharge

to the vessel." When the operators took action to reset the SI logic, they

discovered that train "B" of the SI logic had not actuated, indicating an

apparent logic error.

As the operators were attempting to stabilize the plant, the RCS continued to

heat up because of reactor decay heat combined with reactor coolant pump heat.

Steam generator pressure increased but was not automatically relieved by the

steam generator atmospheric relief valves because of a pre-existing condition

that prevented the proper automatic operation of the valves. Concurrently, because of RCS heatup and the volume of water added by the safety injection, the pressurizer filled to a solid condition, and the pressurizer power- operated relief valves cycled several hundred times to control RCS pressure.

A short time later, steam generator pressure increased in the "11" and "13"

steam generators to the safety valve lift setpoint. The opening of a safety

valve caused a rapid cooldown and depressurization of the RCS that was

magnified by the solid condition of the system. RCS pressure rapidly reached

the automatic SI setpoint of 1755 psig, and since train "B" of the SI logic

had remained armed, a second automatic SI actuation occurred. At about the

same time, operators manually initiated safety injection in response to the

rapidly decreasing RCS pressure. After the second safety injection, operators

remained in the emergency operating procedures, and continued their attempts

to stabilize plant conditions. The pressurizer relief tank rupture disk

actuated because of increasing tank pressure caused by the volume of RCS water

relieved to the pressurizer relief tank from the pressurizer power-operated

relief valves.

IN 94-90

December 30, 1994 The operators controlled plant pressure using the charging and letdown

provisions of the chemical and volume control system because normal RCS

pressure control was not available due to the solid condition of the system.

At 1:16 p.m., licensee management declared an alert to ensure activation of

the Salem Technical Support Center to provide the Salem operators with

additional technical assistance to support cooldown of the plant.

Accordingly, the Technical Support Center was fully staffed.

At 3:11 p.m., the operators established a steam bubble in the pressurizer

using pressurizer heaters. At 4:30 p.m., operators restored pressurizer level

to the normal band and returned level control to automatic. They subsequently

exited the emergency operating procedures and used the integrated operating

procedures to cool the plant down to Mode 4 (Hot Shutdown), which was achieved

at 1:06 a.m. on April 8, and then to Mode 5 (Cold Shutdown), which was

achieved at 11:24 a.m. on the same day.

Discussion

On April 8, 1994, the NRC dispatched an Augmented Inspection Team to

investigate the event. The results of that inspection were documented in NRC

Inspection Report 50-272/94-80, dated June 24, 1994. Although several issues

emerged from the NRC investigation of this event, three specific aspects are

of particular concern. These aspects are discussed below.

Solid State Protection System Logic Mismatch: During the first SI actuation, the "A" and "B" logic trains of the solid state protection system were

mismatched. Train "A" sensed and responded to conditions representative of a

steam line break accident, namely a low RCS temperature coincident with a high

steam line flow. Although these conditions were real indications, the RCS low

temperature was due to operator error and the high steam flow was a transient

signal induced by a pressure wave resulting from the closure of the turbine

stop and control valves. This transient signal had a duration of about 30

milliseconds, which system response testing later showed was sufficient for

certain portions of the "A" logic to respond, but of insufficient duration for

the "B" logic to respond. The logic mismatch appears to be a result of the

variations in response sensitivity to the steam flow input relays. The

licensee modified the design to require a longer signal duration before the

logic is actuated so that such transient signals would not result in an

undesired safety injection.

Nuclear Instrument Rod Shadowing: Before the initial reactor trip, when the

operators were raising reactor power to restore RCS temperature, the

intermediate range and power range nuclear instruments were not in agreement

with respect to indicated power. The intermediate range detectors were

"trailing" the power range by about 5 to 10 percent. This led to a condition

in which the reactor was tripped at the 25-percent power range setpoint before

the rod block signal was received from the intermediate range detectors at

20-percent power. The discrepancy between the power and intermediate range

nuclear instruments was apparently due to "rod shadowing."

