ML20043F641
| ML20043F641 | |
| Person / Time | |
|---|---|
| Issue date: | 02/12/2020 |
| From: | Office of the Chief Human Capital Officer, Woodard Corp |
| To: | |
| Gary Callaway | |
| Shared Package | |
| ML20043F634 | List:
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| References | |
| Download: ML20043F641 (72) | |
Text
Chapter 13 CASE STUDIES:
LESSONS LEARNED AND CONCERNS
"It is necessary for us to learn from others' mistakes. You will not live long enough to make them all yourself."
Admiral Hyman G. Rickover
Learning Objectives This lesson will provide students better understanding of:
- 1. Wide range of failure scenarios involving EDGs
- 2. Significance and safety implications of selected LERs, etc.
- 3. Potential reliability impact of events beyond EDG system boundary: storms, electrical faults, grid events, etc...
- 4. Potential unintended consequences of events around EDG, including maintenance on building /other systems
Learning Objectives (continued)
- 5. Possible shortcomings in licensee operating or maintenance procedures for EDGs, support systems
- 6. Likely effectiveness of licensee corrective actions
- 7. "Aging" issues, other ongoing concerns for EDG systems
EDG Starting Failures Defective Air Start Motors Twenty incorrectly assembled Ingersol-Rand series 89 ASMs Factory technician installed elastomeric O-rings instead of metallic seals on "pick list" Used in EMD, other engines. First few air starts would have been normal, until o-ring abraded Beaver Valley, Clinton, Davis-Besse, Millstone, Surry, Quad Cities got defective ASMs. Would one on an engine affect starting?
10CFR21-0095, 20 October 2008
Figure 13-1 Correct and Incorrect ASM Sub-Assembly EDG Starting Failures (continued)
Malfunctioning Speed Switch Circuits Malfunctioning dc power supply in gauge board panel caused electrical noise in speed switch circuit, making it change state prematurely during start Wolf Creek, San Onofre start failures caused by electrolytic capacitors (Ten more start failures in 7 yrs at other sites)
Their service life is 10-20 years, depending on environment.
Check DC power supplies for control equipment periodically Information Notices 2010-23, 2012-11
EDG Starting Failures Painting Activities and Cleaning Agents Numerous cases impacting engines, generators, pumps, radiation monitors, fire detection/suppression systems, etc Three reactor trips. Summary in ADAMS under ML091600446 Drop of paint on fuel rack prevented EDG start IN 2009-14 Cleaning solvent damaged 16 safety-related switches. IN 93-76 Undiluted muriatic acid was used to clean EDG room floor!
Common cause: Work Control Shortcomings
Controls Related Failures Spurious Shutdown (Design Oversight)
Starting air may be used for critical control functions including pneumatic control logic for non-emergency protective trips.
Several NPPs found to have starting air compressors not on circuits with backup power. If leaks air pressure drop Loss of pressure during EDG run first un-bypassed protective trips normally bypassed in emergency mode. Engine sensors ultimately affected engine trip.
Support system reliability thru long runs(?)
See IN 98-41
Controls Related Failures (continued)
Inadvertent EDG Start Starting very large load (aux feed pump) caused 1E bus V dip to 80% EDG started unnecessarily Load Sequencer Failure
- ESF load sequencer upgraded from electro-pneumatic to solid state microprocessor. Hi magnetic environment failure Improperly Diagnosed Governor Failures Numerous governors reported "defective" actually not Power-type relays used to provide control input to governor had erratic contact resistance. "Control" relays needed...
Controls Related Failures (continued)
Paint Chips in Woodward Governors Supplied by ESI Found by Duke Energy @ McGuire, April 2011 (incl non-EDG)
Woodward paints governors with Foreign Matl Exclusion (FME) plugs in place. ESI removed plugs to install specified fittings Loose paint chips around fittings and on threads Internal governor clearances as small as 0.0005 inch Ref Part 21 Report 2011-11-01. Revealed ESI documented a governor failure from "foreign material" in February 2010
Controls Related Failures (continued)
Defective Governor Drive Couplings Flexible drive coupling between governor, engine gear train failed. (Speed sensing)
Isoprene couplings used instead of Neoprene required for strength and resistance to chemicals present Manufacturer improved ability to identify materials. Six sites with Transamerica Delaval engines had bad parts replaced.
