The Article contains the results of the study performed for the samples made from alloys PT-7М, 42ХНМ, Inconel 690, Incoloy 800 for resistance against hot salt corrosion in the mixture of crystallized NaCl and KBr salts, in ratio 300:1 by weight, and in the temperature range from 150 °С to 300 °С, both in contact with the air and in a leak-tight autoclave in the atmosphere of saturated water steam. Regularities of hot salt corrosion behavior in the alloys under the study were detected under testing conditions. The atmosphere of saturated water steam inhibits development of halt salt corrosion of alloy ПТ-7М in the entire temperature range of the testing.
The structural features and operating experience of reactors in Russian atomic ships and icebreakers have been described in many articles and monographs, and particularly in [1][2][3][4]. However, certain aspects of the design and operation are known only to specialists directly involved with them. The present authors have been guided by the desire partially to remedy this omission and also to base approaches to the water chemistry of reactors on projected floating power units and low-power nuclear power stations.The material used in the present article is mainly contained in technical scientific reports and operating documentation. A large volume of information accumulated in laboratory research on water-chemical processes, bench tests and (chiefly) in the course of prolonged operation make it possible to propose a generalized approach to the water chemistry of shipborne reactors.Operation over many years has shown the ammonia-water-chemical regime with gas (nitrogen) pressure compensation, used in the first loop of atomic ice breakers and recommended for projected floating power units and low-power nuclear power stations, to be quite simple and reliable.By utilizing nitrogen in the pressure compensation system, replenishing the first loop with ammonia solution, and using KU-2-8Chs strongly acidic cationite in ammonium form and strongly alkaline AV-17-8Chs anionite in hydroxyl form as the filler of the ion-exchange filter, a high pH value (9-10.5) is sustained with an excess hydrogen concentration. The radiolysis of water is then completely suppressed, there is no oxygen or other oxidizing components, and there is a reduction in the rate of corrosion of the structural materials of the loop, sludging, and sludge separation [5]. The regime is characterized by stability and the ability to self-regulate.The water quality norms given in Table 1 were chosen and refined from the results of investigations of the water-chemical regime obtained from special test benches and operating experience. The work was performed with the aim of increasing the stability of the regime and simplifying the technological methods for organizing it. By increasing the stability of the regime it was possible to reduce the number of water-chemical monitoring indices and to establish the minimum number of necessary requirements for monitoring and sustaining them.An analysis of the factors influencing the water-chemical indices provides evidence that the state of the medium and the stability of the regime during normal operation depend, as a rule, on the water quality of the initial filling and replenishment, the processes determining transport in the high-pressure gas system and the quality of the working gas, and the way in which the corrosion processes occur on the internal surfaces of the loop during operation.Among the factors influencing the quality of the medium we omit from consideration events related to irregular situations, including accident s~tuations. From operational experience these include salination from the second loop, error...
The storage and disposal of decommissioned atomic submarines is an important problem today. Large numbers of atomic submarines have been removed from service by international arms-limitation treaties and also simply because they are old and out of date, but no strategy for their disposal exists. At the same time, the high cost of effective disposal entails a stepby-step approach. In the present work, on the basis of an analysis of the problem, we identify areas that call for high-priority investigation in order to ensure radiational and nuclear safety of decommissioned submarines.Disposal of submarines involves the following sequence of steps: removal from operation and preparation for long-term storage; storage with the active zone; removal of the active zone; treatment of the reactor unit and the associated equipment so as to permit long-term storage after removal of the active zone; storage and transportation of the spent nuclear fuel; dismantling of the reactor unit and transportation to the storage site; and storage and burial of the radioactive waste.In numerous papers on this topic, in presentations at conferences and symposia, and in research and development work conducted by various organizations, strategic issues of dismantling the submarines and storage of the wastes after dismantling -i.e., the fina! stages of this sequence -have mainly been considered. These stages are not critical in terms of nuclear and radiation safety, and moreover, in view of the economic situation, are impracticable at this point.To determine the problems critical to nuclear and radiation safety, we must analyze the situation at each step in the sequence.Removing the submarine from service and switching the reactor to long-term storage mode prior to unloading depends on the state of the particular submarine and prevailing technological conditions. This step calls for the following basic operations:oconversion to a state meeting nuclear and radiation safety requirements with a minimum of technical work on the reactor and the system as a whole; ointroduction of specially developed aqueous-chemical conditions with minimum release of radionuclides into the primary loop; oadoption of engineering and organizational measures eliminating unsanctioned access to the reactor; omaintenance of a temperature no lower than 5~ in the buildings. The current lack of financing, along with the available transport systems and systems for unloading, transporting, and storing the nuclear fuel, is hindering the rate at which active zones are unloaded from decommissioned submarines. Submarines from which the spent nuclear fuel has not been unloaded are accumulating.According to data presented at a conference in Severodvinsk in March 1995, around 120 submarines have currently been withdrawn from service in the North Atlantic and Pacific Fleets and are berthed in various bays of the Kol'sk peninsula, Primor'ye, and Kamchatka. The fuel has still to be unloaded from more than 60% of these. By 2000, the number of submarines awaiting disposal may reach 160-1...
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