Information Notice 1993-45, Degradation of Shutdown Cooling System Performance: Difference between revisions

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{{#Wiki_filter:UNITED STATESNUCLEAR REGULATORY COMMISSIONOFFICE OF NUCLEAR REACTOR REGULATIONWASHINGTON, D.C. 20555June 16, 1993NRC INFORMATION NOTICE 93-45: DEGRADATION OF SHUTDOWN COOLINGSYSTEM PERFORMANCE
{{#Wiki_filter:UNITED STATES NUCLEAR REGULATORY
 
COMMISSION
 
===OFFICE OF NUCLEAR REACTOR REGULATION===
WASHINGTON, D.C. 20555 June 16, 1993 NRC INFORMATION
 
NOTICE 93-45: DEGRADATION
 
===OF SHUTDOWN COOLING SYSTEM PERFORMANCE===


==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 degradation of shutdown cooling systemperformance at the Oyster Creek Nuclear Generating Station resulting frominadequate operating procedures. It is expected that recipients will reviewthe information for applicability to their facilities and consider actions, asappropriate, to avoid similar problems. However, suggestions contained inthis information notice are not NRC requirements; therefore, no specificaction or written response is required.
The U.S. Nuclear Regulatory
 
Commission (NRC) is issuing this information
 
notice to alert addressees
 
to degradation
 
of shutdown cooling system performance
 
at the Oyster Creek Nuclear Generating
 
Station resulting
 
from inadequate
 
operating
 
procedures.
 
It is expected that recipients
 
will review the information
 
for applicability
 
to their facilities
 
and consider actions, as appropriate, to avoid similar problems.
 
However, suggestions
 
contained
 
in this information
 
notice are not NRC requirements;  
therefore, no specific action or written response is required.Description
 
of Circumstances
 
On January 23, 1993, the Oyster Creek Nuclear Generating
 
Station was in day 57 of the 14R refueling
 
outage. The plant was in a normal cold-shutdown
 
condition
 
with the primary containment
 
open and the reactor coolant system at about 43' C [110* F]. One reactor recirculation
 
loop was in service, one recirculation
 
loop was open, and the remaining
 
three recirculation
 
loops were either idled or isolated.
 
Two shutdown cooling loops were operating
 
with a combined flow rate of 11,735 liters per minute 13,100 gpm].In order to support the planned activities, the licensee elected to secure operation
 
of all recirculation
 
pumps and lower reactor water level. This configuration
 
would allow completion, in parallel, of recirculation
 
pump maintenance
 
activities
 
and main steam isolation
 
valve local leak rate testing.When the operators
 
lowered the reactor water level to approximately
 
419 cm (165 inches] above the top of active fuel and secured the running.recirculation
 
pump, the shutdown cooling water took the least resistance
 
path through the open recirculation
 
loop, and the majority of flow bypassed the core (see Attachment
 
1). During the time that the planned activities
 
were in progress, plant personnel
 
did not realize that shutdown cooling system performance
 
was degraded, allowing unmonitored
 
heatup of the reactor core.On January 25, 1993, after completing
 
the main steam isolation
 
valve local leak rate testing, an operations
 
engineer discovered
 
that the reactor vessel metal temperature
 
was about 109C 1228F] at the mid-vessel
 
point. Several 9306090036 PDI I.E No*[ct 3-. oj58 P ..'v1\
IN 93-45 June 16, 1993 Technical
 
Specifications
 
prerequisites
 
for exceeding
 
100. C [212 F] were not met, including
 
the requirement
 
to establish
 
primary containment
 
integrity.
 
After discovery, operators
 
took immediate
 
measures to reduce reactor coolant system water temperature
 
by first maximizing
 
flow in the two operating shutdown cooling loops and then placing a third shutdown cooling loop in service. Additionally, the reactor water level was raised to approximately
 
508 cm [200 inches] above the top of active fuel and a recirculation
 
pump was started.The immediate
 
cause of the event was determined
 
to be plant conditions
 
established
 
by a temporary
 
procedure
 
change to the shutdown cooling operating procedure
 
that failed to provide sufficient
 
forced flow through the reactor core to prevent thermal stratification.
 
The temporary
 
procedure
 
change had been implemented
 
to allow shutdown operations
 
with all recirculation
 
pumps secured and the nominal reactor water level less than the level at which spillover
 
from the core region to the annulus is assured (approximately
 
470 cm[185 inches] above the top of active fuel). The change had been developed from a draft engineering
 
evaluation, but did not include a requirement (stated in the body of the evaluation)
to maintain a specified
 
shutdown cooling flow of 22,712 liters per minute [6,000 gpm]. Instead, the usual shutdown cooling flow of about 11,735 liters per minute [3,100 gpm] was maintained
 
which, due to the specified
 
configuration, allowed the inadvertent
 
reactor heatup.Further details can be found in Licensee Event Report 50-219/93-002 and NRC Augmented
 
Inspection
 
Team Inspection
 
Report No. 50-219/93-80.
 
