Risk level

Risk degree

Risk description

1

$R_i=0$

safe

2

$R_i\le {\epsilon }_1$

low

3

${\epsilon }_1<R_i\le {\epsilon }_2$

medium

4

${\epsilon }_2<R_i\le {\epsilon }_3$

serious

5

$R_i>{\epsilon }_3$

high