Information Notice 1992-39, Unplanned Return to Criticality During Reactor Shutdown: Difference between revisions

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{{#Wiki_filter:UNITED STATES NUCLEAR REGULATORY
{{#Wiki_filter:UNITED STATES


COMMISSION
NUCLEAR REGULATORY COMMISSION


===OFFICE OF NUCLEAR REACTOR REGULATION===
OFFICE OF NUCLEAR REACTOR REGULATION
WASHINGTON, D.C. 20555 May 13, 1992 NRC INFORMATION


NOTICE 92-39: UNPLANNED
WASHINGTON, D.C. 20555 May 13, 1992 NRC INFORMATION NOTICE 92-39:   UNPLANNED RETURN TO CRITICALITY DURING


RETURN TO CRITICALITY
REACTOR SHUTDOWN
 
DURING REACTOR SHUTDOWN


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


permits for nuclear power reactors.
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 recent events involving
 
unplanned
 
returns to criticality
 
caused by the cooldown of the reactor coolant system during reactor shutdowns.
 
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
 
The licensees
 
for the following
 
plants recently experienced
 
unplanned criticalities


during reactor shutdowns:
notice to alert addressees to recent events involving unplanned returns to
the Monticello


===Nuclear Generating===
criticality caused by the cooldown of the reactor coolant system during reactor
Plant, the Big Rock Point Nuclear Plant, and the Grand Gulf Nuclear Station.Monticello


On June 6, 1991, an unplanned
shutdowns. It is expected that recipients will review the information for


criticality
applicability to their facilities and consider actions, as appropriate, to


occurred at the Monticello
avoid similar problems. However, suggestions contained in this information


Nuclear Generating
notice are not NRC requirements; therefore, no specific action or written


Plant during a reactor shutdown when an unanticipated
response is required.


cooldown occurred in conjunction
==Description of Circumstances==
The licensees for the following plants recently experienced unplanned


with rod insertion.
criticalities during reactor shutdowns: the Monticello Nuclear Generating


The licensee initiated
Plant, the Big Rock Point Nuclear Plant, and the Grand Gulf Nuclear Station.


this shutdown to repair a leaking safety-relief
Monticello


valve shortly after the plant was returning
On June 6, 1991, an unplanned criticality occurred at the Monticello Nuclear


to power following
Generating Plant during a reactor shutdown when an unanticipated cooldown


a refueling
occurred in conjunction with rod insertion. The licensee initiated this


outage.Since this shutdown occurred shortly after the cycle startup, the reactor did not generate sufficient
shutdown to repair a leaking safety-relief valve shortly after the plant was


decay heat to produce the steam needed to supply the normal steam system loads and still maintain pressure in the reactor. As control rods were being inserted using notch insertion, the reactor coolant system pressure and temperature
returning to power following a refueling outage.


began to decrease.
Since this shutdown occurred shortly after the cycle startup, the reactor did


As long as the operator continued
not generate sufficient decay heat to produce the steam needed to supply the


to insert control rods, the reactor remained subcritical.
normal steam system loads and still maintain pressure in the reactor. As


However, when the operator stopped inserting
control rods were being inserted using notch insertion, the reactor coolant


control rods to review and evaluate plant conditions, the cooldown continued, adding sufficient
system pressure and temperature began to decrease. As long as the operator


reactivity
continued to insert control rods, the reactor remained subcritical.


to overcome the negative reactivity
However, when the operator stopped inserting control rods to review and


from the insertion
evaluate plant conditions, the cooldown continued, adding sufficient


of control rods and causing the reactor power to increase.
reactivity to overcome the negative reactivity from the insertion of control


The reactor power continued
rods and causing the reactor power to increase. The reactor power continued to


to 92050_*,, C j'A i / 1 ( / /CDQc
92050_*
,,                                                                 j'A C


K)IN 92-39 May 13, 1992 increase until an intermediate-range
i /        1    (                /    /CDQc


monitor (IRM) tripped on a high-high
K)
                                                                  IN 92-39 May 13, 1992 increase until an intermediate-range monitor (IRM) tripped on a high-high flux


flux setpoint, causing a reactor scram.Further details of the event may be found in Licensee Event Report 50-263/91-15 or NRC Inspection
setpoint, causing a reactor scram.


Report 50-263/91-13.
Further details of the event may be found in Licensee Event Report


Big Rock Point On November 30, 1991, an unplanned
50-263/91-15 or NRC Inspection Report 50-263/91-13.


criticality
===Big Rock Point===
On November 30, 1991, an unplanned criticality occurred at the Big Rock Point


occurred at the Big Rock Point Nuclear Plant during a reactor shutdown when a cooldown occurred in conjunction
Nuclear Plant during a reactor shutdown when a cooldown occurred in conjunction


with a rod insertion.
with a rod insertion. The event occurred during a scheduled shutdown for a


The event occurred during a scheduled
refueling outage.


shutdown for a refueling
After taking the main turbine off line and bringing the reactor to a


outage.After taking the main turbine off line and bringing the reactor to a subcritical
subcritical condition, the licensee delayed actions to continue inserting


condition, the licensee delayed actions to continue inserting control rods while changing shifts. However, the reactor coolant system continued
control rods while changing shifts. However, the reactor coolant system


to cool down because the normal steam system loads were removing heat. The cooldown added sufficient
continued to cool down because the normal steam system loads were removing


reactivity
heat. The cooldown added sufficient reactivity to eventually overcome the


to eventually
effects of the control rods, and the reactor returned critical. The operators


overcome the effects of the control rods, and the reactor returned critical.
noticed the condition in approximately 2 minutes and took the appropriate
 
The operators noticed the condition
 
in approximately
 
2 minutes and took the appropriate


actions to return the reactor subcritical.
actions to return the reactor subcritical.


Further details of the event may be found in Licensee Event Report 50-155/91-OO9-orJNRC-Inspection-Report
Further details of the event may be found in Licensee Event Report
 
50-155/91-25.


_ _ _Grand Gulf On December 30, 1991, an unplanned
50-155/91-OO9-orJNRC-Inspection-Report 50-155/91-25.        _ _             _
Grand Gulf


criticality
On December 30, 1991, an unplanned criticality occurred at the Grand Gulf


occurred at the Grand Gulf Nuclear Station during a reactor shutdown when a cooldown occurred in conjunction
Nuclear Station during a reactor shutdown when a cooldown occurred in


with a rod insertion.
conjunction with a rod insertion. The event occurred during a scheduled


The event occurred during a scheduled shutdown for a maintenance
shutdown for a maintenance outage to replace a recirculation pump shaft. To


outage to replace a recirculation
minimize the release of plated-out radioactive material from the fuel cladding


pump shaft. To minimize the release of plated-out
and channels to the reactor coolant system, a slow power reduction and a slow


radioactive
cooldown were prescribed for this shutdown.


material from the fuel cladding and channels to the reactor coolant system, a slow power reduction
The slow power reduction and the effects of an earlier outage minimized reactor


and a slow cooldown were prescribed
decay heat and xenon peaking. The operators were driving rods into the core


for this shutdown.The slow power reduction
individually because gang drive for the control rods was unavailable. This


and the effects of an earlier outage minimized
made the reactivity insertion slower than normal. The operators inserted


reactor decay heat and xenon peaking. The operators
rods to reduce flux to range 3 on the IRMs and stopped rod insertion in order


were driving rods into the core individually
to perform a source range monitor surveillance. Indicated power reached IRM


because gang drive for the control rods was unavailable.
range 1. However, the reactor coolant system continued to cool down because


This made the reactivity
the normal steam system loads were removing heat. In order not to affect the


insertion
source range monitor surveillance, the shift supervisor elected to not insert


slower than normal. The operators
control rods and alerted the operators to the possibility of a return to


inserted rods to reduce flux to range 3 on the IRMs and stopped rod insertion
criticality as the cooldown continued. The reactivity added by the cooldown


in order to perform a source range monitor surveillance.
eventually overcame the effects of the control rods. The reactor returned to a


Indicated
critical condition, and reactor power increased on a reactor period between 300
to 800 seconds. The operators, having been trained on a similar event at


power reached IRM range 1. However, the reactor coolant system continued
another BWR, were monitoring the condition and expected the power to increase


to cool down because the normal steam system loads were removing heat. In order not to affect the source range monitor surveillance, the shift supervisor
to the point of adding heat, where the fuel and moderator temperature coeffi- cients would halt the reactor power increase. As the power increased, the


elected to not insert control rods and alerted the operators
IN 92-39 May 13, 1992 reactor operator ranged the IRMs to prevent a reactor scram. Power level


to the possibility
remained on scale. The power increase was terminated with the IRMs reading on


of a return to criticality
range 7 and 8. The operators completed the source range monitor surveillance, then resumed inserting rods and successfully completed the shutdown.


as the cooldown continued.
Further details of the event may be found in NRC Inspection Report


The reactivity
50-416/92-04 and Licensee Event Report 50-416/91-16.
 
added by the cooldown eventually
 
overcame the effects of the control rods. The reactor returned to a critical condition, and reactor power increased
 
on a reactor period between 300 to 800 seconds. The operators, having been trained on a similar event at another BWR, were monitoring
 
the condition
 
and expected the power to increase to the point of adding heat, where the fuel and moderator
 
temperature
 
coeffi-cients would halt the reactor power increase.
 
