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

From kanterella
Jump to navigation Jump to search
(Created page by program invented by StriderTol)
(Created page by program invented by StriderTol)
 
Line 15: Line 15:
| page count = 10
| page count = 10
}}
}}
{{#Wiki_filter:UNITED STATES P/-3Y NUCLEAR REGULATORY
{{#Wiki_filter:UNITED STATES


COMMISSION
NUCLEAR REGULATORY COMMISSION


===OFFICE OF NUCLEAR REACTOR REGULATION===
P/-3Y
WASHINGTON, D.C. 20555 May 24, 1994 NRC INFORMATION


NOTICE 94-36: UNDETECTED
OFFICE OF NUCLEAR REACTOR REGULATION


ACCUMULATION
WASHINGTON, D.C. 20555 May 24, 1994 NRC INFORMATION NOTICE 94-36:  UNDETECTED ACCUMULATION OF GAS IN REACTOR


OF GAS IN REACTOR COOLANT SYSTEM
COOLANT SYSTEM


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


licenses or construction
reactors.
 
permits for nuclear power reactors.


==Purpose==
==Purpose==
The U.S. Nuclear Regulatory
The U.S. Nuclear Regulatory Commission (NRC) is issuing this information
 
Commission (NRC) is issuing this information
 
notice to alert addressees
 
to 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
notice to alert addressees to problems that could result from unrecognized


was being maintained
evolution and accumulation of gas in reactor coolant system high points. It


at approximately
is expected that recipients will review this information for applicability to


49C [120'F]. Nitrogen cover gas was being supplied to the volume control tank at approximately
their facilities and consider actions, as appropriate, to avoid similar


239 kPa [20 psig] and reactor coolant was being circulated
problems. However, suggestions contained in this information notice are not


by the charging system and the residual heat removal (RHR) system. The reactor vessel level indication
NRC requirements; therefore, no specific action or written response is


system (RVLIS) was functional
required.


for a significant
==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


portion of the event. Before this event, instrument
reactor coolant system was degassed, filled, and vented. The reactor coolant


maintenance
system was then depressurized to atmospheric pressure. One pressurizer power- operated relief valve (PORV) was open and the reactor coolant system average


stickers were placed on the RVLIS indicators
temperature was being maintained at approximately 49C [120'F]. Nitrogen


for other maintenance
cover gas was being supplied to the volume control tank at approximately


work. Although the RVLIS information
239 kPa [20 psig] and reactor coolant was being circulated by the charging


was available, the operators
system and the residual heat removal (RHR) system. The reactor vessel level


were not monitoring
indication system (RVLIS) was functional for a significant portion of the


this information
event. Before this event, instrument maintenance stickers were placed on the


because it was not procedurally
RVLIS indicators for other maintenance work. Although the RVLIS information


required to be used in shutdown modes of operation.
was available, the operators were not monitoring this information because it


Reactor coolant system inventory
was not procedurally required to be used in shutdown modes of operation.


was being monitored
Reactor coolant system inventory was being monitored using pressurizer cold


using pressurizer
calibration level indications.


cold calibration
On December 17, 1993, the operators began to pressurize the containment to


level indications.
191 kPa [13 psig] in order to perform a containment integrated leak rate test.


On December 17, 1993, the operators
As containment pressure increased, the operators noticed a decrease in


began to pressurize
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


the containment
personnel evaluated this situation and recognized that gas was accumulating in


to 191 kPa [13 psig] in order to perform a containment
the reactor coolant system. However, they failed to recognize the magnitude


integrated
9405190137      po\ fit              JEote          qq-f3tn          9t1S EsoI


leak rate test.As containment
'I'


pressure increased, the operators
:..~-IN94-36 May 24, 1994 or cause of the problem. Three days later, as the containment was being


noticed a decrease in pressurizer
depressurized upon completion of the containment leak test, the operators


water level and, over a period of time, added approximately
noted that approximately the same amount of water had to be removed from the


