DETERMINATION OF NUCLEAR POWER PLANT SITE IN WEST BANGKA BASED ON ROCK MASS RATING AND GEOLOGICAL STRENGTH INDEX

Abstract

Indonesian government through the National
Atomic Energy Agency has planned to build a
nuclear power plant. One of the proposed sites
is in West Bangka Regency, Bangka Belitung
Archipelago Province. The engineering geology
of this area is, however, not fully understood and
requires further investigations. Engineering geology investigations were carried out by assessing the
rock mass quality and bearing capacity based on
field observation and drilling data. The assessment
was conducted using Rock Mass Rating (RMR)
and Geological Strength Index (GSI) classifications.
The rock masses in the study area were divided
into four units, namely units of sandstone, granite,
mudstone and pebbly sandstone. The RMR and
GSI values in the study area were influenced by the
parameters of discontinuity space density, the slope
of discontinuity orientation, grade of weathering
and groundwater conditions. The assessment shows
that the granite unit had the best quality which was
shown by a 53 average RMR value and 66 GSI
value. Based on the average RMR value, the granite
unit was estimated to have cohesion value between
0.2 and 0.3 MPa, friction angle between 25° and
35°, and allowable bearing pressure between 280
and 135 T/m2. Based on the GSI value, the granite
unit was estimated to have uniaxial compressive
strength value between 1.0465 and 183.8 MPa, ten-sile strength between (-0.0122) and (-5.2625) MPa,
rock mass strength values between 24.5244 and
220.351 MPa, and modulus of deformation within
a range of 1.73 - 86.68 GPa. The Granite Unit was
considered to be the most appropriate location for
the nuclear power plants.