Das Projekt "Automated measuring system for waste from dismantling of the KKN plant, to be released" wird vom Umweltbundesamt gefördert und von NIS Ingenieurgesellschaft mbH durchgeführt. Objective: an important task in the decommissioning of nuclear installations is the proof of the very low radioactivity levels, allowing for free release of the generated waste. This proof involves long measuring times on a great number of representative samples out of important masses of metal structures and concrete, and considerable radiation exposure of the measuring staff. The main objective of the present research is the development, construction and large-scale testing of a prototype for an automatic measuring system, appropriate to treat important masses of waste, with low-level activities and different nuclide compositions and shapes. It is expected to minimise human errors by automatic operation. The measuring system will be designed as a mobile unit, with a modular structure allowing for a general purpose application to lwr typical waste arising, at different decommissioning sites. The practical testing will be done a total mass of 1000 mg in the framework of the kkn decommissioning. The study will be completed by a conclusive assessment of the merits of the developed measuring system for large-scale operation. General information: b.1.conceptual studies for the definition of the requirements for a measuring system, including assessment of existing low-level activity measuring techniques, definition of the types of waste to be treated, and health physics protection considerations. B.2. Preparation of a design of the complete measuring system, including detectors, control and transport system, general purpose software for measuring data processing, followed by a call for tenders and the choice of manufactures. B.3. Preparation of a licensing dossier for experimental operation of the measuring system programme. In the framework of the decommissioning of kkn. B.4. Execution of a large-scale test programme. B.5.conclusive assessment of the appropriateness of the developed measuring system, considering technical and economic aspects. Achievements: the dismantling of nuclear facilities requires proof that the radioactivity levels of materials to be released from restricted areas remain below low limiting values. Up till now, decisive measurements have been almost impossible on parts and material with complex geometries. In order to keep measurement costs low, a device has been developed which uses a fast automatic procedure to examine large amounts of dismantled and potentially contaminating components. The device measures the gross gamma-radiation which has a higher penetrating capacity into the material than beta radiation. The measuring tunnel is 1.2 m broad and 1.2 m high. Parts to be measured can be up to 4 m long and weigh 1 tonne. Analysis of measurements has shown that the specified minimal detectable activity level of 1000 bq cobalt-60 can be achieved, even with steel shielding of 2 cm thickness.
Das Projekt "Demonstration of explosive dismantling techniques of the biological shield of the Niederaichbach nuclear power plant (KKN)" wird vom Umweltbundesamt gefördert und von Battelle-Institut e.V. durchgeführt. Objective: This project aims at demonstrating explosive dismantling techniques on the biological shield of the nuclear power plant Niederaichbach (KKN), which was operated from 1972 to 1974 and is foreseen to be completely removed. The radioactive inventory of the shield is estimated in the order of 3.7E9 Bq (0.1 Ci). The level of activation is estimated to be in the order of 10 Bq/g, and the associated dose rates in the order of 10 micro Sv/h. Within this contract, blast peeling of the activated concrete from a 30C sector of the biological shield will be performed. This technique will be applied as one of 2 main techniques (hydraulic hammer besides blast peeling) for the dismantling of the whole biological shield of KKN; for this, the licensing authorities have already given their agreement. This demonstration project will be conducted according to the guidelines of the ongoing total dismantling of KKN. In particular, the generation of specific data on costs, working hours and job doses as well as on the amount of created secondary waste is considered as an important objective of this project. This will facilitate the application of this technology and acceptance from the safety point of view in future large-scale decommissioning operations. The project is a follow-up of small-scale work on inactive samples performed jointly under contracts FI1D0011 and FI1D0012. The work programme will be implemented jointly by three main contractors: Battelle Europe e.V./Frankfurt (BE), acting as coordinator, Noell/Würzburg (Noell) and Siemens/KWU (Siemens), as well as Stangenberg, Schnellenbach and Partner (SSP) as sub-contractor. Further cooperation is foreseen with TUV Bayern for the assessment of air filter systems. General Information: WORK PROGRAMME: 1. Preparatory planning and design work for on-site equipment and regulatory requirements (BE, Noell); 1.1. Layout of blasting patterns and of bore holes charging, according to the area of application (BE); 1.2. Design of blasting schemes according to the area of application (BE); 1.3. Definition of blasting area sub containments for the retention of dust, including associated filter systems (Noell, BE); 2. Demonstration blasting on the KKN shield by manual handling (BE, Noell); 2.1. Site preparation for the installation of tools and measuring devices (BE, Noell); 2.2. Assessment and implementation of auxiliary techniques such as bore hole drilling, cutting of the reinforcement by hydraulic shears, use of a hydraulic ram (Noell); 2.3. Main operation and concrete removal, consisting of a sequence of about 10 individual blasts, including pre- and post-blast working (BE, Noell); 2.4. Assessment of blasting performance, with respect to predetermined criteria such as concrete removal rate, safety aspects, integrated doses and generation of secondary waste (BE, Noell); 3. Assessment of dust retention by industrial filter systems with respect to efficiency and safety of handling (Noell, BE); 4. Assessment of ...
Das Projekt "Effectiveness and long-term behaviour of cleanable high efficiency aerosol filters" wird vom Umweltbundesamt gefördert und von Technischer Überwachungsverein Bayern Sachsen durchgeführt. Objective: Because of the high quantity of dust generated by various cutting/dismantling processes, frequent replacement of high-efficiency sub-micron particulate air filters is necessary. If such filters could be cleaned during service, costs for the replacement of the filters, radiation exposures and the amount of secondary waste could be reduced. The effectiveness in long-term operation (approx. one year) of high-efficiency sub micron particle air filters will be investigated in the framework of the dismantling of the Niederaichbach nuclear power station (KKN) in Germany. A high-efficiency sub micron particle air filter system will be exposed to heavy dust generation during the remote-controlled dismantling of KKN primary circuit pressure tubes, and therefore must be dedusted periodically. The dust is radioactively charged (essentially cobalt-60 and iron-55). The radioactivity could amount to approximately 1E5 Bq/g (pressure tubes and moderator tank) and the dose rate to 0.1 Sv/h. There is at present no experience on the effectiveness and the long-term behaviour of high-efficiency sub micron particle air filters that are dedustable during operation. General Information: WORK PROGRAMME: 1. Installation of the filters; 2. Determination of the main parameters of the clean filter station; 3. Continuous measurements (pressure pickups, air humidity and temperatures) during cutting of KKN primary cooling circuit (activated cooling channel tubes inside the reactor vessel); 4. Final evaluation including radiation exposure of workers, secondary waste arisings, specific costs, effectiveness and long-term behaviour of the filter system. Achievements: Because of the high quantity of dust generated by various cutting/dismantling processes, frequent replacement of high efficiency sub micron particulate air filters is necessary. If such filters could be cleaned during service, costs for the replacement of the filters, radiation exposures and the amount of secondary waste could be reduced. The effectiveness in long term operation of high efficiency sub micron particle air filters is investigated in the framework of the dismantling of the Niederaichbach nuclear power station (KKN) in Germany. ...