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

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| issue date = 06/16/1993
| issue date = 06/16/1993
| title = Degradation of Shutdown Cooling System Performance
| title = Degradation of Shutdown Cooling System Performance
| author name = Grimes B K
| author name = Grimes B
| author affiliation = NRC/NRR
| author affiliation = NRC/NRR
| addressee name =  
| addressee name =  
Line 14: Line 14:
| page count = 9
| page count = 9
}}
}}
{{#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==
==Description of Circumstances==
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\  
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
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.
 
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 C [212 F] were not
 
Technical Specifications prerequisites for exceeding 100.                     integrity.
 
met, including the requirement to establish   primary     containment
 
measures    to  reduce      reactor    coolant
 
After discovery, operators took immediate                         two    operating
 
system water temperature by first   maximizing   flow   in the
 
cooling loop in
 
shutdown cooling loops and then placing a third shutdown             to approximately
 
service. Additionally, the reactor water level was raised   a  recirculation        pump was
 
508 cm [200 inches] above the   top of active fuel and
 
started.
 
conditions
 
The immediate cause of the event was determined to be plant cooling operating
 
established by a temporary procedure   change to the shutdown
 
through the reactor
 
procedure that failed to provide sufficient forced flow procedure            change had
 
core to prevent thermal stratification.   The temporary
 
pumps
 
been implemented to allow shutdown operations with all recirculationlevel at      which
 
secured and the nominal reactor water level less than the (approximately 470 cm
 
spillover from the core region to the annulus   is assured
 
been developed
 
[185 inches] above the top of active fuel). The change had         a requirement (stated
 
from a draft engineering evaluation, but did not includeshutdown cooling flow
 
in the body of the evaluation) to maintain a specified                   shutdown cooling
 
of 22,712 liters per minute [6,000 gpm]. Instead, the usual                     which, due
 
flow of about 11,735 liters per minute [3,100 gpm] was maintainedheatup.
 
to the specified configuration, allowed the inadvertent reactor
 
and NRC
 
Further details can be found in Licensee Event Report 50-219/93-002 Augmented Inspection Team Inspection Report No. 50-219/93-80.
 
Discussion
 
change
 
This event at Oyster Creek indicated that the temporary procedure   review    process    did
 
represented a significant procedure revision and that         the
 
was    implemented.        The
 
not identify deficiencies in the procedure before it                 engineering
 
temporary procedure change had been developed from a draft in operation would
 
evaluation which concluded that two shutdown cooling       loops
 
of the
 
adequately cool the core. An additional assumption in the body                       at its
 
evaluation was that each loop of shutdown cooling     would     be   operating
 
gpm],    for    a total    flow
 
design flow rate of 11,356 liters per minute [3,000                       would  be
 
rate of 22,712 liters per minute [6,000 gpm]. This       flow     rate
 
at the
 
adequate to induce spillover from the core region to the annulus         that  implemented
 
reduced nominal water level. The temporary procedure         change
 
flow    rate    of  22,712 the engineering evaluation did not require a minimum                               the
 
operators       following


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
liters per minute [6,000 gpm]. As a result, the                               loops    in


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
deficient temporary procedure change placed two    shutdown      cooling


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
cooling      water    to  the


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.
operation, but did not provide sufficient shutdown                  addition, the


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
reactor core to maintain reactor vessel temperatures. In                  for monitoring


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
temporary procedure change contained no provision    or   guidance


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
heat  was    being    adequately      removed


}}
available instruments to ensure that decay
 
from the reactor core.
 
the
 
As part of the licensee corrective actions, the licensee reviewedchanges and
 
effectiveness of its safety review process  concerning      temporary
 
who
 
provided training on the subject of this event to all site personnel
 
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
 
Attachment 1
                                                                        1iK 93-45 June 16, 1993 Steam Flow  *-
              4- Open Recirculation
 
TORecirculation                                              Loop
 
#    ~Loop
 
Shutdown Cooling
 
System
 
(3 Cooling Loops)
                                        Figure 1 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            Operational Challenges          06/15/93  All holders of OLs or CPs
 
During A Dual-Unit                        for nuclear power reactors.
 
