Cover Sheet

Division serial number ___________________

Distribution:

copies to: affected area, authors, division EH&S officer

original: EH&S Reporting Manager

Purpose:

This TOSP is written to define the conditions for safe test of a partially configured Injector Test Stand Gun at 550 kV potential and a maximum 50 µA current while it is in the Test Stand Enclosure (Room 127) while using the Power Supply located in the Power Supply Enclosure (Rm 227A) and the high voltage cable system on the mezzanine. This document covers the safety precautions to be taken immediately before the supply is energized, during operation of the supply and immediately after the supply is de-energized. It also covers the Test Stand Enclosure "OPEN" mode when the terminal for the High Voltage Cable is exposed while in the Test Stand Enclosure. These measures reduce the hazards presented by the gun, supply and cable from High Risk to Low Risk.

Description:

The power supply is located on the mezzanine above the Test Stand Enclosure in a grounded enclosure called the Power Supply Enclosure. The disconnect switch for this supply is mounted next to the entrance door to the Enclosure. The supply is interlocked to the doors of its enclosure with dual, independent, redundant, interlocks such that an open door either prevents the supply from energizing or opening the door de-energizes the supply.

The shielded high-voltage cable that is attached to the supply passes through the side of the enclosure, through the mezzanine area and through an opening in the ceiling of the Test Stand Enclosure. The walls of this enclosure are made of concrete at least 15 in. thick. Note that this configuration allows personnel access to only the cable's grounded shield.

Once inside the Test Stand Enclosure, the cable terminates inside the SF6 Tank of the partially assembled Electron Gun. The two doors of the Test Stand Enclosure (the main double door on the north end and the exit-only door on the south end have identical interlocks as above that are part of the same safety circuit that will de-energize the power supply upon opening. The SF6 Tank is a grounded enclosure. Two cylindrical ceramic insulators form the volume in the electron gun that normally is evacuated. This volume will be under vacuum for this test but the cathode electrode and its stem will not be installed. The outer volume of the cylinders is exposed to SF6. The test associated with this TOSP is to apply 550 kV to the cable, its newly configured terminations in the SF6 volume and to the high voltage end of the stack of two ceramic insulators.

Authority and Responsibility:

The Authorized Operator of the power supply is limited to "authorized personnel only" as noted by a sign located on the door to the Power Supply Enclosure. That authorization is given to Jock Fugitt and Dave Engwall. It is their responsibility to operate the supply and enter the enclosures per the requirements of this TOSP. Authorized Operator responsibility transfers with the passing of the keys (mentioned under Hazard Controls below) to another person on the Authorized Personnel list.

Analysis of the Hazards

Four unusual hazards exist. The first is that a person can be inside the Power Supply Enclosure while someone else turns the power supply on. The second is that the stored energy of the system is greater than 100 J at 550 kV and does not instantaneously bleed down when the supply is de-energized. As the time of bleed down is greater than the time to open the door and enter the Power Supply Enclosure, a person could enter, not use the grounding stick, and touch the corona ring before the stored charge has dissipated. These two hazards are assessed at Class 4 because the Consequence Level is IV (Because the shock could be fatal) and the Likelihood Code is C for "Likely to happen, given sufficient time".

The third hazard is that accelerated particles in the evacuated portion of the insulator stack could generate X Rays when they hit material. The flux of these rays is limited by the current limit on the power supply which, for this test will be 50 µA. This hazard is assessed at Class 3 because the Consequence Level is III (because the radiation could cause moderate to serious injury) and the Likelihood Code is C for "Likely to happen, given sufficient time".

A fourth hazard presents itself after shut down during further construction and during maintenance. When the high voltage cable is pulled out of the tank and the termination remains in the enclosure, it is out of sight of its power supply's disconnect switch. This hazard is assessed at Class 4 because the Consequence Level is IV (Because the shock could be fatal) and the Likelihood Code is C for "Likely to happen, given sufficient time".

Hazards Controls:

All four hazards are mitigated to a Hazard Class 1 by the following administrative procedures during energizing and de-energizing. Though the severity of the outcome remains at level III or IV because of the nature of the voltage and radiation involved, the likelihood code drops to "A - Very unlikely to occur" because of the few people involved, their training and the procedures of this TOSP.

Energizing: and Operation

1. Prior to the start of the first test the RCG will verify, by observation, that the interlocks function according to intent and/or design. A written entry shall be made in the appropriate operations log indicating satisfactory completion of the interlock test.

2. The two enclosures shall be keyed with the same unique lock. Only one key ring with that lock's key on it shall be available and it shall be held by the Authorized Operator.

3. The operator shall verify that the interlocks on all three doors are in working order.

4. The Authorized Operator shall verify that the high voltage termination is installed in the SF6 Tank.

5. The Authorized Operator shall use Lock and Tag on the disconnect switch to the Power Supply. 6. The Authorized Operator shall unbolt the grounding strap to the high voltage end of the Power Supply.

7. The Authorized Operator shall sweep the Test Stand Enclosure of personnel, starting at the south personnel exit door (verifying that the one way door latch secures the door) and continuing to the main door on the north end. The Authorized Operator shall lock this door and verify that it is locked by attempting to turn the handle. Thereafter the Authorized Operator shall keep all keys to that lock on his person.

8. The Authorized Operator shall verify that the radiation blankets are covering the three openings in the ceiling of the Test Stand Enclosure that exit to the floor of the mezzanine.

9. The Authorized Operator shall sweep the Power Supply Enclosure and shall lock its door and verify that it is locked by attempting to turn the handle. He may remove his Lock and Tag (leaving the administrative lock in place) from the disconnect switch at this time.

10. Operation may begin only after these procedures have been completed and the Authorized Operator has removed the administrative lock from the disconnect switch of the Power Supply and has set the current limit to 50 µA.

11. During the first test, 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.

De-energizing;

1. The Authorized Operator shall turn off the disconnect switch for the Power Supply and lock out the disconnect switch with the administrative lock and his own Lock & Tag.

2. Authorized Personnel shall wait one minute before entering the Power Supply Enclosure after the power supply has been turned off. They shall enter with a grounding stick, 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. They shall attach a bolted grounding strap between the high voltage terminal of the Power Supply and Ground. This action eliminates the requirement for any further Lock & Tag on any one's part in either enclosure because the High Voltage conductor is turned into a grounded device.

3. Only after the above two procedures shall the Authorized Operator unlock the Test Stand Enclosure. The keys for the door and the administrative lock on the power supply disconnect switch shall be personally kept by one of the personnel authorized by this procedure.

4. Thereafter, all individuals involved in access to the shielded enclosure will be CEBAF trained radiation workers and shall be wearing CEBAF issued dosimeters.

5. On entry into the shielded enclosure after shutdown, at least one individual making entry shall wear an alarming, self reading pocket dosimeter supplied by the Radiation Control Group (RCG).

Operating Guidelines:

See above.

Training guidelines:

The authorized personnel above shall train additional operators in the requirements of this TOSP before passing on to them the authorization to be Authorized Operators. The authorization shall be recorded on the copy of the TOSP in the envelope on the door of the enclosure.

Unusual Emergency Procedures:

None.

Instrument Calibration Requirements.

None.

Record of additional Authorized Personnel:

I have read this TOSP and have been trained in its use by one of the original authorized personnel.

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Print Name Signature Date

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Print Name Signature Date

________________________________ __________________________________ __/__/ 96

Print Name Signature Date

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Print Name Signature Date