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82 (primarily by welding) into an integral engineering structure. The structure must be designed and built by techniques approved by the American Society ~f Mechanical Engineers (ASME) Boiler and Pressure Vessel Code. 3.4.1.2 Early materials studies led to the development of a nickel-base %E- Poy, HastePloy-N, ~ Q use P with fluoride salts. As shown in Table 28, the alloy contained 16% molybdenum for strengthening and ehromium sufficient to impart moderate oxidation resistance in air but not enough to Bead to high corrosion rates in salt. This alloy was the sole structural material Table 28. Chemical csmpositfon of MastelBoy-N Element Content o€ alloy (wt X f Standard Modified Nickel Base Base Molybdenm 1Ej-18 1 1-1 3 Chr om 1 m 6-8 Iron 5 -b 0. I Manganese 1 0.16-4.25 Silicon 1 0.1 Phosphorus O.OB% 0.01 Sulfur 0. Q20 0.01 Boron Titanium 0.01. 0.801 Niobium 1-2 "single values are maximum amounts allowed. The actual concentrations of these elements in an alloy can be much lower, bThese elements art? not felt to be very important. Alloys are now being purchased with the small concentrations speeified, but the specification may be changed in the future to allow a higher concentration. b
: ....., . .’ -. ..WY used in the MSRE amd contributed significantly to the success sf the ex- periment. HQW~WX, two problems were noted with Hastelloy-N which needed further attention before more advanced reactors could be builto First, Haste1loy-N was found to be embrittled by helium produced directly from traces of ’QB and indirectly from nickel by a two-step reactiom. type of radiation embrittlement is common to most iron- and nickel-base alloys. The second problem arose from the fission-product tellurium dif- fusing a short distance into the metal along the grain Bs~undaries and em- brittling the boundaries. nis Considerable success was encountered in modifying the composition of Bastelloy-N ts sbtafn better resistance to embrittlement by irradiation. The key factor was to modify the carbide precipitate from the coarse type found itl Standard Bastelloy-N to a Very fine type. ‘Ehe p%eSeKXe Of 16% wolybdemaurn and 0.5% silicon led to the formation of a coarse carbide that had little benefit. Reduction sf the m~lybdenum concentration to 12X and the SiliCSrt content to 0.1% and addition of 8 reactive carbide former such as titanium or niobium led to the formation of a fine carbide precipitate and an alloy with good resistance to embrittlement by helium. Consider- able progress was macle in the scale-up of an alloy containing 2% titanium, but this alloy does not have sufficient resistance to intergranular cracking by tellurium. An alloy containing B to 2% niobium was fasted to be very resistant to cracking by tellurium and was produced in small commer- cia% IIleltS. The cOmpoSit%Qn Of the niobfWll-modif$ed alloy iS ShQwsl in Table 28. This alloy majntains good ductility up to the 46-ppm max3mm helium content anticipated in the wall of a molten-salt reactor vessel. In studying the tellurium embrittlement problem, considerable effort was spent in seeking better methods of exposing test specimens to tellurium. 1x1 the MSRE, the flux of the tellurium atoms reaching the metal was about atoms m”2 s-’, and this value would be 10n4 atoms m-2 s-l for a high-performance breeder. Even the value for a high-performance breeder is very mall from the experimental standpoint. For example, this flux would require that a total of 7.6 x 10-6 g of tellurium be transferred to a sample having a surface area of IO cm2 in 1000 h. Electrochemical probes were immersed directly in salt melts kn~~m to contain tellurium,
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P iii CONTENTS ....................
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CONCEPTUAL DESIGN CHARACTERISTICS O
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3 The primary purpose of this study
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.. .... . w..w c Y ... . r 5 2. GEN
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ii.... :.: ..... .,. \ ..... %& . 3
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addition StathQR would be required.
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!I \.... . , . ~ .... .. . . / I I
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... .. ...... . . . $i 13 Table 1.
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15 Initial scoping studies showed t
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.. . E 6> I S N 0.45 k- 0.50 B --.
