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-32- 6. CELL, A GENERAL ONE-DIMENSIONAL MULTI-GROUP CROSS SECTION CONDENSATION COLLISION PROBABILITY PROGRAMME A constantly recurring problem in reactor physics is the proper determination of effective or homogenized, macroscopic, few-group cross sections for sometimes complicated geometries with a great variation in spatial flux spectrum. These equivalent cross sections are later used in, for example, diffusion theory for over-all calculations. A usual procedure for these problems is that of using a sufficient number of energy groups for the whole problem. Sometimes this method requires a lot of groups and takes up much computer time. Instead the problem can be split into subproblems, where the space and especially the detailed energy-dependent flux distribution is calculated once and for all that provides space-dependent few-group cross sections foi application in the original over-all problem. The prescribed method ensures that the few-group cross sections are determined with the correct shielding and, as far as spectrum conditions are concerned, in surroundings that correspond to the actual surroundings in the over-all picture. For treatment of regions with strong flux gradients and large absorptions, which occur in, for example, control rods, a diffusion theory treatment is insufficient, and a more exact integral transport theory calculation is required. This section describes the cross section con>i::-.,ation programme CELL. By means of a one-dimensional, multi-group collision probability method it solves the detailed space-dependent flux spectrum problem, which in its turn is applied for arbitrary space and energy condensation to fewer groups. Furthermore the standard flux solution procedure SOLU and the employed convergence accelerating methods are described. 6.1. The Collision Probability Equation The multi-group collision probability equation has the following form for the thermal range (ref. 26 ): nr ng
- 33 - the remaining signs are used as follows: 1 * g * ng energy group index 1 * i * nr one-dimensional mesh index V. volume tf ^ neutron flux S. E source density distribution from fast-energy range t ? 2.6-g P.£. total cross section scattering cross section from group g 1 to g first collision probability in region i per source neutron in region j . The scattering cross section £,£' ^ as well as the total cross section E « = I« u* 1 *• g.=1 where I jp . is toe absorption cross section, should be transport-corrected by means of the method in section 3. If the whole spectrum is considered, the source density distribution s^ = xx. g 2, g'=l F j g »/ < 6 - 2 > K eff the remaining signs are used as follows: X, g neutron fission spectrum »E f, neutron production cross section
Page 1 and 2: i Risd Report No. 235 S •S s Dani
Page 3 and 4: December, 1970 RisO Report No. 235
Page 5 and 6: - 3 - CONTENTS Page 1. Introduction
Page 7: - 5 - Page 13. Summary and Main Con
Page 10 and 11: - 8- A combined unit cell and over-
Page 12 and 13: - 10 3. THE LASER - CROSS COMPLEX F
Page 14 and 15: -12- jg. g = £g. g . E g > (3 2) w
Page 16 and 17: - 14- where Q g (r) O fer reactivit
Page 18 and 19: - 16- D 6 c* 2J _ x 2A. w, j (4. 9)
Page 20 and 21: - 18- vectors: »j = Vi M "' F 'j-i
Page 22 and 23: - 20- (H(L„)+ u - l) 2 = 11 (LI u
Page 24 and 25: - 22- duced from equation (4.30):
Page 26 and 27: -24- be seen from the slope of the
Page 28 and 29: - 26- 5. DBU, A TWO-DIMENSIONAL MUL
