{"title":"Study on transient characteristics for bypass valve regulation and load rejection of microreactor with helium Brayton cycle","authors":"Xuyao Geng, Wenkui Ma, Jie Wang","doi":"10.1016/j.pnucene.2024.105527","DOIUrl":null,"url":null,"abstract":"<div><div>Microreactors coupled with closed helium Brayton cycle (MR-CBC) can be used as mobile nuclear power source and have a wide range of application prospects. The power regulation methods and accident control measures are the key to safe and efficient operation of MR-CBC system. In this paper, the dynamic model of MR-CBC system is established, the characteristics of MR-CBC under bypass valve regulation method and load rejection event are analyzed. The results indicate that bypass valve is a fast regulating device. The power distribution of MR-CBC can be changed significantly and quickly with little change in core power. This regulation method changes the flow rate and operating performance of compressor and turbine, resulting in an increase in the proportion of compressor power consumption, a rapid reduction in generator power, and a significant drop in system efficiency. After losing the generator load, if no protection measures are taken, the shaft speed will increase rapidly and exceed the designed limit value in a short time. Due to the short time left for the protection system to act, it is necessary to prepare responsive control methods, such as bypass valve regulation. Finally, the transient characteristics of load rejection under the control of bypass valve are analyzed. Opening the bypass valve can avoid overspeed of the shaft. When the valve opening action is assumed to be completed in 0.25s, at least 1.37 kg/s of bypass flow rate is required to keep the rotational speed below designed limit value. The simulation results demonstrate the basic characteristics of power regulation and mitigation measures, and provide a reference for the design and operation of MR-CBC.</div></div>","PeriodicalId":20617,"journal":{"name":"Progress in Nuclear Energy","volume":"179 ","pages":"Article 105527"},"PeriodicalIF":3.3000,"publicationDate":"2024-11-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Progress in Nuclear Energy","FirstCategoryId":"5","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/S0149197024004773","RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"NUCLEAR SCIENCE & TECHNOLOGY","Score":null,"Total":0}
引用次数: 0
Abstract
Microreactors coupled with closed helium Brayton cycle (MR-CBC) can be used as mobile nuclear power source and have a wide range of application prospects. The power regulation methods and accident control measures are the key to safe and efficient operation of MR-CBC system. In this paper, the dynamic model of MR-CBC system is established, the characteristics of MR-CBC under bypass valve regulation method and load rejection event are analyzed. The results indicate that bypass valve is a fast regulating device. The power distribution of MR-CBC can be changed significantly and quickly with little change in core power. This regulation method changes the flow rate and operating performance of compressor and turbine, resulting in an increase in the proportion of compressor power consumption, a rapid reduction in generator power, and a significant drop in system efficiency. After losing the generator load, if no protection measures are taken, the shaft speed will increase rapidly and exceed the designed limit value in a short time. Due to the short time left for the protection system to act, it is necessary to prepare responsive control methods, such as bypass valve regulation. Finally, the transient characteristics of load rejection under the control of bypass valve are analyzed. Opening the bypass valve can avoid overspeed of the shaft. When the valve opening action is assumed to be completed in 0.25s, at least 1.37 kg/s of bypass flow rate is required to keep the rotational speed below designed limit value. The simulation results demonstrate the basic characteristics of power regulation and mitigation measures, and provide a reference for the design and operation of MR-CBC.
期刊介绍：
Progress in Nuclear Energy is an international review journal covering all aspects of nuclear science and engineering. In keeping with the maturity of nuclear power, articles on safety, siting and environmental problems are encouraged, as are those associated with economics and fuel management. However, basic physics and engineering will remain an important aspect of the editorial policy. Articles published are either of a review nature or present new material in more depth. They are aimed at researchers and technically-oriented managers working in the nuclear energy field.
Please note the following:
1) PNE seeks high quality research papers which are medium to long in length. Short research papers should be submitted to the journal Annals in Nuclear Energy.
2) PNE reserves the right to reject papers which are based solely on routine application of computer codes used to produce reactor designs or explain existing reactor phenomena. Such papers, although worthy, are best left as laboratory reports whereas Progress in Nuclear Energy seeks papers of originality, which are archival in nature, in the fields of mathematical and experimental nuclear technology, including fission, fusion (blanket physics, radiation damage), safety, materials aspects, economics, etc.
3) Review papers, which may occasionally be invited, are particularly sought by the journal in these fields.
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