EH-9302 February 1993 Occupational Safety Observer
FEBRUARY 1993
Occupational Safety OBSERVER
Laser safety
Eye Injury Occurs during Laser Alignment
Within the research and development community,
alignment-related accidents account for half of all laser
incidents. Nationwide, 40 percent of all accidents involving
lasers occur in the alignment process. A recent eye injury
incident at Lawrence Berkeley Laboratory (LBL) illustrates both
the dangers of lasers and the steps that can be taken to minimize
risk.
(ORPS Ref. # SAN--LBL-MSD-1992-0001)
What happened
On November 3, 1992, an individual conducting an experiment
at LBL was performing an alignment procedure on a laser. During
the alignment process, the laser was producing both a visible
beam and an invisible infrared beam. The experimenter was in the
process of aligning the visible beam. However, a beam stop for
the infrared beam was not in its proper position. This permitted
the infrared beam to reflect into the experimenter's eyes. The
experimenter incurred retinal damage to his right eye and minor
damage to his left eye.
How could this have been prevented?
Safety guidelines require the use of protective eyewear
while aligning lasers. In this case, however, the experimenter
did not use protective eyewear during the alignment. In
addition, the experimenter did not follow the standard practice
of verifying that all beam stops were in place before beginning
the alignment.
OSHA standards for industry, 29 CFR 1910, do not
specifically address lasers. OSHA recommends adherence to the
American National Standard for the Safe Use of Lasers, ANSI
Z136.1-1986. Part 4.4.5 of this guidance covers alignment
procedures. It points out the "significant ocular hazard" that
may exist during alignment procedures and requires written
procedures for alignment of Class 4 lasers. Part 4.5.6 covers
the use of eye protection devices, and specifically requires
their use when there is potential for exposure.
Corrective actions initiated at LBL in response to the
incident include enhanced safety awareness training for personnel
involved in laser operations; review of safety procedures;
conduct of laboratory laser safety inspection; and acquisition of
improved laser safety goggles.
Lessons learned
This incident also suggests several lessons learned for
other DOE sites.
o The use of appropriate protective eyewear is essential. The
state of the art in eyewear technology has advanced
dramatically in recent years. Comfortable, user-friendly
eyewear is available in a broad range of optical densities,
including those needed for alignment procedures.
Page 2 Occupational Safety OBSERVER
o Experience and familiarity with lasers alone cannot prevent
accidents. In fact, the majority of laser accidents involve
personnel with more than 3 years of experience. No matter
how experienced you are, always be careful around lasers,
and do not deviate from safe practices.
o Management must recognize that training alone does not
ensure continued implementation of safety practices.
Periodic direct observation of operators, including senior
personnel as well as inexperienced staff, by a supervisor or
safety officer is a key practice for ensuring safety.
Suspended Loads
Tank Falls In Rigging Accident
Many things can go wrong during a rigging operation.
Workers in the vicinity of suspended loads must always be aware
of the potential for serious injury should a load fall. It is
always good practice to stay clear of a rigging operation, unless
the work requires otherwise. Those who must work near the
operation should always be aware of what is going on around Ä and
above Ä them. Workers must also ensure that rigging equipment
and techniques are adequate for the job. Failure to do so can
lead to injury or even a fatality, as happened at the Oak Ridge
K-25 site.
(ORPS Ref. # ORO--MMES-K25GENLAN-1992-0094)
The Accident
On the evening of November 14, 1992, a subcontractor was
installing a polyethylene tank onto a new foundation. The tank
weighed nearly 3000 pounds (including over 1000 pounds of
residual water). It was 10 feet in diameter and 12 feet high.
Approximately ten workers were involved in the job. As the tank
was being lifted by a crane truck, one of the two nylon straps
supporting the tank broke. The tank fell and bounced, striking
and fatally injuring one of the workers who was guiding it into
place.
Investigation revealed that the straps used for lifting the
tank contributed to the accident. The failed strap was designed
as a tie down and was tagged, "Not for use for overhead lifting."
Further, although it was rated at 4500 pounds, with a yield
strength of 6000 pounds, the strap had a 6/10-inch flaw that
reduced its strength by 60 percent.