As the power increased, the
 
IN 92-39 May 13, 1992 reactor operator ranged the IRMs to prevent a reactor scram. Power level remained on scale. The power increase was terminated
 
with the IRMs reading on range 7 and 8. The operators
 
completed
 
the source range monitor surveillance, then resumed inserting
 
rods and successfully
 
completed
 
the shutdown.Further details of the event may be found in NRC Inspection
 
Report 50-416/92-04 and Licensee Event Report 50-416/91-16.


Discussion
Discussion


The underlying
The underlying principle of reactivity management is to maintain the reactor


principle
in the desired condition by properly anticipating, controlling, and responding


of reactivity
to the plant's changing parameters. The experience at Monticello, Big Rock


management
Point, and Grand Gulf indicates that shutdowns in situations with low decay


is to maintain the reactor in the desired condition
heat present a unique challenge to reactivity control if inadvertent recritica- lity is to be prevented. These events emphasize the importance of the operator


by properly anticipating, controlling, and responding
giving continuous attention to plant parameters during a shutdown. Further, accepting recriticality without prior management approval and procedures, i.e.,
an ad-hoc approach, raises concerns due to the lack of opportunity for contin- gency planning.


to the plant's changing parameters.
This information notice requires no specific action or written response. If


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


at Monticello, Big Rock Point, and Grand Gulf indicates
one of the technical contacts listed below or the appropriate Office of


that shutdowns
Nuclear Reactor Regulation (NRR) project manager.


in situations
Va&res'E.Rossi, Director


with low decay heat present a unique challenge
Division of Operational Events Assessment


to reactivity
Office of Nuclear Reactor Regulation


control if inadvertent
Technical contacts: Melvyn Leach, RIII


recritica- lity is to be prevented.
(708) 790-5559 Geoffrey Wright, RIII


These events emphasize
(708) 790-5695 Paul O'Connor, NRR


the importance
(301) 504-1307 Attachment:  List of Recently Issued NRC Information Notices


of the operator giving continuous
z


attention
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to plant parameters
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LIST OF RECENTLY ISSUED


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about the information
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in this notice, please contact one of the technical
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contacts listed below or the appropriate
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0                      92-38            Implementation Date for        05/12/92  All holders of OLs or CPs


Office of Nuclear Reactor Regulation (NRR) project manager.Va&res'E.Rossi, Director Division of Operational
the Revision to the EPA                    for nuclear power reactors, Manual of Protective                      non-power reactors and


===Events Assessment===
Action Guides and Pro-                    materials licensees auth- tective Actions for                        orized to possess large
Office of Nuclear Reactor Regulation


Technical
Nuclear Incidents                          quantities of radioactive


contacts:
material.
Melvyn Leach, RIII (708) 790-5559 Geoffrey Wright, RIII (708) 790-5695 Paul O'Connor, NRR (301) 504-1307 Attachment:
List of Recently Issued NRC Information


Notices
1 92-37            Implementation of the          05/08/92  All Nuclear Regulatory


z I-0.<OD n; co> 0 m Z.4-m rn o 0 0 z Z G2-cn a En z* om o) Z en q-n M 0n a 0 n a -h <-Attachment
Deliberate Nisconduct Rule                  Commission Licensees.


1 IN 92-39 May 13, 1992 Page I of 1 LIST OF RECENTLY ISSUED NRC INFORMATION
92-16,           Loss of Flow from the Re-        05/07/92  All holders of OLs or CPs


===NOTICES Date of Information===
Supp. 1          sidual Heat Removal Pump                  for nuclear power reactors.
information


Notice No.92-38 1 92-37 92-16, Supp. 1 I 92-36' 92-35 Subject Implementation
during Refueling Cavity


Date for the Revision to the EPA Manual of Protective
Draindown


Action Guides and Pro-tective Actions for Nuclear Incidents Implementation
I 92-36            Intersystem LOCA Outside        05/07/92  All holders of OLs or CPs


of the Deliberate
Containment                                for nuclear power reactors.


Nisconduct
' 92-35            Higher Than Predicted Ero-      05/06/92  All holders of OLs or CPs


Rule Loss of Flow from the Re-sidual Heat Removal Pump during Refueling
sion/Corrosion in Unisol-                 for nuclear power reactors.


Cavity Draindown Intersystem
able Reactor Coolant Pres- sure Boundary Piping Inside


===LOCA Outside Containment===
Containment at A Boiling
Higher Than Predicted


Ero-sion/Corrosion
Water Reactor


in Unisol-able Reactor Coolant Pres-sure Boundary Piping Inside Containment
92-34            New Exposure Limits for


at A Boiling Water Reactor New Exposure Limits for Airborne Uranium and Thorium Increased
Airborne Uranium and


Instrument
Thorium


Response Time When Pressure Dampening Devices are Installed Issuance 05/12/92 05/08/92 05/07/92 05/07/92 05/06/92 Issued to All holders of OLs or CPs for nuclear power reactors, non-power
05/06/92 All licensees whose opera- tions can cause airborne


reactors and materials
concentrations of uranium


licensees
(
                                                                                    and thorium.


auth-orized to possess large quantities
92-33          Increased Instrument            04/30/92  All holders of OLs or CPs


of radioactive
-u                      Response Time When                        for nuclear power reactors.


material.All Nuclear Regulatory
0                        Pressure Dampening


Commission
rn>                          Devices are Installed


Licensees.
mD


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.-u 0 rn>mD-C > 0 u) D-D2 zzz>0 92-34 92-33 I CP -'05/06/92 All licensees
- C > 0
                D2 zzz>                 Operating License


whose opera-tions can cause airborne concentrations
u) D-   I CP - 'Construction Permit


of uranium and thorium.04/30/92 All holders of OLs or CPs for nuclear power reactors.(Operating
0


License Construction
IN 92-39 May 13, 1992 reactor operator ranged the IRMs to prevent a reactor scram. Power level


Permit
remained on scale. The power increase was terminated with the IRMs reading on


IN 92-39 May 13, 1992 reactor operator ranged the IRMs to prevent a reactor scram. Power level remained on scale. The power increase was terminated
range 7 and 8. The operators completed the source range monitor surveillance, then resumed inserting rods and successfully completed the shutdown.


with the IRMs reading on range 7 and 8. The operators
Further details of the event may be found in NRC Inspection Report


completed
50-416/92-04 and Licensee Event Report 50-416/91-16.
 
the source range monitor surveillance, then resumed inserting
 
rods and successfully
 
completed
 
the shutdown.Further details of the event may be found in NRC Inspection
 
Report 50-416/92-04 and Licensee Event Report 50-416/91-16.


Discussion
Discussion


The underlying
The underlying principle of reactivity management is to maintain the reactor


principle
in the desired condition by properly anticipating, controlling, and responding


of reactivity
to the plant's changing parameters. The experience at Monticello, Big Rock


management
Point, and Grand Gulf indicates that shutdowns in situations with low decay


is to maintain the reactor in the desired condition
heat present a unique challenge to reactivity control if inadvertent recritica- lity is to be prevented. These events emphasize the importance of the operator


by properly anticipating, controlling, and responding
giving continuous attention to plant parameters during a shutdown. Further, accepting recriticality without prior management approval and procedures, i.e.,
          an ad-hoc approach, raises concerns due to the lack of opportunity for contin- gency planning.


to the plant's changing parameters.
This information notice requires no specific action or written response. If


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


at Monticello, Big Rock Point, and Grand Gulf indicates
one of the technical contacts listed below or the appropriate Office of


that shutdowns
Nuclear Reactor Regulation (NRR) project manager. Original Signed by


in situations
Nhedes E, Rossi


with low decay heat present a unique challenge
Charles E. Rossi, Director


to reactivity
Division of Operational Events Assessment


control if inadvertent
Office of Nuclear Reactor Regulation


recritica- lity is to be prevented.
Technical contacts:  Melvyn Leach, RIII


These events emphasize
(708) 790-5559 Geoffrey Wright, RIII


the importance
(708) 790-5695 Paul O'Connor, NRR


of the operator giving continuous
(301) 504-1307 Attachment:  List of Recently Issued NRC Information Notices


attention
*SEE PREVIOUS CONCURRENCE


to plant parameters
OFC  RIII        ADR4-5:PD4-1    SC:DOEA:OEAB    ADM:RPB    C:DST:SRXB      C:DOEA:OEAB


during a shutdown.
NAME  GWright*    PO'Connor*      RDennig*        JMain*    RJones*          AChaffee*
DATE  03/11/92    03/17/92        03/11/92        03/11/92  03/13/92        04/13/92 OFC  C:DOEA:OGCB      D        X,
NAME  CBerlinger*
DATE  04/21/92        05/ 7/92 DOCUMENT NAME:  IN 92-39