Discussion
 
This event at Oyster Creek indicated
 
that the temporary
 
procedure
 
change represented
 
a significant
 
procedure
 
revision and that the review process did not identify deficiencies
 
in the procedure
 
before it was implemented.
 
The temporary
 
procedure
 
change had been developed
 
from a draft engineering
 
evaluation
 
which concluded
 
that two shutdown cooling loops in operation
 
would adequately
 
cool the core. An additional
 
assumption
 
in the body of the evaluation
 
was that each loop of shutdown cooling would be operating
 
at its design flow rate of 11,356 liters per minute [3,000 gpm], for a total flow rate of 22,712 liters per minute [6,000 gpm]. This flow rate would be adequate to induce spillover
 
from the core region to the annulus at the reduced nominal water level. The temporary
 
procedure
 
change that implemented
 
the engineering
 
evaluation
 
did not require a minimum flow rate of 22,712 liters per minute [6,000 gpm]. As a result, the operators
 
following
 
the deficient
 
temporary
 
procedure
 
change placed two shutdown cooling loops in operation, but did not provide sufficient
 
shutdown cooling water to the reactor core to maintain reactor vessel temperatures.
 
In addition, the temporary
 
procedure
 
change contained
 
no provision
 
or guidance for monitoring
 
available
 
instruments
 
to ensure that decay heat was being adequately
 
removed from the reactor core.As part of the licensee corrective
 
actions, the licensee reviewed the effectiveness
 
of its safety review process concerning
 
temporary
 
changes and provided training on the subject of this event to all site personnel
 
who perform technical
 
and safety reviews.
 
IN 93-45 June 16, 1993 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
 
Offic of Nuclear Reactor Regulation (NRR) project manager.Brian K. Grimes, Director Division of Operating
 
===Reactor Support Office of Nuclear Reactor Regulation===
Technical
 
contacts:
James S. Stewart, RI (215) 337-5240 Peter C. Wen, NRR (301) 504-2832 Attachments:
1. Figure 1, *Oyster Creek Shutdown Cooling System Flow With Open Recirculation
 
Loop" 2. List of Recently Issued NRC Information
 
Notices
 
K. /I'l I Steam Flow *-4-TO Recirculation
 
# ~Loop Shutdown Cooling System (3 Cooling Loops)Figure 1 Attachment
 
1 1iK 93-45 June 16, 1993 Open Recirculation
 
Loop Oyster Creek Shutdown Cooling System Flow With Open Recirculation
 
Loop
 
I Attachment
 
2 IN 93-45 June 16, 1993 LIST OF RECENTLY ISSUED NRC INFORMATION
 
NOTICES Information
 
Date of Notice No. Subject Issuance Issued to 93-44 93-43 93-42 Operational
 
Challenges
 
During A Dual-Unit Transient Use of Inappropriate
 
Lubrication
 
Oils in Safety-Related
 
===Applications===
Failure of Anti-Rotation
 
Keys in Motor-Operated
 
Valves Manufactured
 
by Velan 06/15/93 06/10/93 06/09/93 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.93-41 One Hour Fire Endurance Test Results for Thermal Ceramics Kaowool, 3M Company FS-195 and 3M Company Interam E-50 Barrier Systems 05/28/93 All holders for nuclear of OLs or CPs power reactors.93-40 ,93-39 93-38 Fire Endurance
 
Test Results for Thermal Ceramics FP-60 Fire Barrier Material Radiation
 
Beams from Power Reactor Biolog-ical Shields Inadequate
 
Testing of Engineered
 
Safety Features Actuation System 05/26/93 05/25/93 05/24/93 All holders of OLs or CPs for nuclear power reactors.All holders of OLs or CPs for nuclear power reactors.All holders for nuclear of OLs or CPs power reactors.93-37 Eyebolts with Indeter-minate Properties
 
In-stalled in Limitorque
 
Valve Operator Housing Covers 05/19/93 All holders of OLs or CPs for nuclear power reactors.0L -Operating
 
License CP -Construction
 
Permit
 
IN 93-45 June 16, 1993 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.Original !1gnd by Brian K. Gdmeg Brian K. Grimes, Director Division of Operating
 
