IR 05000275/2016001
| ML16117A512 | |
| Person / Time | |
|---|---|
| Site: | Diablo Canyon  |
| Issue date: | 04/26/2016 |
| From: | Jeremy Groom NRC/RGN-IV/DRP/RPB-A |
| To: | Halpin E Pacific Gas & Electric Co |
| Groom J | |
| References | |
| IR 2016001 | |
| Download: ML16117A512 (32) | |
Text
UNITED STATES ril 26, 2016
SUBJECT:
DIABLO CANYON POWER PLANT - NRC INSPECTION REPORT 05000275/2016001 AND 05000323/2016001
Dear Mr. Halpin:
On March 31, 2016, the U.S. Nuclear Regulatory Commission (NRC) completed an inspection at your Diablo Canyon Power Plant, Units 1 and 2. On April 7, 2016, the NRC inspectors discussed the results of this inspection with you and other members of your staff. Inspectors documented the results of this inspection in the enclosed inspection report.
NRC inspectors documented one finding of very low safety significance (Green) in this report.
This finding involved a violation of NRC requirements. The NRC is treating this violation as non-cited violation (NCV) consistent with Section 2.3.2.a of the NRC Enforcement Policy.
If you contest the violation or significance of the NCV, you should provide a response within 30 days of the date of this inspection report, with the basis for your denial, to the U.S. Nuclear Regulatory Commission, ATTN: Document Control Desk, Washington, DC 20555-0001; with copies to the Regional Administrator, Region IV; the Director, Office of Enforcement, U.S. Nuclear Regulatory Commission, Washington, DC 20555-0001; and the NRC resident inspector at the Diablo Canyon Power Plant.
In accordance with Title 10 of the Code of Federal Regulations (10 CFR) 2.390, Public Inspections, Exemptions, Requests for Withholding, a copy of this letter, its enclosure, and your response (if any) will be available electronically for public inspection in the NRCs Public Document Room or from the Publicly Available Records (PARS) component of the NRC's Agencywide Documents Access and Management System (ADAMS). ADAMS is accessible from the NRC Web site at http://www.nrc.gov/reading-rm/adams.html (the Public Electronic Reading Room).
Sincerely,
/RA/
Jeremy R. Groom, Chief Project Branch A Division of Reactor Projects Docket Nos. 50-275 and 50-323 License Nos. DPR-80 and DPR-82
Enclosure:
Inspection Report 05000275/2016001 and 05000323/2016001 w/ Attachment: Supplemental Information
REGION IV==
Docket: 05000275; 05000323 License: DPR-80; DPR-82 Report: 05000275/2016001; 05000323/2016001 Licensee: Pacific Gas and Electric Company Facility: Diablo Canyon Power Plant, Units 1 and 2 Location: 7 1/2 miles NW of Avila Beach Avila Beach, CA Dates: January 1 through March 31, 2016 Inspectors: B. Tharakan, Senior Resident Inspector J. Reynoso, Resident Inspector G. L. Guerra, CHP, Emergency Preparedness Inspector T. Sullivan, Project Engineer Approved Jeremy Groom By: Chief, Project Branch A Division of Reactor Projects-1- Enclosure
SUMMARY
IR 05000275/2016001, 05000323/2016001; 01/01/2016 - 03/31/2016; Diablo Canyon Power
Plant; Problem Identification and Resolution.
The inspection activities described in this report were performed between January 1 and March 31, 2016, by the resident inspectors at Diablo Canyon Power Plan and inspectors from the NRCs Region IV office. One finding of very low safety significance (Green) is documented in this report. This finding involved a violation of NRC requirements. The significance of inspection findings is indicated by their color (Green, White, Yellow, or Red), which is determined using Inspection Manual Chapter 0609, Significance Determination Process. Their cross-cutting aspects are determined using Inspection Manual Chapter 0310, Aspects within the Cross-Cutting Areas. Violations of NRC requirements are dispositioned in accordance with the NRC Enforcement Policy. The NRCs program for overseeing the safe operation of commercial nuclear power reactors is described in NUREG-1649, Reactor Oversight Process.
Cornerstone: Mitigating Systems
- Green.
The inspectors identified a non-cited violation of 10 CFR Part 50, Appendix B,
Criterion III, Design Control, for the failure to verify the design adequacy of the safety-related ventilation system for the 480-volt AC switchgear and 125-volt DC inverter rooms. Specifically, the licensee failed to verify sufficient ventilation system airflow to ensure the temperature in rooms housing safety-related electrical equipment remained below 104 degrees Fahrenheit. The licensees corrective actions were documented in Notification 50840266.
