Review of Molten Salt Reactor Physics Calculations [Disc 2]

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i 44 6. TWO-DmIONAL CAICULDIONS The reactor was described in R-2 geometry as shown in Fig. 6.1. (All dimensions on this figure are in feet.) Forty-eight mesh lines were used in the radial direction and 67 axially. me region compositions are listed in Table 6.1 and thelmain core densities are listed in Table 6.2. Region U, the center control rod, was treated as a typical fuel cell (Figure 5.1) with the fuel stream replaced by graphite. In the lower axial blanket (region U), each fuel tube was considered to be loo$ INOR-8 between the core and the lower plenum. Region 18 is a vacuum region which is used to impose a black" boundary condition on the adjacent fuel and INOR boundaries. Region 19 is an annulus of fuel representing the four s*ets of entrance and exit fuel pipas at the bottom of the reector. Where possible, reactor dimensions and volume fractions were made the same as in the previous calculations (case 555). The nine-group neutzon diffusion equations were solved with the ASSAUIIT code.' A value of = Oig5 was obtained. The decrease in \ bff of 0.05 compared to the previous calculations is entirely attributable to a 215 higher thorium resonance integral used in our calculations. A f'uel search calculation was then made on the 23% concentration in the fuel stream until the reactor was just critical. A 23% concentration increase of 13.s was required to raise %ff to unity. A segionby-region neutron balance forthe critical configuration is given in Table 6.3. Only about 0.006 of the absorptions per fissile absorption occur outside the sllrroundhg blankets, indicating optically thick blankets. In fact, the axial leakage is so small that the axial blankets could be made samewhat thinner without affecting the neutron economy. However, about 0.005 neutrons absorbed in the lower axial bLanket are captured by INOR. This loss in breeding ratio might be avoided if it is possible to extend the graphite f'uel tubes below the core about 6-12 in. before mung the transition to INOR. The power density is very nearly in a Jo distribution radially and a cosine distribution axially, as shown in Fig. 6.2 and 6.3. The radial distribution corresponds to the mid-plane of the core, and the axialtraverse was made near the center of the core at r= 17 an. Power densities n W /- w z - U
- id i 45 am. UD. 664Ob9 t H b 0 t 1 Fig. 6.1 MSBR Reactor Model in R-Z Geometry I
Page 1 and 2: OAK RIDGE NATIONAL LABORATORY opero
Page 3: 3 . CONTENTS Intmduction ..........
Page 6 and 7: 6 The cross sections selected were
Page 8 and 9: 8 2. QF RESULTS AND FECOMMEIPDATION
Page 10 and 11: 10 2. The average '1 of 235U was 1.
Page 12 and 13: The power distributions obtained in
Page 14 and 15: 14 3. ao6S SECTIONS For the most pa
Page 16 and 17: Table 3.1 (cont 'a) mUclide ua(2200
Page 18 and 19: I Table 3.1 (eont'd) Nuclide Ua(220
Page 20 and 21: Table 3.2 20 (cont'd) W i Absorptio
Page 22 and 23: 22 on an average fuel salt temperat
Page 24 and 25: 24 28. 29 9 30 31 32. 33 34 J. Halp
Page 26 and 27: 26 Fig. 4.1 kclide Chains Used in b
Page 28 and 29: ’ 28 Table 4.1 Yield F’ractions
Page 30 and 31: 7.5249"7 30 Table 4.3 Fission Produ
Page 32 and 33: 32 Table 4.5 (cont'd) U kclide .,(Z
Page 34 and 35: I The infinite-medium code M-GAM wa
Page 37 and 38: Table 5.1. Figure 5.1Materials Zone
Page 39 and 40: 39 Table 5.3. (cont'd) Nuclide Pure
Page 41 and 42: * u E of these dips and elastic res
Page 46 and 47: 46 !Cable 6.1 Region Composition a
Page 48 and 49: 48 Table 6.3 Region Neutron Balance
Page 51 and 52: References. 1. D. RI Vondy, T. B. F
Page 53 and 54: 53 Table 7.1 Neutron Balance by Nuc
Page 55 and 56: ,- i 55 i !
Page 57 and 58: ~ . -. I . . ... ) ~ ,..I ........
Page 59: A DISTRIBUTIOl 1-5. DTIE, OR 6-15.

Review of Molten Salt Reactor Physics Calculations [Disc 2]

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