Information Notice 2019-03, Inadequate Implementation of Clearance Processes Results in Configuration Control Issues: Difference between revisions

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{{#Wiki_filter:ML19084A081 UNITED STATES
{{#Wiki_filter:UNITED STATES


NUCLEAR REGULATORY COMMISSION
NUCLEAR REGULATORY COMMISSION
Line 22: Line 22:
OFFICE OF NEW REACTORS
OFFICE OF NEW REACTORS


WASHINGTON, DC
WASHINGTON, DC 20555-0001 June 3, 2019 NRC INFORMATION NOTICE 2019-03:                INADEQUATE IMPLEMENTATION OF


20555-0001  June 3, 2019 NRC INFORMATION NOTICE 20
CLEARANCE PROCESSES RESULTS IN
1 9-03:  INADEQUATE IMPLEMENTATION OF CLEARANCE PROCESSES RESULT


===S IN CONFIGURATION CONTROL ISSUES===
CONFIGURATION CONTROL ISSUES


==ADDRESSEES==
==ADDRESSEES==
All holders of an operating license for a nonpower reactor (i.e., research reactor, test reactor, or critical assembly) under Title 10 of the Code of Federal Regulations
All holders of an operating license for a nonpower reactor (i.e., research reactor, test reactor, or


(10 CFR) Part 50, "Domestic Licensing of Production and Utilization Facilities," except those that have permanently ceased operations.
critical assembly) under Title 10 of the Code of Federal Regulations (10 CFR) Part 50,
Domestic Licensing of Production and Utilization Facilities, except those that have
 
permanently ceased operations.


All holders of an operating license or construction permit for a nuclear power reactor under
All holders of an operating license or construction permit for a nuclear power reactor under


10 CFR Part 50, except those that have permanently ceased operations and have certified that fuel has been permanently removed from the reactor vessel.
10 CFR Part 50, except those that have permanently ceased operations and have certified that


All holders of and applicants for a combined license
fuel has been permanently removed from the reactor vessel.


under 10 CFR Part 52, "Licenses, Certifications, and Approvals for Nuclear Power Plants."
All holders of and applicants for a combined license under 10 CFR Part 52, Licenses, Certifications, and Approvals for Nuclear Power Plants.


==PURPOSE==
==PURPOSE==
The U.S. Nuclear Regulatory Commission (NRC) is issuing this information notice (IN) to inform addressees of several recent events in which operators failed to ensure the proper implementation of plant processes governing clearance activities
The U.S. Nuclear Regulatory Commission (NRC) is issuing this information notice (IN) to inform


that result ed in configuration control issues that affect ed the operability of safety
addressees of several recent events in which operators failed to ensure the proper


-related systems.  The NRC expect s that recipients will review the information for applicability to
implementation of plant processes governing clearance activities that resulted in configuration


their facilities and consider actions, as appropriate, to avoid similar issues. However, the suggestions in this IN are not NRC requirements; therefore, no specific action or written response is required.
control issues that affected the operability of safety-related systems. The NRC expects that


==DESCRIPTION OF CIRCUMSTANCES==
recipients will review the information for applicability to their facilities and consider actions, as


===Cooper Nuclear Station  On September 29, 2016===
appropriate, to avoid similar issues. However, the suggestions in this IN are not NRC
, during planned maintenance on the Division


1 residual heat removal (RHR) system during a scheduled refueling outage at Cooper Nuclear
requirements; therefore, no specific action or written response is required.


Station , the RHR minimum flow isolation valves were danger-tagged in the closed position
==DESCRIPTION OF CIRCUMSTANCES==


, as required by a clearance order
===Cooper Nuclear Station===
On September 29, 2016, during planned maintenance on the Division 1 residual heat removal


.  On October 7, 2016, when the
(RHR) system during a scheduled refueling outage at Cooper Nuclear Station, the RHR


clearance order
minimum flow isolation valves were danger-tagged in the closed position, as required by a


was lifted , licensee personnel failed to reposition the RHR minimum flow isolation valves for RHR pumps A and C to the open position before reinstalling the valve sealing devices.  The clearance order directed that the valves be repositioned to open, then sealed in the open position
clearance order.


as part of restoration
On October 7, 2016, when the clearance order was lifted, licensee personnel failed to reposition


to reduce the chances that the valves could be inadvertently shut.  The clearance order also required a
the RHR minimum flow isolation valves for RHR pumps A and C to the open position before


