Research Coordination Meeting on CRP “Behaviour of Cementitious Materials in Long-Term

1. Research Coordination Meeting on CRP “Behaviour of Cementitious Materials in Long-Term Storage and Disposal of Radioactive Waste” (Romania, November 24-28, 2008) CEMENTATION OF CERTAN TYPES OF LIQUID RADIOACTIVE WASTE OF RADIOCHEMICAL PLANT L. Sukhanov. P. Poluektov, K. Zakharova, O. Khimtchenko, Yu.Matyunin A.A. Bochvar Research Institute of Inorganic Materials, Moscow

2. Individual project • of Leonid Sukhanov • (A.A.Bochvar Research Institute) • Subject: • Cementation of certain types of liquid ILW generated from SNF reprocessing at radiochemical combine PA Mayak, Urals • Cementation of pulps from storage tanks of the radiochemical combine MCC (Mining and Chemical Combine), Siberia

3. MAIN OBJECTIVES AND SCOPE OF INDIVIDUAL PROJECT • Studying processes that occur during production of the cement compounds generated during solidification ofsome kinds of liquid RW of radiochemical combines - PA Mayak, Urals and MCC, Siberia • Determining of cement compound characteristics (mechanical strength, water resistance, frost resistance,flowability, heat release, loading capacity of waste and others) • Giving recommendations for operation of a commercial facility for production of cement compounds satisfying waste acceptance criteria and national requirements • Assessing behaviour of the produced cement compounds during their storage

4. PLANNED INVESTIGATIONS FOR THE FIRST YEAR - -cementationofevaporatorconcentrates and pulps of PA Mayak Under this work, special emphasis will be given to: • cementation of salt solutions containing hydroxide sludge • production of high-flowable cement compounds • cementation of spent filter materials pulps • The researches were carried out using the equipment, • instruments, personnel and materials of A. A. BochvarResearch Institute.

5. Ammonia solution Acidic decontamination solution Acidic rafinate from extraction Concentrate from membrane-sorption LLW treatment Evaporation, Rectification Ammonia solution Nitric acid Evaporation bottom Condensate Re-evaporation Ion-exchange resin pulps Filter perlite pulps Purification Evaporator concentrate Manganese dioxide pulps Tritium containing waste Cementation Cement compound Long-term storage(disposal) PA Mayak’s liquid RW planning to send to cementation

6. SPECIFIC FEATURES OF PA MAYAK’S LIQUID ILW THAT HAVE EFFECT ON CEMENTATION PROCESS PARAMETERS • A variety of different types of liquid wastes, specifically: - salt alkaline waste (3 types) and acid waste (2 types) - liquid tritium waste - pulps of filter materials and hydroxides (4 types) • Certain components present in LRW can significantly influence the liquid ILW treatment scheme and, specifically, the cementation process and properties of a produced cement compound (iron hydrooxide, ammonia, nitric acid, tritium, etc.) • The cement compound will be stored not in drums or other containers, but in concrete compartments of a storage facility (the volume of each compartment is about 380 m3)

7. REQUIREMENTS FOR CEMENT COMPOUNDS AT PA MAYAK REMENTATION COMPLEX The produced cement compound quality must satisfy: TheNational Standards: • GOST R 51883-2002 “Cementitious Radioactive Waste. General Requirements“ • NP-019-2000 “Reguirements to liquid RW Management” Additional requirements: • sufficientflowability to ensure uniform filling of storage facility compartments • low heat release during the compound solidification in storage facility compartments • maximum loading capacity of a cement compound

9. RESEARCH METHODOLOGY • Sample Preparation • The cement paste made through mixing the components by using the laboratory-scale equipment is placed into the device designed for preparation of cement compound samples. • The device represents a dismountable cartridge (cassette) consisting of several cells (molds) to allow making cement cubes 2×2×2 cm in size. • The device is placed in a humid-air atmosphere in an exsiccator with water at the bottom to prevent desiccation (drying). • When held for 28 days, the samples were taken from the cells for further analyses. • Radionuclides used for RW simulation are Sr-90, Cs-137 and tritium.

10. RESEARCH METHODOLOGY • Matrix Materials • In most experiments a mixture of Portland cement (Grade PC500-D0) and bentonit was used as a matrix material. • The content of bentonit in the matrix material in all the experiments was 10 wt %. Bentonit, which was introduced from a cement compound being in contact with water, acted as a sorbent to reduce leachability of radionuclides, primarily Cs-137. • The Slag Portland cement, a mixture of Portland cement and metallurgical slag, was used in a number of experiments.

