NEVADA TEST SITE
The Rainier underground shot now is scheduled to be ready for firing at 10 a.m. PDT, Thursday, September 19, in a chamber at the end of a 2,000 foot tunnel dug horizontally under a tufa rock mesa at the northern edge of Yucca Basin.
The shot will be controlled primarily from a special forward Control Point installed in an existing timing station about 10 miles from the tunnel mouth, with 22 experiments connected to the sequence timer. There will be additionally be a forward control area about two and one-half miles south of the tunnel mesa. There will be no associated military or civil effects, and no participation by aircraft at shot time.
The following summarizes information on the primary purpose of the test, on its conduct, and on scientific experiments associated with it which have been released in various statements and meetings with the press beginning last spring.
The idea for placement of experimental nuclear devices deep underground grew out of the thinking of weapons scientists as to means for avoiding the release of radioactive contamination into the air. The specific method now being tested grew out of suggestions by Dr. Edward Teller at the University of California Radiation Laboratory and Dr. David Griggs of the University of California at Los Angeles. The project was planned, justified and is being conducted by the Livermore Branch of UCRL.
Before the project was scheduled it was considered that there should be studies as to the possibilities of seismeic disturbances. A considerable volume of data obtained by the U.S. Geological Survey was analyzed by an advisory group of seismologists and geophysicists including that obtained from firing underground high explosive charges at Nevada Test Site last spring. The advisory group advised the test organization and the AEC that the detonation would have no adverse seismic effects.
The primary purposes of the shot are to verify that limited nuclear devices can be fired underground without the escape of radioactive materials into the air and to determine if instrumentation methods can be developed so scientists could know exactly what happened during the detonation.
Subsequently, seismologists and geophysicists became interested in making use of the detonation for an earth-study experiment in connection with the international geophysical year. Given data on explosive force time of detonation and sufficiently exact positioning, the detonation would provide a means for study of the transmission of seismic waves and the structure of the earth. This associated use was approved and seismologists and geophysicists throughout the world will conduct studies.
The nuclear device to be used will release between one and three kilotons of explosive energy. This is far below the energy released by majority of devices fired at NTS since 1951. Every nuclear detonation at NTS has resulted in energy being transmitted to the surface of the earth and through the earth whether the shot was fired in the air, on a tower, or on the surface.
Other underground shots were fired in the fall of 1951 and the spring of 1955 primarily for effects studies and were of limited yield because of the fallout hazard created. Safety experiments fired in the current series have been placed in tunnels and in deep shafts.
Energy transmitted through the earth by all such shots has been studied. Based on studies of such energy transmission from above surface shots in the present series, the seismic waves resulting from 10 to 150 miles from NTS have been: Body waves from 0.10 seconds to 0.04 seconds with periods of 0.02 seconds predominating; and surface waves of 0.3 to 1 second and greater. Periods produced by the Rainier tests are expected to be comparable. There has been no record even close to NTS of any significant earth shock from any test in Nevada and it is not anticipated that the Rainier seismic wave will be greater than that from previous tests.
The tunnel, dug horizontally through the tufa under a mesa, makes three right hand turns, and extends about 2000 feet. The detonation chamber is 800 feet from the side of the mesa and 900 feet under the mesa top. It is so located as to close the tunnel through blast effects before any energy manifestations can escape through the tunnel.
It is anticipated that the force will be largely-absorbed within the immediately adjacent tufa rock, that there will be no escape of radioactive material, and that the only visible physical manifestation may be a slight heaving of the mesa top surface. Dust may result from the surface heaving. The weathered rock along the mesa side may be disturbed. It is possible that some steam may escape to the surface through fissures.
The exact location of the chamber is:
Latitude 37 degrees 11.7 minuted; longitude 116 degrees 12.2 minutes; and altitude 6611.43 feet (mean sea level).
Detonation time will be 10 a.m. PDT plus or minus two minutes. If there is any postponement or any delay longer than 2 minutes the firing will be postponed a full 24 hours.