92020B3.MPB Chapter 2. Uranium Releasesto the Environment .. Operationsat SRS involve theuse of uraniumin both researchand productionareas. The isotopic compositionmay varybecauseuraniumthat hasbeen eitherenrichedor depletedin the_sU-isotope andnaturaluranium, which is nativeto the soil andwaterof the SRS, are presentoa the site. Uraniumon the site is presentin manychemical forms,such as the metallicuranium anduranium-aluminumalloy in fuel andtargetassemblies, varioussalts, such as uranylnitrateor uranylsulfate,presentin the separationsprocessstreams,and metal oxides (principallyUO3andU3Os)producedat the end of the separationsprocess. Small amountsof otherchemical forms are presenton the site for use in researchwork, primarilyat the SavannahRiver Laboratory(SRL). Naturallyoccurringuraniumis present in SRS soil andwaterprincipallyas metaloxides. Uraniumreleases haveoccurredprincipallyfromfuel fabricatior andspentfuel processing facilities. Smallerreleases have occurredfromwaste storageandresearchareas. These releases haveoccurredto the atmosphere,site streams,andthe ground.The majorityof these havebeen predictedreleases resultingfromsuch unavoidablesituationsas the natural imperfectionof filtrationmedia. This Chapterdescribesthe origins of documenteduraniumreleases andtheir routes tothe environment. These are releases thatwere anticipatedandwere measuredeitheras uraniumor as partof a gross.alphameasurement. Chapter2. Uranium Releasesto the Environment Specific Uranium Analysesand Unidentified Alpha Some SRS facilities that release uranium also release However,no attemptwas made to scale any data when dual plutonium and other transuranic alpha emitting analyses were not run because no consistent correlations radionuclides. Specific radiochemicalanalyses foruranium between thedata were found. were performed to distinguish uranium releases from releases of the more hazardous transuranium elements. In Mostof the release dataweretaken fromCummins, Hetrick, some facilities, wheresignificant releases of alpha-emitting and Martin, 1991,which summarizesSRS releasescovering radionuclides were not anticipated, only gross-alpha (also the period 1954 through 1989. called unidentified or unknown alpha) analyses were performed to provide an indication of the presence of Releases of radioactivity are expressed in curies. To unexpected alpha emitters. The release tables in this estimate thecorrespondingweightofreleased uranium,the Chapterindicate which values are derived fromuranium-specific activity for the given isotopic mixture must be specific radiochemical analyses and which were derived calculated.For the"natural"uranium(99.27%z_U, 0.7?'_ fromgross-alpha analyses, ln onefacility,theSRLseepage _U, and 0.0055% _U), this specific activity i,, basins, bothanalyses wereperformed overa 10-year period. 692nanocuries pergram(3190pou nds/curie). 1.7 x 10"_-curies.This is the equivalent of about 80 g of (J 4e-5 ,.o natural and depleted uranium during the time of the measurementsor, roughly, 6 rag/day 2e-5 M-Area Releasesto Streams

Prepared fearthe U. S. Department of F.nerRyunder contract Iqo. DE-AC09-B9SR18035 DI,STRIBUTION OF THIS DOCUMENT IS UNLIMITED pip imeul_oe_lly left blank. TOC-4 mIJ_,n Concentrations and Dosesin Air 5-22 Concentrations in Groundwater 5-22 Concentrations and Dosesin OffsiteSurfaceand PotableWaters 5-22 Summary of Dosime_ic Impac'ts 5-..24 References for Chapter 5 5-25 Appendix A-Physical, Chemical and Biological Properties of Iodine A-1 Ph_ical Properties A-1 Chemicaland Biological Properties A-1 Propertiesin NuclearReactorAccidents A-2 References for AppendixA A-3 Appendix B-Environmental Samp;ing and Analysis B-1 RoutineSiteOperatingConditions B-1 Air B-1 Rain B-1 Milk S-2 Groundwater B-2 SurfaceWater B-2 F._uent Outfdb I_rom I'rocm Arm B-3 SiteSm_m Ssvsnn_ Rivet' Other Environmental Media B-3 Emergency Response Conditions B-3 WeatherInforrnalJon andDisplaySystem B-3 RadiolosJcal Assistance ProsramLabcwatory B-3 Trackin8Radioactive Atmospheric Contaminants Laboratc_ B-4 FieldSampleCollectionTeams 8-4 Bibliography i mmi_n TOC-5 pap intentionallyleft blank.

