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Nigeria and nuclear fusion – Part 4

By J.K. Obatala   |   01 December 2016   |   2:02 am


Generally, light elements release energy when their nuclei are fused (forced together), while those heavier than iron do so through nuclear fission (or “splitting”).

Lithium is an exception. Its nucleus teeters on the brink of instability, physicists note, and can thus be easily jarred apart—releasing a small amount of energy in the process.

Says Wikipedia, “The nucleus of the lithium atom verges on instability, since the two [naturally occurring]…isotopes…have among the lowest binding energies per nucleon of all stable nuclides”.

After the historic experiment of 1932, the focus of fission research quickly shifted to uranium: Which yielded 41 times more energy than lithium, when scientists cracked its nucleus six years later.

Yet lithium was hardly counted out. It remained—and continues to be—an important nuclear undercard, playing crucial roles, both in fission reactor function and nascent fusion energy systems.

Hence the World Nuclear Association reports that lithium “has two important uses in nuclear power today and tomorrow”.

One of these, it avers, is in the cooling systems of pressurized water reactors, where lithium-7, in particular, reduces corrosion and helps control the chemistry.

L-7 is also expected to become a “key component” in the cooling apparatus of molten salt nuclear reactors, when they are more widely deployed at electrical power stations.

The role of lithium, in the emerging nuclear fusion industry, is projected to be even more critical. In this case though, the spotlight focuses more on lithium-6 (7.5 % of natural lithium).

Experts generally agree, that the most feasible method of generating power with thermonuclear reactors, would be to fuse deuterium and tritium—both isotopes of hydrogen.

The ITER newsletter states categorically, that “Once the fusion reaction is established…, deuterium and lithium are the external fuels required to sustain it”.

But Hyperphysics raises a pertinent issue: “Since the most practical nuclear fusion reaction for power generation seems to be the deuterium-tritium reaction, the sources of these fuels are important”.

As for the deuterium part of the fuel, it advises, there is no problem “because about 1 part in 5000 of the hydrogen in seawater is deuterium”.

Seen as a potential source fuel for fusion reactors, a gallon (3.785 liters) of seawater could be used to generate as much electricity as 300 gallons (1,335.5 liters) of petrol.

Likewise, the European Joint Undertaking for ITER, surmises: “The lithium in one laptop battery…with half a [bathtub] of water, would produce the same amount of electricity as… 40 tonnes of coal”.

More problematic, though, is the tritium component of the fuel load. Tritium being radioactive, with a half-life of 12 years, there are no natural sources. It vanished from Earth, exceedingly fast.

Yet this vital ingredient can be manufactured. “Natural reserves of tritium do not exist on Earth,” the Newsletter of the European Joint Undertaking reports, “but it can be made easily from lithium.

“In fact,” it continues, “tritium can be made using the…neutron released from the fusion reaction and offers the possibility of making [it] in situ… The neutron is absorbed by the lithium to produce tritium”.

More recently, the Princeton Plasma Physics Laboratory (PPPL), in the U.S.A. reported that Lithium may help the plasmas fueling fusion reactions to retain heat for longer periods of time.

PPPL found as well, that coating the inner surface of fusion reactor cores with liquid lithium was “a much more attractive alternative to solid metals walls”.

These are but a few of the main factors underlying lithium’s strategic importance—and why Nigerian policy makers should be less pre-occupied with its “commercial exploitation”.

To be continued.

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