PLENTIFUL ENERGY

mistake let the power increase too far, and a portion of the football-sized core
melted. Radioactivity was detected in the control room. However, there was no
explosion, little damage outside the core, and no injuries. The reactor was cleaned
up, and in 1962, it became the first reactor ever to operate with a plutonium-fueled
core. It had served its purpose, however; EBR-II was coming into operation, and
EBR-I was officially shut down in December of 1963. It was designated a National
Historic Landmark by President Johnson in 1966. It can be visited today, and is
something of a tourist attraction. It is well worth a visit by anyone travelling
through eastern Idaho, perhaps on the way to Yellowstone or to Sun Valley.
EBR-I had been designed and built by a remarkably small number of engineers,
all young—in their twenties and thirties—and numbering about a dozen in all.
Several went on to lead the design and construction of EBR-II. But EBR-II was not
only the logical next step in the scale up of the breeder reactor, it was a trail-blazing
concept in itself. By the time it was shut down, for purely political reasons that
we‘ll go into later, it had forged a proud history, and it too had a large number of
firsts to its credit. It had incorporated many sound insights. One of the EBR-I young
engineers, Len Koch, became the Director of the EBR-II Project. In its early days
EBR-II was referred to as ―The Koch Machine,‖ which gives a hint as to the
importance of Koch to the project (as well as the pronunciation of the director‘s
name).
EBR-II was a scale up in power by a factor of sixty or so from EBR-I, but unlike
EBR-I, it was no test reactor. This was a power plant, and a complete one,
producing 20 MW of electricity, supplying power to the site and power for sale to
the appropriate utility. In a major first, it had an on-site facility for processing its
own spent fuel and fabricating new fuel with it. Processing was done without
delaying to allow the spent fuel to ―cool‖; the fuel was returned to the reactor ―hot,‖
highly radioactive. (Figure 1-11)
In another major first, EBR-II was given a ―pool configuration‖. In a pool, all the
radioactive components—the core itself, of course, but also the associated piping
and equipment that circulates sodium coolant through the core, and whose sodium
is radioactive as a result—are immersed in a large pool of sodium coolant. (Figure
1-12) This is easy to do with liquid sodium coolant because it needs no
pressurization (unlike in water-moderated reactors). It is liquid at low temperatures
(97 o C, about the boiling point of water) at room pressure, and stays liquid without
pressurization at temperatures far above operating temperatures of a reactor. No
pressure containment is needed for the primary tank; it can be made any size
desired. No need for the thick walls of the pressure vessels needed to hold water in
a liquid state at reactor operating temperatures in a water-cooled reactor. This
feature has many advantages, not least of which is that any leaks of sodium over the
reactor lifetime would not involve radioactive sodium. We‘ll go into that, and the
other advantages, in a later chapter.
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