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{{#Wiki_filter:UNITED STATES P/-3YNUCLEAR REGULATORY COMMISSIONOFFICE OF NUCLEAR REACTOR REGULATIONWASHINGTON, D.C. 20555May 24, 1994NRC INFORMATION NOTICE 94-36: UNDETECTED ACCUMULATION OF GAS IN REACTORCOOLANT SYSTEM
{{#Wiki_filter:UNITED STATES P/-3Y NUCLEAR REGULATORY
 
COMMISSION
 
===OFFICE OF NUCLEAR REACTOR REGULATION===
WASHINGTON, D.C. 20555 May 24, 1994 NRC INFORMATION
 
NOTICE 94-36: UNDETECTED
 
ACCUMULATION
 
OF GAS IN REACTOR COOLANT SYSTEM


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


==Purpose==
==Purpose==
The U.S. Nuclear Regulatory Commission (NRC) is issuing this informationnotice to alert addressees to problems that could result from unrecognizedevolution and accumulation of gas in reactor coolant system high points. Itis expected that recipients will review this information for applicability totheir facilities and consider actions, as appropriate, to avoid similarproblems. However, suggestions contained in this information notice are notNRC requirements; therefore, no specific action or written response isrequired.
The U.S. Nuclear Regulatory
 
Commission (NRC) is issuing this information
 
notice to alert addressees
 
to problems that could result from unrecognized
 
evolution
 
and accumulation
 
of gas in reactor coolant system high points. It is expected that recipients
 
will review this 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
 
Sequoyah Unit I had been shut down in March 1993. In early September
 
1993, after the unit had been refueled, the reactor vessel was reassembled
 
and the reactor coolant system was degassed, filled, and vented. The reactor coolant system was then depressurized
 
to atmospheric
 
pressure.
 
One pressurizer
 
power-operated relief valve (PORV) was open and the reactor coolant system average temperature
 
was being maintained
 
at approximately
 
49C [120'F]. Nitrogen cover gas was being supplied to the volume control tank at approximately
 
239 kPa [20 psig] and reactor coolant was being circulated
 
by the charging system and the residual heat removal (RHR) system. The reactor vessel level indication
 
system (RVLIS) was functional
 
for a significant
 
portion of the event. Before this event, instrument
 
maintenance
 
stickers were placed on the RVLIS indicators
 
for other maintenance
 
work. Although the RVLIS information
 
was available, the operators
 
were not monitoring
 
this information
 
because it was not procedurally
 
required to be used in shutdown modes of operation.
 
Reactor coolant system inventory
 
was being monitored
 
using pressurizer
 
cold calibration
 
level indications.
 
On December 17, 1993, the operators
 
began to pressurize
 
the containment
 
to 191 kPa [13 psig] in order to perform a containment
 
integrated
 
leak rate test.As containment
 
pressure increased, the operators
 
noticed a decrease in pressurizer
 
water level and, over a period of time, added approximately
 
31,400 liters [8,300 gallons] of water to maintain the pressurizer
 
level. Licensee personnel
 
evaluated
 
this situation
 
and recognized
 
that gas was accumulating
 
in the reactor coolant system. However, they failed to recognize
 
the magnitude 9405190137 po\ fit JE ote qq-f3tn 9t1S EsoI'I'
:..~ -IN 94-36 May 24, 1994 or cause of the problem. Three days later, as the containment
 
was being depressurized
 
upon completion
 
of the containment
 
leak test, the operators noted that approximately
 
the same amount of water had to be removed from the reactor coolant system to maintain the level. On December 21, 1993, on the basis of operators'
observations
 
of the changing coolant system Inventory during the containment
 
leak test, the reactor vessel head was vented. It was subsequently
 
vented several times to maintain appropriate
 
reactor vessel inventory
 
based on RYLIS information.
 
The reactor vessel gas voiding conditions
 
went undetected
 
from early September
 
1993, when the reactor coolant system was verified to be filled, until December 21, 1993, when the reactor head was vented.The gas evolution
 
resulted from the temperature
 
in the volume control tank being much lower than that normally expected. (This lower temperature
 
was due to unusually
 
low component
 
cooling water temperatures
 
and to a maintenance
 
problem with a cooling water valve that resulted in the reduction
 
of the heat sink temperature
 
in the letdown heat exchanger.)
 
===The lower temperatures===
increased
 
the solubility
 
of gas in the volume control tank water so that more gas was dissolved
 
in the water. This gas evolved when the water was transferred
 
to the reactor coolant system by the charging system and heated up in the reactor vessel.Further details concerning
 
this event are in NRC Inspection
 
Report No. 50-327;50-328/94-04.
 
Discussion
 
The licensee completed
 
a final evaluation
 
in January 1994 and determined
 
that during this event the reactor vessel water level had decreased
 
to slightly below the top of the hot leg, and that the steam generator
 
tubes were nearly empty. The reactor coolant system inventory
 
was being monitored
 
solely on the basis of pressurizer
 
level, which was not indicative
 
of the reactor vessel and steam generator
 
levels. Calculations
 
by the licensee indicated
 
that an equilibrium
 
had been reached during the event so that the water level was approximately
 
1.6 meters [5.25 feet] above the top of the core. Any additional
 
gas evolved in the reactor vessel would be expected to be vented through the hot leg and surge line to the pressurizer
 
and out through the open pressurizer
 
PORV.The reactor water level at which equilibrium
 
was established
 
at Sequoyah was sufficiently
 
high so as not to interfere
 
with reactor coolant flow through the RHR cooling system. However, at other plants, the equilibrium
 
level, which is related to pressurizer
 
surge line geometry and RHR suction line location, might be such that a similar event could interfere
 
with shutdown cooling.Another potential
 
safety concern is related to the capability
 
of the steam generators
 
to transfer heat from the reactor coolant to secondary
 
coolant. In the equilibrium
 
condition
 
at Sequoyah, the steam generator
 
tubes were almost empty during at least a portion of the duration of this event. During this
 
