PSFC-CH-95004

Authors: Catherine L. Fiore, Chris Reddy, Joe Bosco

Version: 3.3

Date: 1/16/96, Updated 5/30/03 by C. Fiore

Persons Responsible: Gary Dekow - NW21-106

Introduction

The Alcator C-Mod experiment will operate discharge cleaning on several occasions using a mixture of diborane (10%) and helium. Diborane is highly toxic and flammable. This document postulates several emergency situations, and details what is to be done if they arise.

Scope/Purpose

This document covers the emergency procedures for the Alcator C-Mod Diborane facility.

Consequences of procedural failure

Failure to properly react in the event of emergency could result in the unnecessary exposure of personal to harmful levels of diborane gas. Diborane is immediately dangerous to life and health at 40 ppm, and an explosion hazard at 9000 ppm.

Definitions

MDA-TLD-1 Gas monitor for the diborane system. One is located at the diborane gas cabinet. The other is located close to the igloo mounted on the diagnostic stand near the diborane cabinet.

SCBASelf Contained Breathing Apparatus. Two units are located at the entrance to the C-Mod power room, in the control room. Two more units are currently being purchased. Until these are on site, two units should be borrowed from the MIT Industrial Hygiene Office in building 56 and kept on site during a boronization process.

Responsibilities

Emergency response will be the responsibility of two of the following people:

1. Catherine Fiore,
2. Andy Pfeiffer,
3. Jim Irby,
4. Gary Dekow,
5. Bill Cochran,

These procedures will be reviewed and approved by a committee of no less than 3 knowledgeable persons, appointed by the Safety Officer.

Required Equipment

• SCBA

• Wrenches for gas fittings

• Walkie-talkies or cell phones

Required Materials

Assumptions and Prerequisites

It is assumed that the diborane monitors are installed in the cell and are functioning, as detailed in the diborane system test procedure.

It is assumed that an alarm on the diborane monitors triggers a loud bell and annunciator, and that all personnel will evacuate the cell and power room in response to this alarm.

If any element of the diborane safety system is not operational, the diborane is to be removed from the cell. (Refer to Procedure for Installation/Deinstallation of Diborane Gas.)

Procedure

Note: The diborane alarm signal latches once it is triggered, and must be reset at the detector in order to stop the alarm. Ocasional problems with the meters have triggered faults at times when a diborane leak was extremely unlikely to have occurred. In the event that an alarm is sounded at a time when the bottle is locked in the cabinet and it has not been opened, it is most likely safe to check and reset the meter if the following conditions are true:

1. Both monitor readings at the Diborane PLC read 0ppb and their history registers 0ppb.
2. The cabinet pressure is negative
3. No problem can be seen on the visual tv monitor at the cabinet (channel 27).

If these conditions are verified, then a pair of workers should proceed to the cell, maintaining verbal contact with workers in the control room to check for and correct a meter fault.

If the diborane bottle has been opened or there is any sign that the bottle or gas cabinet has been breached, use the following emergency procedures.

1. SCBA personnel in trouble.

   SCBA users always work in pairs. It is most likely that if one SCBA person gets into trouble, the other will be able to summon help via the radio, the cell phone, or by exiting the cell to ask for assistance. If at any point an emergency occurs, EMT's should be summoned by dialing 100 before taking any other steps.

   In any event, the rescuers must make reasoned judgements about the extent of risk they are willing to take in the case that assistance is needed.

   Any rescuer needs to ascertain the cause and circumstances surrounding the emergency in order to avoid adding more victims or aggravating injuries. Sound and reasoned judgement must be brought to bear in a case such as this. If the diborane bottle valve is closed, and the exhaust system is functioning, and the diborane monitors are reading 0, then it may be best to proceed with rescue without SCBA gear, especially if it appears that time is critical. (The exhaust system can be checked by looking at TR8 on the CRYBOR screen. It should be reading greater than 0.25")

   Several possible scenarios could result in the necessity of rescuing one of the SCBA wearing personnel, not all related to the toxic gas system. These include accidental injury by fall or impact, heart attack or other spontaneous medical event, failure of the SCBA, inhalation of toxic gas, or explosion of the toxic gas system.

   The first step of the rescuers should be to summon the EMT's. The standby personnel should then don the SCBA and come to the aid of the persons in the cell. One of them should take all possible steps to secure the gas system, i.e., shut the manual valve on the gas bottle if it can be reached safely. If they judge it safe to do so, they could try to remove the victim to a safe location if the cell cannot be rendered safe to proceed with treatment.

