NS OPERATING EXPERIENCE WEEKLY SUMMARY 93-5
January 29 - February 4, 1993
The purpose of the NS Operating Experience (OE) Weekly Summary is to enhance
safety throughout the DOE complex by promoting the feedback of operating experience
and by encouraging the exchange of information among DOE nuclear facilities. The OE
Weekly Summary is distributed for information only. No specific actions or responses
are required solely as a result of this document.
Readers are cautioned that review of the OE Weekly Summary should not be relied
upon as a substitute for a thorough review of the interim and final Occurrence Reports.
The following events were reviewed during the week of January 29 - February 4,
1993.
ITEM PAGE
1. FACILITY OPERATIONS AFFECTED BY OUT-OF-POSITION VALVES 1
2. PUMP BOLTING DEFICIENCIES 2
3. STANDBY AIR COMPRESSOR FAILURES
AT SAVANNAH RIVER K-REACTOR 3
4. WATER HAMMER CAUSES STEAM LEAK
AT SAVANNAH RIVER H-CANYON 4
5. OCONEE REACTOR TRIP AND SUBSEQUENT SWITCH MISPOSITIONING 4
6. CONTAMINATION AND POTENTIAL PERSONNEL EXPOSURE
AT TANK FARM 5
7. LESS THAN ADEQUATE PROCEDURE REVIEW
CAUSES VENTILATION PROBLEM 6
8. EXPLOSION OCCURS IN LABORATORY FURNACE 6
9. FATAL ACCIDENT IN SUPERCOLLIDER TUNNEL 7
10. EMERGENCY DIESEL GENERATOR FAILURE CAUSED BY PAINTING 8
11. SUBSTANDARD BREAKERS IDENTIFIED AT Y-12 8
12. BATTERY PREVENTIVE MAINTENANCE (PM) 9
ADDITIONAL INFORMATION RELATED TO FOLLOWUP ACTIVITIES
1. FAILURE OF VICTAULIC CAP DURING PRESSURE TEST 10
1. FACILITY OPERATIONS AFFECTED BY OUT-OF-POSITION VALVES
NS reviewed three occurrences this week in which out-of-position valves affected
facility operations. On February 1, 1993, personnel evacuated a building at the
Pantex Plant when an out-of-position valve created the danger that a fire suppression
deluge could have been inadvertently activated. Construction personnel were
releasing air pressure after testing a new air compressor system. However, a valve
thought to be closed was open, allowing plant system air to be released along with
air from the construction air system. The resulting low pressure into the plant air
system required personnel to block the fire suppression deluge system, and the
affected building was evacuated due to Limiting Conditions of Operation (LCO)
requirements. Facility personnel have not been able to determine when the valve was
opened. Facility personnel blocked closed the subject valve, along with six other
valves that if opened could affect plant operations (ORPS Report
ALO-AO-MHSM-PANTEX-1993-0007).
On January 31, 1993, a sample pump seal at the Savannah River Defense Waste
Processing Facility was damaged when it was operated for several minutes without
seal water flow. The seal water isolation valve for that type of seal was normally left
open, but facility personnel closed the valves after experiencing problems with
excessive leakage. However, procedures were not updated to include a requirement
to open the seal water isolation valve before starting the pump. As a result,
operators started the pump and ran it for several minutes without seal water flow,
damaging the seal. Facility personnel have identified and corrected all affected
procedures (ORPS Report SR--WSRC-WVIT-1993-0002).
On January 28, 1993, a uranium enrichment production cell at the Portsmouth
Gaseous Diffusion Plant automatically shut down when operators inadvertently
activated a compressor motor oil pressure sensor. Operators closed a lube oil supply
valve to the compressor motor in order to replace a leaking oiler. The lube oil lines
for some stages contain oil pressure sensors, while others do not. Closing this valve
while the motor is running is normal practice for stages without oil pressure sensors,
since the oiler can be replaced in about one minute and motor bearing heatup is not
significant. However, the oil line for this stage contained a pressure sensor, which
sensed the low oil pressure condition and activated the motor trip circuit, shutting
down the motor and the associated cell. Had the operators verified that this stage
contained an oil pressure sensor, they would have performed a planned cell shutdown
to replace the oiler (ORPS Report ORO--MMES-PORTCASOPS-1993-0003).
