ML18331A024

Enclosure 1 - Response to RAI Enviro-26

ML18331A024
Person / Time
Site:	La Crosse  File:Dairyland Power Cooperative icon.png
Issue date:	11/15/2018
From:	LaCrosseSolutions
To:	Office of Nuclear Material Safety and Safeguards
References
LC-2018-0075
Download: ML18331A024 (76)

Text

Enclosure 1 to LC-2018-0075 Response to RAI ENVIRO-26 (75 pages)

Enclosure 1 to LC-2018-0075 Page 1 of 26 RAI ENVIRO-26 On March 12, 2018, Solutions notified the NRC regarding the detection of tritium above background levels in site groundwater wells. In order to describe the site and the potential impacts of decommissioning on the environment including tritium in the groundwater, the NRC staff needs additional information to complete its Environmental Assessment.

Provide the following information regarding the event:

1) Describe the likely cause of the tritium in the groundwater, timeframe of the release, where the release occurred, and how it was found.

LACBWR Response:

The tritium in the groundwater is believed to be associated with exhaust from ventilation systems, employed during decontamination and demolition activities within the Reactor Building starting in November 2017. The exhaust impacted ice/snow melt on frozen ground existing approximately four feet below the exhaust point. During rain events, the impacted ice/snow melt flowed from its location below the ventilation discharge point at the southeast side of the Reactor Building, across the ground surface into the former Reactor Plant/Generator Plant Area (RPGPA) sump, located southwest of the Reactor Building, The lowest point of the excavation at the former RPGPA sump is below the water table and the excavation has been kept open by the placement of a trench box. The bottom of the former RPGPA sump area is therefore in direct communication with the shallow aquifer. It should be noted that more recently, the bottom of the excavation had filled in with several feet of soil and the trench box was removed, but the bottom of the excavation was still below the water table. The excavation received the condensate/tritium from the ventilation and is likely the point source for the resulting groundwater plume.

Observations of erosional rills and flow pathways during heavy rains and snow melt confirmed that the runoff was collected in the sump excavation, which was excavated to below the water table, as confirmed by the standing water present within the excavation. The RPGPA Sump is located upgradient from the MW-203A and MW-203B monitoring well pair.

In December 2017, elevated concentrations of tritium (13,000 pCi/L) were detected in groundwater samples from MW-203A, as part of the semi-annual groundwater monitoring program. Once detected, and as part of the investigation of the cause of the elevated tritium levels in MW-203A, the ice/snow melt/standing water impacted by exhaust from the Reactor Building Ventilation System was sampled and found to contain tritium concentrations up to approximately 237,000 pCi/L. Upon determining the tritium levels associated with the ice/snow melt, in March 2018, the ventilation system exhaust was modified and the condensate was treated as liquid rad waste. Thus, the bounding end time of release to the ground was in March 2018, when no additional tritium was introduced to the ground or into the RPGPA excavation. Groundwater samples have been collected on a monthly basis since then and will continue through December 2018.

Enclosure 1 to LC-2018-0075 Page 2 of 26

2) Provide a bounding amount of radioactive material released to the environment as a result of the unplanned release. What is the chemical form, concentration, and isotopic content of the material released?

LACBWR Response:

As indicated in the response to Item #1, tritium was found in the ice/snow melt impacted by the Reactor Building Ventilation system at levels up to 237,000 pCi/L, resulting in a maximum groundwater tritium level of 24,200 pCi/L in Monitoring well MW-203A. The ventilation exhaust was modified and the condensate was collected, and the resulting tritium levels decreased. Although the source area was been identified, the volume and total amount of tritium release and storm water runoff volumes are unknown.

Monitoring well pair MW-203A/B was installed to characterize groundwater downgradient from the sump and some floor drains of the Turbine Building, because it was identified as an area where site-related constituents could have been released. Prior to the release described above, all groundwater data was reported at background conditions or non-detect values for non-radiological constituents.

As provided in the Site Investigation Work Plan, Solutions is in the process of completing the characterization of the tritium release. This includes a numerical groundwater model to predict flow pathways and velocity and a dye tracer study to confirm the source area and to calibrate the model.

The dye tracer study was performed using a known volume and concentration of rhodamine-WT (RWT), which was introduced into the RPGPA sump excavation. A minimal amount of dye was used so that it would not be visible along the shoreline or potentially impact the deeper supply wells on site. Sample packets were placed in all site wells and along the shoreline to be able to detect very small concentrations of RWT. Although, one carbon sampling packet was secured along the river edge along the project pathway of the plume, that data point is not critical to the models calibration, as the goal of the model was to confirm the source area and better understand groundwater velocities.

On June 28, 2018, the Wisconsin Department of Natural Resources approved performance of the dye tracer study, and ES and Haley & Aldrich initiated the test the week of July 9, 2018, following the July groundwater sampling event. MW-203A/B was installed to be downgradient from the RPGPA Sump (and the presumed source) based on our understanding of site groundwater flow. This is further supported by the initial data from the dye tracer study. RWT was detected within two weeks of its introduction into the RPGPA and reached a maximum concentration after within three weeks.

Concentrations, as expected, are currently decreasing as shown in Table 1.

Enclosure 1 to LC-2018-0075 Page 3 of 26 Table 1. Dye Study Results Station Number Background Samples Rhodamine-WT Results (ppb)

Date Placed 03/08/18 07/12/18 07/19/18 07/26/18 08/02/18 08/09/18 Date Collected 03/16/18 7/10/2018 07/19/18 07/26/18 08/02/18 08/09/18 08/16/18 201-A - - ND ND ND ND ND 202-B ND - ND ND ND ND ND 202-AR - - ND ND ND ND ND 203-A ND - ND 54.4 529 84.1 12.3 203-B ND - ND ND ND ND ND 204-B - - ND ND ND ND ND 204-A - - ND ND ND ND ND Well-5* - ND ND ND ND ND ND Well-7* - ND ND ND ND ND ND Well-3* - ND ND ND ND ND ND River - - ND ND ND ND ND Notes:

0.5 pounds of WRT was introduced on 7/12, flushed with approximately 250 gallons of non-chlorinated water

• Water samples submitted, collected when sample packets were collected.

ppb indicates parts per billion ND indicates non detect

" - " indicates not sampled The predicted pathway from the preliminary model is presented below. Please note that for the preliminary model, the area of the source area is larger than the actual sump, resulting in a wider plume area.

Enclosure 1 to LC-2018-0075 Page 4 of 26 Although the site condition for the dye introduction in early July 2018 was slightly different than those of Winter 2017, due to seasonal variations and the filling in of sediments via likely sidewall cave-ins, and stormwater runoff into the former sump area, the model estimated the volume of and concentration of impacted stormwater/snow melt that likely entered the former RGPGA sump at a total of 46,000 gallons of 60,000 pCi/L. This volume would include storm water collection over approximately two months (including snow melt). Once in the RPGPA sump area, the tritium was in hydraulic communication with the shallow aquifer and the plume migrated towards the river.

This then lead to an estimated peak concentration of approximately 60,000 pC/l in groundwater, and at approximately 10,000 pCi/Lat the point of discharge to the Mississippi River, well below the EPA MCL of 20,000 pCi/L.

3) Does the Final Site Survey cover the area where the release occurred? Explain how the surveying and/or sampling will identify any radiological material remaining on the soil as a result of the demolition activities.

LACBWR Response:

Survey unit L1-010-102 is directly west of the Reactor Building, where the release occurred, and includes the soil beneath and adjacent to the Turbine Building. Also included within survey unit L1-010-102 is the RPGPA sump, located southwest of the Reactor Building and in the eastern portion of the survey unit. In February of 2018, the Turbine Building foundation was removed in its entirety, including the RPGPA sump and adjacent soil. Because of accessibility issues and background interference from the Reactor Building, the areas beneath the Turbine Building, including the RPGPA sump, have been further divided into two survey units (east and west). The soil from beneath the west portion of the Turbine Building was sampled as part of the FSS Plan for survey unit L1-010-102 (L1-SUB-TDS). A total of eight (8) soil samples were collected from the region beneath the broken drain lines, turbine sump, turbine pit, and condenser pit and sent to an off-site laboratory for hard-to-detect (HTD) analysis. One of the samples was tested for Sr-90, while the other seven samples were analyzed to the full suite of ROC which included H-3. None of the samples identified any HTD radionuclides of concern (ROC), including H-3, above the minimum detectable activity (MDA). The sample plan and results have previously been provided to the NRC as part of the RAI response package.

The east portion of the survey unit, which includes the location of the former RPGPA sump, will undergo continuing characterization and FSS in September of 2018. A sample and analysis plan will be developed similar to that described above for the west portion of the excavation and will be provided to the NRC for information and the results provided for evaluation.

The surveying and/or sampling will be adequate to identify any radiological material remaining on the soil as a result of the demolition activities. A gamma scan will be performed over 100% of the excavated area, soil samples will be obtained in accordance with MARSSIM and 10% of the samples will be analyzed for HTD ROC (including H-3).

Enclosure 1 to LC-2018-0075 Page 5 of 26

4) Describe whether the demolition activities mobilized radionuclides of concern other than tritium.

Describe how the demolition activities may have impacted the established surrogate ratios for the Hard-to-Detect radionuclides.

LACBWR Response:

When a structure is demolished and the basement foundation is removed in its entirety, there is a potential for residual concrete debris to remain in the soil within the excavation. Although the site takes precautionary measures to prevent this, the continuing characterization and/or subsequent FSS is designed to assume there could be a change to the established surrogate ratios for the HTD ROC.

The interior demolition of the Reactor Building was performed with an exterior containment structure and waste loadout cell. All interior demolition activities were performed under negative HEPA ventilation of the Reactor Building and associated containment and waste loadout structures to minimize airborne particulate migration from the areas until the structure was surveyed and deemed acceptable for demolition. The HEPA ventilation was sampled during operations to monitor for air quality and HEPA filter performance. The vast majority of the demolition materials were loaded while the containment tents were present. Remaining elevated materials within the containment tent footprint have been covered with steel plates to prevent spread of materials during demolition.

Additionally, corrective actions have been implemented to reduce the potential for contamination migration. These include over excavating the surfaces beside or beneath the concrete that was removed to a minimum of one bucket depth. The soils are disposed or sifted to remove any concrete that may have been pushed through the surface while hammering or processing concrete. Materials may only be placed back in the excavation if surveyed by a FSS technician.

As described in LTP Section 5.1, in order to verify that the insignificant contributor (IC) dose does not change prior to implementing the FSS and to verify the HTD to surrogate radionuclide ratios used for the surrogate calculation are still valid, LACBWR obtains and analyzes concrete core and soil samples during continuing characterization (including radiological assessments) and FSS within each individual survey unit or area as described below.

For continuing characterization, 10% of all media samples collected in a survey unit will be analyzed for HTD radionuclides. In addition, a minimum of one sample beyond the 10% minimum will be selected at random, also for HTD radionuclide analysis. All samples will first be analyzed by the on-site gamma spectroscopy system. In the absence of detectable gamma activity, locations will be selected based on the potential for the presence of activity using Historical Site Assessment information or other process knowledge data. All samples selected for HTD analysis during continuing characterization will be analyzed for the full suite of radionuclides from License Termination Plan (LTP) Table 5-1.

