Close Overlay
Research & Development

Research & Development

Salvage operations using freezing
Project "Thunersee"

Media presentation 12th March 2004Hotel “Bern“ Switzerland

The Project Team


  • Professional commercial diving company
  • Diving work on oil drilling and production platforms
  • Salvage operations in Germany and abroad
  • Diving and compressed air work in shield tunnelling projects
  • Rehabilitation of dams and power stations
  • Diving in nuclear power stations

Kirchner Maschinen- und Apparatebau GmbH

  • Mechanical engineering and plant construction
  • Special machines and process plants, including measurement and control technology
  • Flotation and filtration plants, scrapers, inclined clarifiers, sorting and handling systems
  • Maintenance of paper processing machines, hydraulic equipment, extrusion presses...

Tienken Ingenieurbüro und aukos GmbH

  • Automation technology
  • Circuit diagrams, machinery and plant wiring, programming, visualisation,
  • Controls for assembly lines, straightening lines for sheet steel, water and waster water purification plants, boiler controls
  • Sea water freezing units

Technological status

  • Conventional methods of lifting
    • Standard ship or pontoon mounted lifting gear is used
    • Divers attach lifting gear and floaters
    • Divers close and seal all cavities
    • The object is pumped out to add buoyancy in shallow water
    • Divers attach additional floatation aids; appropriate mechanical aids are required
  • Limits and restrictions
    • Divers can only operate at certain depths and for specific amounts of time
    • Attaching the necessary hooks, lugs and salvage aids underwater is difficult and time-consuming
    • It is risky and virtually impossible to lift decaying and/or fragile objects without causing irreparable damage
    • Moving these objects through water and over land in an unprotected state is dangerous
  • The innovation
    • Submerged objects are frozen and then lifted with the aid of lifting gear or are brought to the surface by means of floaters
    • The object remains frozen throughout all further treatment and transportation
  • The advantages
    • Ice has a similar resistance to pressure to that of concrete
    • High tensile strength due to the ice encasement
    • Full surface force transmission, adheres to surfaces
    • Can be used at great depths
    • Stabilises damaged, fragile objects
    • The object is sealed and impervious to fluids
    • Environmentally friendly method
    • Hazardous goods, electronic components etc. are supercooled
    • Chemical reactions are decelerated
  • The theory
    • 1 kg steel, density 7.8 kg/dm³ (a cube with edges 5.04 cm in length)
    • How much ice is needed to lift this object?
      VIce = 8.718 dm³
      mIce = 7.846 kg
    • How much energy is required to create ice? (water temperature: 4°C, ice: -10°C)
      ∑ Q = 2930.5 kJ (0.814 kWh)
  • In Practice
    • Liquid nitrogen is used
    • Supercooling equipment is used
    • The object is completely encased, making it impervious to fluids
    • The object is stabilised
    • Secure transport
  • Summary
    • Generate a layer of ice that is thick enough (~20 cm)
    • In an acceptable period of time (~5…10 h)
    • The object is stabilised and frozen, and can then be securely salvaged
    • The amount of time, material and manpower required can be calculated in advance
    • No problems with waste disposal after salvaging


Explosive ordnance (ammunition)


TNT (trinitrotoluolene) is the most widely used explosive. It is used as an explosive charge in ammunition. TNT is chemically stable and fairly easy to handle. A detonator is needed to trigger TNT.

TNT is highly toxic: if absorbed through the skin, respiratory system or ingested it will cause toxic symptoms, e.g. bilious colics, liver damage (toxic jaundice); it can affect the blood count and cause cardiovascular disease and neurological disease, such as apathy or depression.

TNT is not particularly water soluble (approx. 130 mg/l); however, very small qualities in the magnitude of a few µg/l (micrograms per litre) will produce a toxic reaction.

Ecological toxicity: the lethal concentration of TNT for fish, "LC50 (fish)", is 0.8 g/m3 (grams per cubic metre).

The substances required to make TNT (particularly tolulolene) and the intermediate compounds mononitrotoluolene (MNT) and dinitrotoluolene (DNT) are also highly toxic.

TNT, contaminated forms of TNT, degradation products and metabolites always present a severe risk to the environment. Studies suggest that high concentrations of explosives may have a negative effect on the endocrine system, while extremely low concentrations do not present a substantial risk.

Chemical agents:


Tear gases:


Respiratory irritants:

diphenylchlorarsine (DA),
diphenylcyanarsine (DC),
adamsite (phenarsazinchloride)

Choking agents:


Blistering agents:

S-Lost (sulphur mustard),

Nerve agents:

Tabun (Gelan, Trilon 83)

Adverse effects:

Due to their specific chemical and physical properties, the most hazardous chemical agents are the highly stable, persistent chemical agents containing arsenic (DA, DC, Adamsite) and S-Lost in the form of viscous sulphur mustard. High concentrations of stable DA, DC, adamsite or viscous sulphur mustard are frequently found in the sediment in the immediate vicinity of sunken or submerged ordnance.

The crews of fishing vessels which operate in areas where ammunition and/or chemical warfare agents have been disposed of at sea are most at risk. There is a real risk that containers with chemical agents or explosive ordnance can get caught in the trawler nets and taken on board, thus exposing the crew to the danger of contamination with all ensuing health risks.

Many warfare agents degrade in water to less toxic and easily soluble compounds. However, viscous sulphur mustard can remain fully active for many years and will attack the skin; high local concentrations of arsenic compounds (DA, DC, Adamsite) can remain in the sediment and will bio-accumulate.


Incendiary agents and bombs:

Incendiary devices from the second world war contain phosphor. If the device container rusts right through, the phosphor can leak out and small lumps can be washed ashore. Once the phosphor is exposed to the air it can spontaneously combust.


Ordnance, warfare agents, chemical agents, damaged ammunition or production residues and waste from the production of ordnance remain hazardous for many years, contaminating the environment and bio-accumulating. If handled incorrectly ordnance can explode. If the ordnance containers, detonators or agent containers rust, the explosives, chemical and incendiary agents can leak out, thus posing a direct or indirect hazard to humans and the environment.


On-site disposal

On-site disposal

Safety containers

Warfare agent and ordnance container

On-site disposal unit


A specially reinforced muffle furnace Is used for thermal disposal.
The warfare agent and ordnance container is used as an intermediate storage facility.
Decommissioning takes place in the safety container.


Your contact person in the project team is:

Nordseetaucher GmbH
Claus Mayer
Bramkampweg 9

22949 Ammersbek / Hamburg
Tel.: +49 4102 23180;
Fax: +49 4102 231820;
Mobil: +49 173 6990120;

Nordseetaucher GmbH - | Kirchner Maschinen- und Apparatebau GmbH -  | Tienken Ingenieurbüro und aukos GmbH -