| Contents Notes |
"On July 31, 1976, an 80-gallon radioactive waste package was retrieved from a low-level radioactive waste dumpsite in the Atlantic, located at a depth of 2800 meters, 120 miles (190 Km) east of the Maryland-Delaware coast at coordinates 38À30'N, 72À06'W. This was the first such recovery of a radioactive waste package from an ocean dumpsite and was conducted by the EPA Office of Radiation Programs. The drum was transported to the Brookhaven National Laboratory where container corrosion, and matrix leach rate and degradation rate analyses were conducted. The drum was dumped approximately 15 years prior to recovery and was found to contain a sealed steel vessel containing some liquid and would filter assemblies. The integrity of the concrete matrix has not degraded appreciably, and it is estimated that in the ocean dumpsite recovery environment it would require a minimum of 300 years before the concrete wast form would lose its integrity and provide no barrier to radioactivity release. The concrete waste form contained cesium-134, cesium-137, and cobalt-60 in both the concrete matrix and the inner steel vessel. The inner steel vessel did not leak; hence, the radioisotopes were contained. The estimated annual rate of leaching of the cesium-137 radioisotope measured in the concrete matrix was 3.7% per year. Corrosion attack on the metal container varied between the upper portion of the drum exposed to ocean water, and the lower portion of the drum exposed to sediment. General thinning attack appears to be most important corrosion process. It is estimated that an 18 gauge mild steel drum in this ocean dumpsite would require 25-37 years before corrosion would cause the metal container to lose its effectiveness as a barrier to radioactivity migration." |