The actual IC dose will be calculated for each individual sample result using the DCGLs from Revision 3 of TSD RS-TD-313196-004, Table 4 for soils and Table 35 for basement structures. If the IC dose calculated is less than the IC dose assigned for DCGL adjustment, then no further action will be taken. If the actual IC dose calculated from the sample result is greater than the IC dose assigned for DCGL adjustment, then a minimum of five (5) additional investigation samples will be taken around the original sample location. Each investigation sample will be analyzed by the on-site

Enclosure 1 to LC-2018-0075 Page 6 of 26 gamma spectroscopy system and sent for HTD analysis (full suite of radionuclides from LTP Table 5-1). As with the original sample, the actual IC dose will be calculated for each investigation sample.

In this case, the actual calculated maximum IC dose from an individual sample observed in the survey unit will be used to readjust the DCGLs in that survey unit. If the maximum IC dose exceeds 10%,

then the additional radionuclides that were the cause of the IC dose exceeding 10% will be added as additional ROC for that survey unit. The survey unit-specific DCGLs used for compliance, the ROC for that survey unit and the survey data serving as the basis for the IC dose adjustment will be documented in the release record for the survey unit.

The final ROC for the decommissioning of LACBWR are Co-60, Cs-137, Eu-152 and Eu-154, which are gamma emitters, and Sr-90 which is an HTD radionuclide. For sample(s) analyzed for HTD radionuclides during continuing characterization, if the analysis of the sample indicates positive results (greater than MDC) for both the HTD ROC (Sr-90) and the corresponding surrogate radionuclide (Cs-137), then the HTD to surrogate ratio will be derived. If the derived HTD to surrogate ratio is less than the applicable HTD to surrogate ratio from TSD RS-TD-313196-001, Table 40, then no further action is required. If the HTD to surrogate ratio exceeds the applicable ratio from TSD RS-TD-313196-001, Table 40, then a minimum of five (5) additional investigation samples will be taken around the original sample location. Each investigation sample will be analyzed by the on-site gamma spectroscopy system and then sent for HTD analysis. As with the original sample, the HTD to surrogate ratio will be calculated for each investigation sample. The actual maximum HTD to surrogate ratio observed in any individual sample will be used to infer HTD radionuclide concentrations in the survey units shown to be impacted by the investigation. The survey unit-specific HTD to surrogate ratio and the survey data serving as the basis for the ratio will be documented in the release record for the survey unit(s).

Survey unit-specific surrogate ratios, in lieu of the ratios from TSD RS-TD-313196-001, Table 40, may be used for compliance if sufficient radiological data exists to demonstrate that a different ratio is representative for the given survey unit. In these cases, the survey unit-specific radiological data and the derived surrogate ratios will be submitted to the NRC for approval. If approved, then the survey unit-specific ratios used and the survey data serving as the basis for the surrogate ratios will be documented in the release record for the survey unit.

Soil samples and concrete cores will be collected during FSS to confirm the HTD to surrogate radionuclide ratios used for the surrogate calculation. Only Sr-90 will be analyzed in the FSS confirmatory samples. Concrete cores will be collected from the Waste Gas Tank Vault basement and the Reactor Building basement where concrete will remain. The number of cores collected and analyzed for ROC HTD will be 10% of the number of FSS ISOCS measurements. The concrete core locations will be selected from the floor and lower walls in the survey unit to alleviate safety concerns from working at heights and to focus on the areas expected to contain the majority of residual radioactivity. For soil, 10% of the FSS samples collected from open land survey units (including excavations where major sub-grade structures previously resided) will also be analyzed for ROC HTD radionuclides. Additionally, if levels of residual radioactivity in an individual soil sample exceed a SOF of 0.1 (using the Operational DCGL), then the sample(s) will be analyzed for ROC HTD radionuclides. For soil samples or concrete cores with positive results for both a Sr-90 and the corresponding surrogate radionuclide (Cs-137), the HTD to surrogate ratio will be derived. The

Enclosure 1 to LC-2018-0075 Page 7 of 26 applicable ratio from TSD RS-TD-313196-001, Table 40 will be used unless specific survey information from continuing characterization supports the use of a surrogate ratio that is specific to the area. In these cases, the area-specific ratios as determined by actual survey data will be used in lieu of the TSD RS-TD-313196-001, Table 40 ratios. The area-specific ratios used and the survey data serving as the basis for the ratios will be documented in the release record for the survey unit.

5) Describe how this incident was communicated to other agencies (local, State, Federal, etc.). What were their responses and what, if any, actions were required to be taken?

LACBWR Response:

After elevated levels of tritium were detected in the December 2017 sampling of shallow groundwater monitoring well MW-203A, an additional sampling round was performed in February 2018 to confirm the presence of tritium. The February 2018 results indicated tritium levels in excess of 20,000 pCi/l in MW-203A and a detectable amount of tritium in shallow groundwater monitoring well MW-202A, and its replacement MW-202AR (both downgradient from MW-203A).

Energy Solutions (ES) issued a press release regarding its groundwater findings, having advised Dairyland Power Cooperative (DPC), the NRC, the Wisconsin Department of Public Health (DPH),

and the Wisconsin Department of Natural Resources (DNR) of its findings.

In a March 30, 2018, letter to ES, DNR outlined the actions ES was required to take:

1. Within 30 days of the DNR letter, submit written verification (e.g., a letter for the consultant) that an environmental consultant has been hired.

2. Within 60 days of the DNR letter, submit a site investigation work plan compliant with NR 700 Wisconsin Administrative Code Rule Series and current DNR technical guidance documents.

3. Within 90 days of submittal of the work plan, the site investigation activities are to be initiated.

4. Within 60 days of completion of site investigation activities and receipt of laboratory data, a site investigation report is to be submitted to DNR

5. Within 60 days of submitting the site investigation report submittal of a remedial actions options report to DNR.

ES provided confirmation to the DNR that an environmental consulting firm, Haley & Aldrich, Inc.,

was under contract. A Site Investigation Work Plan was developed and submitted to the DNR on May 29, 2018. This plan was also provided to the NRC. The plan is still under review by DNR, however; the scope of the work has been completed, with DNRs acknowledgement (i.e., written approval to RWT).

ES continues to monitor tritium levels in the affected wells and performed subsequent rounds of groundwater sampling in early April and early June. Results from these sampling events indicate that tritium levels in both wells previously exhibiting elevated levels (MW-202A/AR and MW-203A) are overall decreasing (see the attached table for historical groundwater sampling results and graphs of tritium results for MW-201A. -202A, and -203A). One element of the Site Investigation Work Plan is the performance of a dye test to confirm the site groundwater conceptual model. On June 28, 2018,

Enclosure 1 to LC-2018-0075 Page 8 of 26 the DNR approved performance of the dye test, and ES and Haley & Aldrich initiated the test the week of July 9, 2018, as part of the July groundwater sampling event.

Under an abundance of caution, DPC has ceased use of the onsite groundwater wells for potable water and is providing bottle water for drinking. No tritium (above background) or RWT dye has been detected in the supply wells.

Provide the following information regarding the site characteristics, including groundwater flow, and movement of the released material:

6) Provide information on the migration of the released material through the environment both vertically and horizontally in the soil, surface water, and groundwater. Will the material reach the River and if so, when, and in what concentrations?

LACBWR Response:

The source of the tritium detected in groundwater is believed to be the exhaust vent from the Reactor Building. Standing water on the ground below the vent was tested and contained elevated tritium.

Observations of erosional rills and flow pathways during heavy rains and snow melt confirmed that the runoff was collected in the sump excavation, which was excavated to below the water table, as confirmed by the standing water present within the excavation. However, it is possible that tritium could infiltrate the shallow soils below the ventilation exhaust and along the surface run off flow pathway, but ponding of the condensate on the ground suggests that shallow infiltration was minimal.

As indicated in the response to Item #1, the ice/snow melt, impact by the Reactor Building exhaust, flowed with storm water over the ground surface and into the excavated area in the vicinity of the former RPGPA sump, which is at an elevation below the water table (approximately 25 feet below ground surface). The tritium in the former sump was then in hydraulic communication with the shallow aquifer and migrated to MW-203A, located immediately down gradient. Following groundwater flow, the material was carried horizontally in a westward direction towards the Mississippi River, as evidenced by tritium detections at MW-202A, and its replacement MW-202AR.

Vertical flow is negligible, as indicated by no detectable tritium in samples from MW-202B and MW-203B, which are collocated with the A series wells but screened in the deeper aquifer (55 feet below ground surface).

The impacts of pilings on groundwater flow were considered. The installation of pilings can compress the surroundings soils, and the properties from soils below the [former] buildings have not been evaluated. However, they may be less transmissive, or may not be impacted at all. From the data collected, the dyes reached monitoring well MW-203A within two weeks of introduction to the sump area, suggesting the pilings are not retarding groundwater flow. It should also be noted that the sump was likely installed toward the southern end of the piling, so flow path/velocities would be less retarded. Because the dye study has produced the anticipated results, an evaluation of the soil and aquifer properties between the pilings is not warranted.

Based on the preliminary numerical model, tritium would take approximately 100 days to reach the Mississippi River and would occur at diluted concentrations, likely well below the Maximum Concentration Limit (MCL) of 20,000 pCi/L, as the levels of tritium measured in MW-202A (and its

Enclosure 1 to LC-2018-0075 Page 9 of 26 replacement MW-202AR), upgradient of the river, have been below 20,000 pCi/l. The following presents a summary of the preliminary modelling assumptions and parameters. The final calibration is currently planned to be completed by the end of August.

Input assumptions:

- Groundwater gradient across the site is approximately 0.002 feet per feet ft/ft, with groundwater flow towards the river, roughly due west.

- Effective porosity is 0.25

- The release is to the shallow aquifer only

- Three nearby supply wells are operating intermittently. These three wells have pumping rates of 120, 150, and 300 gallons per minute (GPM) and screens open from 120 ft below ground surface (bgs) to the water table. There is uncertainty to the actual well construction, but the shortest flow path to the well pump will be through the well pack, so it is conservative to assume the filter pack extends to the shallow groundwater.

- On average the wells are pumping less than 20% of the time, based on total flows. To be conservative with the well capture zones, we assume they are operating at maximum flow, 100% of the time.

- The release is on the order of 300 ft from the Mississippi River MODFLOW Model

- The Numerical model is divided up into six layers: shallow, a thin confining unit, two intermediate layers, and two deep layers

• Hydraulic conductivity in the shallow layers is 350 ft/d, estimated from slug testing in shallow monitoring wells

• Confining layer of silt or clay approximately 1 ft thick or less and encountered between 20 to 25 ft bgs in boring logs. There is uncertainty if this layer is continuous across the site, so it is modeled as a finer sand, with a K of 35 ft/d

• The intermediate layers have a K of 450 ft/d, estimated from slug testing in deep monitoring wells.