Further, accepting
IN 92-XX


recriticality
April xx, 1992 Further details of the event may be found in NRC Inspection Report


without prior management
50-416/92-04 and Licensee Event Report 50-416/91-16.


approval and procedures, i.e., an ad-hoc approach, raises concerns due to the lack of opportunity
Discussion


for contin-gency planning.This information
The underlying principle of reactivity management is to maintain the reactor


notice requires no specific action or written response.
in the desired condition by properly anticipating, controlling, and responding


If you have any questions
to the plant's changing parameters. The experience at Big Rock Point, Grand


about the information
Gulf, and Monticello indicates that shutdowns in situations with low decay heat


in this notice, please contact one of the technical
present a unique challenge to reactivity control if inadvertent recriticality


contacts listed below or the appropriate
is to be prevented. These events emphasize the importance of the operator


Office of Nuclear Reactor Regulation (NRR) project manager. Original Signed by Nhedes E, Rossi Charles E. Rossi, Director Division of Operational
giving continuous attention to plant parameters during a shutdown. Further, accepting recriticality without prior management approval and procedures, i.e.,
          an ad-hoc approach, raises concerns due to the lack of opportunity for contin- gency planning.


===Events Assessment===
This information notice requires no specific action or written response. If
Office of Nuclear Reactor Regulation


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


contacts:
one of the technical contacts listed below or the appropriate Office of
Melvyn Leach, RIII (708) 790-5559 Geoffrey Wright, RIII (708) 790-5695 Paul O'Connor, NRR (301) 504-1307 Attachment:
List of Recently Issued NRC Information


Notices*SEE PREVIOUS CONCURRENCE
Nuclear Reactor Regulation (NRR) project manager.


OFC RIII ADR4-5:PD4-1 SC:DOEA:OEAB
Charles E. Rossi, Director


ADM:RPB C:DST:SRXB
Division of Operational Events Assessment


C:DOEA:OEAB
Office of Nuclear Reactor Regulation


NAME GWright* PO'Connor*
Technical contacts:   Melvyn Leach, RIII
RDennig* JMain* RJones* AChaffee*DATE 03/11/92 03/17/92 03/11/92 03/11/92 03/13/92 04/13/92 OFC C:DOEA:OGCB


D X, NAME CBerlinger*
(708) 790-5559 Geoffrey Wright, RIII
DATE 04/21/92 05/ 7/92 DOCUMENT NAME: IN 92-39 IN 92-XX April xx, 1992 Further details of the event may be found in NRC Inspection


Report 50-416/92-04 and Licensee Event Report 50-416/91-16.
(708) 790-5695 Paul O'Connor, NRR


Discussion
(301) 504-1307 Attachment:  List of Recently Issued NRC Information Notices


The underlying
*SEE PREVIOUS CONCURRENCE


principle
OFC  RIII        ADR4-5:PD4-1    SC:DOEA:OEAB    ADM:RPB    C:DST:SRXB    C:DOEA:OEAB


of reactivity
NAME  GWright*    PO'Connor*      RDennig*        JMain*    RJones*      AChaffee*
DATE  03/11/92    03/17/92        03/11/92        03/11/92  03/13/92      04/13/92 OFC  C:DOEA:OGCB      D:DOEA


management
NAME  CBerlinger*      CRoss tD


is to maintain the reactor in the desired condition
DATE  04/21/92              /9 OFFICIAL RECORD COPY                          DOCUMENT NAME:  IN DENKIG


by properly anticipating, controlling, and responding
IN 92-XX


to the plant's changing parameters.
April xx, 1992 Further details of the event may be found in NRC Inspection Report


The experience
50-416/92-04 and Licensee Event Report 50-416/91-16.


at Big Rock Point, Grand Gulf, and Monticello
Discussion


indicates
The underlying principle of reactivity management is to maintain the reactor


that shutdowns
in the desired condition by properly anticipating, controlling, and responding


in situations
to the plant's changing parameters. Once a reactor has been placed in a


with low decay heat present a unique challenge
subcritical condition during a plant shutdown, it is of primary importance


to reactivity
that the reactor be maintained in that subcritical condition. Raising the


control if inadvertent
range of the IRMs in the event of recriticality can be inappropriate if the


recriticality
licensed operators do not have management's oversight, training, and specific


is to be prevented.
procedures for this.


These events emphasize
The experience at Grand Gulf and Monticello indicate that slow shutdowns in


the importance
situations with low decay heat present a unique challenge to reactivity


of the operator giving continuous
control and require the operator and management to give careful attention to


attention
avoid recriticality. The events at Monticello and Big Rock Point also highlight


to plant parameters
the importance of the operator giving continuous attention to plant parameters


during a shutdown.
during a shutdown.


Further, accepting
This information notice requires no specific action or written response. If


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


without prior management
one of the technical contacts listed below or the appropriate Office of


approval and procedures, i.e., an ad-hoc approach, raises concerns due to the lack of opportunity
Nuclear Reactor Regulation (NRR) project manager.


for contin-gency planning.This information
Charles E. Rossi, Director


notice requires no specific action or written response.
Division of Operational Events Assessment


If you have any questions
Office of Nuclear Reactor Regulation
 
about the information
 
in this notice, please contact one of the technical


contacts listed below or the appropriate
Technical contacts:  Melvyn Leach, RIII


Office of Nuclear Reactor Regulation (NRR) project manager.Charles E. Rossi, Director Division of Operational
(708) 790-5559 Geoffrey Wright, RIII


===Events Assessment===
(708) 790-5695 Paul O'Connor, NRR
Office of Nuclear Reactor Regulation


Technical
(301) 504-1307 Attachment:  List of Recently Issued NRC Information Notices


contacts:
*SEE PREVIOUS CONCURRENCE
Melvyn Leach, RIII (708) 790-5559 Geoffrey Wright, RIII (708) 790-5695 Paul O'Connor, NRR (301) 504-1307 Attachment:
List of Recently Issued NRC Information


Notices*SEE PREVIOUS CONCURRENCE
OFC  RIII        ADR4-5:PD4-1  SC:DOEA:OEAB    ADM:RPB    C:DST:SRXB  C:DOEA:OEAB


OFC RIII ADR4-5:PD4-1 SC:DOEA:OEAB
NAME  GWright*    PO'Connor*    RDennig*        JMain*      RJones*    AChaffee*
DATE  03/11/92    03/17/92      03/11/92        03/11/92    03/13/92    04/13/92 OFC   C:DO      J


ADM:RPB C:DST:SRXB
f    D:DOEA


C:DOEA:OEAB
NAME  CBerlinger      CRosswa'y


NAME GWright* PO'Connor*
DATE   f/;11/ 92         / 92 OFFICIAL RECORD COPY                          DOCUMENT NAME:   IN DENNIG
RDennig* JMain* RJones* AChaffee*DATE 03/11/92 03/17/92 03/11/92 03/11/92 03/13/92 04/13/92 OFC C:DOEA:OGCB


D:DOEA NAME CBerlinger*
IN 92-XX
CRoss tD DATE 04/21/92 /9 OFFICIAL RECORD COPY DOCUMENT NAME: IN DENKIG


IN 92-XX April xx, 1992 Further details of the event may be found in NRC Inspection
March xx, 1992 Further details of the event may be found in NRC Inspection Report


Report 50-416/92-04 and Licensee Event Report 50-416/91-16.
50-416/92-04 and Licensee Event Report 50-416/91-16.


Discussion
Discussion


The underlying
The underlying principle of reactivity management is to maintain the reactor


principle
in the desired condition by properly anticipating, controlling, and responding


of reactivity
to the plant's changing parameters. Once a reactor has been placed in a


management
subcritical condition during a plant shutdown, it is of primary importance


is to maintain the reactor in the desired condition
that the reactor be maintained in that subcritical condition. In the event of


by properly anticipating, controlling, and responding
recriticality, promptly inserting control rods and terminating the cooldown are


to the plant's changing parameters.
more conservative actions than raising the range of the IRMs to prevent scram


Once a reactor has been placed in a subcritical
while waiting on the changing temperature to reverse the direction of the


condition
power. Raising the range of the IRMs in the event of recriticality can be


during a plant shutdown, it is of primary importance
inappropriate if the licensed operators do not have management's oversight, training, and specific procedures.


that the reactor be maintained
The experience at Grand Gulf and Monticello indicate that slow shutdowns in


in that subcritical
situations with low decay heat present a unique challenge to reactivity


condition.
control and require the operator and management to give careful attention to


Raising the range of the IRMs in the event of recriticality
avoid recriticality. The events at Monticello and Big Rock Point also highlight


can be inappropriate
the importance of the operator giving continuous attention to plant parameters


if the licensed operators
during a shutdown.


do not have management's
This information notice requires no specific action or written response. If


oversight, training, and specific procedures
you have any questions about the information in this notice, please contact


for this.The experience
one of the technical contacts listed below or the appropriate Office of


at Grand Gulf and Monticello
Nuclear Reactor Regulation (NRR) project manager.


indicate that slow shutdowns
Charles E. Rossi, Director


in situations
Division of Operational Events Assessment


with low decay heat present a unique challenge
Office of Nuclear Reactor Regulation
 
to reactivity
 
control and require the operator and management
 
to give careful attention
 
to avoid recriticality.
 
