Risk Assessment can be quite straighforward and doesn't necessarily need heaps of documentation. The main thing is to document it so that you can prove you acted reasonably (should an accident occur!). There's no law that lays down the method so here is one way to skin this particular cat:
Make a list of the hazards. Could include fire, explosion, burns, entrapment of body parts, crushing, etc.
For each hazard:
- Decide the potential harm on some scale. Typically you could use abstract values of intensity (low/medium/high) or numeric scale (say 1 to 5).
- Decide the possibility (chance) of it occurring. Again, can be low/medium/high or a numeric scale.
Now multiply the numbers or use a matrix for the abstract values to reach an overall risk level. If you are working in numbers the result might be in the range 1 to 25. In abstracts it could be insignificant/very low/low/medium/high/very high, etc.
Now decide what (if anything) you need to do. This stage is called 'control measures'. If the result was insignificant or a low number, you might say 'no further action'. If it is medium level you probably need to do something. If it is high/very high, you'll definiely need to do something.
If you need to take action, you select one or more control measures from a hierarchical list. The acronym ERICPD is commonly used. Start at the top and work down until you reach a practicable solution. Here's some idea how this works, using 'road traffic accident' as the hazard.
E = Eliminate - turn the road into a pedestrianised area.
R = Reduce - Introduce a speed limit. Might still be a collision but death is less likely.
I = Isolate - Use barriers, subways, pedestrian bridges, etc. to ensure separation/isolation.
C = Control - Traffic lights.
P = Personal Protective Equipment - Pedestrians wear something light/bright, motorists wear seatbelts, cyclists wear helmets.
D = Discipline - Education, training (driver training, cycling proficiency) and we all learned to look both ways before crossing didn't we?
I spend a lot of time telling people not to go straight for PPE or discipline - start at the top. Remember it's a hierarchy.
Last step: Re-run the assessment of overall risk to check that your control measures have (or will) indeed reduced the risk.
Make sure all this is documented.
Job done (though you should also review periodically)
There is more information on the websites of HSE, IOSH and NEBOSH.