Development of Technology of Sodium Hydroxide Processing into Geocement Stone
Development of Experimental-Industrial Technology of Radioactive Waste Processing into Geocement Stone and Equipment for its Realization
Tech Area / Field
- FIR-DEC/Decommissioning/Fission Reactors
8 Project completed
Senior Project Manager
Urezchenko V M
Nuclear Technology Safety Center, Kazakstan, Almaty
- KATEP-AE, Kazakstan, Almaty\nNational Nuclear Center of the Republic of Kazakstan, Kazakstan, Kurchatov\nMAEC-Kazatomprom, Kazakstan, Aktau\nNational Nuclear Center of the Republic of Kazakstan / Institute of Atomic Energy (2), Kazakstan, Kurchatov\nNational Nuclear Center of the Republic of Kazakstan / Institute of Nuclear Physics, Kazakstan, Almaty
- RWE NUKEM limited, UK, Dors, Winfrith Newburgh\nArgonne National Laboratory (ANL) / West, USA, ID, Idaho Falls
Project summaryBackground for Project.
Kazakhstan has one nuclear power reactor in Aktau that is now under decommissioning. The Soviet-designed BN-350 is a sodium-cooled, fast-breeder reactor that began operating in 1972. It was a key source of electricity and heat for Aktau, a city on the banks of the Caspian Sea in sparsely populated western Kazakhstan. The reactor also bred high purity weapons grade plutonium in its blanket whose elements were subsequently stored in the plant’s spent fuel pool. The disposition of these spent fuel elements is the subject of a separate bi-lateral project between the U.S. and Kazakhstan.
The intention was formally announced on April 22, 1999, to shutdown the reactor and take those actions necessary to place the plant in safe storage (‘SAFESTOR’) for 50 years, at which time final decontamination and decommissioning (D&D) will be performed. U.S. collaboration in planning and conducting the shutdown was requested since we do not have the indigenous resources to do the work. The point of this request is that we (Kazakhstan) need financial assistance and input from others who have experience with decommissioning sodium cooled fast reactors. Consequently, international collaborative efforts are required with other nations to successfully complete the decommissioning activities to place the plant in SAFESTOR and keep the existing resources at the plant productively employed. The experience the BN-350 operating staff will gain in the decommissioning of the plant will provide an experience base from which we can build our own nuclear safety infrastructure in conducting decommissioning activities safely and effectively and also provide an experienced staff to do this work else where in the international marketplace. The market over the next 100 years for nuclear decommissioning activities is expected to be very large.
The U.S. announced its intention to support Kazakhstan in the technical scope of actually conducting the shutdown work primarily focused on those tasks necessary to irreversibly shutdown the reactor – namely sodium draining and processing (fuel offloading is being taken care of by another U.S. sponsored project). This intention has been formalized in a bi-lateral agreement between the U.S. and Kazakhstan signed in December 1999.
The joint Kazakhstan and American program on BN-350 decommissioning involves the wide range of tasks. In particular it’s related to the sodium processing (reactor plant coolant) and disposal of fission products. Taking into consideration the particularity of physical and chemical properties of coolant the processing consists of number main phases:
1. Sodium removal from the reactor.
2. Sodium cleaning, i. e. removal of the most active radioisotopes of fission products, especially cesium-137.
3. Storage of sodium fission products during 50 and more years.
4. Ensuring control of plant conditions.
The most difficult and hazardous process is the sodium processing in a chemically passive substance, which can be stored during a long period of time in assigned places.
The technology of processing of spent liquid metal coolant in a concentrated alkaline solution, suggested and approved on an industrial scale at ANL (USA) will be applied at the BN-350 reactor. This product is not suitable for the long safe storage because of its high chemical activity in combination with the radioactivity.
It is suggested to supplement the technology of ANL with further concentrated alkaline solution processing into geocement stone. This is a perspective technology which generates the final product suitable for safe radioactive waste isolation from biosphere for a long period of time – not less than 400-500 years. Geocement is an alkaline hydraulic and binding substance forming stones while hydration hardening of mixture, including the alkaline solution, blast slags and clayey component.
With it all fixing of cesium and sodium radionuclide is the result of their inclusion into a structure of alkaline silica-alumina compounds, resulting in geocement stone. These new formations are notable for their long life and stability to natural aggressive environment.
The Kazakhstan Nuclear Technology Safety Center is in a unique position to facilitate implementation of the project by other involved Kazakhstan agencies. The NTSC was expressly set up on Kazakhstan to be a center for nuclear expertise. It is also ideally set up to be a coordinating agency within Kazakhstan for all the activities in this proposal.
Technical Objectives for Project.
The technical objective of this work is experimental checking of the technological possibility to process sodium hydroxide into geocement stone using raw materials available in Kazakhstan. At that characterization of available raw materials, their physical-mechanical behavior and chemical composition, elaboration of the optimal mixture of components, regimes and requirements to the equipment and also certification of the final product will be performed. The experimental equipment will be developed, manufactured and assembled; the whole technological cycle will be worked through up to obtaining of certified final product acceptable for disposal.
Management Objectives for Project.
