Термодинамічні аспекти поведінки негерметичного твела під час роботи реакторної установки на потужності
The challenge of operation for fuel assemblies with failed fuel rods is that during power maneuvering there is a rapid increase in the activity of some gaseous radionuclides in the coolant. Moreover, such increase is observed both during power increase and during its decrease. Activity increase of s...
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| Видавець: | State Scientific and Technical Center for Nuclear and Radiation Safety |
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| Дата: | 2024 |
| Автори: | , , , , , |
| Формат: | Стаття |
| Мова: | Ukrainian |
| Опубліковано: |
State Scientific and Technical Center for Nuclear and Radiation Safety
2024
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| Онлайн доступ: | https://nuclear-journal.com/index.php/journal/article/view/1120 |
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Репозиторії
Nuclear and Radiation Safety| Резюме: | The challenge of operation for fuel assemblies with failed fuel rods is that during power maneuvering there is a rapid increase in the activity of some gaseous radionuclides in the coolant. Moreover, such increase is observed both during power increase and during its decrease. Activity increase of some gaseous radionuclides in the coolant during power increase is explained by temperature increase under fuel cladding, which causes pressure increase and, as a consequence, release of a part of the gas gap into the coolant. Activity increase of gaseous radionuclides in the coolant during power decrease is commonly referred to as the spike effect. There are some explanations of this phenomenon in the scientific literature available today, which associate the spike effect either to pressure decrease in the coolant or to the opening of pores on fuel surface due to the deformation of pellets.
Taking into account the fact that power maneuvering becomes actually a routine operation and additional radiation impact associated with maneuvering due to the presence of failed fuel rods in the core is not accurately studied, the causes and essence of the spike effect have gained new urgency. Therefore, the authors of the article returned to the consideration of this phenomenon. The article offers an explanation of the spike effect from the viewpoint of thermodynamics on the basis of a very simplified but understandable qualitative analysis of the basic thermodynamic processes that occur in nuclear fuel (fuel rod) when reactor power is reduced. |
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