Information Notice 1994-36, Undetected Accumulation of Gas in Reactor Coolant System: Difference between revisions

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| issue date = 05/24/1994
| issue date = 05/24/1994
| title = Undetected Accumulation of Gas in Reactor Coolant System
| title = Undetected Accumulation of Gas in Reactor Coolant System
| author name = Grimes B K
| author name = Grimes B
| author affiliation = NRC/NRR
| author affiliation = NRC/NRR
| addressee name =  
| addressee name =  
Line 14: Line 14:
| document type = NRC Information Notice
| document type = NRC Information Notice
| page count = 10
| page count = 10
| revision = 0
}}
}}
{{#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
 
NUCLEAR REGULATORY COMMISSION
 
P/-3Y
 
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==
==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 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'  
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
:..~ -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 balance \ > <_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) 842-8001
 
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               JEote          qq-f3tn           9t1S EsoI
 
'I'
 
:..~-IN94-36 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,          Switchyard Problems that      05/19/94  All holders of OLs or CPs
 
Supp. 1        Contribute to Loss of                    for nuclear power reactors.
 
Offsite Power
 
94-35          NIOSH Respirator User          05/16/94  All holders of OLs or CPs
 
Notices, "Inadvertent                    for nuclear power reactors, Separation of the Mask-                  and all licensed fuel
 
Mounted Regulator (MMR)                  facilities.
 
from the Facepiece on the
 
Mine Safety Appliances (MSA)
                Company MMR Self-Contained
 
Breathing Apparatus (SCBA)
                and Status Update
 
94-34          Thermo-Lag 330-660            05/13/94  All holders of OLs or CPs
 
Flexi-Blanket Ampacity                    for nuclear power reactors.
 
Derating Concerns
 
94-33          Capacitor Failures in          05/09/94  All holders of OLs or CPs
 
Westinghouse Eagle 21                      for nuclear power reactors.
 
Plant Protection Systems
 
93-53,          Effect of Hurricane            04/29/94  All holders of OLs or CPs
 
Supp. 1        Andrew on Turkey Point                    for nuclear power reactors.
 
Nuclear Generating
 
Station and Lessons Learned
 
94-32          Revised Seismic Hazard        04/29/94  All holders of OLs or CPs
 
Estimates                                  for nuclear power reactors.
 
94-31          Potential Failure of          04/14/94  All holders of OLs or CPs
 
Wilco, Lexan-Type HN-4-L                  for nuclear power reactors.
 
Fire Hose Nozzles
 
90-68,        Stress Corrosion Cracking      04/14/94    All holders of 01 or CPs
 
Supp. 1        of Reactor Coolant Pump                    for pressurized water
 
Bolts                                      reactors.
 
94-30          Leaking Shutdown Cooling      04/12/94    All holders of OLs or CPs
 
Isolation Valves at                      for nuclear power reactors.
 
Cooper Nuclear Station
 
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- wBw
 
concurrence
 
-_. _    .
 
---  -                            1                    _._
  OFFICE    *OEAB:DORS          *DRP:RII      *OGCB:DORS    *SC/DRP:RII    *TECH ED
 
NAME      RBenedict            SMShaeffer    PCWen        MLesser        MFMejac
 
lDATE      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. Stone) have been
 
informed of the development of this information notice and they have
 
reviewed the draft information notice.
 
Peter Wen, 5/10/94
 
IN 94-xx
 
May xx, 1994 This information notice requires no specific action or written response.
 
you have any questions about the information in this notice, please contactIf
 
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. eCnveCTitn .* niti
 
.-- -- I ia11 I EAdIL* .JLA(Un4.1    r A
 
NOTE: The PMs for Sequoyah (D.LaBarge) and Salem (J.Stone) have been
 
informed of the development of this information notice and they have
 
reviewed the draft information notice.
 
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. Stone) have been
 
informed of the development of this information notice and they have
 
reviewed the draft information notice.
 
Peter Wen, 5/10/94
 
IN 94-xx
 
May xx, 1994 This information notice requires no specific action or writttten 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, 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      jC/OEAB:DORS      AC/OGCB:DORS    D/DORS
 
TEColli            MVirgil '      A2            fe AJKugler        BKGrimes
 
_____94
                        /$\/94        /947/94            94            /  /94 UULUMtN I NAML: btbAbI1 N.KV1 x 01 I J//q            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      OD0e 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===
E
 
*See Previous concurrence
 
OFFICE
 
NAME
 
*OEAB:DORS
 
RBenedict
 
*DRP:RII
 
SMShaeffer
 
*OGCB:DORS
 
PCWen
 
*SC/DRP:RII
 
MLesser
 
*TECH ED
 
MFMejac


===Attachment:===
DATE    j05/04/94      05/05/94    05/05/94      05/05/94      05/05/94 l*AC/SRXB:DSSA    *AD/DSSA    5*C/OEAB:DORS    *AC/OGCB:DO RS*
List of Recently Issued NRC Information Notices 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 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) 842-8001
  TECollins        MVirgilio    AChaffee      IvAJKugler        _s


