. . LOFT ORNL P 1480 : de . . . . MICROCOPY RESOLUTION TEST CHART NATIONAL BUREAU OF STANDARDS - 1963 ORNL-D-1480 MASTER P HEATING IN INFINITE CYLINDERS BY UNIFORM GAMMA SOURCES* H. C. Claiborne and C. W. Nestor, Jr. Oak Ridge National Laboratory Oak Ridge, Tennessee - 2 1965 AJG As an aid to the reactor designer concerned with gamma heating in olamonto that may be approximated by long cylinders, we have integrated the point kernel describing the transfer of gamma energy for the case 01? sources distributed uniformly throughout a right circular cylinder of infinite length. Since the coefficients were available?,2 for a third- degree polynomial representation of the energy absorption buildup factor, we chose this representation and were able to reduce the solution to a . rooulthas trau dhe fachadw age Homployect or contract report. LEGAL NOTICE – od Counterto TWI roport was prepared uu nocoon of Government sponsored worthMatthar do Outed oth borada contaband be the report, or dat het, mor the Counterton, nor any parta acting a bolo de contesto: A. Maka mynuty or representados, corrend or luptetwo mapect to ou acou- peratus, methods or process dechowed ta de report Buy not infring a h B. Assumes may labutin na mapoot to the wool, or for dames ployee or contractor of the Commutan, or Uployee of mch contractor, to the extent that un oluylaformation, appunto, method, as proones decid bad uployu or contractor at the Commission, or deployee of mucha contractor pogaras, ma diamentelor, or promotes noches, may lasormation part woh the Commutatou, o Ma neployment will ma contractor. the moy, completed, or al my taformation, peinately owned notas ar dodh dhe bone, mol single numerical integration involving each term in the buildup factor expansion by placing the origin of the coordinate system on the field point P (see Fig. 1). In addition, we obtained an analytical expression for the contribution from the linear term in the expansion. With the coordinate system as shown in Fig. 1, we express H(r), the energy deposition resulting from a uniform isotropic monoenergetic source S (Mev/ sec.cm) as a H(r) = 4Sug J J * or Thila).. B (up) e la dz n dn da n=0 2-0 40102 where RELEASIED FOR ANNOUNCEMENT IN MUCLEAR SCIENCE ABSTRACTS. = linear energy absorption coefficient, cm-2, H = total linear attenuation coefficient, cm-, Mela) = VR2 ge sina a'- r cos a, the maximum value of 1 for a particular a (see Fig. 1), cm, Research sponsored by the U. 8. Atomic Energy Commission mader contract with the Union Carbide Corporation. nearnown ::.;. TO THE AEC AND ITS-CCKTRÁCFCRICKS .. to - povna + z2, the distance from source point to field point, cm, mlup)", the energy absorption bul.ldup factor, dimensionle88. Upon substituting the above expressions for B (up) and p into Eq. (1), . sories we obtain of myla) H(r) - - . Inform - VO2 + 22 om dz n dn da , (2) e v212-m az um - where the z and n inside the integral are now expressed in mean free paths and & are the coefficients of the polynomial representation of the buildup factor. For convenience in the integration we now define - ; -- - - me tha + z2 (n) w dz, žo (ne + 2232-1 and if we let n² + z² = n²t² , we have eent at ine er der etter <(n) = 4 * Rei .vngis at m By comparison of Eq. (4) with integral representations of the modified Bessel functions of the second kind,\,(x), we find that . n zkiewinne Fo(0) = *12(1) = 5 x (t) at, Fi(n) = K (n), Fa(n) = nki(n), F3(n) = 72k (n) + nki(n). We then express the heating, H(r), in