The failure to provide design control measures to verify the adequacy of the 480-volt AC switchgear and 125-volt DC inverter rooms ventilation system design was a performance deficiency. The performance deficiency was more than minor because it was associated with the design control attribute of the Mitigating Systems Cornerstone and adversely affected the cornerstone objective to ensure the availability, reliability, and capability of systems that respond to initiating events to prevent undesirable consequences. Specifically, the reduction in airflow to the rooms impacts the reliability of the safety-related equipment ventilation system to maintain the temperatures in these rooms below design limits for the duration of all accident scenarios. Using NRC Inspection Manual Chapter 0609,
Appendix A, Exhibit 2, Mitigating Systems Screening Questions, the inspectors determined the finding was of very low safety significance because (1) the finding was not a deficiency affecting the design or qualification of a mitigating system; (2) the finding did not represent a loss of system and/or function; (3) the finding did not represent an actual loss of function of a single train for greater than its technical specification allowed outage time; and (4) the finding does not represent an actual loss of function of one or more non-technical specification trains of equipment designated as high safety-significant in accordance with the licensees maintenance rule program for greater than 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />.
The inspectors determined that this finding did not have a cross-cutting aspect because the most significant contributor of this finding occurred more than three years ago, and is therefore, not representative of current licensee performance (Section 4OA2.2).
PLANT STATUS
Units 1 and 2 operated at or near full power for the duration of this inspection period.
REPORT DETAILS
REACTOR SAFETY
Cornerstones: Initiating Events, Mitigating Systems, and Barrier Integrity
1R01 Adverse Weather Protection
Readiness for Impending Adverse Weather Conditions
a. Inspection Scope
On January 6, 2016, the inspectors completed an inspection of the stations readiness for impending adverse weather conditions. The inspectors reviewed plant design features, the licensees procedures to respond to heavy rains and high winds, and the licensees planned implementation of these procedures. The inspectors evaluated operator staffing and accessibility of controls and indications for those systems required to control the plant.
These activities constituted one sample of readiness for impending adverse weather conditions, as defined in Inspection Procedure 71111.01.
b. Findings
No findings were identified.
1R04 Equipment Alignment
.1 Partial Walk-down
a. Inspection Scope
The inspectors performed partial system walk-downs of the following risk-significant systems:
- February 23, 2016, Unit 2, emergency diesel generator 2-3, partial alignment of lube oil, fuel oil, and starting air systems
- March 15, 2016, Unit 1, emergency diesel generator 1-3, partial alignment of electrical, fuel oil, and starting air systems
- March 24, 2016, Unit 1, auxiliary feedwater pump 1-2
- March 30, 2016, Unit 2, emergency diesel generator 2-2, partial alignment The inspectors reviewed the licensees procedures and system design information to determine the correct lineup for the systems. They visually verified that critical portions of the systems were correctly aligned for the existing plant configuration.
These activities constituted four partial system walk-down samples as defined in Inspection Procedure 71111.04.
b. Findings
No findings were identified.
.2 Complete Walk-down
a. Inspection Scope
On March 9, 2016, the inspectors performed a complete system walk-down inspection of the emergency diesel generator 1-2. The inspectors reviewed the licensees procedures and system design information to determine the correct emergency AC electrical power system lineup for the existing plant configuration. The inspectors also reviewed outstanding work orders, open condition reports, in-process design changes, temporary modifications, and other open items tracked by the licensees operations and engineering departments. The inspectors then visually verified that the system was correctly aligned for the existing plant configuration.
These activities constituted one complete system walk-down sample, as defined in Inspection Procedure 71111.04.
b. Findings
No findings were identified.
1R05 Fire Protection
Quarterly Inspection
a. Inspection Scope
The inspectors evaluated the licensees fire protection program for operational status and material condition. The inspectors focused their inspection on four plant areas important to safety:
- January 27-28, 2016, Unit 1, 4.16 kV switchgear rooms within fire areas TB-4, TB-5, and TB-6; in the turbine building 119 foot elevation
- February 4, 2016, Unit 1, emergency diesel generator rooms within fire areas TB-1, TB-2, and TB-3; in the turbine building 85 foot elevation
- February 26, 2016, Unit 2, emergency diesel generators 2-1, 2-2, 2-3, Fire Areas TB-8, TB-9, and TB-17
- February 26, 2016, Unit 2, 4.16 kV and 12 kV switchgear and cable rooms within fire areas TB-10, TB-11, TB-12, TB-13, and Fire Area 20 For each area, the inspectors evaluated the fire plan against defined hazards and defense-in-depth features in the licensees fire protection program. The inspectors evaluated control of transient combustibles and ignition sources, fire detection and suppression systems, manual firefighting equipment and capability, passive fire protection features, and compensatory measures for degraded conditions.
