%MurNBshimwidths090551; ]> Memorandum from Raymond L. Murray and A. C. Menius to Dr. Clifford K. Beck Machine readable transcription Murray, Raymond L. Menius, A. C. Creation of machine-readable version: Russell S. Koonts Creation of digital images: Russell S. Koonts Conversion to TEI.2-conformant markup: Russell S. Koonts ca. 9 kilobytes NCSU Libraries Raleigh, NC Modern English, MurNBshimwidths090551

Available from: NC State University Archives

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URL: http://www.lib.ncsu.edu/archives/etext/engineering/reactor/murray/

 23 October, 2000

Nuclear Reactor Digitization Project

Raymond L. Murray Reactor Project Notebook

 Illustrations have been included from the print version. Scanned by Russell Koonts with Photoshop 5.0 software. Memorandum from Raymond L. Murray and A. C. Menius to Dr. Clifford K. Beck Raymond L. Murray A. C. Menius

1 p. Manuscript copy consulted UA 105.16

Prepared for the North Carolina State University Science and Technology Electronic Text Center

The lineation of the manuscript has been maintained and all end-of-line hyphens have been preserved.

Keywords in the header are a local Science and Technology Electronic Text Center scheme to aid in establishing analytical groupings.

Library of Congress Subject Headings September 5, 1951 English LCSH manuscript 24-bit color: 400 dpi Memorandum from Raymond L. Murray and A. C. Menius to Dr. Clifford K. Beck Typescript 1 p. September 5, 1951 MurNBshimwidths090551

NCSC-34 September 5, 1951 TO: Clifford K. Beck FROM: Raymond L. Murray and A. C. Menius SUBJECT: Shim Widths CC: A. W. Waltner, Newton Underwood, Leon H. Robinson

The latest Los Alamos cadmium shims are 3" wide, 18" long, and 1/32" thick, and each of the two is worth 13.5 grams. It is clear from the sketches of the side views of two reactors
that on the average the cadmium is much farther from the surface in their case. It is proposed that 4" strip area 40 in.2 be used here, which will correspond to about 25 grams of U-235, giving a total of 50 grams for the two.

Some rough justification is given below: It has been quoted by Las Alamos that the removal of a 4 x 4 graphite block has a value of 5 grams or 5/16 grams/in2, or for our plate 40(5/16) = 12.5 grams.

Since thermal neutrons escaping into the void can still return to the reactor with a block removed, but cannot escape with a cadmium patch, the cadmium would be at least twice as effective.