Icebreaker – Student Digitalus

The world’s first nuclear icebreaker Lenin was in operation from 1959 until 1989. During that time, there have been two seriuos accidents onboard.

Bellona, 20/06-2003

The first nuclear propulsion unit (OK-150) on Lenin had three identical pressurised water reactors (PWR) with a maximum heat output of 90 MWt. The shaft power was 44 ,000 horsepower. Enriched uranium was used as fuel (the content of U-235 was equivalent 85 kg), and distillate water was used as a moderator and for heat transfer.The reactor core was 1.6 meters high and measured one meter in diameter.The core consisted of 7,704 fuel pins in 219 fuel assemblies.

There have been two accidents onboard the nuclear powered icebreaker Lenin. The first took place in February 1965, when Lenin was undergoing repairs and refuelling. The vessel sustained severe mechanical damages to the fuel assemblies, some of which were broken in two pieces, and were detected during the unloading of fuel from reactor number two. About 95 spent nuclear fuel assemblies were transferred to the nuclear service ship Lepse and unloading was halted after that.

After investigations as to why the spent nuclear fuel assemblies were deformed, it was established that the nuclear reactor operators had made an error that left the reactor core without cooling water. The partial deformation of the fuel assemblies had occurred due to overheating of the reactor core. About 60% of the assemblies were damaged.

The decision was made to unload the remaining 124 spent nuclear fuel assemblies together with the neutron absorbing rods and control grid.

A special cask was built onshore to implement this operation. A part of the reactor containing spent nuclear fuel (SNF) was placed into the cask and filled with furfurolbased solidifying matter. This cask was then stored for two years. In 1967, it was reloaded onto a pontoon, towed by a tug to the eastern coast of the Novaya Zemlya Archipelago and dumped in Tsivolki Bay.

The second accident aboard the Lenin took place in 1967, when the pipe system of the third circuit sprung a leak following the loading of fresh nuclear fuel. In this instance it was necessary to open the biological shield of the reactor compartment in order to locate the leakage. This protection was made of concrete mixed with metal shavings and it required the use of sledgehammers to break through the shield.This led to further damage of the reactor installation. Upon later examination, it became clear that it would be impossible to repair the damage incurred to the reactor installation by the sledghammers.

via Nuclear icebreaker Lenin – Bellona.

Two once-doomed California gray whales splashed with new life Wednesday as a pair of powerful Soviet icebreakers leading a massive rescue effort bashed through the last frozen barrier to their escape to the open sea.

“The whales are ready to get out of there,” said Cindy Lowry of Greenpeace as the two Soviet icebreaking ships cracked their way through the wall of ice at the edge of the arctic floe trapping the two young giant mammals.The whales, whose dramatic plight has set off an extravagant international rescue effort in the icy arctic, responded by vigorously swimming around their latest breathing hole.

“They are swimming up and down, really energetic,” Lowry said. She said the whales were “so active they were causing waves.”

The 20,241-pound Admiral Makarov, an 11-story icebreaker, and the 13,514-ton Vladimir Arseniev, an icebreaking cargo vessel flying an American flag alongside the hammer and sickle of the Soviet Union, began their attack on the icy ridge Tuesday afternoon.

They moved through the ice with such force that Lowry and another Greenpeace member keeping an all-night vigil beside the whales were afraid the huge icebreakers would plow right into them. But the threat turned out to be illusory.

The Soviets battered their way through the ice until 3 a.m. Alaska Daylight Time (5 a.m. MDT), getting within a half-mile to a mile of the whales.

Other rescue teams planned to fire up the 11-ton one-of-a-kind Archimedean screw tractor sometime after the Alaska sunrise to finish clearing a 16-foot-wide path for the whales to a 220-mile channel that will eventually take them to the open sea. The tractor’s pontoons are equipped with screw-like ridges that cut through the ice.

via SOVIET ICEBREAKERS CLOSE TO FREEING WHALES 2 GRAYS SPLASH WITH NEW LIFE AS MACHINES NEAR | Deseret News.