The prospects for very high-power electron accelerators for processing bulk materials

Radiat. Phys. Chem. 1977, Vol. 9, pp. 547-566. PergamonPress. Printed in Great Britain.

THE PROSPECTS FOR VERY HIGH-POWER ELECTRON ACCELERATORS FOR PROCESSING BULK MATERIALS

M.R. Cleland, C.C. Thompson and H.F. Malone Radiation Dynamics, Inc., Westbury, New York 11590

ABSTRACT The recent growth in the industrial usage of ionizing radiation has been stimulated by the development of reliable, high-power, electron beam generators which operate in the beam power range of i0 to i00 kilowatts. This high output has reduced the costs of radiation processes to about $0.001 per megarad-pound of product material. At this rate electron beam treatment is now less expensive than conventional methods for curing plastic and rubber products and sterilizing medical disposables. Future applications of electron beam radiation to bulk chemicals and waste materials will require even larger generators operating in the power range of i00 to i000 kilowatts to handle greater material thruputs. Unit processing costs must be further reduced because of the lower intrinsic values of these materials. Fortunately, lower unit costs will follow the development of more powerful equipment because most of the cost factors do not increase in proportion to the output power. This is demonstrated by analyzing the downward trends in radiation processing costs as the machine voltage and the beam current are increased. The Dynamitron accelerator technology is reviewed to show that this could be one method of achieving the projected power levels. Several large-scale radiation processes are discussed to show that applications can be found for electron beam systems operating in the projected range. INTRODUCTION The use of electron beam (EB) radiation in industrial processes is now expanding rapidly. This is largely due to the fact that EB processing has become less expensive than conventional methods for curing plastic and rubber products and for the suerilization of disposable medical devices. The cost breakthrough has been achieved via the recent development of high-power EB generators which have increased the product thruput rates and thereby reduced the treatment cost per unit of product. The rising cost of thermal energy is also working in favor of EB processing methods since the total energy demand for 547

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radiation treatment heat treatment.

is less than that consumed in the alternative

The trend toward more powerful electron beam generators is continuing in response to the needs of industrial users. This trend will further increase thruput rates and reduce unit processing costs for large volume applications and may soon open the door to the use of EB radiation on bulk chemicals and waste materials, especially those that now consume large amounts of thermal energy in conventional processes. Recent developments and future prospects for very high-power EB generators are reviewed in this paper. The downward trend in processing costs is analyzed and some possibilities for largescale applications are considered. PRESENT ELECTRON BEAM POWER RATINGS The useful electron energy range for material processing is from 0oi to i0 MeV. Lower energies are not useable because of insufficient electron penetration in solid materials. Higher energies are not acceptable because of the induction of radioactivity in the products. At the lower energies, high-power beams (50 to 150 kilowatts) are not practicable because the very high beam currents required would imply very high process speeds and severe window cooling problems. At the higher energies, microwave acceleration techniques would be required which have not as yet been developed for high average beam powerso At this time the techniques which can provide EB power in the 50 to 150 kW range are dc electron accelerators in the 0.5 to 4.0 M e V energy range. These are now made by four firms, Radiation Dynamics, Inc., High Voltage Engineering Corp., Nishin HV and Mitsubishi. RDI offers i00 mA ratings up to 1.5 MeV, 50 mA up to 3.0 MeV and 25 mA at 4.0 MeV. The maximum beam power is 150 kW at 1.5 and 3.0 MeV. HVE offers 100 mA beam ratings up to 1.0 MeV, 50 mA at 1.5 MeV and 25 mA at 2.0 MeV. The m a x i m u m beam power is 100 kW at 1.0 MeV. Nishin HV offers 60 mA at 1.0 MeV and 50 mA at 1.5 MeV, a maximum of 75 kW. Mitsubishi offers 20 mA at 3.0 MeV for 60 kW. Several other firms offer electron beam processing equipment with power ratings under 50 kW (i). PRESENT DYNAMITRON A C C E L E R A T O R TECHNOLOGY The Dynamitron cascaded rectifier system has b e e n described in detail elsewhere (2-7). It is a true parallel-input, seriesoutput voltage multiplier which converts high-frequency ac power into high-voltage dc power with good efficiency at all energies° In this system, radio-frequency power is capacitively coupled to the rectifier stages via a pair of semi-cylindrical electrodes which surround the rectifier column. The rectifiers are connected to a series of semi-circular corona shields which together form

