. 655 Pl ORNL UNCLASSIFIED .* C },. . . ; 1 : " ... "-. . . 1 .. . ORNLIGST DISTRIBUTION OF DOSE AND DOSE EQUIVALENT IN A CYLINDRICAL TISSUE PHANTOM FROM FISSION SOURCES OF NEUTRONS: NOV 1 3 1964 MASTER Troyce D. Jones Health Physics Division Oak Ridge National Laboratory Oak Ridge, Tennessee Abstract--Acylindrical phantom of radius 15 centimeters and height 60 centimeters is homogeneously composed of H, C, N, and 0 with the com- position percentages present in standard man. Neutrons having the energy spectrum of fission sources are assumed to irradiate the phantom unilat- erally and bilaterally. The phantom is divided into 150 volume elements, and the average dose is obtained in each such volume element for each exposure situation mentioned above. The percentage of the average dose in various ranges of LET are given for selected volume elements. This detailed distribution of dose with LET permits the estimation of dose equivalent in each volime element and also provides the fundamental data for study of the correlation of biological effectiveness with LET. The concept of Relative Biological Effectiveness (RBE) was developed to estimate the biological effects of a new exposure situation in terms of past experience. The International Commission on Radiological Protec- tion (ICRP) and the National Commission on Radiological Protection (NCRP) have recommended that RBE of ionizing radiation be based on Linear Energy Transfer (LET) between the incident particle and the particles or medium which it irradiates. The RBE of radiation depends among other things on: 1. Rate of LET along the tracks of the ionizing particles 2. Dose level 3. Dose rate 4. Biological end point 5. Size and composition of phantom 6. The general situation during and after exposure(1) Thus, RBE may vary with different exposure situations. It is evident that dose level is not correlated closely with the LET distribution of dose; hence, these distributions cannot be represented by a single number. One concerned with study or treatment of neutron exposure needs the en- tire pattern of dose to interpret the spectrum of effects. There exists effects which directly reflect the exposure of a particular component, and in this case the local dose is important, but for other effects such as a depression of white blood cell count, the exposure of many compo- nents might be more important.[2] *Research sponsored by the U. S. Atomic Energy Commission under contract with the Union Carbide Corporation. Thus, in order to calculate the REM dose equivalent of radiation in tissue by heavy charged particles, it is necessary to know the values of LET. [3] Unfortunately, there exists no exact theory to determine these at the present time. When neutrons irradiate tissue phantoms, the dose will be delivered by recoil protons and recoil ions of the heavy elements (carbon, oxygen, and nitrogen), by inelastic collisions, and by thermal neutron capture resulting, for the most part, in the production of gamma rays. The energy deposited per elastic collision will vary from zero to the energy of the incident neutron. The energy transfer in a medium is due both to inelastic and elastic collisions. An elastic collision produces a recoil atom having an energy which is a fraction of the energy of the incident particle. cota The codes used consisted of a neutron code, O5R,[4,5) and a gamma- ray analysis code. The 05R code produces independent histories of neutrons. Each history is compiled, collision by collision, until the neutron escapes from the phantom or until its statistical weight, Wor drops below a predetermined low value, W, ... Initially, the neutron is given a