31,400 liters [8,300 gallons] of water to maintain the pressurizer
reactor coolant system to maintain the level. On December 21, 1993, on the


level. Licensee personnel
basis of operators' observations of the changing coolant system Inventory


evaluated
during the containment leak test, the reactor vessel head was vented. It was


this situation
subsequently vented several times to maintain appropriate reactor vessel


and recognized
inventory based on RYLIS information. The reactor vessel gas voiding


that gas was accumulating
conditions went undetected from early September 1993, when the reactor coolant


in the reactor coolant system. However, they failed to recognize
system was verified to be filled, until December 21, 1993, when the reactor


the magnitude 9405190137 po\ fit JE ote qq-f3tn 9t1S EsoI'I'
head was vented.
:..~ -IN 94-36 May 24, 1994 or cause of the problem. Three days later, as the containment


was being depressurized
The gas evolution resulted from the temperature in the volume control tank


upon completion
being much lower than that normally expected. (This lower temperature was due


of the containment
to unusually low component cooling water temperatures and to a maintenance


leak test, the operators noted that approximately
problem with a cooling water valve that resulted in the reduction of the heat


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'
sink temperature in the letdown heat exchanger.) The lower temperatures
observations


of the changing coolant system Inventory during the containment
increased the solubility of gas in the volume control tank water so that more


leak test, the reactor vessel head was vented. It was subsequently
gas was dissolved in the water. This gas evolved when the water was


vented several times to maintain appropriate
transferred to the reactor coolant system by the charging system and heated up


reactor vessel inventory
in the reactor vessel.


based on RYLIS information.
Further details concerning this event are in NRC Inspection Report No. 50-327;
 
50-328/94-04.
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
Discussion


The licensee completed
The licensee completed a final evaluation in January 1994 and determined that


a final evaluation
during this event the reactor vessel water level had decreased to slightly


in January 1994 and determined
below the top of the hot leg, and that the steam generator tubes were nearly


that during this event the reactor vessel water level had decreased
empty. The reactor coolant system inventory was being monitored solely on the


to slightly below the top of the hot leg, and that the steam generator
basis of pressurizer level, which was not indicative of the reactor vessel and


tubes were nearly empty. The reactor coolant system inventory
steam generator levels. Calculations by the licensee indicated that an


was being monitored
equilibrium had been reached during the event so that the water level was


solely on the basis of pressurizer
approximately 1.6 meters [5.25 feet] above the top of the core. Any


level, which was not indicative
additional gas evolved in the reactor vessel would be expected to be vented


of the reactor vessel and steam generator
through the hot leg and surge line to the pressurizer and out through the open


levels. Calculations
pressurizer PORV.


by the licensee indicated
The reactor water level at which equilibrium was established at Sequoyah was


that an equilibrium
sufficiently high so as not to interfere with reactor coolant flow through the


had been reached during the event so that the water level was approximately
RHR cooling system. However, at other plants, the equilibrium level, which is


1.6 meters [5.25 feet] above the top of the core. Any additional
related to pressurizer surge line geometry and RHR suction line location, might be such that a similar event could interfere with shutdown cooling.


gas evolved in the reactor vessel would be expected to be vented through the hot leg and surge line to the pressurizer
Another potential safety concern is related to the capability of the steam


and out through the open pressurizer
generators to transfer heat from the reactor coolant to secondary coolant. In


PORV.The reactor water level at which equilibrium
the equilibrium condition at Sequoyah, the steam generator tubes were almost


was established
empty during at least a portion of the duration of this event. During this


at Sequoyah was sufficiently
IN 94-36
                                                          --JMay 24, 1994 period, the steam generators were assumed to be available as an alternate


high so as not to interfere
means for shutdown cooling. It is not clear that cooling through the steam


with reactor coolant flow through the RHR cooling system. However, at other plants, the equilibrium
generators could have been established, if needed, especially because the


level, which is related to pressurizer
plant operators were unaware that the tubes were empty.


surge line geometry and RHR suction line location, might be such that a similar event could interfere
Several factors involving licensee performance contributed to the delay in the


with shutdown cooling.Another potential
identification and evaluation of this event. They included (1) lack of


safety concern is related to the capability
consideration on the part of licensee personnel with respect to compression of


of the steam generators
gas in the system caused by containment pressure transmitted to the reactor


to transfer heat from the reactor coolant to secondary
coolant system water through the open pressurizer PORV; (2) misunderstanding


coolant. In the equilibrium
by the operators about the operability of RVLIS; (3) failure to stop the


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


at Sequoyah, the steam generator
situation could have been adequately evaluated; (4) an apparent lack of


tubes were almost empty during at least a portion of the duration of this event. During this
thorough evaluation of previously published information on similar events.


