Test facilities at the NTS's Nuclear Research and Development Area consist of three reactor test cells, an engine test stand, two large assembly-disassembly facilities and two remote control facilities that were reassigned to other purposes, it says.

"Furthermore, these facilities no longer comply with current environmental and nuclear safety standards and regulations regarding nuclear propulsion system testing for the reactor concept levels envisioned," the report adds.

Design and operation of the Ground Test Facility is expected to require a major engineering project "to provide a system capable of removing fission products from the engine exhaust. . . .

"The facility had to be capable of handling both normal operating conditions, as well as off-normal conditions that might arise from a catastrophic engine failure."

The report promotes the Savannah River Site as a place to develop fuel for the nuclear rocket. Using it to produce the nuclear fuel "and act as the lead laboratory for excess HEU (highly enriched uranium) deposition . . . will minimize logistic and nuclear proliferation concerns," the report says.

Tunnels at the Nevada Test Site, built for nuclear bomb testing, were considered as a possible location. "Although location of the Ground Test Facility underground might provide an additional margin of safety, there are still a number of questions concerning the use of existing tunnels or new tunnels" at the test site for this purpose, the report says.

Drawbacks cited to using the NTS tunnels include:

• The tunnels may be needed in the future as sites for underground nuclear shots.

• They are far enough away from existing nuclear rocket test facilities at the NTS to complicate the logistics of their use.

• "Given the large volumes of gas that would be released during engine tests, the existing volumes of these tunnels does not appear to be adequate to contain exhaust gases at acceptable pressures." That problem would be magnified if abnormal situations developed during testing.

• "During normal operations, the tunnels would be contaminated by fission products."

Another option considered was cleaning up the exhaust gases and then releasing them to the atmosphere "as was done in the Nuclear Furnace program in the 1960s."

Cleansing the exhaust gases could involve spraying them with water to cool them, and use of filters, dryers and hydrogen cooling to condensing water vapor. "Charcoal beds would be used" to remove xenon and krypton gases from the exhaust "which was then flared to the atmosphere."

Contacted by telephone, Williams said the study was preceded by an evaluation by NASA in 1993. The earlier study "included the Nevada Test Site as well as Savannah River Site and a number of other sites."