dasa.from Eniwetok are being forwarded to Sandia Corporation for evaluation. ject 34.5 was responsible for supplying Zippers, an external initiation device, to the LASL and UCRL weapon assembly groups. The Zippers were operated successfully on 27 nuclear shots and one safety test. A new Zipper, S 102, was used for the first time on Operation Hard- tack. It proved to be a reliable and versatile unit weil suited for fleld use. Specifie details and operating characteristics for the S 102 Zipper can be obtained by referring to the Sandia Corporation Publication, "Operating Man- ual for the S 102," 1411-186. Trailers at Eniwetok and Bikini that contained test equipment were used to prepare the Zippers prior to installation at the zero site. interval generator with an accuracy of 5 musec was used as atime standard . A silver counter was used to measure total neutron output. Oscilloscope pictures were taken of the output of a scintillator-photomultiplier tube in order to provide neutron pulse shapes for evaluation. At the zero site the Zippers were installed in mounts provided by the weapon assembly group. After installation the Zippers were checked on dry runs, at which time the neutron output was monitored by portable scintillators and by Project 34.1 using high time resolution telemetry. Individual Zipper books containing specific information on each shot have been completed. These books will be available for reference at Sandia Corporation, 5231. : Project 34.6 had responsibilities in three distinct and unrelated areas as follows: (1) systematics, which consisted generally of an intimate and current knowledge of the complete device firing systems, with staff advisory responsibilities to the Commander, Task Unit 2; (2) procurement, test, and . field support for X-unit cables for all UCRL events; and (3) detonator elec- trical test prior to, during, and after assembly of the complete device. The systematics function was a "first time" venture and was conceived by CTU-2. Sandia furnished this support at the request of UCRL. This — function was particularly valuable in the preoperational period and was chiefly one of coordination between various "interconnected" agencies during the Planning phase. In the operational period this function, although still valua- ble, suffered somewhat from manpower shortages, inasmuch as the other two functions are absolutely necessary to a shot and systematics is not. For future operations it seems that the Arming and Firing Coordinator would be in a better position to handle the function with a minimum of dupli- cation of effort. It was valuable, however, for the systematics coordinator to be located physically near UCRL in order to better handle the valuable preoperational phases. The detonator test function is self-explanatory. Electrical tests were made on loose detonators or detonator cable assemblies at the request of any of the device field teams, and generally at four steps in the history of the device as follows: (1) prior to device assembly, (2) after device assembly and prior to transfer to zero site, (3) after transporting to zero site, and (4) at pre-arm. The X-units used on this operation were MC-530 or MC-462 war-re- serve quality. The stock units were slightly modified, tested by SCLB and UCRL for simultaneity, and then forwarded to EPG for use. All X-units performed as expected; there were no failures. On one particular shot, Juniper, Project 34.6 designed, built, tested, and flelded a hydrogen-thyratron-