===Reactor Support Office of Nuclear Reactor Regulation===
Technical
 
contacts: James S. Stewart, RI (215) 337-5240 Peter C. Wen, NRR (301) 504-283], Attachments:
6 1. Figure 1, "Oyster Creek Shutdown Cooling System Flow With Open Recirculation
 
Loop'2. List of Recently Issued NRC Information
 
Notices*rFF pRmVrnus CONCURRFNCF
 
OFFICE *OGCB:DORS
 
*DRS:RI **SC:DRS:RI
 
**BC:DRS:RI
 
**D:DRS:RI
 
NAME PCWen/vsb
 
JSStewart
 
PKEapen JPDurr MWHodges DATE 04/29/93 05/03/93 03/19/93 03/19/A3 .03/19/93_______- _ .*Tech Ed. I *C:OGCB:DORS--
*D:DSSA:NRR
 
RSanders I GHMarcus ACThadani 04/29/93 05/10 05/24/93.=DOCUMENT NAME: 93-45.IN**SEE MEMO FROM M.. HODGES TO B.K. GRIMES DATED 3/19/93 PM (A. Dromerick), EAB (J. Carter) and AIT Team Leader (J. Beall) were consulted
 
during the development
 
of this IN.
 
IN 93-XX May xx, 1993 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: James S. Stewart, Region I (215) 337-5240 Peter C. Wen, NRR (301) 504-2832 Attachments:
1. Oyster Creek Shutdown Cooling System Flow With Open Recirculation
 
Loop 2. List of Recently Issued NRC Information
 
Notices*SEE PREVIOUS CONCURRENCE
 
OFFICE *OGCB:DORS
 
*DRS:RI **SC:DRS:RI
 
**BC:DRS:RI
 
**D:DRS:RI
 
NAME PCWen/vsb
 
JSStewart
 
PKEapen JPDurr MWHodges DATE l04/29/93 l05/03/93 I 03/19/93 l 03/19/93 l03/19/93*Tech Ed.*C:OGCB:DORS
 
D:DORS:NRR
 
I RSanders GHMarcus 04/29/93 _ 05/10/93 ;onf~~~l ----1F o I~tsPIm BKGrimes UULUIMNI NAMI: UIIrMUN .PW)05/ /93 4 xk)**SEE MEMO FROM M.W. HODGES TO B.K. GRIMES DATED 3/19/93 PM (A. Dromerick), EAB (J. Carter) and AIT Team Leader (J. Beall) were consulted
 
during the development
 
of this IN.530 ACiwAt #f A);mli v-AV'I/tllos
 
IN 93-XX May xx, 1993 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: James S. Stewart, Region I (215) 337-5240 Peter C. Wen, NRR (301) 504-2832 Attachments:
1.2.Oyster Creek Shutdown Cooling System Flow With Open Recirculation
 
Loop List of Recently Issued NRC Information
 
Notices*SEE PREVIOUS CONCURRENCE
 
.OFFICE *OGCB:DORS
 
DRS:RI SC:DRS:RI
 
BC:DRS:RI
 
D:DRS:RI NAME PCWen/vsb
 
4SStewart
 
PKEapen JPDurr MWHodges DATE 04/29/93 05/3,0 Cal P/1/93 0/ l/9 3 I__ 1_/93_J*Tech Ed.C:OGCB:DORS
 
D:DORS:NRR
 
4xx %E memo Fizz MYS 144 RSanders GHMarcus Ci~l BKGrimes 04/29/93 05/ 1q 9 93 1 05/ /93 44 1/1 A/ 3 DOUUMENT NAME: OCTPCIN.PW
 
PA (A 'rolnerlk&) , 1 (. Covte). t AlT Team Leader (J. &3eA.A) LxQe cuAJX4A Alxrzrl t. 4JeLt"e'4
.tk& z4 BJ
 
IN 93-XX May xx, 1993 Page 2 of 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


