house at the top of the tower. The tubes started from the roof of Station 131 as four pipes, converging into two pipes at the 1374 foot level, and finally into a single pipe at the 150 foot level. The tubes were shielded with lead at different tower levels. The sketches showing the weights involved were furnished H & N by the User at a meeting held at Los Alamos on June 23, 1950. To speed procurement, UCRL furnished the tubes, the lead shielding, and platforms to support the lead; however, H & N had to adapt the tower to these loads and also install this equipment under the direction of UCRL. After the tower was fabricated and shipped, the User requested that the weight of the lead at the first level above the base be increased considerably above that first stipulated. Since the tower framing was not capable of taking this increased loading, H & N prepared designs and supplied material for a platform for the lead, supported from the roof of Station 131 by steel pipe columns. Since the 200 foot tower or towers were to be used in lieu of 300 foot towers, no additional hoisting equipment was required. Main hoist equipment, skip hoist equipment, and the portable hand winches, however, had to be modified to conform to the new requirements, The changes involved were due to: 1. The load required for the 200 foot tower main hoist was 15,000 pounds instead of 10,000 pounds as used on the 300 foot tower (Drawing 3G-5422). 2. The skip hoist was operated outside at the 200 foot tower instead of inside as on the 300 foot tower and did not have to open a trap door as it approached the top level (Drawing 3G~5423). 3, The hand winch used in the tower cab for pulling coaxial cables, mountings, and cable guides had to be redesigned due to difference in structural conditions in the tower eab (Drawing 5430.1). In order that the 300 foot tower main hoist machine might be used for the 200 foot tower and its 15,000 pound load, it was decided to raise the load at 20 fpm maximum on a three-part cable. This required the relocation of one sheave and the addition of one sheave, mounted on the structural A-frame, but did not change the power requirements. It also required dead-ending the hoisting cable at the load block, in- stead of at the A-frame as was done on the 300 foot tower. This required a minor change in the load block yoke for attaching the cable. A slight change in the location of the limit switch on top of the 4frame was also required as well as a slight change in mounting the limit switch weight. Drawings were prepared showing these changes. Figure 5.11-6 shows the hoist machine used for both 200 foot and 300 foot towers. alhd