IN 94-36--JMay 24, 1994 period, the steam generators
 
were assumed to be available
 
as an alternate means for shutdown cooling. It is not clear that cooling through the steam generators
 
could have been established, if needed, especially
 
because the plant operators
 
were unaware that the tubes were empty.Several factors involving
 
licensee performance
 
contributed
 
to the delay in the identification
 
and evaluation
 
of this event. They included (1) lack of consideration
 
on the part of licensee personnel
 
with respect to compression
 
of gas in the system caused by containment
 
pressure transmitted
 
to the reactor coolant system water through the open pressurizer
 
PORV; (2) misunderstanding
 
by the operators
 
about the operability
 
of RVLIS; (3) failure to stop the containment
 
leak test when water level changes were first noted so that the situation
 
could have been adequately
 
evaluated;
(4) an apparent lack of thorough evaluation
 
of previously
 
published
 
information
 
on similar events.The event discussed
 
in this information
 
notice highlights
 
the potential
 
for gas evolution
 
and accumulation
 
in the reactor coolant system in locations
 
and quantities
 
that may not be evident to operators.
 
Changes in temperature
 
and pressure can have significant
 
effects on the solubility
 
of gas in water, especially
 
at or near atmospheric
 
pressure conditions.
 
During cold shutdown, this phenomenon
 
can permit significant
 
quantities
 
of cover gas to be dissolved in lower-temperature, higher-pressure
 
volumes such as the volume control tank and to evolve into a large gas bubble in the reactor vessel (a lower-pressure, higher-temperature
 
area). This phenomenon
 
can occur without a sudden change in pressurizer
 
level, which is the indicator
 
normally used by the operators
 
to monitor water inventory.
 
Use of available
 
instrumentation
 
in shutdown modes to monitor reactor vessel water level can provide detection
 
of unexpected
 
system conditions
 
when reduced vessel inventory
 
is not planned as well as in reduced inventory
 
evolutions.
 
On April 12, 1994, a similar gas accumulation
 
event was identified
 
at the Salem Generating
 
Station (Unit 1) shortly after it entered Mode 5 (cold shutdown)
operation.
 
Although this occurrence
 
did not involve amounts of gas accumulation
 
as large as in the Sequoyah event, many similarities
 
existed regarding
 
both the process of gas formation
 
and the lack of operator awareness of the abnormal condition.
 
===In both events, reactor vessel level information===
was or could have been made available
 
for prompt identification
 
of the problem.Related Generic Communications
 
* NRC Information
 
Notice 93-12, "Off-Gassing
 
in Auxiliary
 
Feedwater System Raw Water Sources," discusses
 
similar solubility
 
considerations
 
related to air pockets in piping at the McGuire Nuclear Station.* NRC Information
 
Notice 87-46, "Undetected
 
Loss of Reactor Coolant," discusses
 
undetected
 
loss of reactor coolant inventory at North Anna Unit 1 resulting
 
from inadequate
 
use of available indications
 
and failure to perform mass inventory
 
balances.
 
-\ > <_IN 94-36 May 24, 1994 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
 
Of ice of Nuclear Reactor Regulation (NRR) project manager.Brian K. Grimes, Director Division of Operating
 
===Reactor Support Office of Nuclear Reactor Regulation===
Technical
 
contacts:
R. Benedict, NRR (301) 504-1157 S. M. Shaeffer, RII (615) 842-8001 Attachment:
List of Recently Issued NRC Information
 
Notices
 
===I At,.thment===
IN 94-36 May 24, 1994 LIST OF RECENTLY ISSUED NRC INFORMATION
 
NOTICES Information
 
Date of Notice No. Subject Issuance Issued to 91-81, Supp. 1 94-35 94-34 94-33 93-53, Supp. 1 94-32 94-31 90-68, Supp. 1 94-30 Switchyard
 
Problems that Contribute
 
to Loss of Offsite Power NIOSH Respirator
 
User Notices, "Inadvertent
 
Separation
 
of the Mask-Mounted Regulator (MMR)from the Facepiece
 
on the Mine Safety Appliances (MSA)Company MMR Self-Contained
 
Breathing
 
Apparatus (SCBA)and Status Update Thermo-Lag
 
330-660 Flexi-Blanket
 
Ampacity Derating Concerns Capacitor
 
Failures in Westinghouse
 
Eagle 21 Plant Protection
 
Systems Effect of Hurricane Andrew on Turkey Point Nuclear Generating
 
Station and Lessons Learned Revised Seismic Hazard Estimates Potential
 
Failure of Wilco, Lexan-Type
 
HN-4-L Fire Hose Nozzles Stress Corrosion
 
Cracking of Reactor Coolant Pump Bolts Leaking Shutdown Cooling Isolation
 
Valves at Cooper Nuclear Station 05/19/94 05/16/94 05/13/94 05/09/94 04/29/94 04/29/94 04/14/94 04/14/94 04/12/94 All holders of OLs or CPs for nuclear power reactors.All holders of OLs or CPs for nuclear power reactors, and all licensed fuel facilities.
 
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 holders of 01 or CPs for pressurized
 
water reactors.All holders of OLs or CPs for nuclear power reactors.OL -Operating
 
License CP -Construction
 
Permit
 
IN 94-xx May 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 one of the technical
 
contacts listed below or the appropriate
 
Office of Nuclear Reactor Regulation (NRR) project manager.Brian K. Grimes, Director Division of Operating
 
===Reactor Support Office of Nuclear Reactor Regulation===
Technical
 
contacts: R. Benedict, NRR (301) 504-1157 S. M. Shaeffer, R11 (615) 842-8001 Attachment:
List of Recently Issued NRC Information
 
Notices*See Dnrvinim- concurrence
 
---- wBw _. _ .-1 _._OFFICE *OEAB:DORS
 
*DRP:RII *OGCB:DORS
 
*SC/DRP:RII
 
*TECH ED NAME RBenedict
 
SMShaeffer
 
PCWen MLesser MFMejaclDATE 05/04/L94
05/05/94 05/05/94 05/05/94 05/05/94[*AC/SRXB:DSSA
 