==Description of Circumstances==
===Reactor Support Office of Nuclear Reactor Regulation===
On January 23, 1993, the Oyster Creek Nuclear Generating Station was in day 57of the 14R refueling outage. The plant was in a normal cold-shutdowncondition with the primary containment open and the reactor coolant system atabout 43' C [110* F]. One reactor recirculation loop was in service, onerecirculation loop was open, and the remaining three recirculation loops wereeither idled or isolated. Two shutdown cooling loops were operating with acombined flow rate of 11,735 liters per minute 13,100 gpm].In order to support the planned activities, the licensee elected to secureoperation of all recirculation pumps and lower reactor water level. Thisconfiguration would allow completion, in parallel, of recirculation pumpmaintenance activities and main steam isolation valve local leak rate testing.When the operators lowered the reactor water level to approximately 419 cm(165 inches] above the top of active fuel and secured the running.recirculation pump, the shutdown cooling water took the least resistance paththrough the open recirculation loop, and the majority of flow bypassed thecore (see Attachment 1). During the time that the planned activities were inprogress, plant personnel did not realize that shutdown cooling systemperformance was degraded, allowing unmonitored heatup of the reactor core.On January 25, 1993, after completing the main steam isolation valve localleak rate testing, an operations engineer discovered that the reactor vesselmetal temperature was about 109C 1228F] at the mid-vessel point. Several9306090036 PDI I.E No*[ct 3-. oj58P ..'v1\
Technical
IN 93-45June 16, 1993 Technical Specifications prerequisites for exceeding 100. C [212 F] were notmet, including the requirement to establish primary containment integrity.After discovery, operators took immediate measures to reduce reactor coolantsystem water temperature by first maximizing flow in the two operatingshutdown cooling loops and then placing a third shutdown cooling loop inservice. Additionally, the reactor water level was raised to approximately508 cm [200 inches] above the top of active fuel and a recirculation pump wasstarted.The immediate cause of the event was determined to be plant conditionsestablished by a temporary procedure change to the shutdown cooling operatingprocedure that failed to provide sufficient forced flow through the reactorcore to prevent thermal stratification. The temporary procedure change hadbeen implemented to allow shutdown operations with all recirculation pumpssecured and the nominal reactor water level less than the level at whichspillover from the core region to the annulus is assured (approximately 470 cm[185 inches] above the top of active fuel). The change had been developedfrom a draft engineering evaluation, but did not include a requirement (statedin the body of the evaluation) to maintain a specified shutdown cooling flowof 22,712 liters per minute [6,000 gpm]. Instead, the usual shutdown coolingflow of about 11,735 liters per minute [3,100 gpm] was maintained which, dueto the specified configuration, allowed the inadvertent reactor heatup.Further details can be found in Licensee Event Report 50-219/93-002 and NRCAugmented Inspection Team Inspection Report No. 50-219/93-80.DiscussionThis event at Oyster Creek indicated that the temporary procedure changerepresented a significant procedure revision and that the review process didnot identify deficiencies in the procedure before it was implemented. Thetemporary procedure change had been developed from a draft engineeringevaluation which concluded that two shutdown cooling loops in operation wouldadequately cool the core. An additional assumption in the body of theevaluation was that each loop of shutdown cooling would be operating at itsdesign flow rate of 11,356 liters per minute [3,000 gpm], for a total flowrate of 22,712 liters per minute [6,000 gpm]. This flow rate would beadequate to induce spillover from the core region to the annulus at thereduced nominal water level. The temporary procedure change that implementedthe engineering evaluation did not require a minimum flow rate of 22,712liters per minute [6,000 gpm]. As a result, the operators following thedeficient temporary procedure change placed two shutdown cooling loops inoperation, but did not provide sufficient shutdown cooling water to thereactor core to maintain reactor vessel temperatures. In addition, thetemporary procedure change contained no provision or guidance for monitoringavailable instruments to ensure that decay heat was being adequately removedfrom the reactor core.As part of the licensee corrective actions, the licensee reviewed theeffectiveness of its safety review process concerning temporary changes andprovided training on the subject of this event to all site personnel whoperform technical and safety reviews.


IN 93-45June 16, 1993 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 Offic ofNuclear Reactor Regulation (NRR) project manager.Brian K. Grimes, DirectorDivision of Operating ReactorSupportOffice of Nuclear Reactor RegulationTechnical contacts: James S. Stewart, RI(215) 337-5240Peter C. Wen, NRR(301) 504-2832Attachments:1. Figure 1, *Oyster Creek Shutdown Cooling SystemFlow With Open Recirculation Loop"2. List of Recently Issued NRC Information Notices
contacts: James S. Stewart, Region I (215) 337-5240 Peter (301)C. Wen, NRR 504-2832 Attachments:
1.2.Oyster Creek Shutdown Cooling System Flow With Open Recirculation


K. /I'l ISteam Flow *-4-TO Recirculation# ~LoopShutdown CoolingSystem(3 Cooling Loops)Figure 1Attachment 11iK 93-45June 16, 1993 Open RecirculationLoopOyster Creek Shutdown Cooling System Flow With Open Recirculation Loop
Loop List of Recently Issued NRC Information