In each of these occurrences, correct valve positions were not verified by positive
means. These events underscore the importance of using positive means, including
independent verification, to verify the position of all valves that could affect the
performance of a test or maintenance activity. Even those valves not normally
operated and expected to be in a normal position should be verified if their position
could adversely affect plant operation or personnel safety.
The Savannah River event also illustrates the need for facility personnel to ensure that
they adequately control abnormal valve alignments including documentation of
restoration to normal alignment. For safety-related applications, this should include
independent verification of the restoration. Also, the Pantex occurrence emphasizes
the importance of communications between construction and operations personnel
when operating equipment that provides boundaries between construction and plant
activities.
2. PUMP BOLTING DEFICIENCIES
On January 29, 1993, personnel at the Advanced Test Reactor (ATR) in Idaho
discovered that the M-6 coolant pump in the 1C-W experiment loop was mounted
with only two bolts, instead of the required four bolts. Four horizontally mounted
coolant pumps pump water through the 1C-W loop, which is one of nine ATR
experiment loops. Facility personnel inspected the other pumps in the loop and
identified another mounted with only three bolts.
Workers, using a recently updated procedure, were performing maintenance on one
of the affected pumps when they discovered the deficiency. Previous revisions of the
pump replacement procedure included multiple actions within procedure steps. In the
latest revision of the procedure, multiple action steps were divided making it clearer
and easier for the craft personnel to use. Workers stopped the maintenance when
they were unable to perform the step requiring that four bolts be inserted because of
an alignment problem. The 1C-W M-6 pump had been repaired in May 1992, and
facility personnel have not been able to determine how long the condition existed.
Proper bolting of the coolant pumps is a concern because catastrophic failure of the
pumps or loop piping could cause the Experiment Loop to void, which adds positive
reactivity to the ATR core. Engineering personnel have performed analysis indicating
that the bolting deficiency would not have increased the probability or the
consequences of any previously analyzed accidents and therefore did not result in an
Unreviewed Safety Question (USQ).
In this event, use of detailed procedures and good maintenance practices by craft
personnel led to the discovery of a condition that had gone undetected. This event
illustrates the benefits of using detailed procedures and underscores the need for craft
personnel to inform facility management when deficiencies are noted. This is
especially important because craft personnel may not be aware of facility safety
analysis and design basis requirements, and should not be expected to make
decisions as to the adequacy of deficiencies. To address these concerns, ATR
personnel are discussing this issue with all craft personnel and are continuing to
upgrade maintenance procedures (ORPS Report ID--EGG-ATR-1993-0004).
3. STANDBY AIR COMPRESSOR FAILURES AT SAVANNAH RIVER K-REACTOR
On January 31, 1993, at the Savannah River Site K-Reactor, Central Control Room
operators received the 'Standby Air Low Pressure' annunciator. An operator,
investigating the condition, found that the A compressor coupling had failed and the
redundant B compressor had started. The operator then discovered that a solenoid
valve was stuck open on the B compressor, preventing it from maintaining system
pressure. The operator tapped on the solenoid valve causing it to close and restore
pressure to normal. The operator then stopped the A compressor motor. System
pressure did not decrease sufficiently to cause any dampers in the confinement
system to change position (ORPS Report SR--WSRC-REACK-1993-0017).
This pair of low capacity air compressors supply control air to dampers in the facility
confinement system. They are included in the facility preventive maintenance and
surveillance programs. The facility operators increased the monitoring frequency on
the B compressor as a compensatory action during this degraded condition and
initiated work requests to have both compressors repaired.