Work practices were also a factor. Workers failed to
inspect the strap, so they were unaware of the flaw. The work
crew did not use tag lines to position the tank, so the fatally
injured worker had to approach the tank to help guide it into
place. There was no pre-job briefing and no review of the
rigging plan and design. The DOE implementation requirements did
not flow down from the prime contractor to the subcontractors.
Several OSHA regulations pertain to this accident.
Regulations require that rigging equipment not be loaded in
excess of its safe working limit (29 CFR 1926.251), that straps
bear tags showing their rated capacity (29 CFR 1926.251), and
Occupational Safety OBSERVER Page 3
that a "competent person" inspect the rigging setup to ensure
that it is safe (29 CFR 1926.550).
Some Safety Guidelines
The basic safety guideline is that if your work assignment
does not absolutely require you to be near rigging activities,
stay completely away from them. Many bystanders have been
killed during rigging operations only because their curiosity
made them get too close.
Never allow yourself to be directly below a suspended load.
This is obviously the most dangerous area during a lift. If you
are inadvertently caught directly beneath a load, quickly but
carefully move away in the direction opposite the direction the
load is moving, if possible. Also be aware of where the load is
moving. If the rigging fails while the load is in motion, the
load may be thrown in that direction. In the K-25 accident, the
fatally injured worker was not directly beneath the load, but was
in the load's line of motion.
In addition to watching the load, keep an eye on the crane
itself. Watch the movement of the boom and the counterweight (on
the tail of the boom or at the rear of the cab) as the crane
rotates, as well as the movement of the crane truck. It's often
difficult to consider the clearances required for these movements
as workers and onlookers move on and around the crane. As a
result, a worker may be crushed between a moving part of the
crane and a stationary object or run over by the crane. Don't
expect the crane operator to know where you are; his or her full
attention should be on the load or on the designated signaler.
It is also important to stay clear of the danger zone
surrounding the suspended load. The danger zone is the area in
which the load or lifting device may fall if any load-bearing
component fails. The shaded area in the illustration below
depicts the danger zone. (This illustration is not drawn to
scale.) Avoid this zone, unless the job requires that you enter
it.
This danger zone would include, for example, the area
surrounding the crane, as there is always the danger of the crane
toppling. Portable equipment is, at best, difficult to
stabilize. A crane can topple when its outrigger stabilizers dig
into soft soil, which is common at construction sites. Also, a
crane can be quite stable when the load extends along the length
of the crane, but can topple when the load is swung to the side.
The danger zone also includes the area in line with the
boom, either in front of or behind the crane. Should the cable
break while lifting a load, the cable will flail about the axis
of the boom Ä sometimes with sufficient force to slice through a
steel girder. (The crane may also topple.)
For large loads, the cable may be several hundred feet long,
as it will run between the blocks on the ends of the boom several
times to obtain sufficient mechanical advantage for lifting. The
cable has a lot of potential energy as it stretches under a load.
If it breaks, the falling load may be the least of the hazards.
Watch Your Step
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Two Workers Injured in Falls
Because we are accustomed to working at moderate heights,
both at work and at home, and because we do so without secondary
restraining devices such as safety belts or harnesses, we often
don't think about the potential for serious injury from falling.
In the following examples, similar attitudes have contributed to
injuries at DOE sites. In particular, these workers each placed
their weight on a surface that could not support it.
Fortunately, neither of the workers involved in these accidents
was seriously injured; but these accidents could easily have been
much more serious, or even fatal.
o A carpenter working inside a cooling tower at the Portsmouth
Gaseous Diffusion Plant stepped onto a small wooden brace
that collapsed. The worker fell about 12 feet and sprained
his shoulder.
o At Oak Ridge, an electrician stepped from the basket of a
cherry picker to the roof of a shed. The roof gave way and
he fell. As he fell, he grabbed for a girder and severely
lacerated his arm.