11. RESEARCH METHODOLOGY • Determination of Ultimate Compressive Strength • Ultimate compressive strength is determined by means of a hydraulic press using the standard procedure. • Cement PastePlasticity Test • Plasticity of a cement paste is characterized by degree of its flowability (spreadability) measured by the viscosimeter using the standard procedure. • Frost resistance • Frost resistance is determined by the procedure, which included 30 freezing/thawing cycles. • Immersion Tests • Water resistance is determined by comparison of the strength of the samples held in water for 90 days to the strength of the reference samples held in the air under room conditions. • Long-Term Leaching Tests of Cement Compounds • A degree of radionuclide fixation in a cement compound is determined by the rate of radionuclide leaching and by the activity that passed into a solution from a cement compound.

12. Measurement of Cement-Paste Flowability Molds for Preparation of Cement by Suttard’s Viscosimeter EXPERIMENTAL TECHNIQUES AND EQUIPMENT Compound Samples

13. Hydraulic Press for Testing of Cement-Compound Sample Strength EXPERIMENTAL TECHNIQUES AND EQUIPMENT

14. EXPERIMENTAL TECHNIQUES AND EQUIPMENT Apparatus for Determination of Cement Hydration Heat -,-Radiometer UMF-2000

15. EXPERIMENTAL TECHNIQUES AND EQUIPMENT Exiccator for Damp Curing of Cement Compound Samples

16. RESEARCH SUBJECT • The following solutions and pulps simulating different liquid RW of PA Mayak were under consideration: • salt solutions with iron hydrate sludge • filter-material pulps • mixture of hydrated-salt sludge and filter-material pulps

17. CEMENTATION OF HYDRATED-SALT SLUDGE Assessment of the effect of a compound composition on flowability of cement-paste and mechanical strength of a solid product

18. CEMENTATION OF HYDRATED-SALT SLUDGE • Assessment of the effect of a compound composition on flowability of cement-paste and mechanical strength of a solid product • Findings of the experiments: • The waste/cement ratio is the key factor that influences the flowability of the cement paste and mechanical strength of obtained compound • If waste/cementratiodecreased, the cement-paste flowability drops considerably and the mechanical strength increases. • When the waste/cement ratio was ~1.5 (water/cement ratio equals 1.1), the mechanical strength does not reach required standardized even within a year. With smaller values of waste/cement ratio (water/cement ratio), the samples develop necessary strength, but very slowly • Reduction of the iron hydroxide content in a cement compound, other conditions being equal, results in increase of the cement-paste flowability, but is of little influence on mechanical strength of a compound • Decrease of the water/cement ratio to 0.5 results in notable increase of strength, but in this case the cement paste practically loses flowability. 18

19. CEMENTATION OF HYDRATED-SALT SLUDGE • Assessment of the effect of sludge age on cement compound quality • Sludge composition: Fe(OH)3 – 30 g/l, Na2SO4 – 30g/l, NaNO3 – 240 g/l • Waste/cement ratio – 0.67, water/cement ratio – 0.5, • Loading capacity of cement compound – 19 wt %.

20. CEMENTATION OF HYDRATED-SALT SLUDGE • Continuation • Assessment of the effect of sludge age on quality of a cement compound • Findings of the experiments: • With increasing age of the hydrated-salt sludge, the cement-paste flowability drops, and the mechanical strength variation does not show a clearly defined tendency. Furthermore, in all cases the mechanical strength is much higher than the standardized required value. • During preparation of a cement compound, the false setting effect was observed. On further mixing, this effect disappears. The false-setting start time varies depending on composition of solution, its age and the mixing conditions.

21. CEMENTATION OF FILTER MATERIAL PULPS • Filter material pulps contents: • spent ion-exchange resins (IER) • spent filter perlite (FP) • manganese dioxide sludge. • IER is the mixture of cation and anion exchange resins in the ratio of 1:1 by weight

22. CEMENTATION OF FILTER MATERIAL PULPS Assessment of loading capacity of cement compounds 22

23. CEMENTATION OF FILTER MATERIAL PULPS Assessment of optimal loading capacity of cement compounds Continuation • Findings of the experiments: • During cementation of filter-material pulps (water/cement ratio – 0.9), the loading capacity of a cement compound should not exceed 10 wt % of the solid pulp components to prevent significant reduction of mechanical strength of cement compounds. • With smaller cement-compound loading capacity and water/cement ratio, the samples are developingthe strength that exceeds the required standardized value even within a month.