These activities constituted four quarterly inspection samples, as defined in Inspection Procedure 71111.05.
b. Findings
No findings were identified.
1R06 Flood Protection Measures
a. Inspection Scope
On March 14, 2016, the inspectors completed an inspection of the stations ability to mitigate flooding due to internal causes. After reviewing the licensees flooding analysis, the inspectors chose one plant area containing risk-significant structures, systems, and components that were susceptible to flooding:
- Unit 1, safety injection pump rooms 1-1 and 1-2 The inspectors reviewed plant design features and licensee procedures for coping with internal flooding. The inspectors walked down the selected areas to inspect the design features, including the material condition of seals, drains, and flood barriers. The inspectors evaluated whether operator actions credited for flood mitigation could be successfully accomplished.
These activities constituted completion of one flood protection measures sample, as defined in Inspection Procedure 71111.06.
b. Findings
No findings were identified.
1R07 Heat Sink Performance
a. Inspection Scope
On March 14, 2016, the inspectors completed an inspection of the readiness and availability of risk-significant heat exchangers. The inspectors reviewed the data from a performance test for the Unit 1 component cooling water heat exchangers. Additionally, the inspectors walked down the heat exchangers to observe their performance and material condition.
These activities constituted completion of one heat sink performance annual review sample, as defined in Inspection Procedure 71111.07.
b. Findings
No findings were identified.
1R11 Licensed Operator Requalification Program and Licensed Operator Performance
.1 Review of Licensed Operator Requalification
a. Inspection Scope
On March 17, 2016, the inspectors observed simulator training for an operating crew.
The inspectors assessed the performance of the operators and the evaluators critique of their performance. The inspectors also assessed the modeling and performance of the simulator during the simulator training scenario.
These activities constituted completion of one quarterly licensed operator requalification program sample, as defined in Inspection Procedure 71111.11.
b. Findings
No findings were identified.
.2 Review of Licensed Operator Performance
a. Inspection Scope
The inspectors observed the performance of on-shift licensed operators in the plants main control room. At the time of the observations, the plant was in a period of heightened activity due to emergency diesel generator 2-2 out of service. The inspectors observed the operators performance of the following activities:
- March 2-3, 2016, Unit 2, emergency diesel generator 2-2; under voltage, over-speed trip and full load testing following a major maintenance outage In addition, the inspectors assessed the operators adherence to plant procedures, including the conduct of operations procedure and other operations department policies.
These activities constituted completion of one quarterly licensed operator performance sample, as defined in Inspection Procedure 71111.11.
b. Findings
No findings were identified.
1R12 Maintenance Effectiveness
a. Inspection Scope
The inspectors reviewed two instance of degraded performance or condition of safety-related structures, systems, and components (SSCs):
- February 24-29, 2016, Unit 2, emergency diesel generator 2-2 damaged fuel camshaft 3L replacement
- March 8, 2016, Unit 2, emergency diesel generator lube oil system leakage, Notification 50664392 The inspectors reviewed the extent of condition of possible common cause SSC failures and evaluated the adequacy of the licensees corrective actions. The inspectors reviewed the licensees work practices to evaluate whether these may have played a role in the degradation of the SSCs. The inspectors assessed the licensees characterization of the degradation in accordance with 10 CFR 50.65 (the Maintenance Rule), and verified that the licensee was appropriately tracking degraded performance and conditions in accordance with the Maintenance Rule.
These activities constituted completion of two maintenance effectiveness samples, as defined in Inspection Procedure 71111.12.
b. Findings
No findings were identified.
1R13 Maintenance Risk Assessments and Emergent Work Control
a. Inspection Scope
The inspectors reviewed four risk assessments performed by the licensee prior to changes in plant configuration and the risk management actions taken by the licensee in response to elevated risk:
- January 20, 2016, Unit 1, component cooling water pump 1-3 and residual heat removal pump 1-1 motor oil leaks
- February 8-12, 2016, Unit 1, auxiliary saltwater traveling screen 1-7 head section overhaul
- February 29 - March 3, 2016, Unit 2, emergency diesel generator 2-2 extended online maintenance
- March 29, 2016, Unit 2, emergency diesel generator 2-1 extended online maintenance The inspectors verified that these risk assessments were performed timely and in accordance with the requirements of 10 CFR 50.65 (the Maintenance Rule) and plant procedures. The inspectors reviewed the accuracy and completeness of the licensees risk assessments and verified that the licensee implemented appropriate risk management actions based on the result of the assessments.
Additionally, on February 10, 2016, the inspectors observed the licensees response to the Unit 1 nuclear instrument NI-43 high flux rate and high flux bistables tripped condition during flux mapping per Notification 50834245. The inspectors also observed portions of this emergent work activity that had the potential to cause an initiating event.
