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HomeNRC LibraryDocument CollectionsGeneric CommunicationsInformation Notices1993

# Information Notice No. 93-72: Observations from Recent Shutdown Risk and Outage Management Pilot Team Inspections

```
                                 UNITED STATES
                         NUCLEAR REGULATORY COMMISSION
                     OFFICE OF NUCLEAR REACTOR REGULATION
                            WASHINGTON, D.C.  20555

                              September 14, 1993

NRC INFORMATION NOTICE 93-72:  OBSERVATIONS FROM RECENT SHUTDOWN RISK AND      
                               OUTAGE MANAGEMENT PILOT TEAM INSPECTIONS

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 inform addressees of observations from recent shutdown risk and
outage management pilot team inspections.  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.

Background

Events that occurred during the past several years have caused the NRC staff
to be increasingly concerned about plant safety during shutdown operations. 
The Diablo Canyon event of April 10, 1987, in which boiling of the reactor
coolant resulted from a loss of decay heat removal, highlighted the fact that
operation of a pressurized-water reactor with a reduced reactor coolant system
(RCS) inventory is a particularly sensitive condition.  Based on its review of
that event, the staff issued Generic Letter 88-17, "Loss of Decay Heat
Removal," October 17, 1988, which requested that licensees address certain
generic deficiencies to improve safety during operations with a reduced RCS
inventory.  More recently, Incident Investigation Team report, NUREG-1410,
"Loss of Vital ac Power and the Residual Heat Removal System During Mid-Loop
Operations at Plant Vogtle Unit 1 on March 20, 1990," emphasized the need for
risk management of shutdown operations.  Discussions with foreign regulatory
organizations support NRC staff findings that the core-damage frequency for
shutdown operations may be a substantial fraction of the total core-damage
frequency.  

Description of Circumstances 

Between December 1991 and April 1993, the NRC staff conducted five pilot team
inspections to assess the effectiveness of industry initiatives for improving
shutdown safety.  The inspections were performed at Oconee Nuclear Station,
Unit 2 [NRC Inspection Report (IR) 50-270/91-202], Indian Point Nuclear 

9309090243.

                                                            IN 93-72
                                                            September 14, 1993
                                                            Page 2 of 4

Generating Station, Unit 3 (IR 50-286/92-901), Diablo Canyon Nuclear Station,
Unit 1 (IR 50-275/92-201), Prairie Island Nuclear Generating Plant, Units 1
and 2 (IR 50-282/92-201; 50-306/92-201), and Cooper Nuclear Station
(IR 50-298/93-201).  Approximately one week of each inspection focused on
licensee pre-outage planning and control processes and 8 to 10 days focused on
licensee implementation of the outage.  

In the pre-outage portion of the inspection, the inspectors evaluated the
following:  (1) management involvement in and oversight of the outage planning
process, (2) planning and scheduling of outage activities, especially the
relationships between significant work activities and the availability of
electrical power supplies, decay heat removal systems, reactor coolant system
RCS inventory and containment integrity, (3) the process for developing
individual work packages to ensure coordination with other activities, and (4)
operator response procedures, contingency plans and training for mitigation of
loss of decay heat removal capability, loss of RCS inventory and loss of
electrical power sources during shutdown conditions.

The inspectors walked through procedures related to shutdown safety to
determine if the specified activities could be accomplished in the allotted
time frames and to verify that the procedures could be implemented considering
probable equipment availability.  The inspectors reviewed training records on
outage procedures to determine if the training was adequate and that, when
appropriate, additional training was provided as the procedures were revised. 
The inspectors also evaluated the probable effects of environmental conditions
such as temperature, steam and flooding on the performance of activities that
would be required to mitigate adverse shutdown events.

In the implementation portion of the inspection, the inspectors evaluated:  
(1) the control of changes to the outage schedule, control of work activities,
and control of system alignments, (2) the working relationships and
communication channels between operations, maintenance and other plant support
personnel, (3) the conduct of operations personnel both inside and outside of
the control room regarding awareness of plant status, control of plant
evolutions, response to alarms and other abnormal indications, (4) the
completeness and effectiveness of shift turnovers, (5) whether maintenance and
modification work was performed in accordance with current written and
approved procedures and appropriate post-maintenance testing was required and
performed, and (6) the adequacy of management involvement and oversight of the
conduct of the outage as it progressed.

Other areas observed were, plant housekeeping, normal and emergency plant
