General Risk Assessment Form
Date: (1)
Updated 09/09
Reviewed
Sept 11 RJT
March 2015 J.Pater
Particle Physics Group
Assessed by:
(2)
Validated by: (3)
NEMO GEIGER CELL TEST RIGS
Location: (4)
Assessment ref no (5)
5-19 clean room suite
J.Pater
2
Review date: (6)
March 2016 or
major change of
operation or gas
Task / premises: (7)
Cosmic ray tests of Geiger Mode Drift cell prototypes for Supernemo expt.
Involves Helium/argon Gas + 4% ethanol. 1l /min, few mbar overpressure
HT: 2Kv / few uA to drift cells
Electronics / Data acquisition
Restricted access to clean room
24 h unattended operation Activity (8)
Hazard (9)
Gas
Cylinder
Handling
Person(s) in
danger (10)
Operator, others
in vicinity
Gas
Excess
Pressure
Operator, others
in clean room
Gas
4% ethanol
Vapour in gas
Exposure/
flammability
Operator, others
in clean room
Existing measures to control risk (11)
1) standard cylinder handling protocols
2) Trolley transport
3) Minimise no of cylinders stored
1) only few mbar overpressure, bubbler to
vent./overpressure vent valves 100 mbar
2) metal piping / vessel leak tight system.
1) metal piping / Metal vessel leak tight system.
2) Ethanol in inert Gas stream , vent to extract
system Diluted to below LEL
3) small Quantities ~ 1l ethanol in bubbler,
Consumption ~5ml/hour
4) Operation in clean room – very high air flows
even if extract fails See calculations
5) Valves default to off if mains failure
6) N2 for system purge
Risk rating (12)
Result
(13)
A
Low Risk
Low risk
A
Low risk
A
Activity (8)
Hazard (9)
Filling ethanol
bubbler
Person(s) in
danger (10)
Operator, others
in clean room
Vac Pump
Existing measures to control risk (11)
Risk rating (12)
1) use small pump type dispenser on Winchester,
not open pouring
2) operator training
3) Ethanol Bubbler in outer Perspex box
Electrical
2Kv/ few uA to
Experimental
Drift cells
Potential
Electric shock
Risk if partially
disassembled
for
investigation
Operator, others
in clean room
1) Scroll Pump so no oil
2) Output to extract
1) Sealed device , Screened Cables
2) Current limiting Series Resistors
3) power Supply current trips
4) Operator Awareness
2 kV / few mA
To Scintillators
Potential
Electric shock
Risk
Operator, others
in clean room
Mechanical
handling, heavy
parts, Flange
Removal
Dropping Risk
Operator, others
in clean room
Electronics
Data acquisition
Trailing ad hoc
cables, trip
hazard
Operator, others
in clean room
Result
(13)
A
Medium hazard,
Layered Protection
Low Risk
A
1) Standard Sealed Devices no reason to
Disassemble
Low risk
A
1) Big Vessels permanently on own trolleys
2) 2 people to undo large Vac flanges
use Removal frame + Hydraulic lift truck
Low Risk
A
Low Risk
A
1) Use cable trays /cable bridges
2) Operator training
Generally watch that additions and alterations are properly engineered, avoid ad hoc supports, trailing cables etc.
Use cable trays.Action to shut down in Emergency
Power: Isolate mains to entire clean room at Distribution Panel in Entrance Lobby
OR isolate Mains to Gas rack (mains socket is behind gas rack)
Gas: Isolating power will stop gas flow to bubbler and detectors
Isolate gas cylinders at Cylinder Valves