The inspectors verified that the licensee appropriately developed and followed a work plan for these activities. The inspectors verified that the licensee took precautions to minimize the impact of the work activities on unaffected SSCs.
These activities constituted completion of five maintenance risk assessments and emergent work control inspection samples, as defined in Inspection Procedure 71111.13.
b. Findings
No findings were identified.
1R15 Operability Determinations and Functionality Assessments
a. Inspection Scope
The inspectors reviewed six operability determinations that the licensee performed for degraded or nonconforming SSCs:
- January 5-6, 2016, Units 1 and 2, operability determination of vital AC power inverters associated with replacement of panel light sockets
- January 13, 2016, Unit 1, operability determination of nuclear instrument NI-42 axial offset anomaly per Notification 50829002
- January 26, 2016, Unit 1, operability determination of component cooling water pump 1-3 high oil consumption per Notification 50822102
- February 29 - March 1, 2016, Unit 2, operability determination of emergency diesel generator 2-3, jacket water and lube oil system leakage
- March 18, 2016, Unit 2, operability determination of containment fan cooler 2-3 due to high vibration per Notifications 50831742 and 50826542
- March 23, 2016, Unit 2, operability determination of emergency diesel generator 2-2 jacket water high temperature annunciator lit per Notification 50840728 The inspectors reviewed the timeliness and technical adequacy of the licensees evaluations. Where the licensee determined the degraded SSC to be operable, the inspectors verified that the licensees compensatory measures were appropriate to provide reasonable assurance of operability. The inspectors verified that the licensee had considered the effect of other degraded conditions on the operability of the degraded SSC.
These activities constituted completion of six operability and functionality review samples as defined in Inspection Procedure 71111.15.
b. Findings
No findings were identified.
1R18 Plant Modifications
a. Inspection Scope
On February 2-3, 2016, the inspectors reviewed a permanent modification on Unit 1 to modify the charging pump gear oil pump discharge strainer per Notification 50700075.
The inspectors reviewed the design and implementation of the modification. The inspectors verified that work activities involved in implementing the modification did not adversely impact operator actions that may be required in response to an emergency or other unplanned event. The inspectors verified that post-modification testing was adequate to establish the operability of the SSC as modified.
These activities constituted completion of one sample of permanent modifications, as defined in Inspection Procedure 71111.18.
b. Findings
No findings were identified.
1R19 Post-Maintenance Testing
a. Inspection Scope
The inspectors reviewed six post-maintenance testing activities that affected risk-significant SSCs:
- January 7, 2016, Unit 2, post-maintenance test of auxiliary saltwater cooling pump 2-2 and component cooling water heat exchanger 2-2 following heat exchanger repairs and motor maintenance under Work Order 64094268
- February 4, 2016, Unit 1, auxiliary saltwater (ASW) pump 1-2 return to service test following maintenance on ASW pump discharge line vacuum relief valve SW-1-302 per maintenance under Work Order 60079216
- February 16, 2016, Unit 1, post-maintenance test of emergency diesel generator 1-3, jacket water heater replacement, maintenance under Work Order 60084944
- March 3, 2016, Unit 2, post-maintenance test of emergency diesel generator 2-2 following major overhaul of engine components under Work Order 60070644
- March 14-15, 2016, Unit 2, reactor cavity sump level transmitter channel, LT-62, functional testing following maintenance under Work Order 64142543
- March 15-16, 2016, Unit 2, post-maintenance test of emergency diesel generator 2-3, fuel injector replacements, maintenance under Work Order 64038680 The inspectors reviewed licensing- and design-basis documents for the SSCs and the maintenance and post-maintenance test procedures. The inspectors observed the performance of the post-maintenance tests to verify that the licensee performed the tests in accordance with approved procedures, satisfied the established acceptance criteria, and restored the operability of the affected SSCs.
These activities constituted completion of six post-maintenance testing inspection samples, as defined in Inspection Procedure 71111.19.
b. Findings
No findings were identified.
1R22 Surveillance Testing
a. Inspection Scope
The inspectors observed four risk-significant surveillance tests and reviewed test results to verify that these tests adequately demonstrated that the SSCs were capable of performing their safety functions:
In-service tests:
- February 5, 2016, Unit 2, surveillance test of containment spray pump 2-1 Reactor coolant system leak detection tests:
- March 30, 2016, Units 1 and 2, reactor coolant system leakage test Other surveillance tests:
- January 8, 2016, Unit 2, emergency diesel generator 2-1, routine surveillance and engine analysis testing
- March 3, 2016, Unit 2, full load rejection test of emergency diesel generator 2-2 The inspectors verified that these tests met technical specification requirements, that the licensee performed the tests in accordance with their procedures, and that the results of the test satisfied appropriate acceptance criteria. The inspectors verified that the licensee restored the operability of the affected SSCs following testing.