Establishing compensatory action on equipment in a degraded condition is a good
practice. Preventive maintenance and surveillance programs do not guarantee that
equipment will always function as required nor do redundant components always
protect against single failures. Predictive maintenance tracking systems can be used
to identify the frequency of failure of components and allow fine tuning of preventive
maintenance schedules and replacement part inventories.
4. WATER HAMMER CAUSES STEAM LEAK AT SAVANNAH RIVER H-CANYON
On January 31, 1993, personnel at the Savannah River H-Canyon facility discovered
a steam leak in the branch header that supplies main steam to process vessels and
building heating. While placing the system into service, operations personnel heard
a load noise and identified a 14-inch steam isolation valve gasket leaking steam.
Facility personnel immediately initiated an emergency shutdown of the system (ORPS
Report SR--WSRC-HCAN-1993-0012). They conducted a walkdown of the steam system
and reported that this event caused no personnel injury or process disturbances. (All
processes had been shut down for the steam system outage.)
Facility personnel report that the leak occurred because of a water hammer that
began when the system was valved into service. They suspect that the system was
brought on-line too fast, and proper pre-heat of the piping was not provided.
Introduction of hot water or steam into colder piping can result in water hammer,
piping deflection and hanger damage. The procedure used for system start-up did not
provide specific time intervals for warming the system before introducing steam.
Facility personnel are now committed to revise the system start-up procedure to
provide these intervals.
This event emphasizes the importance of ensuring system temperature and
equilibrium pressure when valving systems into service. Water hammer and thermal
stresses in piping systems has been the subject of numerous commercial nuclear
industry events. Additional information concerning this subject can be found in NRC
Information Notices IN 91-38 "Thermal Stratification in Feedwater System Piping";
IN 88-80 "Unexpected Piping Movement Attributed to Thermal Stratification"; IN 89-
90 "Potential for Water Hammer, Thermal Stratification, and Steam Binding in HPCI
Systems"; NRC Bulletin NRCB 88-08 "Thermal Stresses in Piping Connected to
Reactor Coolant Systems"; NRCB 88-11 "Pressurizer Surge Line Thermal
Stratification"; and the Institute of Nuclear Power Operations (INPO) SER 25-87
"Pressurizer Surge Line Thermal Cycling."
5. OCONEE REACTOR TRIP AND SUBSEQUENT SWITCH MISPOSITIONING
On January 26, 1993, a technician at the Oconee Unit 3 nuclear power plant caused
two fuses to blow in a circuit supplying the main generator electrical output signal to
the plant's Integrated Control System (ICS). The ICS processes steam flow,
feedwater flow, feedwater pump discharge pressure, generator load, average reactant
coolant temperature, and other parameter signals to automatically control steady
state and transient plant load demands. Because of the blow fuses, the indicated
main generator electrical output decreased below the demand value on the ICS. The
ICS then opened the main turbine valves further in an attempt to return the generator
electrical output to the ICS demand value. This increased steam flow to the main
turbine and caused the main feedwater pump discharge pressure to decrease. The
main turbine then tripped because of the low feedwater discharge pressure and the
Reactor Protection System (RPS) automatically tripped the reactor as a result of the
turbine trip. The plant responded normally after this full power reactor trip with the
Emergency Feedwater System (EFW) actuating as expected (NRC EN 24947).
Plant investigators believe the technician incorrectly positioned the selector switch
on the multi-meter he was using to troubleshoot the equipment, causing the fuses to
blow. Plant personnel have not finalized all corrective actions. Potential corrective
actions include, changing the color of the indicating lights to make them more
noticeable, evaluating middle-of-shift operator relief practices, determining if the use
of check offs in AOPs should be mandatory, and verifying the adequacy of the
training for technicians who use multi-meters.
