ML20115E497

Second Round of Comments on U.S. Department of Energy West Valley Demonstration Project'S Final Study Document: Vitrification Facility Air Emissions During Open-Air Demolition, Measured Vs Predicted, WVDP-579, Rev. 0 (Docket No. 05000201 (P

ML20115E497
Person / Time
Site:	West Valley Demonstration Project, P00M-032
Issue date:	04/27/2020
From:	Amy Snyder Division of Decommissioning, Uranium Recovery and Waste Programs
To:	Bower B US Dept of Energy, West Valley Demonstration Project
Snyder A
References
WVDP-579, Rev 0
Download: ML20115E497 (8)

Text

UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 April 27, 2020 Bryan C. Bower, Director West Valley Demonstration Project U.S. Department of Energy 10282 Rock Springs Road West Valley, NY 14171-9799

SUBJECT:

SECOND ROUND OF COMMENTS ON U.S. DEPARTMENT OF ENERGY WEST VALLEY DEMONSTRATION PROJECTS FINAL STUDY DOCUMENT:

VITRIFICATION FACILITY AIR EMISSIONS DURING OPEN-AIR DEMOLITION, MEASURED VS PREDICTED, WVDP-579, Rev. 0 (DOCKET NO. 05000201 (POOM-032))

Dear Mr. Bower:

The U.S. Nuclear Regulatory Commission (NRC) staff has reviewed the U.S. Department of Energys (DOE) February 19, 2020, response (Agencywide Document Access and Management System (ADAMS) Accession No. ML20055E049) to NRCs December 4, 2019, comments (ADAMS Accession No. ML19319A293) on the DOEs Vitrification Facility Air Emissions During Open-Air Demolition, Measured vs. Predicted, WVDP-579, Rev. 0 (the Validation Study)

(ADAMS Accession No. ML1926A214), dated September 5, 2019).

The intent of our review of the Validation Study and our attached second set of comments is to provide comments with respect to the DOEs proposed use of the results of the validation study to update the AERMOD1 modeling used to support the Main Plant Process Building (MPPB) demolition. WVDP-586, Revision 3, "West Valley Demonstration Project Main Plant Process Building (MPPB) Decommissioning & Demolition Plan" (ADAMS Accession No. ML19267A215) documents DOEs plan for demolition of the MPPB. The staff requests additional information on the planned use of updated2 AERMOD modeling to determine when the MPPB is open-air demolition ready. Because AERMOD modeling results will be used to inform health and safety decisions, changes to the AERMOD modeling specific to implementing the MPPB Work Plan should be well understood and supported and should ensure adequate protection of public health and safety. DOE should reexamine the changes to the modeling approach considering the staffs comments provided in the enclosure. DOE could also provide additional information on how its proposed methodology will mitigate modeling uncertainties and ensure adequate protection of public health and safety (e.g., through built-in safety margin, monitoring, and controls during demolition).

In accordance with Title 10 of the Code of Federal Register Part 2.390 of the NRCs Agency Rules of Practice and Procedure, a copy of this letter will be available electronically for public inspection in the NRC Public Document Room or from the Publicly Available Records 1

AERMOD stands for American Meteorological Society/Environmental Protection Agency Regulatory Model.

2 Updates to the model based on the results of the validation study include updates to AERMOD modeling parameters (e.g., release fraction, moisture content, and physical state factor).

B. Bower component of NRCs ADAMS. ADAMS is accessible from the NRC Web site at http://www.nrc.gov/reading-rm/adams.html.

If you have any questions or need any additional information regarding our comments, please contact me at 301-415-6822.

Sincerely, Digitally signed by Amy M.

Amy M. Snyder Snyder Date: 2020.04.27 14:24:32

-04'00' Amy M. Snyder, Senior Project Manager Materials Decommissioning Branch Division of Decommissioning, Uranium Recovery and Waste Programs Office of Nuclear Material Safety and Safeguards Docket: 50-00201, POOM-32 ENCLOSURE: NRC Staff Comments cc: WVDP List Serv

ML20115E497 *via e-mail OFFICE DUWP DUWP DUWP DUWP NAME ASnyder* CMcKenney* BWatson* ASnyder*

DATE 4/24/2020 4/24/2020 4/24/2020 4/27/2020 NRC STAFF COMMENTS General Comment It is the U.S. Nuclear Regulatory Commission (NRC) staffs understanding that AERMOD modeling will be used to support open-air demolition of the MPPB. NRC understands that based on the Main Plant Process Building (MPPB) Work Plan, AERMOD modeling results will be used to inform health and safety decisions such as whether demolition approaches used in a specific area, fixative applications, and misting controls-separate are not resulting in contamination above administrative controls.

