ML20151U485
| ML20151U485 | |
| Person / Time | |
|---|---|
| Site: | Rancho Seco |
| Issue date: | 07/31/1988 |
| From: | SACRAMENTO MUNICIPAL UTILITY DISTRICT |
| To: | |
| Shared Package | |
| ML20151U479 | List: |
| References | |
| NUDOCS 8808190121 | |
| Download: ML20151U485 (12) | |
Text
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l POWER ASCENSION MID-TERM ASSESSMENT OF PLANT OPERATIONS AND MAINTENANCE AND SCHEDULING ACTIVITIES July 1988 i
8808290121 880809
's
. DR ADOCK 05000312 PDC
s i
INTRODUCTION The Rancho Seco Power. Ascension-Program (depicted by the power profile provided'by Appendix A)-provides a deliberate and conservative approach to full power during which management can evaluate the plant, programs,.and people.
Safety is the primary consideration, with the explicit purpose of providing the operator and the supporting organizations'the experience in operating Rancho Seco at power.
The power plateau levels were selected to. provide low, medium and high power levels at which meaningful testing and training could be conducted.
The duration of the power plateaus was based upon providing sufficient time to conduct identified testing, operator experience enhancement and training, and administrative actions.
The Power Ascension Program provides experience contributing to the maturing of the operating staff and opportunities for i
management to ensure that an ' operating plant' attitude is reflected in the plant staffs' conduct of operations and work practices.
The Rancho Seco Power Ascension Program is conservative compared to other plants restarting from extended outages, notably TMI and Davis-Besse.
In May 1988, the Power Ascension profile (Appendix B) was adjusted to include a July outage of approximately 8-10 days.
This outage was planned to repair the flange gasket leak on the
'C' Reactor Coolant Pump (RCP) and to inspect and/or replace RCP studs exposed to resultant boric acid corrosion.
Although conservatively planned for July, the safety evaluation on the RCP stud, assuming a conservative linear corrosion rate, indicated that each RCP stud would not reach its minimum design diameter until November 1988, at the earliest.
Plant management directed that a mid-term assessment of the Power Ascension Program be conducted to evaluate how plant operations performance was satisfying restart program objectives, and if adjustments to the power ascension profile could be made consistent with the program objectives.
The results of the evaluation (contained herein) have thus far confirmed the readiness of the plant, programs and people-for return to operation.
In light of the successes of the program to date, prudent, minor adjustments to the power ascension profile may be made without compromising the objectives of the program.
(See Appendix C)
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I POWER ASCENSION MID-TERM ASSESSMENT PLANT OPERATIONS Since Rancho Seco returned to power operations, plant operators have gained significant experience while responding to several plant transients in a safe, effective and professional manner.
In preparation for the return to power operations, each operating crew received extensive experience with bringing the reactor critical.
Since initial restart criticality on March 30, 1988, and return to power operations on April 12, 1988, operations personnel were challenged by the following selected transients:
o On May 4, 1988, during the performance of STP.660 "Integrated Control System Tuning Program," the main turbine was manually tripped from 28% power in accordance with Section 6.30 "Turbine Trip Transient Monitoring."
The purpose of the turbine trip was to monitor the Integrated Control System (ICS) for proper response to the turbine trip.
After the turbine trip, three events occurred.
o The reactor tripped on overpressure.
o The
'A' letdown cocler relief valve lifted and caused a 1000 gallon Reactor Coolant System (RCS) discharge to the containment sump, The main generator output circuit breaker did not open o
within the expected time.
Subsequent analysis of the transient determined that a reactor trip with the plant conditions that existed, (i.e.,
the ICS response to the turbine trip and slightly reduced turbine bypass valve capacity) was a valid occurrence.
No deficiencies were observed in operator response to the unexpected reactor trip.
During the transient the relief valve for letdown cooler
'A' opened and did not reseat.
The relief valvo was isolated by operator action in the Control Room.
Approximately 1000 gallons of RCS inventory was released into the Reactor Building.
Subsequent investigation revealed that a discrepancy existed with the setpoint adjustment of the velve at ambient temperature conditions versus normal operating temperature.
Additional factors including elevation difference, setpoint and instrument tolerance, in addition to the temperature offset, accounted for premature lifting of the valve.
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l Based on a review of the trip data, it was apparent that the main generator output circuit breakers (OCBs) had tripped open 1 minute 14 seconds after turbine trip initiation.
The normal delay for OCB trip is approximately 45 secondo after turbine trip initiation.
Review of the OCB trip circuit and plant data indicated that the 45 second timer had been reset by procedurally implemented actions after the automatic trip.
The OCB trip circuit functioned as designed.