The events at Monticello
 
and Big Rock Point also highlight the importance
 
of the operator giving continuous
 
attention
 
to plant parameters
 
during a shutdown.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
Technical contacts:  Melvyn Leach, RIII


Office of Nuclear Reactor Regulation (NRR) project manager.Charles E. Rossi, Director Division of Operational
(708) 790-5559 Geoffrey Wright, RIII


===Events Assessment===
(708) 790-5695 Paul O'Connor, NRR
Office of Nuclear Reactor Regulation


Technical
(301) 504-1307 t'/ '      f'      4.f, IV


contacts:
Attachment:   List of Recently Issued NRC Information Notices
Melvyn Leach, RIII (708) 790-5559 Geoffrey Wright, RIII (708) 790-5695 Paul O'Connor, NRR (301) 504-1307 Attachment:  
List of Recently Issued NRC Information


Notices*SEE PREVIOUS CONCURRENCE
*SEE PREVIOUS CONCURRENCEC


OFC RIII ADR4-5:PD4-1 SC:DOEA:OEAB
OFC   RIII         ADR4-5:PD4-1   SC:DOEA:OEAB    ADM:RPB    C:DST:SRXB  C:D0EA:OEAB


ADM:RPB C:DST:SRXB
NAME  GWright*    PO'Connor*    RDennig*        JMain*    RJones*      AChaffee


C:DOEA:OEAB
DATE 03/11/92      03/17/92      03/11/92        03/11/92  03/13/92      q1/t3/92 OFC  C:DOEA:OGCB      D:DOEA


NAME GWright* PO'Connor*
===NAME CBerlinger      CRossi===
RDennig* JMain* RJones* AChaffee*DATE 03/11/92 03/17/92 03/11/92 03/11/92 03/13/92 04/13/92 OFC C:DO J f D:DOEA NAME CBerlinger
DATE   / /92           / /92 OFFICIAL RECORD COPY                          DOCUMENT NAME:   IN DENNIG


CRosswa'y DATE f/;11/9 2/ 92 OFFICIAL RECORD COPY DOCUMENT NAME: IN DENNIG
IN 92-XX


IN 92-XX March xx, 1992 Further details of the event may be found in NRC Inspection
March xx, 1992 Further details of the event may be found in NRC Inspection Report


Report 50-416/92-04 and Licensee Event Report 50-416/91-16.
50-416/92-04 and Licensee Event Report 50-416/91-16.


Discussion
Discussion


The underlying
The underlying principle of reactivity management is to maintain the reactor


principle
in the desired condition by properly anticipating, controlling, and responding


of reactivity
to the plant's changing parameters. Once a reactor has been placed in a


management
subcritical condition during a plant shutdown, it is of primary importance


is to maintain the reactor in the desired condition
that the reactor be maintained in that subcritical condition. In the event of


by properly anticipating, controlling, and responding
recriticality, promptly inserting control rods and terminating the cooldown are


to the plant's changing parameters.
more conservative actions than raising the range of the IRMs to prevent scram


Once a reactor has been placed in a subcritical
while waiting on the changing temperature to reverse the direction of the


condition
power. Raising the range of the IRMs in the event of recriticality can be


during a plant shutdown, it is of primary importance
inappropriate if the licensed operators do not have management's oversight, training, and specific procedures.


that the reactor be maintained
The experience at Grand Gulf and Monticello indicate that slow shutdowns in


in that subcritical
situations with low decay heat present a unique challenge to reactivity


condition.
control and require the operator and management to give careful attention to


In the event of recriticality, promptly inserting
avoid recriticality. The events at Monticello and Big Rock Point also highlight


control rods and terminating
the importance of the operator giving continuous attention to plant parameters


the cooldown are more conservative
during a shutdown.
 
actions than raising the range of the IRMs to prevent scram while waiting on the changing temperature
 
to reverse the direction


of the power. Raising the range of the IRMs in the event of recriticality
This information notice requires no specific action or written response. If


can be inappropriate
you have any questions about the information in this notice, please contact


if the licensed operators
one of the technical contacts listed below or the appropriate Office of


do not have management's
Nuclear Reactor Regulation (NRR) project manager.


oversight, training, and specific procedures.
Charles E. Rossi, Director


The experience
Division of Operational Events Assessment


at Grand Gulf and Monticello
indicate that slow shutdowns
in situations
with low decay heat present a unique challenge
to reactivity
control and require the operator and management
to give careful attention
to avoid recriticality.
The events at Monticello
and Big Rock Point also highlight the importance
of the operator giving continuous
attention
to plant parameters
during a shutdown.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.Charles E. Rossi, Director Division of Operational
===Events Assessment===
Office of Nuclear Reactor Regulation
Office of Nuclear Reactor Regulation


Technical
Technical contacts:   Melvyn Leach, RIII
 
contacts:  
Melvyn Leach, RIII (708) 790-5559 Geoffrey Wright, RIII (708) 790-5695 Paul O'Connor, NRR IV t'/ ' f'(301) 504-1307 4.f, Attachment:
List of Recently Issued NRC Information
 
Notices*SEE PREVIOUS CONCURRENCEC
 
OFC RIII ADR4-5:PD4-1 SC:DOEA:OEAB
 
ADM:RPB C:DST:SRXB
 
C:D0EA:OEAB
 
NAME GWright* PO'Connor*
RDennig* JMain* RJones* AChaffee DATE 03/11/92 03/17/92 03/11/92 03/11/92 03/13/92 q1/t3/92 OFC C:DOEA:OGCB
 
D:DOEA NAME CBerlinger
 
CRossi DATE / /92 / /92 OFFICIAL RECORD COPY DOCUMENT NAME: IN DENNIG
 
IN 92-XX March xx, 1992 Further details of the event may be found in NRC Inspection
 
Report 50-416/92-04 and Licensee Event Report 50-416/91-16.
 
Discussion
 
The underlying
 
principle
 
of reactivity
 
management
 
is to maintain the reactor in the desired condition
 
by properly anticipating, controlling, and responding
 
to the plant's changing parameters.
 
Once a reactor has been placed in a subcritical
 
condition
 
during a plant shutdown, it is of primary importance
 
that the reactor be maintained
 
in that subcritical
 
condition.
 
In the event of recriticality, promptly inserting
 
control rods and terminating
 
the cooldown are more conservative
 
actions than raising the range of the IRMs to prevent scram while waiting on the changing temperature
 
to reverse the direction
 
of the power. Raising the range of the IRMs in the event of recriticality
 
can be inappropriate
 
if the licensed operators
 
do not have management's
 
oversight, training, and specific procedures.
 
The experience
 
at Grand Gulf and Monticello


indicate that slow shutdowns
(708) 790-5559 Geoffrey Wright, 'RIII


in situations
(708) 790-5695 Paul O'Connor, NRR


with low decay heat present a unique challenge
(301) 504-1307 Attachment:  List of Recently Issued NRC Information Notices


to reactivity
*SEE PREVIOUS CONCURRENCE


control and require the operator and management
OFC  RIII        ADR4-5:PD4-1    SC:DOEA:OEAB    ADM:RPB    C:DST:SRXB  C:DOEA:OEAB


to give careful attention
NAME GWright*    PO'Connor (OK RDennig*          JMain*    RJones*      AChaffee


to avoid recriticality.
DATE 03/11/92    3 /17/92  Xis    192          03/11/92  03/13/92      /  /92 OFC  C:DOEA:OGCB      D:DOEA


The events at Monticello
===NAME CBerlinger      CRossi===
DATE  / /92            / /92


and Big Rock Point also highlight the importance
IN 92-XX


of the operator giving continuous
March xx, 1992 Further details of the event may be found in NRC Inspection Report


attention
50-416/92-04 and Licensee Event Report 50-416/91-16.
 
to plant parameters
 
during a shutdown.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.Charles E. Rossi, Director Division of Operational
 
===Events Assessment===
Office of Nuclear Reactor Regulation
 
Technical
 
contacts:
Melvyn Leach, RIII (708) 790-5559 Geoffrey Wright, 'RIII (708) 790-5695 Paul O'Connor, NRR (301) 504-1307 Attachment:
List of Recently Issued NRC Information
 
Notices*SEE PREVIOUS CONCURRENCE
 
OFC RIII ADR4-5:PD4-1 SC:DOEA:OEAB
 
ADM:RPB C:DST:SRXB
 
C:DOEA:OEAB
 
NAME GWright* PO'Connor (OK RDennig* JMain* RJones* AChaffee DATE 03/11/92 3 /17/92 Xis 192 03/11/92 03/13/92 / /92 OFC C:DOEA:OGCB
 
D:DOEA NAME CBerlinger
 
CRossi DATE / /92 / /92 IN 92-XX March xx, 1992 Further details of the event may be found in NRC Inspection
 
Report 50-416/92-04 and Licensee Event Report 50-416/91-16.