• Deeper layers are modeled with a hydraulic conductivity of 1000 ft/d (estimated from drillers logs.

• Anisotropy of 5 to 1: horizontal to vertical

- Grid spacing of 10 ft is used (see figure below)

- Model is run in steady state mode

- Porosity of 0.25

- Particles were released in the shallow layer to show groundwater flow paths.

- Mississippi river is the downgradient boundary condition, held at elevation 625 ft

- About 600 ft upgradient is a constant head boundary condition, estimated with monitoring well data, at elevation 627.50 ft

Enclosure 1 to LC-2018-0075 Page 10 of 26 The locations selected for the sorbent pads along the river were not specified in the investigation plan.

Because the river stage exerts local control over the groundwater level and flow pathways, the selection of boundary conditions on the western side of the site is important. The uncertainty of the boundary conditions on the eastern side may also be important for the flow model fidelity.

The intent of the dye study was to use a minimal amount of dye to that it would not be visible along the shoreline. One carbon sampling packet was secured along the river edge along the project pathway of the plume, however that data point is not critical to the models calibration. The predicted pathway from the preliminary model is presented below. Please note that for the preliminary model, the area of the source area is larger than the actual sump, resulting in a wider plume area.

Enclosure 1 to LC-2018-0075 Page 11 of 26 Provide the following information regarding potential impacts as a result of the unintended release:

7) Provide the possible exposure pathways for the material released.

LACBWR Response:

As noted above, there is minimal vertical flow to deeper zones within the aquifer, and no tritium has been detected above background concentrations at the supply well #5. There is no exposure to human health. Some tritium was likely discharged to the river; however, it expected to be at concentrations well below the MCLs, based upon the observed tritium levels in MW-202A/AR located upgradient of the river. Therefore, there are no unacceptable risks to the benthic or aquatic receptors. A more detailed ecological risk assessment will be part of the Site Investigation Report.

8) If a dose assessment was conducted, provide the results.

LACBWR Response:

A preliminary dose assessment, using the dose factors from the LTP, was performed to estimate the tritium concentrations corresponding to the EPAs safe drinking water standard of 4 mrem/yr. The estimated concentration corresponding to 4 mrem/yr dose was found to be approximately 190,000 pCi/lfar greater than the levels observed to date in the monitoring wells.

Provide the following information regarding monitoring and remedial actions related to the unintended release:

9) Explain if there is a plume of radioactive contaminants in the shallow (lower and upper portions) or deep aquifer. If so, how is it being monitored?

LACBWR Response:

Following the release of the impacted ice/snow melt into the excavated area, a tritium plume was created in the shallow aquifer. Conditions have been monitored using the existing groundwater monitoring well network by sample collection and analysis, following the discovery of impacted groundwater during the December 2017 sampling event. Samples were collected in February, April, June, and July of this year and will continue to be collected on an approximately monthly basis to further assess the site conditions. The results will be communicated to the NRC. To date, sampling and analysis has not identified any detectable contamination in wells located in the deeper aquifer.

10) Provide all sampling results for all ground water wells taken since 2012.

LACBWR Response:

See attachments. Note that data related to groundwater sampling is available beginning June of 2013.

Enclosure 1 to LC-2018-0075 Page 12 of 26

11) Describe corrective actions taken in response to the identified release and/or any future actions to be taken.

LACBWR Response:

Following the discovery of the impacted ice/snow melt containing tritium, the Reactor Building exhaust ventilation vents have been redirected away from the ground, and impoundments have been created below the operating exhaust ventilation units to collect storm water/surface water, and water collected is disposed of via monitored waste discharge streams. This adverse condition was entered into the corrective action program (CAP). The corrective actions will be documented in the CAP and in the site investigation report and the remedial actions taken.

12) Explain how Solutions is preventing or mitigating future releases as a result of this unplanned release.

LACBWR Response:

Actions to prevent/mitigate future release are discussed in the response to Item #11. A lessons learned will be documented in the company database and shared with the industry to ensure this does not occur at other sites undergoing decommissioning.

Additional follow-up information:

A. Item 6) Continued The RAI response indicates that the FSS will provide additional data for other radionuclides, and possibly tritium; though the text is not clear on the latter. If the FSS is being used to identify possible tritium contamination, clarify how soil samples and gamma scans will accomplish this; i.e.,

consideration that tritium is a beta emitter and nonsorbing radionuclide that readily partitions into the vapor phase. In addition, will any wet/dry swipes be taken and analyzed via liquid scintillation to identify possible tritium or other weak beta emitter contamination on surfaces, particularly concrete.

LACBWR Response:

Solutions has committed to additional sampling and analyses for the full suite of initial radionuclides, including tritium, in multiple locations directly associated with the area of concern. These locations include:

- Seven (7) locations within the area containing the RPGPA sump and eastern portion of the Turbine Building. Additionally, if levels of residual radioactivity in an individual sample exceed a SOF of 0.1 for gamma emitting radionuclides, then the sample(s) will be analyzed for HTD radionuclides.

- Eight (8) vertical boring locations will be performed around the perimeter of the Reactor Building foundation. Borings will be performed and samples collected at approximately one meter depths. Vertical borings will be performed to at least two meters in depth. Four (4) angled boring locations will be performed at four locations around the perimeter of the Reactor Building. Borings will be performed and samples collected at approximately one meter depths. Each one meter sample will be mixed and analyzed. Angled borings will be

Enclosure 1 to LC-2018-0075 Page 13 of 26 performed to at least two meters in depth once a calculated depth of 22 (elevation 614) is reached. The minimum number of samples to be collected and analyzed for the full suite of HTDs during this iteration is four (4). This represents a minimum of ten percent of all samples taken and a minimum of one sample beyond the 10% minimum will be selected at random. Additionally, if levels of residual radioactivity in an individual sample exceed a SOF of 0.1 for gamma emitting radionuclides, then the sample(s) will be analyzed for HTD radionuclides.

- Six (6) systematic locations will be subjected to concrete boring sampling into the base of the Reactor Bowl. At a minimum four additional cores will be collected at the identified locations during the scanning of the bowl during the Radiological Assessment survey. A minimum of 10 total samples will be collected. Ten percent of all samples taken will be sent off-site for the full suite of HTD analyses. In addition, a minimum of one sample beyond the 10%

minimum will be selected at random, also for HTD analysis. Additionally, if levels of residual radioactivity in an individual sample exceed a SOF of 0.1 for gamma emitting radionuclides, then the sample(s) will be analyzed for HTD radionuclides. This results in a minimum of two (2) samples sent offsite for analysis of the full suite of HTD radionuclides.

B. NRC Question 4 stated Describe whether the demolition activities mobilized radionuclides of concern other than tritium. The licensees response did not fully address this. The response states that there is potential to mobilize contamination from concrete to soil and further states:

Although the site takes precautionary measures to prevent this, the continuing characterization and/or subsequent FSS is designed to assume there could be a change to the established surrogate ratios for the HTD ROC. Ideally, the response would have included more details regarding the reasons why radionuclides are unlikely to be mobilized or the precautionary measures that the licensee takes to minimize the chances of mobilizing other radionuclides.

LACBWR Response:

The interior demolition of the Reactor Building was performed with an exterior containment structure and waste loadout cell. All interior demolition activities were performed under negative HEPA ventilation of the Reactor Building and associated containment and waste loadout structures to minimize airborne particulate migration from the areas until the structure was surveyed and deemed acceptable for demolition. The HEPA ventilation was sampled during operations to monitor for air quality and HEPA filter performance. The vast majority of the demolition materials were loaded while the containment tents were present. Remaining elevated materials within the containment tent footprint have been covered with steel plates to prevent spread of materials during demolition. Additionally, corrective actions have been implemented to reduce the potential for contamination migration. These includes over excavating the surfaces beside or beneath the concrete that was removed to a minimum of one bucket depth. The soils are disposed or sifted to remove any concrete that may have been pushed through the surface while hammering or processing concrete. Materials may only be placed back in the excavation if surveyed by a FSS technician.

C. For most survey areas only two samples are going to be analyzed for the full initial suite to compare the actual insignificant contribution (IC) to the assumed 10 percent, or compared to

Enclosure 1 to LC-2018-0075 Page 14 of 26 verify the surrogate ratios. The trigger for additional sampling is whether the actual IC dose is greater than 10%. What if some contamination is identified but the actual IC dose is still less than 10% or the surrogate ratio is not exceeded. Should the licensee consider how to determine the extent of contamination and find the size of the elevated area? How will the licensee know they have properly found the extent of contamination or bounded an elevated area if they dont take additional samples?

LACBWR Response:

As noted above, the trigger for collecting additional HTD samples is if the IC dose exceeds 10 percent of the total dose or if both Cs-137 and Sr-90 are detected and the surrogate ratio is greater than the applicable ratio from TSD RS-TD-313196-001. This is identical to the approach utilized at the Zion Decommissioning Project and we do not believe additional actions for investigating the extent of elevated areas below this criteria is warranted since the process is designed to accommodate the presence of residual radioactivity.

D. Finally, the licensee states that the actual IC dose will be calculated for each individual sample.

The licensee should verify how the concentration is calculated for each individual sample. For example, when collecting 6 inch cores that are divided into 1/2 inch pucks and each puck is analyzed for a concentration for the full initial suite of radionuclides, clarify that each individual concentration would be compared to the Base Case DCGLs to determine the actual IC dose as opposed to some average concentration over the entire core.

LACBWR Response:

The actual dose will be calculated for each individual sample result using the DCGLs from RS-TD-313196-004, Table 4 for soils and Table 35 for basement structures. The IC dose fraction will be calculated in accordance with Equation 5 of RS-TD-31316-001 for reported radionuclides.

The conversion of concrete core concentration in pCi/g to surface activity units in pCi/m2 is detailed in RS-TD-313196-001. The conversion factor and equation used in RS-TD-313196-001 follows:

pCi cm2 g 2.98x104 = 1 1.27cm 1m2 1x104 2 2.35 3 g m cm The process for the 6 inch cores from the Reactor Building is as follows:

Six systematic locations will be triangulated into the base of the Reactor Bowl. At a minimum four additional cores will be collected at locations during the Radiological Assessment beta-gamma survey. If no areas of elevated activity are identified during the scan, then the four core samples will be obtained at biased locations such as low points, cracks, or areas of discoloration.

Enclosure 1 to LC-2018-0075 Page 15 of 26 Cores will be obtained using a concrete core bit to a depth of 6 inches or until refusal encountered. The cores will be sectioned into 1/2 inch thick pucks. The pucks will be weighed and counted on both sides (top and bottom) using the on-site gamma spectroscopy system with the count time adjusted to achieve a MDC of less than 2.0 pCi/g for Cs-137. If activity is detected at a concentration greater than MDC in the puck representing the first 1/2 inch of concrete, the puck representing the second 1/2 inch of concrete will be analyzed. Subsequent pucks that represent concrete at deeper depths will be analyzed if the puck representing the concrete above is greater than MDC.

