~E~EI3 ~IULWLiL EP~fl3TD4-1D Natural analogues to the conditions around a final repository for high-level radioactive waste Proceedings of the natural analogue workshop held at Lake Geneva, Wisconsin, U.S.A. (october 1-3,1984) John A.T. Smellie (Editor) Swedish Geological Company Uppsala, Sweden December 1984 SVENSK KARNBRANSLEFORSORJNING AB/AVDELNING KBS Swedish Nuclear Fuel Supply Co/Division KBS MAILING ADDRESS: SKBF/KBS, Box 5864, S-102 48 Stockholm, Sweden Telephone: 08-67 95 40 NATURAL ANALOGUES TO THE CONDITIONS AROUND A FINAL REPOSITORY FOR HIGH-LEVEL RADIOACTIVE WASTE PROCEEDINGS OF THE NATURAL ANALOGUE WORKSHOP HELD AT LAKE GENEVA, WISCONSIN, U.S.A. (OCTOBER 1-3, 1984) John A.T. Smellie (Editor) Swedish Geological Company Uppsala, Sweden This report concerns a study which was conducted for SKB. The conclusions and viewpoints presented in the report are those of the author(s) and do not necessarily coincide with those of the client. A list of other reports published in this series during 1985 is attached at the end of this report. Information on KBS technical re.?rts ffom 1977-1978 (TR 121), 1979 (TR 79-28), 1980 (TR 80-26),. 1981 (TR 81-17), 1982 (TR 82-28), 1983 (TR 83-77) and 1984 (TR 85-01) is available through SKB. NATURAL ANALOGUES TO THE CONDITIONS AROUND A FINAL REPOSITORY FOR HIGH-LEVEL RADIOACTIVE WASTE PROCEEDINGS OF THE NATURAL ANALOGUE WORKSHOP HELD AT LAKE GENEVA, WISCONSIN, U.S.A. (OCTOBER 1-3, 1984) John A.T. Smellie (Editor) Swedish Geological Company, Box 1424, 751 44 Uppsala The Workshop was co-sponsored by the Swedish Nuclear Fuel and Warte Management Company (SKB) and the U.S. Department of Ener- gy, Chicago Operations Office, Crystalline Repository Project Of- fice, Argonne, Illinois. ABSTRACT This report documents the proceedings resulting from a Workshop held at Lake Geneva, Wisconsin, USA, from 1-3 October, 1984. The theme of the Workshop was entitled "Natural analogues to the con- ditions around a final repository for high-level radioactive waste", and was restricted to ultimate disposal in a crystalline bedrock environment. The Workshop provided an important first step in co-ordinating and focussing different national and indi- vidual interests and approaches towards natural analogue studi- es. One of the points highlighted at the concluding forum of the meet- ing was the necessity to first define the geochemical processes which are assumed to occur after disposal of the radioactive waste, and then locate suitable analogue systems which can be used to test the mechanisms of one, or a simple combination of these geochemical processes. Even accepting that the choice of which geochemical process(es) to be selected for validation will be sensitive to individual national disposal strategies, far- field radionuclide retardation mechanisms in the geosphere were considered to be a central topic of importance, and should there- fore be given high priority. At this early stage in the development of natural analogue studi- es it was not possible to cover all the important aspects. In re- trospect, the role of the modelles should'have received more at- tention; bridging the gap between geoscientists and the modellers was seen as being of prime importance