Document LgzzmLq4pZXDZ3Dz960GwpnoX

HAN ABOVE ihowi layout el three turbinegefterotori on drculor platform, with other MIAVY-WAT1R-COOUO RIACTOR Itwfi It (team generator*, which evppty three M-rne turbine* wllb 100-plo eatwreted itiam, Detlgn mlnlmliei heovy-waler need* Control rodt maintain f>**0 C^OcvJtr* trmp ^ -- SenamacAamtm Pfttlurt rtfa/afor t _ ^ control OfO-aomp tfittd FLOW CIRCUIT! OF UOUIA-COOIFD BFACTOR need tontrolt for tafa oparalloti. Bypaee around turbine lead* *tem to condetuer on e eudden load drop and on lew lead* two right-circular graphite cylinder* with adjoining end facet parallel to each other on the same center line. Theae cylinders contain natural-ura nium tlugt arranged In a lattice. The' alug channels parallel the cylinder ' axea. The cooling got (helium) enter* the small gap between the two cylinders and divides Its flow outward through ' the two reactor sections. A pressurised steel shell encases this assembly. The two core sections, each 35 ft dia and 10 ft thick, contain about 98$ tons of high-purity high-density graph ite. About 500 tons of lower grode carbon surrounds the core sections and acts as a reflector. Uranium-metal fuel slugs have a center hole and flns resting on the slugchannel surfaces. It was assumed heat generates uniformly within the metal, and flows uniformly from all parts ofthe surfaces. Maximum metal tempera, ture is limited to 1000 P to preventphase transformation at 1200 P. More reactor power could be realised by de veloping an alloy and casing that could withstand internal temperature of about 1300 P. Coolant. Helium was selected be cause it has no chemical-eombination properties with uranium and has a J zero neutron-absorption cross section. Pressurising the helium to 10 atmos pheres reduces the power needed to transfer a fixed quantity of heat Booctor Shall. Openings in the 44. ft-dla sphere allow feeding uranium slugs into the graphite core. Tubes connect the end of each fuel channel in the graphite to fittings in the sphere well. Special closures prevent helium loss at 10 atmospheres and 750 F. Other openings allow circulating helium through the shell, inserting con trol rods and instruments, removing irradiated uranium slugs. Shielding and Vantllotlon. A con crete radiation shield (having the shape of a modified Quonset hut) com pletely encloses the reactor sphere. Ten feet from the sphere charging face a vertical fl-ft-thiek concrete wall, sup ported on rollers, moves with ex pansion of the charging tubes piercing it and the sphere. Six feet from the other side of the sphere stands the op posite 8-ft-thick concrete wall. Hot air inside the shield rises through a direct-connected stack. This maintains a negative pressure inside the shield, causing all air to leak into the shield. This air becomes radioac tive end must be diluted before being ' discharged to atmosphere. Charging and Discharging. Two channels et a time may be charged by a 6-cylinder charging machine in a se quence operation. The cylinders move ICFOIT ON ATOMIC ENftCV FOWEI THE STUDIES continued their charge into the sphere channels by helium pressure. The irradiated .jugs drop out of the core on the far aide and accumulate at the bottom of the sphere. They are removed through pressure locks into the storage canal [bCsted below the sphere. proctor Control. The more impor tant reactor instruments measure power level, reactor period, temperature and pressure ot helium. Manual and semiautomatic movement of control rods regulates the reactor. Automatic positioning maintains constant helium temperature at the boiler inlet. Remote indicators on the control board show their position. The rods ore moved with enough energy storage to operate them several times, over their full travel after an auxiliary power failure. Bight vertically mounted boron-steel safety rods drop into holes in the re actor graphite when released by nor- . malty energised clutches. They quickly stop reactor operation when (I) neutron density exceeds safe value (2) reactor gas-outlet temperature exceeds safe level (3) reactor gas pressure drops suddenly (4) auxiliary power foils (S) reactor period becomes short er than minimum value (6) heliumcoolant flow stops (7) automatic trip button Is pressed. Helium Cycle. Helium leaves the reactor sphere et 650 P to enter the boilers, Leaving boilers at 384 F it enters gas blowers to be returned to the.reactor. Multiple take-offs end the need (or reasonable duct sizes require 12 separate circuits for the helium. Hollars are -straight-through types in which economiser, evaporating and superheating' sections are combined into one continuous pass. A 3Vi-in. feedwater line enters the shell through a thermal sleeve and connects to a 6in. inlet header. From this header 48 one-in.