LDX
Confined Space Entry
Plasma
Science and
Office of Environment, Safety, and Health
617-253-8440
(Catherine Fiore)
617-253-8917 (Matt
Fulton)
617-253-5982 (Bill Byford)
617-258-5473 (Nancy
Masley)
Fax 617-252-1808
Be Safe or Die
Reviewed and
Approved
By:
PSFC
Supervisor
Catherine
L. Fiore, PSFC Safety Officer
Title: Confined
Space Operation on LDX
Author: D. Garnier
Version: 1.0
Date:
Persons
Responsible: D. Garnier, J. Kesner, M. Mauel
Other Personnel:
See list of approved
personnel below.
Introduction:
This document will
outline the hazards
involved with working inside the LDX vacuum chamber.
It will also detail the procedures which will
be followed to minimize the risk to Plasma Science and
The LDX vacuum
vessel is a
cylindrically shaped structure with internal dimensions of 128" high
and
diameter of 196". The structure is made of stainless steel (no Inconel is involved).
A cross section is shown in Fig. 1.
The vacuum vessel is accessed via one of four side ports that
are 22” in
diameter. An alternate entrance point
will be the bottom flange that measures 42” but must be accompanied by
scaffolding platform raised to roughly less than 36” from the entrance
of the
vessel and that will be at least 42” by 42” in platform dimension.
Access to
the side ports will be available from the mid level platform and with
the
necessary stepladder to enable easy internal access.
At all times, at least two ports measuring no
less than 8” will be open such that a continuous airflow will
re-circulate the
entire volume (~1200 ft^3) of the chamber at least 40 times per hour.
Work inside the
vacuum vessel includes
installation of diagnostics, stud welding, chamber cleaning and
inspection.
The welding of the
studs (which are
3/4" long, 5/16" diameter) is accomplished with a stud-welding gun,
which uses up to 200 volts and 20 Amps. The stud is placed in the gun,
which is
then positioned at the desired location, and the trigger is pulled to
weld the
stud to the wall. The noise of the discharge is very loud and requires
some
hearing protection. Once these are welded, the area must be scrubbed
clean with
ethanol.
Chamber cleaning
will be accomplished
with acetone and ethanol solvents.
Solvents will be introduced to the space on moistened rags or
with a
plastic solvent dispensing bottle. In
order to ensure a safe environment, no more than 1 pint of solvent
shall be in
the chamber at any time. Also, use of
solvents should be limited to 1 pint in any one hour period.
Figure 1. Interior of the
LDX Vacuum Vessel
Scope:
This document is
designed to provide
for safe access to the interior of the LDX vacuum vessel.
Safety
Analysis:
Air quality is a
primary concern for working
inside the LDX vacuum vessel. The air must be monitored for oxygen
content and
for the buildup of combustible and hazardous fumes. Ethanol will be
used for
cleaning internal vacuum hardware. Personal oxygen monitors will be
provided
for those inside the vessel to monitor their oxygen content.
The potential for
electrical shock from
the welding machinery exists, as well as ultraviolet radiation. The
welding
could cause spattering from the welding arc and a buildup of welding
related
fumes (CO, metal oxides.) The stud-welding gun is very loud during the
discharge.
Injury could occur
from bumping into
structures and studs installed inside the experiment.
Also, when accessing the ceiling of the
vacuum space, an aluminum plank will be installed within the chamber. A fall hazard exists when working on the
plank.
Under certain
circumstances scaffolding
may be used to access space and in such cases, a fall hazard also
exists.
Definitions:
Confined
space
- means a space that (1) is large enough and so configured that an
employee can
bodily enter and perform assigned work; and (2) has limited or
restricted means
for entry or exit, and (3) is not designed for continuous employee
occupancy.
Entry -
means the action by which a person passes through an opening into a
permit-required space. Entry includes ensuing work activities in that
space and
is considered to have occurred as soon as any part of the entrant's
body breaks
the plane of an opening into the space. Entry permit means the written
or
printed document that is provided by the employer to allow and control
entry
into a permit space and that contains the information specified in this
document.