These examples illustrate a simple rule for working at an
elevated position Ä watch where you step. Several OSHA
regulations in 29 CFR 1910 govern the use of ladders and
scaffolding. These regulations are important and you should be
aware of them. But common sense and an awareness of your
surroundings is also important. Do not place your weight on
something unless you are certain it will support you.
Negligent Homicide Conviction
Loader Accident at Construction Site
Just because we perform a task on a regular basis, we cannot
assume that the task will always be safe. Equipment operators
need to pay attention to detail. They need to verify the
condition and recognize the limitations of the equipment. As
shown by an unfortunate incident at a construction site in
Wisconsin, the operation of any equipment can be hazardous.
On September 1, 1992, a worker was operating a front-end
loader up a steep hill. As the loader was ascending, its tires
lost traction and the loader began to slide back down the hill,
gaining speed. The worker could not stop or control the vehicle.
It rolled for several hundred yards and then plunged into a newly
dug basement and tipped over, crushing the worker and killing him
instantly.
Three factors
The accident investigation revealed three factors that
contributed to the accident. Each factor can be linked to the
relaxed attitude that can surround an activity that most perceive
as being routine.
The first factor was a lack of training: the worker's usual
assignment was to operate a tracked front-end loader. The
Occupational Safety OBSERVER Page 5
accident occurred as he was operating a wheeled front-end loader.
He had not been trained to operate the wheeled loader. While it
is not known exactly what happened, it is possible that an
incorrect assumption was made Ä if a worker could operate a
tracked loader then he could operate a wheeled loader without
specific training. But the controls for the two types of loaders
are different; a tracked vehicle, for example, is steered with
its brakes. Had the worker been trained on the wheeled loader,
he might have been able to better handle it during the emergency
and might have prevented the accident. It is also possible that
the worker was accustomed to the greater traction provided by a
tracked loader, which might have prevented the accident.
The second factor was poor maintenance. The only
functioning brake was on the right rear wheel of the loader Ä and
it was out of alignment. The left rear brake's cylinder was
leaking fluid so badly that the brake was essentially useless.
Again, maintenance might have been postponed out of complacency Ä
no one ever got around to it.
The third factor was poor recordkeeping. In addition to the
problems with the rear brakes, the front brakes had been
disconnected earlier to modify the loader for a special job. The
emergency brake had also been disconnected. Because the nature
of this special job is not known, it is difficult to say whether
those modifications were necessary; however, records of the
modification should have been kept so that workers were aware
that the front brakes did not work and so that the brakes could
be reconnected once the special job was done. Maintenance
records were also insufficient.
Serious consequences
The contractor faced serious repercussions for this
accident. The contractor was convicted of criminal negligent
homicide by the local Wisconsin circuit court. The federal OSHA
investigation is still pending, but will likely lead to a civil
court fine, as OSHA regulations were violated. These regulations
involved the contractor's responsibility to ensure general
workplace safety (29 CFR 1926.20), training (1926.20), and motor
vehicle safety (1926.602).
Chemical Exposure
Workers exposed to sodium hypochlorite during routine transfer operation
Usually incidents occur as a result of a combination of
circumstances. A recent chemical exposure incident at the
Pittsburgh Energy Technology Center (PETC) illustrates how a
series of mishaps can contribute to an incident.
(ORPS Ref. # HQ--GOPE-PETC-1992-0011)
What happened
On December 7, 1992, plant workers and vendor personnel were
attempting to transfer a shipment of liquid ferric chloride. The
transfer operation was prevented by a frozen check valve. When
the transfer operation failed, the vendor disconnected the
transfer hose without bleeding off the built up pressure created
Page 6 Occupational Safety OBSERVER
by the transfer pump. The transfer line contained residual
sodium hypochlorite from a previous delivery which sprayed the
two plant operators when the line was disconnected. The transfer
operation was successfully reattempted and completed
approximately 30 minutes later. Then the two workers directly
exposed and four workers in an adjacent area sought medical
attention for the sodium hypochlorite exposure.
What went wrong
A malfunction and a series of errors led up to this
incident. An error occurred when the vendor failed to flush the
line of a potentially dangerous substance following a prior
delivery. Sodium hypochlorite is an oxidizer found in liquid
laundry bleach, among other common substances. Inhalation can
produce severe bronchial irritation or pulmonary edema, while
skin contact can cause irritation.
