Disposal of Radioactive Waste in Granitic Bedrock - ACS Symposium

4 Disposal of Radioactive Waste in Granitic Bedrock 1

B. ALLARD , J. RYDBERG, H . KIPATSI, and B. TORSTENFELT

Downloaded by RUTGERS UNIV on December 26, 2017 | http://pubs.acs.org Publication Date: April 6, 1979 | doi: 10.1021/bk-1979-0100.ch004

D e p a r t m e n t of N u c l e a r C h e m i s t r y , C h a l m e r s U n i v e r s i t y of T e c h n o l o g y , F a c k , S-402 20 G ö t e b o r g 5, S w e d e n

A requirement, as stated in a recent Swedish law, for a continuation of the extensive nuclear power program in Sweden (6 operating power reactors at present and 7 more in operation in 1985) is that the engineering problems and safety aspects connected with the disposal of the high-level waste (HLW) or the unreprocessed spent uranium fuel (SUF) are thouroughly investigated. A completely safe disposal of either HLW or SUF must be guaranteed and technically proven by the nuclear power industry. The Nuclear Fuel Safety Project (Kärnbränslesäkerhet, KBS) was started in December 1976 with the purpose of studying a l l important aspects of waste disposal in Sweden. Two different alternatives for final storage of HLW and SUF, respectively, have so far been suggested and studied in detail by KBS (1). Some data for these two concepts are given in Table I and in Figure 1. For both alternatives a storage in granitic bedrock at a depth of 500 m is considered. This is well below the groundwater table. The waste canisters will be placed in vertical holes in horizontal tunnels and both holes and tunnels will be filled with a backfill material (c.f. Figure 1). In this paper some of the chemical aspects of such a waste storage in granitic bedrock are discussed (2-7). The Multi-Barrier Principle For a repository in the ground there are several independent barriers between the waste and the biosphere, such as - long-term geological s t a b i l i t y and very limited groundwater flow at the selected site - resistant canister material - waste form with low solubility - backfill material with nuclide retaining properties - chemical retention in the ground. Current address: Transuranium Research Laboratory, Oak Ridge National Laboratory, P. O . Box X , Oak Ridge, Tenn. 37830, U S A . 1

© 1979 American Chemical Society

Fried; Radioactive Waste in Geologic Storage ACS Symposium Series; American Chemical Society: Washington, DC, 1979.


RADIOACTIVE WASTE IN GEOLOGIC STORAGE

QUARTZ SAND 80-90% BENTONΠΈ Κ)-20% (TUNNEL)

QUARTZ SAND 85% BENTON ITE 15%

TITANIUM, 6mm LEAD, 100 mm STEEL 13 mm GLASS WASTE (HLW) LEAD QUARTZ SAND 90% BENTON ITE 10% TITANIUM CAP 1000

Figure la.

NOTE: DIMENSIONS ARE IN mm

Storage of HLW in the ground (KBS) (1 )


ALLARD ET AL.

Radioactive

Waste

Disposai


4.

Figure lh.

Storage of SUF in the ground (KBS) (l)


49

50

RADIOACTIVE WASTE IN GEOLOGIC STORAGE

Table I Some data for the two concepts for storage of HLW and SUF as suggested by KBS ( j j


Canister property

Reprocessed v i t r i f i e d HLW

Unreprocessed SUF

Equivalent waste amount

From 1 ton SUF

Central part composition

420 kg borosilicate glass with 9% FP

Central part weight Outer canning Total canister: Dimensions Weight Canister surface temp: Max After 1000 y a

Bentonite backfill (outer barrier) Rock hole dimensions

1.3 ton SUF

b

C

550 fuel pins + lead in voids

450 kg, i n c l . 3 mm 2 ton fuel stainl.steel cladding + 2.5 ton lead 100 mm lead + 6 mm titanium

200 mm copper

0.6-1.8 m 3.9 ton

0.8-4.7 m 20 ton

65°C 35°C

77°C 50°C

0.2 m

0.4 m

1.0-5.0 m

1.5-7.7 m

?At 33,000 MWd/ton U burn-up 38 kg fissions products (FP),

Disposal of Radioactive Waste in Granitic Bedrock - ACS Symposium

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