IN 2019-0 3 second, independent verification of the valve restoration. Both the individual responsible for repositioning and sealing the valves
reinstalling the valve sealing devices. The clearance order directed that the valves be


, and the individual responsible for verifying the valve position , confirmed through their signatures that the rising
repositioned to open, then sealed in the open position as part of restoration to reduce the


-stem manually operated valves were sealed in the open position. A quarterly sealed valve audit conducted from November
chances that the valves could be inadvertently shut. The clearance order also required a


23-29, 2016 , verified that the seals on the valves were correctly installed.  However, the procedure did not require verification of the position of the valves
ML19084A081 second, independent verification of the valve restoration. Both the individual responsible for


; i t only required verification
repositioning and sealing the valves, and the individual responsible for verifying the valve


that the seals were intact
position, confirmed through their signatures that the rising-stem manually operated valves were


.  The incorrect position was not noted at the time.  On February 5, 2017, during the next quarterly sealed valve audit, the operator performing the audit noted that the position of the rising stems indicated that the valves appeared closed and notified the control room. Personnel were directed to reposition
sealed in the open position.


the valves
A quarterly sealed valve audit conducted from November 23-29, 2016, verified that the seals on


and seal them open, restoring operability of the Division
the valves were correctly installed. However, the procedure did not require verification of the


1 RHR system.
position of the valves; it only required verification that the seals were intact. The incorrect


The licensee determined that the affected pumps had been operated 15 times while the minimum flow line was isolated and that the longest time any pump was continuously operated in this condition was 2 minutes and 18 seconds.
position was not noted at the time. On February 5, 2017, during the next quarterly sealed valve


After demonstrating satisfactory performance of the affected pumps using the
audit, the operator performing the audit noted that the position of the rising stems indicated that


2-year comprehensive surveillance test procedure and performing a detailed analysis of the
the valves appeared closed and notified the control room. Personnel were directed to reposition


2-year comprehensive surveillance data by comparing test results from October
the valves and seal them open, restoring operability of the Division 1 RHR system.


2007 through February
The licensee determined that the affected pumps had been operated 15 times while the


6, 2017, the licensee's evaluation of operability concluded that
minimum flow line was isolated and that the longest time any pump was continuously operated


the Division
in this condition was 2 minutes and 18 seconds. After demonstrating satisfactory performance


1 RHR pumps
of the affected pumps using the 2-year comprehensive surveillance test procedure and


had not degraded
performing a detailed analysis of the 2-year comprehensive surveillance data by comparing test


.  The NRC chartered a
results from October 2007 through February 6, 2017, the licensees evaluation of operability


special inspection in response to this event
concluded that the Division 1 RHR pumps had not degraded.


and identified a noncited violation of
The NRC chartered a special inspection in response to this event and identified a noncited


technical specification requirements for the operability of the emergency core cooling system.  Cooper Licensee Event Report 05000298/2017
violation of technical specification requirements for the operability of the emergency core cooling
-001-01 , "Residual Heat Removal Minimum Flow Valves


out of Position Results in Loss of Safety Function and Condition Prohibited by Technical Specifications," Revision 1, dated December
system. Cooper Licensee Event Report 05000298/2017-001-01, Residual Heat Removal


15, 2017 (Agencywide Documents Access and Management System (ADAMS)
Minimum Flow Valves out of Position Results in Loss of Safety Function and Condition
Accession No.


ML17354A150), and NRC Special Inspection Report 05000298/2017009, dated June
Prohibited by Technical Specifications, Revision 1, dated December 15, 2017 (Agencywide


27, 2017 (ADAMS Accession No. ML17179A282
Documents Access and Management System (ADAMS) Accession No. ML17354A150), and
), provide further details on this event


.  Clinton Power Station
NRC Special Inspection Report 05000298/2017009, dated June 27, 2017 (ADAMS Accession


During a scheduled refueling outage at Clinton Power Station, the licensee hung tags under several clearance orders, including on the Division
No. ML17179A282), provide further details on this event.