IN 94-90

December 30, 1994 The combination of the cool RCS and the rod pattern resulting from the down

power maneuver shielded the intermediate range detectors, causing the

instruments to indicate a lower power than the power range detectors.

Although this bias was within an acceptable envelope for detector operability, the response of the instruments was not initially understood. This led to

concern that the nuclear instruments were not properly operating.

Control Room Command and Control: Before the initial reactor trip, shift

management directed staff to support actions necessary to restore circulating

water. The Shift Technical Advisor, a senior reactor operator assigned to the

work control station, was directed to assist in the restoration of affected

equipment. The extra duty reactor operator was directed to assist at the

intake structure. The senior shift supervisor was initially in the control

room area, but subsequently left to go to the turbine building. This

deployment of licensed operators led to minimal staffing of the control room

at the onset of the transient.

During this time, the operators were preparing to take the unit turbine off

line, and the reactor controls operator was directed by the shift supervisor

to initiate actions to transfer plant electrical loads. This led to the

reactor controls watch station not being staffed during a reactivity change.

The RCS began to cool as a result of a slight power mismatch between the

reactor and the turbine. When the shift supervisor first discovered this

mismatch, he began to raise reactor power to restore temperature, which led to

a momentary loss of the command oversight function. He subsequently

recognized the need to maintain an overall command posture and stopped

withdrawing control rods. However, he continued to allow the reactor controls

operator to swap the electrical loads and the RCS temperature continued to

decrease. When the reactor controls operator completed the electrical plant

realignment, the shift supervisor then directed him to raise reactor power to

restore RCS temperature. The shift supervisor did not discuss the fact that

he had manipulated the control rods with the reactor controls operator, and

his direction to the relatively inexperienced operator lacked specificity (how

far or how fast to raise power). The operator subsequently raised reactor

power until the 25-percent power trip was reached.

Related Generic Communications

Power-Operated Relief Valves," August 4, 1994.

This information notice discusses cracking of plug material, severe wear

of plugs and cages, and a problem with the misalignment and galling of a

stem in the power-operated relief valves discovered as a result of valve

inspection subsequent to the April 7, 1994, event.

Coolant System," May 24, 1994.

This information notice discusses lack of operator awareness of an

accumulation of nitrogen in the reactor vessel head during cooldown and

depressurization of the RCS subsequent to the April 7, 1994, event.

IN 94-90

December 30, 1994 This information notice requires no specific action or written response. If

you have any questions about the information in this notice, please contact

the technical contact listed below or the appropriate Office of Nuclear

Reactor Regulation (NRR) project manager.

rian K. Grimes, Director

Division of Project Support

Office of Nuclear Reactor Regulation

Technical contacts: Robert J. Summers, RI

(609) 935-3850

Eric J. Benner, NRR

(301) 504-1171 Attachment:

List of Recently Issued NRC Information Notices

hiW 54-r 11J cGi.,7-"4

K>

Attachment

IN 94-90

December 30, 1994 LIST OF RECENTLY ISSUED

NRC INFORMATION NOTICES

Information Date of

Notice No. Subject Issuance Issued to

94-89 Equipment Failures at 12/28/94 All U.S. Nuclear Regulatory

Irradiator Facilities Commission irradiator

licensees.

94-88 Inservice Inspection 12/23/94 All holders of OLs or CPs

Deficiencies Result in for pressurized water

Severely Degraded Steam reactors.

Generator Tubes

94-87 Unanticipated Crack in a 12/22/94 All holders of OLs or CPs

Particular Heat of for nuclear power reactors.

Alloy 600 Used for

Westinghouse Mechanical

Plugs for Steam Generator

Tubes

94-86 Legal Actions Against 12/22/94 All holders of OLs or CPs

Thermal Science, Inc., for nuclear power reactors.

