Safety Evaluation Report, Vol 3
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Department of Energy Washington, DC 20585 QA: N/A DOCKET NUMBER 63-001 October 16, 2009 ATTN: Document Control Desk John H. (Jack) Sulima, Project Manager Project Management Branch Section B Division of High-Level Waste Repository Safety Office of Nuclear Material Safety and Safeguards U.S. Nuclear Regulatory Commission EBB-2B2 11545 Rockville Pike Rockville, MD 20852-2738 YUCCA MOUNTAIN - REQUEST FOR ADDITIONAL INFORMATION - SAFETY EVALUATION REPORT, VOLUME 3 - POSTCLOSURE CHAPTER 2.2.1.3.4 - RADIONUCLIDE RELEASE RATES AND SOLUBILITY LIMITS, 4TH SET - (DEPARTMENT OF ENERGY'S SAFETY ANALYSIS REPORT SECTION 2.3.7) Reference: Ltr, Sulima to Williams, dtd 9/28/2009, "Yucca Mountain - Request for Additional Information - Safety Evaluation Report, Volume 3 - Postclosure Chapter 2.2..1.3.4 - Radionuclide Release Rates and Solubility Limits, 4th Set - (Department of Energy's Safety Analysis Report Section 2.3.7)" The purpose of this letter is to transmit the U.S. Department of Energy's (DOE) responses to the Requests for Additional Information (RAI) identified in the above-referenced letter. Each RAI response is provided as a separate enclosure. Most of the DOE references cited in the RAI responses have previously been provided with the License Application (LA), the LA update, or as part of previous RAI responses. The references provided with previous RAI responses are identified within the enclosed response reference sections. The DOE references cited in the RAI responses, which have not been previously provided to the Nuclear Regulatory Commission, are included with this submittal. There are no commitments in the enclosed RAI responses. If you have any questions regarding this letter, please contact me at (202) 586-9620, or by email [email protected]. Jeffrey R. Williams, Supervisor Licensing Interactions Branch Regulatory Affairs Division OTM: CJM-0033 Office of Technical Management _ Printed with soy ink on recycled paper John H. (Jack) Sulima -2- October 16, 2009 Enclosures (6): 1. Response to RAI Volume 3, Chapter 2.2.1.3.4, Set 4, Number 1 2. Response to RAI Volume 3, Chapter 2.2.1.3.4, Set 4, Number 2 3. Response to RAI Volume 3, Chapter 2.2.1.3.4, Set 4, Number 3 4. Mertz, C.J.; Finch, R.J.; Fortner, J.A.; Jerden, J.L., Jr.; Yifen, T.; Cunnane, J.C.; and Finn, P.A. 2003. Characterizationof Colloids Generatedfrom Commercial Spent Nuclear Fuel Corrosion.Activity Number: PAWTP30A. Argonne, Illinois: Argonne National Laboratory. ACC: MOL.20030422.0337. 5. SNL (Sandia National Laboratories) 2007. EBS Radionuclide TransportAbstraction. ANL- WIS-PA-000001 REV 03 ERD 02. Las Vegas, Nevada: Sandia National Laboratories. ACC: DOC.20090623.0001. 6. Wilson, C.N. 1990. Results from NNWSISeries 3 Spent Fuel Dissolution Tests. PNL-7170. Richland, Washington: Pacific Northwest Laboratory. ACC: NNA. 19900329.0142. John H. (Jack) Sulima -3- .October 16, 2009 cc w/encl: J. C. Chen, NRC, Rockville, MD J. R. Cuadrado, NRC, Rockville, MD J. R. Davis, NRC, Rockville, MD R. K. Johnson, NRC, Rockville, MD A. S. Mohseni, NRC, Rockville, MD N. K. Stablein, NRC, Rockville, MD D. B. Spitzberg, NRC, Arlington, TX J. D. Parrott, NRC, Las Vegas, NV L. M. Willoughby, NRC, Las Vegas, NV Jack Sulima, NRC, Rockville, MD Christian Jacobs, NRC, Rockville, MD Lola Gomez, NRC, Rockville, MD W. C. Patrick, CNWRA, San Antonio, TX Budhi Sagar, CNWRA, San Antonio, TX Bob Brient, CNWRA, San Antonio, TX Rod McCullum, NEI, Washington, DC B. J. Garrick, NWTRB, Arlington, VA Bruce Breslow, State of Nevada, Carson City, NV Alan Kalt, Churchill County, Fallon, NV Irene Navis, Clark County, Las Vegas, NV Ed Mueller, Esmeralda County, Goldfield, NV Ron Damele, Eureka County, Eureka, NV Alisa Lembke, Inyo County, Independence, CA Chuck Chapin, Lander County, Battle Mountain, NV Connie Simkins, Lincoln County, Pioche, NV Linda Mathias, Mineral County, Hawthorne, NV Darrell Lacy, Nye County, Pahrump, NV Jeff VanNeil, Nye County, Pahrump, NV Joe Kennedy, Timbisha Shoshone Tribe, Death Valley, CA Mike Simon, White Pine County, Ely, NV K. W. Bell, California Energy Commission, Sacramento, CA Barbara Byron, California Energy Commission, Sacramento, CA Susan Durbin, California Attorney General's Office, Sacramento, CA Charles Fitzpatrick, Egan, Fitzpatrick, Malsch, PLLC ENCLOSURE 1 Response Tracking Number: 00568-00-00 RAI: 3.2.2.1.3.4-4-001 RAI Volume 3, Chapter 2.2.1.3.4, Fourth Set, Number 1: Explain why the igneous scenario TSPA model does not consider potential generation of greater quantities of waste form colloids in the igneous intrusive case, relative to the nominal case. Basis: The response to RAI 3.2.2.1.3.4-1-002 and RAI 3.2.2.1.3.4-1-002 Supplemental Question explains that the igneous intrusive modeling case generally has generation of greater quantities of colloids than the nominal case because the igneous intrusion modeling case results in a higher rate of advection. The higher water volume from the higher rate of advection gives greater quantities of colloids at fixed concentrations in the aqueous phase. Colloids could form in greater quantities for other reasons; for example: 1. Large settled particles of oxidized commercial and DOE spent nuclear fuels with a large total surface area could form, as summarized in the RAI responses. These oxidized particles could continue to dissolve (NRC 2008, page 8) at high rates in later seepage water due to their high total surface area. This further dissolution of oxidized spent fuel could result in the faster formation of stable phases such as schoepite in precipitates or colloids. 