IAttachment 2IN 93-45June 16, 1993 LIST OF RECENTLY ISSUEDNRC INFORMATION NOTICESInformation Date ofNotice No. Subject Issuance Issued to93-4493-4393-42Operational ChallengesDuring A Dual-UnitTransientUse of InappropriateLubrication Oils inSafety-Related ApplicationsFailure of Anti-RotationKeys in Motor-OperatedValves Manufactured byVelan06/15/9306/10/9306/09/93All 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.93-41One Hour Fire EnduranceTest Results for ThermalCeramics Kaowool, 3MCompany FS-195 and3M Company Interam E-50Barrier Systems05/28/93All holdersfor nuclearof OLs or CPspower reactors.93-40,93-3993-38Fire Endurance TestResults for ThermalCeramics FP-60 FireBarrier MaterialRadiation Beams fromPower Reactor Biolog-ical ShieldsInadequate Testing ofEngineered SafetyFeatures ActuationSystem05/26/9305/25/9305/24/93All holders of OLs or CPsfor nuclear power reactors.All holders of OLs or CPsfor nuclear power reactors.All holdersfor nuclearof OLs or CPspower reactors.93-37Eyebolts with Indeter-minate Properties In-stalled in LimitorqueValve Operator HousingCovers05/19/93All holders of OLs or CPsfor nuclear power reactors.0L -Operating LicenseCP -Construction Permit
Notices OFFICE OBORS DRS:RI SC:DRS:RI


IN 93-45June 16, 1993 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.Original !1gnd byBrian K. GdmegBrian K. Grimes, DirectorDivision of Operating Reactor SupportOffice of Nuclear Reactor RegulationTechnical contacts:James S. Stewart, RI(215) 337-5240Peter C. Wen, NRR(301) 504-283],Attachments: 61. Figure 1, "Oyster Creek Shutdown Cooling SystemFlow With Open Recirculation Loop'2. List of Recently Issued NRC Information Notices*rFF pRmVrnus CONCURRFNCFOFFICE *OGCB:DORS *DRS:RI **SC:DRS:RI **BC:DRS:RI **D:DRS:RINAME PCWen/vsb JSStewart PKEapen JPDurr MWHodgesDATE 04/29/93 05/03/93 03/19/93 03/19/A3 .03/19/93_______- _ .*Tech Ed. I *C:OGCB:DORS--*D:DSSA:NRRRSanders I GHMarcus ACThadani04/29/93 05/10 05/24/93.=DOCUMENT NAME: 93-45.IN**SEE MEMO FROM M.. HODGES TO B.K. GRIMESDATED 3/19/93PM (A. Dromerick), EAB (J. Carter) and AITTeam Leader (J. Beall) were consulted duringthe development of this IN.
BC:DRS:RI


IN 93-XXMay xx, 1993 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:James S. Stewart, Region I(215) 337-5240Peter C. Wen, NRR(301) 504-2832Attachments:1. Oyster Creek Shutdown Cooling System Flow With Open Recirculation Loop2. List of Recently Issued NRC Information Notices*SEE PREVIOUS CONCURRENCEOFFICE *OGCB:DORS *DRS:RI **SC:DRS:RI **BC:DRS:RI **D:DRS:RINAME PCWen/vsb JSStewart PKEapen JPDurr MWHodgesDATE l04/29/93 l05/03/93 I 03/19/93 l 03/19/93 l03/19/93*Tech Ed.*C:OGCB:DORSD:DORS:NRRI RSanders GHMarcus04/29/93 _ 05/10/93 ;onf~~~l ----1F o I~tsPImBKGrimesUULUIMNI NAMI: UIIrMUN .PW)05/ /93 4xk)**SEE MEMO FROM M.W. HODGES TO B.K. GRIMESDATED 3/19/93PM (A. Dromerick), EAB (J. Carter) and AITTeam Leader (J. Beall) were consulted duringthe development of this IN.530ACiwAt #f A);mli v-AV'I/tllos
D:DRS:RI NAME PCWen/vsb


IN 93-XXMay xx, 1993 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:James S. Stewart, Region I(215) 337-5240Peter C. Wen, NRR(301) 504-2832Attachments:1.2.Oyster Creek Shutdown Cooling System Flow With Open Recirculation LoopList of Recently Issued NRC Information Notices*SEE PREVIOUS CONCURRENCE .OFFICE *OGCB:DORS DRS:RI SC:DRS:RI BC:DRS:RI D:DRS:RINAME PCWen/vsb 4SStewart PKEapen JPDurr MWHodgesDATE 04/29/93 05/3,0 Cal P/1/93 0/ l/93I__ 1_/93_J*Tech Ed.C:OGCB:DORSD:DORS:NRR4xx %E memoFizz MYS 144RSanders GHMarcus Ci~l BKGrimes04/29/93 05/ 1q993 1 05/ /9344 1/1 A/ 3DOUUMENT NAME: OCTPCIN.PWPA (A 'rolnerlk&) , 1 (. Covte). tAlT Team Leader (J. &3eA.A) LxQe cuAJX4AAlxrzrl t. 4JeLt"e'4 .tk& z4 BJ
JSStewart


