Eighteen of 70 barrels of low- and intermediate-level radwaste at cavern 4 of Brunsbuettel nuclear power plant in Germany show so much corrosion that special handling procedures are warranted, according to a report from utility Vattenfall.

It has completed a visual inspection of the cavern and discussed possible next steps with the nuclear regulator and standards body Tuev Nord.

"Overall, the result is in line with our expectations," says Pieter Wasmuth, managing director of Vattenfall Europe Nuclear Energy Communications GmbH. "The caverns are safe, they are in the shielded area of the nuclear power plant. There have been no health hazards during the inspection, for either staff or for the population. The gauges in the region of cavity 4 have shown no abnormalities."

"Neither the caverns nor the barrels were intended for such a long storage. The barrels were originally supposed to already be placed in the nationwide repository for low and intermediate level radioactive waste Konrad by the mid-1990s," Wasmuth added. According to Vattenfall, the German government expects Konrad to be commissioned 2021-2025.

Affected barrels, about 1m tall and half a metre in diameter, will be transported in a secured fashion inside a barrel grab bag, according to an idea developed by Vattenfall.

"Our goal is to clear out the cavern and transfer the contents of the barrels into containers suitable for disposal in Konrad," said Wasmuth. Emptying the barrels into new containers, cast-iron GNS yellow boxes, and then grouting them, requires consent from German regulator and the Federal Office for Radiation Protection (BfS), which is expected to take nine months. In the meantime, Vattenfall said it would inspect caverns 1-3, in consultation with the regulator.

Because a supply of GNS yellow boxes would not be available until next year, Vattenfall is considering filling other cast-iron containers originally intended to store other waste.

The next cavern inspection is scheduled for June 2014. Caverns 5 and 6 contain radwaste barrels and other radwaste, and so must be inspected separately.

In total the six caverns contain 631 barrels of low- and intermediate-level radwaste. The drums contain waste from wastewater treatment or from process circuits. They include filter resins, evaporator concentrates or mixed waste including cloth and construction debris. Cavern 5 includes 21 barrels of waste from a fuel campaign from the Belgian Mol reactor.

Infographic of Vattenfall's recovery plan, translated from the original German by NEI magazine

Infographic of Vattenfall’s recovery plan, translated from the original German by NEI magazine