(Assigned by division EH&S officer when complete)
| Issue Date: | |
| Expiration Date: | |
| Title: | Injector Test Stand, 500 keV |
| Location: | Building 58, ITS Complex |
| Risk classification
(See EH&S Manual Chapter 3210.) | Without mitigation measures: 4 With specified measures implemented: 1 |
| Author(s): | G. Biallas/K. Jordan/P. Francis |
| Supplemental technical validations: | |
| Hazard reviewed: | Reviewer signature: |
| High Voltage | |
| Radiation | |
| Laser | |
| Signatures |
| Division EH&S officer, recommendation: |
| Department manager, approval: |
| Other approval(s): |
Distribution:
Copies to: affected area, authors, division EH&S officer
Original: EH&S Reporting Manager
Purpose of the Procedure:
The purpose of the procedure is to lower the risk of operation
of the Injector Test Stand (ITS) in the First Experimental Arrangement
per drawing # 09110-E-0004 (500 keV Beam) from High Risk to Low
Risk for the unusual hazards of that operation.
Description of Devices and Operations with Unusual Hazards
and their Mitigation:
General:
The Injector Test Stand consists of a High Voltage Electron Gun
with beam line and dumps in a cement enclosure, a High Voltage
Power Supply in a separate room, a drive laser in a separate clean
room and a control room. The Test Stand is installed near the
North east corner of the Test Lab.
All hazards are mitigated to a Hazard Class 1 by the use of the
Certified Personnel Safety System and by administrative procedures
detailed below. Though the severity of the outcome remains at
level III or IV because of the nature of the laser light, voltage
and radiation involved, the likelihood code drops to "A -
Very unlikely to occur".
A Personnel Safety System (PSS) is installed in the Test Stand
Enclosure. It is a system of interlocks connected to a PLC that
is able to shut down the high voltage power supply and close the
shutter on the drive laser beam when the PSS interlocks are tripped.
In addition it has logic and timing functions that require a
sweep of the Test Stand Enclosure before reset. The PSS operates
in the Open State, the Beam Permit State and the Laser Permit
State.
The Laser Permit State of the PSS permits laser light to enter
the Test Stand Enclosure while not permitting High Voltage. The
second of the two key switches on the PSS control panel in the
control room provides the logic to disallow permit for the high
voltage. The requirements for personnel using the Laser Permit
State are detailed in the LSOP. See the procedure below for the
procedure for establishing the Laser Permit State.
The Power Supply Enclosure has a set of redundant interlocks on
its door that are in independent from the safety circuitry of
the PSS. When disengaged, these enclosure interlocks remove the
permit to turn on high voltage.
The unusual hazards of the Injector Test Stand are high voltage,
radiation, Class 4 Laser and Oxygen Deficiency.
High Voltage - Power Supply Enclosure:
The High Voltage Power Supply for the Gun is located in the grounded Power Supply Enclosure (Rm 227A). The high voltage cable with grounded shield attaches to the Power Supply and penetrates through the wall of the Enclosure. In addition to High Voltage, one additional unusual hazard exists. Both hazards are detailed below:
| Hazard | ||||
| 1. | High Voltage: 530 kV, 4 mA | |||
| 2. | Stored energy of the system is greater than 100 J at 550 kV and does not instantaneously bleed down when the power supply is de-energized. As the time of bleed down is greater than the time to open the door. |
Hazard # 1 mitigated by :
Redundant interlocked doors on the Power Supply Enclosure
Warning beacon outside the Enclosure
PSS Permissive to the High Voltage
The cable on the grounding stick, attached to ground outside the enclosure, prevents the doors from closing and from making up the interlocks while it is in use.