The combination of these events and complications were responded to by the operations crew in a prompt and correct manner as detailed in Licensee Event Report (LER) 88-08.
o Also on May 4, 1988, the planned Remote Shutdown Test was conducted in accordance with Special Test Procedure STP.1154.
Again, since this was a planned evolution, observation as well as hands-on training.was conducted.
Hands-on equipment experiences were shared to provide training benefit throughout the Operations Department.
The successful conduct of the test indicates a high level awareness of attention to detail.
o On May 12, 1988, the reactor was again taken critical, the turbine generator and secondary plant restarted, the main generator synchronized to the grid and power escalated to the 40% power plateau.
Plant response and power escalation was compared to expectations and discussed among appropriate plant personnel for experience transfer purposes, o
During power operations on May 12, 1988, the plant experienced an electrical grid upset.
The operators responded to this unanticipated transient in a safe, effective and professional manner by taking manual control of the turbine generator and stabilizing the plant.
Their prompt and correct actions are believed to have prevented a more significant transient.
o On May 15, 1988, following a feedwater pump speed control problem, plant operators took prompt, correct action in securing the
'B' main feedwater pump, preventing a steam generator overfeed condition.
This controlled corrective action prevented a more significant plant transient.
o On May 23, 1988, plant operators observed a high vibration indication on the main generator bearing.
Further evaluation and investigation revealed that the indicated high vibration on the main generator bearing was a result of arcing generator grounding brushes providing a faulty indication.
The false indication was corrected by replacing the defective grounding brushes.
The actions by the entire plant staff prevented an unnecessary plant transient.
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o On June 10, 1988, the plant experienced another electrical grid upset.
Once again, plant operators took manual control of the main turbine generator, stabilized the plant and avoided a more significant transient.
This upset provides another example of prompt corrective response to an unanticipated situation which provided additional experience to the plant operators, o
On June 29, 1988, a significant transient occurred which challenged the operators' attentiveness, training and confidence in taking deliberate action.
Both main feedwater block valves closed unexpectedly while the plant was producing 45% power.
The ICS successfully performed a reactor runback.to 25% power to match feedwater flow.
Operations personnel reacted swiftly to take necessary actions to stabilize the plant, reopen the block valves and manually increase plant power to about 35%. Following troubleshooting to determine the cause of'the transient, the plant was returned to 45% power.
Again, the prompt, safe and deliberate ections taken by the plant operators in controlling the plant during this event prevented a more severe transient.
o On June 30, 1988, the power system stabilizer failed, causing main generator output voltage oscillations.
Operators once again correctly assessed the situation, evaluated their options and took correct action in removing the stabilizer from service.
Their prompt action prevented a more serious transient from compromising safe plant operations.
During a power ascension program, abnormal circumstances and unique training opportunities are expected; therefore, the events discussed above and their diversity are not considered indicative of degraded plant performance.
In fact, the successful conduct of operators and their evident confidence in taking control of the plant provides assurance that experiences and lessons learned are successfully contributing to the enhanced training of the operating staff.
These results provide for increased confidence that correct, safe and reliable operation is being realized at Rancho Seco.
It must also be noted that during and before the 40% power plateau, extensive ICS tuning was performed.
This tuning necessitated placing the ICS in the manual mode, intensifying the requirement on operators to monitor and control the plant.
This ICS manual operation, over the course of several weeks, provided a unique ' hands-on' experience for operations personnel which added significantly to their experience base.
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In another area, effective interdepartmental coordination and communication continues to be demonstrated during the Power Ascension Program.
The daily Plan-of-the-Day (POD) meeting led l
l by the plant manager (AGM/NPP) has been effective in focusing the attention of each department manager on the support and actions required to sustain safe plant operations.
Through management policies and actions, including the POD meetings, the Nuclear Operations Department is clearly established as the director of plant activities with other departments performing support and service functions for operations.
In summary, plant operation during power ascension has provided unique opportunities and challenges for extensive ' hands-on' and
'one-of-a-kind' training enhancement, observation training and experiences.
The conservative restart power ascension program adopted by Rancho Seco Management continues to provide operations personnel with additional experience over a wide range of plant operating conditions.
These successful experiences enhance the operating staffs' ability to respond to operating situations in a safe, effective and professional manner.
MAINTENANCE AND SCHEDULING An important attribute of an operational organization is the 4
abflity to conduct maintenance outages in an efficient manner.
l Sir.ce restart, Rancho Seco has gained significant operational l
experience in scheduling and implementing equipment, system, and plant outages.
Formal written outage critiques are prepared for plant and major equipment outages to improve scheduling and implementation of future outages.