Discussion
Discussion


The underlying
The underlying principle of reactivity management is to maintain the reactor


principle
in the desired condition by properly anticipating, controlling, and responding


of reactivity
to the plant's changing parameters. Once a reactor has been placed in a


management
subcritical condition during a plant shutdown, it is of primary importance


is to maintain the reactor in the desired condition
that the reactor be maintained in that subcritical condition. Since recriti- cality has not been avoided, promptly inserting control rods and terminating


by properly anticipating, controlling, and responding
the cooldown are more conservative actions than raising the range of the IRMs


to the plant's changing parameters.
to prevent scram while waiting on the changing temperature to reverse the


Once a reactor has been placed in a subcritical
direction of the power. Raising the range of the IRMs in the event of recriti- cality can be inappropriate if the licensed operators do not have management's
 
condition
 
during a plant shutdown, it is of primary importance
 
that the reactor be maintained
 
in that subcritical
 
condition.
 
Since recriti-cality has not been avoided, promptly inserting
 
control rods and terminating
 
the cooldown are more conservative
 
actions than raising the range of the IRMs to prevent scram while waiting on the changing temperature
 
to reverse the direction
 
of the power. Raising the range of the IRMs in the event of recriti-cality can be inappropriate
 
if the licensed operators
 
do not have management's


oversight, training, and specific procedures.
oversight, training, and specific procedures.


The experience
The experience at Grand Gulf and Monticello indicate that slow shutdowns in


at Grand Gulf and Monticello
situations with low decay heat present a unique challenge to reactivity


indicate that slow shutdowns
control and require the operator and management to give careful attention to


in situations
avoid recriticality. The events at Monticello and Big Rock Point also highlight


with low decay heat present a unique challenge
the importance of the operator giving continuous attention to plant parameters


to reactivity
during a shutdown.
 
control and require the operator and management
 
to give careful attention
 
to avoid recriticality.
 
The events at Monticello
 
and Big Rock Point also highlight the importance
 
of the operator giving continuous
 
attention
 
to plant parameters
 
during a shutdown.This information


notice requires no specific action or written response.
This information notice requires no specific action or written response. If


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


about the information
one of the technical contacts listed below or the appropriate Office of


in this notice, please contact one of the technical
Nuclear Reactor Regulation (NRR) project manager.


contacts listed below or the appropriate
Charles E. Rossi, Director


Office of Nuclear Reactor Regulation (NRR) project manager.Charles E. Rossi, Director Division of Operational
Division of Operational Events Assessment


===Events Assessment===
Office of Nuclear Reactor Regulation
Office of Nuclear Reactor Regulation


Technical
Technical contacts:           Melvyn Leach, RIII
 
contacts:  
Melvyn Leach, RIII (708) 790-5559 Geoffrey Wright, RII (708) 790-5695 Paul O'Connor, NRR (301) 504-1307 Attachment:
List of Recently Issued NRC Information


Notices*SEE PREVIOUS CONCURRENCE
(708) 790-5559 Geoffrey Wright, RII


OFC :RIII :S Oq;:EfAB:ADM:RPB
(708) 790-5695 Paul O'Connor, NRR


:C:D B :C:DOEA:OEAB
(301) 504-1307 Attachment:         List of Recently Issued NRC Information Notices


:C:DOEA:OGCB
*SEE PREVIOUS CONCURRENCE


:D:DOEA-____ _ _________----
OFC  :RIII        :S              Oq;:EfAB:ADM:RPB        :C:D     B  :C:DOEA:OEAB :C:DOEA:OGCB :D:DOEA
_ --____________
----_ -:---------------
NAME :GWright*
:Rbennig :JMain* j Jones :AChaffee


:CBerlinger
____
            _    _________----_          -- ____________                ----  _  -:---------------
NAME :GWright*    :Rbennig              :JMain*          j  Jones      :AChaffee      :CBerlinger           :CRossi


:CRossi DATE :03/11/92  
DATE :03/11/92     :3 /11/92             :03/11/92         : /13/92     : / /92         : / /92               : / /92 OFFICIAL RECORD COPY
:3 /11/92 :03/11/92  
: /13/92 : / /92 : / /92 : / /92 OFFICIAL RECORD COPY Document Name: IN DENNIG


Further details of the event may be found in NRC Inspection
Document Name: IN DENNIG


Report 50-416/92-04 and Licensee Event Report 50-416/91-16.
Further details of the event may be found in NRC Inspection Report 50-416/92-04 and Licensee Event Report 50-416/91-16.


Discussion
Discussion


The underlying
The underlying principle of reactivity management is to maintain the reactor in
 
principle
 
of reactivity
 
management
 
is to maintain the reactor in the desired condition
 
by properly anticipating, controlling, and responding
 
to the plant's changing parameters.
 
Once a reactor has been placed in a subcritical
 
condition, as part of a plant shutdown, it is of primary importance
 
that the reactor be maintained
 
in that subcritical
 
condition.
 
Given that recriticality
 
has not been avoided, prompt insertion
 
of control rods and termination
 
of the cooldown are more conservative


actions than upranging
the desired condition by properly anticipating, controlling, and responding to


IRMs to prevent scram while waiting on temperature
the plant's changing parameters. Once a reactor has been placed in a


coefficients
subcritical condition, as part of a plant shutdown, it is of primary importance


to turn power.Upranging
that the reactor be maintained in that subcritical condition. Given that


IRMs in the event of recriticality
recriticality has not been avoided, prompt insertion of control rods and


can be inappropriate
termination of the cooldown are more conservative actions than upranging IRMs


if management
to prevent scram while waiting on temperature coefficients to turn power.


oversight, prior training, and specific procedures
Upranging IRMs in the event of recriticality can be inappropriate if management


are absent.The experience
oversight, prior training, and specific procedures are absent.


at Grand Gulf and Monticello
The experience at Grand Gulf and Monticello indicate that slow shutdowns in


indicate that slow shutdowns
situations with low decay heat present a particular challenge to reactivity


in situations
control, and require heightened operator and management awareness to avoid


with low decay heat present a particular
recriticality. In addition, the events at Monticello and Big Rock Point


challenge
highlight the importance of continuous operator attention to plant parameters


to reactivity
in the course of a shutdown.


control, and require heightened
This information notice requires  no specific action or written response. If


operator and management
you have any questions about the  information in this notice, please contact one


awareness
of the technical contacts listed  below or the appropriate Office of Nuclear


to avoid recriticality.
Reactor Regulation (NRR) project  manager.


In addition, the events at Monticello
Charles E. Rossi, Director


and Big Rock Point highlight
Division of Operational Events Assessment


the importance
of continuous
operator attention
to plant parameters
in the course of a shutdown.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.Charles E. Rossi, Director Division of Operational
===Events Assessment===
Office of Nuclear Reactor Regulation
Office of Nuclear Reactor Regulation


Technical
Technical contacts:  Melvyn Leach, RIII


contacts:
(708) 790-5559 Geoffrey Wright, RIII
Melvyn Leach, RIII (708) 790-5559 Geoffrey Wright, RIII (708) 790-5695 Paul O'Connor, NRR (301) 504-1307 Attachment:
List of Recently Issued NRC Information


Notices OFC :RIII :SC:DOEA:OEAB:ADM:RPB
(708) 790-5695 Paul O'Connor, NRR


:C:DST:SRXB
(301) 504-1307 Attachment:   List of Recently Issued NRC Information Notices


:C:DOEA:OEAB
OFC  :RIII          :SC:DOEA:OEAB:ADM:RPB    :C:DST:SRXB  :C:DOEA:OEAB :C:DOEA:OGCB :D:DOEA


:C:DOEA:OGCB
NAME :GWright      :RDennig    :JMain_ w    :RJones      :AChaffee    :CBerlinger  :CRossi


:D:DOEA NAME :GWright :RDennig :JMain_ w :RJones :AChaffee
DATE ://92          :1/92        :3/11 /92    :1/92        ://92        :1    /92    :/    /92 OFFICIAL RECORD COPY


:CBerlinger
Document Name: IN DENNIG/DUP


:CRossi DATE ://92 :1/92 :3/11 /92 :1/92 ://92 :1 /92 :/ /92 OFFICIAL RECORD COPY Document Name: IN DENNIG/DUP
IN 92-XX


IN 92-XX March xx, 1992 Further details of the event may be found in NRC Inspection
March xx, 1992 Further details of the event may be found in NRC Inspection Report


Report 50-416/92-04 and Licensee Event Report 50-416/91-16.
50-416/92-04 and Licensee Event Report 50-416/91-16.