Transient
 
93-43            Use of Inappropriate            06/10/93  All holders of OLs or CPs
 
Lubrication Oils in                        for nuclear power reactors.
 
Safety-Related Applications
 
93-42            Failure of Anti-Rotation        06/09/93  All holders of OLs or CPs
 
Keys in Motor-Operated                      for nuclear power reactors.
 
Valves Manufactured by
 
Velan
 
93-41            One Hour Fire Endurance          05/28/93  All holders of OLs or CPs
 
Test Results for Thermal                    for nuclear power reactors.
 
Ceramics Kaowool, 3M
 
Company FS-195 and
 
3M Company Interam E-50
                  Barrier Systems
 
93-40            Fire Endurance Test            05/26/93  All holders of OLs or CPs
 
Results for Thermal                        for nuclear power reactors.
 
Ceramics FP-60 Fire
 
Barrier Material
 
,93-39            Radiation Beams from            05/25/93  All holders of OLs or CPs
 
Power Reactor Biolog-                      for nuclear power reactors.
 
ical Shields
 
93-38            Inadequate Testing of          05/24/93  All holders of OLs or CPs
 
Engineered Safety                          for nuclear power reactors.
 
Features Actuation
 
System
 
93-37            Eyebolts with Indeter-          05/19/93  All holders of OLs or CPs
 
minate Properties In-                      for nuclear power reactors.
 
stalled in Limitorque
 
Valve Operator Housing
 
Covers
 
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    IGHMarcus          ACThadani
 
04/29/93      05/10            05/24/93
                                      **SEE MEMO FROM M.. HODGES TO B.K. GRIMES
 
=
                              .
 
DOCUMENT  NAME:    93-45.IN
 
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
 
IRSanders      GHMarcus              BKGrimes
 
04/29/93 _ 05/10/93                ;05/    /93      4 xk)
    onf~~~l                oI~tsPIm
 
- - - - 1F
 
UULUIMNI NAMI:    UIIrMUN .PW)          **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
                                                            AV 'I/tllos
 
ACiwAt  #
                                        fA);mli      v-
 
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    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          MYS
 
Fizz  144 RSanders    GHMarcus Ci~l BKGrimes                    44 1/1 A/3
  04/29/93    05/ 1q993      105/  /93 DOUUMENT NAME:    OCTPCIN.PW                      PA (A 'rolnerlk&) , 1      (. Covte).    t
 
AlT  Team Leader (J. &3eA.A)  LxQe cuAJX4A
 
Alxrzrl t.    4JeLt"e'4  . tk& z4BJ
 
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 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
 
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:NRRI
 
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}}

Latest revision as of 04:21, 24 November 2019

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
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 C [212 F] were not

Technical Specifications prerequisites for exceeding 100. integrity.

met, including the requirement to establish primary containment

measures to reduce reactor coolant

After discovery, operators took immediate two operating

system water temperature by first maximizing flow in the

cooling loop in

shutdown cooling loops and then placing a third shutdown to approximately

service. Additionally, the reactor water level was raised a recirculation pump was

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

started.

conditions

The immediate cause of the event was determined to be plant cooling operating

established by a temporary procedure change to the shutdown

through the reactor

procedure that failed to provide sufficient forced flow procedure change had

core to prevent thermal stratification. The temporary

pumps

been implemented to allow shutdown operations with all recirculationlevel at which

secured and the nominal reactor water level less than the (approximately 470 cm

spillover from the core region to the annulus is assured

been developed

[185 inches] above the top of active fuel). The change had a requirement (stated

from a draft engineering evaluation, but did not includeshutdown cooling flow

in the body of the evaluation) to maintain a specified shutdown cooling

of 22,712 liters per minute [6,000 gpm]. Instead, the usual which, due

flow of about 11,735 liters per minute [3,100 gpm] was maintainedheatup.

to the specified configuration, allowed the inadvertent reactor

and NRC

Further details can be found in Licensee Event Report 50-219/93-002 Augmented Inspection Team Inspection Report No. 50-219/93-80.