About two hours after the reactor trip, a second problem occurred. The operators
restarted the Main Feedwater (MFW) System and then shutdown the EFW system in
accordance with the Abnormal Operating Procedure (AOP) for Loss of MFW. The
licensed operator who performed the AOP, did not correctly position two EFW system
control valve switches in the "manual" versus "automatic" position as required by the
AOP and the plant technical specifications. The operators sometimes use a check
mark to note the steps accomplished in an AOP. The use of AOP check offs is
considered optional and this operator did not use it. The status of these valves is
indicated by two white lights, one labeled "Manual" the other "Automatic." The EFW
system was incapable of automatically providing EFW flow to the SGs when these
switches were in manual. This operator was relieved by another operator later during
the shift (not a normal shift turnover). These two operators did not adequately review
the control boards and the mispositioned switches were not discovered. Operators
discovered the mispositioned switches during a control board walk-down for formal
shift turnover, about five and one-half hours later.
This event demonstrates how casual operating practices (optional use of check offs,
informal shift relief) can result in the failure to meet operating requirements. Facilities
can prevent the occurrence of similar events by maintaining compliance with the
requirements of Conduct of Operations manuals and other facility procedures.
6. CONTAMINATION AND POTENTIAL PERSONNEL EXPOSURE AT TANK FARM
On January 21, 1993, at the 241-SY Tank Farm at Hanford, operators found
indication of a leak of contaminated liquid from a waste storage tank. Plant personnel
estimated that about 8 oz. of contaminated liquid had leaked onto the snow and soil.
The operators had been preparing to move an overpack (a large pipe sealed at both
ends) containing an air lance when they discovered the leak. Three air lances had
been removed from Tank TK-101-SY and stored at this location in overpacks. Tank
TK-101-SY is a one-million-gallon tank that is at the top of the tank watch list for the
Hanford Site. Operators had used the air lances in the past to mix the waste stored
in the tank. The highest radiation reading from the leaking overpack was 80 mR/hr.
The spill was cleaned up, and the contaminated material was properly disposed of
(ORPS Report RL--WHC-TANKFARM-1993-0010).
The air lances are no longer in use. Investigators determined that after placing the
air lance into its receiver, operators covered the four inch drain in the over pack with
plastic sheeting and tape. During the subsequent inclement weather, snow and ice
accumulated on the air lance; when the ice melted, it carried contamination into the
overpack. The plastic sheeting then failed, and the contaminated liquid leaked to the
soil. In retrospect, site engineers indicated, a blank flange would have been a better
choice for sealing the four-inch opening.
Later the same day, at the same Hanford location, four workers in a "greenhouse,"
a temporary containment structure, noted a strong ammonia odor as they attempted
to install a drain line on an overpack assembly for an air lance. All were wearing
respiratory protection masks. They noted the odor when they removed a one-inch
pipe plug. One worker left the area, complaining of burning eyes, sore throat, and
a headache. After examination, he was returned to the work site. Upon his return,
they all switched to supplied breathing air respirators and finished the installation.
The next day industrial hygiene personnel checked the work site and found air-borne
contamination in the air lance receivers. Health Physics staff were still working to
establish the levels of radiation exposure experienced by the four workers.
This investigation is continuing, but site personnel have determined that the flushing
procedure used to decontaminate the overpacks and air lances was inadequate. Had
the overpacks and air lances been treated as potential mixed waste, the incident
could have been avoided. Staff have added a visual inspection and radiation survey
to the standard flush procedure to ensure that no "crud" remains on equipment that
has been inside a high level waste tank.
Facilities dealing with high level waste should make sure that the job planning process
includes every possible safety precaution to avoid contamination or personnel
exposure. Equipment that has been used inside a tank holding high-level wastes
should be treated as radiologically and chemically unsafe until properly surveyed by
trained personnel.
7. LESS THAN ADEQUATE PROCEDURE REVIEW CAUSES VENTILATION PROBLEM
On January 25, 1993, at Rocky Flats Building 561, an operator caused the Process
Air Programmer (PAP) to cycle while performing a post maintenance test (PMT) on
a fan in the ventilation system. The PMT required the standby fan to be energized,
but the operator did not identify the correct HAND-OFF-AUTO fan switch position.