statistical weight of unity, and after each collision the weight is decreased by multiplication of the non-absorption probability which is given by 1 - Onoranze Cross sections for absorption (on) and the total cross secti ,) are for the element with which the neutron collides. When W. drops below Wow, the neutron, provided that it has not escaped from the phantom, is subjected to a subroutine such that it has a probability, P, of attaining a weight, W. : W. x 1/P, and a prcba- bility (1 - P) of attaining a weight, W, = 0. *In the latter case, it is dropped from the calculation. In a group, the average statistical par- ticle weight is the same after as before the operation, although a number of the neutrons are eliminated. The histories are computed in an unbiased manner giving each neutron che chance to follow variable paths or inter- actions determined by the appropriate cross section.[6] Neutrons absorbed by the hydrogen (ny) reaction give birth to a photon of 2.2 MeV energy, and the pertinent information concerning this gamma is written on the mag- netic tape which serves as input to the second or gamma-ray analysis code, This second code traces the photon much the same as 05R traces the neutron, and it has provisions for the generation of secondary gamma rays. These gamma cross sections are taken from Grodstein(7] and McGinnies.[8] Once neutrons reach thermal energies, assuming they do so before any of the three killing processes eliminates them, they are treated as monoenergetic with the thermal cross sections being supplied by Frigerio[9] and Drozdo et al.[10] (Oncone : 2.75 cm , och = 0.0234 cm') ab The machine time on a 1604 CDC digital computer totaled 26-2/3 hours. A total of 90,000 neutrons was traced producing 62,432 photons, and these in turn produced 35,908 more which made a grand total of 189,340 indi- vidual histories analyzed by the two codes. The individual breakdown for the five noutron fission spectra treated in this paper are given in Table 1. Table 1. Neutrons and Gammas Traced to Approximate Various Spectra Neutrons Traced Gammas Produced Secondary Garmas Produced ORNL VO22 assembly 10,000 6,408 3,662 Yugoslav (Boris Kidric) 3,701 3,891 Argonne CP-5 Y-12 Accident 10,000 10,000 10,000 10,000 6,566 6,924 7,091 - 7,239 4,224 Godiva II 4,129 The accuracy depends on the number of neutrons traced, with 10,000 being adequate for most cases dealing with man-sized phantoms, but many more would be required for a mouse phantom. The LET of the recoil nuclei is not precisely known over much of the energy range relevant here since the range of velocities is such that the charge of the ion is not con- stant due to the fact that it may gain or lose electrons as it moves. The average rate of energy loss or LET for hydrogen, carbon, nitrogen, and oxygen as used in this paper is given in Figure 1. The LET curve for the proton was taken from Hine and Brownell,[11] while those for oxygen and carbon were taken from Brustad , [12] and the curve for nitrogen was obtained by Snyder[5] by interpolation between oxygen and carbon. While these curves may not be highly accurate, it is probable that they are entirely adequate to separate out fractions of the dose delivered in ranges of LET shown in Figure 1. It is fortunate that oxygen, whicl: con- stitutes 73 percent of standard tissue, has been studied in detail, but nitrogen, which constitutes only 4 percent, has not been determined as completely. Snyder[5] treats the use of these curves in the 05R code. The phantom (Figure 2) is considered to be composed of standard tissue[13] ignoring all except the four main elements which constitute 99 percent of standard