Discussion
Discussion


The underlying
The underlying principle of reactivity management is to maintain the reactor
 
principle
 
of reactivity
 
management
 
is to maintain the reactor in the desired condition


by properly anticipating, controlling, and responding
in the desired condition by properly anticipating, controlling, and responding


to the plant's changing parameters.
to the plant's changing parameters. Once a reactor has been placed in a


Once a reactor has been placed in a subcritical
subcritical condition, as part of a plant shutdown, it is of primary importance


condition, as part of a plant shutdown, it is of primary importance
that the reactor be maintained in that subcritical condition. Given that


that the reactor be maintained
recriticality has not been avoided, prompt insertion of control rods and


in that subcritical
termination of the cooldown are more conservative actions than upranging


condition.
IRMs to prevent scram while waiting on temperature coefficients to turn power.


Given that recriticality
Upranging IRMs in the event of recriticality can be inappropriate if management


has not been avoided, prompt insertion
oversight, prior training, and specific procedures are absent.


of control rods and termination
The experience at Grand Gulf and Monticello indicate that slow shutdowns in


of the cooldown are more conservative
situations with low decay heat present a particular challenge to reactivity


actions than upranging IRMs to prevent scram while waiting on temperature
control, and require heightened operator and management awareness to avoid


coefficients
recriticality. In addition, the events at Monticello and Big Rock Point


to turn power.Upranging
highlight the importance of continuous operator attention to plant parameters


IRMs in the event of recriticality
in the course of a shutdown.


can be inappropriate
This information notice requires no specific action or written response. If


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


oversight, prior training, and specific procedures
one of the technical contacts listed below or the appropriate Office of


are absent.The experience
Nuclear Reactor Regulation (NRR) project manager.


at Grand Gulf and Monticello
Charles E. Rossi, Director


indicate that slow shutdowns
Division of Operational Events Assessment


in situations
with low decay heat present a particular
challenge
to reactivity
control, and require heightened
operator and management
awareness
to avoid recriticality.
In addition, the events at Monticello
and Big Rock Point highlight
the importance
of continuous
operator attention
to plant parameters
in the course of a shutdown.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.Charles E. Rossi, Director Division of Operational
===Events Assessment===
Office of Nuclear Reactor Regulation
Office of Nuclear Reactor Regulation


Technical
Technical contacts: Melvyn Leach, RIII
 
contacts:  
Melvyn Leach, RIII (708) 790-5559 Geoffrey Wright, RIII (708) 790-5695 Paul O'Connor, NRR (301) 504-1307 Attachment:
List of Recently Issued NRC Information


Notices OFC :R111 bC:DOEA:OEAB:ADM:RPB
(708) 790-5559 Geoffrey Wright, RIII


:C:DST:SRXB
(708) 790-5695 Paul O'Connor, NRR


:C:DOEA:OEAB
(301) 504-1307 Attachment: List of Recently Issued NRC Information Notices


:C:DOEA:OGCB
OFC  :R111          bC:DOEA:OEAB:ADM:RPB      :C:DST:SRXB  :C:DOEA:OEAB :C:DOEA:OGCB :D:DOEA


:D:DOEA NAME :GWrightV'  
NAME :GWrightV' :RDennig         :JMain       :RJones       :AChaffee   :CBerlinger  :CRossi
:RDennig :JMain :RJones :AChaffee


:CBerlinger
DATE :3 /II/92      ://92        :/    /92  :/    /92    :/    /92    :/    /92    :/    /92 OFFICIAL RECORD COPY


:CRossi DATE :3 /II/92 ://92 :/ /92 :/ /92 :/ /92 :/ /92 :/ /92 OFFICIAL RECORD COPY Document Name: IN DENNIG}}
Document Name: IN DENNIG}}


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

Latest revision as of 03:22, 24 November 2019

Unplanned Return to Criticality During Reactor Shutdown
ML031200314
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: 05/13/1992
From: Rossi C
Office of Nuclear Reactor Regulation
To:
References
IN-92-039, NUDOCS 9205060036
Download: ML031200314 (12)


UNITED STATES

NUCLEAR REGULATORY COMMISSION

OFFICE OF NUCLEAR REACTOR REGULATION

WASHINGTON, D.C. 20555 May 13, 1992 NRC INFORMATION NOTICE 92-39: UNPLANNED RETURN TO CRITICALITY DURING

REACTOR SHUTDOWN

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 recent events involving unplanned returns to

criticality caused by the cooldown of the reactor coolant system during reactor

shutdowns. 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

The licensees for the following plants recently experienced unplanned

criticalities during reactor shutdowns: the Monticello Nuclear Generating

Plant, the Big Rock Point Nuclear Plant, and the Grand Gulf Nuclear Station.

Monticello

On June 6, 1991, an unplanned criticality occurred at the Monticello Nuclear

Generating Plant during a reactor shutdown when an unanticipated cooldown

occurred in conjunction with rod insertion. The licensee initiated this

shutdown to repair a leaking safety-relief valve shortly after the plant was

returning to power following a refueling outage.

Since this shutdown occurred shortly after the cycle startup, the reactor did

not generate sufficient decay heat to produce the steam needed to supply the

normal steam system loads and still maintain pressure in the reactor. As

control rods were being inserted using notch insertion, the reactor coolant

system pressure and temperature began to decrease. As long as the operator

continued to insert control rods, the reactor remained subcritical.

However, when the operator stopped inserting control rods to review and

evaluate plant conditions, the cooldown continued, adding sufficient

reactivity to overcome the negative reactivity from the insertion of control

rods and causing the reactor power to increase. The reactor power continued to

92050_*

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i / 1 ( / /CDQc

K)

IN 92-39 May 13, 1992 increase until an intermediate-range monitor (IRM) tripped on a high-high flux

setpoint, causing a reactor scram.

Further details of the event may be found in Licensee Event Report

50-263/91-15 or NRC Inspection Report 50-263/91-13.

Big Rock Point

On November 30, 1991, an unplanned criticality occurred at the Big Rock Point

Nuclear Plant during a reactor shutdown when a cooldown occurred in conjunction

with a rod insertion. The event occurred during a scheduled shutdown for a

refueling outage.

After taking the main turbine off line and bringing the reactor to a

subcritical condition, the licensee delayed actions to continue inserting

control rods while changing shifts. However, the reactor coolant system

continued to cool down because the normal steam system loads were removing

heat. The cooldown added sufficient reactivity to eventually overcome the

effects of the control rods, and the reactor returned critical. The operators

noticed the condition in approximately 2 minutes and took the appropriate

actions to return the reactor subcritical.

Further details of the event may be found in Licensee Event Report

50-155/91-OO9-orJNRC-Inspection-Report 50-155/91-25. _ _ _

Grand Gulf

On December 30, 1991, an unplanned criticality occurred at the Grand Gulf

Nuclear Station during a reactor shutdown when a cooldown occurred in

conjunction with a rod insertion. The event occurred during a scheduled

shutdown for a maintenance outage to replace a recirculation pump shaft. To

minimize the release of plated-out radioactive material from the fuel cladding

and channels to the reactor coolant system, a slow power reduction and a slow

cooldown were prescribed for this shutdown.

The slow power reduction and the effects of an earlier outage minimized reactor

decay heat and xenon peaking. The operators were driving rods into the core

individually because gang drive for the control rods was unavailable. This

made the reactivity insertion slower than normal. The operators inserted

rods to reduce flux to range 3 on the IRMs and stopped rod insertion in order

to perform a source range monitor surveillance. Indicated power reached IRM

range 1. However, the reactor coolant system continued to cool down because

the normal steam system loads were removing heat. In order not to affect the

source range monitor surveillance, the shift supervisor elected to not insert

control rods and alerted the operators to the possibility of a return to

criticality as the cooldown continued. The reactivity added by the cooldown

eventually overcame the effects of the control rods. The reactor returned to a

critical condition, and reactor power increased on a reactor period between 300

to 800 seconds. The operators, having been trained on a similar event at

another BWR, were monitoring the condition and expected the power to increase

to the point of adding heat, where the fuel and moderator temperature coeffi- cients would halt the reactor power increase. As the power increased, the

IN 92-39 May 13, 1992 reactor operator ranged the IRMs to prevent a reactor scram. Power level

remained on scale. The power increase was terminated with the IRMs reading on

range 7 and 8. The operators completed the source range monitor surveillance, then resumed inserting rods and successfully completed the shutdown.

Further details of the event may be found in NRC Inspection Report

50-416/92-04 and Licensee Event Report 50-416/91-16.