Cycling the PAP shut off the ventilation to the building, but the exhaust fan for
affected gloveboxes remained in operation. No plutonium operations were underway
at the time of this occurrence. Facility personnel verified that the PAP cycled in
proper sequence and returned the ventilation system to normal (ORPS Report RFO--EGGR-
ANALYTOPS-1993-0007).
The inadequacy of the procedure was identified in a procedure change notice in
October 1991. The PMT has been performed successfully during the interim period
by using experienced operators knowledgeable of the procedure problem. After the
engineering review process, a Procedure Revision Request (PRR) was issued in June
1992. The PRR is currently waiting approval from the Validation and Verification
group but higher priority work has slowed the process.
In this event, 15 months had elapsed between identification of a problem and
issuance of a notification report. Facility personnel need to address procedure
deficiencies with formal changes rather than relying on operator experience to work
around the deficiencies. An important safety issue, such as proper glovebox or
building ventilation, should receive prompt attention.
8. EXPLOSION OCCURS IN LABORATORY FURNACE
On January 29, 1993, a worker at the Oak Ridge Analytical Chemistry Laboratory
discovered a furnace in Building 4500-S damaged by an apparent explosive chemical
reaction. No personnel were injured as a result of the explosion and the damage was
confined to the furnace. Health Physics personnel surveyed the furnace and found
no contamination (ORPS Report ORO--MMES- X10ANLCHEM-1993-0002). The damaged furnace
is the size of a small microwave oven and is located under a laboratory hood.
Personnel use the furnace to oxidize or "ash" the samples.
Prior to the event, laboratory personnel had placed four beakers in the furnace, each
containing approximately 10 grams of residue. This residue was particlate material
collected from the off-gas stack. Environmental personnel used stainless steel probes
in the stack to collect the particulate samples before sending the samples to the
laboratory for radionuclide analysis. They used a stack probe wash procedure to
collect the residue from the probe in 250 ml aliquots. The sample was then taken to
the laboratory and heated to dryness in the furnace before conducting the
radionuclide analysis. Environmental personnel had discussed the probe washing
procedure with the laboratory group supervisor who suggested that the probes be
cleaned using a 4M nitric acid solution. Environmental personnel decided to use a
commercially available solution named "Radiac Wash" to clean the probes instead of
the previously agreed upon nitric acid, and did not inform the laboratory group leader
of the change. When samples of the probe washing were submitted for further
processing, the material description on the request form stated "WATER & RADIAC
WASH." Laboratory personnel assumed that "Radiac Wash" was the name given to
the probe wash procedure and that the solution was the 4M nitric acid, as had been
previously discussed. During processing, a laboratory technician noticed what
appeared to be organic contaminates in the sample. A decision was made to ash the
sample, a normal procedure when organics are present. The pH of the aliquot was
adjusted using nitric acid and placed into the furnace. The furnace heats the sample
100 degrees Centigrade every 100 minutes until a maximum temperature of 500
degrees is attained. The temperature of the oven was at 200 degrees when the
violent reaction occurred. After the event, laboratory personnel determined that
"Radiac Wash" contained several organic constituents, some of which form explosive
compounds in the presence of nitric acid (e.g., ethylene oxide).
This event underscores the importance of having properly qualified personnel conduct
a hazards evaluation when using new chemicals. The Radiac Wash had not been
analyzed for possible volatile reactions with other chemicals used in the process. An
effective hazards analysis and chemical control program would have required the
analysis of all chemicals and their applications prior to use and could have assisted
in preventing this event.
9. FATAL ACCIDENT IN SUPERCOLLIDER TUNNEL
On January 29, 1993, in the Super-Conducting Supercollider tunnel, a 6000 lb.
segment of concrete tunnel liner fell, killing a construction worker at the N-15
construction site. Construction management suspended all operations until the cause
of the accident is determined (Ref. ORPS Report HQ--URA-SSCL-1993-0001).
The concrete segment is about 5 feet wide by 8 feet long and 9 inches thick and is
one of four segments used to line each 8-foot section of the 2.7-mile tunnel section
presently under construction. Construction workers positioned the segment, using
hydraulic jacking equipment, and then installed hydraulic supports to hold it in place.
