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Operational Officer plan the same. Donald H. Cardiaer, Director Health and Safety Division William A. Brobat, Sadiological Phyoiciot BEST COPY AVAILABLE Dave anith and I attended 8 meeting a t Oak Ridge FJntional Laboratory on March 11-12, 1959, 09 the do sie try of radiation accident.. general, the pofnts covered -re the dosimetry problem in the Y-12 and IASL critical it y accident8, new methods of nutnitorlug such accident8, phySiCa1 analyses of accidents, aad general philoaophiea i n health physics coverage of accidents. Allin all, it was one of the more ~ nter cet la gm xth gsI have yet attended, 0 8 there was plenty of opportunity for side discussions (the heated type) m d diugrecrecnt. I think Dave and I both dimgreed w l t h most of the basic conclusions of the meeting (re philosophy), and i t is interesting t o note tbt we were not alms. Of the 85 o r am persons attendiug, I bel fer IC reasonable t o aesume that about half came away WLth P 180° change in thinking from what they had before the meeting.
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f'W.'ACY ACT MATERIAL REMOVED (because of the prolonged oscillation of the accident), they used an effective y/in of 2.8 t o determine the close. blood urreples by placiug them in a 4 Ounce polyethylene bottle 00. photo = ul tip llar tube, with a disc rh tor setting at 2Wev. the re8ulta '&thin 20% with thie method. They counted their 1.67 x 1t4 rcdjuc/cc of blood. They feel that they can reproduce Payne Harri o, LA%, theu described the osi retry of their acc ibn t. Like Y-12, they figured about 1.3 x 10" total fissions (+lox), with the neutron exposure taking p l a c e within 200 microseconds. Prom the sodium counting, they nea8ured about 300 d cro curl cs of uniformity of the dose to , they figured the average neutron dose t o around 8150 rad, rfth good correlation between the coq ut ation a Iraa whole-body and blood counting. got about 3 rad. A l l this uaa baecd, of course, on 1 . 5 gram & k i l o of body They r1.o figcrire that about 252 of the total dose cam be measured weight (or 3.2 1ps/ca3), which ie pretty standard from man t o man. -8 by sulfur buttons, which unfortunately d i d not have in measuring the East ueutron dose only. For , they uaad a gaxuaa/nQutron ratio (for the upper portion of the body) of about 3:1, as thc rcm a little moderatton in this direction by the solution. For the lover body, howver, i t increased to about 1 O : lIQ lt to the increaoed de ration. As a baals of COQparlson, they fn ratio. for bare metal aystem could run as lato a a I suppone this i r the point to mantion that in neither of the rcci - denta were any of the peroons Fnvolved vearing peraonuel DPonitorlag devices, nor were any special doae measuring device. I n t h e areal Sxin Eurst, WIL, then described hfs dosimeter and proposed method of uoing it. Basically, It consists of the following: 1. Two gold foils, one covered vlth cadmium, for dctermiaing the t h e m 1 f1.ux (the difference in Au activcatfon). PRIVACY ACT MATERIAL REMOVED
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foil, all three contained within a Boron-10 shell, lor determining the flux abave 1 kev, 0175 W v , and 1.5 Hev, respectively. 3. A Sulfur-32 pellet which aeasureo tha amatran flux above 2.5 (We wre presented w i t h 8 large sheaf of paper6 describing the system and how to use it,) dosimeter for deterrpinatian of the guar doar. runs about $500 each. Tha whole package Rurrt dtacrlbcd the ideal monitoring system for critical it y accidents. 1. Agam - i a sensitive neutron measure. 3. Soow nethod of indicating the! dfrcctlan from which the dose was received, relative to the position of the body. 4. A quick soanning method for dctetminfag critical radiation casea. He then pre8cated u beautiful fornarla which I want t o get down before I forget it. neutron do8e i n rad using the Eiurst dosimeter: It ia the baric forwrla for deternining the 1'11 not bother to cxplatn the terw, other tbaa I, which is tho neutron flux. The fOlllar18, Its use and vagarTIcis, are all rather fully explained ina pamphlet wbich I have.