The plant workers did not know that there was sodium
hypochlorite in the line, and the vendor had presumably
forgotten. When their transfer failed because of a frozen check
valve at the receiving end of the line, the vendor or plant
personnel (or both) committed an error by failing to bleed the
pressure from the line before disconnecting the fitting. It is
unclear from the information on this incident whether the workers
suffered any immediate symptoms from their exposure. The
transfer was not stopped. Instead of seeking medical attention
the workers completed the transfer.
Applicable OSHA Regulations
OSHA Standard 29 CFR 1910 contains several regulations
covering work with hazardous chemicals. Subpart 119 is the
Process Safety Management Standard containing the requirements
for performing a formal Process Hazards Analysis when working
with hazardous chemicals. Subpart 133 requires the use of
personal protective equipment whenever there is the risk of
worker injury.
In addition to ensuring compliance with the relevant OSHA
regulations, workers at all DOE sites should take any chemical
exposure seriously and seek appropriate medical assistance before
continuing with the task at hand.
Lessons for other DOE sites
Among the many possible lessons learned emerged from this
incident are the following:
o If not adequately controlled, vendors can introduce
unexpected hazards into the DOE workplace. Procurement
agreements should contain adequate safety requirements and
vendors must be held to these requirements. In this case,
the residual sodium hypochlorite should have been removed
before loading the ferric chloride and the operator trained
in safe decoupling.
o The hazards associated with material transfers should be
identified and there should be adequate assurance that the
transfer equipment and operating procedures adequately
Occupational Safety OBSERVER Page 7
protect workers from potential exposure. This case
indicated the need for devices to detect and relieve
pressure in transfer piping and training in their use.
o Safe work practices should be developed and reviewed for
completeness prior to beginning a hazardous operation.
Pre-work briefings should be conducted to assure that the
safe work practices will be followed.
o Exposure to certain highly hazardous chemicals does not
cause immediate or obvious symptoms. Workers should be
trained to seek immediate medical evaluation after exposure.
This is imperative in the case of exposure to unknown
chemicals.
Inhalation of nitrogen
Leave Yourself Some Breathing Room
When working with new systems, troubleshooting and quick
fixes are often an integral part of getting things running.
Although changes may seem small or clear-cut, it is still
important to consider the effects they could have and to review
all the new circumstances that they bring with them. An incident
at Lawrence Livermore National Laboratory illustrates the
dangerous results that changes can cause.
(ORPS Ref. # SAN--LLNL-LLNL-1992-0018)
What happened
On February 13, 1992, one scientist from a national lab and
two visiting scientists from Japan were making final alignments
to install a laser-aided particle probe spectroscopy (LAPPS)
diagnostic on the Microwave Tokamak Experiment (MTX) Ä a plasma
fusion research device. The MTX has an operating temperature of
125 degrees Celsius. Because it was unclear what effect the high
temperatures would have on the LAPPS components developed by a
subcontractor, nitrogen gas was pumped into the area to cool the
LAPPS components. The visiting scientists were made aware of
this change. To determine if the final alignments were accurate,
one of the visiting scientists from Japan climbed onto the
platform to view the collection optics package. To get a better
view, the scientist lay on his stomach and placed a heavy cloth
over his head and shoulders, probably to block out the light.
Shortly after, the two other scientists joined him on the
platform. Within forty seconds they became concerned and removed
the cloth. He was found to be unconscious. The laboratory
scientist quickly called the emergency services who arrived on
the scene in an ambulance within 2 minutes. Artificial
respiration was initiated and the scientist was taken to the
health services where he began breathing on his own. He was then
taken to the hospital and released following a 2 week stay.
The accident investigation indicated that the direct cause
of illness was inhalation of the oxygen-deficient atmosphere in a
closed space created when he covered his head. Two contributing
causes were that none of the scientists recognized hazards
Page 8 Occupational Safety OBSERVER
created by nitrogen gas and that the impact of nitrogen cooling
on safety was not adequately reviewed.