These activities constituted completion of four surveillance testing inspection samples, as defined in Inspection Procedure 71111.22.
b. Findings
No findings were identified.
Cornerstone: Emergency Preparedness
1EP4 Emergency Action Level and Emergency Plan Changes
a. Inspection Scope
The inspector performed an in-office review of changes to Diablo Canyon Power Plant Emergency Plan and Emergency Plan Implementing Procedures. Specifically, the inspector reviewed:
- Emergency Plan Section 5, Organizational Control of Emergencies, Revision 4.16. This revision clarified that emergency medical technician-qualified firefighters are available at all times, clarified the functions of the Emergency Operations Facility, and replaced the requirement for a medical panel with agreements with local hospitals and the Radiation Emergency Assistance Center/Training Site (REACTS).
- Emergency Plan Section 5, Organizational Control of Emergencies, Revision 4.17. This revision defined who can fill the shift technical advisor function and made minor administrative corrections and changes.
- Emergency Plan Section 6, Emergency Measures, Revision 4.16. This revision clarified the use of the on-site emergency signal, removed the reference to the medical panel in support of REACTS, clarified the framework for industry support, and clarified training requirements for decontamination techniques.
- Emergency Plan Section 6, Emergency Measures, Revision 4.17. This revision restored text that was inadvertently removed in revision 3.20 regarding the calculation of release rate and made other editorial changes.
- Emergency Plan Section 7, Emergency Facilities and Equipment, Revision 4.20. This revision restored language from the approved safety evaluation report on minimum technical support center occupancy, removed statements referring to maintaining facilities specifically for corporate support personnel, updated the description of firefighting capabilities, and added a specific reference to where commitments for respiratory protection equipment numbers are located.
- Emergency Plan Section 8, Maintaining Emergency Preparedness, Revision 4.13. This revision restored language from the approved safety evaluation report requiring the performance of verifying telephone number contacts on a quarterly basis.
- Emergency Plan Section 8, Maintaining Emergency Preparedness, Revision 4.14. This revision clarified how training is provide to offsite medical providers, updated the frequency of performing an ingestion pathway exercise, and made other editorial changes.
- Emergency Plan Appendix B, Offsite Agency Support Documents, Revision 4.02. This revision made an editorial name change.
- Emergency Plan Appendix F, ERO On-Shift Staffing Analysis Report, Revision 4.03. This revision updated an incorrect procedure reference.
- Emergency Plan Appendix G, Protective Action Recommendation Strategy Bases, Revision 4.01. This revision made editorial name changes for offsite response organizations.
- EPIP EP RB-10, Protective Action Recommendations, Revision 19. Revised to emphasize that decision makers are responsible for determining and approving protective action recommendations.
These revisions were compared to previous revisions, to the criteria of NUREG-0654, Criteria for Preparation and Evaluation of Radiological Emergency Response Plans and Preparedness in Support of Nuclear Power Plants, Revision 1, and to the standards in 10 CFR 50.47(b) to determine if the revision adequately implemented the requirements of 10 CFR 50.54(q)(3) and 50.54(q)(4). The inspector verified that the revisions did not reduce the effectiveness of the emergency plan. This review was not documented in a safety evaluation report and did not constitute approval of licensee-generated changes; therefore, the revisions are subject to future inspection.
These activities constituted completion of 11 emergency action level and emergency plan changes samples as defined in Inspection Procedure 71114.04.
b. Findings
No findings were identified.
1EP6 Drill Evaluation
Emergency Preparedness Drill Observation
a. Inspection Scope
The inspectors observed an emergency preparedness drill on January 27, 2016, to verify the adequacy and capability of the licensees assessment of drill performance. The inspectors reviewed the drill scenario, observed the drill from the technical support center, simulator, and attended the post-drill critique. The inspectors verified that the licensees emergency classifications, off-site notifications, and protective action recommendations were appropriate and timely. The inspectors verified that any emergency preparedness weaknesses were appropriately identified by the licensee in the post-drill critique and entered into the corrective action program for resolution.
These activities constituted completion of one emergency preparedness drill observation sample, as defined in Inspection Procedure 71114.06.
b. Findings
No findings were identified.
OTHER ACTIVITIES
Cornerstones: Initiating Events, Mitigating Systems, Barrier Integrity, Emergency Preparedness, Public Radiation Safety, Occupational Radiation Safety, and Security
4OA1 Performance Indicator Verification
.1 Unplanned Scrams per 7000 Critical Hours (IE01)
a. Inspection Scope
The inspectors reviewed licensee event reports (LERs) for the period of January 1, 2015, through December 31, 2015, to determine the number of scrams that occurred.