IN 94-36--JMay 24, 1994 period, the steam generators
The event discussed in this information notice highlights the potential for


were assumed to be available
gas evolution and accumulation in the reactor coolant system in locations and


as an alternate means for shutdown cooling. It is not clear that cooling through the steam generators
quantities that may not be evident to operators. Changes in temperature and


could have been established, if needed, especially
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


because the plant operators
in lower-temperature, higher-pressure volumes such as the volume control tank


were unaware that the tubes were empty.Several factors involving
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


licensee performance
in pressurizer level, which is the indicator normally used by the operators to


contributed
monitor water inventory. Use of available instrumentation in shutdown modes


to the delay in the identification
to monitor reactor vessel water level can provide detection of unexpected


and evaluation
system conditions when reduced vessel inventory is not planned as well as in


of this event. They included (1) lack of consideration
reduced inventory evolutions.


on the part of licensee personnel
On April 12, 1994, a similar gas accumulation event was identified at the


with respect to compression
Salem Generating Station (Unit 1) shortly after it entered Mode 5 (cold


of gas in the system caused by containment
shutdown) operation. Although this occurrence did not involve amounts of gas


pressure transmitted
accumulation as large as in the Sequoyah event, many similarities existed


to the reactor coolant system water through the open pressurizer
regarding both the process of gas formation and the lack of operator awareness


PORV; (2) misunderstanding
of the abnormal condition. In both events, reactor vessel level information


by the operators
was or could have been made available for prompt identification of the


about the operability
problem.


of RVLIS; (3) failure to stop the containment
Related Generic Communications


leak test when water level changes were first noted so that the situation
*    NRC Information Notice 93-12, "Off-Gassing in Auxiliary Feedwater


could have been adequately
System Raw Water Sources," discusses similar solubility


evaluated;
considerations related to air pockets in piping at the McGuire
(4) an apparent lack of thorough evaluation


of previously
Nuclear Station.


published
*    NRC Information Notice 87-46, "Undetected Loss of Reactor


information
Coolant," discusses undetected loss of reactor coolant inventory


on similar events.The event discussed
at North Anna Unit 1 resulting from inadequate use of available


in this information
indications and failure to perform mass inventory balances.


notice highlights
-                    \                                  >
                                                        <_IN  94-36 May 24, 1994 This information notice requires no specific action or written response. If


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


for gas evolution
one of the technical contacts listed below or the appropriate Of ice of


and accumulation
Nuclear Reactor Regulation (NRR) project manager.


in the reactor coolant system in locations
Brian K. Grimes, Director


and quantities
Division of Operating Reactor Support


that may not be evident to operators.
Office of Nuclear Reactor Regulation


Changes in temperature
Technical contacts:  R. Benedict, NRR


and pressure can have significant
(301) 504-1157 S. M. Shaeffer, RII


effects on the solubility
(615) 842-8001 Attachment:


of gas in water, especially
===List of Recently Issued NRC Information Notices===


at or near atmospheric
I                                                At,.thment


pressure conditions.
IN 94-36 May 24, 1994 LIST OF RECENTLY ISSUED


During cold shutdown, this phenomenon
NRC INFORMATION NOTICES


can permit significant
Information                                    Date of


quantities
Notice No.              Subject                Issuance  Issued to


of cover gas to be dissolved in lower-temperature, higher-pressure
91-81,         Switchyard Problems that      05/19/94  All holders of OLs or CPs


volumes such as the volume control tank and to evolve into a large gas bubble in the reactor vessel (a lower-pressure, higher-temperature
Supp. 1        Contribute to Loss of                    for nuclear power reactors.