2 emergency diesel generator (EDG) and associated support systems, for planned
===Clinton Power Station===
During a scheduled refueling outage at Clinton Power Station, the licensee hung tags under


work on the 1B1 electrical
several clearance orders, including on the Division 2 emergency diesel generator (EDG) and


bus. On May
associated support systems, for planned work on the 1B1 electrical bus. On May 9, 2018, one


9, 2018, one of the clearance orders, which included the Division
of the clearance orders, which included the Division 2 EDG air receiver isolation valves, was


2 EDG air receiver isolation valves, was completed , with instructions to
completed, with instructions to remove tags and restore the systems involved to standby status.


remove tags and
However, a note in the control room log stated that system restoration was not completed and


restore the systems involved to standby
needed to be performed after other ongoing work associated with the Division 2 shutdown


status. However, a note in the control room log stated that system restoration was not completed and needed to be performed after other ongoing work associated with the Division
service water system was finished. The clearance order was closed out with only the control


2 shutdown service water system
room log entry tracking the abnormal (closed) position of the Division 2 EDG air receiver


was finished. The clearance order
isolation valves.


was closed out with only the control room log entry tracking the abnormal (closed) position of
The following day, a control room operator directed a portion of the clearance order for the EDG


the Division
system restoration procedure to be completed to restore the Division 2 EDG lubrication system.


2 EDG air receiver isolation valves.
The operator who directed the restoration turned over the shift before completion of the activity.


The following day, a control room operator directed a portion of the clearance order for the EDG system restoration procedure to be completed to restore the Division
When the partially completed restoration procedure was returned to the control room, the new


2 EDG lubrication system.  The operato
control room operator incorrectly believed that all restoration activities for the Division 2 EDG


r who direct ed the restoration turned over the shift before completion of the activity. When the partially completed restoration procedure was returned to the control room, the new control room operator incorrectly believed that all restoration activities
had been completed and declared the EDG operable early on May 11, 2018. Three days later at 12:30 a.m. on May 14, 2018, the Division 1 EDG was declared inoperable


for the Division
for scheduled maintenance on the 1A1 electrical bus. At this point, with the Division 2 EDG air


2 EDG had been completed and declared the EDG operable early on May
receiver isolation valves still in the closed position, both EDGs were inoperable. Had a loss of


11, 2018.
offsite power event occurred, an immediate station blackout event would have taken place. The


IN 2019-0 3 Three days later
impact would have been mitigated by the availability of diverse and flexible coping strategies


at 12:30 a.m. on May
(FLEX) equipment, the smaller Division 3 EDG that could have been cross-tied to selected


14, 2018, the Division
Division 2 loads, and two diesel-driven fire pumps that could have worked in conjunction with


1 EDG was declared inoperable for scheduled maintenance on the 1A1 electrical bus. At this point, with the Division
safety relief valves to provide feed-and-bleed cooling to the reactor core if necessary.


2 EDG air receiver isolation valves still in the closed position, both EDGs were inoperable.  Had a loss of offsite power event occurred, an immediate station blackout event
The licensee discovered the out-of-position air receiver isolation valves on the Division 2 EDG


would have taken place
during shift rounds on May 17, 2018. It restored the valves to the open position and declared


. The impact would have been mitigated by the availability of diverse and flexible coping strategies
the EDG operable at 9:04 p.m. that evening.


(FLEX) equipment, the smaller Division
The NRC chartered a special inspection in response to this event and identified a violation of


3 EDG that could have been cross
Criterion V, Instruction, Procedures, and Drawings, of Appendix B, Quality Assurance Criteria


-tied to selected Division 2 loads, and two diesel
for Nuclear Power Plants and Fuel Reprocessing Plants, to 10 CFR Part 50 and the technical


-driven fire pumps that could have worked in conjunction with safety relief valves to provide feed
specification requirements for EDG operability. Clinton Licensee Event Report


-and-bleed cooling to the reactor core if necessary.
05000461/2018-002, Division 2 Diesel Generator lnoperability due to Air Receiver Remaining


The licensee discovered the out-of-position air receiver isolation valves on the Division
Isolated Following Clearance Removal Resulting in Unplanned Shutdown Risk Change, dated


2 EDG during shift rounds on May
July 16, 2018 (ADAMS Accession No. ML18199A106); NRC Special Inspection Report


17, 2018. It restored the valves to the open position and declared the EDG operable at 9:04 p.m. that evening.
05000461/2018050, dated August 23, 2018 (ADAMS Accession No. ML18235A170); NRC


The NRC chartered a
Inspection Report 05000461/2018051, dated November 6, 2018 (ADAMS Accession


special inspection in response to this event
No. ML18311A151); and NRC Inspection Report 05000461/2018092, dated April 1, 2019 (ADAMS Accession No. ML19092A212), provide further details on this event.