the form u H(s) - I mi ovo(s) and using Egs. (5) through (8), we obtain3 Vo(x) = 1 - * * Kuzcumq) da, *a(r) = 3 - * urme Kawma) da, va(x) = Vo:(0) - test cura de K, Curma) da , · 63() - ve(r) - Boat (uno bo ku Cuma) a. (13) In addition, if we write an expression for 8(r) in the coordinate system centered on the axis of the cylinder, we have (r) K(1) de xi dr' (14) Using the addition theorem for K (n) and performing the e integration, we Pind that UR "(t) = \,(0) Le PPI (rº) dx' + I,() , x5, (r”) dr". (15) After integrating with respect to rl and using the Wronskian identity, : . X (x) Iz(x) + Kj(x) I (x) = ; we have *(T) = 1 - HR Kx (HR) I (ur). (16) At r = 0, the point of maximum energy deposition, Mala)-- R,and on integrating Egs. (10) through (13), we have with a similares medicini, Akan tentakelis kartu su de comedor . V. (0) - 1 . Kialur) , (17) vi(0) - 1 - UR Kz (AR) , (18) (19) va(0) - 4260) - Suge K. (NR) *360) – veco) - Sun 13 (ur). (20) The average energy deposition rate ħ is given by R. 1- SU(=) = dr , H(r) r dr , (21) which we express in the same form as Eq. (9), with the vi(r) replaced by Tm. The function T. 18 just the collision probability given in analytical. and tabulated form by Case et al.5 In addition we have by integrating Eq. (16), Ti = 1 - 211(UR) Kı(UR). (22) The results of numerical integration of Eqs. (10) through (13) and numerical integration to produce the functions are shown in Fig. 2 af functions of cylinder radius. We were able to obtain excellent agreement between our numerically integrated it and the tabulated values, and also between the results of the numerical integration for vi(r) and Fi and analytical solutions (10) and (13). Tabulated values of the vn(r) functions and the tm are available on request, &s are the FORTRAN-63 programs used in the calculations on the CDC 1604A. References 1. CAPO, M. A., "Polynomial Approximation of Gamma-Ray Buildup Factors, for a Point Isotropic Source," APEX-510 (1959). 2. TOBIAS, M. L., D. R. VONDY, and M. P. LIETZKE, "NIGHTMARE – An IBM 7090 Code for Calculation of Garima Heating in Cylindrical Geometry," USAEC Report ORNL-3198, Oak Ridge National Laboratory (1962). 3. For a definition of the Ki, (x) functions, see, e.g., W. G. Bickley and J. Nayler, A Short Table of the Functions Ki (x), from n = 1 to n = 16, Phil. Mag. 7, 20, 343-347 (1935). 4. WATSON, G. N., Theory of Bessel Functions, 2nd Ed., p. 361, Cambridge U. Press, London (1952). 5. CASE, K. M., F. de HOFFMAN, and G. PLACZEK, Introduction to the Theory of Neutron Diffusion, Vol. I, pp. 31-35, Los Alamos Scientific Laboratory Los Alamos (1953). ., . . . . . . ... nour -.- ) الي || | FIGI; GEOMETRY FOR INTEGRATION OF POINT KERNEL مممم..- ..- ۰۰۰۰۰۰۰ : . ۱۰ه-۱۰ : ... .. : . ....- - -- - . . LIDL 0011 OIBI L DOOD : U1 001OWO D R00000000 NON 100000000 U CON BUDII U11 LODIO 20.000IDO UUUU 100 DOO 2000 DOIDDIII 1000Mb ID00DIDDIDDIO MINIDIDID O DOU . D. wa00000DIDI0DD UNIIDU IIPOIIIII ODS MIDD 10101010 DON.10. . . . . JUDI OILO 100100 011 00 0011 000 ODIO IMIDIP 0 .10 PIDULUI LOTU W100 -0.ONIDODIO DUT DOO ID QODITIMIT 00000000000000000000000 DOIDUDNODUDUDDDDDDDDDD on8XI0p 01 10000001.... ONUMO DIDDOOMIPOOD DANM100IDROOI IDDIDDWUDU01 MINOWDDIDDITITOUTVIDUTIDO NU0011 IUDIO001TUU WUNDUOLIUDDIDUNUTTUU 000 IDPOOTTO DIDOL UDDIDDODONU M OTO0100 ODOTTO bodde DODO ID ROPONITO. . PONP. DI 1001 00011 110DUU CU UULI 000 0000 On JOU I W INDOUDOT WY UVC TUU 000000 COM IMU0 0110000. 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