Tartu firm patented tech to scan Paldiski former nuclear sub reactor site

Site of the former nuclear reactors at Paldiski.
Site of the former nuclear reactors at Paldiski. Source: ERR

Tartu-based firm GScan has developed tech which will allow for building up a three-dimensional image of the site of a former nuclear reactor, which was installed in the port city of Paldiski during the Soviet era.

GScan has patented the tech, which itself uses naturally-occurring muon radiation, in order to scan larger objects, which should provide the first opportunity to truly ascertain what was left when the former reactor was concreted over.

The reactor was not used in a power station as such but instead in a training version of a nuclear submarine,

Company director Andi Hektor told ETV news show "Aktuaalne kaamera" (AK) that muons are: "A type of [sub-atomic] particle that can pass through large objects like buildings and bridges, but at the same time, their incidence can be measured quite easily. Our tech permits us to do this in a unique way, then subsequently put together the picture of the object through which they have passed."

On decommissioning the facility, the Soviet authorities removed the fuel rods from the 50 meter long, 8 meter in diameter training sub's hull, and the concreted the entire hull over. At the same time, it is not known what else may have been discarded into the wet concrete, and given the track record of the Soviet military in particular during the occupation of Estonia – pumping large quantities of aviation fuel into the ground is but one example – and in the light of the 1986 explosion at the Chernobyl nuclear power station, getting a clearer picture of the Paldiski site is desirable.

The process will take several weeks, however, Hektor said.

"Naturally, we haven't found anything just yet. In order to put together a 3D image, a certain amount of data must be collected, and we will be able to produce a somewhat hazy image perhaps after a month," adding that hazardous items of some description, including radioactive metal debris, are known to be present.

The site hosted two reactors in fact – the entire measurement reading process will take around four months.

The project is GScan's first commercial venture, and will be followed by readings to be taken on a bridge structure in the U.K.

From the late 1950s as the Cold War was entering its peak, through to 1997 when the Soviet Union's successor state, the Russian Federation, took on the inventory, just under 250 nuclear submarines were constructed at just four shipyards in St.Petersburg (then Leningrad), Nizhny Novgorod, Severodvinsk and Amurskiy Zavod – more than the total output of all other nations which have produced completed nuclear submarines, combined (namely the U.S., the U.K., France, China and India).

Paldiski became a Soviet Navy nuclear submarine training center in 1962, with the construction of a facility known locally as the pentagon, decommissioned in 1994 and demolished in 2007. At its peak, the pentagon employed around 16,000 personnel across the two reactors (rated at 70MW and 90 MW) and was in fact the largest facility of its kind in the Soviet Union. As a result of its highly sensitive nature, the whole of Paldiski was a closed town.

The term nuclear submarine does not refer to the vessel's armaments systems (though this may or may not include nuclear missiles), but rather to the vessel's power plant; a nuclear reactor-driven sub has several advantages over its diesel-electric counterparts, including having no need to regularly surface.

Other submarine facilities operating during the Soviet occupation of Estonia included a submarine pen also existed at Loksa, Lääne-Viru County, and a base at Hara, Harju County, which was used for highly classified demagnitization purposes, as a means of avoiding detection. The harbor is open to the public.

Estonia has no nuclear reactor of any kind in operation or under construction at present, though planning for a potential small nuclear reactor, in order to generate electricity, is in its early phases.


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Editor: Andrew Whyte,

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