2. HLW glass could become altered by hydration in the early humid environments. The hydrated alteration layer will remain on the glass surface until contacted and transported by later seepage water [after BSC, 2004, p. 6-30]. This fast dissolution and transport of the alteration layer may result in the faster formation of stable crystalline phases such as smectite in precipitates or colloids. 3. There are considerable uncertainties in the interaction of waste form and dike, including chemical reactions of waste form with metals and basalt magma (SNL, 2007, 6.4.8.3.3). It is not clear how these interactions, and their likelihood, might affect colloid generation and colloid mass concentrations. The interacted phases may further dissolve and become more stable phases in precipitates or colloids. Lastly, it is unclear how the colloid release model was stochastically treated in terms of the igneous event probability in the igneous scenario TSPA model. Page 1 of7 ENCLOSURE I Response Tracking Number: 00568-00-00 RAI: 3.2.2.1.3.4-4-001 1. RESPONSE The igneous intrusion modeling case is not expected to create greater concentrations of colloidal actinides than the nominal modeling case. This explanation is based on process-level considerations, as previously discussed in the response to RAI 3.2.2.1.3.4-1-002, Supplemental Question, as well as on a discussion that considers the risk significance of the three possible mechanisms proposed in the current RAI. The risk-informed explanation compares the nominal/seismic case, which is called the seismic ground motion modeling case, with the igneous intrusion case. The seismic ground motion modeling case is the most risk-significant modeling case for the first 10,000 years, and is equal in risk significance to the igneous intrusion case at the peak of the post-10,000-year dose (SNL 2008, Figure 8.1-3[a]). -Note that, as explained in Section 6.1.2 of the Total System PerformanceAssessment Model lAnalysis for the License Application (TSPA-LA) report (SNL 2008), the nominal modeling case dose is not added into the total dose calculation because its probability is negligible; rather, nominal processes are part of the seismic ground motion modeling case. (Note: this response concentrates on plutonium because it is the most risk-significant colloidal actinide.) 1.1 SPENT FUEL COLLOIDS The first scenario listed in the RAI postulates that colloids could be produced in larger quantities from fast dissolution of large settled particles of oxidized commercial spent nuclear fuel (SNF) and DOE-owned SNF. However, it is not expected that colloids will be produced in larger quantities for the following reasons: (1) The state of the fuel, when water first flows through the waste package, will be similar for both the seismic ground motion modeling case (i.e., the nominal/seismic case) and the igneous intrusion modeling case (Section 1.1.1). (2) Faster dissolution does not necessarily result in greater plutonium colloid concentrations in the bulk solution, because the majority of the plutonium remains in a residue layer at the reaction front (Section 1.1.2). (3) The colloid model, and the associated aqueous colloid concentration range, are conservative (Section 1.1.3). 1.1.1 State of the Fuel at Time of First Water Flow In the seismic ground motion modeling case, the packages are breached by stress corrosion cracks (that do not allow advective water flow) many thousands of years before they are breached by general corrosion patch openings (which do allow advection). The fuels are exposed to air and water vapor long enough to be converted to hydrated uranium (VI) minerals (dehydrated schoepite) before water flow is initiated. These minerals may exist as colloidal-sized particles initially, but will be converted into mats of crystals that are tens to hundreds of micrometers in length within a few years, as seen in drip tests by Wronkiewicz et al. (1992, Section 3.3), and as seen by Taylor et al. (1995) in air-steam mixtures that were moisture-saturated. Page 2 of 7 ENCLOSURE 1 Response Tracking Number: 00568-00-00 RAI: 3.2.2.1.3.4-4-001 During an igneous event, the waste package is assumed to be fully breached, and the fuel will be exposed to temperatures of up to 1,150'C in the presence of magmatic gasses (SNL 2007a,, p.