NOTICE: “BEST AVAILABLE COPY” PORTIONS OF THE FOLLOWING DOCUMENT ARE ILLEGIBLE The Administrative Record Staff S REPORT IS REPRODUCED ON LIGHT AND HEAT SENSITIVE PAPER I I I I D 8 Im 8 I I I 8 I I I I 1 I I A report prepared for the Deputment of Energy / Rocky Flats Office and managed by the Los Alam Technology Office Rocky Rats Plant Golden, Colorado PYROPHORIC POTENTIAL OF FINELY DIVIDED PLUTONIUM METAL IN SOIL AT THE 903 DRUM STORAGE SITE, PLANT, ROCKY FLATS GOLDEN, COLORADO David L Clark and Nuclear Chemistry Division haAL.mos National Laboratory June 1991 Table of Contents Executive Summary .................................................. Pnmary Factors...................................................... Additional Mitigating Factors....... .................... Conclusions.............................................................. 1.0 Introduction ................................................... 2.0 Terminology .............................................................. DNm 3.0 Hidtory of Rocky Flab Piants 903 Storage Site. - 3.1 Uw of 903 Drum !%rage Site ................................... ... 3 3.2 I#t.cn................................................................. .... 3 3.3 capping d 903 Site>,I............. .............................. ...... .4 3.4 soil chvrteriutior\. ................................................ .... 4 4.0 Factors Affedng the Fymphoricity of Plutonium ............. .............3 4.1 AutoigniW and Watjop\ B&avior ................................................. 6 42 Partick s& d Activity ...................................................................... 7 4.3 Effect d Mo&ture".-""........" .......*....................................................... ..9 4.4 EfieddHjTdrQp..-........*........... * .......................................................... 9 4.5 Purity, Cotn- and Cmamtration of Plutonium in Soils. 13 4.6 Amormt of Rotmsve Stdace Oxide ................. .... ...i .1 4.7 i(inetic and Thermodynamic Considerations .............. 6- 5.0 GmdwioruDNm on tho Pyrophoric Potentul of Plutozuum Metal .- at th Xk3 Storage Site ................... .- 6.0 Achowkdgments............................................... ............. .- 7.0 Glossary ..................................................................................... .. 13 7.1 pyrophau, and Pyrophoric......................................... 19 7.2 I@tion, Piloted Ignrtion, and Autoignition .......................... 19 73 IpWa Thmparture ..................................................................... 19 7.4 and Spontaneous Combustion ............................... :3 8.0 m....."................................................................................................. 2'3 11 1 - 1 The Department of Energy’s DOE’S Rodcy Flats Plant, near Denver < o.( rldt,, ! is cunently addressing the question of plutonium pyrophoricity in regard +u environmental restoration activities at the 903 hrnStorage Site Plutonium I metal has been hwnto ignite spontaneously, and the possibility of A ylutor,iirn fire is a concern. 1 In the eariy 196(k, oils containing p~utoniumleaked from dru s*ored a! !?‘..e I 903 Drum Storage Site; the estimated release was about 5,000 gal. The distnboQonut U plutonium in soil under the 9a3 Pad is lrhmpmms, making it difficult to estimate exact cuncuttratiam A study performed a few yean after the site was I from capped in 1969 found both rsopU (in cancentrations ranging 427 pCi / g to rOA5 I pCi/g) and (in -tias ranging from 282 pCi / g to 2,273 p~i/R, m the soli beneotfi the cap. 1 Thb repat examhe8 the pyrophoric potential of finely divided plutonium at the 903 Site by Surmnuiring literature data ud Uuiynng the probabdiry and ertmr 1 pyrgrhanc to which plutmium is in its present state in the 903 Site sod. I P-F1ctob* I CJculrdoCu show that putidcr of &st- plutoruum have a cntd ptiderfirrd-y Smthat is, only partrdes smaller than this sue I wo\Jd karpebd to rtwm pymptumc betuvior on exposure to air. Oils were sreved befoa I phdin thc dnrmr, SO plutonium partides that entered the wtl were no more than 100 pm in dhneter. Dilution of these particles with large amount3 of soil duces rheir wrophoriaty because heat produced in oxidation processes is absorbed by the surrounding rmtenal. Additionally, oxidation of plutonium by gueous rlpntr much as oxygen or water vapor generates an adherent 111 oxide film on the surface of the plutonium particles. TIUSoxide surface furt.Ser reduces the potential of pyrophoriaty. Thus, the combinanon ot :actors-the requirement for a very small particle, the presence of the protective oxide 5u1:4tce, and the dilution of putides in soil-should render the plutonium :n the %?7 Pad soil highly inert with respect to pyrophoriaty. Additional Midgating