Ten percent of all samples taken will be sent off-site for the full suite of HTD analyses. In addition, a minimum of one sample beyond the 10% minimum will be selected at random, also for HTD analysis. Additionally, if levels of residual radioactivity in an individual sample exceed a SOF of 0.1, then the sample(s) will be analyzed for HTD radionuclides. These samples are anticipated to be the top 1/2 inch pucks from the sample locations. Additional pucks from a location may exceed a SOF of 0.1 at deeper depths and would also be sent offsite for the full suite of HTD analysis.

Each sample (puck) sent offsite for HTD analysis will have the IC dose fraction calculated as detailed above. If multiple pucks from one sampling location are sent offsite for HTD analysis, the activities would be summed through the conversion factor presented above to calculate the total activity for the depths in pCi/m2.

E. The following paragraph of the LTP copied from Section 5.2.9 is on surrogate ratios. This paragraph is somewhat ambiguous. Is the licensee proposing to use area specific ratios that are potentially less than the values in Table 5-11, or are they only proposing to use area-specific ratios that are higher than the values in 5-11?

The NRC staff does not agree that area-specific surrogate ratios which are less than the values in Table 5-11 should be permitted. (This would essentially give the licensee the pre-approval to use any ratio based on a single sample with positive results for Sr-90 and Cs-137 and is therefore not appropriately bounded.)

Any future continuing characterization or FSS data that contains positive results for Sr-90 will be reviewed. In these cases, the area specific ratios as determined by actual survey data will be used in lieu of the maximum ratios presented in Table 5-11. The area-specific ratios used and the survey data serving as the basis for the ratios will be documented in the release record for the survey unit. If the derived HTD to surrogate ratio is less than the applicable HTD to surrogate ratio from TSD RS-TD-313196-001, Table 40, then no further action is required.

LACBWR Response:

Solutions does not intend to utilize a Sr-90 to Cs-137 surrogate ratio that is less than the ratios presented in Table 5-11.

Enclosure 1 to LC-2018-0075 Page 16 of 26 NRC Follow-Up Information from September 19, 2018, Call with La Crosse Below are some bullets of topics written down when reading the response Enviro-26 RAI. The bullets are related to the supporting basis for the tritium concentration value that will be assigned in the dose assessment in the LTP. Beyond the first bullet, the intent of listing the other bullets is not to have LaCrosseSolutions address each one down the line. Depending on the method LaCrosseSolutions uses to estimate the tritium value input for dose assessment, some of the bullets more be more important and others may not be significantly relevant.

• The original request was to provide a supporting basis for the maximum value of tritium (anywhere) in the groundwater system, which would be the tritium value submitted for the dose assessment analysis. The highest tritium concentration in the groundwater is not necessarily the maximum concentration recorded in an existing well. One of the limitations of assessing groundwater conditions for decommissioning is that samples cannot be easily obtained from any location, as compared to scanning and sampling on the ground surface. The response to RAI Enviro-26 provides some good information, but I could not discern the approach in the RAI response that LaCrosseSolutions was taking to answering the question above.

LACBWR Response:

To address what the theoretical or estimated maximum concentration of tritium in groundwater could be, a numerical groundwater flow model was constructed to determine and verify groundwater flow pathways and velocities to better assess the potential release volume and concentration. The model was developed using site hydraulic conductivity estimates, geology interpreted from boring logs, pumping rates in production wells (assumed based on usage), water levels observed in monitoring wells, and calibrated with the results of the tracer test. The details of the numerical model, input parameters and assumptions for the model are provided in Attachment A.

The model was calibrated to estimate the magnitude and arrival time of tracer in the downgradient well with a release area of roughly 15 ft x15 ft, with 20,000 ug/L of tracer, using the assumed hydraulic conductivities and boundary conditions. The outputs were then used to estimate the total volume/concentration of tritium first introduced to the aquifer via the sump.

The groundwater model is only able to estimate possible release concentration and volumes, due to inherent non-uniqueness in modeling and some uncertainty in the timing and amount (i.e. volume and concentration) of the initial release. Because we do not know the exact duration of the release of condensate to the ground, nor the volume of stormwater runoff that migrated to the RPGPA sump area, based on conservative estimates, the model predicted that approximately 46,000 gallons of 60,000 pCi/L impacted groundwater could have resulted in concentrations observed in the monitoring wells. This volume would include storm water collection over approximately two months (including snow melt). Once in the RPGPA sump area, the tritium was in hydraulic communication with the shallow aquifer and the plume migrated towards the river.

Production wells showed no signs of drawing the plume downwards into deeper units, which is consistent with groundwater sampling. The plume traveled to the downgradient wells with a velocity

Enclosure 1 to LC-2018-0075 Page 17 of 26 consistent with estimates from the tracer test and hydraulic gradients/conductivities on the order of 3 ft/d.

• Fundamentally, three processes will lead to the change in tritium concentration between that measured in the ponded surface water and that measured in MW-203A: (i) the initial dilution from the volumetric flux of the (horizontally flowing) groundwater at the sump; i.e., the relationship of the mass flux of tritiated water that infiltrates at the sump and the (horizontal) groundwater flux (this may consider the possibility of non-uniform (temporal) flux of the contaminated water reaching the sump);

(ii) center of the tracer plume uncertainty - if offset from the centerline, then what is the transverse dispersion; and (iii) longitudinal dispersion between the area below the sump and MW-203A.

LACBWR Response:

Please see the response above and details of our model overview in Attachment A.

• The response to RAI Enviro-26 indicates that MW-203A is believed to be directly downgradient of the sump. What is the support for this assumption, given the comments in several bullets below pertaining to the water level data?

LACBWR Response:

Based on groundwater contours and the numerical model for varying river stages, MW-203A is located downgradient. This was confirmed by the dye tracer study as well as the results of the groundwater model. There may be slight variations on flow direction as influenced by river water levels, but the ultimate groundwater receptor is the Mississippi River.

• The gradient imposed on the numerical model is 0.002, based on the assignment of constant head boundary conditions of (i) 627.5 ft msl at the upgradient edge of the model domain (600 ft to the east), and (ii) 625 ft msl for the river stage. The source of these boundary condition values is not stated. Are they considered representative, based on judgement, or are they based on data collected during the tracer test?

o The range of gradients presented in the LTP are 0.004 to 0.005; is there a reason why a gradient of 0.002 was imposed in the model for the tracer test?

o Are the boundary conditions representative of conditions during the tracer test?

o Are those boundary conditions representative of the condition during the tritium release, considering the effect of the river on the flow system?

LACBWR Response:

As the modeling was completed at the same time as the tracer tests, we modeled the current conditions and feel that we have a conservative estimate of concentration and flow direction/velocity, as calibrated by the dye tracer study. The river stage will alter flow directions slightly as well as the gradients (i.e. higher river stage will result in smaller hydraulic gradients across the site), but the ultimate flow direction and discharge will still be the River.

Enclosure 1 to LC-2018-0075 Page 18 of 26

• The LTP states that the river stage strongly influences the flow beneath the site, particularly on the western portion of the site. The river stage is the most readily obtainable groundwater level data point; however, river stage data does not seem to be provided. In a previous telephone call, Haley &

Aldrich staff indicated that a minimum and maximum river stage would be used to assess uncertainty.

o River stage data from the dam (downstream side) is useful to represent variability, but may have uncertainty if applied to the site due to (i) river gradient between the dam and LACBWR, and (ii) the daily variability (>1 ft over a day) versus correspondence with timing of monitoring well data collection.

LACBWR Response:

Agreed. The river stage can directly impact the gradient and flow rates, however; the tritium release has been conservatively estimated with the higher gradients so that we could conservatively predict when the tritium could reach the River.

Additionally, the source has been eliminated and the data confirm that the initial peak concentrations of tritium (and dye) have already passed monitoring well MW-203A. As expected, there is a continued downward trend in concentrations and we continue to collect data that demonstrates groundwater flows towards the Mississippi River through relatively transmissive soils. There is some uncertainty, but both tritium and dye sample results show a downward trend that is consistent with the conceptual site model (CSM).

• Groundwater level data from 2012 through 2016 exhibit gradient reversals, and possibly flattening of the water table in a portion of the site relevant to the tritium migration. It should be noted, however, that figures in the LTP and cited literature show contours that may include a bit too much artistic license based on the sparsity of the wells (for defining flow directions at the scale area of the primary buildings).

o Given the influence of the river on flow at the site, particularly in the western portion of the site, how do the prescribed boundary conditions in the model reflect the hydrologic conditions during the tracer test as compared to those during the months of the tritium release?

o For example, where would the tritium go if the river stage is higher than the groundwater levels on the western side of the site? In this situation, there is not likely a direct and nearly perpendicular flow path to the river. Certainly, when river stage is lower than groundwater levels in the closest monitoring levels, there is no swale in the groundwater potentiometric surface between the river and the area below the plant buildings.

o In addition, there is no information on the time length scale for the response of the groundwater levels to changes in river stage.

LACBWR Response:

See response provided above. We have not measured the lag time/response to groundwater and the river stage but based on the overall size of the site and historic impacts, we feel that the existing monitoring well network adequately characterized the shallow groundwater. Additional wells could be installed, and transducers could be placed along the shoreline and in the river to further document the hydraulic communication, however, it would not change the conclusion of a limited release of tritium to the aquifer. The source has been removed, the concentrations are decreasing, and are currently below the EPA MCLs.

Enclosure 1 to LC-2018-0075 Page 19 of 26

• The effect of compaction from the buildings and pilings on permeability was mentioned in the LTP, but discounted in the Enviro-26 RAI response solely because tracer was observed in MW-203A. Was the tracer concentration level in the well consistent with an expected magnitude of tracer (and why)?

Are there alternative explanations for the recorded tracer concentration levels in the well?

LACBWR Response:

The dye tracer results were as anticipated, confirming our CSM. Based on these results, piles present below the former sump and Turbine Building did not adversely impact or restrict groundwater flow.

• What is the objective of the numerical model? The response for RAI Enviro-26 states the purpose is to predict flow pathways and velocity and a dye tracer test to confirm the source area and to calibrate the model. Will the numerical model be used to estimate peak tritium concentrations in the groundwater, noting the bullet below on dilution processes starting with the concentration in the surface ponded water?

LACBWR Response:

The numerical model was used to further evaluate groundwater flow and to predict tritium concentrations and flow paths. It was completed in response to the Site Investigation required by the Department of Natural Resources (DNR) to evaluate the impacts of tritium in groundwater, following this release.

• With the inclusion of potable water wells that tap deeper portions of the aquifer, it seems that an unstated objective of the numerical model is to demonstrate that tritium or tracer is not being pulled down to the deeper wells that provide potable water to the site.

LACBWR Response:

Agreed. DNR is also concerned about the potential for the dye RWT to reach the wells. Both the sample results and the model indicate there have been no impacts, nor are there any anticipated impacts to the deeper potable supply wells.

• What is the meaning of calibration of the model? The flow path and imposed boundary conditions prescribe the flow direction and flow rate. Also, how does the sampling reflect on calibrations. For example, tracer samples represent composites covering a duration of 1 week. A peak was apparently reached sometime between 1 and 2 weeks after tracer injection. The composite duration compared to the time to peak may reflect on the level of uncertainty.