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an inner, cylindrical envelope around the column. The corona shields perform the combined functions of receiving rf power from the driving electrodes, filtering the dc potentials and preventing corona discharges from the rectifier terminals and other highvoltage components. Neither capacitors nor transformers are required in the rectifier column. Therefore, the stored electrical energy in the column is very low and the risk of component damage due to spark breakdown is minimal (7). This is of critical importance in the voltage range above 2.0 MV. The rectifier column and rf electrodes of a 4.0 MV Dynamitron are shown in Fig. i. This is one of a series of research accelerators which are equipped with high-vacuum rectifier tubes. These tubes have a maximum dc current rating of 25 m A and operate at an output voltage of 50 kV dc per stage. The particle acceleration tube is mounted inside the column and is electrically connected to several intermediate potentials to stabilize the voltage gradient along the tube. This is a beneficial arrangement when accelerating a high-current beam through a long tube at energies abcve 2.0 MeV. The rectifier column of a 3.0 MV Dynamitron is shown in Fig. 2. This is equipped with solid-state rectifier modules rated at 50 mA dc. Each stage produces an output voltage of 50 kV dc, and 60 stages are employed to produce 3.0 MV. The acceleration tube is mounted inside the column as in the 4.0 MV model. The rectifier column of a new model is shown in Fig. 3. This unit employs full-wave rectification to deliver i00 mA of output current at 1.0 MV through two parallel-connected cascade circuits which are mounted within the same column structure. This machine uses standard 50 mA solid-state rectifier modules in each cascade circuit. The acceleration tube is mounted in tandem at the end of the column in this arrangement because the tube is shorter than the full-wave column and has a higher voltage gradient. POWER CONVERSION EFFICIENCY The power conversion efficiency of an industrial Dynamitron is typically above 60% at full output. This figure is obtained by comparing the electron beam power to the ac line power fed into the rf generator. The auxiliary devices such as the vacuum pump, the window cooler, the control console and the ozone exhaust blower have been omitted from the efficiency measurements. The power factor at the ac line feeding the rf generator is typically about 85~. Only the real part of the ac line power is used to calculate the conversion efficiency. The relationship between ac line power and electron beam power for the 3.0 MV-50 mA-150 kW machine is shown in Fig. 4. The initial line power required to generate the high voltage without any beam load is about 24 kW. This reduces the power efficiency with low beam output. The efficiency curve rises to a maximum value of 65% at ii0 kW and declines slowly to 62% at 150 kW of beam power.

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The shape of the efficiency vs. beam power curve is affected by the method of coupling the oscillator tube to the rf transformer which energizes the electrodes surrounding the rectifier column. If the impedance match between this tube and its resonant load is not optimum, then excess power will be dissipated in the oscillator tube and the efficiency of the accelerator system will be reduced. The maximum efficiency of the oscillator tube itself (a water-cooled triode) is about 80%. The additional power dissipation in the dc supply for the oscillator, the rf transformer and the rectifier modules reduces the overall efficiency to about 65%. THE PROSPECTS FOR LARGER DYNAMITRONS The first consideration in designing a more powerful Dynamitron accelerator is the availability of a larger high-frequency generator. Here the prospects are very good. The rf generator used with the 150 k W accelerator is over designed and has ample reserve capacity for still higher output power (see Fig. 5). The oscillator tube is rated for 375 kW max. dc plate input power. This would correspond to an ac line demand of 410 kW real power. At an assumed 60% conversion efficiency, a properly designed and matched accelerator system connected to this oscillator could produce a 250 kW electron beam. As far as high-power oscillators are concerned, the sky is the limit - so to speak. There is now available a larger oscillator tube rated at 750 kW max. dc plate input power (9). This could be used to drive a 500 k W electron beam generator. Then one might consider using a pair of these tubes in a push-pull oscillator circuit to double the beam output again to i000 kW. If and when such powerful machines are built, the technical challenges will p r o b a b l y be greater in the design of the high voltage generator or in the electron acceleration system than in the rf oscillator. The most likely approach for the high voltage generator would be an extension of the present full-wave, i00 mA design to higher energies. An objective of 2.5 MV-100 mA-250 kW would have a high p r o b a b i l i t y of success. The next step to 500 kW would present a choice between doubling the voltage or doubling the beam current. An important consideration which favors increasing the voltage is the design of the irradiation process. At a 500 kW power level the material thruput rate for low-dose applications would be very large and could be handled better by increasing the thickness of the irradiated material rather than doubling the speed of the conveyor which would be required if the beam current were doubled. From the standpoint of the generator design, increasing the voltage to 5.0 MV with a i00 mA beam load might require fewer changes in the electron acceleration system. The higher voltage could probably be achieved by simply making a longer rectifier column using more of the standard solid-state modules in the fullwave cascade circuit. The diameters of the rf electrodes and corona shields would have to be increased to provide more coupling