IN 93-XXMay xx, 1993Page 2 ofThis 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:James S. Stewart, Region I(215) 337-5240Peter(301)C. Wen, NRR504-2832Attachments:1.2.Oyster Creek Shutdown Cooling System Flow With Open Recirculation LoopList of Recently Issued NRC Information NoticesOFFICE OBORS DRS:RI SC:DRS:RI BC:DRS:RI D:DRS:RINAME PCWen/vsb JSStewart PKEapen JPDurr MWHodgesDATE _/aq/93_ 05/ /93 05/ /93 05/ /93 105/ /93Tech Ed.C:OGCB:DORSD: DORS:NR RIflU"AJA& GHMarcus BKGrimesON/.11/93 05/ /93 05/ /93%^rrlT scur -rnT -abUUUMt Ii NAMt: ULIrMLIN.fW
PKEapen JPDurr MWHodges DATE _/aq/93_ 05/ /93 05/ /93 05/ /93 105/ /93 Tech Ed.C:OGCB:DORS


}}
D: DORS:NR RI flU"AJA& GHMarcus BKGrimes ON/.11/93
05/ /93 05/ /93%^rrlT scur -rnT -ab UUUMt Ii NAMt: ULIrMLIN.fW}}


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

Revision as of 13:54, 31 August 2018

Degradation of Shutdown Cooling System Performance
ML031070480
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: 06/16/1993
From: Grimes B K
Office of Nuclear Reactor Regulation
To:
References
IN-93-045, NUDOCS 9306090036
Download: ML031070480 (9)
v • d • e


UNITED STATES NUCLEAR REGULATORY

COMMISSION

OFFICE OF NUCLEAR REACTOR REGULATION

WASHINGTON, D.C. 20555 June 16, 1993 NRC INFORMATION

NOTICE 93-45: DEGRADATION

OF SHUTDOWN COOLING SYSTEM PERFORMANCE

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 degradation

of shutdown cooling system performance

at the Oyster Creek Nuclear Generating

Station resulting

from inadequate

operating

procedures.

It is expected that recipients

will review the information

for applicability

to their facilities

and consider actions, as appropriate, to avoid similar problems.

However, suggestions

contained

in this information

notice are not NRC requirements;

therefore, no specific action or written response is required.Description

of Circumstances

On January 23, 1993, the Oyster Creek Nuclear Generating

Station was in day 57 of the 14R refueling

outage. The plant was in a normal cold-shutdown

condition

with the primary containment

open and the reactor coolant system at about 43' C [110* F]. One reactor recirculation

loop was in service, one recirculation

loop was open, and the remaining

three recirculation

loops were either idled or isolated.

Two shutdown cooling loops were operating

with a combined flow rate of 11,735 liters per minute 13,100 gpm].In order to support the planned activities, the licensee elected to secure operation

of all recirculation

pumps and lower reactor water level. This configuration

would allow completion, in parallel, of recirculation

pump maintenance

activities

and main steam isolation

valve local leak rate testing.When the operators

lowered the reactor water level to approximately

419 cm (165 inches] above the top of active fuel and secured the running.recirculation

pump, the shutdown cooling water took the least resistance

path through the open recirculation

loop, and the majority of flow bypassed the core (see Attachment

1). During the time that the planned activities

were in progress, plant personnel

did not realize that shutdown cooling system performance

was degraded, allowing unmonitored

heatup of the reactor core.On January 25, 1993, after completing

the main steam isolation

valve local leak rate testing, an operations

engineer discovered

that the reactor vessel metal temperature

was about 109C 1228F] at the mid-vessel

point. Several 9306090036 PDI I.E No*[ct 3-. oj58 P ..'v1\

IN 93-45 June 16, 1993 Technical

Specifications

prerequisites

for exceeding

100. C [212 F] were not met, including

the requirement

to establish

primary containment

integrity.