24. CEMENTATION OF MIXTURE OF HYDRATED-SALT SLUDGE AND FILTER-MATERIALPULPS • Assessment of the effect of the superplasticizer and the method of its introduction on cement-paste flowability • Sample composition: • Fe(OH)3-15 g/l • Na2SO4-19 g/l • NaNO3-18.5 g/l • IER -66 g/l • FP - 36 g/l • Pulp/cement ratio - 1.0 • Loading capacity - 7 wt %

25. CEMENTATION OF MIXTURE OF HYDRATED-SALT SLUDGE AND FILTER-MATERIALPULPS Continuation Assessment of the effect of the superplasticizer and the method of its introduction on cement-paste flowability Findings of the experiments: Presence of the plasticizer in the pulp and the plasticizer-introduction method have no significant effect on flowability. 25

26. CEMENTATION OF MIXTURE OF HYDRATED-SALT SLUDGE AND FILTER-MATERIALPULPS • Assessment of the effect of pulp age and pH on cement-paste flowability and cement-compound strength • Pulp composition: • Fe(OH)3-28.6 g/l • Na2SO4- 24.2 g/l • NaNO3 - 24.6 g/l • IER - 66 g/l • FP - 36.3 g/l • Pulp/cement ratio - 0.85 (equivalent of the water/cement ratio of 0.72)

27. CEMENTATION OF MIXTURE OF HYDRATED-SALT SLUDGE AND FILTER-MATERIALPULPS Continuation Assessment of the effect of pulp age and рН on cement-paste flowability and cement-compound strength 27

28. CEMENTATION OF MIXTURE OF HYDRATED-SALT SLUDGE AND FILTER-MATERIALPULPS Continuation Assessment of the effect of pulp age and рН on cement-paste flowability and cement-compound strength • Findings of the experiments: • The pulps with рН =7: • the mechanical strength does not practically depend on the pulp age when cementing. • the flowability of the cement paste with the pulp aged 10 and less days is somewhat less than that of the cemented pulps aged 21 and 31 days. • With high alkalinity of the pulp (рН =12), increased time of its holding up to one month prior to cementation does not lead to a noticeable change in the cement-paste flowability and the mechanical strength of the cement compound.

29. CEMENTATION OF MIXTURE OF HYDRATED-SALT SLUDGE AND FILTER-MATERIALPULPS • Assessment of the effect of the binder type on characteristics of cement compounds • Pulp composition: • Fe(OH)3-20 g/l • Na2SO4 -20 g/l • NaNO3-260 g/l • IER - 66 g/l • FP - 36 g/l

30. CEMENTATION OF MIXTURE OF HYDRATED-SALT SLUDGE AND FILTER-MATERIALPULPS Continuation Assessment of the effect of the binder type on characteristics of cement compounds Findings of the experiments: Using both Portland cement and Slag Portland cement as a matrix, flowability and mechanical strength of cement compoundsmeet the requirements 30

31. CEMENTATION OF MIXTURE OF HYDRATED-SALT SLUDGE AND FILTER-MATERIALPULPS Frost Resistance and Water Resistance of Cement Compounds with ILW of PA Mayak

32. CEMENTATION OF MIXTURE OF HYDRATED-SALT SLUDGE AND FILTER-MATERIALPULPS Continuation Frost resistance and water resistance of cement compounds with ILW of PA Mayak • Findings of the experiments • The all solidified samples have the required frost resistance and water resistance • The investigations on the frost resistance and water resistance of the cemented ILW of PA Mayak showed that the ability of the samples to withstand multiple freezing/thawing cycles was sharply dropped if the test samples failed to reach not less than 75 % of the final strength value • Therefore, testing of the samples with 28 days holding (as provided for by the National Standard), often leads to negative findings (important for methodology of cement compound testing)

33. CEMENTATION OF TRITIUM-CONTAINING LRW Amount of Tritium Transferred to Contact Water from Cement Compounds with Waterproof Coat within One Day

34. CEMENTATION OF TRITIUM-CONTAINING LRW Continuation Amount of Tritium Transferred to Contact Water from Cement Compounds with Waterproof Coat within One Day • Findings of the experiments: • Within the first days of the contact, as revealed by all the experiments, the tritium leaching rate was equal to 1×10-4 g/cm2 day. In three days the tritium losses are reducing • The degree of tritium retention in the magnesia-compound-based samples is somewhat less than that when using SPC and PC 34

35. CONCLUSION AND RECOMMENDATIONS: • A set of the experimental data has been obtained on characterization of the process of cementation of liquid ILW resulting from the reprocessing of PA Mayak’s SNF (hydrated-salt sludge, filter-material pulps and their mixtures0. Using the simulated LRW, it has been shown that the quality of the produced cement compound meets the national standard requirements if the Portland cement and Slug Portland cement are used as the matrix materials. • Next steps in period 2009-2010 to be taken: using the pilot facility, the technologicalprocess conditions will be developed and tested for a commercial cementation facility to provide the large-scale production of cement compounds with required quality and flowability to ensure uniform filling of storage facility compartments

36. Thank You for Your Attention Leonid Sukhanov Deputy director of SNF and RW Management Centre A.A.Bochvar Research Institute of Inorganic Materials 123060, Russia, Moscow, P.O. Box-369, Rogov Street, 5a Fax: 007-499-730-6427, E-mail: lpsoukh@bochvar.ru