|
It became clear to Groves
that he would have to find a way for a combination of isotope
separation processes to produce enough fissionable material for
bombs. This meant making changes in the racetracks so that they
could process the slightly enriched material that was being produced
at K-25. He then concentrated on further expansion of the
electromagnetic facilities. Lawrence, seconded by Oppenheimer,
believed that four more racetracks should be built to accompany the
nine already finished or under construction. Groves agreed with
this approach, though he was not sure that the additional racetracks
could be built in time to make a difference.
As the K-25 stock continued
to drop and plutonium prospects remained uncertain, Lawrence lobbied
yet again for further expansion of Y-12, arguing that it provided the
only possible avenue to a bomb by 1945. His plan was to convert
all tanks to multiple beams and to build, yet again, two more
racetracks. By this time even the British had given up on
gaseous diffusion and urged acceptance of Lawrence's plan.
Time was quickly running
out, and an element of desperation crept into decisions made at a
meeting on July 4, 1944. Groves met with the Oak Ridge
contractors to consider proposals Lawrence had prepared after
assessing once again the resources and abilities of the Berkeley
Radiation Laboratory. There was to be no change in the completed
racetracks; there simply was not enough time. Some improvements
were to be made in the racetracks then under construction. In
the most important decision made at the meeting, Lawrence was to throw
all he had into a completely new type of "calutron" that
would use a thirty-beam source. Technical support would come
from both Westinghouse and General Electric, which would cease work on
four-beam development. It was a gamble in a high-stakes game,
but sticking with the Alpha and Beta racetracks might have been an
even greater gamble.
See:
'Enrichment of
Uranium"
|