and identified a violation of Criterion V, "Instruction, Procedures, and Drawings
===Watts Bar Nuclear Plant, Unit 1===
On July 21, 2018, the licensee for Watts Bar Nuclear Plant performed work to repair a leak on a


," of Appendix
7.6-centimeter (3-inch) pipe in the high-pressure fire protection (HPFP) system. Before


B, "Quality Assurance Criteria for Nuclear Power Plants and Fuel Reprocessing Plants," to 10
beginning the work, the licensee generated a clearance order to isolate and tag out the affected
CFR Part 50 and the technical specification requirements for EDG operability.  Clinton Licensee Event Report 05000461/2018
-002, "Division 2 Diesel Generator lnoperability


due to Air Receiver Remaining Isolated Following Clearance Removal Resulting in Unplanned Shutdown Risk Change," dated July 16, 2018 (ADAMS Accession No
portion of the system. The Remarks section of the clearance order specified a drain valve and


. ML18199A106)
two vent valves that were to be used to drain that portion of the system; however, the valves
; NRC Special Inspection Report 05000461/2018050, dated August


23, 2018 (ADAMS Accession No.
were not written into the tagging portion of the clearance order. Therefore, the order did not


ML18235A170
assign any information or danger tags to these valves. Licensee personnel attempting to drain
); NRC Inspection Report


05000461/2018051, dated November
the piping found that the valves identified on the clearance order were insufficient for the task.


6, 2018 (ADAMS Accession No. ML18311A151); and NRC Inspection Report 05000461/2018092, dated April 1, 2019 (ADAMS Accession No. ML19092A212), provide further details on this event
Additional drain locations were identified through an e-mail from the fire marshal, and they


. Watts Bar Nuclear Plant, Unit 1  On July 21, 2018 , the licensee for Watts Bar Nuclear Plant performed work to repair a leak on a 7.6-centimeter (3-inch) pipe in the
proved adequate for draining the system. However, the clearance order was not modified to


high-pressure fire protection (HPFP) system. Before beginning the work, the licensee generated a clearance order to isolate and tag out the affected portion of the system.  The "Remarks" section
identify these additional drains.


of the clearance order specified a drain valve and two vent valves that were to be used to drain that portion of the system; however, the valves were not written into the tagging portion of the clearance order.  Therefore, the order did not assign any information or danger tags to these valves.
After completing the pipe repair, the licensee restored the system based on the tags identified in


===Licensee personnel attempting to drain the piping===
the clearance order. The licensee personnel responsible for restoration did not recognize that
found that the valves identified on the clearance order were


insufficient
either the drain or vents identified in the Remarks section of the clearance order or the drains


for the task.  Additional drain locations were identified through an e-mail from the fire marshal, and they proved adequate for draining the system
identified in the fire marshals e-mail were still open. As a result, the clearance order was


. However, the clearance order was not modified to identify these additional drains.
released with these components still open. As the HPFP system was returned to operation, water discharged through the open vent and drain paths and flooded portions of the Unit 1 auxiliary building and the Unit 1 auxiliary equipment building.


After completing the pipe repair, the licensee restored the system based on the tags identified in the clearance order.  The licensee personnel responsible for restoration did not recognize that either the drain or vents identified in the "Remarks" section of the clearance order or the drains identified in the
The flooding caused the annunciation of alarms in the control room from (1) high sump levels,
(2) erratic indications to the source range and intermediate-range nuclear instruments caused


fire marshal's e
by water intrusion to electrical equipment associated with the instruments, and (3) grounds on


-mail were still open. As a result, the clearance order was released with these components
the Unit 1 vital battery boards. The licensee isolated the affected portions of the HPFP header, performed walkdowns to identify potentially affected equipment, and evaluated the continued


still open. As the HPFP system was returned to operation, water discharged through the open vent and drain paths
operability of the equipment.


and flood ed portions of the Unit 1 auxiliary building and the Unit 1 auxiliary equipment building.
The event resulted in a noncited violation of technical specification requirements for


The flooding caused the annunciation of alarms in the control room from (1) high sump levels, (2) erratic indications to the source range and intermediate
implementing procedures. NRC Integrated Inspection Report 05000390/2018003 and