The inspectors compared the number of scrams reported in these LERs to the number reported for the performance indicator. Additionally, the inspectors sampled monthly operating logs to verify the number of critical hours during the period. The inspectors used definitions and guidance contained in Nuclear Energy Institute Document 99-02, Regulatory Assessment Performance Indicator Guideline, Revision 7, to determine the accuracy of the data reported.
These activities constituted verification of the unplanned scrams per 7000 critical hours performance indicator for Units 1 and 2, as defined in Inspection Procedure 71151.
b. Findings
No findings were identified.
.2 Unplanned Power Changes per 7000 Critical Hours (IE03)
a. Inspection Scope
The inspectors reviewed operating logs, corrective action program records, and monthly operating reports for the period of January 1, 2015, through December 31, 2015, to determine the number of unplanned power changes that occurred. The inspectors compared the number of unplanned power changes documented to the number reported for the performance indicator. Additionally, the inspectors sampled monthly operating logs to verify the number of critical hours during the period. The inspectors used definitions and guidance contained in Nuclear Energy Institute Document 99-02, Regulatory Assessment Performance Indicator Guideline, Revision 7, to determine the accuracy of the data reported.
These activities constituted verification of the unplanned power outages per 7000 critical hours performance indicator for Units 1 and 2, as defined in Inspection Procedure 71151.
b. Findings
No findings were identified.
.3 Unplanned Scrams with Complications (IE04)
a. Inspection Scope
The inspectors reviewed the licensees basis for including or excluding in this performance indicator each scram that occurred between January 1, 2015, and December 31, 2015. The inspectors used definitions and guidance contained in Nuclear Energy Institute Document 99-02, Regulatory Assessment Performance Indicator Guideline, Revision 7, to determine the accuracy of the data reported.
These activities constituted verification of the unplanned scrams with complications performance indicator for Units 1 and 2, as defined in Inspection Procedure 71151.
b. Findings
No findings were identified.
4OA2 Problem Identification and Resolution
.1 Routine Review
a. Inspection Scope
Throughout the inspection period, the inspectors performed daily reviews of items entered into the licensees corrective action program. The inspectors verified that licensee personnel were identifying problems at an appropriate threshold and entering these problems into the corrective action program for resolution. The inspectors verified that the licensee developed and implemented corrective actions commensurate with the significance of the problems identified. The inspectors also reviewed the licensees problem identification and resolution activities during the performance of the other inspection activities documented in this report.
b. Findings
No findings were identified.
.2 Annual Follow-up of Selected Issues
a. Inspection Scope
The inspectors selected one issue for an in-depth follow-up:
- On January 12, 2016, the inspectors completed a follow-up review of 480-volt AC switchgear room ventilation design airflow issues.
The inspectors assessed the licensees problem identification threshold, cause analyses, extent of condition reviews, and compensatory actions. The inspectors verified that the licensee appropriately prioritized the planned corrective actions and that these actions were adequate to correct the condition.
These activities constituted completion of one annual follow-up sample as defined in Inspection Procedure 71152.
b. Findings
Introduction.
The inspectors identified a Green, non-cited violation of 10 CFR Part 50, Appendix B, Criterion III, Design Control, for the failure to verify the design adequacy of the safety-related ventilation system for the 480-volt AC switchgear and 125-volt DC inverter rooms. Specifically, the licensee failed to verify sufficient ventilation system airflow to ensure the temperature in rooms housing safety-related electrical equipment remained below 104 degrees Fahrenheit.
Description.
The inspectors performed a review of high temperatures in safety-related rooms with a focus on airflow issues associated with the ventilation system supplying the Units 1 and 2 480-volt AC switchgear and 125-volt DC inverter rooms. The inspectors were concerned with the airflow balance of the rooms and noted that the licensee completed the most recent airflow tests in 2009. The inspectors requested information to determine if the measured airflows from the 2009 test and the current configuration satisfied the requirements of the heating, ventilation, and air conditioning (HVAC) design calculation 92-15, 480V AC Switchgear & 125V DC Inverter Rooms Airflow, Revision 1.
However, the licensee could not validate airflows to the rooms which supported design calculation HVAC 92-15. The licensee concluded that minimum design flow requirements may not be satisfied and additional performance testing was required.
The inspectors reviewed the FSARU and other design documents to conclude that the design function of ventilation system is to maintain the indoor air temperature below 104 degrees Fahrenheit. Specifically, FSARU Section 9.4.9.3.6, states in part, the system design indoor temperature is 104 degrees Fahrenheit for the 125-Vdc switchgear and battery chargers, the 480-V switchgear, and the hot shutdown panel.