Part 21 Report 2005-35, 16 September 2005. Previous82-075 documented similar failures, original change to Neoprene!
Figure 13-2 Location of Defective Transamerica DeLaval Governor Drive Couplings Controls Related Failures (continued)
Ignored Circuit Breaker Problem Following automatic reactor trip, a non-safety related circuit breaker did not open to isolate a fault, due to lack of control power to trip circuit.
Licensee records verified control power indicating lights on breaker out for 1 year!
Previous IN 1991-78 and IN 2007-34 emphasized importance of control power to safety and non-safety related breakers.
IN 2010-09 and ADAMS info (Accession No. ML100880412)
Controls Related Failures (continued)
Defective Governor DRU IC Chips Four Woodward governors failed (3 in test, 1 in service)
Inability to adjust frequency (engine RPM)
Defective CMOS IC chip in digital reference unit (DRU): Internal corrosion, de-lamination of package DRUs built Nov 2000 - Nov 2005 had potentially defective IC chips by same manufacturer replaced.
FM reported first failure: Part 21 Report 2004-007-01 Subsequent Part 21 Report 2006-01
Controls Related Failures (continued)
Replacement Time-Delay Relays Susceptible to EMI Brunswick replaced Allen Bradley 700RTC-series TDRs during refueling outage. EDGs failed due to erratic relay restarting.
A-B had changed design, from an obsoleted IC chip to a CPLD (Complex Programmable Logic Device). Time delay restarted when other relays on circuit operated (elect noise). CGD issue.
Transient Voltage Suppressors were installed on other relays See Part 21 Report 25 June 2015, IN 2016-01, and ML15149A148
Engine Mechanical Failures Crankcase Explosions (Recap)
Chapter 12: Cooper "KSV" engine crankcase explosions (13)
Licensee owner group and manufacturer eventually identified, corrected multiple causes Problems exacerbated by fast start-load surveillance testing (See related IN 84-15, IN 94-01)
A textbook case for effective engine condition monitoring
Engine Mechanical Failures (continued)
Defective Diesel Cam Roller Bushings FM "OP" fuel pump cam roller bushings shipped to 15 NPPs Leaded brass, instead of specified bronze wear out quickly (one < 55 hours6.365741e-4 days <br />0.0153 hours <br />9.093915e-5 weeks <br />2.09275e-5 months <br />)
Wear shorter pump stroke decreased power output FM implemented inspections, supplier certification of cam hardness 30 July 2001. Prior cam roller bushing suspect.
Part 21 Report 2007-10
Engine Mechanical Failures (continued)
Defective Nordberg Engine Valve Seats Potential for valve seat inserts to 'drop' from cylinder head bore into the cylinder engine damage Root cause: Design error (amount of interference fit for inserts)
Not apparent until failures occurred outside U.S.
Brunswick and McGuire notified, took corrective action Part 21 Report 2006-12
Engine Mechanical Failures (continued)
Engine Damage Caused by Maintenance Routine lube oil analysis found high level of Cr in lube oil. Unit declared inoperative. Inspection found scored cylinders, rings.
(Two days previous, similar damage found in another EDG.)
Investigation found sand (aluminum oxide) in combustion air intake manifold of both engines.
Water side of combustion air intercoolers had been sandblasted to remove scale, without air side protected.
See IN 90-80 This same event occurred 3 years prior!
Engine Mechanical Failures (continued)
Valve Keeper Seals Missing From Rebuilt Cooper Engine Heads South Texas reported lube oil expelled from a cylinder as EDG was "barred" before a surveillance run All 8 keeper seals (4 valves x 2) missing on rebuilt cylinder head.
Oil originated in rocker arms, fed by the keepwarm system...