-range nuclear instruments caused by water intrusion to electrical equipment associated with the instruments, and (3) grounds on the Unit 1 vital batter
05000391/2018003, dated November 1, 2018 (ADAMS Accession No. ML18308A007), provides


y boards. The licensee isolated the affected portions of the HPFP header , 
further details.
IN 2019-0 3 performed walkdowns to identify potentially affected equipment


, and evaluate
==DISCUSSION==
 
Operability of systems required by plant technical specifications depends on operator
d the continued operability
 
of the equipment
 
. The event resulted in a noncited violation of
 
technical specification requirements for implementing procedures.  NRC Integrated Inspection Report
 
05000390/2018003 and 05000391/201
8 00 3, dated November 1, 2018 (ADAMS Accession No.
 
ML18308A007), provides further details.


==DISCUSSION==
awareness of the current configuration of system components to ensure compliance with the
Operability of systems required by plant


technical specifications depends
plant-specific licensing basis. Plant procedures that govern clearance activities allow for the


on operator awareness of the current configuration of
systematic isolation, tagging, and subsequent restoration of components and systems for


system components to ensure compliance with
maintenance and testing activities. Performing these activities in a deliberate manner


the plant-specific licensing basis.  Plant procedures that govern clearance activities allow for the systematic isolation, tagging, and subsequent restoration of components and systems for maintenance and testing activities.  Performing these activities in
establishes an instrumental administrative barrier that helps to ensure the safety of plant


a deliberate manner establishes an
personnel by providing proper isolation of high-energy systems and ensuring the operability of


instrumental administrative barrier that helps to ensure the safety
equipment relied on for safe plant operation.


of plant personnel by providing proper isolation of high
The events described above illustrate how the clearance process can break down. Valve


-energy systems and ensuring the operability of equipment relied on for safe plant operation.
manipulations outside the documented scope of work, inadequate communications during the


The events described above illustrate how the clearance process can break down.  Valve manipulations outside
turnover of ongoing work across multiple shifts, actions taken based on assumptions made


the documented scope of work, inadequate
without adequate verification, and informal methods of tracking abnormal component


communications
configurations on systems with the ability to impact safety were contributing factors to these


during the turnover of ongoing work
events. Rigorous adherence to process requirements for tracking components in an abnormal


across multiple shifts , actions taken based
configuration, even when current plant conditions allow such a configuration, helps maintain


on assumptions made without adequate verification, and informal methods of tracking abnormal component configurations on systems with the ability to impact safety were contributing factors to these events.  Rigorous adherence to process requirements for tracking components in an abnormal configuration, even when current plant conditions
awareness for potential impacts to operability and facilitates communication for work that


allow such a configuration, helps maintain awareness for potential impacts to operability and facilitates communication for work that continues across multiple shifts.
continues across multiple shifts.


==CONTACT==
==CONTACT==
This IN requires no specific action or written response. Please direct any questions about this matter to the technical contact
This IN requires no specific action or written response. Please direct any questions about this


s listed below or to the appropriate
matter to the technical contacts listed below or to the appropriate NRC Office of Nuclear


NRC Office of Nuclear Reactor Regulation (NRR)
Reactor Regulation (NRR) project manager.
project manager.


/RA/     /RA/ Robert M. Taylor   Christopher G. Miller, Director
/RA/                                           /RA/
Robert M. Taylor                               Christopher G. Miller, Director


Division of Licensing, Siting, and
Division of Licensing, Siting, and             Division of Inspection and Regional Support


Division of Inspection and Regional Support
Environmental Analysis                        Office of Nuclear Reactor Regulation


Environmental Analysis
===Office of New Reactors===
 
Office of Nuclear Reactor Regulation
 
Office of New Reactors


===Technical Contact:===
===Technical Contact:===
Rebecca Sigmon , NRR    301-415-0895  Rebecca.Sigmon@nrc.gov
IN 2019-0 3 Note:  NRC generic communications may be found on the NRC public Web site, http://www.nrc.gov, under NRC Library
.  ADAMS Accession Number: ML19084A081    *via email
OFFICE TECH EDITOR
* NRR/DIRS/IOEB
* NRR/DIRS/IOEB


* NRR/DIRS/IOEB/BC
===Rebecca Sigmon, NRR===
                        301-415-0895 Rebecca.Sigmon@nrc.gov Note: NRC generic communications may be found on the NRC public Web site, http://www.nrc.gov, under NRC Library.