In addition, Design Criteria Memorandum DCM S-23C, Miscellaneous Auxiliary Building HVAC Systems, Revision 13, stated:
- The safety-related design functions associated with the 480-V switchgear and 125-Vdc Inverter Rooms Ventilation Systems are to limit the maximum ambient temperature in the 125-Vdc inverter rooms, hot shutdown remote control panel area, and 480-V switchgear rooms.
- Supply/Exhaust Fans E-43 and E-44 are each designed to provide 22,000 cfm of air
- These supply and exhaust fans provide a minimum flow of air to the following service rooms and areas, as described in Design Calculation HVAC 92-15 airflow values of:
o 480-V switchgear rooms o 125-Vdc inverter rooms o Hot shutdown remote control panel area o Cable spreading room
- Balancing checks are considered not necessary because dampers positions will not change. However, to ensure the system performance is within design limits, system flows should be checked every five years.
On August 25, 2015, the licensee conducted performance tests to ensure that the minimum airflow assumptions of calculation HVAC 92-15 were satisfied. The test revealed that the ventilation system airflows for seven of the eight rooms did not meet the HVAC 92-15 design requirements. The most significant reduction in airflow was in the Unit 1 125-volt DC inverter Room 1F, where the ventilation system supplied only 51 percent of the required airflow. Specifically, the ventilation system supplied only 1337 cfm versus a required airflow of 2629 cfm. The inspectors reviewed the test results and noted significant airflow imbalances in several rooms for both units that ranged from 66 percent to 140 percent of design values.
The licensee implemented several corrective actions to ensure the ventilation system provided adequate airflow to maintain room temperatures below 104 degrees Fahrenheit. The corrective actions included, but were not limited to:
- (1) a complete airflow balance of the 480 volt switchgear ventilation system;
- (2) installation of blank-off plates in select rooms to reduce airflow and divert it to rooms lacking adequate airflow;
- (3) installation of clips on each register to maintain positive control of the damper and airflow into each room;
- (4) installation of ventilation duct modifications to correct airflow imbalances; and
- (5) program changes to require periodic airflow testing.
After further inspector questioning regarding the impact of the inadequate airflow in these rooms, the licensee completed an engineering evaluation on March 15, 2016. The licensee analyzed several design basis accident conditions and determined that the impact of the inadequate airflow in these rooms was most severe in the Unit 2 480-volt switchgear Bus G Room 2F. Under worst-case accident conditions, this room could reach a temperature of 109 degrees Fahrenheit, which exceeded the design specification of 104 degrees Fahrenheit. However, the evaluation showed the impact to the electrical equipment in the Bus G room was insignificant and that the equipment would continue to perform its safety functions. The inspectors reviewed the updated engineering evaluation and determined that it was accurate.
Analysis.
The failure to provide design control measures to verify the design adequacy of the Unit 1 and 2 480-volt AC switchgear and 125-volt DC inverter rooms was a performance deficiency. The performance deficiency was more than minor because it was associated with the design control attribute of the Mitigating Systems Cornerstone and adversely affected the cornerstone objective to ensure the availability, reliability, and capability of systems that respond to initiating events to prevent undesirable consequences. Specifically, the reduction in airflow to the rooms impacts the reliability of the safety-related equipment ventilation system to maintain the temperatures in these rooms below design limits for the duration of all accident scenarios. Using NRC Inspection Manual Chapter 0609, Appendix A, Exhibit 2, Mitigating Systems Screening Questions, the inspectors determined the finding was of very low safety significance because
- (1) the finding was not a deficiency affecting the design or qualification of a mitigating system;
- (2) the finding did not represent a loss of system and/or function;
- (3) the finding did not represent an actual loss of function of a single train for greater than its technical specification allowed outage time; and
- (4) the finding does not represent an actual loss of function of one or more non-technical specification trains of equipment designated as high safety-significant in accordance with the licensees maintenance rule program for greater than 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />.
The inspectors determined that this finding did not have a cross-cutting aspect because the most significant contributor of this finding occurred more than three years ago, and is therefore, not representative of current licensee performance.
Enforcement.
Title 10 CFR Part 50, Appendix B, Criterion III, Design Control, requires, in part, that design control measures shall provide for verifying or checking the adequacy of design, such as by the performance of design reviews, by the use of alternate or simplified calculational methods, or by the performance of a suitable testing program.