   Should the people in the control room lose contact with both SCBA entrants, then the EMT's should be summoned immediately. The backup team can then don the SCBA and carefully enter the cell to try and find the problem. An extra diborane meter is located in Catherine Fiore's office and can be used to check the atmosphere if necessary. This should be done very cautiously in order to avoid having additional victims.

2. Diborane leak detected in gas box or cell, cell closed.

   1. Set the TV to channel 27 to monitor the gas cabinet.

   2. Check the status of the diborane system on the PLC. The automatic valve (PV5) above the diborane bottle should have closed at the alarm initiation.

   3. If this valve has closed, monitor the output of the diborane detector. It updates once every minute. If the level does not decrease after several minutes, institute a Purge5.

   4. If the level still does not decrease after several minutes, summon two people from the emergency contact list. Notify the Industrial Hygiene Office that backup is needed. Call 3-2596 (the Industrial Hygiene Office) between the hours of 9 to 5. Outside of regular working hours, call the facilities operations center(3-1500) and ask them to notify the on call Industrial Hygienist, specifying that two additional SCBA units may be needed, if they are not already four sets in the control room. If at any point, it appears that a fire is in progress, dial 100 to activate a full emergency response. (Set the tv camera to channel 27 to monitor the cabinet.) If no fire is indicated, proceed to the next step.

   5. Two qualified persons should don the SCBA apparatus and prepare to enter the cell. Once two additional SCBA qualified persons have arrived and two additional SCBA units are on site, the first crew may enter the cell. They must maintain radio or cell phone contact with the backup SCBA crew. (Those wearing SCBA need to hold the walkie-talkie under the air outlet on the mask to make themselves audible.) They should proceed to close the valve at the diborane bottle. They should check the diborane monitor which is exhibiting an alarm and verify visually that it is reading at an alarm level. If it is reading 0 at the meter, then the tape can be inspected visually for brown dots which indicate that a diborane leak did actually occur. They should then exit the cell.

   6. If a leak is confirmed on the tape, a PURGE 60 should be done once the bottle valve is closed and the SCBA crew has exited.

   7. The cell evacuation should remain in effect until the diborane monitor indicates that the diborane level has fallen to a safe level. Once it has, the cell can be entered to reset the toxic gas monitor and to assess the reason for the fault.

   8. If a leak is confirmed, and PURGE60 does not clear it, dial 100 and tell them that there is an uncontrolled toxic/flammable gas leak. Make sure they summon the on-call Industrial Hygienest as well as the fire department.

3. Diborane leak detected in gas box or cell, cell open.
   All personnel must evacuate the cell. If the cell has not been closed, then it is assumed that there is no diborane in the process lines, and that any leak must be in the region of the gas bottle. Therefore, no attempt to purge the gas lines needs to be made.
   1. If this valve has closed, monitor the output of the diborane detector. It updates once every minute. If the level does not decrease after several minutes, summon two people from the emergency contact list. Notify the Industrial Hygiene Office that backup is needed. Call 3-2596 or ask the physical plant operations to notify the on call Industrial Hygienist, specifying that two additional SCBA units may be needed, if they are not already there. At any point, if it appears that a fire is in progress, dial 100 and activate a full emergency response. (Set the tv camera to channel 27 to monitor the cabinet.)

   2. Two qualified persons should don the SCBA apparatus and prepare to enter the cell. Once two additional SCBA qualified persons have arrived and two additional SCBA units are on site, the first crew may enter the cell. They must maintain radio or cell phone contact with the backup SCBA crew. (Those wearing SCBA need to hold the walkie-talkie under the air outlet on the mask to make themselves audible.) If the cell is open, the manual valve on the diborane bottle should not be open or have been opened. They should first attempt to reset the meter which is in alarm. Then they should verify that the valve at the diborane bottle is closed. They should check that the gas cabinet has not been damaged in some manner to start a gas leak. If the meter can be reset and is reading 0, then the tape should be inspected visually for brown dots which indicate that a diborane leak did actually occur. If it is clear, the cell can be returned to normal access.

   3. If the meter appears to be malfunctioning, then the spare MDA-TLD1 should be obtained from Catherine Fiore's office. It should be supplied with a fresh tape and used to verify that the cell and gas cabinet are free from diborane gas. It can then be swapped with the malfunctioning instrument, which can be removed for diagnosis and repair. If no spare meter is available and it is certain that the problem is due to meter malfunction, then the diborane bottle should be removed from the cell until the meter can be returned to service. (Refer to Procedure for Installation/Deinstallation of Diborane Gas.)