* NRR/DIRS/ IRGB/LA NAME JDoughtery
ADAMS Accession Number: ML19084A081          *via email


RSigmon AIssa RElliott BCurran
OFFICE  TECH EDITOR*      NRR/DIRS/IOEB*      NRR/DIRS/IOEB* NRR/DIRS/IOEB/BC*  NRR/DIRS/
                                                                                IRGB/LA


* w/edits DATE 3/27/2019 4/24/2019 4/26/2019 5/3/2019 04/03/2019 OFFICE NRR/DIRS/IRGB/PM
NAME    JDoughtery        RSigmon            AIssa          RElliott          BCurran


NRR/DIRS/IRGB/BC
* w/edits


* NRO/DLSE/D
DATE    3/27/2019        4/24/2019          4/26/2019      5/3/2019          04/03/2019 OFFICE  NRR/DIRS/IRGB/PM  NRR/DIRS/IRGB/BC*   NRO/DLSE/D*    NRR/DIRS/D


* NRR/DIRS/D
NAME    BBenney          TInverso            RTaylor        CMiller


NAME BBenney TInverso RTaylor CMiller  DATE 5/6/2019 5/6/2019 5/24/2019 06/03/2019 OFFICIAL RECORD COPY}}
DATE     5/6/2019         5/6/2019           5/24/2019     06/03/2019 OFFICIAL RECORD COPY}}


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

Revision as of 22:36, 19 October 2019

Inadequate Implementation of Clearance Processes Results in Configuration Control Issues
ML19084A081
Person / Time
Issue date: 06/03/2019
From: Chris Miller, Rebecca Sigmon, Renee Taylor
NRC/NRR/DIRS/IOEB
To:
Benney B
References
IN-19-003
Download: ML19084A081 (5)
v • d • e


UNITED STATES

NUCLEAR REGULATORY COMMISSION

OFFICE OF NUCLEAR REACTOR REGULATION

OFFICE OF NEW REACTORS

WASHINGTON, DC 20555-0001 June 3, 2019 NRC INFORMATION NOTICE 2019-03: INADEQUATE IMPLEMENTATION OF

CLEARANCE PROCESSES RESULTS IN

CONFIGURATION CONTROL ISSUES

ADDRESSEES

All holders of an operating license for a nonpower reactor (i.e., research reactor, test reactor, or

critical assembly) under Title 10 of the Code of Federal Regulations (10 CFR) Part 50,

Domestic Licensing of Production and Utilization Facilities, except those that have

permanently ceased operations.

All holders of an operating license or construction permit for a nuclear power reactor under

10 CFR Part 50, except those that have permanently ceased operations and have certified that

fuel has been permanently removed from the reactor vessel.

All holders of and applicants for a combined license under 10 CFR Part 52, Licenses, Certifications, and Approvals for Nuclear Power Plants.

PURPOSE

The U.S. Nuclear Regulatory Commission (NRC) is issuing this information notice (IN) to inform

addressees of several recent events in which operators failed to ensure the proper

implementation of plant processes governing clearance activities that resulted in configuration

control issues that affected the operability of safety-related systems. The NRC expects that

recipients will review the information for applicability to their facilities and consider actions, as

appropriate, to avoid similar issues. However, the suggestions in this IN are not NRC

requirements; therefore, no specific action or written response is required.

DESCRIPTION OF CIRCUMSTANCES

Cooper Nuclear Station

On September 29, 2016, during planned maintenance on the Division 1 residual heat removal

(RHR) system during a scheduled refueling outage at Cooper Nuclear Station, the RHR

minimum flow isolation valves were danger-tagged in the closed position, as required by a

clearance order.

On October 7, 2016, when the clearance order was lifted, licensee personnel failed to reposition

the RHR minimum flow isolation valves for RHR pumps A and C to the open position before

reinstalling the valve sealing devices. The clearance order directed that the valves be

repositioned to open, then sealed in the open position as part of restoration to reduce the

chances that the valves could be inadvertently shut. The clearance order also required a

ML19084A081 second, independent verification of the valve restoration. Both the individual responsible for

repositioning and sealing the valves, and the individual responsible for verifying the valve

position, confirmed through their signatures that the rising-stem manually operated valves were

sealed in the open position.