Discussion

change

This event at Oyster Creek indicated that the temporary procedure review process did

represented a significant procedure revision and that the

was implemented. The

not identify deficiencies in the procedure before it engineering

temporary procedure change had been developed from a draft in operation would

evaluation which concluded that two shutdown cooling loops

of the

adequately cool the core. An additional assumption in the body at its

evaluation was that each loop of shutdown cooling would be operating

gpm], for a total flow

design flow rate of 11,356 liters per minute [3,000 would be

rate of 22,712 liters per minute [6,000 gpm]. This flow rate

at the

adequate to induce spillover from the core region to the annulus that implemented

reduced nominal water level. The temporary procedure change

flow rate of 22,712 the engineering evaluation did not require a minimum the

operators following

liters per minute [6,000 gpm]. As a result, the loops in

deficient temporary procedure change placed two shutdown cooling

cooling water to the

operation, but did not provide sufficient shutdown addition, the

reactor core to maintain reactor vessel temperatures. In for monitoring

temporary procedure change contained no provision or guidance

heat was being adequately removed

available instruments to ensure that decay

from the reactor core.

the

As part of the licensee corrective actions, the licensee reviewedchanges and

effectiveness of its safety review process concerning temporary

who

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

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

Attachment 1

1iK 93-45 June 16, 1993 Steam Flow *-

4- Open Recirculation

TORecirculation Loop

  1. ~Loop

Shutdown Cooling

System

(3 Cooling Loops)

Figure 1 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 Operational Challenges 06/15/93 All holders of OLs or CPs

During A Dual-Unit for nuclear power reactors.

Transient

93-43 Use of Inappropriate 06/10/93 All holders of OLs or CPs

Lubrication Oils in for nuclear power reactors.

Safety-Related Applications

93-42 Failure of Anti-Rotation 06/09/93 All holders of OLs or CPs

Keys in Motor-Operated for nuclear power reactors.

Valves Manufactured by

Velan

93-41 One Hour Fire Endurance 05/28/93 All holders of OLs or CPs

Test Results for Thermal for nuclear power reactors.

Ceramics Kaowool, 3M

Company FS-195 and

3M Company Interam E-50

Barrier Systems

93-40 Fire Endurance Test 05/26/93 All holders of OLs or CPs

Results for Thermal for nuclear power reactors.

Ceramics FP-60 Fire

Barrier Material

,93-39 Radiation Beams from 05/25/93 All holders of OLs or CPs

Power Reactor Biolog- for nuclear power reactors.

ical Shields

93-38 Inadequate Testing of 05/24/93 All holders of OLs or CPs

Engineered Safety for nuclear power reactors.

Features Actuation

System

93-37 Eyebolts with Indeter- 05/19/93 All holders of OLs or CPs

minate Properties In- for nuclear power reactors.

stalled in Limitorque

Valve Operator Housing

Covers

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 IGHMarcus ACThadani

04/29/93 05/10 05/24/93

    • SEE MEMO FROM M.. HODGES TO B.K. GRIMES

=

.

DOCUMENT NAME: 93-45.IN

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

IRSanders GHMarcus BKGrimes

04/29/93 _ 05/10/93 ;05/ /93 4 xk)

onf~~~l oI~tsPIm

- - - - 1F

UULUIMNI NAMI: UIIrMUN .PW) **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

AV 'I/tllos

ACiwAt #

fA);mli v-

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 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 MYS

Fizz 144 RSanders GHMarcus Ci~l BKGrimes 44 1/1 A/3

04/29/93 05/ 1q993 105/ /93 DOUUMENT NAME: OCTPCIN.PW PA (A 'rolnerlk&) , 1 (. Covte). t

AlT Team Leader (J. &3eA.A) LxQe cuAJX4A

Alxrzrl t. 4JeLt"e'4 . tk& z4BJ

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 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

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:NRRI

flU"AJA& GHMarcus BKGrimes

ON/.11/93 05/ /93 05/ /93

%^rrlT scur -rnT -ab

UUUMt Ii NAMt: ULIrMLIN.fW


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