«Cliff Edge Effects» in Safety Justification and Operation of NPP Units

Q4 Energy

Izvestiya Wysshikh Uchebnykh Zawedeniy, Yadernaya Energetika Pub Date : 2022-01-01 DOI:10.26583/npe.2022.1.08

Valentin Mikhailovich Makhin, Anatoly Konstantinovich Podshibyakin

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Abstract

The authors consider phenomena that have signs of ‘cliff edge effects’ according to the definitions of the IAEA and NP-001-15: (1) degradation of the protective barrier (fuel rod claddings in surface boiling mode with the deposition of impurities and borates on their surface and heating of the claddings) and (2) departure from nucleate boiling (DNB) on the fuel rod claddings. Despite the fact that the first phenomenon was previously unknown, the safety of the power unit is ensured by the decisions adopted in the project. The DNB was studied and measures were taken in the project to prevent it under normal operating conditions and anticipated operational occurrences. The protection against the DNB is also obviously ensured by reducing the reactor power due to the control systems and reactor scram. These phenomena do not reach the state of ‘cliff edge effects’ (according to the terminology of the IAEA and federal NPs of the Russian Federation) and are prevented at the initial stages. For a small-size reactor using dispersive fuel, it is possible to provide self-protection against the DNB, namely, due to partial washout of the fuel with the insertion of negative reactivity, followed by a decrease in power and termination of the crisis.

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核电厂安全论证与运行中的“悬崖效应”

根据IAEA和NP-001-15的定义，作者考虑了具有“悬崖边缘效应”迹象的现象:(1)保护屏障的退化(表面沸腾模式的燃料棒包壳，其表面有杂质和硼酸盐的沉积和包壳的加热)和(2)燃料棒包壳上的核沸腾(DNB)偏离。尽管第一种现象以前是未知的，但该项目所采取的决定确保了动力装置的安全。对DNB进行了研究，并在项目中采取了措施，以防止在正常操作条件和预期的操作事故下发生DNB。由于控制系统和反应堆停堆，减少反应堆功率显然也保证了对DNB的保护。这些现象还没有达到“悬崖效应”的程度(根据原子能机构和俄罗斯联邦联邦国家行动计划的术语)，并在最初阶段加以预防。对于使用分散型燃料的小型反应堆，有可能提供针对DNB的自我保护，即由于插入负反应性导致燃料的部分冲洗，随后功率下降并终止危机。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Izvestiya Wysshikh Uchebnykh Zawedeniy, Yadernaya Energetika Energy-Nuclear Energy and Engineering

CiteScore

0.40

自引率

0.00%

发文量

期刊介绍： The scientific journal Izvestiya Wysshikh Uchebnykh Zawedeniy, Yadernaya Energetika is included in the Scopus database. Publisher country is RU. The main subject areas of published articles are Nuclear Energy and Engineering, Физика, Приборостроение, метрология и информационно-измерительные приборы и системы, Информатика, вычислительная техника и управление, Энергетика. Before sending a scientific article, we recommend you to read the section For authors. This will allow you to prepare an article better for publication, to make it more interesting for the readers and useful for the scientific community. By following these steps, you will greatly increase the likelihood of your scientific article publishing in journals included in international citation systems (e.g., Scopus). Then you may choose a different journal, select the journal included to list of SAC Russia journal list, or send your scientific work for review and publication.