A quarterly sealed valve audit conducted from November 23-29, 2016, verified that the seals on

the valves were correctly installed. However, the procedure did not require verification of the

position of the valves; it only required verification that the seals were intact. The incorrect

position was not noted at the time. On February 5, 2017, during the next quarterly sealed valve

audit, the operator performing the audit noted that the position of the rising stems indicated that

the valves appeared closed and notified the control room. Personnel were directed to reposition

the valves and seal them open, restoring operability of the Division 1 RHR system.

The licensee determined that the affected pumps had been operated 15 times while the

minimum flow line was isolated and that the longest time any pump was continuously operated

in this condition was 2 minutes and 18 seconds. After demonstrating satisfactory performance

of the affected pumps using the 2-year comprehensive surveillance test procedure and

performing a detailed analysis of the 2-year comprehensive surveillance data by comparing test

results from October 2007 through February 6, 2017, the licensees evaluation of operability

concluded that the Division 1 RHR pumps had not degraded.

The NRC chartered a special inspection in response to this event and identified a noncited

violation of technical specification requirements for the operability of the emergency core cooling

system. Cooper Licensee Event Report 05000298/2017-001-01, Residual Heat Removal

Minimum Flow Valves out of Position Results in Loss of Safety Function and Condition

Prohibited by Technical Specifications, Revision 1, dated December 15, 2017 (Agencywide

Documents Access and Management System (ADAMS) Accession No. ML17354A150), and

NRC Special Inspection Report 05000298/2017009, dated June 27, 2017 (ADAMS Accession

No. ML17179A282), provide further details on this event.

Clinton Power Station

During a scheduled refueling outage at Clinton Power Station, the licensee hung tags under

several clearance orders, including on the Division 2 emergency diesel generator (EDG) and

associated support systems, for planned work on the 1B1 electrical bus. On May 9, 2018, one

of the clearance orders, which included the Division 2 EDG air receiver isolation valves, was

completed, with instructions to remove tags and restore the systems involved to standby status.

However, a note in the control room log stated that system restoration was not completed and

needed to be performed after other ongoing work associated with the Division 2 shutdown

service water system was finished. The clearance order was closed out with only the control

room log entry tracking the abnormal (closed) position of the Division 2 EDG air receiver

isolation valves.

The following day, a control room operator directed a portion of the clearance order for the EDG

system restoration procedure to be completed to restore the Division 2 EDG lubrication system.

The operator who directed the restoration turned over the shift before completion of the activity.

When the partially completed restoration procedure was returned to the control room, the new

control room operator incorrectly believed that all restoration activities for the Division 2 EDG

had been completed and declared the EDG operable early on May 11, 2018. Three days later at 12:30 a.m. on May 14, 2018, the Division 1 EDG was declared inoperable

for scheduled maintenance on the 1A1 electrical bus. At this point, with the Division 2 EDG air

receiver isolation valves still in the closed position, both EDGs were inoperable. Had a loss of

offsite power event occurred, an immediate station blackout event would have taken place. The

impact would have been mitigated by the availability of diverse and flexible coping strategies

(FLEX) equipment, the smaller Division 3 EDG that could have been cross-tied to selected

Division 2 loads, and two diesel-driven fire pumps that could have worked in conjunction with

safety relief valves to provide feed-and-bleed cooling to the reactor core if necessary.

The licensee discovered the out-of-position air receiver isolation valves on the Division 2 EDG

during shift rounds on May 17, 2018. It restored the valves to the open position and declared

the EDG operable at 9:04 p.m. that evening.

The NRC chartered a special inspection in response to this event and identified a violation of

Criterion V, Instruction, Procedures, and Drawings, of Appendix B, Quality Assurance Criteria

for Nuclear Power Plants and Fuel Reprocessing Plants, to 10 CFR Part 50 and the technical

specification requirements for EDG operability. Clinton Licensee Event Report

05000461/2018-002, Division 2 Diesel Generator lnoperability due to Air Receiver Remaining

Isolated Following Clearance Removal Resulting in Unplanned Shutdown Risk Change, dated

July 16, 2018 (ADAMS Accession No. ML18199A106); NRC Special Inspection Report 05000461/2018050, dated August 23, 2018 (ADAMS Accession No. ML18235A170); NRC

Inspection Report 05000461/2018051, dated November 6, 2018 (ADAMS Accession

No. ML18311A151); and NRC Inspection Report 05000461/2018092, dated April 1, 2019 (ADAMS Accession No. ML19092A212), provide further details on this event.