Cesium in the Sa'_,annahRiver Site Environment is published as a part of the Radiological Assessment Program (RAP). lt is the fourth in a series of eight documents on individual radioisotopes released to the environment as aresult of Savannah River Site (SRS) operations. The earlier documents describe the environmental cortsequences of tritium, iodine, and uranium. Documents on plutonium,strontium, carbon, and technetium will be published in the future. These are dynamic documents andcurrent plans call for revising and updating each one on a two-year schedule. Radiocesium exists in the environment as aresult of above-ground nuclear weapons tests, the Chemobyl accident, the destruction of satellite Cosmos 954, small releases from reactors and reprocessing plants, and the operationof industrial, medical, andeducational facilities. Radiocesium has been produced at SRS during the operation of five production reactors. Several hundred curies of _TCswas released into streams in the late 50s and 60s from leaking fuel elements. Smaller quantifies were released from the fuel reprocessing operations. About 1400Ciof lrPCswas released to seepagebasins where it was tightly boundby clay in the soil. A much smallerquantity, about four Ci, was released to the atmosphere. Radiocesium concentration andtransport mechanisms for atmospheric, surface water, and groundwater have _en extensively studied by Savannah River Technology Center (SRTC) and ecological mechanisms have been studied by Savannah River Ecology Laboratory (SP, EL). The overall ngliological impactof SRS releases on the offsite maximum individual can be characterizedby total dosesof 0.33 nuem (atmospheric)and 60 mrem (liquid), compared with a dose of 12,960 nare_ fromtmn-SRSsouree_ duringthe same period of time. Isotope _r_Cs releases haveresultedin a negligiblerisk to the environment and the population it supports.

Cesium in the Sa'_,annahRiver Site Environment is published as a part of the Radiological Assessment Program (RAP). lt is the fourth in a series of eight documents on individual radioisotopes released to the environment as aresult of Savannah River Site (SRS) operations. The earlier documents describe the environmental cortsequences of tritium, iodine, and uranium. Documents on plutonium,strontium, carbon, and technetium will be published in the future. These are dynamic documents andcurrent plans call for revising and updating each one on a two-year schedule. Radiocesium exists in the environment as aresult of above-ground nuclear weapons tests, the Chemobyl accident, the destruction of satellite Cosmos 954, small releases from reactors and reprocessing plants, and the operationof industrial, medical, andeducational facilities. Radiocesium has been produced at SRS during the operation of five production reactors. Several hundred curies of _TCswas released into streams in the late 50s and 60s from leaking fuel elements. Smaller quantifies were released from the fuel reprocessing operations. About 1400Ciof lrPCswas released to seepagebasins where it was tightly boundby clay in the soil. A much smallerquantity, about four Ci, was released to the atmosphere. Radiocesium concentration andtransport mechanisms for atmospheric, surface water, and groundwater have _en extensively studied by Savannah River Technology Center (SRTC) and ecological mechanisms have been studied by Savannah River Ecology Laboratory (SP, EL). The overall ngliological impactof SRS releases on the offsite maximum individual can be characterizedby total dosesof 0.33 nuem (atmospheric)and 60 mrem (liquid), compared with a dose of 12,960 nare_ fromtmn-SRSsouree_ duringthe same period of time. Isotope _r_Cs releases haveresultedin a negligiblerisk to the environment and the population it supports.

Specific activity models are frequently used to estimate the concentration of tritium oxide in vegetation. In such models, a single value represents the ratio (R) of the specific activity of tritium oxide in vegetation to the specific activity of atmospheric tritium oxide. Federal agencies such as the Nuclear Regulatory Commission and the Environmental Protection Agency have not established a consensus default for R. Literature on this topic suggests that a site-specific distribution of R should be developed when feasible. In this study, a distribution of R is established for the Savannah River Site. Environmental tritium concentrations in air and vegetation measured on and around the Savannah River Site over a 9-y period form the basis for the analysis. For dose assessments of chronic atmospheric tritium releases at the Savannah River Site, R is best parameterized by a normal distribution with a mean of 0.54 and one standard deviation of 0.10. The Nuclear Regulatory Commission default for R is approximately equal to the Savannah River Site site-specific estimate. Based on the results, the default value for R recognized by the Environmental Protection Agency overestimates tritium concentrations in vegetation and, therefore, doses from foodstuff consumption pathways at humid sites. For the Savannah River Site, the magnitude of the error is on the order of a factor of 2. This consideration may be important if an estimated dose approaches an as-low-as-reasonably-achievable or regulatory threshold. Conversely, without the benefit of site-specific data, ingestion doses may be underestimated in regions with dry climates.