Download Risk_Assessment_MICE_fields

STFC QUANTITATIVE RISK ASSESSMENT PRO-FORMA
Ref:
Description: Danger due to the magnetic fields of the MICE magnets
Assessment Date: 14/06/16
Location/Site: MICE Hall and immediate neighbourhood
Assessor: Josef Boehm
Department:
Assessment Team::
Persons Exposed: Any user and visitor of the MICE facility
Activity/Task: Analyse the magnetic fields present in the MICE Hall, assess the potential exposure of people and machinery, assess the potential damage to people and machinery,
evaluate necessity of removal of magnetic fields
Step 1
What are the hazards?
Step 2
Who might be harmed What are you already What is the level of risk?
and how?
doing?
H
Hazard/Task or Situation
L
R
Harm
Likelihood
Risk
Person being trapped
in bore of magnet
Anyone accessing the
bores of the magnets
Bores are blocked by
instrumentation
and
being part of beamline.
Access to hall restricted
during
magnet
operation
High
Very
unlikely
medi
um
Person being trapped
on outer shell of
magnets, possibly only
parts of the body
Anyone working around
the
magnets
when
energised
Hall has limited access
when magnets are live,
access to top of magnet
is
restricted
or
forbidden,
magnetic
fields on surface are
low (typically around
1000G, localised hotspots of close to
5000G, these could
trap hands between
ferromagnetic tools for
instance). Fast rampdown
buttons
solenoids:
~20min,
focus coils: ~ 2h
mode
rate
Very
unlikely
low
Step 3:
What further
necessary?
action
Step 4:
is How will you put the Assessment into
action?
Action by
whom
By when
Done
QRA_r3.1_Nov_14
STFC QUANTITATIVE RISK ASSESSMENT PRO-FORMA
Person being exposed
to projectiles caused
by magnetic attraction
Danger to health of
person working near
surface of magnets
Magnetic fields outside
PRY too low to allow
projectiles, access to
top
of
magnets
restricted or forbidden,
range of fields that
could allow projectiles
is short (about 400mm).
The magnetic
field
where detectable forces
on
ferromagnetic
objects
appear
is
approximately 100G.
mode
rate
unlikely
medi
um
Person being exposed
to quench gases of
superconducting
magnets
Danger to health of
person, possibly even
fatal
Access to quench ports
is
blocked
during
operation, access to top
of magnets restricted
while magnets are live
high
Very
unlikely
medi
um
Person being injured
by cold quench gases
Person standing in front
of quench port
Quench
should
marked
exit
ports
be
clearly
high
Very
unlikely
medi
um
Warning labels to be fitted
to quench outlets
Anyone working at the
top of the magnets
Access to top of
magnets restricted to
experienced
staff,
banisters are around
access
platforms,
suitable
walkways
should be installed
beyond
accessible
access areas
high
Very
unlikely
medi
um
Screens to be fitted near
walkways at the top of the
magnet
Person falling between
magnet skin and PRY
QRA_r3.1_Nov_14
STFC QUANTITATIVE RISK ASSESSMENT PRO-FORMA
Danger
to
people
entering areas of high
magnetic field (with
cardiac pace-makers
or brain implants).
Unless there is very
close proximity to OVC
(mainly of the FC) a
risk to magnetic media
(eg credit cards) is
very low.
Anyone entering the
MICE
hall
during
magnet operation
Hall has limited access
when magnets are live.
The limit of 5G needs to
be
clearly
visible.
Warning labels of high
magnetic field exposure
need to be prominently
visible. The 5G line will
have to be re-measured
each time a new
magnet configuration is
applied as the stray
field
from
these
magnets will change.
Distribution List:
If the risk is significant, has it been entered into
the SHE enterprise database?
Step 5 Review Date:
high
Very
unlikely
medi
um
Signed:
Yes