Watts Bar Nuclear Plant, Unit 1

On July 21, 2018, the licensee for Watts Bar Nuclear Plant performed work to repair a leak on a

7.6-centimeter (3-inch) pipe in the high-pressure fire protection (HPFP) system. Before

beginning the work, the licensee generated a clearance order to isolate and tag out the affected

portion of the system. The Remarks section of the clearance order specified a drain valve and

two vent valves that were to be used to drain that portion of the system; however, the valves

were not written into the tagging portion of the clearance order. Therefore, the order did not

assign any information or danger tags to these valves. Licensee personnel attempting to drain

the piping found that the valves identified on the clearance order were insufficient for the task.

Additional drain locations were identified through an e-mail from the fire marshal, and they

proved adequate for draining the system. However, the clearance order was not modified to

identify these additional drains.

After completing the pipe repair, the licensee restored the system based on the tags identified in

the clearance order. The licensee personnel responsible for restoration did not recognize that

either the drain or vents identified in the Remarks section of the clearance order or the drains

identified in the fire marshals e-mail were still open. As a result, the clearance order was

released with these components still open. As the HPFP system was returned to operation, water discharged through the open vent and drain paths and flooded portions of the Unit 1 auxiliary building and the Unit 1 auxiliary equipment building.

The flooding caused the annunciation of alarms in the control room from (1) high sump levels,

(2) erratic indications to the source range and intermediate-range nuclear instruments caused

by water intrusion to electrical equipment associated with the instruments, and (3) grounds on

the Unit 1 vital battery boards. The licensee isolated the affected portions of the HPFP header, performed walkdowns to identify potentially affected equipment, and evaluated the continued

operability of the equipment.

The event resulted in a noncited violation of technical specification requirements for

implementing procedures. NRC Integrated Inspection Report 05000390/2018003 and

05000391/2018003, dated November 1, 2018 (ADAMS Accession No. ML18308A007), provides

further details.

DISCUSSION

Operability of systems required by plant technical specifications depends on operator

awareness of the current configuration of system components to ensure compliance with the

plant-specific licensing basis. Plant procedures that govern clearance activities allow for the

systematic isolation, tagging, and subsequent restoration of components and systems for

maintenance and testing activities. Performing these activities in a deliberate manner

establishes an instrumental administrative barrier that helps to ensure the safety of plant

personnel by providing proper isolation of high-energy systems and ensuring the operability of

equipment relied on for safe plant operation.

The events described above illustrate how the clearance process can break down. Valve

manipulations outside the documented scope of work, inadequate communications during the

turnover of ongoing work across multiple shifts, actions taken based on assumptions made

without adequate verification, and informal methods of tracking abnormal component

configurations on systems with the ability to impact safety were contributing factors to these

events. Rigorous adherence to process requirements for tracking components in an abnormal

configuration, even when current plant conditions allow such a configuration, helps maintain

awareness for potential impacts to operability and facilitates communication for work that

continues across multiple shifts.

CONTACT

This IN requires no specific action or written response. Please direct any questions about this

matter to the technical contacts listed below or to the appropriate NRC Office of Nuclear

Reactor Regulation (NRR) project manager.

/RA/ /RA/

Robert M. Taylor Christopher G. Miller, Director

Division of Licensing, Siting, and Division of Inspection and Regional Support

Environmental Analysis Office of Nuclear Reactor Regulation

Office of New Reactors

Technical Contact:

Rebecca Sigmon, NRR

301-415-0895 Rebecca.Sigmon@nrc.gov Note: NRC generic communications may be found on the NRC public Web site, http://www.nrc.gov, under NRC Library.

ADAMS Accession Number: ML19084A081 *via email

OFFICE TECH EDITOR* NRR/DIRS/IOEB* NRR/DIRS/IOEB* NRR/DIRS/IOEB/BC* NRR/DIRS/

IRGB/LA

NAME JDoughtery RSigmon AIssa RElliott BCurran

  • w/edits

DATE 3/27/2019 4/24/2019 4/26/2019 5/3/2019 04/03/2019 OFFICE NRR/DIRS/IRGB/PM NRR/DIRS/IRGB/BC* NRO/DLSE/D* NRR/DIRS/D

NAME BBenney TInverso RTaylor CMiller

DATE 5/6/2019 5/6/2019 5/24/2019 06/03/2019 OFFICIAL RECORD COPY


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