The door of the Power Supply Enclosure is locked by lock with
a single, unique key
Hazard # 2 is mitigated by the following features of the locks
and interlocks and by the following required procedures for entering
and exiting the Power Supply Enclosure:
Procedure for entry to the Power Supply Enclosure
Authorized Personnel shall use LOTO on the disconnect switch on
the outside of the Power Supply Enclosure. They shall wait one
minute before entering the Power Supply Enclosure after the power
supply has been turned off. (Using the unique key to the Enclosure,
obtained from the Operator.) The turn-off of the warning beacon
has a programmed delay of this time period. Authorized Personnel
shall enter with the grounding stick that is located outside the
door, touch the stick to one toroid and, for the remainder of
the access, hang the stick to the connecting lug that connects
the two toroids.
Procedure for exit from and reactivation of the Power Supply Enclosure
To close the enclosure and reactivate the Power Supply, the Authorized
Personnel shall use LOTO on the disconnect switch on the outside
of the Power Supply Enclosure, enter the enclosure, observe that
no other personnel are in the enclosure, remove the grounding
stick, exit and lock the door, trying the door knob and thus
verifing the locked state. The key to the Enclosure shall be
placed in the Key Cabinet in the Control Room and LOTO shall be
removed.
High Voltage - Test Stand Enclosure:
From the point that the high voltage cable with grounded shield penetrates through the wall of the Enclosure and into the gun, the high voltage is always within a grounded enclosure during Beam Permit. In addition to High Voltage, one additional unusual hazard exists. Both hazards are detailed below:
| Hazard | ||||
| 1. | High Voltage: 530 kV, 4 mA | |||
| 3. | During Open State or Laser Permit State, the high voltage electrode surfaces or the end of the cable may exposed for maintenance. Personnel are out of sight of the high voltage power supply's disconnect switch. |
Hazard # 1 mitigated by :
Sweep of the enclosure per the procedure below
Redundant interlocked doors in the Test Stand Enclosure that are part of the PSS
Warning beacon outside the enclosure
Run Safe Box with lighted status windows for SAFE, OPERATIONAL and UNSAFE with a crash switch
TV camera at the north end (with only a limited view of the 70% of the enclosure) as a partial, last check for personnel inside the Test Stand Enclosure
PSS Permissive to the High Voltage
SF6 Tank Pressure permissive to the High Voltage
Hazard # 3 is mitigated by the validated PSS.
Radiation:
The Injector Test Stand Gun is a photo cathodic electron source capable of creating and intense electron beam at 500 keV (530 kV during conditioning) at a maximum current of 4 mA. The hazard of prompt ionizing radiation is due to the beam itself and X-ray emission caused by impinging electron beams and possible ion discharges
The radiation hazards are as follows:
| 4. | Prompt X-ray emission | |||
| 5. | Electron beam at 500 keV | |||
| 6. | Prompt radiation from the Dumps | |||
| 7. | Prompt Radiation leakage out of the penetrations |
Hazards four through six are mitigated by :
Sweep of the enclosure per the procedure below
Redundant interlocked doors that are part of the PSS
Warning beacon outside both enclosures and inside the Test Stand Enclosure
Audible warning and time delay of 30 sec. before High voltage permissive
Run Safe Box with lighted status windows for Safe, Operational and Unsafe with a crash switch
Magnetically locked entrance door to the Enclosure
PSS Permissive to the High Voltage
PSS Permissive to the Drive Laser
TV camera at the north end as a last check for personnel inside the Test Stand Enclosure
Hazard seven is mitigated by a required inspection of the shielding
of the penetrations by the Operator on a weekly basis, recorded
in the ITS Log.
The overall system hazard associated with a system reverting from
a source of prompt radiation to an open enclosure is mitigated
by the following requirement and the dosimeter requirement in
the section below titled: Going to the Open State or the Laser
Permit State
All individuals involved in access to the shielded enclosure will
be CEBAF trained radiation workers and shall be wearing CEBAF
issued dosimeters.
Routine shielding inspection will also be done by the RCG.