soft tissue by weight. This yielded a medium of density 0.96 g/cm3. The phantom was taken to be a right circular cylin- der of height 60 centimeters and radius 15 centimeters. It was divided into 150 volume elements by cutting the cylinder by 4 planes perpendicu- lar to the axis of the cylinder, by 4 coaxial cylindrical surfaces with regular increasing radii, and by 3 axial planes at angles of 600 with each other. The cases considered in this paper all correspond to the phantom being irradiated either unilaterally or bilaterally by broad, parallel beams of fission neutrons. The bilateral cases were derived by assuming the number of neutrons incident in the y direction was equaled by those from the -y direction. By symmetry of the exposure situation, certain volume elements must have the same expected dose and cose dis- tribution, and the values were combined for greater statistical accuracy. Even with the reduction in number, there remain sixty different volume elements for unilateral exposure and thirty for bilateral exposure. The total dose, including the components from photons and the dose from the protons produced by the (np) reaction with the nitrogen nucleons and the energy imparted by neutrons to the various recoil nuclei of the phantom, was averaged over each volume element. This average dose in each volume element was subdivided into doses which were delivered in various LET ranges. The following spectra were chosen as representative of typical reactors: The Y-12 accidental neutron spectrum was produced by a critical assembly at aqueous 10,F2 solution 15 centimeters in height, and 25.4 cen- timeter radius The 235U density was 0.0259 g/cm3. The N(E) versus E peaks at about 3 MeV and falls to zero at 9 MeV. Figure 1. Linear Energy Transfer as a function of Particle Energy for H, C, N, and O Ions in Tissue UNCLASSIFIED ORNL-DWG. 63-4830 1000.0 OXYGEN --NITROGEN LET AS A FUNCTION OF ENERGY 200.0 Kovce CARBON _ 100.0 100.0 Kw KAN 76.4 KOLA 62.5 kW shekarzu Fig. 1, Page 5, . D. Jones i i 35.0 Kevin LET (Kevin) 25.2 KONZE MIYDROGEN 16.0 Kaur he Kevin الممل 1.8001 - .001 ool 10.0 100. ENERGY (Mev) FIG. 1 Y Figure 2. Geometrical Arrangement and Element Numbering System for Cylindrical Phantoms UNCLASSIFIED ORNL-DWG. 63-4831 207 w NUMBERING OF VOLUME ELEMENTS OF THE TOP AND BOTTOM TIERS 18 9 13 17 - VOLUME ELEMENTS NUMBERED BY i VOLUME ELEMENTS NUMBERED BY i + 20 VOLUME ELEMENTS NUMBERED BY i + 40 VOLUME ELEMENTS NUMBERED BY i + 20 - VOLUME ELEMENTS NUMBERED BY i Fig. 2, Page 6, T. D. Jones A A E ELEMENTS.O MOMENTE ELEMENTS.O NUMBERING OF VOLUME ELEMENTS IN THE CYLINDRICAL PHANTOM FIG. 2 The Godiva Il noutron spectrum is typical of a fast reactor system and shows essentially no neutrons of energy lower than 10 keV escaping the assembly. Its core consists of a bare 235U sphere of radius 8.7 cen- timeters, and the N(E) versus Ecurve peaks at about 0.5 MeV and steadily decreases so that it is essentially zero at 9 MeV. The Yugoslav (Boris Kidric) reactor assembly consists of a matrix of natural uranium rods 2.5 centimeters in diameter in Dg0. The reactor vessel has a radius of 100 centimeters and a height of 178 centimeters. This is a large thermal reactor exhibiting a near 1/E spectrum delow 100 keV. The spectrum is very soft and yields nearly uniform neutron production in the energy range 10°6 to 1.0 MeV but falls to zero at 10 MeV. ORNL 10,F, is typical of an intermediate reactor and consists of an aqueous 10,72 Solution of 235U density equal to 0.643 g/cm. The radius is 15.2 centimeters while the haight is 29.4 centimeters. Although an appreciable number of low-energy neutroris escape, the largest