*AD/DSSA *C/OEAB:DORS
 
*AC/OGCB:DORS
 
D/DORS TECollins
 
MVirgilio
 
AChaffee AJKugler BKGrimes 05/06/94 05/09/94 05/09/94 05.12/94 / /94 DOCUMENT NAME: SLQGAbIN.KV1 NOTE: The PMs for Sequoyah (D. LaBarge) and Salem (J.informed of the development
 
of this information
 
reviewed the draft information
 
notice.Stone) have been notice and they have Peter Wen, 5/10/94 IN 94-xx May 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 Operating
 
===Reactor Support Office of Nuclear Reactor Regulation===
Technical
 
Contacts: R. Benedict, NRR (301) 504-1157 S. M. Shaeffer, RI!(615) 842-8001 Attachment:
List of Recently Issued NRC Information
 
Notices*See previous concurrence
 
OFFICE *OEAB:DORS
 
*DRP:RII *OGCB:DORS
 
*SC/DRP:RII
 
*TECH ED NAME RBenedict
 
SMShaeffer
 
PCWen MLesser MFMejac DATE 05/04/94 05/05/94 05/05/94 05/05/94 05/05/94*AC/SRXB:DSSA
 
*AD/DSSA *C/OEAB:DORS
 
*AC/OGCB:DORS
 
D/DORS TECollins
 
8EXI MVirgilio
 
I AChaffee AJKugler BKGrimes 05/06/94 1 05/09/94 05/09/94 05/12/94 / /94 nnlflMFNT
 
IAMr. eCnveCTit
 
niti.-- -- I ia11 I EAdIL* .JLA(Un4.1 n .* r A NOTE: The PMs for Sequoyah (D. LaBarge) and Salem (J.informed of the development
 
of this information
 
reviewed the draft information
 
notice.Stone) have been notice and they have Peter Wen, 5/10/94 IN 94-xx May 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 Operating
 
===Reactor Support Office of Nuclear Reactor Regulation===
Technical
 
Contacts: R. Benedict, NRR (301) 504-1157 S. M. Shaeffer, R11 (615) 842-8001 Attachment:
List of Recently Issued NRC Information
 
===Notices See previous concurrence===
OFFICE l *OEAB:DORS
 
*DRP:RII *OGCB:DORS
 
l *SC/DRP:RII
 
*TECH ED NAME } RBenedict
 
SMShaeffer
 
PCWen MLesser MFMejac DATE 1 05/04/94 1_05/05/94
1 05/05/94 _ 05/05/94 1 05/05/94*AC/SRXB:DSSA
 
*AD/DSSA j *C/OEAB:DORS
 
AC/OGCB:DORS
 
D/DORS TECollins
 
MVirgilio
 
AChaffee AJKugler i(: BKGrimes 05/06/94 = 05/09/94 05/09/94 5/1V94 / /94 DOCUMENT NAME: SEQGASIN.RV1 NOTE: The PMs for Sequoyah (D. LaBarge) and Salem (J.informed of the development
 
of this information
 
reviewed the draft information
 
notice.Stone) have been notice and they have Peter Wen, 5/10/94 IN 94-xx May xx, 1994 This information
 
notice requires no specific action or writttten
 
response.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.If Brian K. Grimes, Director Division of Operating
 
===Reactor Support Office of Nuclear Reactor Regulation===
Technical
 
Contacts: R. Benedict, NRR (301) 504-1157 S. M. Shaeffer, RII (615) 842-8001 Attachment:
List of Recently Issued NRC Information
 
Notices OFFICE IOEABDOR5 DRP:RIIpcyJ
 
OGCB_ _ _ SC/DRP:RI
 
TECH ED NAME Benedict 'MShaeffer
 
PCWen Lesser DATE </A/94 5 /5/94 5 / 94/94 5//94 5 / 5/94 AC/SRXB:DSSA , AD/DSSA j C/OEAB:DORS
 
AC/OGCB:DORS
 
D/DORS TEColli MVirgil ' A2 fe AJKugler BKGrimes_____94 /$\/94 /947/94 94 / /94 UULUMtN I NAML: x 01 I J//q btbAbI1 N.KV1 jp'A4Mi: THE R& FR FoY(AH (-. LAMRPE) Azb 6MPA (j. )ROeia^ SoF'E Deospwt oF Ttts um. waIce ARD'NW ME .F) T"E JPV O D0e bWf ^ .&4-vhiw S/o/oA4.
 
IN 94-36 May 24, 1994 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
 
Office of Nuclear Reactor Regulation (NRR) project manager.orig /s/'d by BKGrimes Brian K. Grimes, Director Division of Operating
 
===Reactor Support Office of Nuclear Reactor Regulation===
Technical
 
contacts: R. Benedict, NRR (301) 504-1157 S. M. Shaeffer, R11 (615) 842-8001 Attachment:
List of Recently Issued NRC Information
 
Notices*See Previous concurrence
 
E OFFICE *OEAB:DORS
 
*DRP:RII *OGCB:DORS
 
*SC/DRP:RII
 
*TECH ED NAME RBenedict
 
SMShaeffer
 
PCWen MLesser MFMejac DATE j05/04/94
05/05/94 05/05/94 05/05/94 05/05/94l*AC/SRXB:DSSA
 