After discovery, operators

took immediate

measures to reduce reactor coolant system water temperature

by first maximizing

flow in the two operating shutdown cooling loops and then placing a third shutdown cooling loop in service. Additionally, the reactor water level was raised to approximately

508 cm [200 inches] above the top of active fuel and a recirculation

pump was started.The immediate

cause of the event was determined

to be plant conditions

established

by a temporary

procedure

change to the shutdown cooling operating procedure

that failed to provide sufficient

forced flow through the reactor core to prevent thermal stratification.

The temporary

procedure

change had been implemented

to allow shutdown operations

with all recirculation

pumps secured and the nominal reactor water level less than the level at which spillover

from the core region to the annulus is assured (approximately

470 cm[185 inches] above the top of active fuel). The change had been developed from a draft engineering

evaluation, but did not include a requirement (stated in the body of the evaluation)

to maintain a specified

shutdown cooling flow of 22,712 liters per minute [6,000 gpm]. Instead, the usual shutdown cooling flow of about 11,735 liters per minute [3,100 gpm] was maintained

which, due to the specified

configuration, allowed the inadvertent

reactor heatup.Further details can be found in Licensee Event Report 50-219/93-002 and NRC Augmented

Inspection

Team Inspection

Report No. 50-219/93-80.

Discussion

This event at Oyster Creek indicated

that the temporary

procedure

change represented

a significant

procedure

revision and that the review process did not identify deficiencies

in the procedure

before it was implemented.

The temporary

procedure

change had been developed

from a draft engineering

evaluation

which concluded

that two shutdown cooling loops in operation

would adequately

cool the core. An additional

assumption

in the body of the evaluation

was that each loop of shutdown cooling would be operating

at its design flow rate of 11,356 liters per minute [3,000 gpm], for a total flow rate of 22,712 liters per minute [6,000 gpm]. This flow rate would be adequate to induce spillover

from the core region to the annulus at the reduced nominal water level. The temporary

procedure

change that implemented

the engineering

evaluation

did not require a minimum flow rate of 22,712 liters per minute [6,000 gpm]. As a result, the operators

following

the deficient

temporary

procedure

change placed two shutdown cooling loops in operation, but did not provide sufficient

shutdown cooling water to the reactor core to maintain reactor vessel temperatures.

In addition, the temporary

procedure

change contained

no provision

or guidance for monitoring

available

instruments

to ensure that decay heat was being adequately

removed from the reactor core.As part of the licensee corrective

actions, the licensee reviewed the effectiveness

of its safety review process concerning

temporary

changes and provided training on the subject of this event to all site personnel

who perform technical

and safety reviews.

IN 93-45 June 16, 1993 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

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

Reactor Support Office of Nuclear Reactor Regulation

Technical

contacts:

James S. Stewart, RI (215) 337-5240 Peter C. Wen, NRR (301) 504-2832 Attachments:

1. Figure 1, *Oyster Creek Shutdown Cooling System Flow With Open Recirculation

Loop" 2. List of Recently Issued NRC Information

Notices

K. /I'l I Steam Flow *-4-TO Recirculation

  1. ~Loop Shutdown Cooling System (3 Cooling Loops)Figure 1 Attachment

1 1iK 93-45 June 16, 1993 Open Recirculation

Loop Oyster Creek Shutdown Cooling System Flow With Open Recirculation

Loop

I Attachment

2 IN 93-45 June 16, 1993 LIST OF RECENTLY ISSUED NRC INFORMATION

NOTICES Information

Date of Notice No. Subject Issuance Issued to 93-44 93-43 93-42 Operational

Challenges

During A Dual-Unit Transient Use of Inappropriate

Lubrication

Oils in Safety-Related

Applications

Failure of Anti-Rotation

Keys in Motor-Operated

Valves Manufactured

by Velan 06/15/93 06/10/93 06/09/93 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.93-41 One Hour Fire Endurance Test Results for Thermal Ceramics Kaowool, 3M Company FS-195 and 3M Company Interam E-50 Barrier Systems 05/28/93 All holders for nuclear of OLs or CPs power reactors.93-40 ,93-39 93-38 Fire Endurance

Test Results for Thermal Ceramics FP-60 Fire Barrier Material Radiation

Beams from Power Reactor Biolog-ical Shields Inadequate

Testing of Engineered

Safety Features Actuation System 05/26/93 05/25/93 05/24/93 All holders of OLs or CPs for nuclear power reactors.All holders of OLs or CPs for nuclear power reactors.All holders for nuclear of OLs or CPs power reactors.93-37 Eyebolts with Indeter-minate Properties

In-stalled in Limitorque

Valve Operator Housing Covers 05/19/93 All holders of OLs or CPs for nuclear power reactors.0L -Operating

License CP -Construction

Permit

IN 93-45 June 16, 1993 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.Original !1gnd by Brian K. Gdmeg Brian K. Grimes, Director Division of Operating