Purpose of seals was to stop oil from running down valve stems.
ESI improved rebuild docs and all potentially affected parts at NPPs checked for seals. Sites: Cooper, South Texas, Bryon See Part 21 Report of 23 April 2013
Figure 13-3 Location of Missing Cooper "KSV" Engine Valve Keeper Seals Fire Protection Issues Deaths From Inadvertent Discharge of CO2 Fire Protection Systems CO2 extinguishes fire by smothering it (displacing Oxygen)
A CO2 system protecting the engine room may stop the EDG Numerous cases of unintended discharge of CO2 systems.
63 deaths and 89 injuries since 1975 Proactive licensees will take measures to prevent such events.
Some have changed these systems to manual release only See IN 99-05
Fire Protection Issues (continued)
Unintended Discharge of Halon 1301 Fire Suppression Systems Unlike CO2, Halon 1301 (+) gaseous fire suppression systems extinguish fires only, not people Like CO2, they may stop the engine if drawn into air intake IN 2007-23 covered an incident where a Halon 1301 manual release ("pull") station was mistaken for a fire alarm box IN 97-82 reported a Halon system triggered by a camera flash!
Some fire alarm control equipment can be spoofed by RFI...
Fire Protection Issues (continued)
EDG Building Fires Resulting from Improper Roof Repairs After 21 hours2.430556e-4 days <br />0.00583 hours <br />3.472222e-5 weeks <br />7.9905e-6 months <br /> of 24-hour EDG endurance run (surveillance test),
roofing material caught fire at diesel exhaust pipe penetration.
Improper installation of materials during re-roofing: asphalt paper in contact with exhaust sleeve ( 900F)
Any work near EDG requires oversight + inspection! Roof work needs fire watch and extinguishers See IN 2007-17
- IN 2002-27: Firefighting lessons learned at SanOno, Point Beach, Prairie Island... HRR of HV switchgear/cable fires much est. due to arc energy deep seated fires that reflash. Need H20 to ext
Engine Cooling Failures Fouled Heat Exchangers Two tandem EDGs powering a generator tripped out on high jacket water temperature.
Jacket water heat exchangers were fouled, reducing ability of engines to reject heat. Probable failure during emergency run near design load.
Heat exchangers cleaned, maintenance interval reduced IF on-site water is used, heat exchanger fouling / high water temperature can impair cooling...
Engine Cooling Failures (continued)
Water Leaking Into Cylinder During pre-run check after 7 days idle, San Onofre engine roll-over procedure found several pints of water in a cylinder Five years before they had similar engine "save" Had started procedure a decade earlier, after hydraulic lock severely damaged engine (EMD) during start.
Engine "roll" / "bar" before a run is not universal practice but should always be done after extended idle period See IN 91-62
Engine Cooling Failures (continued)
EMD Jacket Water Pump with Incorrect Impeller Orientation EMDs have 2 centrifugal jacket water pumps (1 per bank), both turning in opposite direction from crankshaft. Most EMD EDGs have 2 engines in tandem, Gen in middle, so one LH and one RH.
JWPump for LH engine uses different impeller than one for RH.
Grand Gulf reported pump with wrong impeller Lower output Less engine cooling EDG could fail ESI improved visual aids, licensees checked impellers on pumps in stock/on potentially affected EDGs. What lessons learned?
See Part 21 Report, 30 March 2011
Fuel Oil / Lube Oil Related Failures Leaks Caused by Fatigue Cracking Have occurred in fuel oil, lube oil, water piping Many were fatigue cracks in welded joints, induced by normal engine vibration, over time...
Some involved FM "OP" engines produced when partial-penetration welded joints used in fabrication Problem not unique to OP (200 weld joints). FM has since switched to full penetration welds, ASME Section III, Class 3.
All EDGs have potential for fatigue cracking See IN 98-43.