   4. The cell evacuation should remain in effect until the diborane monitor indicates that the diborane level has fallen to a safe level. Once it has, the cell can be entered to reset the toxic gas monitor and to assess the reason for the fault.

4. Fire in cell

   1. Evacuate the cell and building and summon emergency response personnel by dialing 100. Inform them that an MIT Industrial Hygienist will be needed in addition to the normal notification list and the fire department.

   2. A command center will be set up outside the building by the emergency response team. Go to the person in charge and inform him of the presence of toxic, flammable diborane gas in the cell, and tell them where it is located.

   3. No PSFC personnel should take further action unless directed to do so by the person directing the emergency response on behalf of MIT Facilities or Cambridge Fire Department.

5. Damage to the diborane gas cabinet

   1. If diborane gas is detected, and it is expected that an extensive release is occurring, evacuate the building by pulling one of the fire pull boxes. Dial 100 and initiate emergency response just as in the case of a fire, requesting the presence of an Industrial Hygienist in addition to the normal notification list and the fire department. Continue the procedure for having a fire in the cell.

   2. If no diborane gas is detected, and there is no reason to suspect a malfunction of the diborane gas monitor, then two of the designated emergency personnel will prepare to don SCBA in order to assess the situation. They should proceed with step 3.

   3. Notify the Industrial Hygiene Office that backup is needed. Call 3-2596 or ask the physical plant operations to notify the on call Industrial Hygienist, specifying that two additional SCBA units are needed if two extra units are not already at the site. At any point, if it appears that a fire is in progress, dial 100 to activate a full emergency response as in section IV.

   4. Two qualified persons from the emergency response list should don the SCBA apparatus and prepare to enter the cell. Once two SCBA qualified persons have arrived and two additional SCBA units are on site, the first crew may enter the cell. They must maintain radio or cell phone contact with the backup SCBA crew. They should examine the status of the cabinet and gas bottle, and proceed to close the valve on the diborane bottle. If the integrity of the gas cabinet is compromised, they should remove the gas bottle and block it (replace the plug, which is stored with the diborane bottle), and remove it to the exterior gas storage shed. (Refer to Procedure for Installation/Deinstallation of Diborane Gas.) If it is to be removed, they should ask the contact person in the control room to see that unnecessary personnel leave the area along the transport route, i.e. the control room and main hall of NW21. Note: Catherine Fiore has the key to the gas cabinet and to the toxic gas shed in her key box. If necessary, the gas bottle can be placed in the vacuum shop hood temporarily until that key can be obtained. Bill Byford and Rejean Boivin know how to access the key box in Catherine's Office.

6. Power outage during boronization

   Maintain the periphery in a locked and secured status. Remain in the control room until power is restored. If diborane is in the vacuum vessel, contact Bob Childs or Tom Toland and get them to come in to ensure that Torvac is properly restarted once power has been restored. Notify Gary Dekow or Catherine Fiore and get them to come in if they are not already there. Evacuate the machine and initiate the diborane shutdown procedure once it is safe to do so. Do not enter the cell without SCBA under any circumstances!

Checklist

1. If a fire in progress then
   1. Pull the nearest fire alarm.
   2. Dial 100.
   3. Inform the emergency personnel that a fire is in progress and that toxic flammable gas could be involved.
   4. Request that the on call Industrial Hygeniest be summoned.
   5. Await the fire department outside the building and inform them of the situation.

2. If the gas cabinet been damaged then
   1. If diborane gas leak has been detected then
      1. Pull the nearest fire alarm.
      2. Dial 100.
      3. Inform the emergency personnel a toxic flammable gas is in uncontrolled release, and that a fire could erupt spontaneously.
      4. Request that the on call Industrial Hygeniest be summoned.
      5. Await the fire department outside the building and inform them of the situation.
   2. Otherwise, proceed with removal of the diborane gas bottle. (Refer to Procedure for Installation/Deinstallation of Diborane Gas.)