===Attachment:===
05/06/94         05/09/94   i 05/09/94       05/12/4          05//f/94 UuUMtrII NAMt:   vq-io. IN
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) 842-8001


===Attachment:===
NOTE: The PMs for Sequoyah (D. LaBarge) and Salem (J. Stone) have been
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) 842-8001


===Attachment:===
informed of the development of this information notice and they have
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) 842-8001


===Attachment:===
reviewed the draft information notice.
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/oA 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) 842-8001


===Attachment:===
Peter Wen, 5/10/94}}
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}}


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

Latest revision as of 04:28, 24 November 2019

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
Office of Nuclear Reactor Regulation
To:
References
-nr IN-94-036, NUDOCS 9405190137
Download: ML031060539 (10)
v • d • e


UNITED STATES

NUCLEAR REGULATORY COMMISSION

P/-3Y

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 JEote qq-f3tn 9t1S EsoI

'I'

..~-IN94-36 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

System Raw Water Sources," discusses similar solubility

considerations related to air pockets in piping at the McGuire

Nuclear Station.

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, Switchyard Problems that 05/19/94 All holders of OLs or CPs

Supp. 1 Contribute to Loss of for nuclear power reactors.

Offsite Power

94-35 NIOSH Respirator User 05/16/94 All holders of OLs or CPs

Notices, "Inadvertent for nuclear power reactors, Separation of the Mask- and all licensed fuel

Mounted Regulator (MMR) facilities.

from the Facepiece on the

Mine Safety Appliances (MSA)

Company MMR Self-Contained

Breathing Apparatus (SCBA)

and Status Update

94-34 Thermo-Lag 330-660 05/13/94 All holders of OLs or CPs

Flexi-Blanket Ampacity for nuclear power reactors.

Derating Concerns

94-33 Capacitor Failures in 05/09/94 All holders of OLs or CPs

Westinghouse Eagle 21 for nuclear power reactors.

Plant Protection Systems

93-53, Effect of Hurricane 04/29/94 All holders of OLs or CPs

Supp. 1 Andrew on Turkey Point for nuclear power reactors.

Nuclear Generating

Station and Lessons Learned

94-32 Revised Seismic Hazard 04/29/94 All holders of OLs or CPs

Estimates for nuclear power reactors.

94-31 Potential Failure of 04/14/94 All holders of OLs or CPs

Wilco, Lexan-Type HN-4-L for nuclear power reactors.

Fire Hose Nozzles

90-68, Stress Corrosion Cracking 04/14/94 All holders of 01 or CPs

Supp. 1 of Reactor Coolant Pump for pressurized water

Bolts reactors.

94-30 Leaking Shutdown Cooling 04/12/94 All holders of OLs or CPs

Isolation Valves at for nuclear power reactors.

Cooper Nuclear Station

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- wBw

concurrence

-_. _ .

--- - 1 _._

OFFICE *OEAB:DORS *DRP:RII *OGCB:DORS *SC/DRP:RII *TECH ED

NAME RBenedict SMShaeffer PCWen MLesser MFMejac

lDATE 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. Stone) have been

informed of the development of this information notice and they have

reviewed the draft information notice.

Peter Wen, 5/10/94

IN 94-xx

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

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

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. eCnveCTitn .* niti

.-- -- I ia11 I EAdIL* .JLA(Un4.1 r A

NOTE: The PMs for Sequoyah (D.LaBarge) and Salem (J.Stone) have been

informed of the development of this information notice and they have

reviewed the draft information notice.

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. Stone) have been

informed of the development of this information notice and they have

reviewed the draft information notice.

Peter Wen, 5/10/94

IN 94-xx

May xx, 1994 This information notice requires no specific action or writttten 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, 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 jC/OEAB:DORS AC/OGCB:DORS D/DORS

TEColli MVirgil ' A2 fe AJKugler BKGrimes

_____94

/$\/94 /947/94 94 / /94 UULUMtN I NAML: btbAbI1 N.KV1 x 01 I J//q 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 OD0e 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

E

  • See Previous concurrence

OFFICE

NAME

  • OEAB:DORS

RBenedict

  • DRP:RII

SMShaeffer

  • OGCB:DORS

PCWen

  • SC/DRP:RII

MLesser

MFMejac

DATE j05/04/94 05/05/94 05/05/94 05/05/94 05/05/94 l*AC/SRXB:DSSA *AD/DSSA 5*C/OEAB:DORS *AC/OGCB:DO RS*

TECollins MVirgilio AChaffee IvAJKugler _s

05/06/94 05/09/94 i 05/09/94 05/12/4 05//f/94 UuUMtrII NAMt: vq-io. IN

NOTE: The PMs for Sequoyah (D. LaBarge) and Salem (J. Stone) have been

informed of the development of this information notice and they have

reviewed the draft information notice.

Peter Wen, 5/10/94


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