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and filtering capacitance than is now available in the 4.0 MV half-wave generators. The rf transformer would also have to be increased in physical size to handle the larger reactive current that would be drawn by the rf electrodes. Other advantages of the 5000 kV - i00 mA specification are that the standard electron gun and beam scanning system could be used. The greatest uncertainty would probably be the behavior of the acceleration tube with such a powerful electron beam. The optical properties of the beam would improve at the higher energy but problems could arise due to collisions of the energetic electrons with residual gas molecules inside the tube. The gas p r o b l e m could be overcome by providing auxiliary vacuum pumps at intermediate points along the acceleration column. Actually, one titanium ion pump at the high voltage end of the tube might be sufficient. The beneficial effects of ion pumping at the end of the tube have already been demonstrated when accelerating proton beams. The gas-scattering effects are stronger with protons than with electrons because of higher residual gas pressures in the acceleration tube (8). The next step to 1000 k W will be the most uncertain as far as the accelerator design is concerned. It would probably be easier to double the current to 200 mA at 5.0 MV rather than to double the voltage again to i0 MV. A compromise rating of 150 mA at 7.0 MV may be worth considering. However, the probability of sparking and the attendant risk of component damage will rise with increasing voltage. Therefore, the operational reliability of this type of equipment would be greater if the voltage were limited to 5.0 MV. Instead of developing new beam components with a 200 mA rating, it would be easier to install two acceleration tubes side-by-side inside the rectifier column of a 5.0 MV generator. Each tube could then deliver a i00 mA electron beam through separate beam scanning systems of standard design. For some radiation applications such as processing gaseous materials it may be advantageous to have a higher beam current at a lower voltage. The concept of multiple acceleration systems would be even more important in this case to avoid excessively high beam intensities. An alternative configuration for a m u l t i p l e - b e a m system is shown in Fig. 6. The high-current, high-voltage generator is located in the large pressure vessel on the left-hand side. The acceleration tubes are located in separate housing connected to one end of the main vessel. The high voltage power could be distributed via an SF 6 gas-insulated transmission line to any number of accelerator modules. The four-beam system shown here could be rated for 2.5 MY-400 mA-1000 kW while the beam modules would be built with standard I00 mA components. This discussion indicates in a general way the path that might

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be followed in developing very high-power in the i00 to 1000 kilowatt range. There any insurmountable obstacles to block the could probably be achieved using the same present line of Dynamitrons are based.

electron beam equipment do not appear to be way and these objectives concepts on which the

PROCESSING COST ANALYSES The cost analyses presented in Tables 1 and 2 have been prepared to show the capital costs and unit processing costs which are characteristic of today's electron beam technology when applied to continuous operations with high material thruput rates. An attempt has been made to include all costs which might be charged to the operation of a radiation processing system so as to get a realistic figure for the cost per pound or per kilogram of product material for a radiation dose of 1.0 megarad averaged throughout the material. The capital cost estimates for material handling equipment and for facility engineering and construction will vary from one site to another depending on the radiation process and on local design and construction practices. Similarly, the annual costs will depend on the depreciation schedule and on interest, labor and electricity rates which will vary with time and place. The figures shown are typical of high-power accelerator installations at this time in the United States. The cost estimates presented in Table 1 are for three Dynamitron models rated at 0.5, 1.0 and 1.5 MeV, all delivering the same beam current, I00 mA. The estimates in Table 2 are for three larger Dynamitrons rated at 25, 50 and i00 mA, all operating at the same voltage, 3.0 MV. The total capital costs for these six models are plotted against beam power in Fig. 7. Curve A for increasing current extrapolates to about $2.4 million for a i000 k W installation. Curve B for increasing voltage extrapolates to about $2.9 million at i000 kW. A m u l t i p l e - b e a m system will probably fall somewhere between these two estimates. A comparison of the processing cost rates given in the two bottom lines of Table 1 shows that the cost per pound or per kilogram of product diminishes as the beam power is increased by raising the accelerating voltage. This is due to the fact that most of the cost items (except for the electrical power) do not increase in proportion to the voltage. A comparison of the bottom line cost rates in Table 2 shows a result similar to Table i, that is, the processing cost per unit of product weight diminishes with increasing beam power as the beam current is increased° These six processing cost rates are plotted against beam power in Fig. 8. It can be seen that the downward trends of the processing cost rates are about the same whether the current or the voltage is increased. If the upper line is extended to higher output power as shown, the indicated processing cost rates for 250, 500 and i000 kW of beam power are $0.00047, $0.00030 and $0°00019/ Mrad-lb, respectively. The validity of the 500 and i000 kW

