121st NATIONAL ACS MEETING—MILWAUKEE DIVISION O F INDUSTRIAL AND ENGINEERING CHEMISTRY
Technology of Radiochemical Plants Differs Little from Ordinary Facilities • Control of overhead cost a n d versatility of prime importance in multiple-use plant HE chemical technology of atomic energy installations is similar to and in many instances no more difficult or hazardous than that of ordinary industrial units. Security-cleared papers presented before the Symposium on Radiochemistry seemed to bear out this statement. In spite of this similarity there is a number of important problems which are peculiar to the technology of radiochemical plants. F. L. Steahly and W. K. Eister of the Oak Ridge National Laboratory listed these problems as follows: ( 1 ) the quantitative removal of fissionable material; (2) the quantitative removal of radioisotopes from fissionable and source material; (3) the question of critical mass; and ( 4 ) biological hazards. The removal of fissionable material must be with a yield in excess of 99.9% because of cost considerations, Steahly said. The removal of the radioisotopes is important from a health hazard standpoint. The importance of not exceeding the critical mass is obvious to anyone who understands the first principles of the atomic bomb, Steahly commented. Critical Mass. Critical conditions result from the accumulation of a sufficient mass of fissionable material in a geometric configuration which minimizes loss of neutrons produced by the spontaneous fission of the fissile element adequately to allow a chain reaction to progress, said Floyd L. Culler, also of the Oak Ridge Laboratory. Solutions containing U233 or Pu239 can be made to, or can by accident, go critical during chemical processing, he said. The system must be so designed that the mass of fissionable material allowed in any batch tank can be controlled, or the geometry of the tank must be such that the neutron leakage is high. Culler indicated that continuous processing equipment can more easily be designed for high neutron leakage than can batch units. However, radiochemical plants are using batch processing almost throughout for maximum control and simplicity. "The concept of batch processing as practiced to provide safe and simple processing techniques is probably the greatest single factor affecting the cost of radiochemical plants," said Culler. He commented briefly on shielding. Biological shields are designed to provide for a maximum irradiation of 6.5 milliroentgens per hour at the surface of the shield (biological tolerance), and usually are designed for 0.1 tolerance to provide 1516
an adequate safety factor, Culler said. Shields represent approximately 15% of the cost of a completely equipped processing building according to Culler. "At the present state of radiochemical technology, more monetary savings can be realized b y the development and proving of new philosophies of design than can be obtained through the utilization of new chemical processes," Culler concluded. Radiation Initiated Chemical Reactions. The pros and cons of using radiation to initiate chemical reactions were included in a discussion of the industrial utilization of fission products by Bernard Manowitz of Brookhaven National Laboratory. Chief disadvantage seems to be the high energy input required to effect chemical reactions on a commercial scale. Many millions of curies would be required to produce simple decomposition products on a tonnage per day basis, he indicated. On the other side of the ledger there are numerous advantages to this approach. Reactions can be initiated at low temperatures. This would be particularly important in. systems of high thermodynamic yield at low temperatures and where the products are heat-sensitive. Theoretically it may be possible to produce free radicals at temperatures low enough that the recombination of the free radicals is inhibited, transport the free radicals in the frozen state, then use them to initiate a reaction, he said. Other advantages of radiation initiation listed by Manowitz were: the possibility of controlled initiation rates; the elimination of chemical additives in the reaction mass; initiation external to the reaction vessel. Radiation initiated polymerization has been studied at Brookhaven. Manowitz reported that three million roentgen equivalent physical ( R E P ) were required to polymerize methyl rnethacrylate, three million REP to polymerize vinyl acetate, and 35 million REP to polymerize styrene. Because of t l 3se high requirements radiation cannot compete with the standard methods of polymerization, he said. Manowitz referred to the efforts toward fission product utilization as embryonic. Ground work: in fission production sources will take at least two years, development work another two years. It will take five years more before cheap megacurie sources of long lived fission products are available, he said. liowever, experimental CHEMICAL