Hazardous
atmosphere - means
an atmosphere that may expose employees to the risk of death,
incapacitation, impairment
of ability to self-rescue, injury, or acute illness from one or more of
the
following causes: (1) Flammable gas, vapor, or mist in excess of 10% of
its
lower flammable limit (LFL); (2) Airborne combustible dust at a
concentration
that meets or exceeds its LFL; (3) Atmospheric oxygen concentration
below 19.5
% or above 23.5%; (4) Atmospheric concentration of any substance for
which a
dose or a permissible exposure limit is published in Subpart G,
Occupational
Health and Environmental Control, or in Subpart Z, Toxic and Hazardous
Substances, of this part and which could result in employee exposure in
excess
of its dose or permissible exposure limit; (5) Any other atmospheric
condition
that is immediately dangerous to life or health.
Oxygen
deficient atmosphere
- means an atmosphere containing less than 19.5% oxygen by volume.
Permit-required
confined space
(permit space) -
means a confined space which contains one or more of the following
characteristics: (1) Contains, or has a potential to contain a
hazardous
atmosphere; (2) Contains a material that has the potential for
engulfing an
entrant; (3) Has an internal configuration such that an entrant could
be
trapped or asphyxiated by inwardly converging walls or by a floor which
slopes
downward and tapers to a smaller cross-section; or (4) Contains any
other
recognized serious safety or health hazard.
Responsibilities:
The
Assistant Radiation Protection Officer for the PSFC shall
determine if the
Radiation Work Authorization Procedure (PSFC-RP-91006) and/or the ALARA
Procedure (PSFC-RP-91005) need to be implemented.
The
Entry Supervisor,
in addition to the responsibilities ascribed to confined space
entrants, is
responsible for overseeing the permit entry process. This includes:
1.
Preparation
and verification of permits. This includes verification that all
prescribed
tests and procedures have been performed, that all required equipment
is
available, and that rescue services and a means to summon them are
available.
This includes radiation work authorizations and ALARA reviews as well
as any
necessary welding permits.
2.
Monitoring
of the entry to see that conditions and procedures are consistent with
the
permit.
3.
Removal
of unauthorized persons from the area.
4.
Termination
or cancellation of an entry permit as required.
The
Confined Space Entrant
is responsible for:
1.
Understanding
the hazards associated with the confined space entry from all sources,
which
pertain: chemical (from MSDS), reduced O2, electrical, radiation,
engulfment,
mechanical, etc.
2.
Proper
use of all required equipment.
3.
Communication
with attendant.
4.
Recognition
of requirements for self-rescue, and proceeding with self-rescue when
necessary.
5.
Obeying
orders from the attendant and the entry supervisor.
6.
Complying
with all applicable safety procedures established for his/her project,
and with
the procedures established by the MIT Safety Office and by the MIT
Plasma
Fusion Center Safety Committee.
The
Confined Space Attendant
is responsible for monitoring and protecting confined space entrants.
This
includes:
1.
Understanding
the hazards associated with the confined space entry from all sources
which
pertain: chemical (from MSDS), reduced O2 ,
electrical, radiation, engulfment, mechanical, etc.
2.
Proper
use of all required equipment.
3.
Communication
with the entrant.
4.
Recognition
of requirements for self-rescue, and ordering the entrant to proceed
with
self-rescue when necessary.
5.
Ordering
evacuation if an uncontrolled hazard is detected, if the entrant
exhibits
behavioral effects of hazardous material exposure, if predetermined
entry times
are exceeded, if a situation develops outside the space, which could
endanger
entrants, or the attendant can no longer perform his/her duties.
6.
Summoning
rescue personnel as required.
7.
Following
instructions of the entry supervisor.
Assumptions:
Personnel allowed
access to the vacuum
vessel would be trained in confined space entry and rescue procedures
on the
vacuum vessel. The project supervisor will oversee this training and
approve
personnel for entry. A person capable of accessing the vessel must be
standing
by at any time workers are inside the vacuum vessel. A telephone will
be
available in the LDX cell where this work is being done. No more than 4
people
will ever be allowed inside the vessel simultaneously.
All personnel
approved to enter the
vacuum vessel will be trained in rescue procedures. At least one person
approved for access will be standing by at any time there is a worker
inside
the vacuum vessel. This person must maintain frequent verbal
communications
and, when possible, visual contact with the worker inside the vessel.
No person will be
required to remain
inside the vessel longer than he or she feels comfortable. Personnel
working
inside the vessel will be required to exit after 4 hours or less.
