%MurNBfurther091050; ]> Further Notes on Characteristics of N. C. State Research Reactor [a machine-readable transcription] Beck, Clifford Menius, Arthur Murray, Raymond Creation of machine-readable version: Russell S. Koonts Creation of digital images: Russell S. Koonts Conversion to TEI.2-conformant markup: NCSU Science and Technology Electronic Text Center. ca. 12 kilobytes NCSU Libraries. Raleigh, NC. Modern English, MurNBfurther091050

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 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. Further Notes on Characteristics of N. C. State Research Reactor <author>Clifford Beck</author> <author>Arthur Menius</author> <author>Raymond Murray</author> <respStmt> <resp/> <name/> </respStmt> </titleStmt> <editionStmt> <p></p> </editionStmt> <extent>2 pp.</extent> <publicationStmt> <publisher></publisher> <pubPlace></pubPlace> <date></date> <idno>Manuscript copy consulted: NCSU Libraries call number UA105.16</idno> </publicationStmt> <seriesStmt> <p/> </seriesStmt> <notesStmt> <note></note> </notesStmt> </biblFull> </sourceDesc> </fileDesc> <encodingDesc> <projectDesc> <p>Prepared for the NCSU Libraries Science and Technology Electronic Text Project.</p> </projectDesc> <editorialDecl> <p>Spell-check and verification made against printed text using Notetab spell checker.</p> <p>The lineation of the manuscript has been maintained and all end-of-line hyphens have been preserved.</p> <p>The images exist as archived TIFF images, one or more JPEG versions for general use, and thumbnails.</p> <p id="ETC">Keywords in the header are a local Electronic Text Center scheme to aid in establishing analytical groupings.</p> </editorialDecl> <refsDecl> <p>ID elements are given for each page element and are composed of the text's unique cryptogram and the given page number, as in NEprop033050a for the title page of Clifford Beck's Proposal.</p> </refsDecl> <classDecl> <taxonomy id="LCSH"> <bibl> <title>Library of Congress Subject Headings 1950, September 10 English non-fiction; prose LCSH 24-bit color; 400 dpi Further Notes on Characteristics of N. C. State Research Reactor Typescript 6 pp. Sep. 10, 1950 MurNBfurther091050

Reac. Memos Notebook

<hi rend="underline">FURTHER NOTES ON CHARACTERISTICS OF N. C. STATE RESEARCH REACTOR </hi>

September 10, 1950

Clifford Beck Arthur Menius Raymond Murray

DEPOSITION OF LONG-LIVED FISSION PRODUCTS FROM THE REACTOR

At upper limit may be calculated for the quantity of long-lived fission prod- ucts which could collect on the walls of buildings surrounding the reactor.

1. The prevailing wind - i.e. 14% of the time - is from the southwest.   2. The only long-lived gaseous fission products which will escape from the reactor are Kr85, Rb87, Cs137.   3. Assume that the reactor operates steadily (24 hrs/day) at 10 KW level for ten years The activity of the 3 listed elements at the end of ten years due to the cumulative total of each element produced is:

Element Boiling Point Half Life Fission Yield (f) Disintegrations/second from TotalAmt. Produced in 10 years (= 1.4 x10-3) (3x1010) P(watts) f(1-e -.693t/λ) Kr85 gas 10 y 0.24% 3.9 x 108 Rb87 700° 6.3x1010y 3. % Negativeligible Csl37 670° 33 y 6. % 2. x 1010

4. Assume that all of the Kr85 and 10% of the Cs137 (because of boiling point and low reactor temperature) escapes into the atmosphere. Rb87 may he neglected in comparison with Cs137 because of its long half-life.   5. Assume that a building 60 feet high is 200 feet northeast of the reactor, directly in the path of the prevailing wind. No building will be closer than this, and none would be exposed to the stack exhaust more than this 14% of the time.   6. Assume that the stack gases are released at sufficiently low level (30 or 40 feet) that the expanding cone-of-exposure at the building in question is at maximum; i.e. the area exposed to the cone of stack gases is 1/7 (200') 28' in diameter, = 5 x 105 cm2 area.   7. Assume that 0.05% of the radioactive gases in the cone of gases from the stack actually deposits on the building walls and is not subsequently weathered off.

The activity on the building wall at the end of ten years is then Kr85: 3.9 x 108 x 0.05%= .2 x 106 disintegrations/sec. Cs137: 2 x 1010 x 10% x 0.05% = 1 x 106 Total= 1.2 x 106 disintegrations/sec/5 x 105 cm2 = 1.2 x 106 = 2.4 disintegrations/sec/cm2 5 x 105

HEATING OF REACTOR AFTER SHUT-DOWN

If the reactor is "shut-down" and the cooling water is cut off simultaneously, there is the possibility of a rise in temperature due to the activity of the fission products. The power due to the activity of β and γ rays from the fission products is given by (Way and Wigner)

where f is the previous rate of use of uranium, T is the previous operation time of the reactor and t is the time after shut-down. At 10 KW f ≃ 1/100 gms/day. Assume that T = 100 days and t = 0.001 (about 1 1/2 minutes). Then

E (T,t) = 225 watts.

Calculations on the conduction of heat through the graphite, assuming reactor temperature, Tr 80°C and temperature at end of graphite reflector, Tt 20°C, indi- cate that about 1 KW can be thus dissipated.

The reactor temperature, therefore, will decrease after shut-down, whether the cooling water continues to flow or not.

RADIATION EXPOSURE HAZARD RESULTING FROM EXPLOSIVE VAPORIZATION OF 50% OF FISSION PRODUCTS IN THE REACTOR

If, due to sabotage, a non nuclear explosion should vaporize 50% of the fission products accumulated in the reactor, an approximation may he made of the radiation exposure hazard which could result.

The hazard is calculated for two possible cases: 1. The explosion causes formation of a small cloud near ground level, which subsequently drifts away. The cloud in assumed to spread laterally 1/7th the distance of downwind travel. 2. The explosion causes formation in the reactor room of a cloud which is exhausted through the building stack (150 feet high). The cloud subsequently drifts away from the top of the stack, spreading as above.

Assumptions:

1. Reactor has operated steadily at 5 KW. 2. Wind velocity is 2 m/hr. 3. Range of β = 5ft; of γ = 1000 ft. 4. Exposure (Roentgens) = 2 x 1010

Case 1. Cloud is formed near ground-level and drifts toward a man 200 feet away. The man's exposure is

Case 2. Cloud is dispersed from top of 150 foot stack and reaches ground level at 1050 feet. A man's exposure at 1050 feet, at the point the cloud reaches ground level, is

TOLERANCE LEVELS

The daily tolerance level of permissable total body exposure to radiation is 0.1 r/8 hours. Each or the following fluxes will result in approximately 0.1 r/8 hrs:

802 Mevβ's/cm2 sec.2702 Mevn's/cm2 sec.33002 Mevγ's/cm2 sec.46,5001/40 evn's/cm2 sec.

Plutonium tolerance - 5 x 10-5 μ grams/cc in drinking water

Drinking water tolerance 10-6 curries/cu ft.

|←40"→|←6'→|

270 n/cm2/sec 0.1r in 8 hrs. 2x1018 n/sec

Father Joseph Lynch, Fordham Earthquakes