*AD/DSSA 5*C/OEAB:DORS
 
*AC/OGCB:DO


==Description of Circumstances==
RS*TECollins
Sequoyah Unit I had been shut down in March 1993. In early September 1993,after the unit had been refueled, the reactor vessel was reassembled and thereactor coolant system was degassed, filled, and vented. The reactor coolantsystem was then depressurized to atmospheric pressure. One pressurizer power-operated relief valve (PORV) was open and the reactor coolant system averagetemperature was being maintained at approximately 49C [120'F]. Nitrogencover gas was being supplied to the volume control tank at approximately239 kPa [20 psig] and reactor coolant was being circulated by the chargingsystem and the residual heat removal (RHR) system. The reactor vessel levelindication system (RVLIS) was functional for a significant portion of theevent. Before this event, instrument maintenance stickers were placed on theRVLIS indicators for other maintenance work. Although the RVLIS informationwas available, the operators were not monitoring this information because itwas not procedurally required to be used in shutdown modes of operation.Reactor coolant system inventory was being monitored using pressurizer coldcalibration level indications.On December 17, 1993, the operators began to pressurize the containment to191 kPa [13 psig] in order to perform a containment integrated leak rate test.As containment pressure increased, the operators noticed a decrease inpressurizer water level and, over a period of time, added approximately 31,400liters [8,300 gallons] of water to maintain the pressurizer level. Licenseepersonnel evaluated this situation and recognized that gas was accumulating inthe reactor coolant system. However, they failed to recognize the magnitude9405190137 po\ fit JE ote qq-f3tn 9t1S EsoI'I'
:..~ -IN 94-36May 24, 1994 or cause of the problem. Three days later, as the containment was beingdepressurized upon completion of the containment leak test, the operatorsnoted that approximately the same amount of water had to be removed from thereactor coolant system to maintain the level. On December 21, 1993, on thebasis of operators' observations of the changing coolant system Inventoryduring the containment leak test, the reactor vessel head was vented. It wassubsequently vented several times to maintain appropriate reactor vesselinventory based on RYLIS information. The reactor vessel gas voidingconditions went undetected from early September 1993, when the reactor coolantsystem was verified to be filled, until December 21, 1993, when the reactorhead was vented.The gas evolution resulted from the temperature in the volume control tankbeing much lower than that normally expected. (This lower temperature was dueto unusually low component cooling water temperatures and to a maintenanceproblem with a cooling water valve that resulted in the reduction of the heatsink temperature in the letdown heat exchanger.) The lower temperaturesincreased the solubility of gas in the volume control tank water so that moregas was dissolved in the water. This gas evolved when the water wastransferred to the reactor coolant system by the charging system and heated upin the reactor vessel.Further details concerning this event are in NRC Inspection Report No. 50-327;50-328/94-04.DiscussionThe licensee completed a final evaluation in January 1994 and determined thatduring this event the reactor vessel water level had decreased to slightlybelow the top of the hot leg, and that the steam generator tubes were nearlyempty. The reactor coolant system inventory was being monitored solely on thebasis of pressurizer level, which was not indicative of the reactor vessel andsteam generator levels. Calculations by the licensee indicated that anequilibrium had been reached during the event so that the water level wasapproximately 1.6 meters [5.25 feet] above the top of the core. Anyadditional gas evolved in the reactor vessel would be expected to be ventedthrough the hot leg and surge line to the pressurizer and out through the openpressurizer PORV.The reactor water level at which equilibrium was established at Sequoyah wassufficiently high so as not to interfere with reactor coolant flow through theRHR cooling system. However, at other plants, the equilibrium level, which isrelated to pressurizer surge line geometry and RHR suction line location,might be such that a similar event could interfere with shutdown cooling.Another potential safety concern is related to the capability of the steamgenerators to transfer heat from the reactor coolant to secondary coolant. Inthe equilibrium condition at Sequoyah, the steam generator tubes were almostempty during at least a portion of the duration of this event. During this


IN 94-36--JMay 24, 1994 period, the steam generators were assumed to be available as an alternatemeans for shutdown cooling. It is not clear that cooling through the steamgenerators could have been established, if needed, especially because theplant operators were unaware that the tubes were empty.Several factors involving licensee performance contributed to the delay in theidentification and evaluation of this event. They included (1) lack ofconsideration on the part of licensee personnel with respect to compression ofgas in the system caused by containment pressure transmitted to the reactorcoolant system water through the open pressurizer PORV; (2) misunderstandingby the operators about the operability of RVLIS; (3) failure to stop thecontainment leak test when water level changes were first noted so that thesituation could have been adequately evaluated; (4) an apparent lack ofthorough evaluation of previously published information on similar events.The event discussed in this information notice highlights the potential forgas evolution and accumulation in the reactor coolant system in locations andquantities that may not be evident to operators. Changes in temperature andpressure can have significant effects on the solubility of gas in water,especially at or near atmospheric pressure conditions. During cold shutdown,this phenomenon can permit significant quantities of cover gas to be dissolvedin lower-temperature, higher-pressure volumes such as the volume control tankand to evolve into a large gas bubble in the reactor vessel (a lower-pressure,higher-temperature area). This phenomenon can occur without a sudden changein pressurizer level, which is the indicator normally used by the operators tomonitor water inventory. Use of available instrumentation in shutdown modesto monitor reactor vessel water level can provide detection of unexpectedsystem conditions when reduced vessel inventory is not planned as well as inreduced inventory evolutions.On April 12, 1994, a similar gas accumulation event was identified at theSalem Generating Station (Unit 1) shortly after it entered Mode 5 (coldshutdown) operation. Although this occurrence did not involve amounts of gasaccumulation as large as in the Sequoyah event, many similarities existedregarding both the process of gas formation and the lack of operator awarenessof the abnormal condition. In both events, reactor vessel level informationwas or could have been made available for prompt identification of theproblem.Related Generic Communications* NRC Information Notice 93-12, "Off-Gassing in Auxiliary FeedwaterSystem Raw Water Sources," discusses similar solubilityconsiderations related to air pockets in piping at the McGuireNuclear Station.* NRC Information Notice 87-46, "Undetected Loss of ReactorCoolant," discusses undetected loss of reactor coolant inventoryat North Anna Unit 1 resulting from inadequate use of availableindications and failure to perform mass inventory balances.
MVirgilio


-\ > <_IN 94-36May 24, 1994 This information notice requires no specific action or written response. Ifyou have any questions about the information in this notice, please contactone of the technical contacts listed below or the appropriate Of ice ofNuclear Reactor Regulation (NRR) project manager.Brian K. Grimes, DirectorDivision of Operating Reactor SupportOffice of Nuclear Reactor RegulationTechnical contacts: R. Benedict, NRR(301) 504-1157S. M. Shaeffer, RII(615) 842-8001Attachment:List of Recently Issued NRC Information Notices
AChaffee AJKugler Iv _s 05/06/94 05/09/94 i 05/09/94 05/12/4 05//f/94 UuUMtrII NAM t: vq-io. IN NOTE: The PMs for Sequoyah (D. LaBarge) and Salem (J.informed of the development