Discussion

The underlying principle of reactivity management is to maintain the reactor

in the desired condition by properly anticipating, controlling, and responding

to the plant's changing parameters. The experience at Monticello, Big Rock

Point, and Grand Gulf indicates that shutdowns in situations with low decay

heat present a unique challenge to reactivity control if inadvertent recritica- lity is to be prevented. These events emphasize the importance of the operator

giving continuous attention to plant parameters during a shutdown. Further, accepting recriticality without prior management approval and procedures, i.e.,

an ad-hoc approach, raises concerns due to the lack of opportunity for contin- gency planning.

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.

Va&res'E.Rossi, Director

Division of Operational Events Assessment

Office of Nuclear Reactor Regulation

Technical contacts: Melvyn Leach, RIII

(708) 790-5559 Geoffrey Wright, RIII

(708) 790-5695 Paul O'Connor, NRR

(301) 504-1307 Attachment: List of Recently Issued NRC Information Notices

z

z

Attachment 1 I-0

IN 92-39

.< Z G2 May 13, 1992 OD n Page I of 1

co
  • a

om

LIST OF RECENTLY ISSUED

>0 o) Z NRC INFORMATION NOTICES

Enenz q

m Z -n M Information

m 0n a

.4- information Date of

rn - 0 cn

n Notice No. Subject Issuance Issued to

o a -

0 h <-

0 92-38 Implementation Date for 05/12/92 All holders of OLs or CPs

the Revision to the EPA for nuclear power reactors, Manual of Protective non-power reactors and

Action Guides and Pro- materials licensees auth- tective Actions for orized to possess large

Nuclear Incidents quantities of radioactive

material.

1 92-37 Implementation of the 05/08/92 All Nuclear Regulatory

Deliberate Nisconduct Rule Commission Licensees.

92-16, Loss of Flow from the Re- 05/07/92 All holders of OLs or CPs

Supp. 1 sidual Heat Removal Pump for nuclear power reactors.

during Refueling Cavity

Draindown

I 92-36 Intersystem LOCA Outside 05/07/92 All holders of OLs or CPs

Containment for nuclear power reactors.

' 92-35 Higher Than Predicted Ero- 05/06/92 All holders of OLs or CPs

sion/Corrosion in Unisol- for nuclear power reactors.

able Reactor Coolant Pres- sure Boundary Piping Inside

Containment at A Boiling

Water Reactor

92-34 New Exposure Limits for

Airborne Uranium and

Thorium

05/06/92 All licensees whose opera- tions can cause airborne

concentrations of uranium

(

and thorium.

92-33 Increased Instrument 04/30/92 All holders of OLs or CPs

-u Response Time When for nuclear power reactors.

0 Pressure Dampening

rn> Devices are Installed

mD

- C > 0

D2 zzz> Operating License

u) D- I CP - 'Construction Permit

0

IN 92-39 May 13, 1992 reactor operator ranged the IRMs to prevent a reactor scram. Power level

remained on scale. The power increase was terminated with the IRMs reading on

range 7 and 8. The operators completed the source range monitor surveillance, then resumed inserting rods and successfully completed the shutdown.

Further details of the event may be found in NRC Inspection Report

50-416/92-04 and Licensee Event Report 50-416/91-16.

Discussion

The underlying principle of reactivity management is to maintain the reactor

in the desired condition by properly anticipating, controlling, and responding

to the plant's changing parameters. The experience at Monticello, Big Rock

Point, and Grand Gulf indicates that shutdowns in situations with low decay

heat present a unique challenge to reactivity control if inadvertent recritica- lity is to be prevented. These events emphasize the importance of the operator

giving continuous attention to plant parameters during a shutdown. Further, accepting recriticality without prior management approval and procedures, i.e.,

an ad-hoc approach, raises concerns due to the lack of opportunity for contin- gency planning.

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 Signed by

Nhedes E, Rossi

Charles E. Rossi, Director

Division of Operational Events Assessment

Office of Nuclear Reactor Regulation

Technical contacts: Melvyn Leach, RIII

(708) 790-5559 Geoffrey Wright, RIII

(708) 790-5695 Paul O'Connor, NRR

(301) 504-1307 Attachment: List of Recently Issued NRC Information Notices

  • SEE PREVIOUS CONCURRENCE

OFC RIII ADR4-5:PD4-1 SC:DOEA:OEAB ADM:RPB C:DST:SRXB C:DOEA:OEAB

NAME GWright* PO'Connor* RDennig* JMain* RJones* AChaffee*

DATE 03/11/92 03/17/92 03/11/92 03/11/92 03/13/92 04/13/92 OFC C:DOEA:OGCB D X,

NAME CBerlinger*

DATE 04/21/92 05/ 7/92 DOCUMENT NAME: IN 92-39

IN 92-XX

April xx, 1992 Further details of the event may be found in NRC Inspection Report

50-416/92-04 and Licensee Event Report 50-416/91-16.

Discussion

The underlying principle of reactivity management is to maintain the reactor

in the desired condition by properly anticipating, controlling, and responding

to the plant's changing parameters. The experience at Big Rock Point, Grand

Gulf, and Monticello indicates that shutdowns in situations with low decay heat

present a unique challenge to reactivity control if inadvertent recriticality

is to be prevented. These events emphasize the importance of the operator

giving continuous attention to plant parameters during a shutdown. Further, accepting recriticality without prior management approval and procedures, i.e.,

an ad-hoc approach, raises concerns due to the lack of opportunity for contin- gency planning.

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.

Charles E. Rossi, Director

Division of Operational Events Assessment

Office of Nuclear Reactor Regulation

Technical contacts: Melvyn Leach, RIII

(708) 790-5559 Geoffrey Wright, RIII

(708) 790-5695 Paul O'Connor, NRR

(301) 504-1307 Attachment: List of Recently Issued NRC Information Notices

  • SEE PREVIOUS CONCURRENCE

OFC RIII ADR4-5:PD4-1 SC:DOEA:OEAB ADM:RPB C:DST:SRXB C:DOEA:OEAB

NAME GWright* PO'Connor* RDennig* JMain* RJones* AChaffee*

DATE 03/11/92 03/17/92 03/11/92 03/11/92 03/13/92 04/13/92 OFC C:DOEA:OGCB D:DOEA

NAME CBerlinger* CRoss tD

DATE 04/21/92 /9 OFFICIAL RECORD COPY DOCUMENT NAME: IN DENKIG

IN 92-XX

April xx, 1992 Further details of the event may be found in NRC Inspection Report

50-416/92-04 and Licensee Event Report 50-416/91-16.

Discussion

The underlying principle of reactivity management is to maintain the reactor

in the desired condition by properly anticipating, controlling, and responding

to the plant's changing parameters. Once a reactor has been placed in a

subcritical condition during a plant shutdown, it is of primary importance

that the reactor be maintained in that subcritical condition. Raising the

range of the IRMs in the event of recriticality can be inappropriate if the

licensed operators do not have management's oversight, training, and specific

procedures for this.

The experience at Grand Gulf and Monticello indicate that slow shutdowns in

situations with low decay heat present a unique challenge to reactivity

control and require the operator and management to give careful attention to

avoid recriticality. The events at Monticello and Big Rock Point also highlight

the importance of the operator giving continuous attention to plant parameters

during a shutdown.

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.

Charles E. Rossi, Director

Division of Operational Events Assessment

Office of Nuclear Reactor Regulation

Technical contacts: Melvyn Leach, RIII

(708) 790-5559 Geoffrey Wright, RIII

(708) 790-5695 Paul O'Connor, NRR

(301) 504-1307 Attachment: List of Recently Issued NRC Information Notices

  • SEE PREVIOUS CONCURRENCE

OFC RIII ADR4-5:PD4-1 SC:DOEA:OEAB ADM:RPB C:DST:SRXB C:DOEA:OEAB

NAME GWright* PO'Connor* RDennig* JMain* RJones* AChaffee*

DATE 03/11/92 03/17/92 03/11/92 03/11/92 03/13/92 04/13/92 OFC C:DO J

f D:DOEA

NAME CBerlinger CRosswa'y

DATE f/;11/ 92 / 92 OFFICIAL RECORD COPY DOCUMENT NAME: IN DENNIG

IN 92-XX

March xx, 1992 Further details of the event may be found in NRC Inspection Report

50-416/92-04 and Licensee Event Report 50-416/91-16.

Discussion

The underlying principle of reactivity management is to maintain the reactor

in the desired condition by properly anticipating, controlling, and responding

to the plant's changing parameters. Once a reactor has been placed in a

subcritical condition during a plant shutdown, it is of primary importance

that the reactor be maintained in that subcritical condition. In the event of

recriticality, promptly inserting control rods and terminating the cooldown are

more conservative actions than raising the range of the IRMs to prevent scram

while waiting on the changing temperature to reverse the direction of the

power. Raising the range of the IRMs in the event of recriticality can be

inappropriate if the licensed operators do not have management's oversight, training, and specific procedures.