Page 60-61 of the MPPB Work Plan, states:

The action levels at the WVDP site perimeter will be 0.02 Derived Air Concentration (DAC) which is the maximum weekly average concentration according to the AERMOD calculation and activity on the deposition mats of 20 dpm/100cm2 alpha and 1000 dpm/100cm2 beta-gamma. The 0.02 DAC comes from the DAC values provided in 10 CFR 835 that would trigger mandatory personnel monitoring (100 person-mrem/yr) and the contamination levels are the levels for a Contamination Area (CA), which the intent is to remain below in the area outside the CA boundary. AERMOD modeling of residual contamination obtained from radiological surveys will be used to determine if contamination-including the demolition approaches used in a specific area (Cut, Shear, Break, Drop), fixative applications, and misting controls-will ensure that DAC objectives are met (0.02 DAC at the WVDP site perimeter).

Wind speed and stability class limitations will be provided in the demolition WIP.

The approach to use the 0.02 DAC appears reasonable. Could DOE confirm what controls will be in place and at what level action will be taken to address issues associated with greater than expected air concentrations and dose to workers and members of the public during demolition of the MPPB? For example, alerts were established prior to a stop work established at 3 derived air concentration (DAC)-hour per day for the vitrification facility demolition.

Additionally, action levels of 0.02 DAC at the security fence and activity on deposition mats of 20 dpm/100 cm2 alpha and 1000 dpm/100 cm2 beta-gamma have also been proposed for the MPPB demolition. How often will the deposition mats be monitored?

The actions levels provide significant safety margin and allow action to be taken in a timely manner to minimize exposure should the expected dose be significantly under-estimated. These controls would help mitigate uncertainty with AERMOD modeling to allow DOE to proceed with open air demolition of the main plant process building NRC suggests that DOE considers the NRC specific suggestions below specific to the AERMOD model that DOE plans to use for the MPPB demolition.

Enclosure

Specific Comments on the West Valley Demonstration Project Vitrification Facility Validation Study RAI Responses in Relationship to the Main Plant Process Building Comment DOE Response New Comment New N/A 1.a.2 NRC requested clarification regarding While the risk from C-14, I-129, and the selection of radionuclides in the Tc-99 may be low, some form of model validation study. DOE consideration of dose from these contractors stated Tc-99 and I-129 radionuclides appears necessary to were not analyzed because they are make that determination given they not listed in the characterization are listed as key radionuclides. For database; however, DOE has listed the MPPB AERMOD, please address these as key radionuclides and how the dose from C-14, I-29, and Tc-provided NESHAPS calculations using 99 were considered if eliminated from the alternative methodology for these the models.

key radionuclides. Furthermore, C-14, Tc-99 and I-129 are listed as key radionuclides in the DOE Phase I decommissioning plan.

1.b.1 and In response to NRCs questions about Clarify if all radionuclides are treated 1.b.2 presence of gaseous forms of as particulates. Specifically, clarify radionuclides and ability to validate how Cs-137 and other radionuclides model predictions for these that are assumed to be volatilized radionuclides, DOE contractors during hot cutting activities are treated respond that they are unaware of in the modeling (i.e., as gases and/or gaseous emissions, but if there were, particulates). Also, confirm that they would be assumed to be particle size and deposition are not volatilized with an emission factor of considered in the modeling and how 100 percent and so there would be this influences the results of the nothing to validate. However, validation study (e.g., location of radionuclides are assumed to be samplers) and estimation of dose in volatilized during certain activities (e.g., general (e.g., impact on dose Cs-137 during hot-cutting) and it is estimates for external radiation and unclear that 100 percent of these inhalation exposure).

radionuclides are assumed to be volatilized making the relevance of this statement unclear.