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figures, of course, is not as good as the 250 kW figure because of the range of this extrapolation and because the design parameters for these larger models are not yet fixed. Nevertheless, this method of projected processing costs from the present power range to the anticipated future range gives approximate figures which are useful for evaluating the feasibility of using electron beam radiation on high-volume processes. SOME APPLICATIONS FOR VERY HIGH-POWER EB GENERATORS There are several large-scale processes where ionizing radiation could be b e n e f i c i a l l y used if the unit costs were low enough to compete with conventional processes and if the thruput rates were high enough to handle the volumes of material involved. Some intriguing possibilities are, (i) the disinfection of municipal waste water by direct electron beam irradiation, (2) the treatment of waste water or drinking water with ozone produced by irradiating oxygen gas, (3) the degradation of cellulose as a first step in the recovery of useful chemicals from municipal trash and (4) the precipitation of sulfur dioxide and nitrogen oxides from combustion gases. Some estimates of EB power requirements and acceptable processing costs for these processes are qiven below. Waste Water Disinfection Ionizing radiation can be used in combination with aeration or oxygen injection to disinfect the secondary effluent (waste water) from a municipal sewage treatment plant (i0, ii). This process is more effective than the conventional treatment with chlorine and avoids the production of toxic, chlorinated organic compounds which are contaminating the public water supplies (12). The radiation dosage required is quite low if sufficient oxygen is present but the material thruput rates and power requirements can be very high in a large metropolitan area. For example, a sewage treatment plant processing i00 million gallons per day (i00 MGD) at an average radiation dosage of 50 kilorads would need 2900 kilowatts of electron beam power, assuming 75~ beam power utilization (13). This would require the installation of 20 of the largest machines in existence today (3.0 ~T-50 mA150 kW) which would probably be too expensive. If this process were designed to utilize three of the projected i000 kW EB generators, the unit processing costs would be about $0.0002/Mrad-lb (from Fig. i0) or $0.083/1000 US gallons. This figure is higher than the present cost of chlorination but competitive with improved treatment processes now under consideration such as ozonation or chlorination followed by carbon filtration (14). Ozone Production Ozone can be produced by exposing oxygen gas to any form of ionizing radiation. Under favorable conditions a G value of l0 (number of molecules formed per i00 electron volts of energy

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absorbed) has been measured with gamma radiation (15,16) o This corresponds to an ozone yield of 0.4 ibs/kW-hr of absorbed power, which is higher than the yield obtained from the conventional electric discharge process (14). For a waste-water disinfection process the ozone dosage should be somewhere between 5 and 15 parts per million by weight, depending on the chemical ozone demand of the water (17). A dosage of I0 PPM would require the production of at least 8340 ibs of ozone per day to supply a i00 MGD sewage treatment plant° Assuming that a G value of i0 is also correct for high-power electron beam radiation, the beam power needed to yield this quantity of ozone would be 1160 kilowatts (for a 75% beam utilization). This would require 8 of the present 150 kW generators. The cost to produce ozone by the electron beam method can be calculated from the processing cost per kilowatt-hour of beam power. For a 150 k W machine at 75% beam utilization this is 50°00064 x 800 x 0.75 = $0.36/kW-hr of beam (using cost data from Table 2). For a i000 k W machine the comparable processing cost would be $0.00019 x 800 x 0.75 = $0.114/kW-hr of beam. Assuming an ozone yield of 0.4 ib/kW-hr, the ozone treatment costs would be $0.36/0.4 = $0.90/ib 03 and $0.114/0.4 = 50.285 ib 03 , respectively. Therefore, the ozonation costs per I000 US gallons of water (at i0 PPM dosage would be $0.90 x 0.0834 = 50.075 and 50.285 x 0.0834 = $0.024 for the 150 kW and i000 kW machines, respectively. These cost figures and the beam power requirement are lower than the values given in the above section, "Waste Water Disinfection". This is due to the lower energy demand in the ozonation process. It is more energy efficient to irradiate oxygen gas and then inject it into the waste w a t e ~ rather than to irradiate the water with oxygen present. On the other hand, ozonation alone may not be sufficient for disinfection because of the presence of contaminated particulate matter. If filtration is also required, then the direct irradiation process which can penetrate the suspended particles, may be cost competitive. Cellulose

