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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...

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Highly pure nitrogen is used in the high-pressure gas (HPG) system to maintain within certain limits the chemical parameters of the coolant in the first loop of a nuclear power plant. The most important parameter of the nitrogen quality is the oxygen content. According to the standards [1], it should not exceed 0.1% by volume. Since monitoring instruments are not available, it was decided that an apparatus for obtaining nitrogen samples and for performing laboratory measurements of oxygen in it should be developed.The apparatus and instruments must meet the following requirements: possibility of obtaining samples before and after nitrogen is fed into the HPG system; nitrogen samples should be obtainable from the base nitrogen pipeline near the deck insert; samples should be obtained with the air oxygen admixture in the nitrogen sample not exceeding 0.02% by volume; the radiation environment near the base pipeline should be safe during emission of radioactive gas into the atmosphere; and, the oxygen content in the nitrogen samples must be measured reliably in the concentration range from 0.5 vol. % in the presence of up to 2 vol. % hydrogen.The variant shown in Fig. 1 of the sampling apparatus was chosen after the construction was worked out. Principle of Operation of the Apparatus. After the valves are opened, nitrogen under a pressure of 13 MPa flows into the pressure equalizer 2 (the manometers 3 monitor the pressure) and then into the working tank 4 with the pressure raised up to 1 MPa (the manometer 5 monitors the pressure). The sample is redirected into the chamber of the radiometer RV-4 or KRK-1 in order to measure the volume radioactivity. The tanks in the working group of the HPG system are connected with the volume equalizer in the first loop of the nuclear power plant, and some of the radioactive gas, consisting of krypton and xenon, flows into the tanks of the HPG system. The hydrogen formed during radiolysis of the water in the core also enters the nitrogen in the tanks of the HPG system.At radioactivity levels less than 3.7.104 Bq/liter it is permitted to release hydrogen into the atmosphere. The nitrogen samples were obtained no sooner than five days after the reactor was stopped, at which time the main radioactive impurities will be 85Kr and t33Xe, whose maximum admissible concentration at an open category-A location is equal to (3.7-7.4). 103 Bq/liter [2,3]. At higher levels of radioactivity the nitrogen is passed through an activated-charcoal filter which catches the krypton and xenon. After the working chamber is filled and emptied three times, the fourth portion of nitrogen flows into the laboratory for analysis. The apparatus was fabricated in the form of three portable units, two of which consist of stainless steel containers and the third consists of a carbon filter in the form of two serially connected cylinders. The container in the first unit contains a sampler, tubes connected to the base pipeline 1 and the exhaust pipe 6. The container in the second unit consists of two reserve working ...