Class 4 Laser Light:
Hazards, which are described in the LSOP, are mitigated by :
Sweep of the enclosure per the procedure below
Magnetically locked entrance door to the Enclosure
Redundant interlocked doors that are part of the PSS
Warning beacon outside both enclosures
Run Safe Box with lighted status windows for Safe, Operational and Unsafe with a crash switch
Audible warning and time delay of 30 sec. before laser permissive
PSS Permissive to the Drive Laser
TV camera at the north end, that sees 70% of the enclosure volume,
as a last, partial check for personnel inside the Test Stand
Enclosure
During Laser Permit, a worker qualified per the LSOP may be locked into the enclosure.
These hazards and their mitigation are treated in detail in LSOP,
dated January 10, 1996, titled: Injector Test Stand.
Oxygen Deficiency:
A small gaseous nitrogen pipe in the ITS enclosure is attached
to the boil-off line on the Test Lab's Main Nitrogen Supply Dewar,
making the supply of nitrogen almost unlimited in the short term.
In the unlikely event of a break in this line, it is possible
that the enclosure becomes oxygen deficient. However, the Enclosure
has a continuous duty exhaust fan that keeps the atmosphere within
non ODH limits. Thus the Enclosure is classified as ODH 0.
With the fan off, the enclosure reverts to ODH 1.
This hazard is mitigated by ODH alarms that are placed at the 7 foot level and at floor level. Notification of ODH 1 status is by a beacon at the front entrance tripped by an air flow switch in the exhaust air duct.
Authority and Responsibility:
The person who is designated as the Operator has the responsibility
to operate the Test Stand at any one time per the requirements
of this OSP. The position of Operator is limited to "authorized
personnel only". Operators shall be appointed by the Core
Person for the Injector Test Stand.
The Operators of the Injector Test Stand shall be selected from
the qualified operators of the High Voltage Power Supply and/or
of the Drive Laser. Qualified operators are listed in Appendix
1. These personnel are authorized to instruct and qualify additional
personnel. A record of that qualification shall be kept in the
ITS Log Book and Appendix 1 to this OSP.
Verification:
Certification of the verification of the Personnel Safety System:
The Personnel Safety System shall be "certified" prior
to the start of operation. The Certificate of Verification shall
consist of a copy of the check list for verification pasted into
the control room Log Book with the signatures itemized below,
specifying the date and time of the verification and the date
of expiration. An additional copy shall be included as Appendix
2 of the OSP .
Verification Procedure:
To verify the PSS, a member of the control group shall exercise
all door interlocks on doors to the Injector Test Stand Enclosure,
Drive Laser Clean Room door and Power Supply Enclosure door.
In addition, the functionality of the magnetic locks, ODH Monitors,
the position and robustness of the radiation and optical shielding
at all the penetrations to the enclosure, the operation of the
audible and flashing beacons and the operation of the Run Safe
Boxes and their lights shall be verified. This verification procedure
shall follow the checklist that tests the logic of the chains
of safety for all states. A RCG staff member shall be present
to observe the verification. The checklist for verification shall
include signature blocks for the person verifying the system,
and a signature block for the RCG member to indicate observance.
The verifier shall explain all steps in sufficient detail so
that the observer is completely satisfied that all items and sequences
function correctly and as designed.
During the first test at high voltage, a member of the RCG shall
be on hand to verify the adequacy of the shielding for the Test
Stand Enclosure, with particular interest in the three rectangular
penetrations in the ceiling blocks.
Operating Guidelines:
Going to the Beam Permit State or Laser Permit State
Step 1. The Operator shall verify that the high voltage
termination is installed in the closed and pressurized SF6 Tank.
For the Beam Permit State only, The Operator shall use the Procedure
for exit from and reactivation of the Power Supply Enclosure
above if the Power Supply Enclosure is still open.
Step 2. Perform the sweep of the Injector Test Stand
(ITS) Enclosure. The sign above the Enclosure should indicate
ìOPENî at all times unless a sweep is being conducted
or a mode of operations is occurring. If nothing is being displayed
above the ITS enclosure, the enclosure has been secured but the
key has not yet been inserted and turned. All doors, front
and rear must be closed prior to a sweep. All crash buttons
at Run/Safe boxes must be pulled out prior to sweep. Otherwise
the safety system will not be operational and you can not start
the sweep mode. This status is displayed on the PSS chassis.