area). This phenomenon
Offsite Power


can occur without a sudden change in pressurizer
94-35          NIOSH Respirator User          05/16/94  All holders of OLs or CPs


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


normally used by the operators
Mounted Regulator (MMR)                  facilities.


to monitor water inventory.
from the Facepiece on the


Use of available
Mine Safety Appliances (MSA)
                Company MMR Self-Contained


instrumentation
Breathing Apparatus (SCBA)
                and Status Update


in shutdown modes to monitor reactor vessel water level can provide detection
94-34          Thermo-Lag 330-660            05/13/94  All holders of OLs or CPs


of unexpected
Flexi-Blanket Ampacity                    for nuclear power reactors.


system conditions
Derating Concerns


when reduced vessel inventory
94-33          Capacitor Failures in          05/09/94  All holders of OLs or CPs


is not planned as well as in reduced inventory
Westinghouse Eagle 21                      for nuclear power reactors.


evolutions.
Plant Protection Systems


On April 12, 1994, a similar gas accumulation
93-53,         Effect of Hurricane            04/29/94  All holders of OLs or CPs


event was identified
Supp. 1        Andrew on Turkey Point                    for nuclear power reactors.


at the Salem Generating
Nuclear Generating


Station (Unit 1) shortly after it entered Mode 5 (cold shutdown)
Station and Lessons Learned
operation.


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


did not involve amounts of gas accumulation
Estimates                                  for nuclear power reactors.


as large as in the Sequoyah event, many similarities
94-31          Potential Failure of          04/14/94  All holders of OLs or CPs


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


both the process of gas formation
Fire Hose Nozzles


and the lack of operator awareness of the abnormal condition.
90-68,        Stress Corrosion Cracking      04/14/94    All holders of 01 or CPs


===In both events, reactor vessel level information===
Supp. 1        of Reactor Coolant Pump                    for pressurized water
was or could have been made available


for prompt identification
Bolts                                      reactors.


of the problem.Related Generic Communications
94-30          Leaking Shutdown Cooling      04/12/94    All holders of OLs or CPs


* NRC Information
Isolation Valves at                      for nuclear power reactors.


Notice 93-12, "Off-Gassing
Cooper Nuclear Station


in Auxiliary
OL - Operating License


Feedwater System Raw Water Sources," discusses
CP - Construction Permit


similar solubility
IN 94-xx


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


related to air pockets in piping at the McGuire Nuclear Station.* NRC Information
you have any questions about the information in this notice, please contact


Notice 87-46, "Undetected
one of the technical contacts listed below or the appropriate Office of


Loss of Reactor Coolant," discusses
Nuclear Reactor Regulation (NRR) project manager.


undetected
Brian K. Grimes, Director


loss of reactor coolant inventory at North Anna Unit 1 resulting
Division of Operating Reactor Support


from inadequate
Office of Nuclear Reactor Regulation


use of available indications
Technical contacts:            R. Benedict, NRR


and failure to perform mass inventory
(301) 504-1157 S. M. Shaeffer, R11
                              (615) 842-8001 Attachment:
List of Recently Issued NRC Information Notices


balances.
*See  Dnrvinim- wBw


-\ > <_IN 94-36 May 24, 1994 This information
concurrence


notice requires no specific action or written response.
-_. _    .


If you have any questions
---  -                            1                    _._
  OFFICE    *OEAB:DORS          *DRP:RII      *OGCB:DORS    *SC/DRP:RII    *TECH ED


about the information
NAME      RBenedict            SMShaeffer    PCWen        MLesser        MFMejac


in this notice, please contact one of the technical
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


contacts listed below or the appropriate
TECollins            MVirgilio        AChaffee        AJKugler          BKGrimes


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


===Reactor Support Office of Nuclear Reactor Regulation===
informed of the development of this information notice and they have
Technical


contacts:
reviewed the draft information notice.
R. Benedict, NRR (301) 504-1157 S. M. Shaeffer, RII (615) 842-8001 Attachment:
List of Recently Issued NRC Information


Notices
Peter Wen, 5/10/94


===I At,.thment===
IN 94-xx
IN 94-36 May 24, 1994 LIST OF RECENTLY ISSUED NRC INFORMATION


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


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


Problems that Contribute
the technical contact listed below or the appropriate Office of Nuclear


to Loss of Offsite Power NIOSH Respirator
Reactor Regulation (NRR) project manager.


