Report on Fact-finding Meeting by Diablo Canyon Independent Safety Committee (DCISC) at Diablo Canyon Power Plant (DCPP) on May 4-5, 2006 by A. David Rossin, Member and Jim Booker, Consultant [16th Annual Report, Exhibit D.9]
1.0 Summary
The results of the May 4-5, 2006, Fact-finding trip to the Diablo Canyon Power Plant in Avila Beach, CA are presented. The subjects addressed and summarized in Section 3 include:
- Plant Tour 2R13 Outage
- Review 1st Quarter QPAR and QV Assessment of 2R13 Outage to Date
- Attend CARB Meeting
- Attend Outage Meeting
- Review Chemical & Volume Control System
- Meet with Plant Management
- Review AMSAC Status
2.0 Introduction
This Fact-finding trip to the DCPP was made to evaluate specific safety matters for the DCISC. The objective of the evaluation was to determine if PG&E’s performance is appropriate and determine if any areas revealed observations which are important enough to warrant further review, follow-up, or presentation at a public meeting. These safety matters include follow-up and/or continuing review efforts by the Committee, as well as those identified as a result of reviews of various safety-related documents.
Section 4—Conclusions highlights the conclusions of the Fact-finding team based on items reported in Section 3-Discussion. These highlights also include the team’s suggested follow-up items for the DCISC, such as scheduling future Fact-finding meetings on the topic, presentations at future public meetings, and requests for future updates or information from DCPP on specific areas of interest, etc.
Section 5—Recommendations list specific recommendations to PG&E proposed by the Fact-finding team. These recommendations will be considered by the DCISC. After review and approval by the DCISC, the Fact-finding report, including its recommendations, is provided to PG&E. The Fact-finding report will also appear in the DCISC Annual Report.
3.0 Discussion
3.1 Plant Tour 2R13 Outage
The DCISC Fact-finding Team was given a tour of the plant by Steve Hamilton, Engineer, Regulatory Services. The DCISC last toured the plant during a refueling outage during its November 9 & 10, 2005 Fact-finding Meeting (Reference 6.1).
The areas visited were the Turbine Building, Spent Fuel Building, Auxiliary Building and outside areas. Access to the Spent fuel Pool required radiation monitoring procedures. The Team was specifically interested in observing all the steps in the badging process.
The Team observed the work involved with the replacement of the low pressure turbine rotor. The low pressure rotors had been replaced and the inside shells were in place. The workers were making final connections in this area. The work area seemed to be in good condition considering the amount of working going on. There was no rigging work taking place during these observations.
In the Spent Fuel Building, technicians were visually inspecting a spent fuel bundle. They were trying to identify and characterize some scrapes on the outside fuel tubes to determine what caused them. They had also seen some similar scrapes on the fuel tubes on the opposite side of this bundle. Neither of these bundles were to be reinstalled in the reactor.
While discussing these inspections with DCPP personnel in the Spent Fuel Building, the Fact-finding Team was reminded by an RP technician that we should go to the lowest radiation area to continue our discussion which was a good practice by the RP Personnel.
In the Auxiliary Building, the Fact-finding Team observed RP personnel remotely monitoring (by closed TV) work in the Containment Building in high radiation areas. DCPP had started this practice in years past to reduce the radiation dose for RP Personnel while monitoring work in high radiation areas.
The Fact-finding Team observed work outside the buildings, including viewing work inside Containment through the equipment access door. This equipment access door will be used to transport the new steam generators when they are moved into the Containment Building. Overall, the work areas appeared to be in good condition even though much work was being performed.
- Conclusions:
- Overall the work being conducted during this tour during Outage 2R13 appeared to be satisfactory and well organized. Remote TV monitoring by the Radiation Protection (RP) personnel for work in high radiation areas is a good practice to reduce radiation dose. The reminder by the RP technician in the Spent Fuel Building to go to the lowest radiation area was also a good recommendation. The DCISC should continue to conduct tours of the plant during refueling outages.
3.2 Review 1st Quarter QPAR and QV Assessment of 2R13 Outage to Date
The DCISC Fact-finding Team met with Dave Taggart, Manager QV (Quality Verification), Jeff Hodges, Engineering QA (Quality Assurance) Supervisor, and Bob Prigmore, Plant QA Supervisor, to review the 1st Quarter Quality Performance Assessment Report (QPAR) and QV assessment of 2R13 outage. The DCISC last reviewed this activity at its January 18 & 19, 2006 Fact-finding Meeting (Reference 6.2).
