STUDI EKSPERIMEN DIFUSI BORON DALAM BENTONIT TERKOMPAKSI DALAM KONDISI REDUKSI OLEH FE

ABSTRACT
EXPERIMENTAL STUDY ON BORON DIFFUSION IN COMPACTED BENTONITE UNDER REDUCING
CONDITION WITH IRON. After the previous Fukushima-Daiichi power plant accident, it generated radioactive
wasteand around the radioactive waste will begiven to disposal covered with bentonite.There is a large amount of
boron in the waste, may have an impact on the environment that boron is to migrate through the bentonite. The other
hand vitrified wastefor high-level waste will be encapsuled into carbon steel overpack then disposed with bentonite in
deep underground.After a long period of time elapsed, the fact that groundwater is in contact with the vitrified corrode
carbon steel, boron that was used in the glass solidification it considered that there is a possibility to migrate through
the bentonite. Electromigration experiment was doing for understand the diffusion behavior of boron in bentonite.
Electromigration experiments have been carried out with source of iron. Iron supplied by anode corrosion of iron
coupon. A small amount of tracer solution (boric acid and tetra-borate) was uniformly pippeted on an end surface of
bentonite. The carbon steel coupon was assemblied with water saturated bentonite as anode then supplied electric
potential. After migration and diffusion period the bentonite specimen was sliced in the step of 0.5 to 2 mm. The
concentration of boron in each slice can be measured with inductively couple plasma-mass spectrometry (ICP-MS;
Agilent, 7500C). It was obtained apparent diffusion coefficient (Da) of boron in boric acid is 8.43 x 10-11 (m2/s), and
tetraborate acid is 1.61 x 10-11 (m2/s).t
Keywords : bentonite, Diffusion coefficient, electromigration