All required
permits, e.g., confined
space entry, radiation work authorization, or welding permits have been
obtained. All special equipment and protective clothing required by
these
permits have been obtained.
All external
hazards, e.g., ECRH,
magnet currents, glow discharge electrodes, gas puffing system, have
been
locked out.
Required
Equipment:
The space will be
ventilated at a rate,
which will provide 40 air changes per hour (approximately 900 cfm) or as specified by the Industrial Hygiene
Office. It
will be lighted with low voltage lights.
The attendant will be equipped with a flashlight in the event of
a power
failure. Continuous oxygen and flammable gas monitoring will be done at
all
times that the space is occupied.
Those working
inside the vacuum vessel
will wear protective clothing appropriate to the tasks, which they are
performing. Welding operations will require the wearing of leather
gloves,
protective eyewear, etc. Use of the stud-welding gun will require ear
protection. Flame retardant suits should
be worn during welding instead of Tyvek,
which burns
too easily.
Procedure:
Only personnel who
have had confined space
training and have been trained in entry and rescue techniques will be
allowed
to enter the vacuum vessel. A list of the approved persons will be
posted at
the site.
1.
The
ventilation system must be set up on the vacuum vessel and be operating
before
entry is attempted.
2.
An
oxygen and flammable gas monitor will be inserted into the vessel and
checked
before entry is attempted. This monitor must be operating at all times
that
personnel are inside the vacuum vessel. Anyone working inside the
vessel must
exit immediately if an alarm is registered on this meter. No one may
enter this
space if an alarm is registered. A maintenance schedule for this meter
is
attached to this procedure.
3.
Low
voltage lighting must be inserted into the vessel, or fluorescent port
lighting
fixtures must be turned on before entry is attempted.
4.
A
second person approved for entry into the vacuum vessel (confined space
attendant) must be standing by. This person must maintain frequent
verbal
communications and, when possible, visual contact with the worker
inside the
vessel. An additional person, capable of assisting with the removal of
a worker
from the vessel from outside of the vessel must be in the area as well.
5.
Materials
to be taken inside the vessel must be reviewed for toxicity by the
Industrial
Hygiene Office. Any precautions specified by IHO must be observed.
Vacuum
protective clothing must be non-flammable for welding and spot welding
applications.
6.
The
set up of any welding operations inside the vessel must be reviewed by
the
welding supervisor and approved for safety. The workers welding inside
the
machine must wear the appropriate clothing and protective gear.
7.
A fire
extinguisher must be available on the deck. The fire extinguisher on
the
scaffolding shall consist of one of the following three items: A water
hose
with spray nozzle; A bicarbonate of soda
dry chemical
fire extinguisher; or several fire blankets. The water or dry chemical
extinguisher is preferred.
8.
An audible
alarm must be available for emergencies. The fire pull alarms in the
cell are
deemed acceptable for this purpose. In an emergency situation, the
rescuers
should pull one of the fire alarm switches.
9. Any
person entering must be familiar with these
procedures. That person should verify for his or herself that the
oxygen-flammable gas monitor is installed, that the lighting is
provided from a
low voltage source, that the blower is operating, that the fire
extinguisher is
at hand, and that approved spotters are standing by.
10. These procedures
must be posted at the site.
In
addition the entry supervisor shall:
1.
Check
the entry procedure and make sure that all of the required equipment
has been
assembled.
2.
Make
sure that any ventilating equipment has been installed and is operating
satisfactorily.
3.
Check
that all required measurements of atmosphere have been performed and
that
levels are in a satisfactory range.
4.
Satisfy
him/herself that the attendants and entrants
understand
their responsibilities and the procedure to be followed.
5.
Fill
out the permit (blanks should be obtained from the ES&H office) and
post it
at the entry site.
6.
At
completion of the entry the entry supervisor shall return the permit to
the
ES&H office.
Training
• The
supervisor must observe this training and verify that the worker is
capable of
performing simple rescue techniques. The supervisor must also verify
that the
worker is capable of entering and exiting the vessel under his or her
own
power.
• Personnel
allowed access to the vacuum vessel would be trained in confined space
entry
and rescue procedures on the vacuum vessel. The project supervisor will
oversee
this training and approve personnel for entry.