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Rolling Test Simulating Sea Transport of Spent Nuclear Fuel
p.165
Currently, the development of evaluation technology for vibration and shock loads transmitted to spent nuclear fuel and structural integrity of spent nuclear fuel under normal conditions of transport is progressing in Korea by the present authors. Road transportation tests using surrogate spent nuclear fuel were performed in September, 2020 using a test model of KORAD-21 transportation cask and sea transportation tests were conducted from September 30 to October 4, 2021. Finally, the shake table tests and rolling test were conducted from October 31 to November 2, 2022. As a result of the sea transportation test data analysis, an impact load resulting from the collision of objects was measured on fuel rods of a surrogate spent nuclear fuel assemblies during the rolling test was observed. Excessive rolling motion occurred on the ship during the rolling test, causing the surrogate spent nuclear fuel assemblies to slip and collide with the canister. To analyze under which conditions such impact loads occur and whether this event is possible under normal conditions of transport of spent nuclear fuel, a test was designed to simulate the rolling test in sea transportation and was performed. The rolling test was conducted on ACE7 and PLUS7 assemblies, respectively, varying the rolling angle and rolling frequency to determine at which angles and frequencies the assemblies experienced slippage. According to the test results, slippage of the used nuclear fuel assemblies can occur due to rolling motion at angles of approximately 14° or higher, leading to the possibility of generating impact loads. It was observed that the rolling angle is a more major factor for slippage than the rolling frequency. This exceeds the conditions under which a vessel can be permitted to depart for coastal navigation, thus it is considered to deviate from the normal conditions of transport of spent nuclear fuel. Therefore, it is not necessary to consider such loads for evaluating the integrity of spent nuclear fuel during normal transportation conditions.
