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PNC TJ9381 94-001, 84 Pages, 1994/02
The study in last year examined the realization of 1000MWt natural circulation ATR. In this study. The sensitivity analysis is did making for the design. The results are as below. (1)The influence of riser pipe diameter. The natural circulation on riser pipe 3B is analyzed. 3B pipe is cheaper than 5B riser pipe that is a base condition. The results are that fuel dryout is happen by 1.8MW channel power on 3B, but is not happen on 5B riser pipe. (2)The influence of the riser pipe number reduction and the riser pipe diameter change. The case of connection 2 pressure tubes by Y piece pipe is analyzed. In this case, the riser pipe number is half. The cases that riser pipe is 5B and 4B are analyzed. The results are as below. (a)Natural circulation flow lower by riser pipe number is half. (b)Fuel dryout is happen by 1.8MW channel power on 4B, but is not happen on 5B. (3)The influence of the middle position header connection and the riser pipe diameter change, The case of connection 50 pressure tubes by the middle position header is analysed. The cases that riser pipe is 24B and 32B are analyzed. The results are as below. (a)In 2 cases, natural circulation flow lower as compared with base case. (b)In 2 cases, fuel dryout are not happen by 1.8MW channel power. (4)The influence of pressure tube diameter. The case of pressure tube diameter widening is analyzed. So, the pressure loss of pressure tube domain govern the flow. (a)Natural circulation flow increase by pressure tube diameter widening. (b)The flow swing is by pressure tube diameter widening. (c)In analysis cases, fuel dryout is not happen. We get 1.8MW channel power on the condition that riser pipe is 4B, riser pipe is connected by Y piece pipe, pressure tube diameter is 122.0mm.
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PNC TJ9381 93-001, 158 Pages, 1993/02
Present nuclear power reactor adopts a forced circulation system. But, the natural circulation studies for light water reactor are recently preceeding. So, on purpose to examine possibility of ATR natural circulation reactor in 1000Mwt class, we evaluated the natural flow and core cooling characteristic for ATR. In this study, the sensitivity analyses for the natural circulation characteristic by change inlet pipe diameter, outlet pipe diameter, core length, and downcomer pipe height were executed. Then the sensitivities are as follows. (1)Influence of inlet pipe diameter. From analyses of the case which was executed using 3B as inlet pipe diameter, against using 2B in the base case, it was clarified that channel flow of the case using 2B is more stable than that of the another. (2)Influence of outlet pipe diameter. From analyses of the cases which were executed using 4B and 5B as outlet pipe diameter, against using 3B in the base cases, it was clarified that the cases using pipes of a large diameter have more natural flow than the other cases, because of decreasing pressure loss at outlet pipes. (3)Influence of core length. From analyses of the cases which were executed using 3.2m and 2.7m as core length, against using 3.7m in the base case, it was clarified that the cases using short core length have more natural flow than the other cases, because of decreasing pressure loss at the core. (4)Influence of downcomer height. From analyses of the cases which were executed using 20m and 30m as downcomer against using 15m in the base case, it was clarified that the cases using high downcomer height have more natural flow than the other cases, because of increasing driving head which is the diferential pressure between the core and the downcomer. And, from the analyses results of (1) to (4), it was crarified that the item of the most largest sensitivity was downcomer height. And then, using the combination which have most natural circulation flows for ...
