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Castor can rust: New facts bring more doubts

Nuclear Monitor Issue: 

(December 18, 1998) A document, published in a Berlin newspaper, sparked new controversy about nuclear transports in Germany. According to the Bundesanstalt für Materialforschung und -prüfung (BAM, Federal institute for material research and testing), it found water inside a groove of a Castor container. All precautions were taken during filling and drying of the container. As a result of these new revelations a ban on loading Castor casks is adviced.

(504.4965) WISE Amsterdam - In a letter to the German Ministry of Radiation Protection, BAM raises questions about the long time safety of the Castor type 440/84. They found water inside the primary sealing in the container, even after drying. This type of Castor is licensed to store fuel elements for 40 years in interim storage facilities at Ahaus, Gorleben and Lubmin (Greifswald).
The ministry is taking the outcome of the research very seriously. Due to the moisture found at a groove on the primary lid, rust inside the container is possible. The consequence is that the Castor can loosen. The Castors have to be absolutely airtight for all those years. In case of rust, this can no longer be guaranteed.
In the letter to the ministry, BAM speaks of a fundamental problem for all containers which are filled under water.
A few weeks earlier, on November 18, a test was conducted by a Castor-type 440/28. After a cold test, water was found inside the largest primary lid sealing material, although the drying procedure of the space between the primary and secondary lid was done according to all procedures.
Castor casks have two lids: a primary and secondary, with gas in overpressure in between the two (see drawing). When leaking is found in the interim storage facility, a third lid should be welded onto the cask and it should be removed to be repaired.

Moisture due to loading the casks under water is an old problem, known already in the 1980s. In Germany (as in the Netherlands), nuclear transports are still not allowed after outside contamination of Castors was revealed this spring.

On December 11, experts and regulators advised a total ban on loading of Castor casks. It was agreed on more research and tests. A ban to load Castor casks has not much consequences at the moment because of the general transport ban. However, if it is found that the Castor is loose, this would have enormous consequences for the red/green government. The concept of interim storage facilities on site or nearby reactor sites is totally based on storage in of fuel in Castor casks.

Sources: Die Tageszeitung (Germany), 5 & 12 December 1998
Contact: BI Ahaus, Po Box 1165, D-48661 Ahaus, Germany
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