in future meetings of this nature. i CONTENTS Page nr I INTRODUCTION AND SUMMARY OF THE WORKSHOP I:1 (N.A. Chapman and J.A.T. Smellie) SESSION A: ANALOGUES AND PROCESSES (Chairman: Douglas G. Brookings) Al THE POTENTIAL OF NATURAL ANALOGUES IN ASSESSING Al: I SYSTEMS FOR DEEP DISPOSAL OF HIGH-LEVEL RADIO- ACTIVE WASTE N.A. Chapman, I.G. McKinley and J.A.T. Smellie A2 SOME USES FOR NATURAL ANALOGUES IN ASSESSING A2: 1 THE FUNCTION OF A HLW REPOSITORY I. Neretnieks A3 GEOCHEMICAL ANALOGUES OF HIGH-LEVEL RADIOACTIVE A3:I WASTE REPOSITORIES P.L. Airey and M. Ivanovich A4 NATURAL ANALOGUES TO NUCLEAR FUEL WASTE DISPOSAL A4:1 IN CRYSTALLINE ROCKS: AN OVERVIEW J.J. Cramer A5 NATURAL ANALOGUES AND VALIDATION OF PERFORMANCE A5:1 ASSESSMENT MODELS N.A. Eisenberg ii Page SESSION B: SOME APPLICATIONS OF ISOTOPIC METHODS TO HIGH-LEVEL RADIOACTIVE WASTE (Chairman: David B. Curtis) Bl EVALUATION OF LONG-TERM AND SHORT-TERM INTEGRITY BI :1 OF CRYSTALLINE ROCKS BASED PRIMARILY ON URANIUM SYSTEMATICS J.N. Rosholt, R.A. Zielinski and Z.A. Peterman B2 APPLICATIONS OF U-Th-Pb ISOTOPIC SYSTEMATICS TO B2: 1 THE PROBLEMS OF RADIOACTIVE WASTE DISPOSAL J.S. Stuckless SESSION C: MORRO DO FERRO ANALOGUE (Chairman: Peter L. Airey) C1 NATURAL ANALOGUES FOR THE TRANSURANIC ACTINIDE C1:1 ELEMENTS: AN INVESTIGATION IN MINAS GERAIS, BRAZIL M. Eisenbud, K. Krauskopf, E. Penna Franca, W. Lei, R. Ballard, P. Linsalata and K. Fujimori C2 THORIUM AS AN ANALOGUE FOR PLUTONIUM AND RARE-EARTH C2: 1 METALS AS ANALOGUES FOR HEAVIER ACTINIDES K.B. Krauskopf C3 RADIUM MOBILIZATION AND TRANSPORT AT A LARGE THORIUM C3: 1 ORE DEPOSIT IN BRAZIL E. Penna Franca, M.T. Campos, N. Lobao, H. Trindade, I. Sachett and A. Eisenbud C4 DISTRIBUTION AND MOBILIZATION OF CERIUM, LANTHANUM C4: 1 AND NEODYMIUM IN TT1E MORRO DO FERRO BASIN. BRAZIL W. Lei, P. Linsalata, E. Penna Franca and M. Eisenbud iii Page C5 NATURAL ANALOGUE STUDIES: GEOLOGY AND MINERALOGY C5:1 OF MORRO DO FERRO, BRAZIL P.M.C. Barretto and K. Fujimori SESSION D: URANIUM DEPOSITS AS NATURAL ANALOGUES (Chairman: Harold Wollenberg) DI RADIONUCLIDE MIGRATION AROUND URANIUM ORE DI: 1 BODIES IN THE ALLIGATOR RIVERS REGION OF THE NORTHERN TERRITORY OF AUSTRALIA - ANALOGUE OF RADIOACTIVE WASTE REPOSITORIES P.L. Airey D2 SANDSTONE-HOSTED URANIUM DEPOSITS IN NORTHERN D2: 1 SASKATCHEWAN AS NATURAL ANALOGUES TO NUCLEAR FUEL WASTE DISPOSAL VAULTS J.J. Cramer D3 GEOCHEMICAL CONTROLS ON 9 9 Tc TRANSPORT AND D3 :1 RETENTION D.B. Curtis D4 AN ANALOGUE VALIDATION STUDY OF NATURAL RADIO- D4 :1 NUCLIDE MIGRATION IN CRYSTALLINE ROCKS USING URANIUM SERIES DISEQUILIBRIUM STUDIES J.A.T. Smellie, A.B. MacKenzie and R.D. Scott D5 THE MARYSVALE NATURAL ANALOGUE. STUDY: PRELIMINARY D5:1 OXYGEN ISOTOPE RELATIONS M.E. Shea and K.A. Foland iv Page SESSION E: HYDROTHERMAL/GEOTHERMAL ANALOGUE SYSTEMS (Chairman: Jan J. Cramer) El CONTACT ZONES AND HYDROTHERMAL SYSTEMS AS ANALOGUES El :1 TO REPOSITORY CONDITIONS H.A. Wollenberg and S. Flexser E2 NATURAL ANALOGUES FOR RADWASTE DISPOSAL: ELEMENTAL E2: 1 MIGRATION IN IGNEOUS CONTACT ZONES D.G. Brookins E3 INVESTIGATIONS OF THE EMPIRE CREEK STOCK, MONTANA, E3: 1 AS A POSSIBLE ANALOGUE TO A NUCLEAR WASTE REPOSI- TORY H.Y. Tammemagi and B. Haverslew SESSION