Fuel Oil / Lube Oil Related Failures (continued)
Cold Fuel Oil Concerns Multiple sites found with fuel specs inadequate to assure proper cold weather performance Pour point, cloud point criteria inappropriate for site temps Most concern: Sites with above-ground fuel tanks/piping without heat tracing powered from safety source Temp cushion of 10°F recommended. Common-mode failure (Surveillance runs may not uncover cold fuel problem. Why?)
See IN 94-19
Fuel Oil / Lube Oil Related Failures (continued)
Cylinder Failures Caused by Improper Fuel Oil Following 110 percent load surveillance tests, engine clattering noted, engine shut down.
Inspection revealed two badly overheated pistons, scored liners, badly worn connecting rod and wrist pin bearings.
All fuel injectors coated with paraffin. Several cylinders not firing, or producing small amount of power. Confirmed by records of extremely low and high exhaust temps(!)
Analysis disclosed non-spec fuel oil. Tanks drained, refilled.
Take-away lessons from this event?
Fuel Oil / Lube Oil Related Failures (continued)
High Pressure Fuel Leak During post-maintenance test run, supervisor noticed fuel spraying from high pressure line for cylinder 1R.
Engine shut down, line replaced. Recurring problem.
Engine manufacturer (Worthington) developed replacement double-wall fuel pipe Fire hazard (1R adjacent to exhaust, right bank turbo!)
Importance of walk-around inspections before-during-after
Fuel Oil / Lube Oil Related Failures (continued)
Lube Oil Incompatibility with Low-S Fuel (One step before ULS)
During pre-op testing of newly installed EDG, wide crankcase pressure fluctuations + other anomalies noted.
Heavy carbon deposits on pistons and rings, scuffing of cylinder walls. (Also found in other EDGs)
Root cause: Fuel oil-lube oil incompatibility. Supplier delivered fuel with 500ppm (0.05%) S, to meet new EPA regs. Prior fuel 3000ppm (0.3%) and lube oil contained additives to neutralize sulfuric acid that would produce. Result: Unreacted additives.
Engines rebuilt, changed to LS-compatible lube oil.
See IN 96-67. This revealed a synthetic oil characteristic
Fuel Oil / Lube Oil Related Failures (continued)
Synthetic oils contain diester additives to improve solubility of oil additives. If oil sump temperature low, water may accumulate in sump (instead of vaporizing). Can cause hydrolysis of diesters.
Resulting acids react with calcium in additive, forming insoluble compounds (soaps) clog filters, degrade diesel performance Next step for fuel oil was in 2010: Ultra-Low Sulfur (ULS) with 15ppm (0.0015%) maximum S required for all non-road uses.
(Some suppliers delivered ULS in 2006, when CA required for all.)
Following ULS Diesel concerns are from IN 2006-22, other sources:
Good place for a break!
Special Concerns for ULS Diesel Fuel (ULSD)
ULSD (max 15ppm Sulfur) can potentially impact diesel engine performance Properties other than S concentration are changed as result of change to ULSD. These may affect diesel engine performance:
Energy Content Processing reduces volumetric energy content at least 1.2%
Fuel consumption increase due to lower energy content Less energy output can reduce instantaneous output rating
ULS Diesel Fuel (continued)
Fuel Particulate Build-up Increases Additives to compensate for lower lubricity can react or become unstable in storage, increasing fuel particulates that may foul or plug filters, fuel injection equipment.
Some licensees report more particulates. (Impact on filters)
Fuel System Seal Leaks Non-nuclear experience with ULSD shows increased incidence of fuel system leaks at elastomeric o-rings.
Linked to reduction in aromatics content (affects seal swelling).
ULS Diesel Fuel (continued)
Compatibility with Lubricating Oil Previously discussed (IN 96-62). ULSD concerns mirror LSD.
Microbial Growth Diesel fuel desulfured by hydrocracking (vs. hydrotreatment) may have more microbial growth, due to increased n-alkanes.
Incompatible Metals Copper and zinc incompatible with ULSD because both are oxidative catalysts that accelerate the formation of sediments, gels, soaps (ASTM D975, Appendix X2.7.2).
