Page 320 - Practical Ship Design

278 Chapter 9

9.4.2 Nuclear power ships
Nuclear power has been used extensively in US, British and USSR submarines, in
a few US aircraft carriers and in a number of USSR ice breakers. In each of these
uses, nuclear power has particular advantages and all these installations appear to
have been technically successful. Costs have, of course, hardly mattered in these
uses and in most of them there really was no other technical solution giving
anything like the same performance.
The use of nuclear power in merchant ships reached the stage of three different
prototype vessels and was undoubtedly shown by these to be technically feasible. It
could even be economically attractive, assuming a high oil price of the order of that
prevailing in 1980, although it would be necessary to build a considerable number of
ships to a standard design to defray the very high development costs which would be
involved. However, the resistance which the prototype vessels met from environ-
mental groups worldwide was so great that their entry into ports was denied and the
ships were laid up without completing their planned trial periods.
In all the nuclear installations to date, the nuclear reactor acts as a boiler
supplying steam, generally at moderate steam conditions, to one or more steam
turbines.

9.5 AUXILIARY POWER

9.5. I Electricity generation
Every ship has many systems, equipment and machinery requiring auxiliary power.
The requirement is generally for electrical energy, but heat energy can also be used
directly via steam, hot-water or hot-oil systems, whilst mechanical energy is used
directly to drive pumps on oil tankers and dredgers.
In the interest of economy, a designer should start by looking for ways of
minimising the electrical power and heat demands. The next priority is to find
ways of meeting these demands with the minimum consumption of the cheapest
fuel, taking into account in doing so the associated capital and maintenance costs
and, of course, also keeping a wary eye on the system complexity.

9.5.2 Waste heat utilisation
In many merchant ships, the amount of waste heat available from exhaust gas is
such that there is no great need to economise in “other heat” demands, but on the
other hand the amount is insufficient to justify its use for generating electricity.
In other cases, notably on large bulk carriers, the exhaust waste heat is sufficient
to make its use in generating electricity worthwhile as it can meet the comparatively