No abstract

For sea disposal of the low-level radioactive wastes, high hydrostatic pressure tests on the full size (200 /) multi-stage type packages were carried out in a pressure vessel. Using the data obtained, ingress of water through leak path was simulated by a computer analysis.In order to confirm the above results, a demonstration test on integrity of the package in deepsea (5,000 m depth) was carried out at 90 miles off Nojimazaki, Chiba-ken (143.10'E, 33.50'N) by hanging the package down to 5,000 m depth. In these tests, no appreciable damage of the packages was observed which could give rise to controversy in safety.

Abstract:In the consideration of safety it is required that packages containing radioactive wastes when dumped at sea should keep their integrity and retain their contents until they reach the seabed. Packages containing simulated radioactive wastes (non-radioactive) were tested by a free-fall method at depths ca. 4, 300 m in an area for dumping industrial waste off Shikoku Island. Since the weight of the largest package was 4,300kg, special attention was paid to the connection of a buoyancy system with mooring rope. Descent and ascent velocities of the free-fall system were calculated prior to the experiment. A free-fall experiment with an extremely heavy object, heavier than ever previously reported, was accomplished without trouble by using the free-fall system. Recovery of a camera, flash-light, and other components was successful in each of the three experiments. Successive photographing of the package during descent was made and its integrity was observed using the photographs taken by the recovered camera. The packages remained intact during descent and at least for a short time after arrival on the seabed.

No abstract