LACBWR Response:

The numerical model was calibrated to current dye and tritium results as well as groundwater elevations. See Attachment A for more details on the modeling approach.

Enclosure 1 to LC-2018-0075 Page 20 of 26

• The flux of the tritium seeping into the groundwater system is not known, though the time frame is readily bounded. The flux of tritium is related to the precipitation, melting, and contribution area -

all of which leads to a non-uniform (and intermittent) flux to the sump. Climatic conditions could be used, but estimation of tritium flux into the sump would necessarily have to be rather conservative using this type of approach. Scenarios in a numerical model may be another approach, but groundwater conditions during the period of the tritium release need to be considered because of the variable flow rates and directions illustrated in the available monitoring well data. This was not stated in the RAI response for Enviro-26 as an objective of the model LACBWR Response:

See response to the first question as well as Attachment A.

Additional Dose Modeling Considerations

• NRC staff note that the potential groundwater dose from the radionuclides demarcated as insignificant contributors must also be accounted for in demonstrating compliance. Table 2-19 of the LTP shows the groundwater monitoring samples analyzed for the full initial suite in 2014. During the June 2014 sampling event, H-3 and Sr-90 were detected; C-14, Tc-99, Eu-152, Pu-239/240 and Am-241 were also positively detected at low concentrations in several wells.

During the September 2014 sampling, Co-60, Ni-63, Cs-137, Eu-152, Eu-154, Pu-239/240 and Am-241 were also positively detected at low concentrations in several wells in addition to Sr-

90. For those insignificant radionuclides positively detected in soil, concrete, or in groundwater, a dose should be estimated and assigned to them for groundwater.

LACBWR Response:

We believe that the positive detections shown from the 2014 sampling events are false positives, however, it is very unlikely that this hypothesis can be adequately confirmed for samples collected over 4 years ago. Therefore, in response to this observation and to address the NRC staff request, we performed a dose estimate for the positive detections.

The dose assessment performed here is identical to that provided in the LTP. Specifically, we have assumed that the ingestion dose factors from Federal Guidance Report 11 are applicable and that the annual water ingestion is 327 L. The ingestion dose conversion factors (ING DCF) for all of the nuclides shown in Table 2-19 of the LTP are provided in the following table.

Ingestion Dose Conversion Factors from FGR 11 ING Nuclide DCF, mrem/pCi H-3 6.40E-08 C-14 2.09E-06 Fe-55 6.07E-07

Enclosure 1 to LC-2018-0075 Page 21 of 26 ING Nuclide DCF, mrem/pCi Ni-59 2.10E-07 Co-60 2.69E-05 Ni-63 5.77E-07 Sr-90 1.42E-04 Nb-94 7.14E-06 Tc-99 1.46E-06 Cs-137 5.00E-05 Eu-152 6.48E-06 Eu-154 9.55E-06 Eu-155 1.53E-06 Pu-238 3.20E-03 Pu-239 3.54E-03 Pu-240 3.54E-03 Pu-241 6.85E-05 Am-241 3.64E-03 The concentrations for samples that were identified as positive in each sampling event is shown in the following tables (the bolded values from LTP Table 2-19). Also, the corresponding annual dose is shown at the bottom of each table without considering radioactive decay and assuming an annual water ingestion of 327 L.

As shown in these tables, the maximum dose from the identified positive detections in 2014 was 0.471 mrem/y from well MW-DW7 from the June 2014 sampling event from Pu-239 and no identified H-3. As noted by NRC staff, the total dose from groundwater that was assigned in LC-FS-TSD-002 Rev 01 was 3.25 mrem corresponding to a total dose fraction of 0.13 from groundwater that was used to develop the operational DCGLs as had been being applied for FSS activities at the site in recent months. This total dose can be reduced by 0.471 mrem to obtain a remaining dose from H-3 of 2.779 mrem which corresponds to a H-3 concentration of over 110,000 pCi/L. This concentration is significantly higher than the any observed H-3 concentration in groundwaters in MW-203 since Jan 2018. We therefore conclude that this analysis, coupled with the demonstration that we have reasonably bounded the maximum plume concentrations, confirms that the inclusion of the positive detections from 2014 results does not change the conservative assumption in FS-TSD-002 Rev 01 that the total groundwater dose from positive detections will not exceed the assigned dose of 3.25 mrem/yr.

Enclosure 1 to LC-2018-0075 Page 22 of 26 June 2014 Well Concentrations (pCi/L) for Radionuclides Identified as Positive and the Corresponding Dose (mrem/y)

MW- MW- MW- MW- MW- MW- MW- MW- MW- MW- MW- MW- MW- MW- MW- MW-MW-B2 MW-B3 Nuclide DW3 DW4 DW5 DW7 B11R B11AR 200-A 200-B 201-A 201-B 202-A 202-B 203-A 203-B 204-A 204-B H-3 2.45E+02 3.36E+02 2.79E+02 2.79E+02 C-14 1.30E+01 Fe-55 Ni-59 Co-60 Ni-63 Sr-90 1.12E+00 1.17E+00 2.01E+00 Nb-94 Tc-99 5.08E+00 6.95E+00 6.31E+00 Cs-137 Eu-152 9.48E+00 1.42E+01 9.71E+00 1.12E+01 1.08E+01 Eu-154 Eu-155 Pu-238 Pu-239 4.07E-01 Pu-240 Pu-241 1.72E-01 9.71E-01 1.16E-01 1.56E-01 Am-241 Dose, 2.01E-02 0.00E+00 0.00E+00 4.71E-01 5.13E-03 0.00E+00 0.00E+00 3.01E-02 2.44E-02 2.42E-02 0.00E+00 2.37E-02 6.18E-02 2.29E-02 6.03E-02 5.84E-03 1.00E-01 1.19E-02 mrem/y

Enclosure 1 to LC-2018-0075 Page 23 of 26 Sept 2014 Well Concentrations (pCi/L) for Radionuclides Identified as Positive and the Corresponding Dose (mrem/y)

MW- MW- MW- MW- MW- MW- MW- MW- MW- MW- MW- MW- MW-Radionuclide DW5 B11R B11AR 200-A 200-B 201-A 201-B 202-A 202-B 203-A 203-B 204-A 204-B H-3 C-14 Fe-55 Ni-59 Co-60 3.56E+00 3.67E+00 Ni-63 5.00E+00 Sr-90 1.14E+00 Nb-94 Tc-99 Cs-137 3.97E+00 2.17E+01 Eu-152 9.40E+00 Eu-154 4.18E+00 Eu-155 Pu-238 Pu-239 1.41E-01 Pu-240 Pu-241 2.29E-01 1.40E-01 2.51E-01 2.69E-01 Am-241 Dose, mrem/y 6.48E-02 0.00E+00 0.00E+00 4.39E-01 5.13E-03 4.08E-03 1.63E-01 1.99E-02 1.30E-02 3.79E-02 0.00E+00 0.00E+00 6.02E-03

Enclosure 1 to LC-2018-0075 Page 24 of 26

• One of the key assumptions in the licensees analysis is that the concentration of Sr-90 in relation to Cs-137 at any given location will be relatively small, and therefore due to the sum of fractions rule, only a small fraction of the Sr-90 DCGL will be allowed in comparison to the Cs-137 DCGL. The hypothetical maximum concentration which the licensee assumed for Sr-90 is limited by the mixture ratios, forcing the hypothetical maximum concentration to be 4.5 pCi/g, which is magnitudes of order below the derived concentration limit (5,297.4 pCi/g). Given that the safety evaluation associated with the LACBWR LTP will be approving DCGLs for each radionuclide following a sum of fractions approach, as opposed to limiting the individual fractions allowed for each radionuclide, the Sr-90 levels in the soil are bounded by the DCGL in the absence of all other radionuclides. The licensee should provide additional justification for why Sr-90 is not likely to be found in areas where Cs-137 is not present, or additional rationale for how the level of 4.5 pCi/g assumed by the licensee reflects the actual maximum concentration of Sr-90 that will be allowed to be left at the site at license termination LACBWR Response:

Sixty-two (62) soil/sediment samples have been collected since 2017 to support characterization, RASS, and FSS surveys for HTD analysis by a commercial offsite laboratory. The results of these analysis for Sr-90 and Cs-137 are provided in the table below. This Table shows the Laboratory Qualifier (Lab_Qual) for each result, and, in the case where there is no qualifier shown, the laboratory considered that the radionuclide was positively detected. Where no value is shown, the analysis for the applicable nuclide was not obtained.

As seen in this table, all results for Sr-90 were non-detected. For Cs-137, 13 of the 33 samples analyzed for Cs-137 were non-detected. This clearly demonstrates the absence of Sr-90 and the very low concentrations of Cs-137. Therefore, it is unlikely that an abundance of Sr-90, well above the alternate scenario DCGL, is expected at the site.

Sr-90Sr-90 Cs-137 Lab_Result/ Uncertainty, Lab_Result/ Uncertainty, Sample Type Sample_No pCi/g pCi/g Lab_Qual pCi/g pCi/g Lab_Qual Soil B1-010-04A-CJFS-001-SB 0.178 0.226 U 0.019 0.022 U Soil B1-010-04A-CJFS-002-SB 0.205 0.231 U 0.005 0.024 U Soil B1-010-04A-CJFS-003-SB 0.299 0.241 U -0.002 0.028 U Soil B1-010-04A-CJFS-004-SB 0.120 0.216 U 0.009 0.021 U Soil B1-010-04A-CJWS-005-SB -0.073 0.195 U 0.108 0.041 Soil B1-010-04A-CJWS-006-SB -0.088 0.187 U 0.034 0.054 U Soil B1-010-04A-CJWS-007-SB 0.210 0.209 U 0.076 0.043 Soil B1-010-04A-CJWS-008-SB -0.024 0.135 U 0.100 0.075 Soil B1-010-04A-QJWS-008-SB 0.136 0.277 U 0.117 0.064 Soil L1-010-101-FS-GS-C06-SB 0.149 0.182 U 0.503 0.088 Soil L1-010-101-FS-GS-C14-SB -0.098 0.167 U 1.270 0.117 Soil L1-PAD-Q01-AJGS-103-SS 0.126 0.218 U