sources of cobalt and tantalum are available in 1000-curie lots today, he pointed out. Tracers in Pipelines. Radioactive isotopes have been used to follow the interface in common carrier pipelines. D. E. Hull and J. W . Kent, California Research Corp., told how barium 140 and antimony 124 have been injected in pipelines to give much better results than previously obtained by the conventional gravimetric or colorimetric techniques. Oil-soluble isotopes are injected in the line at the time a product changeover is made. Geiger counters mounted on the pipeline at various points enable the operators to follow the flow of products and to judge the amount of intermixing. Containers of the isotopes are shielded and after injection the radiation hazard to operating personnel is nil, Hull said. ^ M u l t î u s e Plant Requirements The importance of cost considerations and provisions for versatility were emphasized during the Symposium on the Multiple Use Plant. Chairman of the symposium was F. J. Messman of Win S. Merrell Co. Overhead cost can make or break a company, said L. W. Garner, J. T. Baker Chemical. He referred to his own company as one of the best examples of a multiple use plant in the chemical industry and used it as a case study. He explained a numerical cost distribution system which was used. The data are transferred to IBM punched cards for summary and distribution. The use of the IBM system has allowed the cost accountants to spend much more time in actual cost analysis, Garner said. In the distribution of overhead costs it was found that direct labor was the best common denominator to use. He mentioned that the overhead ratios have been increased four times since the start of the Korean war. By-products can be credited at full value against cost of principle products or treated as separate products themselves. The significance of the volume of production is the deciding factor, he said. All costs cannot be allocated directly to individual products when several are being produced simultaneously. This causes some concern among production people but Garner indicated that the prorating method was the most workable approach. A method for allocating overhead expenses in a multipurpose plant using both labor and equipment cost was explained by W. S. Guthmann and P. R. Inman, Edwal Laboratories. Overhead costs related to and allocated on the basis of labor cost include supervision, vacations and employee benefits, payroll taxes and insurance, factory supplies, control laboratory, and shipping and receiving. Overhead costs related to and allocated on this basis of value of equipment include, depreciation, insurance, reAND
ENGINEERING
NEWS
MEDICINAL pairs and m a i n t e n a n c e , h e a t light a n d p o w e r , a n d p r o p e r t y taxes. G u t h m a n n exp l a i n e d t h a t o n t h e basis of t h a t division t h e y calculate one o v e r h e a d factor w h i c h c a n b e a p p l i e d to labor a n d one which c a n b e a p p l i e d to e q u i p m e n t . "This d u a l application of o v e r h e a d r e flects a satisfactory estimate of cost, maki n g allowance for processes w h i c h are comp l e t e l y different in size, difficulty a n d e q u i p m e n t , " h e said. Dual E q u i p m e n t in M e d i c i n a l Plant. All major reaction vessels in t h e multipleuse plant described by E . J. Nolan, Merck & Co., Inc., a r e d u p l i c a t e d in b o t h glasslined and stainless steel construction. This allows for t h e utmost in versatility of operation. T h e Merck plant w a s d e s i g n e d as a p r o d u c t i o n unit i n t e r m e d i a t e between pilot plant a n d full scale. P r o d u c t s are m a d e in t h e multiple-use p l a n t while undergoing clinical and m a r k e t evaluation.
H a z a r d o u s reactions are carried out in a s e p a r a t e building w h e r e e v e r y provision is m a d e for safe operation. NIolan described the sodium reaction b u i l d i n g a n d t h e hydrogénation and Grignard reaction building. H e indicated that separate units were planned for the nitrating a n d c y a n i d e operations. P l a n t For C a t a l y s t s . A multiple-use plant for manufacturing catalysts w a s described by P . L. V e l t m a n a n d A. W . Hemphill, Davison C h e m i c a l . A typical flow diagram applicable t o a b o u t 6 0 % of t h e products was set up a n d the e q u i p m e n t laid out on that basis, Hemphill said. Of particular interest in t h e n e w design are the transferable b a l c o n y sections. Sockets are placed in t h e floor at 10 foot intervals and b y removing a few braces the balconies c a n b e m o v e d into any d e sired position. Provisions are also m a d e for placing one balcony on top of another to give a third operating level.
DIVISION OF MEDICINAL CHEMISTRY
IMew Drug Shows Promise For Petit JVIoS Epilepsy ^ Antimalarial activity discovered compound, revealed as metabolite antagonist
in
simple
k Sequestering agent effects dramatic recovin cases of l e a d poisoning enes A NEW drug that is relatively nontoxic a n d shows promise for clinical use in the t r e a t m e n t of petit m a l epilepsy w a s announced "by Loren M. L o n g of P a r k e Davis. Called Milontin, the c o m p o u n d is Nm e t h y l - a - p h e n y l s u c c i n i m i d e . I t has been studied over the past t w o years in 65 cases in -which it gave 5 6 % reduction of seizures, complete control in 3 0 % of the cases. T h e corresponding N-allyl derivative, which has b e e n s t u d i e d in 14 cases, g a v e 66c/ more animals developed diabetes; all of the r e m a i n i n g five lived. Local A n e s t h e t i c s . A series of amino> esters of various chlorine-substituted benzoic a n d cinnamic acids that were prepared in a search for local anesthetics showed more promise as cardiac drugs, according to E . L. S c h u m a n n of W m . S. Merrill Co. A m o n g these products, the diethyllaminoethyl esters of 4-, 2,4-, a n d 3,4-dichlorobenzoic acid were considerably less toxic than procaine and h a v e about equal duration of action. T h e 2 , 5 - a n d 2,6-dichlorobenzoates w e r e more toxic, a n d 2,6-dichloroester w a s the least active. Among the cinnamic esters, which are vinylogs of the b e n z o a t e s , t h r e e h a d a duration of action equal t o procaine, and t h e 4-chloro derivative w a s least toxic.
L o r e n M . L o n g of P a r k e , !Davis & C o . described t h e structure, synthesis, a n d action of Milontin, a n e w antiepileptic d r u g , at the symposium o n anticonvulsants o n Monday
APRIL
14,
1952
1517