fraction of the dose is due to those neutrons above 10 kek. Many low energy neutrons are produced by this assembly. Argonne CP-5 biological port consists of a 4-inch bismuth shield over a h-inch uranium converter plate, (14) The N(E) versus E at the biological port behaves much the same as Godiva II but tails off much faster for energies greater than 1 MeV with virtually no neutrons escape ing at 7 MeV, Graphs of the neutron spectrum, distribution of dose versus depth for both unilateral and bilateral exposures, and distribution of dose with LET for selected volume elements for each of the five assemblies are contained in Figure 3 through Figure 33 on pages 8 through 38. Table 2 gives the values of dose versus penetration for unilateral exposure. All values of dose/incident neutron have been normalized to Y-12 because this spectrum showed the least amount of attenuation and more nearly approachod the theoretical spectruis given analytically by N(E) : Ae Sinhv28. [15] The ORNL 10,F, critical assembly was of the same nature (the geometry and uranium concentration were slightly dif- ferent), and closely approximated the Y-12 values. The dose contribution due to the heavy elements for Godiva II was only about 1/6 that of the solutions of Y-12 and ORNL 10,F2, and it was too small to be considered even a contributing factor in either the CP-5 or Yugoslav calculations. In general, the total dose in the ele- ments of the second tiers (volume elements 20 to 40 and 60 to 80) in- creased about 9.5 percent over that of those elements in the first tiers lements 1 to 20 and 80 to 100), and the middle tier (volume elo- ments 40 to 60), increased 10.5 percent in total dose over the values in the first tiers. This probably can be explained in terms of the number of collisions because fewer noutrons would be escaping from those ala- ments, while moro would be entering them. Figure 3. Y-12 Accident Neutron Spectrum 1- . . - . . : E ! . . .. .. ... . . . ... ' . . .. . . . , 7 . - - - - - ... ; ' A7--- - - - .*.*' - - - - - Fig. 3. Page 8, T. D. Jones UNCLASSIFIED ORNL -DWG. 64-9353 Y-12 ACCIDENT NEUTRON SPECTRUM N(E) NEUTRON ENERGY (MeV) Figure 4. Distribution of Dose With LET Y-12 Accident, Volume Element 1 UNCLASSIFIED ORNL-DWG 64-9350 DISTRIBUTION OF DOSE WITH LET Y-12 ACCIDENT VOLUME ELEMENT I PERCENT OF DOSE Fig. 4, Page 9, T. D. Jones للللللللللاه 0 20 40 60 80 100 200 LINEAR ENERGY TRANSFER ( KEVIN) Figure 5. Distribution of Dose With LET Y-12 Accident, Volume Element 17 UNCLASSIFIED ORNL-DWG 64-9349 DISTRIBUTION OF DOSE WITH LET Y-12 ACCIDENT VOLUME ELEMENT 17 PERCENT OF DOSE Fig. 5, Page 10, T. D. Jones OLLILULLI 0 20 40 60 80 100 200 LINEAR ENERGY TRANSFER ( KEVIH) Figure 6. Distribution of Dose With LET Y-12 Accident, Volume Element 20 UNCLASSIFIED ORNL - DWG 64 - 9351 DISTRIBUTION OF DOSE WITH LET Y-12 ACCIDENT VOLUME ELEMENT 20 ::.. 5, PERCENT OF DOSE 333 a.,.:.:6035 olema commandemedemadamamen door eenpelawaandaman ko namalowed o 20 40 60 80 100 200 LINEAR ENERGY TRANSFER (KEVINL) Figure 7. Distribution of Dose With Depth for Unilateral Exposure Y-12 Accident, Volume Elements 1-20 and 80-100 Fig. 7, Page 12, T. D. Jones UNCLASSIFIED ORNL. DWG. 649346_ UU DOSE vs DEPTH Y-12 ACCIDENT VOLUME ELEMENT 1-20 & 80-100 ABSORBED DOSE (rod /n/cm?) TTTTTTTTTTTTTTTT TTTTTTTTT --- TOTAL DOSE Y DOSE HEAVY DOSE -5 bo to 20 25 30 10 25 30 15 20 DEPTH (cm) Figure 8. Distribution of Dose With Depth for Bilateral Exposure Y-12 Accident, Volume Elements 1-20 and 80-100 Fig. 8, Page 13, T. D. Jones UNCLASSIFIED ORNL- DWG. 64 - 9347 DOSE vs DEPTH VOLUME ELEMENT 1-20 & 80-100 LLLLLLLLL 040 ULILL ABSORBED DOSE (rad / nicm?) To TTTTTTTTT