American Scientist

To the Editors:

I enjoyed reading Lee Langston’s optimistic column “A Path for Nuclear Power” in the March–April issue, because I have long been a (somewhat discouraged) supporter of nuclear power.

One point jarred me a bit: Langston stated that because helium is inert, the contact with radioactive pebbles, which are used instead of uranium fuel rods in a pebble-bed reactor, did not render the gas (the working fluid and coolant) radioactive.

What is it about chemical inertness that prevents the gas from becoming radioactive? Radon is a gas that is infamous for its radioactive properties.

Byron Rogers
Lunenburg, Nova Scotia

Dr. Langston responds:

Helium (atomic number 2) and radon (atomic number 86) bracket the inert (noble gas) family in the Periodic Table. Radon, one of the densest of gases, is the only gas that has radioactive isotopes under normal conditions. Helium, one of the lightest of gases, is both chemically inert and cannot be transformed into a radioactive element under normal and pebble-bed modular reactor conditions.