Enclosure 1 to LC-2018-0075 Page 25 of 26 Sr-90Sr-90 Cs-137 Lab_Result/ Uncertainty, Lab_Result/ Uncertainty, Sample Type Sample_No pCi/g pCi/g Lab_Qual pCi/g pCi/g Lab_Qual Soil L1-PAD-Q01-AJGS-1101-SS -0.049 0.113 U Soil L1-PAD-Q01-AJGS-1303-SS -0.013 0.163 U Soil L1-PAD-Q01-AJGS-1603-SS 0.220 0.199 U Soil L1-PAD-Q01-AJGS-1703-SS 0.021 0.115 U Soil L1-PAD-Q01-AJGS-1803-SS -0.215 0.304 U Soil L1-PAD-Q01-AJGS-2002-SS 0.051 0.155 U Soil L1-PAD-Q01-AJGS-501-SS 0.050 0.200 U Soil L1-PAD-Q01-AJGS-701-SS 0.089 0.175 U Soil L1-PAD-Q01-AJGS-803-SS 0.038 0.151 U Soil L1-PAD-Q01-AJGS-901-SS -0.024 0.122 U Soil L1-PAD-Q02-AJGS-1103-SS 0.125 0.148 U Soil L1-PAD-Q02-AJGS-1401-SS 0.050 0.129 U Soil L1-PAD-Q02-AJGS-1501-SS -0.056 0.087 U Soil L1-PAD-Q02-AJGS-401-SS 0.063 0.206 U Soil L1-PAD-Q02-AJGS-601-SS 0.163 0.158 U Soil L1-PAD-Q03-AJGS-1002-SS -0.010 0.277 U Soil L1-PAD-Q03-AJGS-1201-SS 0.143 0.195 U Soil L1-PAD-Q03-AJGS-1902-SS 0.037 0.154 U Soil L1-PAD-Q03-AJGS-201-SS -0.178 0.469 U Soil L1-PAD-Q03-AJGS-303-SS -0.019 0.189 U Soil L1-SUB-DRS-FSGS-W12-SB -0.022 0.076 U Soil L1-SUB-DRS-FSGS-W14-SB 0.103 0.092 U Soil L1-SUB-LES-FSGS-001-SB 0.036 0.093 U Soil L1-SUB-LES-FSGS-012-SB 0.115 0.110 U Soil L1-SUB-TDS-FJGS-003-SB 0.062 0.122 U 0.165 0.064 Soil L1-SUB-TDS-FJGS-004-SB 0.023 0.178 U 0.103 0.041 Soil L1-SUB-TDS-FJGS-005-SB -0.037 0.155 U 0.107 0.038 Soil L1-SUB-TDS-FJGS-006-SB -0.140 0.258 U 0.189 0.047 Soil L1-SUB-TDS-FJGS-007-SB 0.014 0.117 U 0.038 0.026 U Soil L1-SUB-TDS-FJGS-008-SB 0.113 0.183 U 0.072 0.033 Soil L1-SUB-TDS-FJGS-010-SB -0.050 0.132 U 0.056 0.031 Soil L1-SUB-TDS-FSGS-010-SB 0.206 0.172 U Asphalt L2-SUB-102-AJGS-001-AV -0.003 0.199 U 0.003 0.031 U Soil L2-SUB-102-AJGS-001-SS -0.190 0.179 U 0.000 0.040 UI

Enclosure 1 to LC-2018-0075 Page 26 of 26 Sr-90Sr-90 Cs-137 Lab_Result/ Uncertainty, Lab_Result/ Uncertainty, Sample Type Sample_No pCi/g pCi/g Lab_Qual pCi/g pCi/g Lab_Qual Soil L2-SUB-102-AJGS-019-SB -0.023 0.213 U 0.045 0.037 U Soil L2-SUB-102-AJGS-024-SB -0.223 0.162 U 0.015 0.077 U Soil L2-SUB-103-AJGS-002-SB 0.154 0.349 U 0.001 0.114 UI Soil L2-SUB-VAR-AJGS-004-SB -0.191 0.177 U 0.369 0.079 Soil L2-SUB-WRS-AJGS-15A-SB -0.070 0.123 U 0.187 0.076 Soil L2-SUB-WRS-ASGS-10A-SB -0.008 0.307 U 0.175 0.130 U Soil L3-012-102-FSGS-004-SG 0.090 0.207 U Soil L3-012-102-FSGS-008-SS 0.014 0.198 U Soil L3-012-102-FSGS-009-SS -0.056 0.174 U Soil L4-OFF-SOL-AJGS-B01-SB 0.113 0.210 U -0.011 0.036 U Soil LI-SUB-CDR-FSGS-008-SB 0.248 0.180 U 0.804 0.115 Soil LI-SUB-CDR-FSGS-009-SB -0.178 0.133 U 11.5 0.274 Soil LI-SUB-CDR-FSGS-011-SB 0.079 0.141 U 3.77 0.234 Soil LI-SUB-CDR-FSGS-012-SB 0.163 0.193 U 2.21 0.168 Soil LI-SUB-CDR-FSGS-014-SB 0.080 0.159 U 2.77 0.213 Sediment S1-102-CWD-FIFS-A02-SM -0.023 0.216 U 8.230 0.306 Additional Dose Modeling Considerations

• Check Section 6.20.1 of the LTP for a typo regarding when to measure for HTDs.

LACBWR Response:

The typo in LTP Section 6.20.1 is being corrected.

• Section 6.5.2 of the LTP, Rev. 1, states that the licensee would notify the NRC if they encounter contamination greater than 1m below surface and need to perform additional dose modeling. NRC staff note that in this event, the following change criteria would be triggered and the NRC would need to review and approve the additional dose modeling.

o Change the approach used to demonstrate compliance with the dose criteria (e.g.,

change from demonstrating compliance using derived concentration levels to demonstrating compliance using a dose assessment that is based on final concentration data).

LACBWR Response:

The LACBWR LTP Section 6.5.2 is being revised to indicate that NRC approval must be sought.

Attachment A to Enclosure 1 to LC-2018-0075 Page 1 of 6 INTRODUCTION AND OBJECTIVE A numerical model was constructed with the following purposes:

To determine overall site groundwater flow pathways and velocities at the site, using existing hydraulic head data and boring logs To estimate the effect of nearby domestic pumping wells on gradients and groundwater flow paths. Three domestic pumping wells are present within the sites boundaries and may influence shallow groundwater flow.

To estimate the contaminant transport and travel times from the release of tritium impacted water to the Mississippi River, approximately 300 feet downgradient, using the flow model and the results of a tracer test performed with dye.

To assess possible tritium release size and concentration, and the concentration of tritium in groundwater as it would enter the Mississippi River.

METHODS Analytical calculations are used; the Darcy flux and contaminant velocity are estimated to guide the numerical modeling assumptions and compare with the results.

Numerical groundwater flow modeling with MODFLOW (Groundwater Vistas) is used to estimate the contaminant transport. The MT3D package was used to simulate contaminant flow, no degradation is assumed, and releases are based on initial conditions. The version used was MODFLOW2005 The MODFLOW model was calibrated with hydraulic heads observed across the site to establish a base flow system used in the transport modeling. The MODFLOW model was calibrated with data assuming it was at a steady state condition. The first timestep of the model was steady state, with subsequent timesteps used for estimating contaminant transport velocity.

The MT3D model was compared with the concentrations observed in the tracer test and from the tritium release. The tracer test was used to further understand contaminant velocity at the site, and the tritium release data was used to estimate a possible source volume and concentration of tritium in the initial release. MT3D was run using the results of the steady state and the transient MODFLOW model, with an initial condition of a steady state flow field.

ASSUMPTIONS Assumptions for the model are based on previously completed hydrogeologic investigations onsite and the conceptual site model. Because of the limited calibration information (only a few hydraulic head points, and limited concentrations observed in monitoring wells), and limited knowledge of the original release and groundwater flow during the original release, a simplified conceptual model of the geology was used. A review of available boring logs, well completion details, and available hydrogeologic information were used to make the following assumptions:

Hydraulic conductivity generally increases with depth. This is consistent with drillers logs from the domestic wells (simple soil descriptions), and hydraulic conductivity testing in the H&A well clusters.

The Numerical model is divided up into six layers: shallow, a thin confining unit, two intermediate layers, and two deep layers.

- Hydraulic conductivity in the shallow layers is 350 ft/d (estimated from slug testing in shallow HA wells).

Attachment A to Enclosure 1 to LC-2018-0075 Page 2 of 6

- Confining layer of silt or clay approximately 1 ft thick or less is encountered between 20 to 25 ft bgs based on boring logs. There is uncertainty if this layer is continuous across the site, so it is modeled as a finer sand, with a K of 35 ft/d.

- The intermediate layers have a K of 450 ft/d (estimated from slug testing in deep HA wells).

- Deep layers are modeled with a hydraulic conductivity of 1000 ft/d (estimated from drillers logs.

- Anisotropy of 5 to 1 (horizontal to vertical).

Figure 1: Screenshot of the contaminant transport model, with the river and upgradient boundary conditions, and the model grid Groundwater gradient across the site is approximately 0.002 ft/ft, with groundwater flow towards the river, roughly due West. This is a conservative estimate made from the hydraulic head observations.

Effective porosity used in the MT3D transport model is 0.25, and is a typical value and is used for sands which underlay the site. There is no assumed retardation or breakdown of tritium, which is conservative (for worst-case, which is higher concentrations reaching the river). Similarly, dispersity and diffusion parameters of 0 are assumed, which will yield the greatest concentration when reaching the river.

Attachment A to Enclosure 1 to LC-2018-0075 Page 3 of 6 The releases of tritium and the tracer are to the shallow aquifer only, based on the excavations and works that released the tritium. The timing of the tritium release was assumed to be mid-November of 2017.

The three domestic supply wells are operating intermittently. According to boring logs and information from owners, the three wells have pumping rates of 120, 150, and 300 GPM, and screens open from 120 ft bgs to the water table. There is uncertainty to the actual well construction with the filter pack due to the logs being incomplete. The shortest flow path to the well pump will be through the well pack, so it is conservative from a contaminant transport perspective to assume the filter pack extends to the shallow groundwater. On average the wells are on less than 20% of the time, based on the total flows. To be conservative with the well capture zones, we assume they are operating at maximum flow, 100% of the time, which is conservative for assessing their capture of tritium.

The release volume and extent are not precisely known, but it is on the order of 300 ft from the Mississippi River. The release will be estimated from the MT3D modeling.

ANALYTICAL CALCULATIONS The groundwater flow velocity and Darcy flux can be estimated from the gradient, effective porosity, and hydraulic conductivity (K).

- Gradient = 0.002 ft/ft

- K = 350 ft/d

- Resulting Flux = 0.7 ft/d Dividing by porosity yields 2.8 ft/d for the groundwater flow velocity. Assuming no retardation (consistent with tritium), the contaminant transport velocity will be the groundwater flow velocity. Therefore, groundwater from the release could travel to the Mississippi River on the order of 100 days from the release.

MODFLOW MODEL Model is run in steady state mode first, to calibrate to the steady state water level data. Transport modeling was run in transient mode with 100 timesteps, each representing one day of transport.

Grid spacing of 10 ft is used, total number of grid cells was 206724.

Particles were released in the shallow layer to show groundwater flow paths and estimate initial travel times, to confirm the analytical modeling results and estimate travel times.

The three domestic supply wells showed no influence on any particles released in the shallow aquifers. The more transmissive deeper units and long well screens make the capture zones of the domestic wells limited to the deeper units in the steady state model runs.

TRACER TEST MODEL The tracer test was modeled by releasing a slug of tracer in an approximately 15 ft x 15 ft grid in the shallow layer. This is consistent with the size of the open pit where the tracer was mixed.

