Cleanup of High Level Waste Tanks
Cleanup of High Level Waste Tanks. Technology Development
Tech Area / Field
- ENV-RWT/Radioactive Waste Treatment/Environment
3 Approved without Funding
VNIITF, Russia, Chelyabinsk reg., Snezhinsk
- University of Missouri-Rolla / Rock Mechanics and Explosives Center / High Pressure Water Jet Laboratory, USA, MO, Rolla\nANT AG, Germany, Lübeck\nToyo Consultant Corporation, Japan, Tokyo\nHammelmann Maschinenfabrik GmbH, Germany, Oelde
Project summaryOne of the main environmental activities in the nuclear power industry is storage and reprocessing nuclear wastes, which are the major source of radionuclides migration into environment at nuclear facilities. Significant amounts of liquid and solid radioactive wastes have been accumulated at nuclear facilities of Russia during the five last years. These wastes are the source of potential severe hazard for population and adjacent territories. High-level LRW, stored in special underground tanks are the most severe hazard from all wastes. Designs of these tanks were developed through many years and were improved alongside with accumulated knowledge. These tanks are carefully watched by the engineers throughout the operation term, who monitor their state, and by the scientists, who are searching the most advanced technologies for LRW storage and reprocessing to more safe state.
The tanks design undergo natural degradation in the process of long-term storage e.g. due to corrosion and the failures of cooling system may result from this degradation. Thus it is extremely important to reveal beforehand potentially hazardous sites of design and to perform repair works. This task as a rule is combined with removal of LRW and bottom sediments (refereed to as salt-cake) from the tank, its washing to the radioactivity level allowing performance of repair works by the personnel. The whole technological cycle of washing lasts at least two years. This technology is extremely costly and labor intensive. Significant amounts of secondary radioactive wastes, incurring new costs for storage and reprocessing appear in the process of washing. Human involvement is extremely undesirable factor of this technology due to the risk of exposure. The personnel has to perform extremely labor intensive operation of tank stripping, i.e. making a hole in meter and a half layer of “heavy” concrete, plugging the tank in some cases to perform monitoring and repair operations.
One of Minatom enterprises, facing the most urgent problems of search for more advanced technologies for tanks stripping and cleanup is PA Mayak, having more than fifty years long experience of LRW tanks operation. Its spent nuclear fuel reprocessing plant has vast network for storing various LRW (including several dozens of tanks). Currently the plant spends big amounts for tanks repair and bears sizable losses from repair demurrage associated with lack of advanced technologies.
Besides there are many buildings and facilities at Mayak to be decontaminated and dismantled due to decommission from weapon programs or contaminated during radiation accident 1957. One of the problems of tanks cleanup There are similar problems associated with tanks cleanup, dismantlement and decontamination at other Minatom enterprises, such as Krasnoyarsk-26 and Tomsk-7.
This problem is also urgent in other countries dealing with reprocessing of spent nuclear fuel. So in the US Oak Ridge, Hanford and Idaho Falls facilities face the same problems.
The first phase of “Tanks cleanup” project was completed within ISTC Partnership Project #1815Р with a company RedZone Robotics Inc. (USA). Results of this project include:
- Performed analysis of relevant information about current tank contents and selection of standard target tank;
- Concept of RFNC-VNIITF abrasive water-jet cutting equipment was developed, it was demonstrated that performance features of RFNC-VNIITF equipment are not sufficient and either more powerful injection cutting system or novel suspension cutting system should be developed;
- Concept for accelerated cleanup was developed;
- Procedures for further technology development in “cold” and “hot” environment using water-jet equipment of the companies WOMA, ANT, Hammelmann and of RFNC-VNIITF were proposed;
- Estimates of schedule and budget for development of technical facility for these activities were developed;
- Regulations related to wastes cleanup at PA Mayak, including wastes handling, safety requirements, health and personnel safety restrictions were studied;
- Feasibility of joint commercial activities in Russia was demonstrated.
Project participants are the specialists, earlier engaged in development and testing of nuclear weapons. They were engaged in development of mobile water-jet cutting equipment and technologies based on this equipment. The project dealing with development of accelerated technology for tanks cleanup is supported by administration of RFNC-VNIITF and PA Mayak. In 1998 it has been approved by the management of MinAtom and MinNauki (Ministry of Science of Russia) and by US DOE. Employees of Mayak PA dealing with LRW handling will participate in this project beside RFNC-VNIITF staff.