ULS Diesel Fuel (continued)
Lubricity Processing required to reduce S to 15 ppm also removes naturally-occurring lubricity agents in the fuel.
Refiners treat ULSD with additives, batch-to-batch, to provide lubricity. Fuel with inadequate lubricity very unlikely.
These potential issues with ULSD are well understood and can be addressed in a straightforward way by licensees.
Biodiesel fuel oil poses more troublesome issues. IN 2009-02
Biodiesel Fuel Concerns In 2008, ASTM approved change to their D975-08a, Standard Specification for Diesel Fuel Oils. Effective in early 2009, No. 2 petrodiesel fuel oil could have up to 5% biodiesel blend without being so labeled Potential issues for EDG engines:
Cleaning Effect B5 has solvent effect, loosens accumulated sediment in fuel storage tanks filter clogging. Will dissolve some paints!
Licensees can clean tanks, upgrade filters, check filters more often before any use of B5. (Assume B5 in fuel unless...)
Biodiesel Fuel (continued)
Water B5 contains suspended water, from manufacturing. Falls out of suspension, forms "dirty water" in fuel tank algae growth.
Licensees can use moisture dispersant and biocide, add fuel-water separator, keep tanks topped off.
Biodegradation B5 biodegradable! Water, heat, oxygen, impurities accelerate degradation. Storage >6 months not recommended vs
Biodiesel Fuel (continued)
Material Incompatibility Brass, bronze, copper, lead, tin, zinc (tanks /fittings) increase oxidation of B5, creating fuel insolubles, gels, salts. Avoid zinc linings, copper pipes-fittings, or brass regulators with B5.
Licensees should verify elastomeric materials compatible with B5 (hoses, gaskets, O-rings).
Temperature Protection Biodiesel fuels have higher cloud points than petro diesel.
(Varies with with biodiesel feedstock)
Combustion / Ventilation Air Engine Exhaust / Room Cooling Exhaust Recirculation to Intakes EDG ratings have max temps for combustion air inlet, engine room ambient. Combustion air must be non-contaminated.
Maximums for intake air depression and exhaust back pressure.
Recirc of combustion exhaust /room cooling exhaust back into air intakes for engine combustion /room cooling is a problem.
One licensee could not take advantage of engine up-rating mod until eliminating up to 15% recirculation of engine exhaust and room ventilation exhaust (back into air intakes).
Site Switchyard and Distribution Concerns Single-Failure and Fire Vulnerability of Electrical Safety Buses NRC inspectors found electrical protection and metering circuit which, if damaged, could electrically lock out redundant safety buses, prevent re-energization from any source Cable fault / watt-hour meter failure would be interpreted by protection system as electrical bus fault on both safety busses.
Relay logic would lock out both.
Violated 10 CFR 50 Appendix A, GDC 17 "I-R-T" criteria. Licensee separated protective circuits, removed meter.
NRC found single-point vulnerabilities at 5 other plants
Site Switchyard and Distribution (continued)
Large Transformer Failures Industry data: Increasing trend in large transformer failures Transformer failures caused 8 declared plant events between Jan 2007 to Feb 2009 (2nd leading reason).
Root cause analyses show these often the result of ineffective transformer maintenance.
Reference only: IEEE Std. C57.140-2006, Guide for Evaluation and Reconditioning of Liquid Immersed Power Transformers See IN 2009-10 and transformer data on next two slides
Transformer Gasses Produced by Overheating or Faults
Transformer Gas-in-Oil Analysis:
--- Table of Recommended Action ---
Site Switchyard and Distribution (continued)
Submerged Electrical Cable Failures NRC began detailed review of underground ac/dc cables in 2006, after moisture-induced failures at several plants. Staff identified 23 LERs for such (1988-2004).
GL 2007-01 issued to gather information on inaccessible or underground power cable failures, for all circuits within scope of Maintenance Rule.
Concern: Licensees not maintaining safety-related power or low voltage cables in their designed and tested environment Actions: Water removal, installation of sump pump, repair of drainage, cable evaluation /testing.
