scholarly journals Waste Isolation Pilot Plant Materials Interface Interactions Test: Papers presented at the Commission of European Communities workshop on in situ testing of radioactive waste forms and engineered barriers

1993 ◽  
Author(s):  
M.A. Molecke ◽  
N.R. Sorensen ◽  
G.G. Wicks
Keyword(s):  
Radioactive Waste ◽  
Pilot Plant ◽  
In Situ Testing ◽  
Plant Materials ◽  
Waste Isolation Pilot Plant ◽  
Waste Forms ◽  
Engineered Barriers

Methodology in Corrosion Testing of Container Materials for Radioactive Waste Disposal in a Geological Clay Repository

2001 ◽  
Author(s):  
Bruno Kursten ◽  
Frank Druyts ◽  
Pierre Van Iseghem
Keyword(s):  
Radioactive Waste ◽  
Corrosion Behaviour ◽  
Open Circuit ◽  
Geological Disposal ◽  
Boom Clay ◽  
Engineered Barriers ◽  
High Level ◽  
Aerobic And Anaerobic

Abstract The current worldwide trend for the final disposal of conditioned high-level, medium-level and long-lived alpha-bearing radioactive waste focuses on deep geological disposal. During the geological disposal, the isolation between the radioactive waste and the environment (biosphere) is realised by the multibarrier principle, which is based on the complementary nature of the various natural and engineered barriers. One of the main engineered barriers is the metallic container (overpack) that encloses the conditioned waste. In Belgium, the Boom Clay sediment is being studied as a potential host rock formation for the final disposal of conditioned high-level radioactive waste (HLW) and spent fuel. Since the mid 1980’s, SCK•CEN has developed an extensive research programme aimed at evaluating the suitability of a wide variety of metallic materials as candidate overpack material for the disposal of HLW. A multiple experimental approach is applied consisting of i) in situ corrosion experiments, ii) electrochemical experiments (cyclic potentiodynamic polarisation measurements and monitoring the evolution of ECORR as a function of time), and iii) immersion experiments. The in situ corrosion experiments were performed in the underground research facility, the High Activity Disposal Experimental Site, or HADES, located in the Boom clay layer at a depth of 225 metres below ground level. These experiments aimed at predicting the long-term corrosion behaviour of various candidate container materials. It was believed that this could be realised by investigating the medium-term interactions between the container materials and the host formation. These experiments resulted in a change of reasoning at the national authorities concerning the choice of over-pack material from the corrosion-allowance material carbon steel towards corrosion-resistant materials such as stainless steels. The main arguments being the severe pitting corrosion during the aerobic period and the large amount of hydrogen gas generated during the subsequent anaerobic period. The in situ corrosion experiments however, did not allow to unequivocally quantify the corrosion of the various investigated candidate overpack materials. The main shortcoming was that they did not allow to experimentally separate the aerobic and anaerobic phase. This resulted in the elaboration of a new laboratory programme. Electrochemical corrosion experiments were designed to investigate the effect of a wide variety of parameters on the localised corrosion behaviour of candidate overpack materials: temperature, SO42−, Cl−, S2O32−, oxygen content (aerobic - anaerobic),… Three characteristic potentials can be derived from the cyclic potentiodynamic polarisation (CPP) curves: i) the open circuit potential, OCP, ii) the critical potential for pit nucleation, ENP, and iii) the protection potential, EPP. Monitoring the open circuit potential as a function of time in clay slurries, representative for the underground environment, provides us with a more reliable value for the corrosion potential, ECORR, under disposal conditions. The long-term corrosion behaviour of the candidate overpack materials can be established by comparing the value of ECORR relative to ENP and EPP (determined from the CPP-curves). The immersion tests were developed to complement the in situ experiments. These experiments aimed at determining the corrosion rate and to identify the corrosion processes that can occur during the aerobic and anaerobic period of the geological disposal. Also, some experiments were elaborated to study the effect of graphite on the corrosion behaviour of the candidate overpack materials.

scholarly journals The Advantages of a Salt/Bentonite Backfill for Waste Isolation Pilot Plant Disposal Rooms

1993 ◽  
Vol 333 ◽  
Author(s):  
B.M. Butcher
Keyword(s):  
Radioactive Waste ◽  
Pilot Plant ◽  
Selection Criteria ◽  
Final State ◽  
Government Regulations ◽  
Waste Isolation Pilot Plant ◽  
40 Cfr 191 ◽  
Backfill Materials ◽  
The Impact ◽  
Sorption Potential

ABSTRACTThis paper concludes that a 70 wt% salt/30 wt% bentonite mixture is preferable to pure crushed salt as backfill for disposal rooms in the Waste Isolation Pilot Plant. The performance of two backfill materials is examined with regard to various selection criteria related to compliance with the transuranic radioactive waste standard 40 CFR 191, Subpart B, such as the need for low liquid permeability after closure, chemical stability, strength, ease of emplacement, and sorption potential for brine and radionuclides. Both salt and salt/bentonite are expected to consolidate to a final state of permeability ≤ 10-18 m2, which is adequate for satisfying government regulations for nuclear repositories. The real advantage of the salt/bentonite backfill depends, therefore, on bentonite’s potential for sorbing brine and radionuclides. Estimates of the impact of these properties on backfill performance are presented.

scholarly journals Instrumentation of the thermal/structural interactions in situ tests at the Waste Isolation Pilot Plant (WIPP)

1997 ◽  
Author(s):  
D.E. Munson ◽  
D.L. Hoag ◽  
D.A. Blankenship ◽  
W.F. DeYonge ◽  
D.M. Schiermeister ◽  
...  
Keyword(s):  
Pilot Plant ◽  
In Situ Tests ◽  
Waste Isolation Pilot Plant ◽  
Structural Interactions
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