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:.:..y ,. . . w, E9 The code calcul
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h 3. Additional 238Y is added as re
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...z,y .. . c .A, Table 9. Actinide
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';x.w' .... Relative power distribu
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........ . . . :..i 27 a Inner 2.54
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29 Table 16. Effect of neutron spec
Page 37 and 38: ob E 2 a 4 5 6 7 8 9 10 11 12 13 14
Page 39 and 40: .. . . . . . . . . . 'a# 0.1 0.2 0.
Page 41 and 42: 35 (Doppler effect), (2) changing t
Page 43 and 44: where Ci = relative delayed-neutron
Page 45 and 46: .... . . . . , c.y..p c "
Page 47 and 48: .... :...w . . . . . :, %. , dimens
Page 49 and 50: ,. ::.y ~. . .... , 40 0 43 1 2 3 4
Page 51 and 52: .,.,. . . ., , .. . . . . . . . %..
Page 53 and 54: .... ... . ....... . .%.W 3.3.1.1 C
Page 55 and 56: 49 Variation of fuel composition wi
Page 57 and 58: .. .*,p. . . . . . . . Table 25. Ph
Page 59 and 60: ;: c.... x. . w ..i 53 Table 26, St
Page 61 and 62: would be expected to have an equili
Page 63 and 64: .... . . . . :i ,.*,&s 57 Corrosion
Page 65 and 66: . ;;..,..I . . . . . . "LW 0 9 m -
Page 67 and 68: of the fissioned atom. ea ~arly ass
Page 69 and 70: 63 n e results of a program of solu
Page 71 and 72: 65 Table 27. Sources and rates Sf p
Page 73 and 74: operation of the PISRE. 67 analyses
Page 75 and 76: UP3/UF4 ratio would be possible. DM
Page 77 and 78: $ .p9 3.3.3.1 Preparation of initia
Page 79 and 80: 73 Contamination of fuel by seconda
Page 81 and 82: *w- through the walls of the primar
Page 83 and 84: 77 4 will apparently be necessary (
Page 85 and 86: such contamination. For a demonstra
Page 87: 8% 3.4 Reactor Materials Although s
Page 91 and 92: ..... i.. ....., . .Yd 85 QRPIL-DWG
Page 93 and 94: ... w . . .y and to salt containing
Page 95 and 96: With the different ~Bjectives of ns
Page 97 and 98: t.;$- ... quite different from thos
Page 99 and 100: 93 during noma1 operation. Minor am
Page 101 and 102: ............. . . .. . .=w as SSm,
Page 103 and 104: . . . :.w . . . . , 4. ALTERNATIVE
Page 105 and 106: .. . ... . . . . . . .. . . "W 3. T
Page 107 and 108: .,.. w .." by removing some uranium
Page 109 and 110: , . . . . . . , -c%w probably still
Page 111 and 112: and the ~ dvent (or carrier) salt a
Page 113 and 114: BO 7 TPle fuel makeup requirements
Page 115 and 116: 5. CQPIPIERCIWLPZATION CONSIDERATIO
Page 117 and 118: 11% At the close of MSRE operation,
Page 119 and 120: 12YS 75 22”” 955 30” 1””
Page 121 and 122: 115
Page 123 and 124: aa 7 some components in common with
Page 125 and 126: Ae eo un t No * Table 3%. Capital c
Page 127 and 128: - ,.,.,.,., p .. ..... . G is based
Page 129 and 130: 123 Table 34. Summary of annual non
Page 131 and 132: ...... . . . . ., x.:w* 4 i.. ... _
Page 133 and 134: E2 7 There are no detailed estimate
Page 135 and 136: 129 particularly if such activities
Page 137 and 138: . ~.........* . . . . . :*. ... . -
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. .. . . . . . . . ;.:w b 133 the i
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_... ..&/ ; .; with reactor scram m
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137 includlng $900 million for the
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139 The authors want to acknowledge
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. ... . .,.,.,.,.,. . , i.rc- q....
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.:. _.i .. ..... -.=* 45. A. L. Mat
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...... &;.& 3 14 5 74. W, R. Grimes
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p 103. 6. Re Hudson 11, CQNCEPT-5 U
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... . . . . . . . , . ,.Y&fl 149 ap
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Account No. -0- Three- digit digit
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.... ..
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156 77. He 6. MacPherson, Institute
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