User Notices, "Inadvertent
Brian K. Grimes, Director


Separation
Division of Operating Reactor Support


of the Mask-Mounted Regulator (MMR)from the Facepiece
Office of Nuclear Reactor Regulation


on the Mine Safety Appliances (MSA)Company MMR Self-Contained
Technical Contacts:            R. Benedict, NRR


Breathing
(301) 504-1157 S. M. Shaeffer, RI!
                                  (615) 842-8001 Attachment:
  List of Recently Issued NRC Information Notices


Apparatus (SCBA)and Status Update Thermo-Lag
*See previous concurrence


330-660 Flexi-Blanket
OFFICE        *OEAB:DORS      *DRP:RII      *OGCB:DORS  *SC/DRP:RII    *TECH ED


Ampacity Derating Concerns Capacitor
NAME          RBenedict        SMShaeffer    PCWen        MLesser        MFMejac


Failures in Westinghouse
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


Eagle 21 Plant Protection
TECollins 8EXI            MVirgilio I AChaffee        AJKugler        BKGrimes


Systems Effect of Hurricane Andrew on Turkey Point Nuclear Generating
05/06/94              1  05/09/94      05/09/94        05/12/94          / /94 nnlflMFNT        IAMr. eCnveCTitn .* niti


Station and Lessons Learned Revised Seismic Hazard Estimates Potential
.-- -- I ia11 I EAdIL* .JLA(Un4.1    r A


Failure of Wilco, Lexan-Type
NOTE: The PMs for Sequoyah (D.LaBarge) and Salem (J.Stone) have been


HN-4-L Fire Hose Nozzles Stress Corrosion
informed of the development of this information notice and they have


Cracking of Reactor Coolant Pump Bolts Leaking Shutdown Cooling Isolation
reviewed the draft information notice.


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.
Peter Wen, 5/10/94


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
IN 94-xx


water reactors.All holders of OLs or CPs for nuclear power reactors.OL -Operating
May xx, 1994 This information notice requires no specific action or written response. If


License CP -Construction
you have any questions about the information in this notice, please contact


Permit
the technical contact listed below or the appropriate Office of Nuclear


IN 94-xx May xx, 1994 This information
Reactor Regulation (NRR) project manager.


notice requires no specific action or written response.
Brian K. Grimes, Director


If you have any questions
Division of Operating Reactor Support


about the information
Office of Nuclear Reactor Regulation


in this notice, please contact one of the technical
Technical Contacts:    R. Benedict, NRR


contacts listed below or the appropriate
(301) 504-1157 S. M. Shaeffer, R11
                        (615) 842-8001 Attachment:


Office of Nuclear Reactor Regulation (NRR) project manager.Brian K. Grimes, Director Division of Operating
===List of Recently Issued NRC Information Notices===
See previous concurrence


===Reactor Support Office of Nuclear Reactor Regulation===
OFFICE  l *OEAB:DORS    *DRP:RII      *OGCB:DORS l *SC/DRP:RII    *TECH ED
Technical


contacts: R. Benedict, NRR (301) 504-1157 S. M. Shaeffer, R11 (615) 842-8001 Attachment:
NAME    } RBenedict      SMShaeffer    PCWen        MLesser        MFMejac
List of Recently Issued NRC Information


Notices*See Dnrvinim- concurrence
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


---- wBw _. _ .-1 _._OFFICE *OEAB:DORS
TECollins        MVirgilio    AChaffee        AJKugler i(:   BKGrimes


*DRP:RII *OGCB:DORS
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


*SC/DRP:RII
informed of the development of this information notice and they have


*TECH ED NAME RBenedict
reviewed the draft information notice.