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Donald H. Gardlner April 9 , 1999 Sam Slgoloff from E W (Nevada Test Site) told of h i s chemical available ca6mmerciall7 from EGW, by the vay. Its prfncipla of operation l atl ht g(lpg radiation dll relutst hydrogen iona from the hydtocarbma, which vi11 then act to change the color of the expbnsivt - rbart $40 per unit of 7 do8imetera. tal at lv ely lnmsaritive to fast nevttaps, but dl1 react to slow neutraau. Don O t t from IASL worked with Saa on this, a d presented alf ttl u -re fnfomstion on the details o f the 2-phare chamical pboe type, The l-ph~mi type I6 oem tt iv t to both 8- and the full speetrrrol of necutrons. wll, and he pretty aauch skipped over I t . Tbc n.plmse of the dye is soarevhat linear, rather than It looked l i k e s nice Little package and mot too,' She half-phase didn't seem to be workfag out dosimeters, which appeared qufte novel but praai8ing. He use8 a little tiny (1 c a long, 1 rod which w i l l react to gauana radiatioa (and slat neutrms) by 8 chemlcal reaction. The incrrascd phosphoreaenct can be memmred with an electronic reader t o determine the radiation dort vithln lU% o r better (ctdmed dom to 3%). c-rcirlly from Bausch and toldb, for $44/c, or 44c each. reader c o s t s $2000, but this cost problem could probably be solved of the reme do abet tr (DT-60), and aentiollcd poor qualttp control, with about 2oX being unusable, but the other 802 good. Be ratamred accuracieo i n the range of 52. The rod8 are p o w available Paync Earris described the dl it ary type Frank A, Davis talked a little further oa Bitchit's blood counting technique, but didn't present anything nev - just explained more Mxic Cal1lhaa gave a d@6Crlpti011of the 9-12 accident, pretty much a s covered in the report Y-1234. 000 additioPs1 fact -2.1 kg of full7 earfched uranium, in 56.2 liters of ~ l u f l o n , in 8 55 galloa drum, at the point of initial criticality. The dov addition of water kept the system critical for about 2 0 minutes until the uranium concentration became low enoght t o ehut itself off. Hugh Paxton g a m a description of the IASL accident, which differed i n detail conriderably from Pup @ Earria' talk the previous day, but uua interelsting none the l e e r . 116. brought out that people bad
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t o be especially careful in epecial operations and Inventories. "Beware of 8 maze of pipes and tahks, watch for areas of possible breakdown of administrattve control, md critic aLl ty accidents w i l l again become rare." Note: The IASL accident happened betveea Chrirtaaa, und Hew Year, wtaea am overly-euergetic clpployee tried to do tolo much a t once, to &cmpletc the inventory. canblacd several 8teps vhich 8 h l d bave been done .itp.ratelT, and heuce the accident, J, XI, XcLendoor, of Y-12, told US all rboat health p h p i c 8 problem, but his talk cmrt of fell flat.I guess he thought that there =re no health phyriicirts in the wdlencc1 E, D, Gupton told us a l l about the new ORlYL film badge, W c h will contain an indiuar foil, uulphur pellet,glass rod dosiwter and gold foil., This wrapped up the wet lng, vhich ia itself vas vary interesting verc the side discussions. You m y recall ue asked our co~ltr8ctof8 (before the nweting) how many dosineters they wanted. W e asked 8oae of thrm after the aeeting, and t h e y were maddenly hit With budget restrictions and other limitations, because thy wanted to dras tlc ally reduce the original number. our discussloins fn the hallwiy. What &de the entire tripa success, houcver, We had expectad this from going a r m d eas, Who needs it?" (quote Dave). Beard's position wcta that thelknuul Chapter 0523 stated that the dose shall be determined by the best method available, and he coasi8ercd that thio doeimeter was the best method available for critical it y accidents, While Dave and I agree with that .tatereat, w e di8ugree, rather firmly, with tht philosophy of the beat poesible ick and Dirty Nethod of de raining the degree of oversure. The 51-8 tcu doern't really have it. The gold o 8 tlatck, 3/8" w t c r ) vi11 not be hot enough fair G I 4 portable instrument detection until the lethal dose hao been exceeded many times. Saae for sulfur, Tbe fission foils won't give e quick indicatlm. There is w Indium fad1 for o c ~ Ip8 ,as this is pnaumed baing worn on 2 . Accuracy. With the Burst dostmeter (if you have enough of theo! spaced no more than 20 feet apart, Sa the right area)