The tracer test model was performed several months after the initial tritium release, and the groundwater head and river stage were different. The pit in which the tracer was mixed was not identical to the initial tritium release, and therefore the dye test was used as a confirmation, to understand the groundwater flow system.

Based on the initial concentration of dye, volume of flush water administered, and existing standing water in the sump excavation, the tracer concentration entering the groundwater was estimated at approximately 20,000 ug/L. Based on the results observed at MW-203A, this

Attachment A to Enclosure 1 to LC-2018-0075 Page 4 of 6 matches the timing and magnitude predicted or estimated by the groundwater model. MW203A was the only well to observe any tracer concentrations at the site.

The tracer test confirms that the groundwater velocities in the MODFLOW model can imitate the contaminant transport flow paths observed at the site.

Figure 2: Groundwater flow paths as predicted by the MODFLOW model, from the approximate release area to the Mississippi River downgradient boundary condition.

TRITIUM RELEASE MODEL The tritium concentrations observed in the shallow monitoring wells were used to estimate an initial release volume and concentration, and therefore be able to estimate the potential maximum concertation possible in groundwater.

An initial release date of 15 November 2017 was assumed based on elevated tritium concentrations detected in groundwater samples collected in early December and assessing prior activities completed onsite, including operation of the Torit system, and samples collected from the condensate that had collected below the ventilation.

To match the approximate arrival times and magnitudes of tritium to wells MW-201A and MW-202A, the amount of tritium impacted water and concentration of tritium required are approximately 46,000 gallons of 60,000 pCi/L. Based on the tritium release parameters and dilution volume from site rain fall (and possible snow melt) over this time, these calculations support the model results.

Attachment A to Enclosure 1 to LC-2018-0075 Page 5 of 6 Figure 3: The resulting plume of tritium in groundwater at 85 days after release, as predicted by the MODFLOW and MT3D models A less desirable concentration match for well MW-203A was found with these values, and the amount of tritium in the well was overestimated by approximately 35%. This is considered conservative, as the lower concentrations are probably due to preferential flow paths. No match for both wells could be found with the assumptions stated, so an over-estimate of concentration in the upgradient well is a conservative assumption.

Note: there is some uncertainty inherent in numerical modeling of this kind due to non-uniqueness. A different combination of release areas, volumes, concentrations and times could yield results like this estimate. More complex flowpaths, seasonal and other changes in water table and flow could affect the groundwater flow across the releases. The simplified model approach was taken to be conservative for the initial release of tritium, and its possible strength as it enters the river.

The pumping wells showed no signs of capturing the tritium release in the numerical model under any model run.

The tritium release occurred during the winter months (November 2017), where the stormwater was collected in the former sump and excavated to an elevation that was approximately 10 feet below the water table. The dye tracer test was approved in late June 2018, more than six months later, and after the former sump area had been filled with sediment to approximately three feet below the water table. These changes in site conditions may have contributed to the uncertainty of the model results.

Attachment A to Enclosure 1 to LC-2018-0075 Page 6 of 6 RESULTS The capture zone of all three wells pumping simultaneously at steady state does not encompass the reactor building or the release area. The influence of the three pumping wells is small, as the hydraulic conductivities of the deeper units are higher.

Groundwater flow velocity in the shallow unit is estimated to be on the order of 2.8 ft/d, this is consistent across observations from the tracer study, estimated tritium release date and concentrations in wells, and the numerical and analytical modeling. Resulting transport time to the Mississippi is on the order of 100 days.

The tracer test observations were close to those predicted by the numerical model, confirming the general groundwater flow direction and velocity.

The model was able to match the tritium concentrations in downgradient monitoring wells MW-201A and MW-202A with an initial release of approximately 46,000 gallons of 60,000 pCi/L impacted water back calculated and verified using the dye tracer calibration test. While these results did not translate as closely for MW-203A, we believe that is due to other preferential flow paths between the sump and MW-203A, or potential impacts from the underlying piles.

The maximum concentration in the center of the plume as it was reaching the Mississippi River was approximately 10,500 pCi/L. This has resulted in approximately 2 µg of tritium to be released to the river from the initial release through October 2018.

No dye has been detected in the river.

Domestic supply pumping wells showed no sign of capturing tritium under any modeling.

No tritium or dyes have been detected in the supply pumping wells.

Attachment B to Enclosure 1 to LC-2018-0075 Page 1 of 39 Location 3 3 3 3 3 4 Sample ID MW-DW3-06182014 MW-DW3-071018 MW-DW3-081518 MW-DW3-091018 MW-DW3-101018 MW-DW4-06182014 Sample Date 06/18/2014 7/10/2018 8/15/2018 9/10/2018 10/10/2018 06/18/2014 Radiological (pCi/L)

Americium-241 0.0539 +/- 0.0898 - - - - 0.0342 +/- 0.0901 Niobium-94 0.44 +/- 2.13 - - - - 0.143 +/- 1.98 Plutonium-238 0.0283 +/- 0.279 - - - - -0.0477 +/- 0.173 Plutonium-239/240 -0.0961 +/- 0.201 - - - - 0.0336 +/- 0.173 Plutonium-241 3.51 +/- 17.5 - - - - 2.7 +/- 20.1 Strontium-90 0.609 +/- 0.686 - 0.0845 U + 0.959 - -0.374 U + 0.688 0.0899 +/- 0.658 Technetium-99 -8.28 +/- 3.49 - - - - -7.37 +/- 3.52 Tritium 105 +/- 137 -99 U + 267 -347 U + 265 245 U + 317 55.4 U + 259 159 +/- 141 Notes:

R = Result is rejected

- = Analysis for radionuclide not performed pCi/L = picoCuries per liter U = Not detected, number is the laboratory reporting limit Reporting values exceed one or more of the regulatory criteria Duplicate analyses performed.

Attachment B to Enclosure 1 to LC-2018-0075 Page 2 of 39 Location 5 5 5 5 5 5 Sample ID MW-DW5-06182014 MW-DW5-09242014 DW-5-03252015 DW-5-11122015 Well 5-120716 Well-5-052217 Sample Date 06/18/2014 09/24/2014 03/25/2015 11/12/2015 12/07/2016 05/22/2017 Radiological (pCi/L)

Americium-241 0.00465 +/- 0.0846 0.128 +/- 0.156 - - - -

Niobium-94 -1.26 +/- 1.69 -0.945 +/- 2.04 1.86 +/- 2.15 -0.374 +/- 2.1 - -

Plutonium-238 -0.0222 +/- 0.155 0.0171 +/- 0.0714 - - - -

Plutonium-239/240 0.0313 +/- 0.161 0.0928 +/- 0.121 - - - -

Plutonium-241 -8.39 +/- 17.6 3.18 +/- 9.32 - - - -

Strontium-90 0.0899 +/- 0.595 -0.0174 +/- 0.657 -0.037 +/- 0.658 -0.58 +/- 0.907 0.870 U +/- 0.829 0.370 U +/- 0.696 Technetium-99 -8.26 +/- 3.48 -1.54 +/- 3.15 - - - -

Tritium 194 +/- 141 34.3 +/- 139 -52.6 +/- 144 -104 +/- 146 -96.7 U +/- 133 -8.03 U +/- 237 Notes:

R = Result is rejected

- = Analysis for radionuclide not performed pCi/L = picoCuries per liter U = Not detected, number is the laboratory reporting limit Reporting values exceed one or more of the regulatory criteria Duplicate analyses performed.

Attachment B to Enclosure 1 to LC-2018-0075 Page 3 of 39 Location 5 5 5 5 5 5 Sample ID Well-5-120717 Well-5-060618 Well-5-071018 Well-5-081518 Well-5-091118 Well-5-101018 Sample Date 12/07/2017 6/6/2018 7/10/2018 8/15/2018 9/11/2018 10/10/2018 Radiological (pCi/L)

Americium-241 - - - - - -

Niobium-94 - - - - - -

Plutonium-238 - - - - - -

Plutonium-239/240 - - - - - -

Plutonium-241 - - - - - -

Strontium-90 -0.25 U +/- 0.443 - - 0.691 U + 1.06 - -0.429 U + 0.771 Technetium-99 - - - - - -

Tritium -127 U +/- 330 -166 U +/- 226 1.44 U + 276 -97.8 U + 285 -62.9 U + 181 238 U + 273 Notes:

R = Result is rejected

- = Analysis for radionuclide not performed pCi/L = picoCuries per liter U = Not detected, number is the laboratory reporting limit Reporting values exceed one or more of the regulatory criteria Duplicate analyses performed.

Attachment B to Enclosure 1 to LC-2018-0075 Page 4 of 39 Location 7 7 7 7 7 7 Sample ID MW-DW7-06182014 Well-7-060618 Well-7-071018 Well-7-081518 Well-7-091118 Well-7-101018 Sample Date 06/18/2014 6/6/2018 7/10/2018 8/15/2018 9/11/2018 10/10/2018 Radiological (pCi/L)

Americium-241 -0.011 +/- 0.0766 - - - - -

Niobium-94 0.749 +/- 2.35 - - - - -

Plutonium-238 0.0822 +/- 0.169 - - - - -

Plutonium-239/240 0.407 +/- 0.332 - - - - -

Plutonium-241 2.62 +/- 13 - - - - -

Strontium-90 0.0178 +/- 0.726 - - 0.184 U + 0.860 - -0.98 U + 0.712 Technetium-99 -9.36 +/- 3.53 - - - - -

Tritium 123 +/- 139 124 U +/- 245 -49.3 U + 271 10.2 U + 289 -45.5 U + 189 45.6 U + 254 Notes:

R = Result is rejected

- = Analysis for radionuclide not performed pCi/L = picoCuries per liter U = Not detected, number is the laboratory reporting limit Reporting values exceed one or more of the regulatory criteria Duplicate analyses performed.

Attachment B to Enclosure 1 to LC-2018-0075 Page 5 of 39 Location B2 B3 B11AR B11AR B11AR Sample ID MW-B2-06182014 MW-B3-06182014 MW-B11AR-06182014 MW-B11AR-09242014 MW-B11AR-03252015 Sample Date 06/18/2014 06/18/2014 06/18/2014 09/24/2014 03/25/2015 Radiological (pCi/L)

Americium-241 0.00398 +/- 0.0725 0.0228 +/- 0.066 0.0837 +/- 0.107 -0.0169 +/- 0.0515 -

Niobium-94 1.77 +/- 1.62 0.665 +/- 1.87 1.53 +/- 3.08 -0.129 +/- 1.82 0.986 +/- 2.13 Plutonium-238 0.054 +/- 0.142 0.0829 +/- 0.138 0.0409 +/- 0.119 -0.0055 +/- 0.0643 -

Plutonium-239/240 0.034 +/- 0.0985 0.146 +/- 0.192 -0.0339 +/- 0.123 -0.011 +/- 0.0652 -

Plutonium-241 0 +/- 11.9 -0.739 +/- 11 0.838 +/- 12.5 -2.29 +/- 8.28 -

Strontium-90 0.652 +/- 0.691 0.612 +/- 0.672 0.611 +/- 0.634 1.32 +/- 0.736 3.52 +/- 0.925 Technetium-99 -7.41 +/- 3.45 -8.1 +/- 3.41 -8.46 +/- 3.49 -1.56 +/- 3.18 -

Tritium 160 +/- 141 194 +/- 141 161 +/- 142 34.4 +/- 140 -69.4 +/- 142 Notes:

R = Result is rejected

- = Analysis for radionuclide not performed pCi/L = picoCuries per liter U = Not detected, number is the laboratory reporting limit Reporting values exceed one or more of the regulatory criteria Duplicate analyses performed.