Sea o 12 - --- TOTAL DOSE Y DOSE HEAVY DOSE 10 20 25 DEPTH (cm) * Figure 9. Godiva II Neutron Fission Spectrum Fig. 9, Page 14, T. D. Jones UNCLASSIFIED ORNL-DWG. 64-9375 100 GODIVA I NEUTRON SISSION SPECTRUM N(E) NEUTRON ENERGY (MeV) Figure 10. Distribution of Dose With LET Godiva II Assembly Volume Element 1 UNCLASSIFIED ORNL - DWG 64-9362 DISTRIBUTION OF DOSE WITH LET GODIVA I ASSEMBLY VOLUME ELEMENT I PERCENT OF DOSE Fig. 10, Page 15, T. D. Jones اااااااااام 0 20 40 60 80 200 100 LINEAR ENERGY TRANSFER ( Kevlu) Figure 11. Distribution of Dogo With LET Galiva II Assembly Volumo Clamont 17 UNCLASSIFIED ORNL-DWG 64-93 60 DISTRIBUTION OF DOSE WITH LET GODIVA I ASSEMBLY VOLUME ELEMENT 17 PERCENT OF DOSE Fig. 11, Page 16, T. D. Jones 20 200 hiloddol 40 60 80 100 LINEAR ENERGY TRANSFER (KEVI? Figure 12. Distribution of Dose With LET Godiv II Assembly Volume Element 20 UNCL ASSIFIED ORNL-DWG. 64-9364 DISTRIBUTION OF DOSE WITH LET GODIVA I ASSEMBLY VOLUME ELEMENT 20 PERCENT OF DOSE Fig. 12, Page 17, T. D. Jones LI ILIhhh 20 40 60 80 100 200 LINEAR ENERGY TRANSFER (KeV/H) ic. 222" Figure 13. Distribution of Dose With Depth for Unilateral Exposure Godiva II Assembly, Volume Elements 1-20 and 80-100 Fig. 13, Page 18, ND. Jones seslek UNCLASSIFIED ORNL-DWG. 64-9370 F DISTRIBUTION OF DOSE WITH DEPTH FOR UNILATERAL EXPOSURE GODIVA I ASSEMBLY VOLUME ELEMENTS 1-20 & 80-100 - TOTAL DOSE Y DOSE HEAVY DOSE ABSORBED DOSE (red/n/cm², Ō, TTTTTTIT 10 10. 5 Mo t 20 25 30 DEPTH (cm) Figure 14. Distribution of Dose With Depth for Bilateral Exposuro Godiva II Assembly, Voiume Elements 1-20 and 80-100 Fig. 14, Page 19, 7. D. Jones UNCLASSIFIED ORNL-DWG. 64-9371 DISTRIBUTION OF DOSE WITH DEPTH FOR BILATERAL EXPOSURE GODIVA I ASSEMBLY VOLUME ELEMENTS 1-20 en 80-100 TOTAL DOSE Y DOSE HEAVY DOSE ABSORBED DOSE (rad /n/cm2) 1018 20 25 30 DEPTH (cm) MV Figure 15. Yugoslav Accident Noutron Spectrum Fig. 15, Page 20, T. D. Jones UNCLASSIFIED ORNL-DWG. 64-9352 YUGOSLAV ACCIDENT NEUTRON SPECTRUM K N(E) - NW A on ovo 107 106 105 10 104 103 10-2 10 NEUTRON ENERGY (MeV) Figure 16. Distribution of Dose With LET Yugoslav Accident Volume Element 1 UNCLASSIFIED ORNL-DWG 64-9348 DISTRIBUTION OF DOSE WITH LET YUGOSLAV ACCIDENT VOLUME ELEMENT | PERCENT OF DOSE riz. 16, Page 2, T. . ccnes olibelli 0 20 40 60 80 100 LINEAR ENERGY TRANSFER ( KeV/H) Figura 17. Distribution of Dose With LET Yugoslav Accident Volume Element 16 UNCLASSIFIED DISTRIBUTION OF DOSE WITH LET YUGOSLAV ACCIDENT VOLUME ELEMENT 16 oooa PERCENT OF DOSE 1:36:.::;.:.,:.:.::.5 0 20 40 60 80 100 LINEAR ENERGY TRANSFER ( Kevin) MY + . UNCLASSIFIED ORNL mom www . . 655 20F2 . - - . .. . T WAY ir .. ! . 1 . : int TY TA 2 . - E' .. . 19 Figure 18, Distribution of Dose With LET Yugoslav Accident Volume Element 17 . - . T . - . LINEAR ENERGY TRANSFER (KEVIN) 2. 200 100 80 60 40 20 . ... Fig. 18, Page 23, T. D. Jones PERCENT OF DOSE VOLUME ELEMENT 17 YUGOSLAV ACCIDENT DISTRIBUTION OF DOSE WITH LET ORNL-DWG 64-9354 UNCLASSIFIED . 2 . w to piutto ****oris domes in America Vi a GS . M MAL L SITE CS d dhe **** * mentioned that the *********** E LIU 1 * . TE - - Si . . Figur. 19. Distribution of Dos. With LET Yugoslav Accident Volume Element 20 :.: . .. . opy . . . UNCLASSIFIED ORNL - DWG 64-9356 DISTRIBUTION OF DOSE WITH LET YUGOSLAV ACCIDENT VOLUME ELEMENT 20 PERCENT OF DOSE fig. 19, Page 24, T. D. Jones للللللللللام © 20 40 60 80 100 LINEAR ENERGY TRANSFER ( KOVIN) . .. .! * ? eir K Figur. 