Mr. Taggart now reports to Mr. Jack Keenan, Senior Vice President Generation. The 1st. Quarter QPAR was not issued yet, but Mr. Taggart discussed two areas that will be listed in the QPAR as needing management attention. These were 1) some INPO AFIs still are not resolved, and 2) Maintenance Work Packages DCPP is still having problems completing. DCPP will have an INPO evaluation early next year (2007) and an INPO mid-cycle review in July, 2006.
Mr. Taggart then reviewed the QV assessment of 2R13 performance during Windows 1 and 2 (April 17 to April 26, 2006). Overall, outage performance to date has been satisfactory. Shutdown activities went very well; RCS clean-up went well, resulting in a good reduction in source term. For example, steam generator bowl dose rates dropped an average of 12% from 2R12 to 2R13, from 4.2 R/hr. to 3.7 R/hr. Accrued dose is tracking under the estimate, and in some cases excellent focus to achieve ALARA resulted in significant reductions in expected dose.
Core off-load was performed satisfactorily, and Security logged events are trending to a new low. To date, Operations had experienced zero noteworthy errors, and clearances have been performed as scheduled.
The plant has experienced no recordable or disabling injuries during this period. (Later in the day at the Outage Meeting, one disabling injury and one recordable injury were reported. See Sec. 3.4 below.) However, a number of non-recordable injuries have occurred, in addition to non-injury "close calls." These near misses indicate that significant additional rigor and focus on safety is needed to curtail this trend.
Some activities have created additional challenges due to last-minute changes in plans. For example, the plan for fuel transfer cart cable replacement was changed, and the change had unforeseen negative consequences. Several hundred management observations were performed and documented during the period covering a wide variety of activities. In some areas, the observations were sufficiently self-critical to identify areas that needed improvement that could either be accomplished through coaching, or problems that warranted documentation in the corrective action system. However, other documented observations did not appear to utilize the same level of self-critical rigor, or did not document an identified problem in the corrective action system.
Through the first two windows of the outage, four noteworthy errors occurred, which is a reduction from the same period during the previous outage (five). The types of errors, however, are different from the previous outage, in that no clearance or test-related errors occurred. One involved improper entry into a high radiation area, and the remainder were maintenance related. The lower-level errors indicate a number of procedural misses and other attention-to-detail types of errors.
QV believes that the significant rigor and extensive management observations over the past year has resulted in improvements in work practices, and assisted management in identifying and resolving recurring problems. A review of the observations from this period indicates this good practice is continuing, and positive results are already evident.
Mr. Taggart reported that the Corrective Action Audit would be issued soon and that the audit identified some overdue quality problems. He also reported that an INPO Assist Visit in March, 2006 identified some problems with the Change Management Process. DCISC should review this audit and the INPO Assist Visit at a future Fact-finding meeting.
- Conclusions:
- It appears that Quality Verification continues to perform good assessments of performance of DCPP. The assessment during the outage identified areas where improvement has been made as well as areas that still need improvement. DCISC should review the Corrective Action Audit and the March 2006 INPO Assist Visit at a future Fact-finding meeting.
3.3 Attend CARB Meeting
The DCISC Fact-finding Team attended the Corrective Action Review Board (CARB) meeting to observe the conduct of the meeting. Those present were D. Jacobs- Chairperson, S. Ketelsen-Regulatory Services, P. Roller- Operations, K. Peters-Engineering, and T. King- Maintenance. An agenda for the meeting had been distributed before the meeting and all participations had reviewed the actions to be taken at this meeting. The CARB meets each week. The items to be discussed at the meeting were:
- A0643564 "Performance of OP B-3B1 Results in Incorrect Flow Path" CARB Apparent Cause Evaluation (ACE)
- N0002192 "Human Performance Cross-Cutting Issue", A0634178 "Corrective Action Effectiveness Review for NCR N0002192", Review/Concur Interim Corrective Action Effectiveness
- A0637739 "NSOC – CAP Oversight Subcommittee Actions", Review NSOC Subcommittee Recommendations.
- CARB ACE, Determine List of ACE’s for Future Review.
- Q0012346 "Breaker 52-PY2229 Failed to De-energize After Opening."
They reviewed the AR’s for problem description, cause analysis, and corrective action. They also reviewed requests for Corrective Action Due Date extensions. The members of CARB discussed each of these items in detail and came to agreement by all as to what actions need to be taken. One of the ARs was to be updated or revised and reviewed again by CARB. The CARB reviewed action items identified at this meeting to be sure they are addressed at a future meeting.
- Conclusions:
- The Corrective Action Review Board (CARB) agenda was prepared prior to the meeting and it appeared that each of the members had reviewed the information to participate in the discussion for each of the items. The CARB’s review of the AR’s for problem description, cause analysis and corrective action was very detailed and the discussion was open. Action decisions were taken.