It is believed that one of these hydraulic supports retracted, allowing the segment to
fall. DOE is conducting an investigation of the accident, and Parsons-
Brinkeroff/Morrison-Knudsen, the architect/engineer/construction firm managing the
tunnel construction, is performing its own investigation in parallel. A followup report
will be included in the weekly summary as information becomes available.
10. EMERGENCY DIESEL GENERATOR FAILURE CAUSED BY PAINTING
On January 21, 1993, personnel at the South Texas Project commercial nuclear
power plant informed the NRC that one of their emergency diesel generators (EDGs)
had been inadvertently rendered inoperable when it was painted. During a
subsequent surveillance test, the EDG failed to start.
Personnel painted the EDG as part of an upgrade to plant appearance and
housekeeping. This was the first diesel to be painted. The plant decided to paint the
diesel without taking it out of service (OOS) to avoid operating penalties if the diesel
was OOS for more than 72 hours. This decision permitted deleting the
post-maintenance test of the diesel because it had not been taken OOS. Paint
dripped into the metering rod guide holes in the "jerk pumps" (impulse injection pump)
and caused the lockup. Plant personnel removed the paint from the rod guide holes,
verified free movement of the metering rods, and successfully started the diesel (NRC
EN 24914).
The Institute of Nuclear Power Operations (INPO) reported paint binding problems at
three commercial nuclear power plants - McGuire 1, Byron 1, and Palo Verde 3 (INPO
Safety Evaluation Report 16-90). Corrective actions stated in the INPO document
include: (1) a thorough pre-job briefing for the painters, (2) operational tests to verify
equipment reliability after painting, and, (3) restrictions on redundant components so
that operational testing is completed on one redundant component prior to the next
one being painted. This INPO SER was available at South Texas but its
recommendations were not followed.
NRC Information Notice 90-80, Sand Intrusion Resulting in Two Diesel Generators
Becoming Inoperable, dated December 21, 1990, discusses a similar problem. This
notice also describes a case where personnel cleaned the DG intercoolers and treated
them with a corrosion-preventive agent. The intercoolers had been removed from the
diesel engine and prepared for sandblasting by bolting plywood covers over the shell
side and sealing the wood with tape. The covering did not seal adequately and
aluminum oxide entered the shell side of the intercoolers. During subsequent DG
operation, sand was deposited between the piston rings and cylinder liners, causing
heavy scoring.
Awareness of the vulnerability of diesels to ingestion of foreign material can help
avoid unnecessary DG down time. Combustion air intakes must be protected to
prevent the entry of debris. Externally exposed moving parts must be protected from
paint, cleaning solutions, etc. to maintain operability. Strict cleanliness practices and
post-maintenance inspections must be enforced to maintain equipment reliability.
11. SUBSTANDARD BREAKERS IDENTIFIED AT Y-12
On January 27 and 28, 1993, facility personnel at the Oak Ridge Y-12 Site identified
two General Electric breakers as suspect equipment while performing inventory
activities. Upon close inspection, warehouse personnel discovered various non-
conforming conditions including missing factory seals, RTV used to plug ports in the
casing, grind marks on the casing, and inadequate shipping containers. These
breakers were not consistent with the shipping and material quality standards
specified by site personnel. The suspect breakers are 120-volt, 3 phase with serial
number TQD-32150 and manufactured in Brazil (ORPS Reports ORO--MKFO-Y12CENTENG-
1993-0004 and ORO--MKFO- Y12CENTENG-1993-0005).
This event demonstrates the importance of implementing a program to inspect
equipment upon receipt from the vendor. Quality Assurance programs and
procedures are effective in identifying suspect materials. Facilities may want to notify
their Quality Assurance department of this potential problem.