De@radatioq

Cellulose, which is a crystalline p o l y m e r of glucose could be a useful feedstock for chemicals and foodstuffs if an economical means could be found to break up its molecular structure. Electron beam bombardment is a pretreatment method which enhances the effectiveness of other chemical agents in the degradation process (18). A huge source of waste cellulose is municipal trash. A typical U.S. city of a million people generates about 1200 tons of trash daily, containing about 700 tons of cellulosic materials (including lignin and water) or about 300 tons of pure cellulose. A radiation process designed to pretreat the cellulosic materials would have to handle about i000 tons of material per day (including chemical reagents) at a dosage of at least i0 megarads. The

High-power electron beam accelerators

e l e c t r o n b e a m p o w e r r e q u i r e m e n t for the above p r o c e s s w o u l d about 1400 k i l o w a t t s or i0 of the p r e s e n t 150 k W models.

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C o n s i d e r i n g the p r o d u c t i o n of g l u c o s e from cellulose, the r a d i a t i o n p r e t r e a t m e n t i n c r e a s e s the y i e l d b y about 1 0 % b a s e d on t h e d r y w e i g h t of t h e p u r e c e l l u l o s e (18). Therefore, the i n c r e a s e d g l u c o s e p r o d u c t i o n w o u l d be about 30 t o n s / d a y or 1.25 t o n s / h r or 1.25 x 2 0 0 0 / 1 4 0 0 = 1.8 i b / k W - h r of b e a m power. The cost of the b e a m e n e r g y from a i000 k W g e n e r a t o r is $0.00019 x 800 x 0.75 = $0.114/kW-hr. Therefore, the cost of the i n c r e a s e d glucose yield w o u l d be $ 0 . 1 1 4 / 1 . 8 = $0.063/Ib. This is c o m p a r a b l e to p r e s e n t cost e s t i m a t e s of $ 0 . 0 5 / i b for p r o d u c i n g sugar from corn starch w h i c h is a c o m m e r c i a l l y viable process. This m e t h o d of e s t i m a t i n g the added value of the r a d i a t i o n p r o c e s s assumes that a c e l l u l o s e r e c o v e r y plant u s i n g the acid h y d r o l y s i s p r o c e s s is in e x i s t e n c e and that the glucose y i e l d can be i n c r e a s e d b y a d d i n g o n l y the r a d i a t i o n p r o c e s s as a pretreatment procedure. Stack

Gas C l e a n i n g

It h a s b e e n d e m o n s t r a t e d that the E B i r r a d i a t i o n of c o m b u s t i o n gases w i l l convert S02 and NO x gases into solid p a r t i c l e s and acid m i s t s w h i c h can be c o l l e c t e d in an e l e c t r o s t a t i c p r e c i p i t a t o r (19,20,21). These r e a c t i o n s m a y p r o v i d e a means of r e m o v i n g these n o x i o u s p o l l u t a n t s from smoke stacks so that h i g h - s u l f u r oil and coal can be b u r n e d in m e t r o p o l i t a n areas. Yhe m a t e r i a l t h r u p u t rates in e l e c t r i c p o w e r p l a n t s are so h i g h that this p r o c e s s p r e s e n t s the g r e a t e s t c h a l l e n g e yet for the e l e c t r o n a c c e l e r a t o r industry. The g a s e o u s effluent from a large, f o s s i l - f u e l e d p o w e r plant r a t e d at i00 m e @ a w a t t s is about 2.8 x 105 cubic feet p e r m i n u t e or about 8 x 10b p o u n d s p e r h o u r (22). At a r a d i a t i o n d o s a g e of 3 megarads, w h i c h can remove all of the N O x and about 70% of the S02, the r e q u i r e d e l e c t r o n b e a m p o w e r w o u l d be about 4 m e g a w a t t s (at 7 5 ~ b e a m u t i l i z a t i o n ) . The ac line p o w e r drawn b y the e l e c t r o n a c c e l e r a t o r s w o u l d be about 8 m e g a w a t t s w h i c h w o u l d c o n s u m e 8% of the output of the e l e c t r i c g e n e r a t i n g plant. The c a p i t a l cost for a i000 k W E B i n s t a l l a t i o n using the g e n e r a t o r shown in Fig. 9, w o u l d p r o b a b l y be about $2.5 m i l l i c n b a s e d on an e x t r a p o l a t i o n of the capital costs given in Tables 1 and 2. Therefore, a r e a s o n a b l e e s t i m a t e for the total c a p i t a l cost of this s t a c k - g a s i r r a d i a t i o n p r o c e s s is about $i0 million. An a l t e r n a t i v e w e t - s c r u b b i n g p r o c e s s u s i n g l i m e s t o n e to n e u t r a l ize the acids w o u l d cost about the same amount (22). However, the e l e c t r i c p o w e r d e m a n d of the w e t - s c r u b b i n g p r o c e s s is o n l y about 5% of the total plant output. If the r a d i a t i c n d o s a g e c o u l d s o m e h o w be r e d u c e d to 2 M r a d s w h i l e still m a i n t a i n i n g a h i g h y i e l d for S02 and N O x removal, this p r o c e s s might b e c o m e a c o m p e t i t i v e m e t h o d of c l e a n i n g c o m b u s t i o n gases. A dry, e l e c t r i c a l p r o c e s s might also h a v e fewer w a s t e d i s p o s a l p r o b l e m s than the wet l i m e s t o n e process.