Expected Results and Their Application
This proposal refers to the category "Applied research", technology area is environmental studies, handling radioactive wastes, ISTC code is ENV-RWT
Following results are expected:
1. Delivery of abrasive water-jet injection system of Hammelmann company and of suspension system of ANT company and training of personnel. Equipment adaptation to Russian environment.
2. Development of tank model, of handling system and accessories for process studies in “cold” environment.
3. Studies of process parameters of abrasive water-jet cutting of “heavy” concrete by the systems of injection and suspension cutting. Studies of process parameters of water-jet cleaning of surfaces and sluicing of bottom sediments of the tank. Selection and optimization of process parameters.
4. Development of pilot technology and its testing in “cold” environment.
Pilot technology will be the major outcome of the project. Results of “cold” testing are to be used for development and testing of operational technology for plant conditions (“hot” environment) as well as for the estimates of process cycle of cleanup of all LRW tanks of PA Mayak.
Results of studies under the project will be used for ordering water-jet cutting equipment and remotely controlled tools instead of operations involving personnel.
Project results are also to be used for estimate of further commercial activities feasibility in the form of joint venture with RFNC-VNIITF (ca. 30 new jobs). Expected field of joint venture activity is application of remotely controlled abrasive water-jet cutting equipment in industrial process where presence of personnel is extremely complicated or hazardous.
Meeting ISTC Goals and Objectives
1. The project is aimed at resolution of environmental problems associated with LRW disposal, reduction of threat of radioactive contamination propagation and recovery of lands around nuclear facilities;
2. Scientists and engineers of RFNC-VNIITF and of PA Mayak earlier engaged in development and testing of nuclear weapons and its components will be engaged in the studies within the project;
3. These studies lay grounds for long-term activities of project participants and strengthening Russian capabilities in the field of radioactive wastes disposal;
4. The project is helpful for international community as it provides a new experience in resolution of LRW disposal problems and improvement of environmental conditions;
5. The project contributes studies transition to commercial stage by drawing-up and implementation of plans of joint with a Partner commercial activities (joint venture).
Scope of Activities
This project envisages studies including setting up and delivery of equipment by the companies Hammelmann and ANT, training of personnel, adaptation of equipment to conditions and equipment of RFNC-VNIITF, development of tank model and of handling systems, process studies and testing of pilot technology in “cold” environment, development and improvement of cutting and cleaning technology, studies of opportunities of cutting intensification in winter conditions.
Project activities are to be performed during 2.5 years (30 months). Total labor effort will be 530 man-months. Project includes 4 tasks and 18 stages.
Role of Foreign Collaborators
- Delivery of water-jet cutting equipment;
- Training of RFNC-VNIITF personnel to procedures of water-jet cutting equipment operation and maintenance;
- Consultations and information exchange in the course of the project;
- Conduct of joint workshops;
- Testing and evaluation of technology/equipment developed under the project;
- Participation in technology demonstration in RFNC-VNIITF.
Technical Approach and Methodology
Analysis of problems associated with LRW disposal indicates that new advanced and environmentally safe technologies should be developed to accelerate the pace of reprocessing of LRW stored in PA Mayak tanks and to solve the environmental issues related to decommissioning of weapon programs legacy facilities and buildings contaminated in the accidents.
Development of accelerated technology is based on application of water-jet cutting equipment of various systems in the existing processes of tanks cleanup and decommissioning of structures made of “heavy” concrete.
Keeping in mind potentially hazardous nature of PA Mayak production facilities and high responsibility for safety of nuclear facilities operation, technology development should be first performed in environment without radioactive contamination (“cold” environment) and than transferred to testing at standard tank of LRW reprocessing plant (“hot” environment).
Studies of process parameters include:
- Development of cutting and cleaning modes using model samples and full-scale fragments of “heavy” concrete and simulators of bottom sediments;
- Development of pilot technology in “cold” environment using a model of standard tank;
- Studies of opportunities of cutting intensification due to application of liquid polymers and opportunities of cutting in winter conditions;
Validation of developed technology will be performed by testing on model fragments of standard tank (“cold” testing).
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