F: ANALOGUES OF LOW TEMPERATURE RADIO- NUCLIDE MIGRATION AND SORPTION (Chairman: John S. Stuckless) F1 THE DISTRIBUTION OF URANIUM, THORIUM AND RARE F1:I EARTH ELEMENTS IN GRANITIC ROCKS - A STUDY OF SOME ANALOGUE ELEMENTS D.C. Kamineni F2 A NATURAL ANALOGUE STUDY OF LONG-TERM (103 - 104 a) F2: 1 RADIONUCLIDE MIGRATION IN SATURATED SEDIMENTS FROM LOCH LOMOND, SCOTLAND A.B. MacKenzie, I.M. Ridgway, R.D. Scott, P.J. Hooker, J.M. West and I.G. McKinley 1:1 INTRODUCTION AND SUMMARY OF THE WORKSHOP INTRODUCTION The central issue in assessing the long-term performance and safety of a radioactive waste disposal facility is the ability to predict confidently the nature and effect of processes and geolo- gical events far into the future. Assessment models which are de- terministic require evidence that the processes which they consi- der will actually occur at the predicted magnitudes and time scale. Probabalistic models require evidence that events will or will not occur, and with what likelihood. The time-scale over which these predictions are made depends on the wastes and disposal concept involved, but may vary from a few hundred years to several hundreds of thousands of years. In any case the obvious problem is in extrapolating laboratory data, generally obtained over months or at most a few years, out to realistic times into the future. The processes being studied in the laboratory consider specific aspects of the mobilisation of radionuclides from the waste and their subsequent transport in groundwaters. Fortunately almost all of the processes of interest are also to be found operating in the natural environment, although different elements and dif- ferent geochemical and hydrochemical regimes may be involved. There is thus an opportunity to use natural analogues to assess these processes over geological time scales. To be useful a natural analogue must be tightly constrained to a particular process, with the boundary conditions well defined. Analogues of a complete disposal system do not exist. Even in the case of the nearest approach (fossil reactors) the boundary conditions are significantly different or unknown, and the analo- gue cannot be used as a large scale and wide-ranging control on a rigorously modelled dose calculation. In order to provide eit- her validation or benchmarks the analogue must be tied to a par- ticular process critical to the overall model. The role of a na- tural analogue should thus be to confirm: a) that the process is in fact something which can or will occur in practice as well as in theory, and in nature as well as in the laboratory b). --here, when, and under what conditions it can occur c) that the effects of the process are those envisaged in the model I:2 d) that the magnitude of the effects in terms of scale and time are similar to those predicted for a similar set of condi- tions All of the processes of interest are essentially chemical or phy- sico-chemical in nature, and consequently the analogues to seek lie in natural geochemical systems. Suitable conditions are most commonly encountered in ore depo- sits (either pre-existing or in the process of formation) and not surprisingly these provide the most accessible and useful analogues.