anew Military Application The re-entry team, on Monday, March 16, 1964, observed a crack in the solid ground approximately 30 feet northnortheast of the rim of the crater (130 feet from ground — zero) and estimated this crack to be approximately eight or ten feet in length (at the surface) with a gas eroded, highly radioactive hole approximately four inches in diameter near the north end of the crack. The conclusions reached after an extensive investigation were as follows: a. The most probable cause of the venting was an apparent local weakness of the alluvium which cracked under the ground shock from PIKE and thus permitted the escape of the debris. b. c. As of March 22, 1964, (nine days after the detonation) ‘there was no evidence that a health hazard had been created, On the basis of current evidence, none‘is expected to develop. DOE ARCHIVES The elaborate network of stations supported by airborne sampling equipment, all designed to completely document inadvertent ventings, has to date functioned as planned. There is no positive evidence that debris crossed the border in measurable and identifiable amounts. If trace amounts did cross the border, they were not measurable by normal aerial surveys since measured radiation levels in Ariz. were almost at background values, as determined by the extremely sensitive instruments in the AEC monitering aircraft. TEST PLANNING Underground Test Series ~- NIBLICK - NTS NIBLICK IV(April - June 1964) A tentative schedule of events for April is as follows: <9 nr-s7 9

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