Structural Analysis of a Nuclear Fuel Pool Steel Liner
Pirkkanen, Lauri (2018)
2018
Konetekniikka
Teknisten tieteiden tiedekunta - Faculty of Engineering Sciences
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Hyväksymispäivämäärä
2018-12-05
Julkaisun pysyvä osoite on
https://urn.fi/URN:NBN:fi:tty-201811062541
https://urn.fi/URN:NBN:fi:tty-201811062541
Tiivistelmä
This thesis looks into the structural behavior of a nuclear fuel pool steel liner under nor-mal and abnormal operating conditions. The pool liner is a welded sheet metal assembly which is supported by concrete embedded anchors and stressed by multiple diverse types of loads. The majority of the stresses are generated by the hydrostatic pressure and temperature of cooling water. Other, more insignificant loads, such as the shrinkage and creep of the concrete pool over time, may not be negligible in some cases but in this study, they have not been taken into account.
In the nuclear industry, the consequences of an unreliable component may cause severe production losses due to long repair times, so many precautions are taken to prevent un-intentional downtime. This necessity of high-level safety standards covers also the pool liner assembly and leads to the requirement that no cooling water leakage is acceptable through the weld seams or any other part for that matter. Hence, one of the objectives of this thesis is to find the most unreliable segments of the liner assembly and analyze its structural integrity. Possible leakages of the pools can be detected and located with leakage control system. Necessary water inventory for the safety related functions of the pools will be preserved with watertight pool liner and concrete structures.
The thesis is divided into three sections: The first part covers the standards and design guidelines which are being followed nowadays, when new nuclear power plants are built. These documents offer good comparison point for the analysis results. In the sec-ond part of the thesis, the theory and the background for the analysis is dealt with. This includes the introduction of the calculation model and explanation of the applied boundary conditions. The last part contains the analysis results and the discussion on the outcome relevancy.
The nuclear fuel pool and the steel liner analyzed in this thesis are from Olkiluoto nucle-ar power plant. There are two nearly identical reactor units, OL1 and OL2, so this study is applicable to both of them. The concrete pools of Olkiluoto plant have already been analyzed but the steel liners were not considered. This thesis continues that work and aims to a reasoned conclusion for the liner’s fail probability under different conditions.
In the nuclear industry, the consequences of an unreliable component may cause severe production losses due to long repair times, so many precautions are taken to prevent un-intentional downtime. This necessity of high-level safety standards covers also the pool liner assembly and leads to the requirement that no cooling water leakage is acceptable through the weld seams or any other part for that matter. Hence, one of the objectives of this thesis is to find the most unreliable segments of the liner assembly and analyze its structural integrity. Possible leakages of the pools can be detected and located with leakage control system. Necessary water inventory for the safety related functions of the pools will be preserved with watertight pool liner and concrete structures.
The thesis is divided into three sections: The first part covers the standards and design guidelines which are being followed nowadays, when new nuclear power plants are built. These documents offer good comparison point for the analysis results. In the sec-ond part of the thesis, the theory and the background for the analysis is dealt with. This includes the introduction of the calculation model and explanation of the applied boundary conditions. The last part contains the analysis results and the discussion on the outcome relevancy.
The nuclear fuel pool and the steel liner analyzed in this thesis are from Olkiluoto nucle-ar power plant. There are two nearly identical reactor units, OL1 and OL2, so this study is applicable to both of them. The concrete pools of Olkiluoto plant have already been analyzed but the steel liners were not considered. This thesis continues that work and aims to a reasoned conclusion for the liner’s fail probability under different conditions.