Step 3 Locate the PSS chassis, place the control key in
the switch corresponding desired mode of operation (Beam Permit
or Laser Permit) and turn key to the right (horizontal) position.
Step 4 Press the Initiate Sequence Button.
Step 5 Remove the control key. The sign above the ITS enclosure
should now be flashing OPEN.
Step 6 You now have 30 seconds to get through the front
door and close it. If this is not followed, the safety system
will crash and you will have to start over
Step 7 Once you are through the front door and it is closed, the mag lock will engage, keeping anyone else from entering the ITS enclosure. At this point, if you need to leave the enclosure before completing the sweep, you will crash the safety system. Ways to leave are :
1. Depressing the crash button at the run/safe boxes located at the front of the enclosure or at the rear of the enclosure.
2. opening up the rear door of the enclosure.
3. Placing the control key in the front run/safe box and turning
the key before doing the rear run/safe box.
Step 8 Once you are inside the ITS enclosure with the
front door mag lock engaged, you begin your sweep of the enclosure.
Front to back, back to front, arming the Rear Run/safe Box first
and then the Front Run/safe Box last. Look for people in all
possible locations. Do not arm the front run/safe box first
or it will crash the safety system and you will have to start
the sweep process all over again. Push on the rear door to
ensure it is properly locked. Once you have reached the rear
run/safe box, note its condition. The SAFE sign should be flashing.
If not, hit the crash button and call the safety system technician
to investigate. Insert the control key and
turn. The rear run/safe box should now show OPERATIONAL lit with
SAFE flashing. If not, hit the crash button and call the safety
system technician to investigate. Remove the control
key and sweep back to the front run/safe box.
Step 9 Once you have reached the Front Run/safe Box, note
its condition. The SAFE sign should be flashing. If not,
hit the crash button and call the safety system technician to
investigate. Insert the control key and turn. The Front Run/safe
Box should now show OPERATIONAL lit with SAFE flashing. If
not , hit the crash button and call the safety system technician
to investigate. At this point the front door mag lock
should disengage allowing you to exit the enclosure. Do not
allow any person to enter the enclosures as you exit for their
own personal safety. Exit the enclosure and close the door
behind you. If you leave the door open, when you insert the
control key into the safety system chassis, it will crash the
safety system and you will have to restart the sweep process all
over again. The front run/safe box should now
show OPERATIONAL. Observe this through the front door window.
The sign above the ITS enclosure entrance should show nothing.
The enclosure is now secure for Laser Permit or Beam Permit .
Step 10 Enter the control room and place the control key
in the switch for the desired mode of operation. If laser
permit was initiated at the beginning of the sweep mode, the control
key will only work in the laser permit slot and vice versa for
beam permit. Turn the key. Depending on location of the control
key, 1 of 2 scenarios will occur:
1. If the control key is in laser permit, a prerecorded message
will now be aired over the PA system, the sign above the ITS enclosure
will now indicate LASER PERMIT, the run/safe boxes inside the
enclosure will now show UNSAFE and 30 seconds later the laser
shutter will open, allowing laser operations.
2. If the control key is in beam permit, a prerecorded message
will now be aired over the PA system, the sign above the ITS enclosure
will now indicate BEAM PERMIT, the run/safe boxes inside the enclosure
will now show UNSAFE. After 30 sec. the 500 kV Power Supply interlocks
will engage and 30 seconds later the laser shutter interlock will
make up, allowing beam operations.
If it is desired to stop the mode of operations but still leave
the enclosure secured, simply remove the control key. The front
and rear run/safe boxes inside the enclosure will now indicate
OPERATIONAL, the sign above the ITS enclosure will indicate nothing
and if you were in laser permit mode the laser shutter will close
or if you were in beam permit mode, the laser shutter would close,
and the 500 kV interlocks will open. To return to the original
mode of operations simply place the control key back in its original
position and turn. (see Step 10.) If it is desired to stop the
mode of operations all together, simply punch the crash button
on the safety system chassis. See below
Going to the Open State or the Laser Permit State
In the Open State or the Laser Permit State, the PSS protects
personnel from high voltage and radiation with redundant systems.
