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This paper presents the evaluation of the degree of pollution of wastewater from oil mills and margarine in Romania. Preliminary experimental researches were conducted on polymer flocculent material obtained by irradiation with accelerated electrons , type PA ( AMD -AA -40 ) , copolymers of acrylamide and acrylic acid , used alone or in combination with classical electrolytes in difficult waters , in relation to the effectiveness of the treatment of classical chemical agents , such as ferrous sulphate , aluminum and lime. [ABSTRACT FROM AUTHOR]

The aim of this study is to identify the fuel channel components and the reference plans based on which is made the installation into calandria of CANDU 6 nuclear reactor. The CANDU 6 is a 740 MW pressure tube reactor designed by Atomic Energy of Canada Limited (AECL) to provide safe and reliable nuclear power. It is an evolution of the previous CANDU reactor, and it is designed to be licensable internationally by ensuring its compliance with the latest Canadian nuclear regulations and the fundamental safety principles of the International Atomic Energy Agency (IAEA) Safety Standards. The CANDU reactor design is based on the experience derived from preceding CANDU reactors and virtually every design feature of the latest CANDU reactor is identical to, or it is an evolutionary improvement of, an earlier proven design. The design of the CANDU fuel channel is accordingly the result of continuing intensive engineering development of its major components. The reactor assembly of the CANDU 6 nuclear reactor consists of the horizontal, cylindrical, low-pressure calandria and the endshield assembly. This enclosed assembly contains the heavy water moderator, the 380 fuel channels assemblies and the reactivity mechanisms. The fuel channels are one of the major distinguishing features of a CANDU reactor and their reliability is crucial to the performance of the reactor. Each fuel channel consists of four major components: the pressure tube, the calandria tube, the annulus spacers and the end fittings. Fuel bundles are enclosed in the fuel channels that pass through the calandria and the end-shield assembly. The fuel channel is designed to ensure a radiation exposure protection of workers and public, during the reactor operation. The fuel channels are assembled and installed into the calandria vessel at the reactor site following installation of the calandria. The fuel channel assembly is made according with the specific requirements of reference planes definition, reference planes measurements, tools and equipments, installation procedures and the quality assurance program. Defining reference plans, measurements reported to reference plans and installation procedures to a new fuel channel in the calandria CANDU nuclear reactor comply the requirements described in the AECL (Atomic Energy of Canada Limited) specified documents. [ABSTRACT FROM AUTHOR]

Based on the knowledge referring to assembly the fuel channel into calandria of CANDU 6 nuclear reactor, the purpose of this study is to achieve possible method for decommissioning of the horizontal fuel channels of calandria vessel. As long as nuclear power plants are reaching their end of lifecycle, the decommissioning of these installations has become one of the 21st century's great challenges. Every project may be managed differently, depending on the country, development policies, financial considerations, and the availability of qualified engineers or specialized companies to handle such projects. The main objective of decommissioning is to place a facility into such a condition that there is no unacceptable risk from the decommissioned facility to public health and safety of the environment. The overall decommissioning strategy is to deliver a timely, cost-effective program while maintaining high standards of safety, security and environmental radiation protection. If facilities are not decommissioned, they could degrade and potentially present an environmental radiological hazard in the future. Simply abandoning or leaving a facility after ceasing operations is not considered to be an acceptable alternative to decommissioning. The decommissioning activities performed are administrative and technical, and include the preparation, endorsement and approval of documents, obtaining permits and authorizations, providing financial resources, decontamination, dismantling, demolition, controlled removal of equipments, components, conventional or hazardous waste demonstrating the fulfillment of the radiological conditional or unconditional release of the facility and the ground included in the decommissioning project. Nuclear decommissioning consists in a planning phase and the implementation of all procedures and operations. The decommissioning of fuel channels represents one of the last operation which is performed in the nuclear power decommissioning and it is the most important operation in the nuclear reactor dismantling. The radiological safety analyses should be made by certified experts for protection assessment to radiation exposure of workers in time of fuel channel dismantling. The dismantling of fuel channels represents the final phase of nuclear facility decommissioning and refers to the technical operations taken to extract the components from inside of the nuclear reactor channel. It is a complex process and requires activities such as disassembly decommissioning device, locking/unlocking the channel closure and the shield plug, pressure tube cutting, extracting of each component from the channel, as well as radioactive waste management. The dismantling operation stages of the fuel channel components should be repeated for each of all 380 channels of the reactor, starting from the front of calandria side and continuing with the rear side. The final aim of decommissioning is to recover the geographic site to its original condition. [ABSTRACT FROM AUTHOR]

This paper present a constructive solution proposed by the authors in order to achieve of a cutting and extracting device for the decommissioning of the horizontal fuel channels in the CANDU 6 nuclear reactor. One of the most important part of the decommissioning device is the Cutting and Extraction Device (CED) which perform the dismantling, cutting and extraction of the fuel channel components. This flexible and modular device is designed to work inside the fuel channel. The main operations performed by the Cutting and Extraction Device (CED) are dismantling and extraction of the channel closure plug and shield plug, cutting and extraction of the pressure tube. The Cutting and Extraction Device (CED) consists of following modules: guiding-fixing module, traction modules, cutting module, guiding-extracting module and articulated elements for modules connecting. The guiding-fixing module is equipped with elastic guiding rollers and fixing claws in working position, the traction modules are provided with variable pitch rollers for allowing travel speed change through the fuel channel. The cutting module is positioned in the middle of the device and it is equipped with three roll knives for pressure tube cutting, having a system for cutting place video surveillance and pyrometers for cutting place monitoring temperature. The operations performed by the Cutting and Extraction Device (CED) of fuel channel are as follows: unblock and extract the channel closure plug, unblock and extract the channel shield plug, block and cut the middle of the pressure tube, block and cut the end of the pressure tube, block and extract the half of pressure tube. The Cutting and Extraction Device (CED) is fully automated, connected by wires to a Programmable Logic Controller (PLC) and controlled from a Human Machine Interface (HMI). The design of the Cutting and Extraction Device (CED) shall be achieved according to the particular features of the fuel channel components to be dismantled and to ensure radiation protection of workers. [ABSTRACT FROM AUTHOR]