Substandard, counterfeit, and other suspect parts used in nuclear applications is a
concern for both Government contractors and the commercial nuclear industry. The
use of suspect materials in critical applications poses a threat to DOE facility
operation and nuclear safety and may present plant workers, the public and the
environment with increased risk. The Inspector General issued a report in September
1990 concerning the Department's Quality Assurance processes relative to this issue.
As a result of this report, the Program Secretarial Officers initiated a program to
identify suspect parts and initiate corrective actions. Additional information
concerning programs that the Nuclear Regulatory Commission consider to be effective
in providing the capability to detect counterfeit or fraudulently marked products and
assure the quality of procured products may be found in NRC Generic Letter 89-02
"Actions to Improve the Detection of Counterfeit and Fraudulently Marketed
Products." This document lists numerous NRC Bulletins and Information Notices
concerning nonconforming materials and equipment and instances of inadequate
dedication of equipment for safety-related applications.
12. BATTERY PREVENTIVE MAINTENANCE (PM)
On October 7, 1992, the NRC issued a supplement to Information Notice 91-64, Site
Area Emergency Resulting from a Loss of Non-Class 1E Uninterruptible Power
Supplies. Information Notice 91-64 was originally issued in response to the August
13, 1991, event at Nine Mile Point Unit 2 nuclear power plant. During that event,
a voltage disturbance on the electrical distribution buses, the facility lost power from
each of five Non-Class 1E Uninterruptible Power Supplies (UPS). The NRC
supplement provided additional information on replacement intervals for control logic
back-up power battery packs associated with Exide Electronics, Incorporated (Exide)
75 KVA UPS model No. 575-60T3-120/208.
The Exide UPS units have internal continuously charged back-up batteries to prevent
a loss of control logic power. Exide's UPS control logic circuitry receives, processes,
generates, and sends electrical signals essential for proper UPS operation. However,
at Nine Mile Point, the back-up power battery packs were apparently past their useful
life and were completely discharged. The loss of power from the UPSs caused the
loss of a number of critical instrumentation and control systems at the plant.
Exide used Gates Energy Products (Gates) rechargeable batteries for its UPS control
logic batteries. The NRC investigation of the event determined that functional battery
packs acting alone would support the amperage consumption necessary for the UPS
control logic to operate for at least 10 minutes. The Gates performance data sheets
show that battery life expectancy is a function of float voltage and temperature with
charge and discharge cycle life being a function of the depth of discharge.
The Gates data also show that greater float voltage or higher operating temperatures
decrease battery life. For example, a battery could last slightly longer than five years
with an operating temperature of 30 ¯C and a float voltage of 2.3 volts DC (vdc).
If the operating temperature is increased to 40 ¯C with a float voltage value of 2.3
vdc, the battery life expectancy is about three years. If the float voltage is increased
to 2.4 vdc, the life expectancy is about two years. Further, if the operating
temperature is increased to 50 ¯C and the float voltage is 2.4 vdc, the battery life
expectancy decreases to about one year. Therefore, high float voltage combined with
excessively high operating temperature substantially decrease battery life.
At Nine Mile Point, the UPS back-up internal battery packs were completely
discharged, and the utility had not performed adequate PM on the battery packs
commensurate with the actual in-service conditions that could adversely affect
battery life.
The lessons learned at Nine Mile Point are applicable to a number of DOE facilities.
Installations with UPSs that contain backup batteries should assure the batteries
receive periodic PM and are operated within the manufacturer's life expectancy
temperature and float voltage requirements.
ADDITIONAL INFORMATION RELATED TO FOLLOWUP ACTIVITIES
Correction:
In OE Weekly Summary 92-36, NS described a lithium fire at the Lawrence Berkeley
Laboratory waste handling facility. The event description stated that lithium is a strong
oxidizer and reacts with water to form hydrogen. In fact, lithium is incompatible with
strong oxidizers.
1. FAILURE OF VICTAULIC CAP DURING PRESSURE TEST
In OE Weekly Summary 93-1, NS reported an event in which a Victaulic cap failed
during an air pressure test at the Morgantown Energy Technology Center (METC) in
West Virginia, causing minor damage to the facility. Workers were using the
Victaulic cap to establish a pressure boundary at the end of an 8 main fire header.
