Trinity Remembered

Procedure for Final Assembly

- K. T. Bainbridge

The procedure used for the final assembly of the bomb is probably best given by the memorandum from N. E. Bradbury, which gives the procedure to be followed, as discussed by all members concerned, and that was evolved from the dry run.


by N. E. Bradbury

Saturday, 7, July, 1700

Schaffer Shake Test ready to deliver.

Sunday, 8, July, 0830

Assemble Shaffer Shake Test, load on truck.

Monday, 9, July, 0830

Schaffer Shake Test charge cap and dummy plug and inspect top of charge only after 3-h riding.

Tuesday, 10, July, 0830

Completely disassemble charge and inspect each casting for condition. Verbal report of charge condition by 1630 Tuesday. Reassemble and remove.

Wednesday, 11, July, 1730

Both charges completely papered. Work another night shift if necessary to complete this job. Request personnel as necessary. This job must be done so that assembly of both charges can start on Thursday, 12 July, at 0830.

Thursday, 12, July, 0830

Use two groups-one at V-Site to assemble TR charge (Lt. Schaffer supervises), and one at Pajarito for Creutz charge (North supervises). Tamper needed by 1000 at V-Site.

Thursday, 12, July, 1500

Assembly of TR charge complete. Notify interested personnel that it is ready for inspection if desired.

Thursday, 12, July, 1600

Seal up all holes in case; wrap with Scotch wrap (time not available for strippable plastic). Start loading on truck. Tie down to truck body.

Thursday, 12, July, 1600

Box charges, inner and outer, with two spares for each. Stow on truck so they cannot shift and are padded from truck bottom.

Friday, 13, July, 0001

TR charge starts on its way to TR. G-2 escort cars fore and aft. G. B. Kistiakowsky to ride in fore car.

Friday, 13, July, 1200

TR charge arrives at base of tower. Following personnel to be at base of tower by 1300.
N. E. Bradbury
G. B. Kistiakowsky
R. S. Warner
H. Linschitz
Lt. W. F. Schaffer
T13 Jercinovic
T13 Van Vessem
A. B. Machen

Friday, 13, July, 1300

Assembly starts.

Unloading at TR

  1. Truck backs up to base of tower.
  2. Tarpaulin is removed, cradle and assembly unlashed.
  3. Main hoist lifts sphere off cradle with spreader bar or tongs.
  4. Drive truck out from under sphere.
  5. Place new cradle under hoist and lower sphere suspended by tongs into it with main hoist.

Assembly at TR

  1. Sphere is now resting on cradle with polar cap up.
  2. Detach main hoist; pick up gently with hook, lower, pull out over gadget and secure.
  3. With jib hoist, remove polar cap and dummy plug. Special polar cap and funnel put in place. Gadget now belongs to tamper people (at about 1400 on Friday). Before their taking over, a 15-min period will be available for generally interested personnel to inspect the situation. After this time, only G-engineers and two representatives from the assembly team will be present in the tent.
  4. G-engineers work till 1600 with active material insertion.
  5. Light must be available to work in tent at night.
  6. At 1600 dummy plug hole is covered with a clean cloth and explosives people take over. Attach tongs to tent peak by chain. Place tongs on trunnion. Lift sphere and turn over with jib hoist for HE insertion. Return sphere to cradle.
  7. Place hypodermic needle in right pluce. (Note: Check this carefully.)
  8. At this point another 15-min period will be available for inspection by generally interested personnel.
  9. Insert HE-this is to be done as slowly as the G-engineers wish. Have on hand extra paper, if charges are slightly small, grease, and hypodermic needle grease gun. Be sure glass tape and/or shim stock shoe horn is on hand.
  10. When HE has been inserted and explosives people and G-engineers are satisfied that all is OK, another inspection period of 15 min will be available.
  11. Lift sphere with tongs by chain to tent peak. Return to polar cap up position. Remove special polar cap with jib hoist; replace with regular polar cap.
  12. Turn sphere over with tongs, chain and tent peak so that lug is up.
  13. Place sphere in special cradle for tower top, and attach cradle firmly to sphere. Remove all tongs, chains, etc., and generally clear deck.
  14. Leave tent in place till morning.
    NOTE: The HE vacuum cup has arrived and appears to be extremely useful in handling HE charges. It is possible that the entire assembly may be done in the vertical position using the jib hoist and vacuum cup to lower the HE as slowly as the G-engineers wish. This would then require no handling between tent peak and tongs, and the sphere will be left overnight with the cap up and in a small dishpan.
  15. It is anticipated that we will leave the tent (guarded) at about 2200.

Saturday, 14, July, 0800 Lift to tower top

  1. Remove tent with main hoist.
  2. Turn over with main hoist and place on special cradle. (This operation necessary only if not previously done as it would not be in a vertical assembly.)
  3. Rig guide lines.
  4. Lift to tower top. Ready for X-unit at 0900.
  5. Bring up G-engineer footstool.

Saturday, 14, July 0900, Operations aloft

  1. Wiring of X-unit proceeds under the direction of and by explosives people. Note that X-unit should have cables attached to cone before this time.
  2. Detonators are staked to coax by Caleca of detonator group.
  3. Detonators are placed by Caleca to conform with requirements of informer switches. HE people stand by to criticize potential rough handling.
  4. Detonators and informers in place, verified by Greisen.
  5. X-unit and informer unit safed, verified by Bradbury or Kistiakowsky.
  6. X-7 will provide all detonators, informer switches, informer cables (adequate length), informer apparatus. (Where they get it is their business.) X-5 will supply prepared detonator cables. X-6 will obtain detonator springs and other necessary gear from appropriate sources. X-6 will supply all fittings for wiring. Schaffer to check that all mechanical parts (nuts, bolts, etc. ) are supplied.
  7. Note that once detonators are on sphere, no live electrical connection can be brought to x - unit, informer unit, or anywhere else on sphere. Hence all testing must be done before sphere is lifted to tower. After that it is too late.

Saturday, 14 July, 1700

Gadget complete

Sunday, 15 July, all day

Look for rabbit's feet and four-leaved clovers. Should we have the Chaplain down there? Period for inspection available from 0900-1000.

Monday, 16 July, 0400


Source: K. T. Bainbridge, Trinity, Los Alamos Scientific Laboratory, May 1976, LA-6300-H, National Technical Information Service