The experience at Grand Gulf and Monticello indicate that slow shutdowns in

situations with low decay heat present a unique challenge to reactivity

control and require the operator and management to give careful attention to

avoid recriticality. The events at Monticello and Big Rock Point also highlight

the importance of the operator giving continuous attention to plant parameters

during a shutdown.

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.

Charles E. Rossi, Director

Division of Operational Events Assessment

Office of Nuclear Reactor Regulation

Technical contacts: Melvyn Leach, RIII

(708) 790-5559 Geoffrey Wright, RIII

(708) 790-5695 Paul O'Connor, NRR

(301) 504-1307 t'/ ' f' 4.f, IV

Attachment: List of Recently Issued NRC Information Notices

  • SEE PREVIOUS CONCURRENCEC

OFC RIII ADR4-5:PD4-1 SC:DOEA:OEAB ADM:RPB C:DST:SRXB C:D0EA:OEAB

NAME GWright* PO'Connor* RDennig* JMain* RJones* AChaffee

DATE 03/11/92 03/17/92 03/11/92 03/11/92 03/13/92 q1/t3/92 OFC C:DOEA:OGCB D:DOEA

NAME CBerlinger CRossi

DATE / /92 / /92 OFFICIAL RECORD COPY DOCUMENT NAME: IN DENNIG

IN 92-XX

March xx, 1992 Further details of the event may be found in NRC Inspection Report

50-416/92-04 and Licensee Event Report 50-416/91-16.

Discussion

The underlying principle of reactivity management is to maintain the reactor

in the desired condition by properly anticipating, controlling, and responding

to the plant's changing parameters. Once a reactor has been placed in a

subcritical condition during a plant shutdown, it is of primary importance

that the reactor be maintained in that subcritical condition. In the event of

recriticality, promptly inserting control rods and terminating the cooldown are

more conservative actions than raising the range of the IRMs to prevent scram

while waiting on the changing temperature to reverse the direction of the

power. Raising the range of the IRMs in the event of recriticality can be

inappropriate if the licensed operators do not have management's oversight, training, and specific procedures.

The experience at Grand Gulf and Monticello indicate that slow shutdowns in

situations with low decay heat present a unique challenge to reactivity

control and require the operator and management to give careful attention to

avoid recriticality. The events at Monticello and Big Rock Point also highlight

the importance of the operator giving continuous attention to plant parameters

during a shutdown.

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.

Charles E. Rossi, Director

Division of Operational Events Assessment

Office of Nuclear Reactor Regulation

Technical contacts: Melvyn Leach, RIII

(708) 790-5559 Geoffrey Wright, 'RIII

(708) 790-5695 Paul O'Connor, NRR

(301) 504-1307 Attachment: List of Recently Issued NRC Information Notices

  • SEE PREVIOUS CONCURRENCE

OFC RIII ADR4-5:PD4-1 SC:DOEA:OEAB ADM:RPB C:DST:SRXB C:DOEA:OEAB

NAME GWright* PO'Connor (OK RDennig* JMain* RJones* AChaffee

DATE 03/11/92 3 /17/92 Xis 192 03/11/92 03/13/92 / /92 OFC C:DOEA:OGCB D:DOEA

NAME CBerlinger CRossi

DATE / /92 / /92

IN 92-XX

March xx, 1992 Further details of the event may be found in NRC Inspection Report

50-416/92-04 and Licensee Event Report 50-416/91-16.

Discussion

The underlying principle of reactivity management is to maintain the reactor

in the desired condition by properly anticipating, controlling, and responding

to the plant's changing parameters. Once a reactor has been placed in a

subcritical condition during a plant shutdown, it is of primary importance

that the reactor be maintained in that subcritical condition. Since recriti- cality has not been avoided, promptly inserting control rods and terminating

the cooldown are more conservative actions than raising the range of the IRMs

to prevent scram while waiting on the changing temperature to reverse the

direction of the power. Raising the range of the IRMs in the event of recriti- cality can be inappropriate if the licensed operators do not have management's

oversight, training, and specific procedures.

The experience at Grand Gulf and Monticello indicate that slow shutdowns in

situations with low decay heat present a unique challenge to reactivity

control and require the operator and management to give careful attention to

avoid recriticality. The events at Monticello and Big Rock Point also highlight

the importance of the operator giving continuous attention to plant parameters

during a shutdown.

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.

Charles E. Rossi, Director

Division of Operational Events Assessment

Office of Nuclear Reactor Regulation

Technical contacts: Melvyn Leach, RIII

(708) 790-5559 Geoffrey Wright, RII

(708) 790-5695 Paul O'Connor, NRR

(301) 504-1307 Attachment: List of Recently Issued NRC Information Notices

  • SEE PREVIOUS CONCURRENCE

OFC :RIII :S Oq;:EfAB:ADM:RPB :C:D B :C:DOEA:OEAB :C:DOEA:OGCB :D:DOEA

____

_ _________----_ -- ____________ ---- _ -:---------------

NAME :GWright* :Rbennig :JMain* j Jones :AChaffee :CBerlinger :CRossi

DATE :03/11/92 :3 /11/92 :03/11/92  : /13/92  : / /92  : / /92  : / /92 OFFICIAL RECORD COPY

Document Name: IN DENNIG

Further details of the event may be found in NRC Inspection Report 50-416/92-04 and Licensee Event Report 50-416/91-16.

Discussion

The underlying principle of reactivity management is to maintain the reactor in

the desired condition by properly anticipating, controlling, and responding to

the plant's changing parameters. Once a reactor has been placed in a

subcritical condition, as part of a plant shutdown, it is of primary importance

that the reactor be maintained in that subcritical condition. Given that

recriticality has not been avoided, prompt insertion of control rods and

termination of the cooldown are more conservative actions than upranging IRMs

to prevent scram while waiting on temperature coefficients to turn power.

Upranging IRMs in the event of recriticality can be inappropriate if management

oversight, prior training, and specific procedures are absent.

The experience at Grand Gulf and Monticello indicate that slow shutdowns in

situations with low decay heat present a particular challenge to reactivity

control, and require heightened operator and management awareness to avoid

recriticality. In addition, the events at Monticello and Big Rock Point

highlight the importance of continuous operator attention to plant parameters

in the course of a shutdown.

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.

Charles E. Rossi, Director

Division of Operational Events Assessment

Office of Nuclear Reactor Regulation

Technical contacts: Melvyn Leach, RIII

(708) 790-5559 Geoffrey Wright, RIII

(708) 790-5695 Paul O'Connor, NRR

(301) 504-1307 Attachment: List of Recently Issued NRC Information Notices

OFC :RIII :SC:DOEA:OEAB:ADM:RPB :C:DST:SRXB :C:DOEA:OEAB :C:DOEA:OGCB :D:DOEA

NAME :GWright :RDennig :JMain_ w :RJones :AChaffee :CBerlinger :CRossi

DATE ://92 :1/92 :3/11 /92 :1/92  ://92 :1 /92  :/ /92 OFFICIAL RECORD COPY

Document Name: IN DENNIG/DUP

IN 92-XX

March xx, 1992 Further details of the event may be found in NRC Inspection Report

50-416/92-04 and Licensee Event Report 50-416/91-16.

Discussion

The underlying principle of reactivity management is to maintain the reactor

in the desired condition by properly anticipating, controlling, and responding

to the plant's changing parameters. Once a reactor has been placed in a

subcritical condition, as part of a plant shutdown, it is of primary importance

that the reactor be maintained in that subcritical condition. Given that

recriticality has not been avoided, prompt insertion of control rods and

termination of the cooldown are more conservative actions than upranging

IRMs to prevent scram while waiting on temperature coefficients to turn power.

Upranging IRMs in the event of recriticality can be inappropriate if management

oversight, prior training, and specific procedures are absent.

The experience at Grand Gulf and Monticello indicate that slow shutdowns in

situations with low decay heat present a particular challenge to reactivity

control, and require heightened operator and management awareness to avoid

recriticality. In addition, the events at Monticello and Big Rock Point

highlight the importance of continuous operator attention to plant parameters

in the course of a shutdown.

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.

Charles E. Rossi, Director

Division of Operational Events Assessment

Office of Nuclear Reactor Regulation

Technical contacts: Melvyn Leach, RIII

(708) 790-5559 Geoffrey Wright, RIII

(708) 790-5695 Paul O'Connor, NRR

(301) 504-1307 Attachment: List of Recently Issued NRC Information Notices

OFC :R111 bC:DOEA:OEAB:ADM:RPB :C:DST:SRXB :C:DOEA:OEAB :C:DOEA:OGCB :D:DOEA

NAME :GWrightV' :RDennig :JMain :RJones :AChaffee :CBerlinger :CRossi

DATE :3 /II/92  ://92  :/ /92  :/ /92  :/ /92  :/ /92  :/ /92 OFFICIAL RECORD COPY

Document Name: IN DENNIG