20. Distribution of Dose With Depth for Unilateral Exposure Fig. 20, Poze 25, T. 0. Jonos UNCLASSIFIED ORNL- DWG 64-9345 DOSE vs DEPTH YUGOSLAV ACCIDENT VOLUME ELEMENT 1-20 & 80-100 1099 ABSORBED DOSE (rad in /cm? i - - - - - - - - TOTAL DOSE DOSE ---- 1013LI 106 10 15 20 DEPTH (cm) 25 30 Fisura 21. Distribution of Dose With Depth for Bilateral Exposure Yugoslav Acaidant, Volume Elements 1-20 and 80-100 ..: . . . . . . - - . LOL . . . Fig. 21, Page 26, T. D. Jones UNCLASSIFIED ORNL-DWG. 64-9373 100% DISTRIBUTION OF DOSE WITH DEPTH FOR BILATERAL EXPOSURE YUGOSLAV ACCIDENT VOLUME ELEMENTS 1-20 & 80-100 TOTAL DOSE Y DOSE ABSORBED DOSE (rad /n/cm2 , DEPTH (cm) Figure 22. Noutron Escape Spectrum for ORNL VOZF, Assombly in - . . . * - - " "; 7. .. . , 1 - 1 -... ' 1 1. . . : - H - - 1 . . 7. : .. . 3 . . . " 21. , . . . 1 - . - - -. . !! . K . - ' . MI' i ' V W - *. - . . . :. EER - * * - 1 " - . * . . :1. . . . . Fig. 22, Page 27, T. D. Jonos UNCLASSIFIED ORNL-OWG. 64-9361 NEUTRON ESCAPE SPECTRUM FOR ORNL VO2 Fe ASSEMBLY 10 N(E) A . L . . 2V ar Uit RO 22 all 10o loro le lo NEUTRON ENERGY (MOV) k wa sasa kiszonkursataimuniteismai Figur. 23. Distribution of Dose With LET ORNL VOZF2 Assembly Volume Elanant. 1 . . . - WCW ***ang menstrua . Ron UNCLASSIFIED ORNL-DWG. 64-9367 DISTRIBUTION OF DOSE WITH LET. ORNL 10,F2 ASSEMBLY VOLUME ELEMENT I PERCENT OF DOSE Fig. 23, Page 28, T. D. Jones é ' . لللللللللاه 60 200 :,, 80 100 LINEAR ENERGY TRANSFER (Kevin) .. .. .. . . . Figure 24. Distribution of Dose With LET ORNL VOZFAssembly Volume Element 17 .- A - 21 .. . 2. 22 s 4 . UNCLASSIFIED ORNL-DWG. 64-9365 DISTRIBUTION OF DOSE WITH LET ORNL UO, F, ASSEMBLY VOLUME ELEMENT 17 PERCENT OF DOSE Fig. 24, Page 29, T. D. Jones © 20 40 60 200 80 100 LINEAR ENERGY TRANSFER ( KeV/H) TNHH .. : i Rs :-**** * man : ATA 4 AUX 27. 3 Zwi 22. SVM . : . - T :: . - - . . .- - . ..mwa.. Voluno Element 20 ORNL UO2 F2 Assembly Figure 25. Distribution of Dose With LEI . -r . . - - -- UNCLASSIFIED ORNL-DWG. 64-9368 DISTRIBUTION OF DOSE WITH LET ORNL VO, FASSEMBLY VOLUME ELEMENT 20 Fig. 25, Page 30, 1. D. Jones in- PERCENT OF DOSE - orewaer M od للللللللللاه 0 20 40 60 80 100 200 LINEAR ENERGY TRANSFER ( KOVINI 16 . "L" . . . •, . .. - ::* - - -i , i IN.. * . . . mii' . ... . Figur. 26. Distribution of Dose With Depth for Unilateral Exposure O RNL 1O2F2 Assembly, Volume Elements 1-20 and 80-100 " -- ' . . . ..... . . ... . .. . . . - . 1 . 1 . T - . . 1 . ' ! ' . - 1 - 1 T. . 2 r' -.',-:: - 7 T . 2 , . .- 1 - . '. www '. . . cr. . i . . . .. ".." cm . i ' ... ... ini i- 1 L UR .." n, it T , 1.. . ' . -- . . . 1 . .. . .. . 1. -. ini .. . . .. Fig. 26, Page 31, T. D. Jones .. . . UNCLASSIFIED ORNL-OWG. 64.9363 DISTRIBUTION OF DOSE WITH DEPTH FOR UNILATERAL EXPOSURE ORNL VOZF2 ASSEMBLY VOLUME ELEMENTS 1-20 & 80-100 TOTAL DOSE Y DOSE HEAVY DOSE ABSORBED DOSE (rad/n/cm², . . : T 15 DEPTH (cm) J. L ' r UU TA: i ' m .. CIAO . : . . -. H - : . - . - . T .-- S. - . . ' - | . :: A . . : . ! + . . . - - . : $ . - . 7.- - . + . - ... -- Hi . . ut . .. ** : .. . , ... 1 Wi - iu saire --, - . . 1. . . 3. w . - - ... 1 . ..? . . .... -**. . .! r .: 4 is . . Figur. 27. Distribution of Dose With Depth for Bilateral Exposur. ORNL NO2F2 Assembly, Volwe Elements 1-20 and 80-100 - 1 . 1 . ! w - - 1 . . 1 .. - ... --T . . "' . ... , TE ' . I . 12 1 TITI - . ' " ' .' "j! 1 x . . :: . . -- . .: . - . . 1 E " ' -" 77 .! * ' Y ? 1 - * # . 1 . . .. " 1. . ' . S } ' - . . t TT - i . . ! ". . i 1. . . . . . . 7 . . 1 . ..'' ' . : : ' " - .- . . - - '. - - . . .: :;!. - " 1 - . . S . . - - - Fig. 27, Page 32, T. D. Jones UNCLASSIFIED ORNL-DWG. 64-9366 DISTRIBUTION OF DOSE WITH DEPTH FOR BILATERAL EXPOSURE ORNL VO F2 ASSEMBLY VOLUME ELEMENTS 1-20 & 80-100 TOTAL DOSE Y DOSE HEAVY DOSE ULL ABSORBED DOSE (red /n/cm2) DEPTH (cm) AA 1 22. 2V , - - - the ..-- . .