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CONCLUSIONS There are a number of material treatment processes where electron beam radiation could be beneficially used if the capacity of the EB generators were larger and the processing costs lower than they are today. Both of these conditions can be met by the development of very high-power EB equipment in the 100 to i000 kilowatt range. The existing Dynamitron technology is already reaching into the lower end of this power range with an operational 150 kW electron beam unit and major developments underway which can lead to a 250 kW unit in the near future. Further extensions to 500 kW and i000 kW are technically feasible using the same basic design principles. Multiple beam acceleration systems connected to a common high voltage generator may be needed to keep the radiation intensity within reasonable limits. In light of the favorable prospects for very high-power, very low-cost radiation processes which have been presented here, it might be worthwhile to examine some basic chemical processes as possible candidates for this new technology, especially those that now consume substantial quantities of thermal energy.

REFERENCES (i)

Energy Sciences, Inc., Accelerators, Inc., Emil Haefely & Cie AG, Brown, Boveri & Cie AG, TAM-SAMES, USSR Nuclear Institute - Novosibirsk.

(2)

U.S. Patent Nos.

(3)

Cleland, M.R. and Morganstern, K.H. , "Dynamltron-A HighPower Electron Accelerator", Nucleonics (Aug. 1960).

(4)

Cleland, MoR. and Morganstern, K.H., "A New High-Power Electron Accelerator", IRE T~ansactions on Industrial Electronics, IE-7, No. 2 (1960).

(5)

Cleland, M.R. and Farrell, P., "Dynamitrons of the Future", IEEE Transactions on Nuclear Science, NS-12, No. 3, p. 227 (1965).

(6)

Thompson, C.C. and Cleland, M.R., "Design Equations for Dynamitron Type Power Supplies in the Megavolt Range", IEEE Transactions on Nuclear Science, NS-16, No. 3 (1969).

(7)

Cleland, M.R., "Advantages of the Dynamitron Parallel-Driven Cascade Circuit in Industrial Electron Accelerators", RDI Technical Information Series, TIS 71-9 (1971).

2,875,394,

3,113,256,

3,119,971,

3,244,988.

J

Thompson, C.C., "Advantages of the Dynamitron as an Industrial Accelerator", RDI Technical Information series, TIS 74-16 (1974).

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(8)

557

Cleland, M.R., Hanley, P.R. and Thompson, C.C., "Acceleration of Intense Positive Ion Beams at Megavolt Potentials", IEEE Transactions on Nuclear Science, NS-16, No. 3 (1969). Cleland, M.R., "Recent Developments on the Dynamitron Accelerator", Proceedings of the 3rd Symposium on Structure of Low-Medium Mass Nuclei (held at the univ. of Kansas), p. 230 (1968). Also RDI Technical Information Series, TIS 69-2.

(9)

Amperex Electronic Corp., Hicksville,

N.Y. 1180~.

(10)

Woodbridge, D.D., Mann, L.A. and Garrett, W.R., "Application of Gamma Radiation to Sewage Treatment", Nuclear News, p. 60 (Sept. 1970).

(ll)

Woodbridge, D.D., Cooper, P.C. and Garrett, W.R., "Effect of Gamma Rays on Bacteria and Chemicals in Secondary Effluent", Interim Report for Jan. 72 thru Jan. 74, to Res. & Dev. Ctr., U.S. Army Mobility Ctr., Contract DAAK-02-71-C-0296, "Nuclear Radiation Treatment on Waste Water, (20 June 1994).