2.a NRC was concerned that only two Suggest providing figures of modeled 2.d.1 discrete data points were used to plume distributions to support general validate the model and recommended predictive capability of the model in additional air sampling data be used to comparison to measured data. Air assess the predictive performance of monitoring data collected within and the model. NRC went on to state that outside the 30-m contamination area results could be comparable at the two boundary, as well as data collected discrete points and still not corroborate from deposition mats could be used the model or could be way off at the for a qualitative comparison to assess two discrete points but generally the predictive capability of the model consistent with plume distributions from to simulate atmospheric transport of the model.

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radioactivity from the demolition Response 2.d.1 states that there were sources to downwind locations.

several issues with using other air samplers including (i) higher detection AERMOD can consider building wake limits, and (ii) location in building wake effects so the relevance of samplers zones. being subject to building wake affects as an argument for not including these samplers does not appear to be compelling. Further, it is unclear if meteorological data that was used to determine the validation study sampling locations are representative of conditions during demolition. For example, if most demolition activities occurred during the day3 and meteorological data are collected over day and night time hours, then the wind rose data may not be representative of the hours during which most of the demolition activities occur. Additionally, meteorological towers are typically located in areas free of obstructions. Because the wind direction near the demolition site may be influenced by nearby obstructions, the wind rose data from the onsite meteorological tower may not be reflective of conditions at the demolition site.

Additionally, particle and gaseous deposition does not appear to be considered in the modeling, although particle size and chemical form are expected to influence atmospheric transport. Information on the physical and chemical form of the radioactivity would have been helpful in siting the validation study samplers.

Also depending on the release height of sources, building wake effects, and buoyancy effects (e.g., from hot cutting activities), the locations of the samplers may not have been optimally located.

While AERMOD modeling may be conservative with respect to dose, the 3

Debris pile emissions occur at all times of the day, while other activities generally occur during the day.

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purpose of a validation study that uses actual monitoring data to make parameter adjustments to match the data inherently presumes that the model is realistically simulating atmospheric transport. Additional information would be needed to support the changes to air release fractions for hydraulic hammering and other parameters (moisture content for debris piles and physical state factor for hot cutting) to ensure that the AERMOD estimated air concentrations are reasonably conservative considering the significant uncertainty in the model and limited data provided to support the modeling adjustments.

With respect to addressing hydraulic hammering and other parameters noted above for the MPPB demolition, the NRC staff suggest DOE evaluate these aspects for the AERMOD model used for the MPPB demolition. NRC anticipates that DOE will execute its plan, as identified in the MPPB Work Plan on page 60-61 and 57 to ensure that workers and members of the public will be protected during open air demolition due to the large safety margin and controls that will be in place during demolition of the MPPB.

5.a NRC questioned whether adequate NRC notes that the changes to the basis was provided to support the model parameters for hot cutting changes in hot cutting parameters. For should be demonstrably conservative example, limited data were available, if the uncertainty in model predictions and NRC identified several limitations is significant and cannot be reduced of the validation study. NRC inquired if (the updated modeling results were comparisons of Cs-137 concentrations sometimes slightly lower and slightly would be more useful to justify changes higher than positive detections at in model parameters. offsite sampling locations during hot The response provided information cutting activities and therefore not about detections at offsite samplers, clearly conservative). For example, it which were compared to model results appears that the modeling only using updated parameters. While considers particulate release (see updated model results using updated comment 1.b.1 and 1.b.2 which seeks parameters were like monitoring results clarification on treatment of volatile at offsite samplers, the adequacy of radionuclides) although radionuclides these changes given uncertainty in the are assumed to be volatilized during model predictions is unclear. hot cutting activities. The degree to which the released fraction is volatilized, the extent to which this 4

radioactivity is transported as a gas, and the point at which this material condenses back to form solid particulates are unknown and do not appear to be considered in the modeling. Therefore, comparison of modeling results with particulate measurements at significant downwind distances does not appear to be enough to assess the adequacy of the predictive capability of the model.

General When responding to an NRC question In previous documentation, CAP88 comment about offsite model validation, DOE was stated to be used to estimate 3 contractors stated that CAP88 is not doses to offsite members of the public used to calculate dose and that offsite in determining whether the facility was monitoring data are used as reported in open air demolition ready. While the Annual Site Environmental Reports offsite data may be used to calculate (ASER). dose for the purpose of the ASER, please clarify the use of CAP88 to estimate offsite doses prior to building demolition for the Vitrification Facility and Main Plant Process Building.

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