Answer: 400 kilograms--about 880 pounds. Considering the great size and high speed of the boat, and the long duration of their voyages, this is a remarkably small weight of fuel.

Source: I know you'd like to think the source is some secret document, but it is from our friend's 14-year old daughter's science textbook (I was looking over her homework). Judging by the accompanying photo, I believe this applies to the Los Angeles-class attack submarines, not the larger nuclear-missile armed Ohio-class submarines ("boomers").

Thanks to astute readers Jeff O. and Steve T. for correcting my gross error posted earlier.

According to The Nuclear Fuel Cycle:

For a reactor with an output of 1000 megawatts (MWe), the core would contain about 75 tonnes of low-enriched uranium. To maintain efficient reactor performance, about one-third of the spent fuel is removed every year or 18 months, to be replaced with fresh fuel.

Total cost is thus about US$ 1393 for 1 kg enriched fuel, plus about $240 for actual fuel fabrication. This will yield about 3900 GJ thermal energy at modern burn-up rates, or about 360,000 kWh of electricity (at 33% thermal efficiency), and does the same job as about 160 tonnes of steaming coal for a total cost of 0.45 cents/kWh (US$) - a bit more at lower burn-up.

Out of the estimated 468 naval reactors that have been installed on 258 submarines and service ships, 24 use fuel enriched to 90% U-235. Most of the reactors were fueled with U-235 enriched to 21-45%. A typical reactor core contains 315 kg of uranium.

Thank you, Scott H. ($30), for your generous second contribution to this humble site. I am greatly honored by your support and readership. All contributors are listed below in acknowledgement of my gratitude.


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