Technical complements: How are the canisters transported to Japan?

The TN 28 VT transport cask designed by the French company Transnucléaire, subsidiary of the COGEMA Group, is used to transport the vitrified residues from France to Japan.

OUTLINE OF TN 28 VT

Technical drawing of the TN 28 VT transport cask

TN 28 VT transport cask

TN 28 VT transport cask at Cherbourg port

Cogema train terminal at Valognes, Manche (France)

Cherbourg port Pier crane

Mutsu ogawara port aomori prefecture (Japan)

Technical description of a PNTL vessel

Safety features of a pntl vessel

In the 1970's BNFL decided to develop a design for purpose-built vessels for nuclear transport which provided enhanced protection for the ships and crews, so increasing the safety and reliability of transportation operations. Following wide consultation with Lloyds of London, The Salvage Association and leading salvage companies and as a result of Japanese standards developed at the same time, today's PNTL fleet was constructed.

Since this time extra equipment has been added in line with technological developments and operating experience to maintain high standards of operational safety.

The present PNTL fleet consists of 5 vessels, Pacific Swan (1979), Pacific Crane (1980), Pacific Teal (1982), Pacific Sandpiper (1985) and Pacific Pintail (1987). They are all registered in the UK.

The basic design of the PNTL ships is a double hull configuration with impact resistant structures between the hulls and with duplication and separation of all the essential systems to provide high reliability and accident survivability. This means that if any important system fails during a voyage, either due to mechanical failure or as a result of an accident, there is always a back-up system ready to be brought into operation.

PNTL's vessels have a number of advanced safety features. These include:

• Double hull to withstand damage and remain afloat
  These are designed to withstand a severe collision with a much larger vessel without penetrating the inner hull. The double hull structure extends over two-fifths of the width of the vessel, effectively making it "a ship within a ship" and the area between the hulls is reinforced for the length of the hold area with 20 mm thick horizontal steel plates. The inner shell embracing the cargo space is formed by watertight longitudinal and transverse bulkheads.
• Enhanced buoyancy
  The vessel is subdivided into numerous watertight compartments as a result of which a number of the holds and machinery spaces could be completely flooded with the vessel remaining afloat in a stable attitude. The sub-division of the hull is preserved by the use of watertight doors.
• Duplicated navigation, communication, electrical and cooling systems
  These are designed so that in the event of damage or mechanical failure in any part of the ship all essential systems will be able to continue functioning. This includes the duplicated routing of power supply cables for all these systems along both sides of the ship to prevent damage in one area severing supplies and considerable redundancy in power supplies.
  In addition to the main alternators situated aft, there are two additional alternators situated forward which are capable of supplying all the ship's main power. There is also an emergency alternator, which starts automatically in the event of a main power failure, capable of supplying all essential functions, such as navigational equipment, lights, steering equipment, fire fighting systems, etc.
• Satellite Navigation and Tracking
  The ship is fitted with five separate navigation systems including satellite navigation. Automatic position heading and speed reports are transmitted by the ship every two hours without intervention by the crew. These are monitored at the Ship Report Centre at Barrow in the UK.
• Additional Fire Detection and Fire Fighting Systems
  In addition to statutory requirements the ships are fitted with extensive fire detection and fire fighting systems, including the ability to flood the holds and machinery spaces with fire suppressant gases and the cargo holds with water. The ship's fire detection system covers every space on the ship and the pumps which supply fire fighting and spray systems are also duplicated, being located in both the main engine room and the forward machinery space. The ship would remain afloat, stable and able to function if all of the cargo holds were flooded at the same time.
• Twin Propellers and Engines
  Conventional ships of this size are normally single engine, single rudder configurations but for the purpose of reliability all the ships have twin propellers and engines which operate entirely independently. In practice, one engine can be stopped and declutched while the ship maintains progress at about 10 knots on the other engine.
• Bow thruster
  All the ships are fitted with bow thrusters to provide greater manoeuvrability at slow speeds.
• Radiation Monitoring Systems
  As well as a daily routine of manual radiation monitoring all the ships are fitted with fixed radiation monitors which are linked to a monitoring point outside the holds and to an alarm system on the bridge.

Drawing of a PNTL purpose-built ship

A PNTL ship at sea