%MurNBcoolingwater011652; ]> Memorandum from R. L. Murray to C. K. Beck Machine readable transcription Murray, R. L. 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, MurNBcoolingwater011652

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 25 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 R. L. Murray to C. K. Beck R. L. Murray

2 pp. 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 January 16, 1952 English LCSH manuscript 24-bit color: 400 dpi Memorandum from R. L. Murray to C. K. Beck Typescript 2 pp. January 16, 1952 MurNBcoolingwater011652

January 16, 1952 TO: C. K. Beck FROM: R. L. Murray SUBJECT: ACTIVITY OF REACTOR COOLING WATER CC: Reactor Committee

In preparation for an earlier report, Dr. A. C. Menius computed the induced activity in reactor cooling water exposed for two seconds in a thermal flux of 1012. These calculations are brought up to date in light of the final decision on flow rates and cooling coil dimensions, and an independent check provided.

Analysis: A given cubic centimeter of water remains within the core flux for a time given by t = l/v/A where l the path length (7 feet), v is the flow velocity corresponding to 1 gallon/minute in each of four tubes, and A is the internal cross-section of the pipe (1/4" I.D.).

Thus,

The rate of formation of radioactive atoms is given by g = φNσat where φ is the average thermal flux (5 x 1011), N is the number of target atoms per unit volume, and σa is the thermal neutron cross-section, N = (ppm)(10-6)(0.0335 x 1024)(isotopic abundance).

The activity induced in (d/sec) is λg or .693g/tH where λ is the decay constant in sec-l and tH is the half-life in sec.

In the attached table, a conservative assumption of exposure time of 2 seconds in a flux of 1012 is still used, ie, φt 2 x 1012 cm-2.

TargetIsotopeFromthe im-purityPars perMillionof WaterActiveiso-topeHalf-lifeλ(sec-1)σa ofTarget(barns)Abundanceof TargetIsotope(%)N(cm-3)Activity(d/sec)Si30SiO29.8S312.7h.7.1x10-50.123.11.0x1016.017 .17?Fe54Fe0.02Fe553y7.3x10-925.93.95x1013negFe58Fe0.02Fe5947d.1.7x10-70.360.342.3x1012negCa44Ca8.7Ca45152d.5.3x10-80.62.16.1x1015negMg26Mg1.4Mg279.58m1.2x10-30.0511.35.3x10150.64Na23Na+K4.2Na2414.9h1.3x10-50.61001.4x10172.2C13CO3HCO33.914C145,720y3.9x10-12≃0.11.16.6x1014negS34SO411S3887d.9.2x10-80.264.181.5x1016negS36SO411S375m.2.3x10-30.140.01365.0x10130.032Cl35Cl4.9Cl36S352x105y87d.1.1x10-139.2x10-8420.3475.475.41.2x10171.2x1017neg10-2Cl37Cl4.9Cl3838.5m3.0x10-40.624.64.0x101614F19F0.1F2012S.5.8x10-20.0091003.35x10153.5N15NO30.1N1635S.2.0x10-20.0000130.3651.2x1013negO18WaterItself106O1929.4S.2.4x10-20.00020.2046.8x1019653

The O19 activity of 653/3.7x104 = 0.018 μc/ml is thus dominant initially.

Since its half-life is half a minute, there will be no danger by the time the discharged water reaches points of possible exposure.

The Cl38 activity corresponds to 3.8x10-4 μc/ml which is of the order of maximum permissible concentration for drinking water.

Since all other elements lie below these, the overall danger is believed to be negligible.

Program Administration and Installation Design of the Nuclear Reactor Project at N. C. State College, C. K. Beck, et al.

Supplied by Mr. John Andrews, Raleigh Public Utilities Dept. Letter of July 27, 1950 to A. C. Menius. (ppm = number of atoms per molecule of H2O; 0.0335 x 10+24 H2O per cm3)

Nuclear Data, U. S. Dept. of Commerce, National Bureau of Standards, Sept. 1, 1950

Reaction Cl35(n,p)S35.

Assuming σcl = 32 is principally due to its lighter isotope.