IAt,.thmentIN 94-36May 24, 1994 LIST OF RECENTLY ISSUEDNRC INFORMATION NOTICESInformation Date ofNotice No. Subject Issuance Issued to91-81,Supp. 194-3594-3494-3393-53,Supp. 194-3294-3190-68,Supp. 194-30Switchyard Problems thatContribute to Loss ofOffsite PowerNIOSH Respirator UserNotices, "InadvertentSeparation of the Mask-Mounted Regulator (MMR)from the Facepiece on theMine Safety Appliances (MSA)Company MMR Self-ContainedBreathing Apparatus (SCBA)and Status UpdateThermo-Lag 330-660Flexi-Blanket AmpacityDerating ConcernsCapacitor Failures inWestinghouse Eagle 21Plant Protection SystemsEffect of HurricaneAndrew on Turkey PointNuclear GeneratingStation and Lessons LearnedRevised Seismic HazardEstimatesPotential Failure ofWilco, Lexan-Type HN-4-LFire Hose NozzlesStress Corrosion Crackingof Reactor Coolant PumpBoltsLeaking Shutdown CoolingIsolation Valves atCooper Nuclear Station05/19/9405/16/9405/13/9405/09/9404/29/9404/29/9404/14/9404/14/9404/12/94All holders of OLs or CPsfor nuclear power reactors.All holders of OLs or CPsfor nuclear power reactors,and all licensed fuelfacilities.All holders of OLs or CPsfor nuclear power reactors.All holders of OLs or CPsfor nuclear power reactors.All holders of OLs or CPsfor nuclear power reactors.All holders of OLs or CPsfor nuclear power reactors.All holders of OLs or CPsfor nuclear power reactors.All holders of 01 or CPsfor pressurized waterreactors.All holders of OLs or CPsfor nuclear power reactors.OL -Operating LicenseCP -Construction Permit
of this information


IN 94-xxMay xx, 1994 This information notice requires no specific action or written response. Ifyou have any questions about the information in this notice, please contactone of the technical contacts listed below or the appropriate Office ofNuclear Reactor Regulation (NRR) project manager.Brian K. Grimes, DirectorDivision of Operating Reactor SupportOffice of Nuclear Reactor RegulationTechnical contacts:R. Benedict, NRR(301) 504-1157S. M. Shaeffer, R11(615) 842-8001Attachment:List of Recently Issued NRC Information Notices*See Dnrvinim- concurrence---- wBw _. _ .-1 _._OFFICE *OEAB:DORS *DRP:RII *OGCB:DORS *SC/DRP:RII *TECH EDNAME RBenedict SMShaeffer PCWen MLesser MFMejaclDATE 05/04/L94 05/05/94 05/05/94 05/05/94 05/05/94[*AC/SRXB:DSSA *AD/DSSA *C/OEAB:DORS *AC/OGCB:DORS D/DORSTECollins MVirgilio AChaffee AJKugler BKGrimes05/06/94 05/09/94 05/09/94 05.12/94 / /94DOCUMENT NAME:SLQGAbIN.KV1NOTE: The PMs for Sequoyah (D. LaBarge) and Salem (J.informed of the development of this informationreviewed the draft information notice.Stone) have beennotice and they havePeter Wen, 5/10/94 IN 94-xxMay xx, 1994 This information notice requires no specific action or written response. Ifyou have any questions about the information in this notice, please contactthe technical contact listed below or the appropriate Office of NuclearReactor Regulation (NRR) project manager.Brian K. Grimes, DirectorDivision of Operating Reactor SupportOffice of Nuclear Reactor RegulationTechnical Contacts:R. Benedict, NRR(301) 504-1157S. M. Shaeffer, RI!(615) 842-8001Attachment:List of Recently Issued NRC Information Notices*See previous concurrenceOFFICE *OEAB:DORS *DRP:RII *OGCB:DORS *SC/DRP:RII *TECH EDNAME RBenedict SMShaeffer PCWen MLesser MFMejacDATE 05/04/94 05/05/94 05/05/94 05/05/94 05/05/94*AC/SRXB:DSSA *AD/DSSA *C/OEAB:DORS *AC/OGCB:DORS D/DORSTECollins 8EXI MVirgilio I AChaffee AJKugler BKGrimes05/06/94 1 05/09/94 05/09/94 05/12/94 / /94nnlflMFNT IAMr. eCnveCTit niti.-- -- I ia11 I EAdIL* .JLA(Un4.1 n .* r ANOTE: The PMs for Sequoyah (D. LaBarge) and Salem (J.informed of the development of this informationreviewed the draft information notice.Stone) have beennotice and they havePeter Wen, 5/10/94 IN 94-xxMay xx, 1994 This information notice requires no specific action or written response. Ifyou have any questions about the information in this notice, please contactthe technical contact listed below or the appropriate Office of NuclearReactor Regulation (NRR) project manager.Brian K. Grimes, DirectorDivision of Operating Reactor SupportOffice of Nuclear Reactor RegulationTechnical Contacts:R. Benedict, NRR(301) 504-1157S. M. Shaeffer, R11(615) 842-8001Attachment:List of Recently Issued NRC Information NoticesSee previous concurrenceOFFICE l *OEAB:DORS *DRP:RII *OGCB:DORS l *SC/DRP:RII *TECH EDNAME } RBenedict SMShaeffer PCWen MLesser MFMejacDATE 1 05/04/94 1_05/05/94 1 05/05/94 _ 05/05/94 1 05/05/94*AC/SRXB:DSSA *AD/DSSA j *C/OEAB:DORS AC/OGCB:DORS D/DORSTECollins MVirgilio AChaffee AJKugler i(: BKGrimes05/06/94 = 05/09/94 05/09/94 5/1V94 / /94DOCUMENT NAME:SEQGASIN.RV1NOTE: The PMs for Sequoyah (D. LaBarge) and Salem (J.informed of the development of this informationreviewed the draft information notice.Stone) have beennotice and they havePeter Wen, 5/10/94 IN 94-xxMay xx, 1994 This information notice requires no specific action or writttten response.you have any questions about the information in this notice, please contactthe technical contact listed below or the appropriate Office of NuclearReactor Regulation (NRR) project manager.IfBrian K. Grimes, DirectorDivision of Operating Reactor SupportOffice of Nuclear Reactor RegulationTechnical Contacts:R. Benedict, NRR(301) 504-1157S. M. Shaeffer, RII(615) 842-8001Attachment:List of Recently Issued NRC Information NoticesOFFICE IOEABDOR5 DRP:RIIpcyJ OGCB_ _ _ SC/DRP:RI TECH EDNAME Benedict 'MShaeffer PCWen LesserDATE </A/94 5 /5/94 5 / 94/94 5//94 5 / 5/94AC/SRXB:DSSA , AD/DSSA j C/OEAB:DORS AC/OGCB:DORS D/DORSTEColli MVirgil ' A2 fe AJKugler BKGrimes_____94 /$\/94 /947/94 94 / /94UULUMtN I NAML:x 01 I J//qbtbAbI1 N.KV1jp'A4Mi: THE R& FR FoY(AH (-. LAMRPE) Azb 6MPA (j. )ROeia^ SoF'E Deospwt oF Ttts um. waIce ARD'NW ME .F) T"E JPV O D0e bWf ^ .&4-vhiw S/o/oA4.
reviewed the draft information


