This is an article that was pointed by my supervisor from work, George Grodentzik. An article from ZDNET titles, "A Micro Nuclear Reactor in your Garden ?" claims of having a $25 million dollar cost which can power up to 10,000 homes in the U.S. and perhaps up to 60,000 homes in the developing countries. The two basic applications of the "HPG" will be able to produce electricity and provide a supply of clean water.
Definiion : Hyperion's "nuclear in a box" technology are about the size of a typical backyard hot tub, and are able to generate 70 megawatts of heat energy, or 27 megawatts of electricity from a steam turbine – enough to power 20,000 homes. The nuclear battery is sealed and buried at the generation site, and taken back to the factory for refueling every five years. The reactor unit’s size is supposed to bring down capital costs 30% and operating costs 50%

picture taken from
http://www.hyperionpowergeneration.com/HPG's website quotes : Think About It: "Global warming. Dependence on foreign oil. Infrastructure vulnerable to natural and manmade catastrophes. Undrinkable water, poverty, disease, social unrest. Hyperion, nuclear power and the many benefits it offers: clean, emission-free, affordable energy — was only available from large, expensive nuclear power plants that took 10 years or more to build. And, many locations that could have benefited from nuclear power were not appropriate — the land was not available or the population was not large enough to warrant a huge power plan."

picture from
http://www.hyperionpowergeneration.com/Perfect for moderately-sized projects, Hyperion produces only 25 MWe — enough to provide electricity for about 20,000 average American sized homes or its industrial equivalent. Ganged or teamed together, the modules can produce even more consistent energy for larger projects. NOTE : A different source quotes 27 M We
So what is the technical side of all this ? Neither ZDNet's article on HPG's main site explains the technical details of all this. Curious, I ended up doing a little more research. A small wiki article, though I could not find the source sounded about right. It states :
"The design is notable for the use of uranium hydride (UH3) enriched to 5% U-235 as the nuclear fuel, rather than the usual metallic uranium or uranium dioxide that composes the fuel rods of contemporary light water reactors. In fact, within the application, the contemporary "rod" based design with fuel rods and control rods is completely omitted from the proposed reactor design in favor of a "tub" design with passive heat pipes conducting heat to the heat exchanger running through the "tub" of granulated uranium hydride.
According to the aforementioned patent application, the reactor design in question begins producing power when hydrogen gas at a sufficient temperature and pressure is admitted to the core (made up of granulated uranium metal) and reacts with the uranium metal to form uranium hydride. Uranium hydride is both a nuclear fuel and a nuclear moderator; apparently it, like other nuclear moderators, will slow neutrons sufficiently to allow for fission reactions to take place; the uranium-235 atoms within the hydride also serve as the nuclear fuel. Once the nuclear reaction has started, it will continue until it reaches a certain temperature, approximately 800 degrees Celsius, where, due to the chemical properties of uranium hydride, it chemically decomposes and turns into hydrogen gas and uranium metal. The loss of neutron moderation due to the chemical decomposition of the uranium hydride will consequently slow--and eventually halt--the reaction. When temperature returns to an acceptable level, the hydrogen will again combine with the uranium metal, forming uranium hydride, restoring moderation and the nuclear reaction will start again.
This makes the reactor a self-regulating, dynamical system, as with a rise in temperature, nuclear reactivity will substantially decrease, and with a fall in temperature, nuclear reactivity will substantially increase. Thus, this reactor design is self-regulating, meltdown is impossible, and the design is inherently safe.
The only hazards are those of all nuclear materials, namely those of radiation, but this is significantly mitigated by the fact that the reactor design is intended to be buried underground and only dug up for refueling every five years, at which point, assuming proper safeguards are used, exposure to radioactivity is a comparatively trivial concern. Spent fuel is also a concern, but this is mitigated due to certain technologies and advantages that make the design in question's used fuel more suitable for nuclear recycling. In particular, the patent application for the design indicate that using a thorium-based fuel cycle instead of a uranium-based one with this type of reactor will allow far greater recycling potential than presently is found in standard used fuel."
For those who want to do more reading :
http://en.wikipedia.org/wiki/Hyperion_Power_Generation (technical specs)
http://www.hyperionpowergeneration.com (HPG's main website)
http://blogs.zdnet.com/emergingtech/?p=1089 (zdnet's article with interview quotes)