Manufacturer of Thermo-Lag

94-85 Problems with the 12/21/94 All holders of OLs or CPs

Latching Mechanism for nuclear power reactors.

in Potter and Brumfield

R1O-E3286-2 Relays

94-40, Failure of a Rod Control 12/15/94 All holders of OLs or CPs

Supp. 1 Cluster Assembly to Fully for nuclear power reactors.

Insert Following a Reactor

Trip at Braidwood Unit 2

94-84 Air Entrainment in Terry 12/02/94 All holders of OLs or CPs

Turbine Lubricating Oil for nuclear power reactors.

System

89-25, Unauthorized Transfer of 12/07/94 All fuel cycle and material

Rev. 1 Ownership or Control of licensees.

Licensed Activities

94-83 Reactor Trip Followed by 12/06/94 All holders of OLs or CPs

Unexpected Events for nuclear power reactors.

OL = Operating License

CP = Construction Permit

IN 94-XX

November xx, 1994 This information notice requires no specific action or written response. If

you have any questions about the information in this notice, please contact

the technical contact listed below or the appropriate Office of Nuclear

Reactor Regulation (NRR) project manager.

Brian K. Grimes, Director

Division of Project Support

Office of Nuclear Reactor Regulation

Technical contacts: Robert J. Summers

(609) 935-3850

Eric J. Benner

(301) 504-1171 Attachment: List of Recently Issued NRC Information Notices

E-mailed to John White and Robert Summers of Region I for review on 10/21/94.

OFC OECB:DOPS PUB:ADM SC/OECB:DOPS BC/SRXB:DSSA

NAME EBenner Tech Ed* EGoodwin* RJones*

DATE 11/14/94 110/17/94

.-

110/24/94

.I.

,10/26/94 OFC OECB:DOPS BC/OECB:DOPS D/DOPS

NAME RKiessel* AChaffee* BGrime

DATE 11/02/94 11/16/94 / /94

[OFFICIAL RECORD COPY] DOCUMENT NAME: S:\DOP S SEC\SALEM.IN

IN 94-XX

November xx, 1994 This information notice requires no specific action or written response. If

you have any questions about the information in this notice, please contact

the technical contact listed below or the appropriate Office of Nuclear

Reactor Regulation (NRR) project manager.

I

Brian K. Grimes, Director

Division of Projects Support

Office of Nuclear Reactor Regulation

Technical contact: Robert J. Summers

(609) 935-3850

Eric J. Benner

(301) 504-1171 Attachment:

1. List of Recently Issued NRC Information Notices

E-mailed to John White and Robert Summers of Region I for review on 10/21/94.

OFC lOECB:DOPS PUB:ADM SC/OECB:DOPS BC/SRXB:DSSA

NAME EBenner Tech Ed* EGoodwin* RJones*

DATE 111/14/94 10/17/94 10/24/94 110/26/94 _ j

OFC OECB:DOPS BC/OLCB:DOPS D/DOPS

NAME RKiessel* e BGrimes

DATE 111/02/94 1/ 1 n/94J / /94 r I

-- -- - -I maAEI- II AIA&Ir P - %

LU[ICLIAL KtLUKU LUfYJ MUUUMtN I NAMLI; U ; \ Cd JB1\SALEM.IN

K>j

IN 94-XX

November xx, 1994 This information notice requires no specific action or written response. If

you have any questions about the information in this notice, please contact

the technical contact listed below or the appropriate Office of Nuclear

Reactor Regulation (NRR) project manager.

Brian K. Grimes, Director

Division of Projects Support

Office of Nuclear Reactor Regulation

Technical contact: Eric J. Benner

(301) 504-1171 Attachment:

1. List of Recently Issued NRC Information Notices

E-mailed to John White and Robert Summers of Region I for review on 10/21/94.

