A total of 97,672 drums of low-level radioactive waste solidification were stored from the opening of Lanyu Storage Site in 1982 to 1996, when it stopped accepting. Facing the Western Pacific Ocean, Lanyu often experiences high temperature, salinity, and humidity. Over 30 years, corrosion and damage occurred on the waste drums that were stored in the early days. In order to improve the storage safety of waste drums, Taiwan Power Company has started a comprehensive examination and repacking program since December 2007. It has divided waste drums into four categories for examination.
The examination and repacking program of waste drums in Lanyu Storage Site was completed on November 26, 2011. Since there were 2,410 severely damaged drums in category 4, the volume increased by about 2.1 times after crushing and solidification, resulting in an increase in the number of waste drums by about 2,605. Therefore, there are a total of 100,277 waste drums after the examination and repacking program.
Implementation Plan for Enhancing the Operational Safety of the Lanyu Storage Site (https://www.aec.gov.tw/webpage/control/waste/files/index_25_3-01.pdf) aims to divide 55-gallon waste drums of categories 1, 2, and 4 after examination in the trench into A, B, C, and C+ according to the concentration of nuclide contained. Then, put them into ""3×4 repacking containers" separately to increase the storage durability of 55-gallon waste drums and improve the operational safety of the Storage Site. At the same time, this can reduce the processing time for future relocation.
“3×4 repacking container”:
The size of the container:
Length 284.7cm ×Width 219.7cm ×Height 109cm (contains up to 12 55-gallon drums)
For a “3×4 repacking container”, the film thickness of hot-dip galvanization is no less than 80μm. The density of zinc is 7.14g/cm3, and the amount of zinc per unit area is 571g/m2. According to the analysis conducted by Taiwan Power Research Institute, the corrosion rate for test pieces of hot-dip galvanization placed in the trenches of the Lanyu Storage Site from 1996 to 2000 is 0.51 μm/year (3.64g/m²/year), which can be maintained for at least 40 years.
A total of 35,867 55-gallon waste drums must be placed in "3 ×4refill containers". Besides using around 250 "3×4 repacking containers" in the site, another 2,740 "3×4 repacking containers" must be produced.
The production process is in accordance with the third-level quality audit of Taiwan Power Company. Meanwhile, the AEC also sent personnel to carry out project inspections (https://www.aec.gov.tw/webpage/control/waste/files/index_25_3-02.pdf) to control the process quality.