Not relying completely on the clamping bolts, facility personnel had wedged a 4 X4
post against the cap to help prevent it from blowing off. While the line was
pressurized with 120 psig air, the post slipped off and the cap loosened and blew off.
Mud, stone and water were blown onto the side of a building, breaking the outer
panes of two 30 X36 windows (ORPS Report HQ--GOME-METC-1993-0002).
In OE Weekly Summary 93-1, NS mentioned lessons learned from this event
concerning work package review and proper restraint of temporary devices.
However, personnel at other facilities have provided feedback to NS pointing out
additional lessons to be learned from this event.
They point out that this event illustrates that pressure tests should be conducted with
water, and air tests should only be performed where special circumstances preclude
the use of water. The use of water minimizes the amount of energy that would be
released if the system under test fails, since water is essentially incompressible. Had
a hydrostatic test been performed on this system, instead of the air test, debris would
not have been blown into the building and no damage would have resulted.
However, if special circumstances dictate that a system be pressure tested with air,
special precautions should be taken to ensure that all temporary components are
adequately restrained. Generally, temporary piping components must meet the same
design and installation criteria as the permanent system. Commercial piping design
codes also contain general guidance for circumstances in which an air test versus a
hydrostatic test may be used. This event also demonstrates the importance of
keeping non-essential personnel clear of areas where air tests are being conducted.
SAFETY NOTICES UNDER DEVELOPMENT:
Note: The Office of Nuclear Safety encourages input related to the development of Safety
Notices. If you have any questions, comments, or information concerning events or
issues similar to those described below, please contact Mr. Ivon Fergus, Office of
Nuclear Safety (301) 903-6364.
1. NS has identified a number of events related to the loss of annunciators and
other safety-related equipment caused by problems involving 120-VAC/125-VDC
systems at DOE and commercial facilities. NS is reviewing potential generic
problems associated with the adequacy of 120-VAC/125-VDC systems at DOE
facilities.
2. NS evaluated three events associated with the temporary diesel generator at
Rocky Flats Plant, Building 707. The lessons learned from these events,
particularly as they relate to the control of temporary modifications, are being
considered for dissemination in an NS Safety Notice.
3. NS is developing a Safety Notice concerning problems with Uninterruptible
Power Supplies (UPS).
4. NS is considering developing a Safety Notice related to control of work at
electrical substations and switchyards.
5. NS is developing a Safety Notice related to the handling, storage, venting, and
opening of containers and drums that may be pressurized or may contain
flammable vapors. This notice will contain generic information about proper
storage conditions and the material conditions of containers.
6. NS is working with Lawrence Livermore National Laboratory and DOE-SF
personnel to develop a Safety Notice on cracking in ventilation ducting.
7. NS is considering developing a Safety Notice related to Emergency Diesel
Generator (EDG) fuel oil supplies.
8. NS is developing a Safety Notice addressing uses of independent verification for
equipment positioning.
SAFETY NOTICES PREVIOUSLY ISSUED:
Safety Notice No. 91-1, "Criticality Safety Moderator Hazards," September 1991
Safety Notice No. 92-1, "Criticality Safety Hazards Associated With Large Vessels,"
February 1992
Safety Notice No. 92-2, "Radiation Streaming at Hot Cells," August 1992
Safety Notice No. 92-3, "Explosion Hazards of Uranium-Zirconium Alloys," August
1992
Safety Notice No. 92-4, "Facility Logs and Records," September 1992
Safety Notice No. 92-5, "Discharge of Fire Water Into a Critical Mass Lab," October
1992
Safety Notice No. 92-6, "Estimated Critical Positions (ECPs)," November
1992
Copies of NS Safety Notices may be requested from: Nuclear Safety Information Center,
Office of Nuclear Safety, U.S. Department of Energy, Room S161, GTN, Washington, DC
20585