The Updated Final Safety Analysis Report, Revision 13, Sections 9.4.4.1.6 and 9.4.9.3.6, 125-Vdc and 480-V Switchgear Area Ventilation System Safety Function Requirements, established that the design of the safety-related ventilation system, to which 10 CFR 50, Appendix B applies, was to ensure that temperatures in safety-related rooms do not exceed the 104 degrees Fahrenheit. Contrary to above, prior to March 15, 2016, the licensee failed to implement design control measures for verifying or checking the adequacy of design, such as by the performance of design reviews, by the use of alternative or simplified calculational methods, or by the performance of a suitable testing program. Specifically, the licensee failed to provide measures to check or verify the design of the safety-related ventilation system to ensure the 480-volt AC switchgear and 125-volt DC inverter room temperatures remain below 104 degrees Fahrenheit, as specified in Updated Final Safety Analysis Report, Revision 13, Sections 9.4.4.1.6 and 9.4.9.3.6. This violation is being treated as a non-cited violation consistent with Section 2.3.2 of the NRC Enforcement Policy. The violation was entered into the licensees corrective action program as Notification 50840266. (NCV 05000275/2016001-01;05000323/2016001-01, Failure to Verify Adequate Design Airflow for 480 volt AC Switchgear and 125 volt DC Inverter Rooms)
4OA3 Follow-up of Events and Notices of Enforcement Discretion
Notification of Unusual Event - Security Condition that does not Involve Hostile Action On January 14, 2016, at approximately 2:05 p.m. local time, a security condition was initiated at the Diablo Canyon Power Plant due to an unauthorized person on the licensees property within the owner controlled area. The inspectors were on site at the time and were immediately notified about the security condition. At 2:43 p.m., the licensee declared an Unusual Event (EN 51655) due to a security condition that did not involve a hostile action. At 3:20 p.m., the local law enforcement agency apprehended the unauthorized person and removed the individual from the owner controlled area.
The licensee exited the Unusual Event at 4:02 p.m. There were no impacts to the safe operation of the plant from this security event. Both reactor units remained at full power throughout the event.
On February 23, 2016, the licensee retracted the Unusual Event declaration after further evaluation determined that the declaration was not required. The event did not constitute a threat or compromise to site security, did not involve a threat or risk to site personnel, did not represent a potential degradation to the level of safety of the plant, and did not affect the health and safety of the public.
a. Inspection Scope
The inspectors reviewed the below listed events for plant status and mitigating actions to confirm that the licensee properly classified the event in accordance with emergency action level procedures, and made timely notifications to the NRC, and state and local government, as required.
- January 14, 2016, Units 1 and 2, Notification of Unusual Event made for security-related event Documents reviewed by the inspectors are listed in the attachment.
b. Findings
No findings were identified.
These activities constituted completion of one event follow-up sample, as defined in Inspection Procedure 71153.
4OA6 Meetings, Including Exit
Exit Meeting Summary
On March 21, 2016, the inspector discussed the results of the in-office inspection of emergency preparedness plan changes with Mr. Doug Evans, Director, Security and Emergency Services, and other members of the licensee staff. The licensee acknowledged the issues presented.
The inspector asked the licensee whether any materials examined during the inspection should be considered proprietary. No proprietary information was identified.
On April 7, 2016, the resident inspectors presented the inspection results to Mr. E. Halpin, Senior Vice-President and Chief Nuclear Officer, and other members of the licensee staff. The licensee acknowledged the issues presented. The licensee confirmed that any proprietary information reviewed by the inspectors had been returned or destroyed.
SUPPLEMENTAL INFORMATION
KEY POINTS OF CONTACT
Licensee Personnel
- T. Baldwin, Director, Nuclear Site Services
- D. Evans, Director, Security & Emergency Services
- P. Gerfen, Senior Director Plant Manager
- M. Ginn, Manager, Emergency Planning
- E. Halpin, Sr. Vice President, Chief Nuclear Officer Generation
- H. Hamzehee, Manager, Regulatory Services
- A. Heffner, NRC Interface, Regulatory Services
- J. Hinds, Director, Quality Verification
- L. Hopson, Director Maintenance Services
- T. Irving, Manager, Radiation Protection
- K. Johnston, Director of Operations
- J. MacIntyre, Director of Equipment Reliability
- M. McCoy, NRC Interface, Regulatory Services
- J. Morris, Senior Advising Engineer
- C. Murry, Director Nuclear Work Management
- J. Nimick, Senior Director Nuclear Services
- A. Peck, Director, Nuclear Engineering
- A. Warwick, Supervisor, Emergency Planning
- J. Welsch, Site Vice President
LIST OF ITEMS OPENED, CLOSED, AND DISCUSSED
Opened and Closed
- 05000275/2016001-01 Failure to Verify Adequate Design Airflow for 480 volt AC NCV
- 05000323/2016001-01 Switchgear and 125 volt DC Inverter Rooms (Section 4OA2.2)