3.4 Attend 2R13 Outage Meeting
The DCISC Fact-finding Team attended the afternoon 2R13 Outage Meeting. The DCISC Teams have attended other outage meeting (the last one being 1R13) when Fact-finding meetings were scheduled during an outage. This is a large meeting, with about 50 people in attendance. The meeting was conducted by Brad Hinds, Outage Director He reported an update on injuries. A worker had a disabling injury when he was climbing stairs carrying a light load and his knee gave way. He did not fall, slip, trip or anything; he just felt pain in his knee. He will be off work for a few days. An in-depth evaluation was undertaken concerning the proper category for this injury. The evaluators reached agreement that it had to be declared as a "disabling injury."
In addition, an injury that occurred back on April 25, 2006 has recently been classified as recordable. This involved a worker who was guiding a rolling load and fell when the load shifted, causing a hairline fracture of the arm.
Mr. Hinds reviewed the schedule and what needed to be done to bring the schedule up to date. He also went over items reported as complete and discussed some problems that still had to be faced. The Low Pressure Turbine rotor replacement work is on schedule and some of that work is complete.
Each department reported on its schedule and noted the items it had completed. The critical path work was discussed and other jobs that were close to critical path were mentioned. They were all urged to do their best for the schedule, but were reminded to do work safely and correctly with no errors. The meeting was short and efficient, but enough information was discussed for everyone to keep informed of scope of work and schedule.
- Conclusions:
- The 2R13 outage meeting appeared to be effective in terms of informing everyone as to what had been accomplished and what was needed to keep on schedule. The managers emphasized the importance of working safely and correctly.
3.5 Review Chemical & Volume Control System
The DCISC Fact-finding Team met with Bruce Tripp, Senior Engineer – CVCS & NSSS System Engineer, to discuss the Chemical & Volume Control System (CVCS). The System Health Report lists these systems as Yellow (unsatisfactory performance) for Units 1 & 2. Their forecasted date to reach the DCPP expected performance goal is 2R15. The system has been Yellow for a short period of time as a result of changes in the grading system for health reports.
- Mr. Tripp reviewed the System Health Report (SHR) which listed many problems. This SHR was issued on April 12, 2006 (before 2R13). These problems are:
- Reactor Coolant System (RCS) letdown pressure control valve CVCS-1-PCV-135, allows letdown pressure to oscillate after RCS dilution operations. Troubleshooting is planned for 1R14. Currently, there are no immediate corrective actions identified.
- Centrifugal Charging Pump (CCP) 2-1 entered Alert status on 7/15/03 due to high outboard bearing vibration in the horizontal direction. The vibration is caused by structural resonance and an imbalance in the rotating assembly. Structural modifications to the pump pedestal and replacement of the rotating assembly will be done in 2R13.
- CCP 2-2 entered the Alert status on 9/30/05 due to high outboard bearing vibration in the horizontal direction. The vibration was measured at 0.343 in/sec. The Alert limit is 0.325 in/sec and the Action limit is 0.700 in/sec. Troubleshooting is in process. The likely correction action may include stiffening of the pump base. Estimated completion date is Outage 2R14.
- RCS makeup control switch 43-MU operation causes steam generator pressure on recorder #7 to change. Extensive troubleshooting has not identified the cause of the problem. Cable "cross-talk" is suspected. Replacement of the RCS makeup control system in 2R14 may resolve this problem.
- RCS makeup primary water integrator, YIC-111 for both units overruns the amount of makeup demanded by approximately 3 gallons. This is due to the design limitations of the control loop and flow control valves. This issue will be resolved by replacing the primary water flow meter, the flow control valves, the control loop, and operator controls in Outages 1R14 and 2R14.
- The INPO Performance Index for High Pressure Safety Injection Unavailability for DCPP Unit 1 & 2 is not in the industry best quartile. The DCPP index is currently in the median quartile. High Pressure Safety Injection includes SIPs and CCPs. Achieving best quartile unavailability will require eliminating one mid-cycle MOW for each pump and returning the Unit 2 CCP’s to good health. Estimated completion date is June, 2009.
- CCP 2-2 exceeded the Alert limit on 4/15/05 for outboard bearing vibration in the vertical direction. The measured vibration and the Alert limit is 0.062 in/sec. The Action limit is 0.150 in/sec. An investigation is in process and estimated completion date is 2R14.