Overall, a review of maintenance and scheduling activities demonstrates that lessons are being learned from operational experiences, performance improvement is evident, and it is reasonable to expect continued
' lessons learned' improvements.
The Scheduling and Outage Management Department has established and defined a scheduling philosophy via its Department Directives.
Directives have been prepared specifically on the Scheduling Process, the Daily Scheduling Process, and the Equipment / Train Outage Process.
These Directives incorporate lessons learned from recent outages, and establish responsibilities to ensure outages are properly planned, coordinated, and critiqued.
A review of recent outage critiques indicates that responses to numerous substantive recommendations are being developed.
A recurring theme of these recommendations is that of establishing good communication and coordination between departments.
Some examples of results of these recommendations taken from recent critiques are:
better direction on who defines outage scopa j
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o more thorough pre-planning and detal. led scheduling o
better pre-outage, pre-job briefings j
o clear assignment of responsibilities and authorities (a specific example is outlined below)
The July 6, 1988 critique of the June TDI diesel outages i
established the following:
i The Maintenance Shift Supervisor (MSS) is responsible for the progression of outage work activities during i
the outage duration.
The Designated Outage Coordinator (DOC) is the focal point for all modifications to work packages, clearance boundaries, and outage work scope.
The group representative attending the Outage Coordination meeting shall have the authority to make agreements and take actions for his group and be responsible for ensuring that his work group is notified of these agreements / actions, improved tools for troubleshooting and root cause o
determinations o
pre-outage checklists o
greater outage visibility o
better coordination between Maintenance and Radiation Protection personnel (specific examples are outlined below)
The June 30, 1988 critique supplement of the May Planned Outage 1 (Pol) established the following:
Maintenance (planning) to work with Radiation Protection (RP) to improve task "locations."
This will ensure identification of precise work areas to permit proper RP surveys.
RP will evaluate implementing a grid location system.
RP to review and lay out basis plan to determine whether a thorough Reactor Building decon effort to reduce hot particle controls is worthwhile.
All departments are to review their personnel j
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_ qualifications for respirators, dosimetry, medical status and training prior to requesting entry to a work area.
o better pre-planning for contingencies (numerous exampics.
relating to both spare parts and additional personnel) i (specific examples are outlined below)
The May 24, 1988 critique of the Pol outage observed the-following:
no spare studs were staged for the OTSG manway leak
- repair, i
no spara studs or extra cap nutt were available prior to starting OTSG feedwater nozzls leak repair.
no spare snubbers were in the warehouse prior to 4
anubber inspection.
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replacement spares were not staged in containment prior to control rod position indication troubleshoot.
sufficient manpower resources were not available for 4
critical path work on Snubber Inspection and OTSG l
Feedwater Nozzle Leak Repair.
d better pre-outage review of training requirements; personnel o
qualifications available i
improvements in scheduling logistics, order of activities l
o and establishment of parallel work activities i
o procedure enhancements to improve efficiencies and maintain safety j
Many of these recommendations have been fully implemented and proven effective.
For example, several TDI diesel outages in i
April came close to exceeding allotted Lc0 time limits whereas recent TDI diesel outages have accomplished significant work well within allotted scheduled time.
The prevalent attitude i
emong plant personnel is to continue learning from the
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j experiences encountered and to continue performance improvament.
Many of the lessons learned have been applied to routine-maintenance activities.
Maintenance activities are coordinated i
with surveillance procedures on a cyclic schedule to minimize plant operability impacts.
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1 CONCLUSION
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The results of the Rancho Seco Power Ascension Program _ indicate that the deliberate and corrective approach to full power operations is providing the plant operators and supporting organizations enhanced training experiences operating at power.
The examples cited in the assessment provide evidence that the Power Ascension Program has ensured that an ' operating plant' attitude is reflected in the plant staffs' conduct of operations and work practices.
Operators' responses to the selected transients has provided evidence of lessons learned, enhanced training and confidence in taking deliberate corrective actions to preclude more significant plant transients.
These results provide for increased confidence that carrect, safe and reliable operation is being realized at Rancho fieco.
The lessons learned by maintenance, planning and scheduling critiques of planned outages have provided increased confidence that Rancho Seco personnel will continue learning from the experiences encountered and to continue performance improvemant.
The assessment concludes that prudent, minor adjustments to the power ascension profile may be made without compromising the objectives of the program.
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Appendfx A
. to Power Ascension Mid-Term Assessment l
POWER ASCENSION PROGRAM
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APPRO)0WATELY SIX (6) WONTHS DURATION
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i Ap'pendix 8 to Power Ascension Mid-Term Assessment POWER ASCENSION PROGRAM JUNE 29,1988 FULL POWER
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