Home > NRC Library > Document Collections > Generic Communications > Information Notices > 1993 > IN 93­

72

Information Notice No. 93­72: 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