NUCRUS96.402A Safety report & environment

From 1962 to 1985 the Lepse was used as a service vessel for replacing and storing spent fuel assemblies from three nuclear powered icebreakers: Lenin, Arktika and Sibir. During that period 645 spent fuel assemblies were accumulated aboard, located in two storage containers.

In 1967, fuel elements from the Lenin, which had been damaged during a loss-of-coolant accident (LOCA), were transferred to Lepse. These elements had swollen and were overheated and distorted during the accident, and have been partially forced into the channels, or emplaced at random in the larger channels called caissons. In addition to the spent fuel, there are a number of tanks for liquid radioactive waste and casks for solid radioactive waste.

The Lepse was constructed in 1934-1936, sunk in 1941, salvaged after the war and then modified for nuclear service purposes. It is in a bad condition, heavily corroded, highly radioactive and contaminated, containing a subtotal of 750000 Ci activity in fuel elements. This constitutes, as it is now, a major ticking, floating threat to the environment. Without urgent remediation measures the vessel might constitute a source of an extensive radioactive release and contamination catastrophe. The JSC Iceberg in St. Petersburg, later to become the subcontractor, was the ship builder. In early 1990s it received an order from Murmansk Shipping Company (MSCO) to make a feasibility study what to do with the Lepse.
The first phase was completed with several Russian institutes, but then the project was ended.

The Lepse Project (De-fuelling) in total comprises of 10 stages, called Work Plans. A first TACIS project (R4.08/93-Preparatory Investigation and Engineering Concept for Remediation at the Lepse Floating Base) covered already a part of the work to be done at the Lepse.

The present project covers Work Plan (WP) 4.
The objective of this WP 4 is to produce safety and environmental impact documentation for review by Gosatomnadsor in order to demonstrate that the de-fuelling can be carried out safely.

The project has produced separate reports for each of the work packages as per TOR. Final Report summed up the findings and included recommendations for the best option to remove the spent fuel from the Lepse.

In particular the following outputs were achieved:

• Safety and Environmental baseline Report;
• Environmental impact assessment Report;
• Preliminary safety analysis Report;
• Full safety analysis Report;
• Supporting documents.