Personnel from many Kazakhstan agencies will conduct the joint work in collaboration with the U.S. and other international experts. These agencies include the Mangyshlak Atomic Energy Complex (MAEC) including personnel from the BN-350 reactor, the Kazakhstan Company ‘KATEP-AE’, the Kazakhstan National Nuclear Center (NNC), the Institute of Atomic Energy NNC, the Institute of Nuclear Physics NNC, and the Kazakhstan Nuclear Technology Safety Center (KNTSC). The Kazakhstan Nuclear Technology Safety Center, in addition, will provide contract administration internal to Kazakhstan. In this capacity the KNTSC will manage the contractual interface with the other Kazakhstan participating agencies accomplishing the work, including coordinating agreements on scopes of work, administrative review of deliverables provided by the other Kazakhstan agencies, and payment or providing required materials to other participating agencies. The KNTSC will also provide travel expenses and arrange for administrative and meeting expenses to support the project.
Technical Strategy for the Project.
The strategy for development of technologies includes several tasks. Namely, these tasks are:
Tasks 1 - Data gathering and investigation of existing and developing technologies.
Data gathering and investigation of existing and developing technologies and equipment from other similar programs. This would include the work being done on waste form development for the SuperPhoenix sodium hydroxide as well as the work being performed in Japan and elsewhere. Formal meetings may be required in order to obtain the most useful information for implementation into the waste form development in Kazakhstan. An option study would be performed based on the data gathered, specifying the direction for the investigation.
Task 2 – Characterization of the final product initial components.
The characterization of the raw materials available in Kazakhstan. The work includes gathering of initial data on available materials, taking of components’ samples, physical-mechanical behavior and chemical composition investigation, experimental assessment of the technology application, selection of components based on results obtained.
Task 3 – Development of Program of experimental investigations and laboratory elaboration.
The Program will be developed after obtaining information on technologies existing around the world and data on existing in Kazakhstan prospective materials. The development of this Program will allow to choose the most important investigations and technological developments implementation of which will lead to expecting results.
Task 4 – Experimental investigations and elaboration of technology of transfer of radioactive waste into geocement stone.
Experimental investigation of sodium hydroxide concentration and mixture receipts on physical-mechanical behavior of geocement stone are included in this task. The influence of sodium hydroxide concentration derivable by ANL-W technology is investigated both analytically and experimentally. The results of this work directly influence the final product form produced by sodium processing facility. The samples of the final product may be subjected to irradiation and then physical-mechanical behavior including leachability testing. Collaboration with Kazakhstan university professors in the areas of inorganic chemistry and silicate systems will be conducted. A report will be generated documenting the results of these investigations and specifying the selection of the sodium hydroxide concentration and other process parameters.
Cementing technology elaboration. The work includes the optimization of the technology regimes and elaboration of requirements to technological equipment for full-scale technology realization. The report will include the conditions, process, materials, and equipment necessary for the full scale cementation system. Included will be a study of the options for final waste form size, shape, and container.
Task 5 – Final product certification.
Final product certification. The work includes determination of physical-mechanical behaviour of the product to confirm that it meets necessary requirements to geocement stone. Certified methods, devices and equipment will be used. Samples will be submitted to a certified, independent laboratory for confirmation of waste form performance. The laboratory will prepare a report confirming the waste form meets the certification standards as defined in regulatory documents for burial of radioactive waste in Kazakhstan.
Task 6 – Development of Technical Task for design of Experimental-Industrial Equipment to process radioactive waste into geocement stone.
A Technical Task will be developed determined what has to be designed, for what goals, and determined functional requirements for systems and product.
Task 7 – Experimental-Industrial Equipment design elaboration to process radioactive waste into geocement stone.
Model simulation equipment design development for processing of radioactive waste into geocement stone. The full set of design documents for siting, construction, and utility requirements for putting the equipment into operation will be elaborated, including an Environmental Impact Assessment, Quality Assurance Plan, and Safety Analysis Report. The project will be coordinated with necessary regulatory bodies. This task combines preliminary, technical, and working designs.
Task 8 – Manufacturing and assembling of the Model Simulation Equipment.
The manufacturing and assembling of the model simulation equipment. Full scale model simulation equipment will be procured, fabricated, and installed in a building to be provided by Kazakhstan at the BN-350 site.
Task 9 - Start-up testing and experimental operation of the model simulation equipment.
Start-up testing and experimental operation of the equipment. The equipment and process will be tested and verified to perform according to the design and waste form specifications. The testing will be performed with radiologically uncontaminated material to avoid contamination of the equipment prior to certification of the equipment and process.
Task 10 - Final report.
Final report. A final report summarizing the results of Tasks 1 through 9 will be prepared and submitted to ISTC.
Task 11 – Project management.
This task involves work by the Kazakhstan Nuclear Technology Safety Center to manage the designated work with the other agencies within Kazakhstan in support of this contract. KNTSC responsibilities include administrative review of deliverables (to assure completeness), translation of the deliverables as necessary, arrangement for and implementation of payment and material procurements/transfers to appropriate personnel at the other agencies, confirmation of payment/material receipt, and maintenance of financial records, wages paid, and other payment documentation.
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