Grid Reliability Concerns LOOP/SBO More Likely in the Summer NUREG-1784 (2003) showed switchyard/grid-related LOOP events occurred mostly in summer. New INEL report, NUREG/CR-6890, confirmed earlier data on seasonal risk trends:
LOOP frequency more than 2X in summer Probability of LOOP after reactor trip also higher All categories of LOOP events (plant, switchyard, grid, weather) more frequent in summer Implications for plant operations. See IN 2006-06
Grid Reliability (continued)
Grid Reliability Has Impact on Plant Risk Largest U.S power outage occurred in NE, 14 August 2003. Nine U.S. NPPs tripped, of which eight lost offsite power (< 7 hrs.)
NPPs designed to cope with LOOP but considered precursors to SBO. Any increase in frequency or duration of LOOPs increases probability of SBO, possible core damage.
Due to grid reliability concerns, NRC issued GL 2006-02: "Grid Reliability and the Impact on Plant Risk and the Operability of Offsite Power." All licensees directed to provide substantial data relative to grid concerns. NRC goals:
Grid Reliability Concerns (continued)
Better communications between NPP operator and the TSO (Transmission System Operator) Re: grid-plant status.
TSO use of analysis tools to determine impact of the loss or unavailability of various transmission system elements.
Communication protocols between NPP's and TSO's Real-time NPP operator knowledge of grid status, esp. whether loss of that NPP will result in LOOP.
Real-time TSO knowledge of NPP's status, especially grid-risk-sensitive maintenance activities.
Determine if more NPP operator training needed
The Ticking Clock: Aging Issues for EDGs Post-TMI Load Creep EDG Design Basis still relevant?
As safety equip modified / replaced / updated, loads change.
Other factors: climate change, ULS fuel, >DesignBasisEvents Also relevant: IN 93-17, TI 2515/176, follow-up document ML093370252all regarding EDG design basis adequacy.
(Ch 11: DBE would load 46% of EDGs above continuous rating)
The Ticking Clock: Aging Issues (continued)
Underground Fuel Tanks All UG steel fuel tanks will eventually leak Just a question of when. Fiberglass tanks = seismic issues...
Coatings + well-maintained cathodic protection will delay the inevitable, but licensees must be vigilant for tank problems.
Effective program of fuel oil analysis and trending is essential.
RG 1.137 Rev 2 (June 2013) requires monthly tank inspection for condensate. Every 10 years: Empty, clean, internally inspect.
Also, Flash Point test of delivered fuel before off-loading, other parameters to be tested within 31 days
The Ticking Clock: Aging Issues (continued)
Replacement Parts Unavailability Impacts all NPP systems, worsened by plant license extensions and "orphan" EDGs. (IEEE 387-1995 addresses EDG aging)
EDG concerns: Legacy engine governors, circuit breakers, relays, parts for engines/accessories/support systems.
Substitution of electrical/mechanical components often means "Commercial Grade Dedication." NRC has expressed concerns about the process: Is evaluation for environmental, seismic, vibration, EMI/RFI being adequately done?
See IN 2014-11
The Ticking Clock: Aging Issues (continued)
Electric Cable Insulation Degradation Premature Failures GL 2007-01 addressed all underground or inaccessible cables within scope of 10 CFR 50.65 (not just those wet).
Licensees to provide history of their cable failures and also describe their cable inspection, testing, monitoring programs.
Issues identified at multiple plants "Widespread" Comprehensive follow-up for multiple plants: IN 2010-26 The next slide depicts an insulation breakdown mechanism called "water-treeing" (wet), "electrical treeing" (dry)
Figure 13-3 "Water-Tree" in Electrical Cable Insulation The Ticking Clock: Aging Issues (continued)
Electric Cable Insulation Degradation (continued)
Industry concern: Cross-linked PE insulated cable (type XLP)
"Hi-Pot" Testing: Dielectric Breakdown / Withstand Voltage ...
Insulation Resistance (NTD), Polarization Index: Definitive?