(12)

"New Orleans Area Water Supply Study", USEPA, Dallas, Texas (1974), also reported in Chemical Week, p. 18 (Nov. 13, 1974).

(13)

Cleland, M.R., "Methods for Calculating Energy and Current Requirements for Electron Beam Processing", RDI Technical Information Series, TIS 75-17 (1975).

(14)

"Disinfection of Wastewater", 1975).

(15)

Dietz, R., Smith, J. and Pruzansky, J., Bimonthly Progress Rpts., Dept. of Applied Science, Brookhaven Nat]. Lab, Upton, N.Y. 11973 (1969-1972).

(16)

Steinberg, M., Beller, M. and Powell, J.R., "Large Scale Ozone Production in Chemonuclear Reactors for Water Treatment", Proceedinq of the First International Symposium and Exposition on Ozone for Water and Wastewater Treatment, sponsored by the International Ozone Institute, held in Wash. D.C. (Dec.2-5, 1973).

(17)

Rice, R., Washington Representative, Coeditor of Ozonews, a Publication of the International Ozone Institute, Syracuse, N.Y. 13210, private communication.

(18)

Brenner, W., "Radiation Treatment of Solid Waste" Proceedings of the International Meeting on Radiation Processing, sponsored by Am. Nucl. Soc., Am. Chemo Soc., and Soc. of Plastics Eng., held in Puerto Rico (May 9-13, 1976).

(19)

Kawamura, K., Aoki, S., Kawakami, W., Hashimotor, S., and Machi, S., "Treatment of Exhaust Gases by Irradiation", Proceedin~s of a S~m~osium on the Use of High-Level Radiation in Waste Treatment, Sponsored by IAEA, STI/PUB/402, ISBN 92-0060075-1, held in Munich, p. 621 (Mar. 17-21, 1975).

Task Force Report, USEPA

(Jan.

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M.R. Cleland e-~ ~Z.

(20)

Washino, M., Tokunaga, O., Hashimoto, S., Kawakami, W., Machi, S., Kawamura, K. and Aoki, S., "Kinetic Study on the Irradiation of Exhaust Gases", IBID (19), p. 633.

(21)

Machi, S., "Radiation Treatment IBID (18).

(22)

Ruggeri, S., Senior Chem. Eng., Envir. Eng. Div., American Electric Power Service Corp., Canton, Ohio 44701, private communication.

of Combustion

Gases",

High-power electron beam accelerators

TABLE

559

1

P R O C E S S I N G COST A N A L Y S E S INCREASING VOLTAGE-CONSTANT CURRENT PERFORMANCE

RATINGS

Voltage-Beam

Current

0.5MV-100mA

1.0MV-100mA

[.5MV~100mA

100kW-50kW

200kW-100kW

300kW-150kW

.62

.71

.73

Mrad-lbs/hr

25,000

56,000

87,000

Mrad-kg/hr

11,000

25,500

39,500

Line P o w e r - B e a m B e a m Power Thruput

CAPITAL

Power

Utilization

COSTS

(in thousands)

Accelerator Access. Mat.

& Instal.

Handling

Equipm

Contingencies

(10%)

Equipment Facility

Eng.

Capital

Sup.

COSTS

Equip.

Deprec.

525

675

75

i00

125

75

100

125

45

73

93

Totals

495

798

1018

& Const.

100

150

200

595

948

1218

41

67

85

4

6

8

Cost Totals

ANNUAL

300

(8000 hrs) (12 years)

Facility

Deprec.

Interest

(8%)

(25 years)

Maintenance

48

76

97

28

36

44

Oper.

Labor

& Ovhd. ($10/hr)

80

80

80

Elec.

Power

(3C/kW-hr)

24

48

72

23

31

39

248

344

425

Contingencies

(5%)

Annual

Cost

Totals

PROCESSING

COST

RATES

Per Day Per Hour

(365 Days) (8000 Hrs)

($) 680.00

944.00

1164.00

31.00

43.00

53.10

Per M r a d - l b

Product

0.00124

0.00077

0.00061

Per M r a d - k g

Product

0.0028

0.0017

0.0013

560

M~ R. C|eland et al.