Industry experience with shaft cracking in CCPs is not good. DCPP has scheduled the replacement of one of the CCPs in 2R13 and will replace one CCP for each unit refueling outage until all have been replaced in 2R15. If they were to have a cracked shaft in one of the pumps, and only have one pump available, then they have 72 hours to repair, replace the pump or shut the unit down. They are asking for a Technical Specification revision for 7 days time allowed. They have a spare shaft which will be put in one of the Unit 2 pumps in 2R13. They will use old internals for spare while they order a new spare assembly.
Mr. Tripp reported that the System Health report is reviewed each month with his supervisor and once a year (scheduled for June, 2006) with the Plant Health Committee.
- Conclusions:
- The System Health Report for the Chemical & Volume Control System lists many problems which have been in existence for a long period of time. It appears that DCPP is now taking action to resolve these issues, but is taking a long time to correct them.
3.6 DCISC Member Meeting with Plant Management
Dr. Rossin, DCISC Member, met with Jim Becker, VP DCPP Operations & Station Director, to discuss items reviewed in the Fact-finding meeting and other items of interest.
3.7 Review AMSAC Status
The DCISC Fact-finding Team met with Jose Medina, System Engineer to discuss the status of the Anticipated Transient without Scram Mitigation System (AMSAC). The System Health report for this system is rated as Yellow (unsatisfactory). The reason for being rated Yellow is that AMSAC requires a 20 minute battery backup power supply be available for operational when the EJUPS is swapped to bypass (auto or manual) or placed in its "alternate" AC power supply, and the EJUPS battery is not currently available to provide this 20 minutes backup.
Mr. Medina reported that obsolescence is becoming an issue. Some circuit boards are not manufactured anymore. The system has been performing well, but when it does break, it is becoming difficult to fix and troubleshoot. At this point there are sufficient spare parts. A plan has been developed and evaluated to replace this system in the I&C Long Term Strategy development document.
AR A0661877 has been issued to the AMSAC UPS, and a completion date of December 30, 2006 was selected. The System Health Report for this system is not as detailed or complete as other SHRs the DCISC has reviewed.
- Conclusions:
- The System Health Report (SHR) for the Anticipated Transient without Scram Mitigation System (AMSAC) is rated Yellow (unsatisfactory), and an AR has been issued to resolve the problem. A completion date of December 30, 2006 was scheduled. The SHR for this system is not as detailed and complete to describe the problem and corrective action as other SHR the DSIC have reviewed.
4.0 Conclusions
- 4.1
- Overall the work being conducted during this tour during Outage 2R13 appeared to be satisfactory and well organized. Remote TV monitoring by the Radiation Protection (RP) personnel for work in high radiation areas is a good practice to reduce radiation dose. The reminder by the RP technician in the Spent Fuel Building to go to the lowest radiation area was also a good recommendation. The DCISC should continue to conduct tours of the plant during refueling outages.
- 4.2
- It appears that Quality Verification continues to perform good assessments of performance of DCPP. The assessment during the outage identified areas where improvement has been made as well as areas that still need improvement. DCISC should review the Corrective Action Audit and the March 2006 INPO Assist Visit at a future Fact-finding meeting.
- 4.3
- The Corrective Action Review Board (CARB) agenda was prepared prior to the meeting and it appeared that each of the members had reviewed the information to participate in the discussion of each of the items. The CARB’s review of the AR’s for problem description, cause analysis and corrective action was very detailed and the discussion was open. Action decisions were taken.
- 4.4
- The 2R13 outage meeting appeared to be effective in terms of informing everyone as to what had been accomplished and what was needed to keep on schedule. The managers emphasized the importance of working safely and correctly.
- 4.5
- The System Health Report for the Chemical & Volume Control System lists many problems which have been in existence for a long period of time. It appears that DCPP is now taking action to resolve these issues, but is taking a long time to correct them.
- 4.6
- The System Health Report (SHR) for the Anticipated Transient without Scram Mitigation System (AMSAC) is rated Yellow (unsatisfactory), and an AR has been issued to resolve the problem. A completion date of December 30, 2006 was scheduled. The SHR for this system is not as detailed and complete to describe the problem and corrective action as other SHR the DSIC have reviewed.
- 5.0 Recommendations
- None
- 6.0 References
- 6.1 “Diablo Canyon Independent Safety Committee Fifteenth Annual Report on the Safety of Diablo Canyon Nuclear Power Plant Operations, July 1, 2004 – June 30, 2005”, Approved October 12, 2005, Exhibit D.4, Section 3.6, “Tour of DCPP During 1R13.”
- 6.2 Ibid., Exhibit D.6, Section 3.7, “Quality Verification Update (QPAR).”