- . ... Figure 28. Argonne CP-5 Neutron Spectrum - - - 1- . '' T. - 1 .. .. . T.::. - -- . a' harron 1 , . ' . - - WA, . ini . .. 11, :, 1 iz id" . , ' . . L. ..! . , . 1 . . . , " 1 * :. . . .. . '1 1 Y S . . " I' . . 1,, YU . ' ' * -. . . . - . . .. : / , ... . . . . . . i . .: _ 2 - H + .. " 1:49. Yra I " I" Fig. 28, Page 33, T. D. Jones UNCLASSIFIED ORNL-DWG. 64-9374 IO ARGONNE CP-5 NEUTRON SPECTRUM N(E) .. . NEUTRON ENERGY (MeV) ---... -.-armesser wer en mit institutions and maintaining .. . Sex. in. Figure 29. Distribution of Dose With LET. Argonne CP-5 Assembly Volume Element 1 ... 1 . . . .. Lal !! !" . TUT A . .. I N m : aniwthe woman and women and UX . EU UNCLASSIFIED ORNL-DWG. 64-9358 ir - SA SI DISTRIBUTION OF DOSE WITH LET ARGONNE CP-5 ASSEMBLY VOLUME ELEMENT I 7 . PERCENT OF DOSE Fig. 29, Page 34, T. D. Jones . o 20 40 60 80 100 200 . LINEAR ENERGY TRANSFER (Kevin) LE S . 14 VN RE . Figure 30. Distribution of Dose With LET As gonno CP-5 Assembly Volume Element 17 . . . : SERA Pin YKOV *INS WLUWIE W UNCLASSIFIED ORNL-DWG. 64-9357 DISTRIBUTION OF DOSE WITH LET ARGONNE CP-5 ASSEMBLY VOLUME ELEMENT 17 PERCENT OF DOSE g. 30, Page 35, T. D. Jones o 20 40 60 80 100 200 LINEAR ENERGY TRANSFER (KEVIN) . YAY ? A 7 . re.. . .' 14 .' **:: " . M W RUTA . " ! . : ris A T AIWir" is , i n . Aicin . Figure 31. Distribution of Dose With LET Argonne CP-5 Assembly Volume Element 20 . . . TAS .. . * V * . UNCLASSIFIED ORNL-DWG. 64-9359 .. DISTRIBUTION OF DOSE WITH LET ARGONNE CP-5 ASSEMBLY VOLUME ELEMENT 20 مبمممم PERCENT OF DOSE Fig. 31, Page 36, T. D. Jones للللللللللاه o 20 40 60 80 100 200 LINEAR ENERGY "TRANSFER (KEVIN) . LA . - - -- ' 'T . .. G . 1 . . ..' 1 w Figur. 32. Distribution of Dose With Depth for Unilateral Exposure Argonno CP-5 Assembly, Volume Elements 1-20 and 80-100 . iii..... ' *'.,-,. :: .. NUERSAY 1 MS ***** 1 . .. . ... : . . . . .. . ! " PS 1.' 12 . . ' . I . Ir . . 1 I! - . ) 1 ? 3 i . 36 . . . . THIN .: L ' 416 . Fig. 32, Page 37, T. D. Jones UNCLASSIFIED ORNL-DWG. 64-9369 BUTION OF DOSE WITH DEPTH FOR UNILATERAL EXPOSURE ARGONNE CP-5 ASSEMBLY VOLUME ELEMENTS 1-20 & 80-100 111 TOTAL DOSE Y DOSE : . 6 ABSORBED DOSE (rad /n/cm2, Oy ....... ::.** 6 o b 20 25 30 DEPTH (cm) . SH . 1 . AZ ASIAT WAS si W Tier A . .. . . oceanten w ir d i e meestesvereniging ***---- .*- mi.'.* .:.:.:. . . * "* - - - - ... . . . .. . .. Sies Figure 33. Distribution of Dose With Depth for Bilateral Exposure Argonne CP-5 Assembly, Volume Elments 1-20 and 80-100 .. .. . .. . 2 :.; . . . . 2 - -, Fig. 33, Page 38, T. D. Jones UNCLASSIFIED ORNL-DWG. 64-9372 F DISTRIBUTION OF DOSE WITH DEPTH FOR BILATERAL EXPOSURE ARGONNE CP-6 ASSEMBLY VOLUME ELEMENTS 1-20 & 80-100 TOTAL DOSE Y DOSE ---- 16 ABSORBED DOSE (rad /n/cm2) 10 15 20 DEPTH (cm) 3:- -. . . A 1 . - , . 74.. Table 2. Total Doso per Incident Neutron Versus Penetration for Unilateral Exposure (Values Normalized to Y-12) Spectrum 1.5cma (Average Penetration Depth) Sami 10cm 15cm 20cm · 25cm 28.5cm . . 8-12 : ORNL UO2F2. Godiva II Argonne CP-s Yugoslav . 1.00 .98 .50 :53 .30 1.00 .95 .62 •38 .21 1.00 1.00.. 1.00 .92 .97 ,97 ' .50 642 .33 31. .21 ...19 14 .10 .09 1.00 1.00 .96.2.00 .25 .22 .13 .13 .07 .09 • A3 7 X 1 . ; . in * z. . . 22 S 2 . I * 2 . r . . . 2 VE 1. . . . . 4. Su AL . 1 F . 2 Tii . NG . . . . , . RdX TY i " . It * . .. . 2 M . . . I! . - HE 14 . . I." .. . 1 7 * 17. .' r. 6 i . SA According to Ritchie(16) thuso calculated dose values may differ from experimental ones by as much as 30 percent in cusu wher, the leak aga spectrum has an extremely large number of noutrons below 100 kov, : This is due to the fact that certain dorimeter have a poor rusponse to noutrons of this enerx range. BIBLIOGRAPHY 1. W. S. Snyder, "Some Data on the Relationship of RBE and LET," U. 8. Atomic Energy Commission Report TID 7652, Book 1, p. 402. 