Other factors contributing to the accident were that the
design process did not identify the incompatibility between the
electrical components in the collection optics package and
temperature of the MTX. In addition, the procedures did not
address the use of nitrogen gas. Hazardous control and
engineering personnel, who were not informed of the changes, were
unable to review the addition of nitrogen gas. In addition,
differences in language, training, and response to emergencies
among the LAPPS team may have contributed to the accident.
Finally, confined space training as required by LLNL's training
program manual was not provided to the LAPPS team.
Things to Consider
When working on complex experimental equipment, changes and
adaptations are frequently made. It is important to conduct a
safety analysis of modifications made along the way to ensure
that accompanying procedures are modified. In addition,
procedures should accurately reflect safety responsibility during
all phases of an experiment.
When working with nonlife sustaining or liquefied gases,
such as nitrogen, it is important that personnel working in
affected areas receive training to avoid circumstances like those
described here.
When introducing new equipment, it is important to have
equipment interface specifications to ensure safety and
efficiency, as well as adequate design reviews that will assure
compatibility and safety. Training on emergency procedures and
communication skills for teams with diverse backgrounds is also
important. Finally, assigning a single person to safety
responsibility may be useful in assuring that safety details are
not omitted.
LETTERS
The OBSERVER welcomes letters from its readers. We especially
appreciate any information that readers can provide to clarify
points in previous issues, or to add technical detail. Because we
make every effort to provide the most recent and useful
information to all DOE sites, we must sometimes go to press
before all investigations are complete, and occasionally space
limitations do not allow us to provide a great deal of technical
detail in the articles. The following are excerpts from some of
the letters we received regarding the December 1992 issue of the
OBSERVER.
Frank D. Beane, of the Princeton Plasma Physics Laboratory
Environmental Safety and Health Division, offers several items of
technical interest regarding electrical safety. He points out
that, when working with energized equipment, one of the items in
the line of defense is "the use of insulated tools and that
protective, flexible gloves should be mandatory" for work on
energized parts. He further suggests that:
Occupational Safety OBSERVER Page 9
o "The arcing caused by the wrench [in one incident] could
have been mitigated or avoided if the use of insulated tools
were required on live circuits and parts operated over
50-volts."
o "The potential shock hazard of circuits operated over
240-volts could have been mitigated if the use of
"Meterman's Gloves" (Class 0- to 1000-volt rated rubber
gloves with protectors made of doeskin for best flexibility)
were mandated within the context of an approved, generic
procedure."
Albert R. Chernoff, the Project Manager of the Uranium Mill
Tailings Remedial Action (UMTRA) Project, provides several points
of clarification on two articles involving incidents at UMTRA
sites:
o He notes that "a Type A investigation [of the electrical
incident at the Grand Junction site] has not been initiated.
However, a review of electrical safety on UMTRA Project
sites is underway, and the EH-1 Task Group on Electrical
Safety performed a review on November 10 and 11, 1992."
o Regarding the lockout/tagout incident that resulted in a
worker fatality, he points out that the nature of the
incident makes it impossible to know what actually occurred
in the incident: "There were ten scenarios, of which five
were the most likely, for how the mechanic got caught in the
feeder belt."
o He also notes that "the UMTRA Project sites are not under
the jurisdiction of Mine Safety and Health Administration
(MSHA). However, the UMTRA Project Office plans on
developing a Memorandum of Understanding to allow MSHA
inspectors to inspect UMTRA sites and recommend corrective
actions."
Page 10 Occupational Safety OBSERVER
DOE Order 5483.1A, dated June 1983, requires DOE compliance with
OSHA regulations, including those listed in the Observer.
The descriptions of the incidents included in this compendium are
based on information available at the time of publication.
The Occupational Safety Observer
is a publication of the
Office of Environment, Safety and Health.
For more information or corrections to the articles in this
issue, please contact:
Douglass Abramson
Operations Management Division (EH-32.1)
U.S. Department of Energy
Telephone: (301) 903-7328
For address changes and mailing list information, please contact:
John Everett
Fax: (206) 528-3246
Telephone: (206) 528-3246