February, 1952

1. Called E. P. Blizard of ORNL, who is probably the best authority on shielding.
The relaxation lengths quoted in ORNL which I have noted are for fast
neutrons, and represent the reduction in intensity as measured by thermal
neutron counters. Barytes is probably the best bet for our use, with a [lambda]
of 8. A report by Lansing, Thornton and Lane on MTR shielding will be out
soon, and is most appropriate for our study, according to Blizard. There is
to be a meeting with some Canadian people on the week of Feb. 26, in which
ORNL will describe the whole picture of shielding, particularly of the
inexpensive variety for permanent reactors. He highly recommends that we
attend this, and will call or telegraph the exact date(s) of the meeting.

2. Discussed several items with A. D. Callihan.

• (a) Reactor building design. He objected to the cut-up center rooms,
  suggesting one large room with partitions if desired. Provisions
  for women’s dressing rooms are needed. Also, the dressing rooms
  should be off the traffic line, because of the visitors that are
  sure to come around to see the labs. He liked the sizes of the rooms.
• (b) Water window. Callihan thinks it should be made in panels of reasonable
  size, and of stainless steal to avoid rust. Urges solid live rubber
  gaskets rather than caulking, addition of a salt in the water to inhibit
  organic growths. Their windows are truncated pyramids 5' 6" square on the
  front (near reactor), 3 1/2' x 2 1/2' on bask. Glass thickness 1 1/4"
  front, 5/8" back of "Herculite" a tempered glass put out by Pittsburgh
  Plate Glass Co.
• (c) Cd vs. B shielding at the end of the thermal column. He agreed B would
  be preferable.