No

Field outlines are clearly
outlined, will need to be reconfirmed for alternative
magnet arrangements
Date:
SHE enterprise ref no:
Review your assessment to make sure you are still improving, or at least not sliding back.
If there is a significant change in your workplace, remember to check your risk assessment and where necessary, amend it.
QRA_r3.1_Nov_14
STFC QUANTITATIVE RISK ASSESSMENT PRO-FORMA
Description of magnet coils:
Focus coils:
Properties: Lmax 111H, max ramp-rate: 7V, max I: 220A, normal ramp-down time ~1h
Max field in bore: 4T, field at side of OVC: ~0.5T, field at C/H: < 0.2T
Bore always enclosed, magnet within iron shield, access to top possible but usually not allowed
Biggest stray field in flip mode (220A)
Solenoid coils:
Properties: Lmax 85H, max ramp rate: 4V, max I: 280A, normal ramp-down time ~ 1.5h
Max field in bore: 4T, field on side of OVC: < 0.2T, field at cold heads < 0.1T
Bore always enclosed, magnet within iron shield, access to top possible but usually not allowed
Decay magnet (solenoid):
Superconducting magnet, bore blocked during operation, magnet is internally shielded, stray field very low
Quadrupole and Dipole magnets:
Conventional conductors, shielded housing, bore blocked and inaccessible during operation, stray field minimal
Extent of 5G line
QRA_r3.1_Nov_14
STFC QUANTITATIVE RISK ASSESSMENT PRO-FORMA
0
1000mm
ZX plane, horizontal, PRY shown
0mm
1000mm
2000mm
Magnetic field profile on skin of magnets (red
line)
ZY plane, vertical, no PRY at top
Plots by H Witte in ZX (through wall of PRY) and ZY planes (towards
ceiling). Red line indicates outer skin of OVC (at 700mm). Maximal
possible field exposure to 0.5T at section between FC and Solenoid.
Lower end is end plate of PRY.
Flux densities are shown in Tesla. In other
units: 100G, 1000G, 2000G … 10,000G. The red
or brown intensities are closer to the centre
of the magnet, the dark-blue intensities are
away from the magnet.
Due to low gradient of the exposed field the magnetic attraction is
limited, even at the highest field areas. A hammer would be attracted
to the skin of the magnet with a force of approximately 20kg.
QRA_r3.1_Nov_14
STFC QUANTITATIVE RISK ASSESSMENT PRO-FORMA
LEVEL OF RISK
There will be some instances where you may need to assign priorities to actions from an
assessment or you may be responsible for managing the actions from a number of assessments.
In either case you will need a coherent method for assigning a priority to actions. This Quantitative
Risk Assessment pro-forma gives you this option.
There are three additional fields available when entering or editing any task in an assessment:



Harm,
Likelihood and
Risk.
For each hazard, you choose options for the Harm and Likelihood categories.
Use the information contained in Step 2, categorise the harm that might be caused:
As a general rule you are looking for ‘the most likely reasonably foreseeable injury’ not just the
worst case.
Decide How Someone Might be Harmed
Major
Fatality.
High
Amputations; multiple serious injuries; major fractures; major burns.
Moderate
Lacerations; burns; concussion; serious sprains; minor fractures.
Slight
Superficial injuries; minor cuts and bruises; eye irritation from dust.
Below are the phrases that are used in the risk database to describe the likelihood of something
happening and how someone might be harmed:
How Likely is it to Happen?
Very Unlikely
The hazard is very rarely experienced and exposure will seldom result in
injury.
Unlikely
The hazard is rarely experienced and exposure will seldom result in
injury.
Likely
The hazard is persistent but exposure may not always result in injury.
Very Likely
The hazard is persistent and exposure will undoubtedly result in injury.
Then use the matrix below to obtain a ‘risk factor’ from the likelihood and harm categories for each
hazard (e.g. if you decided the harm category was ‘moderate’ and the likelihood was ‘unlikely’ the
risk factor would be ‘medium’). This risk category is then used to determine what priority should be
given to reducing the risk factor for that particular hazard.
STFC QUANTITATIVE RISK ASSESSMENT PRO-FORMA
Risk Factor
Harm
To manually calculate the risk factors use the table below:
Major
High
High
V High
V High
High
Med
Med
High
V High
Moderate
Low
Med
Med
Med
Slight
Low
Low
Low
Low
Very Unlikely
Unlikely
Likely
Very Likely
Likelihood
Low Risk - No additional controls are necessary unless they can be
implemented at very low cost (in terms of time, money and effort).
Actions to further reduce these risks can be assigned low priority.
Medium Risk - Consideration should be given as to whether the risks can
be lowered, where applicable, to a low risk level, but the costs of
additional risk reduction measures should be take into account. The risk
reduction measures should be implemented within a defined time period.
High Risk – Substantial efforts should be made to reduce the risk. Risk
reduction measures should be implemented urgently within a defined
time period and it might be necessary to consider suspending or
restricting the activity, or to apply interim control measures, until this has
been completed. Considerable resources might have to be allocated to
additional control measures.
V High Risk - These risks are unacceptable. Substantial improvements in
risk controls are necessary. The work activity should be halted until risk
controls are implemented. If it is not possible to reduce risk the work
should remain prohibited.