The objective of this paper is to present a possible solution for the designing of a device for the decommissioning of the horizontal fuel channels in the CANDU 6 nuclear reactor. The decommissioning activities are dismantling, demolition, controlled removal of equipment, components, conventional or hazardous waste (radioactive, toxic) in compliance with the international basic safety standards on radiation protection. One as the most important operation in the final phase of the nuclear reactor dismantling is the decommissioning of fuel channels. For the fuel channels decommissioning should be taken into account the detailed description of the fuel channel and its components, the installation documents history, adequate radiological criteria for decommissioning guidance, safety and environmental impact assessment, including radiological and non-radiological analysis of the risks that can occur for workers, public and environment, the description of the proposed program for decommissioning the fuel channel and its components, the description of the quality assurance program and of the monitoring program, the equipments and methods used to verify the compliance with the decommissioning criteria, the planning of performing the final radiological assessment at the end of the fuel channel decommissioning. These will include also, a description of the proposed radiation protection procedures to be used during decommissioning. The dismantling of the fuel channel is performed by one device which shall provide radiation protection during the stages of decommissioning, ensuring radiation protection of the workers. The device shall be designed according to the radiation protection procedures. The decommissioning device assembly of the fuel channel components is composed of the device itself and moving platform support for coupling of the selected channel to be dismantled. The fuel channel decommissioning device is an autonomous device designed for dismantling and extraction of the channel closure plug and shield plug, extraction of the end fitting, cutting and extraction of the pressure tube. The fuel channel decommissioning device consists of following major components: coupling and locking fuel channel module, assembly valve for access to the fuel channel, storage tubes assembly for extracted components, handling elements assembly, cutting and extraction device and housing device. The design of the device and platform support is achieved according to the particular features of the fuel channel components to be dismantled in the program of nuclear reactor decommissioning according to all the safety aspects and environmental protection during the activities, resulting from the decommissioning plan developed. [ABSTRACT FROM AUTHOR]

The scope of this paper is to obtain the needed information on main steps necessary to assembly the fuel channel into calandria of CANDU 6 nuclear reactor. The CANDU fuel channel is essentially the same in all CANDU reactors and it is considered a fundamental building block in the CANDU system and their reliability is crucial to the reactor performance. The fuel channels have a high importance for the operation of CANDU nuclear reactors because they allow new refueling while operating at full capacity. The reactor assembly consists of a hollow cylindrical structure called the calandria assembly, fuel channels and control mechanisms of reactivity. The 380 fuel channels are composed of pressure tubes, made of zirconium-niobium alloy, located inside the calandria tubes, with two end fittings mounted, that are connected by the pipes network of the cooling supply feeders. Each CANDU fuel channel consists of four major components: the pressure tube, the calandria tube, the annulus spacers and the end fittings. The install operations to a new fuel channel must comply with the described requirements from the specified documents by AECL. The main installation operations are the roll expansion of the pressure tube ends into the two end fittings, the welding of the end fittings to the bellows and the installation of the positioning assemblies. Following installation and inspection of all 380 channels, the feeder pipes of the cooling system are connected to the end fittings. After each operation, the resulting information must be recorded in the specific registration and verification documents of each component and each operation. The registration documents, the check documents and the related reports of the fuel channel installation are part of the processes records of the assembly history of the nuclear reactor. All these documents and reports will be archived in order to take anytime a sequential picture of each fuel channel. The radiological safety analyses are made by certified experts for assessment of radiation exposure of workers and public. [ABSTRACT FROM AUTHOR]

The aim of this study is to identify the fuel channel components and the reference plans based on which is made the installation into calandria of CANDU 6 nuclear reactor. The CANDU 6 is a 740 MW pressure tube reactor designed by Atomic Energy of Canada Limited (AECL) to provide safe and reliable nuclear power. It is an evolution of the previous CANDU reactor, and it is designed to be licensable internationally by ensuring its compliance with the latest Canadian nuclear regulations and the fundamental safety principles of the International Atomic Energy Agency (IAEA) Safety Standards. The CANDU reactor design is based on the experience derived from preceding CANDU reactors and virtually every design feature of the latest CANDU reactor is identical to, or it is an evolutionary improvement of, an earlier proven design. The design of the CANDU fuel channel is accordingly the result of continuing intensive engineering development of its major components. The reactor assembly of the CANDU 6 nuclear reactor consists of the horizontal, cylindrical, low-pressure calandria and the end-shield assembly. This enclosed assembly contains the heavy water moderator, the 380 fuel channels assemblies and the reactivity mechanisms. The fuel channels are one of the major distinguishing features of a CANDU reactor and their reliability is crucial to the performance of the reactor. Each fuel channel consists of four major components: the pressure tube, the calandria tube, the annulus spacers and the end fittings. Fuel bundles are enclosed in the fuel channels that pass through the calandria and the end-shield assembly. The fuel channel is designed to ensure a radiation exposure protection of workers and public, during the reactor operation. The fuel channels are assembled and installed into the calandria vessel at the reactor site following installation of the calandria. [ABSTRACT FROM AUTHOR]