-OD tubes spaced on 2-in. hori zontal centers form a bundle of 48 hairpin loops spaced on 2-in. vertical centers. These tubes terminate In an B-in. steam header. There ore 95 loops in each of the circuits. The shell is bout 13 ft dia and 23 ft, 6 in. long, with 6-ft-dia flanged openings at both ends to which the helium ducts con nect. There are 12 boilers, although 10 can develop full reactor power. Eoch boiler can produce 90,600 lb per hr of 2S0-piig 52S-F steam from 109-P feedweter. This assumes 2.S-in.-Hg back pressure on main turbine. Howors. The oxial-Row-type heli um blowers must run ot constant flow. Flow variations must equal capacity of one blower. Load variations with a fixed number of blowers running are made by varying helium temperature out of the boilers. Twelve blowers, 75.000 cfm each, supply total helium flow. Half the blowers are steam-tur bine driven, others ore electrically driven. Over-all dimensions of blower and drive are about 20 ft long, 9 ft wide, 9 ft high. While helium does not become radio active, it might carry particles of ac tive materials. Removable concrete blocks. 2 ft thick, used (or shielding permit maintaining boilers and blow ers. No radioactivity transfers from helium to steam in the boilers. Underground storage tanks, occupy ing 45 acres, store the helium. Miscel laneous buildings with total area of 15.000 sq It house the valves, controls ond purifying equipment. Turblne-Oonerolor. The 650-F he Reocter structure Fuel boding, tube) InUrumentotlon ond control) tow graphite, 2400 ton* Finished graphite, 2100 lent, machined and installed Elevator), charging equipment Total reactor ottembty Bailer), It, eccetcorla* lerblne-generoier, 60 mw, octettoriet Stock, 500-tt high Wolar tyitem, dacontominollon areo, wotla itoroge Budding) ' Helium tyelem Electric laciiitlei Miscellaneous, cite, land, ek Contlaganciei Engineering. J% Ovaiheod, 14% Grand total S 1,940.000 2.000,000 1.200,000 1,000,000 1.260.000 300,000 t 7700,000 4JMJOOO 003,000 ,300,000 100,000 4,200.000 , "f,630.000 1734,000 023.000 4.420.000 1700,000 4730,000 140,000.000 Reactor Haavy.wofer fyitem Heavy water |Sfl] par lb) Helium tyitem Total reactor assembly t 3.146700 3.172,000 41700,000 330700 148,346,000 Steom.generator ptont Terblne.generotor ptanl (240 mw) Structural plant Miscellaneous power equipment Clactric laciiitlei 4,176700 14,265,000 10.024,000 342.000 3719700 Site, ether land cacti Miccelloneoui, yard improvement) temporary construction teieorch ond development Contingent!#) Engineering Overhead, 15% 1,625700 2740.000 2700700 6700,000 4700700 15743700 Grand total H 16,000,000 lium temperature led to selecting 52S F for steam leaving the boilers. The 265-psio pressure kept exhaust moisture below 14.7%. At 2.S-in.-Hg back pressure the turbine generates 61,700 kw gross at 14,500-Btu-per-kwhr heat rate. Electric auxiliaries use 15,000 kw, leaving a net of 46,700 kw. Steam auxiliaries use an equivalent 12.000 kw. Plant Control. Automatic controlrod adjustments hold reactor heliumoutlet temperature to 750 F. Adjust ing feedwater flow varies the boiler rating, and the boiler-outlet helium temperatures. Boiler output determines kw generation. Steam temperature varies from S7S F at full load to a theoretical 650 F ot zero load. A steampressure controller regulates the tur bine governing valves. To achieve high plutonium produc tion jthe reactor should be held at full power roting even while electric gen eration, is reduced. A steam byposs line around the turbine to the conden ser dissipates the heat In excess of that needed by the turbine. The bypass automatlcally protects the reactor in event of a turbine tripout. Costs In Table I ore based on con ditions In the Middle West. They do not include costs of fuel fabrication and processing. Assuming a net output of 45,000 kw, the installed cost aver ages $889 per kw. llqgld-Coolod Roactor. This cylin drical unit, enclosed in a spherical steel shell ot 800-psto pressure, uses heavy water oo coolant, moderator and reflector. Fuel assembly Is made up of separate elements, eoch consisting of o group of uranium slugs in o thin metol casing. These ore placed In ver tical, cylindrical channels. Heat from the uranium pastes through the thin metal clodding to heavy water, pass ing In a vertical direction upward. Heavy water flows between end through the fuel channels. The flow be tween channels acts as the moderator; traveling relatively slowly, it dis charges through the control-rod assem blies. The fuel elements hanging verticolly in the channels sre charged ond-' discharged through the cylinder top. Puel-element maximum'surface tem perature is 46S F when reactor-outlet heavy-water temperature is 440 F. An economic analysis showed 440-F heavy water out of reactor and 180psio steam pressure to be best. This develops 1064 mw of heat in the re actor. The heavy-water system mutt run at 800 pita. A 25-psi pressure drop In the reactor develops 25-ft-per-sec water velocity. A helium-blanketing system pro tects heavy-water surfaces in the re- Wtr 1933 REPORT ON ATOMIC ENERGY 103