Reactor Support Office of Nuclear Reactor Regulation

Technical

contacts: James S. Stewart, RI (215) 337-5240 Peter C. Wen, NRR (301) 504-283], Attachments:

6 1. Figure 1, "Oyster Creek Shutdown Cooling System Flow With Open Recirculation

Loop'2. List of Recently Issued NRC Information

Notices*rFF pRmVrnus CONCURRFNCF

OFFICE *OGCB:DORS

  • DRS:RI **SC:DRS:RI
    • BC:DRS:RI
    • D:DRS:RI

NAME PCWen/vsb

JSStewart

PKEapen JPDurr MWHodges DATE 04/29/93 05/03/93 03/19/93 03/19/A3 .03/19/93_______- _ .*Tech Ed. I *C:OGCB:DORS--

  • D:DSSA:NRR

RSanders I GHMarcus ACThadani 04/29/93 05/10 05/24/93.=DOCUMENT NAME: 93-45.IN**SEE MEMO FROM M.. HODGES TO B.K. GRIMES DATED 3/19/93 PM (A. Dromerick), EAB (J. Carter) and AIT Team Leader (J. Beall) were consulted

during the development

of this IN.

IN 93-XX May xx, 1993 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: James S. Stewart, Region I (215) 337-5240 Peter C. Wen, NRR (301) 504-2832 Attachments:

1. Oyster Creek Shutdown Cooling System Flow With Open Recirculation

Loop 2. List of Recently Issued NRC Information

Notices*SEE PREVIOUS CONCURRENCE

OFFICE *OGCB:DORS

  • DRS:RI **SC:DRS:RI
    • BC:DRS:RI
    • D:DRS:RI

NAME PCWen/vsb

JSStewart

PKEapen JPDurr MWHodges DATE l04/29/93 l05/03/93 I 03/19/93 l 03/19/93 l03/19/93*Tech Ed.*C:OGCB:DORS

D:DORS:NRR

I RSanders GHMarcus 04/29/93 _ 05/10/93 ;onf~~~l ----1F o I~tsPIm BKGrimes UULUIMNI NAMI: UIIrMUN .PW)05/ /93 4 xk)**SEE MEMO FROM M.W. HODGES TO B.K. GRIMES DATED 3/19/93 PM (A. Dromerick), EAB (J. Carter) and AIT Team Leader (J. Beall) were consulted

during the development

of this IN.530 ACiwAt #f A);mli v-AV'I/tllos

IN 93-XX May xx, 1993 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: James S. Stewart, Region I (215) 337-5240 Peter C. Wen, NRR (301) 504-2832 Attachments:

1.2.Oyster Creek Shutdown Cooling System Flow With Open Recirculation

Loop List of Recently Issued NRC Information

Notices*SEE PREVIOUS CONCURRENCE

.OFFICE *OGCB:DORS

DRS:RI SC:DRS:RI

BC:DRS:RI

D:DRS:RI NAME PCWen/vsb

4SStewart

PKEapen JPDurr MWHodges DATE 04/29/93 05/3,0 Cal P/1/93 0/ l/9 3 I__ 1_/93_J*Tech Ed.C:OGCB:DORS

D:DORS:NRR

4xx %E memo Fizz MYS 144 RSanders GHMarcus Ci~l BKGrimes 04/29/93 05/ 1q 9 93 1 05/ /93 44 1/1 A/ 3 DOUUMENT NAME: OCTPCIN.PW

PA (A 'rolnerlk&) , 1 (. Covte). t AlT Team Leader (J. &3eA.A) LxQe cuAJX4A Alxrzrl t. 4JeLt"e'4

.tk& z4 BJ

IN 93-XX May xx, 1993 Page 2 of 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: James S. Stewart, Region I (215) 337-5240 Peter (301)C. Wen, NRR 504-2832 Attachments:

1.2.Oyster Creek Shutdown Cooling System Flow With Open Recirculation

Loop List of Recently Issued NRC Information

Notices OFFICE OBORS DRS:RI SC:DRS:RI

BC:DRS:RI

D:DRS:RI NAME PCWen/vsb

JSStewart

PKEapen JPDurr MWHodges DATE _/aq/93_ 05/ /93 05/ /93 05/ /93 105/ /93 Tech Ed.C:OGCB:DORS

D: DORS:NR RI flU"AJA& GHMarcus BKGrimes ON/.11/93

05/ /93 05/ /93%^rrlT scur -rnT -ab UUUMt Ii NAMt: ULIrMLIN.fW


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