No LOTO is required.
On entry into the shielded enclosure after shutdown of the high
voltage, at least one individual making entry shall wear an alarming,
self reading pocket dosimeter supplied by the Radiation Control
Group (RCG). There shall be a log entry to indicate that this
step has been followed for each initial entry after the HV has
been de-energized. This requirement shall no longer apply upon
placement and use of a local alarming radiation detection device
in the test cave, visible upon entry.
Training requirements:
The authorized personnel above shall train additional operators
in the requirements of this OSP before passing on to them the
authorization to be Operators. The authorization shall be recorded
in Appendix 1 of this OSP.
Unusual Emergency Procedures:
Upon loss of power, the Operator shall initiate the procedure
for going to Open State.
Instrument Calibration Requirements.
None.
Inspection Schedules:
ï The PSS shall be verified every six months.
ï The state of the radiation shielding on penetrations shall be inspected weekly.
ï The ODH Monitor System shall be verified every six months.
ï Any change to the PSS requires a review of this OSP by the same reviewers and requires recertification of the PSS.
Qualified Operators of the High Voltage Power Supply:
1. Jock Fugitt
2. David Engwall
3. Charles Sinclair
Qualified Operators of the Drive Laser (Per LSOP - Injector Test Stand)
1. Steve Benson
2. Paul Davidson
3. David Engwall
4. Wael Ibrahim
5. Kevin Jordan
6. George Neil
7. Michelle Shinn
8. Jinhu Song
9. Tim Siggins
10. Trey Thurman
Verification Procedure for the Injector Test Stand PSS
1. Lock and tag the 500 kV power supply as per CEBAF lock
and tag procedures.
2. Post a sign on the test enclosure door that you are
going to test the interlocks and notify any personnel in the enclosure
that they must leave.
3. Follow the procedure above titled Going to the
Beam Permit State or Laser Permit State to secure the
enclosure for Beam Permit and Laser Permit, leaving someone inside
of the enclosure.
__/__3A Verify that the audible warning is given in the 30 seconds
before Permit is actuated.
__/__4. With the PSS in beam permit verify that the sign
over the test enclosure door, the status panel on the PSS chassis,
and the 500 kV power supply status panel in the control room all
indicate BEAM PERMIT or LASER PERMIT (personnel safety system
green beacon for the PSS status). Additionally, call the enclosure
(X7221) and verify that the under BEAM PERMIT both the magenta
and the amber beacons in the enclosure are flashing. (In LASER
PERMIT, only the amber should be flashing.) and that both run/safe
boxes indicate UNSAFE.
5. Instruct the person in the enclosure to open the rear
door. Then verify that all of the aforementioned indicators return
to open or safe status.
6. Repeat steps three and four but tape cardboard spacers
on the two front doors maglock plates prior to securing the enclosure.
7. Repeat step five with the left front door.
8. Repeat step three through seven but with the right
front door.
9. Repeat steps three and four and now check the crash
button on each of the two run/safe boxes drop the system.
10. Repeat steps three and four and now check that the
two crash buttons in the control room drop the system.
__/__11.Modify step three for Beam Permit and Laser Permit by
attempting to put the key in the opposite lock after the sweep
and turning the key horizontal. The system should not go to the
opposite State.
____12. After securing the Enclosure in the Laser Permit State
in a real exercise, without someone in the Enclosure and with
the LOTO removed from the Power Supply, attempt to turn on the
High voltage Power Supply. It should not turn on.
__/__13. Post a guard at the Enclosure entrance to not let anyone
in. Crash the PSS to the Open State. Attempt to open the Laser
Shutter and turn on the High Voltage Power Supply. They should
not operate.
Verifier
Date
Observer
Date