Rudarski radovi br 4 2011 - Institut za rudarstvo i metalurgiju Bor

will occur from exposure to hazard and to<br />
assess the severity of such effects. However,<br />
assessment also includes accompanying<br />
criteria, such as frequency of occurrence<br />
and duration of exposure to hazard,<br />
as well as likelihood of avoiding adverse<br />
effects.<br />
In the risk assessment, it is necessary to<br />
determine whether hazard can manifest<br />
itself in conditions without errors, with one<br />
error and with several errors. Hazards with<br />
severe effects can not be tolerated under<br />
any circumstances.<br />
The following classification is in accordance<br />
with the IEC 60601-1-4 Standard.<br />
It defines six degrees of likelihood<br />
of occurrence of adverse effect, from lowest<br />
to highest.<br />
- very unlikely<br />
- unlikely<br />
- seldom<br />
- occasional<br />
Table 2.[7]<br />
- likely<br />
- frequent.<br />
Four degrees of severity of adverse effect<br />
are also defined:<br />
- catastrophic – several fatalities and<br />
serious injuries<br />
- critical – one or few fatalities and serious<br />
injuries<br />
- marginal – possible injuries<br />
- negligible – possible mild or no injuries.<br />
Table 2 shows a simple way of combining<br />
these criteria. This is a widespread<br />
approach, due to its simplicity and the fact<br />
that it is included in the International<br />
Standard.[6] However, a professional usage<br />
of this approach is not limited to the<br />
definitions given above and it can change,<br />
expand or shorten them in order to achieve<br />
the optimum classification in the case it<br />
works on.<br />
Degree of probability Degree of severity<br />
A- very unlikely<br />
B- unlikely<br />
C- seldom<br />
D- occasional<br />
E- likely<br />
F- frequent<br />
The above classification was applied<br />
to incidents that occurred at Kakanj Coal<br />
Mine in the last 16 years. According to the<br />
degree of probability, they can be classified<br />
as follows:<br />
- A – Very unlikely – Wide range explosion<br />
(not happened in the observed<br />
period)<br />
- B – Unlikely – Limited explosion<br />
(not happened in the observed period)<br />
- C – Seldom – Closure of longwall<br />
face (11), cavities(7)<br />
- D – Occasional – Occurrence of other<br />
gases (15), occurrence of CO (13)<br />
I II III IV<br />
Negligible Marginal Critical Catastrophic<br />
IV-A III-A II-A I-A<br />
IV-B III-B II-B I-B<br />
IV-C III-C II-C I-C<br />
IV-D III-D II-D I-D<br />
IV-E III-E II-E I-E<br />
IV-F III-F II-F I-F<br />
- E – Likely – Penetrations (35), other<br />
(32)<br />
- F – Frequent – Fire (41)<br />
According to the degree of severity,<br />
the recorded incidents can be classified as<br />
follows:<br />
- I – Catastrophic – In the observed<br />
period, cavities (7) and closure of<br />
longwall face (11), produced most<br />
fatalities (it can be assumed that<br />
wide range and limited explosions<br />
would produce the same consequences.)<br />
No 4, 2011. 125<br />
MINING ENGINEERING