Ultrasonic Microscopy research paper See NUREG/CR-7000 (BNL-NUREG-90318-2009), "Essential Elements of an Electric Cable Condition Monitoring Program"
The Ticking Clock: Aging Issues (continued)
Station Battery Life: Potential Impact on Surveillance Reqmts Class 1E batteries supplying DC loads are lead-acid, deteriorate over time (lead sulfate build-up on plates). Capacity tapers off to 80% @20 years, where RG 1.129 recommends replacement.
Critical function: Power during station blackout (SBO) for EDG starting-loading, instrumentation, controls, emergency lighting.
NRC concern: Battery surveillance requirements in TS may be non-conservative, due to post-TMI load creep, other factors.
See IN 2013-05
The Ticking Clock: Aging Issues (continued)
EDG Voltage Regulator Failures from accumulated Heat, Vibration
- IN 2007-36 VR failures at Seabrook, Palo Verde, Cooper, involving K1 contactor/relays, or circuit board fatigue cracks.
All Plants: 50 VR failures from various causes, 1997-2007.
Ten of those were due to K1 contactors (used for shutdown and interlocked with field flashing relay via aux contacts).
Part 21 Report of 21 September 2007 by MPR Associates: Solder joints on Basler VRs may fail from vibration fatigue.
Also ADAMS Accession Nos. ML070820085, ML063400561
The Ticking Clock: Aging Issues (continued)
EDG Voltage Regulator Failures from accumulated Heat, Vibration IN 2019-02 Recent failures at Catawba, Wolf Creek, Grand Gulf Catawba previously had same failure. Set up new PM: Replace diodes, SCRs at 18 months.
Wolf Creek VR bridge rectifier diode(s) failed, overstressed PPT, eventually flaming it. (Odors prev noted on Surveillance runs!)
New PM set up to replace involved components periodically.
Grand Gulf mirrored Catawba. Previous failures. PM set up.
Related IN 2010-04 Thermography PM set up to assess VR diodes, bridge rectifiers, transformers, linear reactors, etc.
The Ticking Clock: Aging Issues (continued)
Beyond Design Basis Events: Flooding New information can "age" (obsolete) plant design assumptions.
Fukushima was the classic case for that After Fukushima NRC focused on potential beyond-design-basis events, with emphasis on potential flooding events: tidal surge, river flooding, dam breakage, etc.
Some plants found to have flooding vulnerabilities from events less than design basis, due to infrastructure deterioration.
See IN 2015-01
The Ticking Clock: Aging Issues (continued)
Accumulated Impact of Unnecessary Fast Starts of EDGs Some licensees still routinely performing fast EDG starts.
( f licensee's TS, plus engine governor type and setup)
Unnecessary damage to EDGs, reduced useful life...
Effect of NPP license extensions Licensees should understand new direction of IEEE 387-1995 and RG 1.9 Rev 4 (Re engine stress)
Previous NRC actions: Generic Letters 84-15 and 94-01
The Ticking Clock: Aging Issues (continued)
The Human Factor: The Heavy Loss of Experienced Personnel Increasing loss of experienced personnel due to retirement.
Their departure impacts experience level at licensee facilities, design firms, and within NRC.
Amplified by license extensions + new plants being planned, constructed. Must not impact NPP safety NRC News S-13-004: Speech by NRC Commissioner Magwood at Regulatory Information Conference, 3-2013: "Who Are We?"
Industry EDG Activities: An Overview Owner's Groups for Fairbanks-Morse, EMD, other engines keep abreast of EDG problems through "Alert Lists."
Support organizations include Electric Power Research Institute (EPRI) and the Institute of Nuclear Power Operations (INPO).
Their combined operational and failure data is sent to Owner's Groups via INPO Consolidated Events System (ICES), successor to both the EPRI "NPRDS" and INPO's "EPIX" data bases.
World Association of Nuclear Operators (WANO)
NOTE: ETDE.org (Energy Technology Data Exchange) has ceased operations.
END OF CHAPTER 13