IN 94-36May 24, 1994 This information notice requires no specific action or written response. Ifyou have any questions about the information in this notice, please contactone of the technical contacts listed below or the appropriate Office ofNuclear Reactor Regulation (NRR) project manager.orig /s/'d by BKGrimesBrian K. Grimes, DirectorDivision of Operating Reactor SupportOffice of Nuclear Reactor RegulationTechnical contacts:R. Benedict, NRR(301) 504-1157S. M. Shaeffer, R11(615) 842-8001Attachment:List of Recently Issued NRC Information Notices*See Previous concurrenceE OFFICE *OEAB:DORS *DRP:RII *OGCB:DORS *SC/DRP:RII *TECH EDNAME RBenedict SMShaeffer PCWen MLesser MFMejacDATE j05/04/94 05/05/94 05/05/94 05/05/94 05/05/94l*AC/SRXB:DSSA *AD/DSSA 5*C/OEAB:DORS *AC/OGCB:DO RS*TECollins MVirgilio AChaffee AJKugler Iv _s05/06/94 05/09/94 i 05/09/94 05/12/4 05//f/94UuUMtrII NAM t:vq-io. INNOTE: The PMs for Sequoyah (D. LaBarge) and Salem (J.informed of the development of this informationreviewed the draft information notice.Stone) have beennotice and they havePeter Wen, 5/10/94  
notice.Stone) have been notice and they have Peter Wen, 5/10/94}}
}}


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Revision as of 13:59, 31 August 2018

Undetected Accumulation of Gas in Reactor Coolant System
ML031060539
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, Three Mile Island, 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  Entergy icon.png
Issue date: 05/24/1994
From: Grimes B K
Office of Nuclear Reactor Regulation
To:
References
-nr IN-94-036, NUDOCS 9405190137
Download: ML031060539 (10)
v • d • e


UNITED STATES P/-3Y NUCLEAR REGULATORY

COMMISSION

OFFICE OF NUCLEAR REACTOR REGULATION

WASHINGTON, D.C. 20555 May 24, 1994 NRC INFORMATION

NOTICE 94-36: UNDETECTED

ACCUMULATION

OF GAS IN REACTOR COOLANT SYSTEM

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 problems that could result from unrecognized

evolution

and accumulation

of gas in reactor coolant system high points. It is expected that recipients

will review this 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

Sequoyah Unit I had been shut down in March 1993. In early September

1993, after the unit had been refueled, the reactor vessel was reassembled

and the reactor coolant system was degassed, filled, and vented. The reactor coolant system was then depressurized

to atmospheric

pressure.

One pressurizer

power-operated relief valve (PORV) was open and the reactor coolant system average temperature

was being maintained

at approximately

49C [120'F]. Nitrogen cover gas was being supplied to the volume control tank at approximately

239 kPa [20 psig] and reactor coolant was being circulated

by the charging system and the residual heat removal (RHR) system. The reactor vessel level indication

system (RVLIS) was functional

for a significant

portion of the event. Before this event, instrument

maintenance

stickers were placed on the RVLIS indicators

for other maintenance

work. Although the RVLIS information

was available, the operators

were not monitoring

this information

because it was not procedurally

required to be used in shutdown modes of operation.

Reactor coolant system inventory

was being monitored

using pressurizer

cold calibration

level indications.

On December 17, 1993, the operators

began to pressurize

the containment

to 191 kPa [13 psig] in order to perform a containment

integrated

leak rate test.As containment

pressure increased, the operators

noticed a decrease in pressurizer

water level and, over a period of time, added approximately

31,400 liters [8,300 gallons] of water to maintain the pressurizer

level. Licensee personnel

evaluated

this situation

and recognized

that gas was accumulating

in the reactor coolant system. However, they failed to recognize

the magnitude 9405190137 po\ fit JE ote qq-f3tn 9t1S EsoI'I'

..~ -IN 94-36 May 24, 1994 or cause of the problem. Three days later, as the containment

was being depressurized

upon completion

of the containment

leak test, the operators noted that approximately

the same amount of water had to be removed from the reactor coolant system to maintain the level. On December 21, 1993, on the basis of operators'

observations

of the changing coolant system Inventory during the containment

leak test, the reactor vessel head was vented. It was subsequently

vented several times to maintain appropriate

reactor vessel inventory

based on RYLIS information.

The reactor vessel gas voiding conditions

went undetected

from early September

1993, when the reactor coolant system was verified to be filled, until December 21, 1993, when the reactor head was vented.The gas evolution

resulted from the temperature

in the volume control tank being much lower than that normally expected. (This lower temperature

was due to unusually

low component

cooling water temperatures

and to a maintenance

problem with a cooling water valve that resulted in the reduction

of the heat sink temperature

in the letdown heat exchanger.)