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PRIVACY ACT MATERIAL REMOVED you can caw with ln S - l n of the total oeutron dose. You still have to calculate the dose. With no dosimeters a t all, I ASL calculated the dose t o within 3a, and Y - 12calculated the dose t o their vorkers within 3%. With you could conceivably come within 10-lS%. only 1011. at the most b y the Eurst dosimeter. So pau cart geln 3. Equipment K. The Burst dosimeters coat about $500 each. For a mall facility (such as AML), about 40 such doslmetcre would be required, at a cost of $20,000. So, for a total cost of about $30,000, you can determine the dose 1oZ more putting tb tat $30,000 into additional safeguards to prevent critical it y fropl happening? It wwld take about 6 dosimeters, o r $3,000. That's mre thun they bava in their total health physics equipment inventory now: I don't think they can afford to buy all this htghIs it worth i t ? Or would you be better off 4 . Expense oE Dose Determination Without t h e System. Proponents of the Eiu-cat dosimeter claim t h a t the expense of determiaiag the dose ins closely as possible d th out the dosimeter would more tban pay fora dosimeter metrp-. Thin le probably true. But every place Is not going to have a crit l cali ty accident, and I think that the total cost of the CocPraiasion of a full brat dosimeter setup would far exceed the cost o f doing what LASL and OBM. did to de ted ne their doses, even a t the rate of two accident' a year throughout the Ccna!nisriFon. So the Mes Lon as a &ole \Iourd ou ffe r an unnecessary 42xpetHSC. The aforementioned proponenta elm stat; that the mll coamw-clal facilities wouldn't be able to afford a lengthy lavertigation llke IASI. and OWL had to do. This also la tme, but i f D. E. Mukepeace! had a critical it y accident, and 8- people were exposed, they would have to lock the doors to keep OH&, IASL, Copa is sL on contractors smuld be begging t o come in and do the aaalysfe fret j u s t to get tbe Information. So uhy should the small outfits have t o worry about the expense? They wouldn't umch difference just what he got ; he's dead, and his mundvorr will be compenasted equally uhether be got 900 or 90,000 r. True, L t would be nice to knou the exact d o ~ e , to get some more correlation on human reaction t o radiation, and to add a little more human data t o the fogged field, but industry If a man receives a fatal dose, it doesn't make
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is out t o make ploney, not to worry about human data for some research doctor samewhere outside of h i s organization. If the maxn receives a dose less tban 200 r , 2oX one way or the other really won't have bo rrch slgpfficance. t o 32 when hie response may vary It is bhly in the critical taw between 200 r and 600 r vhere Burr it do a hett r would give information which could be used to determine the applicability oi treatment. For this limited use, the &rat dosimeter costs a pretty penny. I propose the Brobst doalmeter, vice the &rst doalmeter, for the majority of situations. dosimeter, leris the fismfon foil-boron b a l l , and pluo an indium This dooimeter uould consiat of the &rst Indium fojg - for qulck determiPation of dose. Size: 10 dl8 thick, 1 11/4" long, 1;~" vide. Camma response: 1 mrhr on a G-H counter per 800 wad of neutrons. Accurate t o withie Thir foil vould also be worn on the man's security Gold f o i b 2 ) - for thermal neutron measurement. One foil is covered with cadmium. Foil size : 5 mils thick, 3/8" diameter. The bare foil w l ll respond to a fairly c-letc spectrtim (by measuring the bare f o i l ) . A check on the faat flux can lbe -de by measuring the cadmium covered foil and comparing it with the flux as measured by the Sulfur bus - for de ted nrt ion of the fast flux, with a threshold actiwtion energy of &.!iKev. Size: 3/8" thick, Chemically pure Sulfur, weight about Set of Faur Glaos Rod Dosimeters - for determination of the me slow neutron dose can be subtracted oat (ueing data from the gold f o i l ) and the gamma dose calculated. The Brobst dostmeter w i l l give good information on (raanna dose ( v f t h i n 5%). md good information on the high and lov endo of the neutron apectruea (within 10%). It will give a very rough idea of the t o t a l neutron spectrum (within 50%). However, QUY nuclear physicist worth his salt can calculate the approxiaatc ganrma/ neutron ratio (given the details of the accident) and from the type of accideat can predict, quite accurately, the shape of the
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PRIVACY ACT MATERIAL REMOVED neutron spectrum curve. curve, and come idea of the rciddle, the total neutron s p w t m c m be calculated to within 15%. All of this will then lead to a gampo dosc calculation a thin 5X and a neutron dom (rad) calculation of from 10-152. For the vast majority of instances, t h i s , …