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

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


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


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


CLEARANCE PROCESSES RESULTS IN
CLEARANCE PROCESSES RESULTS IN
Line 31: Line 36:
All holders of an operating license for a nonpower reactor (i.e., research reactor, test reactor, or
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,
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
Domestic Licensing of Production and Utilization Facilities, except those that have


Line 51: Line 56:
implementation of plant processes governing clearance activities that resulted in configuration
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
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
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
appropriate, to avoid similar issues. However, the suggestions in this IN are not NRC


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


==DESCRIPTION OF CIRCUMSTANCES==
==DESCRIPTION OF CIRCUMSTANCES==
Cooper Nuclear Station


===Cooper Nuclear Station===
On September 29, 2016, during planned maintenance on the Division 1 residual heat removal
On September 29, 2016, during planned maintenance on the Division 1 residual heat removal


Line 74: Line 79:
the RHR minimum flow isolation valves for RHR pumps A and C to the open position before
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
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
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
chances that the valves could be inadvertently shut. The clearance order also required a second, independent verification of the valve restoration. Both the individual responsible for
 
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
repositioning and sealing the valves, and the individual responsible for verifying the valve
Line 90: Line 93:
A quarterly sealed valve audit conducted from November 23-29, 2016, verified that the seals on
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
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 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
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
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 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 valves and seal them open, restoring operability of the Division 1 RHR system.
Line 106: Line 109:
minimum flow line was isolated and that the longest time any pump was continuously operated
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
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
of the affected pumps using the 2-year comprehensive surveillance test procedure and
Line 120: Line 123:
violation of technical specification requirements for the operability of the emergency core cooling
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
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
Minimum Flow Valves out of Position Results in Loss of Safety Function and Condition
Line 132: Line 135:
No. ML17179A282), provide further details on this event.
No. ML17179A282), provide further details on this event.


===Clinton Power Station===
Clinton Power Station
 
During a scheduled refueling outage at Clinton Power Station, the licensee hung tags under
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
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
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
of the clearance orders, which included the Division 2 EDG air receiver isolation valves, was
Line 147: Line 151:
needed to be performed after other ongoing work associated with the Division 2 shutdown
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
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
room log entry tracking the abnormal (closed) position of the Division 2 EDG air receiver
Line 165: Line 169:
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
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
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
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
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
impact would have been mitigated by the availability of diverse and flexible coping strategies
Line 181: Line 185:
The licensee discovered the out-of-position air receiver isolation valves on the Division 2 EDG
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
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 EDG operable at 9:04 p.m. that evening.
Line 191: Line 195:
for Nuclear Power Plants and Fuel Reprocessing Plants, to 10 CFR Part 50 and the technical
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
specification requirements for EDG operability. Clinton Licensee Event Report


05000461/2018-002, Division 2 Diesel Generator lnoperability due to Air Receiver Remaining
05000461/2018-002, Division 2 Diesel Generator lnoperability due to Air Receiver Remaining
Line 205: Line 209:
No. ML18311A151); and NRC Inspection Report 05000461/2018092, dated April 1, 2019 (ADAMS Accession No. ML19092A212), provide further details on this event.
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===
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
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
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
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
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
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
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
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.
the piping found that the valves identified on the clearance order were insufficient for the task.
Line 224: Line 229:
Additional drain locations were identified through an e-mail from the fire marshal, and they
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
proved adequate for draining the system. However, the clearance order was not modified to


identify these additional drains.
identify these additional drains.
Line 230: Line 235:
After completing the pipe repair, the licensee restored the system based on the tags identified in
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
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
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
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.
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,
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
(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
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
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.
operability of the equipment.
Line 249: Line 254:
The event resulted in a noncited violation of technical specification requirements for
The event resulted in a noncited violation of technical specification requirements for


implementing procedures. NRC Integrated Inspection Report 05000390/2018003 and
implementing procedures. NRC Integrated Inspection Report 05000390/2018003 and


05000391/2018003, dated November 1, 2018 (ADAMS Accession No. ML18308A007), provides
05000391/2018003, dated November 1, 2018 (ADAMS Accession No. ML18308A007), provides
Line 260: Line 265:
awareness of the current configuration of system components to ensure compliance with the
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
plant-specific licensing basis. Plant procedures that govern clearance activities allow for the


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


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


establishes an instrumental administrative barrier that helps to ensure the safety of plant
establishes an instrumental administrative barrier that helps to ensure the safety of plant
Line 272: Line 277:
equipment relied on for safe plant operation.
equipment relied on for safe plant operation.


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


manipulations outside the documented scope of work, inadequate communications during the
manipulations outside the documented scope of work, inadequate communications during the
Line 282: Line 287:
configurations on systems with the ability to impact safety were contributing factors to these
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
events. Rigorous adherence to process requirements for tracking components in an abnormal


configuration, even when current plant conditions allow such a configuration, helps maintain
configuration, even when current plant conditions allow such a configuration, helps maintain
Line 291: Line 296:


==CONTACT==
==CONTACT==
This IN requires no specific action or written response. Please direct any questions about this
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
matter to the technical contacts listed below or to the appropriate NRC Office of Nuclear
Line 297: Line 302:
Reactor Regulation (NRR) project manager.
Reactor Regulation (NRR) project manager.


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


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


Environmental Analysis                        Office of Nuclear Reactor Regulation
Robert M. Taylor


===Office of New Reactors===
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:===
===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


===Rebecca Sigmon, NRR===
JDoughtery
                        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
RSigmon


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


NAME    JDoughtery        RSigmon            AIssa          RElliott           BCurran
RElliott
 
BCurran


* w/edits
* 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
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


NAME    BBenney          TInverso            RTaylor        CMiller
5/6/2019
5/6/2019
5/24/2019
06/03/2019


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


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

Latest revision as of 04:06, 5 January 2025

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


ML19084A081 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 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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