The lower temperatures

increased

the solubility

of gas in the volume control tank water so that more gas was dissolved

in the water. This gas evolved when the water was transferred

to the reactor coolant system by the charging system and heated up in the reactor vessel.Further details concerning

this event are in NRC Inspection

Report No. 50-327;50-328/94-04.

Discussion

The licensee completed

a final evaluation

in January 1994 and determined

that during this event the reactor vessel water level had decreased

to slightly below the top of the hot leg, and that the steam generator

tubes were nearly empty. The reactor coolant system inventory

was being monitored

solely on the basis of pressurizer

level, which was not indicative

of the reactor vessel and steam generator

levels. Calculations

by the licensee indicated

that an equilibrium

had been reached during the event so that the water level was approximately

1.6 meters [5.25 feet] above the top of the core. Any additional

gas evolved in the reactor vessel would be expected to be vented through the hot leg and surge line to the pressurizer

and out through the open pressurizer

PORV.The reactor water level at which equilibrium

was established

at Sequoyah was sufficiently

high so as not to interfere

with reactor coolant flow through the RHR cooling system. However, at other plants, the equilibrium

level, which is related to pressurizer

surge line geometry and RHR suction line location, might be such that a similar event could interfere

with shutdown cooling.Another potential

safety concern is related to the capability

of the steam generators

to transfer heat from the reactor coolant to secondary

coolant. In the equilibrium

condition

at Sequoyah, the steam generator

tubes were almost empty during at least a portion of the duration of this event. During this

IN 94-36--JMay 24, 1994 period, the steam generators

were assumed to be available

as an alternate means for shutdown cooling. It is not clear that cooling through the steam generators

could have been established, if needed, especially

because the plant operators

were unaware that the tubes were empty.Several factors involving

licensee performance

contributed

to the delay in the identification

and evaluation

of this event. They included (1) lack of consideration

on the part of licensee personnel

with respect to compression

of gas in the system caused by containment

pressure transmitted

to the reactor coolant system water through the open pressurizer

PORV; (2) misunderstanding

by the operators

about the operability

of RVLIS; (3) failure to stop the containment

leak test when water level changes were first noted so that the situation

could have been adequately

evaluated;

(4) an apparent lack of thorough evaluation

of previously

published

information

on similar events.The event discussed

in this information

notice highlights

the potential

for gas evolution

and accumulation

in the reactor coolant system in locations

and quantities

that may not be evident to operators.

Changes in temperature

and pressure can have significant

effects on the solubility

of gas in water, especially

at or near atmospheric

pressure conditions.

During cold shutdown, this phenomenon

can permit significant

quantities

of cover gas to be dissolved in lower-temperature, higher-pressure

volumes such as the volume control tank and to evolve into a large gas bubble in the reactor vessel (a lower-pressure, higher-temperature

area). This phenomenon

can occur without a sudden change in pressurizer

level, which is the indicator

normally used by the operators

to monitor water inventory.

Use of available

instrumentation

in shutdown modes to monitor reactor vessel water level can provide detection

of unexpected

system conditions

when reduced vessel inventory

is not planned as well as in reduced inventory

evolutions.

On April 12, 1994, a similar gas accumulation

event was identified

at the Salem Generating

Station (Unit 1) shortly after it entered Mode 5 (cold shutdown)

operation.

Although this occurrence

did not involve amounts of gas accumulation

as large as in the Sequoyah event, many similarities

existed regarding

both the process of gas formation

and the lack of operator awareness of the abnormal condition.

In both events, reactor vessel level information

was or could have been made available

for prompt identification

of the problem.Related Generic Communications

  • NRC Information

Notice 93-12, "Off-Gassing

in Auxiliary

Feedwater System Raw Water Sources," discusses

similar solubility

considerations

related to air pockets in piping at the McGuire Nuclear Station.* NRC Information

Notice 87-46, "Undetected

Loss of Reactor Coolant," discusses

undetected

loss of reactor coolant inventory at North Anna Unit 1 resulting

from inadequate

use of available indications

and failure to perform mass inventory

balances.

-\ > <_IN 94-36 May 24, 1994 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

Of ice of Nuclear Reactor Regulation (NRR) project manager.Brian K. Grimes, Director Division of Operating

Reactor Support Office of Nuclear Reactor Regulation

Technical

contacts:

R. Benedict, NRR (301) 504-1157 S. M. Shaeffer, RII (615) 842-8001 Attachment:

List of Recently Issued NRC Information

Notices

I At,.thment

IN 94-36 May 24, 1994 LIST OF RECENTLY ISSUED NRC INFORMATION

NOTICES Information

Date of Notice No. Subject Issuance Issued to 91-81, Supp. 1 94-35 94-34 94-33 93-53, Supp. 1 94-32 94-31 90-68, Supp. 1 94-30 Switchyard

Problems that Contribute

to Loss of Offsite Power NIOSH Respirator

User Notices, "Inadvertent

Separation

of the Mask-Mounted Regulator (MMR)from the Facepiece

on the Mine Safety Appliances (MSA)Company MMR Self-Contained

Breathing

Apparatus (SCBA)and Status Update Thermo-Lag

330-660 Flexi-Blanket

Ampacity Derating Concerns Capacitor

Failures in Westinghouse

Eagle 21 Plant Protection

Systems Effect of Hurricane Andrew on Turkey Point Nuclear Generating

Station and Lessons Learned Revised Seismic Hazard Estimates Potential

Failure of Wilco, Lexan-Type

HN-4-L Fire Hose Nozzles Stress Corrosion

Cracking of Reactor Coolant Pump Bolts Leaking Shutdown Cooling Isolation

Valves at Cooper Nuclear Station 05/19/94 05/16/94 05/13/94 05/09/94 04/29/94 04/29/94 04/14/94 04/14/94 04/12/94 All holders of OLs or CPs for nuclear power reactors.All holders of OLs or CPs for nuclear power reactors, and all licensed fuel facilities.