SMShaeffer
Peter Wen, 5/10/94


PCWen MLesser MFMejaclDATE 05/04/L94
IN 94-xx
05/05/94 05/05/94 05/05/94 05/05/94[*AC/SRXB:DSSA


*AD/DSSA *C/OEAB:DORS
May xx, 1994 This information notice requires no specific action or writttten response. If


*AC/OGCB:DORS
you have any questions about the information in this notice, please contact


D/DORS TECollins
the technical contact listed below or the appropriate Office of Nuclear


MVirgilio
Reactor Regulation (NRR) project manager.


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
Brian K. Grimes, Director


of this information
Division of Operating Reactor Support


reviewed the draft information
Office of Nuclear Reactor Regulation


notice.Stone) have been notice and they have Peter Wen, 5/10/94 IN 94-xx May xx, 1994 This information
Technical Contacts:      R. Benedict, NRR


notice requires no specific action or written response.
(301) 504-1157 S. M. Shaeffer, RII


If you have any questions
(615) 842-8001 Attachment:


about the information
===List of Recently Issued NRC Information Notices===
  OFFICE    IOEABDOR5      DRP:RIIpcyJ OGCB__    _    SC/DRP:RI      TECH ED


in this notice, please contact the technical
NAME        Benedict 'MShaeffer        PCWen          Lesser


contact listed below or the appropriate
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


Office of Nuclear Reactor Regulation (NRR) project manager.Brian K. Grimes, Director Division of Operating
TEColli            MVirgil '      A2            fe AJKugler        BKGrimes


===Reactor Support Office of Nuclear Reactor Regulation===
_____94
Technical
                        /$\/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


Contacts: R. Benedict, NRR (301) 504-1157 S. M. Shaeffer, RI!(615) 842-8001 Attachment:
'NW ME .F)       T"E JPV      OD0e bWf^ .
List of Recently Issued NRC Information


Notices*See previous concurrence
&4-vhiw S/o/oA4.


OFFICE *OEAB:DORS
IN 94-36 May 24, 1994 This information notice requires no specific action or written response. If


*DRP:RII *OGCB:DORS
you have any questions about the information in this notice, please contact


*SC/DRP:RII
one of the technical contacts listed below or the appropriate Office of


*TECH ED NAME RBenedict
Nuclear Reactor Regulation (NRR) project manager.


SMShaeffer
orig /s/'d by BKGrimes


PCWen MLesser MFMejac DATE 05/04/94 05/05/94 05/05/94 05/05/94 05/05/94*AC/SRXB:DSSA
Brian K. Grimes, Director


*AD/DSSA *C/OEAB:DORS
Division of Operating Reactor Support


*AC/OGCB:DORS
Office of Nuclear Reactor Regulation


D/DORS TECollins
Technical contacts:    R. Benedict, NRR


8EXI MVirgilio
(301) 504-1157 S. M. Shaeffer, R11
                      (615) 842-8001 Attachment:


I AChaffee AJKugler BKGrimes 05/06/94 1 05/09/94 05/09/94 05/12/94 / /94 nnlflMFNT
===List of Recently Issued NRC Information Notices===
E


IAMr. eCnveCTit
*See Previous concurrence


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
OFFICE


of this information
NAME


reviewed the draft information
*OEAB:DORS


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


notice requires no specific action or written response.
*DRP:RII
 
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
SMShaeffer


PCWen MLesser MFMejac DATE 1 05/04/94 1_05/05/94
*OGCB:DORS
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.
PCWen
 
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
*SC/DRP:RII


*TECH ED NAME RBenedict
MLesser
 
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
*TECH ED


*AC/OGCB:DO
MFMejac


RS*TECollins
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


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


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


of this information
informed of the development of this information notice and they have


reviewed the draft information
reviewed the draft information notice.


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


Retrieved from "https://kanterella.com/w/index.php?title=Information_Notice_1994-36,_Undetected_Accumulation_of_Gas_in_Reactor_Coolant_System&oldid=2201194"