Page 159 - ΝΑΥΤΙΚΑ ΧΡΟΝΙΚΑ - SEPT 2025

Sponsored by

IMO-IAEA framework, with an essential Not all ships are suitable for nuclear power. Large
role played by the IAEA Safety Standards, ocean-going containerships, tankers, bulk, and
to solve issues of proliferation and gas carriers are potential candidates due to the
licensing. Second, significant forward increased demand for bunkers, emissions reduction,
investments, which necessitate subsi- and bunkering operations requirements.
dies and state commitment, as well as
multi-layered insurance coverage with
extensive safety and environmental lia-
bility for radiation, will be required.
From a technical point of view, more
compact and lighter units and a fuel
cycle compatible with maritime trade
will be needed, which will have implica-
tions for operating costs and the long life
of reactor components (reflectors, heat
exchangers, attached pumps) – especially
those with very high design temperature.
Additional requirements include a core
material with consistent and verified
thermophysical properties, and a pres-
sure design that takes into account crit-
ical emergency zones in meters rather
than kilometres, ensuring the availability
of suitable nuclear assessment tools
for the proposed core designs.

What are the key technical challenges
in integrating nuclear power into
commercial vessels? of license holders, such as the US Nuclear
No significant technical challenges are Regulatory Commission (NRC), world-
foreseen; however, the hull and cargo wide that are familiar with nuclear ships’
area design needs to take into account port calls. This requires bilateral agree-
the peculiarity of the nuclear reactor and ments to be in place between recognised
the ancillary systems as, due to the radi- national licensing organisations. A world-
ation shielding of the core, the reactor wide common regulatory framework
becomes heavier, and, therefore requires developed within the framework of the
structural reinforcement and careful IMO and the IAEA will definitely expe-
study of trim and stability, as well as the dite nuclear ships allowed to call ports
dynamic effect of the ship’s motion on and cross the Suez and Panama canals.
the operation and fixing arrangements. There have been nuclear-powered naval
Moreover, core accessibility, depending and pilot ships (e.g., the NS “Savannah”
on individual core design, is vital in order and the “Otto Hahn”) that regularly
to minimise clashing in case of refuel- received permission to visit civilian ports;
ling or even removal of the unit. Finally, however, the frequency and operation
a minor technical inconvenience may of these ships maintained a low social
be the return of gas turbines in shipping provocation level.
following their gradual replacement by Free trading may need to be a more
internal combustion engines and the sub- A-to-B sailing based on long-term con-
sequent shortage of experienced crews. tracts between specialised ports certi-
fied for radiation exposure events.
To what extent are flag states and port
authorities prepared to handle How does nuclear propulsion affect ship
nuclear-powered ships? design, maintenance, and crew
In general, port authorities and flag training requirements?
states are poorly prepared to handle Retrofitting a nuclear reactor will be
nuclear-powered ships. more difficult since hull design may
There are, however, national regulators require restructuring.

September 2025 157