TABLE

2

PROCESSING COST ANALYSES CONSTANT VOLTAGE-INCREASING CURRENT PERFORMANCE

RATINGS

Voltage-Beam

Current

Line P o w e r - B e a m Beam Power Thruput

CAPITAL

Power

3.0MV-25mA

3.0MV-50mA

3.0MV-100mA

150kW-75kW

300kW-150kW

600kW-300kW

0.75

0.75

0.75

Utilization

Mrad-lbs/hr

45,000

90,000

180,000

Mrad-kg/hr

20,000

40,000

80,000

COSTS

(in thousands]

Accelerator Access. Mat.

& Install.

Handling

Equip.

Contingencies Equip. Facility

Sup.

Capital ANNUAL

COSTS

Equip.

Deprec.

Totals

950

125

150

i00

125

150

85

i00

125

ii00

1375

250

3O0

350

1185

1400

1725

78

92

115

i0

12

14

95

112

138

40

48

64

& Const.

Cost

750

i00

935

(10%)

Totals Eng.

650

(8000 hrs.) (12 yrs.)

Fac~ity

Deprec.

Interest

(8%)

( 25 yrs)

Maintenance Oper.

Labor

& Ovhd(Sl0/hr}

80

80

80

Elec.

Power

(3C/kW-hr)

36

72

144

34

42

56

373

458

611

1025.00

1255.00

1675.00

46.60

57.20

76.50

Contingencies Annual

Cost

PROCESSING Per Day Per H o u r

(5%)

COST

Totals RATES

(365 days) (8000 hrs)

($)

Per M r a d - l b

Product

0.00104

0.00064

0.00042

Per M r a d - k g

Product

0.0023

0.0014

0.00095

High-power

electron b e a m accelerators

Fig.

1

A 4.0 MV Dynamitron with Vacuum Tubes

Cascaded Rectifler

Fig.

2

A 3.0 MV-50 mA-150 kW Dynamitron Solid-State Rectifier Modules

561

System

System with

562

M.

Fig.

R.

Cleland

~'~ T h o R , ~ c t l f J e r U o J u m n k W b%nlalT,~t ro~'

~ t u

cf

.

a

] .0 M V - I O 0

mA-i','{}

High-power

0

240

electron

beam

563

accelerators

20

40

60

80

IO0

120

140

I

I

I

I

I

I

I

160

220 -

200-

180-

160

80

140,

-70

EFFICIENCY i

120-

-60

o

IO0 -

-50

BO-

-40

I >0 Z hl

60-

"50

0 h I.l.. W

40-

-20

n," l,iJ

U.l Z ._I

20 L

FIG 4

qO

M O D E L IEA 3 0 0 0 - 5 0 - - 4

130 OOKV-50 MA-150 K W

0 0

I

I

I

I

I

I

I

20

40

60

80

I00

120

14.0

BEAM POWER- K W

0 160

564

M. R. Cleland

F±g.

H~,]I~ F r e q u e n < y ]:'OW~: :

~:'~,<~,'.

Generator

Rated

for

High-power electron beam accelerators

//

~-HIGH VOLTAGE GENERATOR

/ l-

I

---ACCELERATION TUBE

/ HIGH ~0LTAGE

CONNECTOR

/

565

ELECTRON

/

/-GUN

w

SCAN MAGNET

VACUUM PUMP

wl NDOW COOLING MANIFOLD

ELECTRON BEAM

2-5 MV-4OO-MA

FIG 6

'

'

'

I

DYNAMITRON '

' ' ' 1

'

'

ACCELERATOR '

'

I

'

LINE A, 3.OMV- INCREASING CURRENT-25-50-IOOMA "5000

LINE B, IOO MA- INCREASING VOLTAGE-O5-10-1 5 MV

i z 3 o o

FIG 7 CAPITAL COSTS VS. ELECTRON BEAM POWER

I

I0

I

I

I

I

I

I I I

I

i

I

I

I00 P-ELECTRON BEAM POWER IN KILOWATTS

|

I

I

I

I

I000

56b

M.R.

C[eland

,~/

,JZ.

.010 f LINE A, C=0.0165P "0.642 3.OMV-INCREASING CURRENT- 25-50-IOOMA..1

.oo,t W

.

W 0.

.

LINE B, C=0.0154P-0"642 T IOOMA-INCREASINGVOLTAGE-0.5,1.O,I5 MV .~

Z

0 U Z

"' .001"

"

U

0 0.

6 .0005"

FIG.8 PROCESSING COST RATES VS. ELECTRON BEAM POWER

.oool-'rio

I00

200

300

P-ELECTRON BEAM POWERIN KILOWATTS

500

I000