OFC OECB:DOPS l PUB:ADM SC/OECB:DOPS BC/SRXB:DSSA

NAME EBenner Tech Ed* EGoodwin* RJones*

DATE 11 /c2/94 10/17/94 j10/24/94 110/26/94 1 T Ifi-

____-1 nrC t

gFErpfnPS

- . , RC/OECB:DOPS -- --. D/DOPS

NAME RKi tsel A AChaffee BGrimes

DATE _V)//I94 I / /94 / /94

..- fr.r

-1

[OFFICIAL RECORD COPY] UUUvlMMI NAMt: U : Xr JB1\SALEM.IN

v)

IN 94-XX

November, xx, 1994 shift supervisor was initially in the control room area, but subsequently left

to go to the turbine building. This deployment of licensed staffing led to

minimal staffing of the control room at the onset of the transient. During this

time, the operators were preparing to take the unit turbine off-line, and the

reactor controls operator was directed by the shift supervisor to initiate

actions to transfer plant electrical loads. This led to the reactor controls

watch station not being manned during a reactivity change. The RCS began to cool

as a result of a slight power mismatch between the reactor and the turbine. When

first identified by the shift supervisor, he began to raise reactor power to

restore temperature, which led to a momentary loss of the command function. The

shift supervisor subsequently recognized the need to maintain an overall command

posture and stopped withdrawing control rods. However, he continued to allow the

reactor controls operator to swap the electrical loads and RCS temperature

continued to degrade. When the reactor controls operator completed the

electrical plant realignment, the shift supervisor then directed him to raise

reactor power to restore RCS temperature. This direction was not specific as to

how far to raise power, which, coupled with the operator's inexperience, led to

the operator raising reactor power until reaching the 25 percent power trip.

Related Generic Communications

- NRC IN 94-55, 'Problems with Copes-Vulcan Pressurizer Power-Operated

Relief Valves,' August 4, 1994.

- NRC IN 94-36, Undetected Accumulation of Gas in Reactor Coolant

System," May 24, 1994.

This information notice requires no specific action or written response. Ifyou

have any questions about the information in this notice, please contact the

technical contact listed below or the appropriate Office of Nuclear Reactor

Regulation (NRR) project manager.

Brian K. Grimes, Director

Division of Projects Support

Office of Nuclear Reactor Regulation

Technical contact: Eric J. Benner

(301) 504-1171 Attachments:

1. List of Recently Issued NRC Information Notices

E-mailed to John White and Robert Summers of Region I for review on l1/19/94.

OFC OECB:DOPS PUB:ADM lSC/OECB:DOPS SRXB:DSSV

NAME EBenner Wi X Tech Ed A M c iiEGoodwi n 1iJ I

DATE eA //gV/94 10/rt1/94 /94

- 11 OFC I BC/SRXB:DSSin I BC/OECB:DOPS I D/DOPS I

NAME RJoneb %I/ IAChaffee BGrimes

DATE g 94 /- -..Y / /94 O / /94 A E ., A .

[O. I A - - E

[OFFICIAL RECORD COPYJ DOCUMENT NAME: U:XLJBl\SALtM.IN

W

IN 94-90

December 30, 1994 This information notice requires no specific action or written response. If

you have any questions about the information in this notice, please contact

the technical contact listed below or the appropriate Office of Nuclear

Reactor Regulation (NRR) project manager.

WOW 1gd. le-by

Kdo

L Omet

Brian K. Grimes, Director

Division of Project Support

Office of Nuclear Reactor Regulation

Technical contacts: Robert J. Summers, RI

(609) 935-3850

Eric J. Benner, NRR

(301) 504-1171 Attachment:

List of Recently Issued NRC Information Notices

DOCUMENT NAME: 94-90. IN

  • See previous concurrences

E-mailed to John White and Robert Summers of Region I for review on 10/21/94.

OFC OECB:DOPS PUB:ADM SC/OECB:DOPS BC/SRXB:DSSA

NAME EBenner Tech Ed* EGoodwin* RJones*

DATE 111/14/94 1 10/17/94 10/24/94 _ /710/26/94 OFC OECB:DOPS BC/OECB:DOPS

l~ - IF -

-e- -

NAME RKiessel* AChaffee*

DATE 11/02/94 11/16/94 j12/Z7/94

[OFFICIAL RECORD COPY]


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