BUM Mail 98: draft disaster plan

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Dear colleagues,
Here is a draft disaster plan based on the responses I had to my initial =
query. This generated some interest and I had requests for a summary. =
I would be grateful for any comments about the suitability of these =
actions. NOTE: these are draft recommendations only and I cannot accept =
responsibility for how suitable these are for any system. =20
Regards,
Lachlan Graham
DRAFT NMR/MRI DISASTER PLAN

The best procedure is to avoid problems by correct maintenance however =
this plan lists some emergency situations associated with =
superconducting magnets and suitable action. If at all possible the =
magnet manufacturers should be contacted if there is any doubt about =
what to do in a crisis. Some of these suggestions have come from the =
Bruker Users Mail subscribers and I acknowledge their suggestions.

1. Quench - Here there is a rapid boiloff of helium as the magnet =
becomes resistive. Personnel should leave the magnet room if this =
happens to avoid possible suffocation and only return when it is safe to =
do so. Any ventilation should be activated to bring fresh air into the =
facility and extract any boiled off cryogens. Opening external doors or =
windows may also be a good plan. A further possible problem is that the =
nitrogen tank may start to suck in air which could lead to ice blockage =
of nitrogen vents. This could be prevented by placing cut off rubber =
glove fingers or similar over the nitrogen vent tubes loosely such that =
they will be blown off if positive flow recommences. I would be =
interested in further comments about appropriate action here.

2. Ice plug in vent - Use a stream of high purity room temperature gas =
of the appropriate type (helium for helium vent, nitrogen for nitrogen =
vent) to melt out the plug.

3. Ice in magnet bore - Vacuum may be lost which will significantly =
increase boiloff. Contact Bruker on whether magnet can be repumped or =
needs to be de-energised and warmed up.

4. Dangerously low helium level - If you cannot refill in time contact =
Bruker to talk you through discharging the magnet. Prevention is the =
best policy here and helium fills say two weeks before there would be a =
problem would be a good policy.

5. Metal object stuck to magnet - If it does not cause a quench the =
magnet may need to be de-energised to remove it depending on location=20

Dr L.J.W. Graham
CSIRO DBCE
PO Box 56
Highett
Vic 3190
Australia
Phone int 61 3 9252 6000
Fax int 61 3 9252 6240

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DRAFT NMR/MRI DISASTER PLAN

The best procedure is to avoid problems by correct maintenance = however this=20 plan lists some emergency situations associated with superconducting = magnets and=20 suitable action. If at all possible the magnet manufacturers should be = contacted=20 if there is any doubt about what to do in a crisis. Some of these = suggestions=20 have come from the Bruker Users Mail subscribers and I acknowledge their = suggestions.

1. Quench - Here there is a rapid boiloff of helium as the magnet = becomes=20 resistive. Personnel should leave the magnet room if this happens to = avoid=20 possible suffocation and only return when it is safe to do so. Any = ventilation=20 should be activated to bring fresh air into the facility and extract any = boiled=20 off cryogens. Opening external doors or windows may also be a good plan. = A=20 further possible problem is that the nitrogen tank may start to suck in = air=20 which could lead to ice blockage of nitrogen vents. This could be = prevented by=20 placing cut off rubber glove fingers or similar over the nitrogen vent = tubes=20 loosely such that they will be blown off if positive flow recommences. I = would=20 be interested in further comments about appropriate action here.

2. Ice plug in vent - Use a stream of high purity room temperature = gas of the=20 appropriate type (helium for helium vent, nitrogen for nitrogen vent) to = melt=20 out the plug.

3. Ice in magnet bore - Vacuum may be lost which will significantly = increase=20 boiloff. Contact Bruker on whether magnet can be repumped or needs to be = de-energised and warmed up.

4. Dangerously low helium level - If you cannot refill in time = contact Bruker=20 to talk you through discharging the magnet. Prevention is the best = policy here=20 and helium fills say two weeks before there would be a problem would be = a good=20 policy.

5. Metal object stuck to magnet - If it does not cause a quench the = magnet=20 may need to be de-energised to remove it depending on location =