F#ton During the in- g years, however, other mecharusms have further rduaed the podbibility ad pyrophoricity of plutonium m the wnb. It is probable that reactions between the plutonium and aqueous groundwater mixtures of chlonnated solvents known to be pmnt in the sail beme& the 903 Pad have rendered the plutcmium IYWI-PyrDPhOCK* UndCI thc canditioru presented. The plutcmlum oxidatjosh Idn+tia showr that dw &time d a 1- plutomum particle LS only 8 4 days in liquui water, utd 4 minutes in a carbon tetrachloridemethmd muture Gmdusimw It is conducted from th discusions and data presented that the plutoruum :n is is them Pad sdl inert with nqr+ct to pymphmaty. This amdusron supported by the fad that IY) pyrophiaty was found during the November 1968 remedlai action at the RX3 Ikrnn Sbqe Site, which involved suaping plutonium- am- ad Irmrlh area The reactions ot plutonium meul or oxlde - in plrrsa wltb thr wyanmsive organic mixtures the soil under the 903 Pad* are stpcrd to k lwtmdt0111and complex. Thus, without exact data on the form chemical and speciation of plutonium under these conditions, it is impossible to predict with absolute accuracy the ultimate fate and transport of plutonium con taminants in the 903 sic mil. Prophoric Pottntid of Finely Divided Plutonium Metal Soil at the 903 Drum Storage Site h * at Rocky Flab Plant, Golden, Colorado BY David L Clark TkDOE'S R0dE)r Flats Plant, near Denver, Cobrado, 19 addresing the quesa d pbWm -ty at the 903 Dnun Storage Site Because plutonirw mctJ hr betn known to ignite spontaneouslv, concern about the appclpriate.1-i Ihe pyroptmidty o€plutonium u possb&ty of a plumurn fire LS a prMr, Seriour mtba kame d worker, and envirmtal health and safe T?tb irrurCb time!ly-the DOE b pluvungremodial activlty at the 905 DNm WhM Strmge Site, has kcn contaminated with plutonium 5 From October 1958 to January 1%7, drums ccmtlining waste macRine cutturg oil that was radbctidy amtarnhtd were stoted at the 903 Site.', As a result d leakage of about 5,OWgl. ot wdf that occuned from dnuns while they were stored at the rgpppdnudl %ita 86 8 (5.3 Q) of plutonium was released into soils st the 903 Drum Sqdirr'3 rrphrk kr OOMahwnt pad was applied at the site in oaober 1969. Several years after the asphalt amer was applied, a study of the soil beneath the 903 Pad indicated that the soil wucontaminated with both plutonium and amenaum is The purpcme od this report to examine the pyrophoric potential of finels divided plutonium at the 903 Site. The report sumarlzes literature td:a on !dC:\C. influencing pyrophoriaty and, using this information, analyzes the grobaoLrts drd extent to which plutonium is pyrophoric in the sol1 at the 903 Drum %rage 5;~ 'Ibc fdhfhg informrtim, which was drawn from historical records, aerd p-phy, ud in&n&w~with plant personnel, is an abridged version of data presented in the FdPhase II RCRA Fadlity InvestigationlFeasbdity Study Work pim.5 From ocdober 1958 to January 1967, the 903 Site was used to tore drum\ contiuning waste machine cutting oil that was radioactively contaminated 3 Litg3t (it the drums were 55 gal. in size, but some 3O-g;l.l. drums were also present, and not a.i of the drums were full.6 About 75% of the drums at the storage site were contaminated with plutonium; the maprity of the remaining drums contained ur ani urn. Mort ot tk plutdrncontaining dnuru held wate lathe coolant consistirg d a high-moleculu-waght, straight-bin hydrocarbon oil (Shell Vitrea) and carbon retrrChbriQindiVaWppXWXU. Other site drums contarned lrqwd waste, such as hydraulic oils, vicuum pump oils, trichlorosthyiene, tetrachloroethylene, silicon db, acetsme, still bottom, e&. The drum ammts were ongutally Lndiated on dwoutridc, but -and lac% of other supporhng records has made detaikdidcntiAatbrrdiffieJt Shipmattddrums bo them Sile ended in January 1%7, when dnun removaldsolrtrl#gh 6yJunc1%8,alldntmrhdkcnranoved. Fneberg desuhs moreeutensivdy the chrondogy of the 903 Site deanup' w 32 -IUlu(lrddffr0ar *drums was first noted edy during the site's use, and UtLA in 1999,ahdambuwaa to the oil to reduce the conosicm rate of the steel drum& Durbrg huuiling routllu &tnn operations in 1964, drum leakage was again noted 8t the 933 SIe. The umtmts of leaking drums were transferred to new drums, and the artire u11 wufenced to restrict access.8 Infonruticm provided by individuals nho WLII involved in site operations indicates that about 420 drums leaked b mme of these, rpproximrtely 50 leaked their entire contents 8 It IS 3 I I estimated dut 5,000 gal. of waste oil leaked from drums onto the ground at the 903 Site. Biwd on oil samples taken from drums, the average plutonium concentratinn 1 x CI) was 4.54 10-3 g/L (280 pCi/L). Thus, approumately 86 g (5 3 of plutonium &'a5 I released into