Page 30 and 31: 28 set of cross sections, regardles
Page 32 and 33: -30- 5.3. The DBU Programme The int
Page 36 and 37: - 34 - k .. effective multiplicatio
Page 38 and 39: -36- h gTh E^-*S2 , (6.8) li'Msh D
Page 40 and 41: - 38- into a number of time steps d
Page 42 and 43: - 40- & - 0. A modification was per
Page 44 and 45: -42- 8. CDB, A COMBINED CELL COLLIS
Page 46 and 47: - 44 - programme. The problem with
Page 48 and 49: -46- treated in an approximative wa
Page 50 and 51: -48- Microscopic cross sections can
Page 52 and 53: - 50- column was 230.05 cm and equa
Page 54 and 55: -52- 10. UNIT CELL CALCULATIONS Mic
Page 56: - 54- with the homogeneous B-l tran
Page 59 and 60: - 56 The calculated and measured ur
Page 61 and 62: - 58- This section describes the av
Page 63 and 64: - 60- The Zr followers surrounded b
Page 65 and 66: - 62- within the core, whereas DBU
Page 67 and 68: -64- 238 on the local flux spectrum
Page 69 and 70: 235 The calculated diagonal U - 66-
Page 71 and 72: - 68- 235 For core locations G4-C-f
Page 73 and 74: - 70- The associated average power
Page 75 and 76: - 72- 239 240 ?41 The spent Core II
Page 77 and 78: - 74- The corner fuel rod Phase II
Page 79 and 80: - 76- 13. SUMMARY AND MAIN CONCLUSI
Page 81 and 82: - 78 - 15. REFERENCES 1) H. C. Hone
Page 83 and 84: - 80 - 28) F. W. Todt, Revised GAD,
Page 85 and 86:
- 82 - 16. APPENDIX The description
Page 87 and 88:
I - 84 - CEBU TIMS MACR DEPL. CEDI
Page 89 and 90:
86 - Table 2 Yankee unit cell descr
Page 91 and 92:
- 88 - Table 4 Yankee Core I beginn
Page 93 and 94:
- 90 - Table 7 Yankee control rod c
Page 95 and 96:
- 92 - Table 10 Yankee Core I begin
Page 97 and 98:
Table 13 Uranium inventories of Yan
Page 99 and 100:
- 96 - Table 15 Initial and final u
Page 101 and 102:
Table 17 Normalized uranium and plu
Page 103 and 104:
Table 19 Normalized uranium and plu
Page 105 and 106:
Location Table 22 Normalized uraniu
Page 107 and 108:
MAIN ORIGIN ALFA FATE J | RATE SLOW
Page 109 and 110:
CEB BDM)- ORIGIN ALFA DAPA STEP FID
Page 111 and 112:
MAIN FUICA _ , 1 ROMO 1 FLUC 1 REAC
Page 113 and 114:
Mesh lines Flux points V.Z.9 . X.R
Page 115 and 116:
tmj iKBtXIKB,) t« 1 «,,) s « k -
Page 117 and 118:
- 113 - X'' \X \ \ \ \ V li', V \ \
Page 119 and 120:
-113 I r / ••• h w«x !i ;.',
Page 121 and 122:
» U * P . ».'" P . -.»! P~. , *
Page 123 and 124:
- 119 - Th« positions of th« 305
Page 125 and 126:
- 1 21 - tf" 00 (O-1.855 eV) 4 6 8
Page 127 and 128:
- 123 - 48 44 40 36 - 32 28 24 20
Page 129 and 130:
- 125 - 0-1 = I 2 3 F^/Nf . MMMom (
Page 131 and 132:
o MM»ur«d Phatt I. n and in data
Page 133 and 134:
Fig. 35. U concentrations versus ac
Page 135 and 136:
- 131 - I0- 2 r- »"•I I 1 1 I 00
Page 137 and 138:
133 •O-'cr 10"' I i •o" = A ur'
Page 139 and 140:
Assembly FS Jk 18 2222 cm w 2 SW TT
Page 141 and 142:
- 137 - Assembly J 3 l. 0719 em 1.2
Page 143 and 144:
2 t -— i ^ —m~ ' Ir Canlrol 3 '
Page 145 and 146:
I I UO U» 106 104 102 too 098 . 09
Page 147 and 148:
.i 1 s i .o — LASER (asymptotic)
Page 149 and 150:
- 140 - Q6 OS r 0.7 ai • a § k I
Page 151 and 152:
147 - Control rods 2 Symmetric boun
Page 153 and 154:
Control rod pattern in relation to
Page 155 and 156:
Control rod pattern in relation to
Page 157 and 158:
-15$ - Rg.65. LASER - unit cell bur
Page 159 and 160:
-155 - Fig. 67. CELLcross siction c
Page 161 and 162:
R9 69 -157- TWOCHMover-all flu« so
Page 163 and 164:
- 159 - »ORIGIN »IBLDR COARP »IB
Page 165:
- 161 »ORIGIN »IEDIT »IBLDR CEBU
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