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 holders of 01 or CPs for pressurized

water reactors.All holders of OLs or CPs for nuclear power reactors.OL -Operating

License CP -Construction

Permit

IN 94-xx May 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 one of the technical

contacts listed below or the appropriate

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

Reactor Support Office of Nuclear Reactor Regulation

Technical

contacts: R. Benedict, NRR (301) 504-1157 S. M. Shaeffer, R11 (615) 842-8001 Attachment:

List of Recently Issued NRC Information

Notices*See Dnrvinim- concurrence

wBw _. _ .-1 _._OFFICE *OEAB:DORS

  • DRP:RII *OGCB:DORS
  • SC/DRP:RII
  • TECH ED NAME RBenedict

SMShaeffer

PCWen MLesser MFMejaclDATE 05/04/L94

05/05/94 05/05/94 05/05/94 05/05/94[*AC/SRXB:DSSA

  • AD/DSSA *C/OEAB:DORS
  • AC/OGCB:DORS

D/DORS TECollins

MVirgilio

AChaffee AJKugler BKGrimes 05/06/94 05/09/94 05/09/94 05.12/94 / /94 DOCUMENT NAME: SLQGAbIN.KV1 NOTE: The PMs for Sequoyah (D. LaBarge) and Salem (J.informed of the development

of this information

reviewed the draft information

notice.Stone) have been notice and they have Peter Wen, 5/10/94 IN 94-xx May 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 Operating

Reactor Support Office of Nuclear Reactor Regulation

Technical

Contacts: R. Benedict, NRR (301) 504-1157 S. M. Shaeffer, RI!(615) 842-8001 Attachment:

List of Recently Issued NRC Information

Notices*See previous concurrence

OFFICE *OEAB:DORS

  • DRP:RII *OGCB:DORS
  • SC/DRP:RII
  • TECH ED NAME RBenedict

SMShaeffer

PCWen MLesser MFMejac DATE 05/04/94 05/05/94 05/05/94 05/05/94 05/05/94*AC/SRXB:DSSA

  • AD/DSSA *C/OEAB:DORS
  • AC/OGCB:DORS

D/DORS TECollins

8EXI MVirgilio

I AChaffee AJKugler BKGrimes 05/06/94 1 05/09/94 05/09/94 05/12/94 / /94 nnlflMFNT

IAMr. eCnveCTit

niti.-- -- I ia11 I EAdIL* .JLA(Un4.1 n .* r A NOTE: The PMs for Sequoyah (D. LaBarge) and Salem (J.informed of the development

of this information

reviewed the draft information

notice.Stone) have been notice and they have Peter Wen, 5/10/94 IN 94-xx May 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 Operating

Reactor Support Office of Nuclear Reactor Regulation

Technical

Contacts: R. Benedict, NRR (301) 504-1157 S. M. Shaeffer, R11 (615) 842-8001 Attachment:

List of Recently Issued NRC Information

Notices See previous concurrence

OFFICE l *OEAB:DORS

  • DRP:RII *OGCB:DORS

l *SC/DRP:RII

  • TECH ED NAME } RBenedict

SMShaeffer

PCWen MLesser MFMejac DATE 1 05/04/94 1_05/05/94

1 05/05/94 _ 05/05/94 1 05/05/94*AC/SRXB:DSSA

  • AD/DSSA j *C/OEAB:DORS

AC/OGCB:DORS

D/DORS TECollins

MVirgilio

AChaffee AJKugler i(: BKGrimes 05/06/94 = 05/09/94 05/09/94 5/1V94 / /94 DOCUMENT NAME: SEQGASIN.RV1 NOTE: The PMs for Sequoyah (D. LaBarge) and Salem (J.informed of the development

of this information

reviewed the draft information

notice.Stone) have been notice and they have Peter Wen, 5/10/94 IN 94-xx May xx, 1994 This information

notice requires no specific action or writttten

response.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.If Brian K. Grimes, Director Division of Operating

Reactor Support Office of Nuclear Reactor Regulation

Technical

Contacts: R. Benedict, NRR (301) 504-1157 S. M. Shaeffer, RII (615) 842-8001 Attachment:

List of Recently Issued NRC Information

Notices OFFICE IOEABDOR5 DRP:RIIpcyJ

OGCB_ _ _ SC/DRP:RI

TECH ED NAME Benedict 'MShaeffer

PCWen Lesser DATE </A/94 5 /5/94 5 / 94/94 5//94 5 / 5/94 AC/SRXB:DSSA , AD/DSSA j C/OEAB:DORS

AC/OGCB:DORS

D/DORS TEColli MVirgil ' A2 fe AJKugler BKGrimes_____94 /$\/94 /947/94 94 / /94 UULUMtN I NAML: x 01 I J//q btbAbI1 N.KV1 jp'A4Mi: THE R& FR FoY(AH (-. LAMRPE) Azb 6MPA (j. )ROeia^ SoF'E Deospwt oF Ttts um. waIce ARD'NW ME .F) T"E JPV O D0e bWf ^ .&4-vhiw S/o/oA4.

IN 94-36 May 24, 1994 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

Office of Nuclear Reactor Regulation (NRR) project manager.orig /s/'d by BKGrimes Brian K. Grimes, Director Division of Operating

Reactor Support Office of Nuclear Reactor Regulation

Technical

contacts: R. Benedict, NRR (301) 504-1157 S. M. Shaeffer, R11 (615) 842-8001 Attachment:

List of Recently Issued NRC Information

Notices*See Previous concurrence

E OFFICE *OEAB:DORS

  • DRP:RII *OGCB:DORS
  • SC/DRP:RII
  • TECH ED NAME RBenedict

SMShaeffer

PCWen MLesser MFMejac DATE j05/04/94

05/05/94 05/05/94 05/05/94 05/05/94l*AC/SRXB:DSSA

  • AD/DSSA 5*C/OEAB:DORS
  • AC/OGCB:DO

RS*TECollins

MVirgilio

AChaffee AJKugler Iv _s 05/06/94 05/09/94 i 05/09/94 05/12/4 05//f/94 UuUMtrII NAM t: vq-io. IN NOTE: The PMs for Sequoyah (D. LaBarge) and Salem (J.informed of the development

of this information

reviewed the draft information

notice.Stone) have been notice and they have Peter Wen, 5/10/94


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