lighting, configuration control, radiological controls, equipment labeling and
status tagging, vital area access control, use of overtime and licensee
control of contractor work including contractor training and qualifications.

Discussion 

In general, the inspectors found that licensees had instituted programmatic
changes developed from guidance contained in a Nuclear Management and
Resources Council document, NUMARC 91-06, "Guidelines for Industry Actions to.

                                                            IN 93-72
                                                            September 14, 1993
                                                            Page 3 of 4

Assess Shutdown Management."  The team inspectors found individual examples of
licensee failure to follow procedures but more importantly the inspectors
identified two areas of more general concern:  (1) risk assessment for
pre-outage planning, emergent work and schedule changes, and (2)
implementation of defense-in-depth methodologies for equipment availability. 
A general discussion of these areas is provided below.  Specific details of
the findings are contained in the inspection reports referenced above.

Risk Assessment for Pre-Outage Planning, Emergent Work and Schedule Changes 

The inspectors found that licensees used various programmatic controls to
assess shutdown risk factors during initial outage planning, emergent work and
schedule changes.  Assessment methodologies used for initial outage planning
ranged from following minimum guidelines for equipment availability to
performing a probabilistic risk assessment of scheduled outage activities. 
The inspection team found that the risk assessment aided the licensee in
identifying activities that would be subject to high risk during the scheduled
outage.  However, as the outage progressed, the risk assessment became less
valid because it was not updated as changes to the outage schedule occurred.  

In the areas of emergent work and schedule changes, the inspectors found that
three of the plants had a proceduralized process to assess the effect of
emergent work or schedule changes on plant risk.  The other two plants relied
on a functional review by planners, schedulers, and operators to adjust the
schedule appropriately to reduce risk.  

The inspectors found that all of the plants maintained status boards or
checklists in the control room to assist the operators in tracking the
configuration status of plant systems and to help identify potential
risk-significant activities.

Implementation of Defense-in-Depth for Equipment Availability

The inspection teams found that licensee implementation of defense-in-depth
for equipment availability was inconsistent.  Although industry guidelines for
declaring equipment "available" exist, the inspectors found that the criteria
for declaring equipment needed to ensure an appropriate margin of safety
"available" varied from licensee to licensee.  For example, declaring that
equipment was "available" did not always include ensuring that support systems
(e.g., cooling water and heating, ventilation and air conditioning) were also
available.  At times, after maintenance had been performed, equipment was
listed as "available" without the benefit of a post-maintenance functional
test.  The inspectors also found that some equipment was considered to be
"available" even though actions, such as removal of clearances or realignment
of valves, would be required before the equipment could perform its function.

In addition to the above concerns, at most of the plants the team inspectors
found examples of failures to comply with technical specification restrictions
on overtime work in that management approval to exceed overtime limits was
inadequately documented.  
.

                                                            IN 93-72
                                                            September 14, 1993
                                                            Page 4 of 4

Based on the five pilot inspections, the NRC inspection teams concluded that
NRC actions and industry initiatives have increased licensee awareness of the
risk associated with shutdown and low power conditions.  The inspection teams
found that licensees were aware of the necessity for ensuring that required
systems be available and of the need to maintain the capability of backup
equipment during an outage.  However, the inspection teams found that licensee
interpretations of industry initiatives for addressing shutdown risk varied
greatly.  This was demonstrated by the various licensee interpretations of
industry guidelines for declaring equipment "available."  

This information notice requires no specific action or written response.  If
you have any questions about the information in this notice, please contact
the technical contact listed below or the appropriate Office of Nuclear
Reactor Regulation (NRR) project manager.

                                    /s/'d by BKGrimes

                                    Brian K. Grimes, Director
                                    Division of Operating Reactor Support
                                    Office of Nuclear Reactor Regulation

Technical contact:  J.D. Wilcox, NRR
                    (301) 504-1262

Attachment:  
List of Recently Issued NRC Information Notices

.
```

*Page Last Reviewed/Updated Tuesday, November 12, 2013*

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