3. If a diborane gas leak been detected and the cell is locked out then
   1. Summon backup SCBA qualified personnel.
   2. Ensure that a total of 4 SCBA units are on hand.
   3. Verify that PV5 has closed.
   4. Initiate a Purge5.
   5. If the diborane level returns to zero then
      1. Once 4 SCBA qualified personnel and 4 SCBA units are on hand, two people should don the SCBA units.
      2. The SCBA persons should enter the cell and shut the diborane gas botttle valve.
      3. The SCBA persons should reset the diborane monitor.
      4. The SCBA persons should exit the cell.
      5. A purge 60 should be initiated to remove the remainder of the gas from the system.
      6. The cell should be reentered, and the diborane tapes checked for brown spots.
      7. If the tapes indicate that there was no actual diborane leak, then the process can be resumed under the assumption that it was a false alarm.
      8. If a the tapes indicate a true release, then the system must be repaired and leak checked before proceeding.
   6. If the diborane level does not return to zero then
      1. Summon a person knowledgeable in the PLC ladder logic for the diborane system.
      2. Once 4 SCBA qualified personnel and 4 SCBA units are on hand, two people should don the SCBA units.
      3. The SCBA persons should enter the cell and shut the diborane gas botttle valve.
      4. The SCBA persons should exit the cell.
      5. A purge 60 should be initiated to remove the remainder of the gas from the system. This will require overriding the interlock in the PLC ladder logic which prevents PV5 from opening while the diborane monitor is in alarm.
      6. If the the diborane meter has returned to zero then proceed with deinstallation of the diborane gas bottle. (Refer to Procedure for Installation/Deinstallation of Diborane Gas.)
      7. Otherwise
         1. Pull the nearest fire alarm.
         2. Dial 100.
         3. Inform the emergency personnel a toxic flammable gas is in uncontrolled release, and that a fire could erupt spontaneously.
         4. Request that the on call Industrial Hygeniest be summoned.
         5. Await the fire department outside the building and inform them of the situation.
4. If diborane gas leak has been detected and the cell is not locked out for boronization then
   1. Evacuate the cell
   2. Assemble 4 SCBA qualified people.
   3. If the diborane reading on the Crybor PLC has returned to zero then
      1. Have two SCBA qualified persons don SCBA and enter the cell.
      2. They should reset the meter.
      3. They should check the diborane meter tape.
      4. If there is no evidence of diborane (brown circles) on the tape, they can exit and re-open the cell.
      5. If there is evidence of diborane, they should return to the control room and proceed to deinstall the diborane gas bottle. (Refer to Procedure for Installation/Deinstallation of Diborane Gas.)
   4. Otherwise
      1. The backup diborane monitor should be obtained and set up with a fresh diborane tape.
      2. Two SCBA qualified persons should don SCBA and enter the cell, with the backup diborane monitor operating. If this unit goes into alarm they should exit immediately and proceed to step 4.
      3. They should check the diborane monitor tape on the alarming unit and verify that diborane gas is present, by checking for brown spots on the tape.
      4. If the presence of diborane gas is confirmed, then
         1. Pull the nearest fire alarm.
         2. Dial 100.
         3. Inform the emergency personnel a toxic flammable gas is in uncontrolled release, and that a fire could erupt spontaneously.
         4. Request that the on call Industrial Hygeniest be summoned.
         5. Await the fire department outside the building and inform them of the situation.
      5. If there is no evidence of diborane on the tape, and the meter cannot be reset, then they should replace it with the backup unit.
      6. If this does not work, then the diborane gas bottle should be deinstalled until the problem is resolved.

5. If building power is lost:
1. Remain in the control room until the power is restored.
2. Contact Gary Dekow or Catherine Fiore and get one of then to come in.
3. If the vacuum vessel has been filled with diborane gas, call Bob Childs or Tom Toland and get one of them to come in.
4. If necessary, have Bob or Tom restart Torvac and evacuate the vacuum vessel. If cell entry is required for restart, it must be done by two SCBA qualified persons using the SCBA.
5. Proceed with the diborane shutdown procedure.

Training

Cross references

• Procedure for Installation/Deinstallation of Diborane Gas.

• Procedure for Diborane Gas System Discharge Cleaning.

• Procedure for Diborane Gas System Maintenance.

• Test Procedure for Diborane Gas System.

• Safety Analysis Report for Diborane Injection in Alcator C-Mod

Distribution

E. Marmar, J. Irby, C. Reddy, R. Clifford, J. Bosco, B. Childs, I. Hutchinson, F. Silva

References

• Matheson gas catalogue.

• MDA Scientific `` TLD-1 Toxic Gas Detector Operating Instructions''

• Diborane MSDS

This page maintained by Catherine L. Fiore FIORE@PSFC.MIT.EDU