2. W. S. Snyder, "Distribution of Dose and Dos. Equivalont Rosulting From Broad-Boman Irradiations of a Man Sized Cylindrical Phantom by Monoonergetic Neutrons," presented at the Annual Health Physios Society meeting. Cincinnati, Ohio, June 15-18, 1964. .. . 3. J. Neuf old and W. S. Snyder, "Solected Topics on Radiation Dosimetry," International Atomic Energy Agency, Vienna, Austria, 1961, p. 35. H. R. R. Coveyou, J. G. Sullivan: H. P. Carter, "codes for Reactor con- putations," International Atomic Energy Agency, Vienna, Austria, 1961, p. 267. 5. W, S. Snydor, "Biological Effects of Neutrons and Proton Irradia- tions," Vol. 2, International Atomic Energy Agency, Vienna, Austria, 1964, p. 3. - - - - - - 6. D. J. Hughes and R. B. Schwartz, "Neutron Cross Sections," Brookhavon Nationa.'. Laboratory Report BNL-325, 2nd Edition, Superintendent of Documents, V. S. Government Printing Office, Washington, D. C., 1958 , 7. G. W. Grodstein, "X-ray Attenuation coefficients from 10 kev to 100 Mev." National Bureau of Standards Circular 583, Superintendent of Documents, U. S. Government Printing Office, Washington 25, D. C., 1957. - - - - - R. T. McGinnies, "X-ray Attenuation coefficionts from 10 kov to 100 Mev," National Bureau of Standards Supplemont to Circular 583, Superintendent of Documents, U. S. Government Printing Office, Washington 25, D. C., 1959. 9. N. A. Frigerio, Phys. Med. Biol. 6, 541 (1962). 10. S. I. Drozdov, D. F. Zaretsky, L. P. Kudrin, and T. K. Sedalnikov, "2nd International Conference on the Peaceful Vads of Atomic Energy," „Vol. 26, Ganovas United Nations, 1958, p. 228. 11. G. J. Hine and C. L. Brownell, "Radiation Dosimotry," Academic Prus, Inc., New York, New York, 1958, Chapter 14. - 41 12. T. Brustad, Rad. Res. 15, 139 (1961). 13. "Measurement of Absorbed Dose of Noutrons, and of Mixturas of Noutrons and Gamma Rays," National Bureau of Standards Handbook 75, Superintendent of Documents, U. S. Government Printing Office, Washington 25, D. C., 1961. "Physical Aspects of Irradiation (ICRU Report 20B)," National Bureau of Standards Handbook 85, Superintendent of Documents, U. S. Govern- ment Printing Office, Washington 25, D. C., 1964. 15. R. L. Murray, "Nuclear Reactor Physics," Prentice Hall, Inc., Englewood cliffs, Now Jersey, 1957, Chapter 2. 16. R. H. Ritchio, H. B. Eldridge, and V. E. Anderson, "Selected Topias on Radiation Dosinetry," International Atomio Enarøy Agency, Vienna, Austria, 1961, p. 657. i . " . .. . - - - .2 DATE FILMED 1 / 19 /65 - LEGAL NOTICE - This report was prepared as an account of Government sponsored work. Neither the United States, nor the Commission, nor any person acting on behalf of the Commission: A. Makes any warranty or representation, expressed or implied, with respect to the accu- racy, completeness, or usefulness of tho information containod in this report, or that the use • of any information, apparatus, method, or proceso disclosed in this roport may not infringe privately owned rights; or B. Assumos any liabilities with respect to the use of, or for damages resulting from the As used in the above, "person acting on behalf of the Commission" includes any em- ployee or contractor of the Commission, or employee of such contractor, to the extent that such employee or contractor of the Commission, or employee of such contractor prepares, disseminates, or provides access to, any Information pursuant to his employment or contract with the Commission, or his employment with such contractor. END