Attachment B to Enclosure 1 to LC-2018-0075 Page 6 of 39 Location B11AR B11AR B11AR B11AR B11AR B11AR Sample ID MW-B11AR-11122015 B11AR-120616 B11AR-052217 B11AR-D-052217 B11AR-120517 B11AR-D-120517 Sample Date 11/12/2015 12/06/2016 05/22/2017 05/22/2017 12/05/2017 12/05/2017 Radiological (pCi/L)

Americium-241 - - - - - -

Niobium-94 -1.23 +/- 3.26 - - - - -

Plutonium-238 - - - - - -

Plutonium-239/240 - - - - - -

Plutonium-241 - - - - - -

Strontium-90 1.41 +/- 0.679 0.248 U +/- 0.609 1.02 U +/- 1.01 1.44 U +/- 1.01 -0.784 UJ +/- 0.396 0.0335 U +/- 0.561 Technetium-99 - - - - - -

Tritium -86.4 +/- 146 -367 U +/- 316 -93.5 U +/- 229 -51 U +/- 224 -243 U +/- 322 -85.9 U +/- 337 Notes:

R = Result is rejected

- = Analysis for radionuclide not performed pCi/L = picoCuries per liter U = Not detected, number is the laboratory reporting limit Reporting values exceed one or more of the regulatory criteria Duplicate analyses performed.

Attachment B to Enclosure 1 to LC-2018-0075 Page 7 of 39 Location B11AR B11AR B11AR B11AR B11AR Sample ID B11AR-060418 B11AR-071019 B11AR-081419 B11AR-091018 B11AR-100918 Sample Date 6/4/2018 7/10/2018 8/14/2018 9/10/2018 10/9/2018 Radiological (pCi/L)

Americium-241 - - - - -

Niobium-94 - - - - -

Plutonium-238 - - - - -

Plutonium-239/240 - - - - -

Plutonium-241 - - - - -

Strontium-90 - - 1.00 U + 1.14 - 0.738 U + 1.09 Technetium-99 - - - - -

Tritium 309 U +/- 261 238 + U 257 32.9 U + 391 75.1 U + 206 214 U + 271 Notes:

R = Result is rejected

- = Analysis for radionuclide not performed pCi/L = picoCuries per liter U = Not detected, number is the laboratory reporting limit Reporting values exceed one or more of the regulatory criteria Duplicate analyses performed.

Attachment B to Enclosure 1 to LC-2018-0075 Page 8 of 39 Location B11R B11R B11R B11R B11R Sample ID MW-B11R-06182014 MW-B11R-09242014 MW-B11R-03252015 MW-B11R-11122015 B11R-120616 Sample Date 06/18/2014 09/24/2014 03/25/2015 11/12/2015 12/06/2016 Radiological (pCi/L)

Americium-241 0.0122 +/- 0.0626 0.0369 +/- 0.109 - - -

Niobium-94 -0.699 +/- 1.83 -1.39 +/- 1.65 -0.556 +/- 2.32 -0.284 +/- 2.31 -

Plutonium-238 0 +/- 0.12 0.0369 +/- 0.102 - - -

Plutonium-239/240 -0.0254 +/- 0.0921 0 +/- 0.102 - - -

Plutonium-241 -5.72 +/- 9.33 -3.68 +/- 8.85 - - -

Strontium-90 0.734 +/- 0.673 1.63 +/- 0.643 0.975 +/- 0.682 2.47 +/- 0.777 -0.702 U +/- 0.482 Technetium-99 -5.52 +/- 3.49 -0.4 +/- 3.28 - - -

Tritium 245 +/- 142 0 +/- 140 -191 +/- 140 -105 +/- 148 -322 U +/- 318 Notes:

R = Result is rejected

- = Analysis for radionuclide not performed pCi/L = picoCuries per liter U = Not detected, number is the laboratory reporting limit Reporting values exceed one or more of the regulatory criteria Duplicate analyses performed.

Attachment B to Enclosure 1 to LC-2018-0075 Page 9 of 39 Location B11R B11R B11R B11R B11R B11R B11R Sample ID B11R-052217 B11R-120517 B11R-060418 B11R-071018 B11R-081418 B11R-091018 B11R-100918 Sample Date 05/22/2017 12/05/2017 6/4/2018 7/10/2018 8/14/2018 9/10/2018 10/9/2018 Radiological (pCi/L)

Americium-241 - - - - - - -

Niobium-94 - - - - - - -

Plutonium-238 - - - - - - -

Plutonium-239/240 - - - - - - -

Plutonium-241 - - - - - - -

Strontium-90 0.993 U +/- 0.918 -0.313 U +/- 0.572 - - 1.21 U + 0.903 - -0.036 U + 0.960 Technetium-99 - - - - - - -

Tritium -69.3 U +/- 229 -89.2 U +/- 331 49.4 U +/- 237 -191 U + 255 200 U + 277 -19.6 U + 192 210 U + 274 Notes:

R = Result is rejected

- = Analysis for radionuclide not performed pCi/L = picoCuries per liter U = Not detected, number is the laboratory reporting limit Reporting values exceed one or more of the regulatory criteria Duplicate analyses performed.

Attachment B to Enclosure 1 to LC-2018-0075 Page 10 of 39 Location MW-200A MW-200A MW-200A MW-200A MW-200A Sample ID MW-200A-06172014 MW-200A-09242014 MW-200A-03242015 MW-200A-11112015 MW-200A-120816 Sample Date 06/17/2014 09/24/2014 03/24/2015 11/11/2015 12/08/2016 Radiological (pCi/L)

Americium-241 0.172 +/- 0.18 0.11 +/- 0.133 - - -

Niobium-94 1.08 +/- 1.75 -1.43 +/- 2.64 1.95 +/- 3.18 0.591 +/- 4.28 -

Plutonium-238 -0.0138 +/- 0.0819 0.0265 +/- 0.0635 - - -

Plutonium-239/240 0.0268 +/- 0.082 0.0583 +/- 0.0894 - - -

Plutonium-241 0 +/- 7.97 -2.23 +/- 8.05 - - -

Strontium-90 0.986 +/- 0.723 2.18 +/- 0.748 0.522 +/- 0.644 2.41 +/- 0.919 -1.8 U +/- 0.916 Technetium-99 3.55 +/- 3.16 -1.57 +/- 3.2 - - -

Tritium 52.3 +/- 141 68.6 +/- 140 -156 +/- 140 -17.3 +/- 147 -469 U +/- 326 Notes:

R = Result is rejected

- = Analysis for radionuclide not performed pCi/L = picoCuries per liter U = Not detected, number is the laboratory reporting limit b Reporting values exceed one or more of the regulatory criteria Duplicate analyses performed.

Attachment B to Enclosure 1 to LC-2018-0075 Page 11 of 39 Location MW-200A MW-200A MW-200A MW-200A MW-200A MW-200A Sample ID MW-200A-052217 MW-200A-120617 MW-200A-060518 MW-200A-071118 MW-200A-081418 MW-200A-091018 Sample Date 05/22/2017 12/06/2017 6/5/2018 7/11/2018 8/14/2018 9/10/2018 Radiological (pCi/L)

Americium-241 - - - - - -

Niobium-94 - - - - - -

Plutonium-238 - - - - - -

Plutonium-239/240 - - - - - -

Plutonium-241 - - - - - -

Strontium-90 -0.567 U +/- 0.981 1.31 U +/- 0.935 - - 1.31 U + 1.11 -

Technetium-99 - - - - - -

Tritium -174 U +/- 221 244 U +/- 355 -21.4 U +/- 240 -226 U + 247 212 U + 274 19.1 U + 191 Notes:

R = Result is rejected

- = Analysis for radionuclide not performed pCi/L = picoCuries per liter U = Not detected, number is the laboratory reporting limit Reporting values exceed one or more of the regulatory criteria Duplicate analyses performed.

Attachment B to Enclosure 1 to LC-2018-0075 Page 12 of 39 Location MW-200A MW-200A MW-200A Sample ID MW-200A-D-091018 MW-200A-100918 MW-200A-D-100918 Sample Date 9/10/2018 10/9/2018 10/9/2018 Radiological (pCi/L)

Americium-241 - - -

Niobium-94 - - -

Plutonium-238 - - -

Plutonium-239/240 - - -

Plutonium-241 - - -

Strontium-90 - -0.394 U + 0.767 1.02 U + 0.922 Technetium-99 - - -

Tritium 73.7 U + 208 35.7 U + 255 12.3 U + 254 Notes:

R = Result is rejected

- = Analysis for radionuclide not performed pCi/L = picoCuries per liter U = Not detected, number is the laboratory reporting limit Reporting values exceed one or more of the regulatory criteria Duplicate analyses performed.

Attachment B to Enclosure 1 to LC-2018-0075 Page 13 of 39 Location MW-200B MW-200B MW-200B MW-200B MW-200B Sample ID MW-200B-06172014 MW-200B-09242014 MW-200B-03242015 MW-200B-D-03242015 MW-200B-11112015 Sample Date 06/17/2014 09/24/2014 03/24/2015 03/24/2015 11/11/2015 Radiological (pCi/L)

Americium-241 0.371 +/- 0.232 0.229 +/- 0.25 - - -

Niobium-94 0.847 +/- 2.49 -0.268 +/- 2.7 1.22 +/- 2.58 0.332 +/- 1.97 1.1 +/- 2.34 Plutonium-238 0.0151 +/- 0.0628 -0.0065 +/- 0.076 - - -

Plutonium-239/240 -0.0157 +/- 0.0628 0 +/- 0.106 - - -

Plutonium-241 4.49 +/- 6.56 8.49 +/- 10.5 - - -

Strontium-90 0.998 +/- 0.758 1.55 +/- 0.731 2.15 +/- 0.813 3.68 +/- 1.01 0.83 +/- 0.897 Technetium-99 5.08 +/- 3.19 -1.54 +/- 3.14 - - -

Tritium 124 +/- 144 51.7 +/- 140 -122 +/- 141 -105 +/- 142 -52 +/- 147 Notes:

R = Result is rejected

- = Analysis for radionuclide not performed pCi/L = picoCuries per liter U = Not detected, number is the laboratory reporting limit Reporting values exceed one or more of the regulatory criteria Duplicate analyses performed.

Attachment B to Enclosure 1 to LC-2018-0075 Page 14 of 39 Location MW-200B MW-200B MW-200B MW-200B MW-200B Sample ID MW-200B-120816 MW-200B-052217 MW-200B-120617 MW-200B-060518 MW-200B-0711818 Sample Date 12/08/2016 05/22/2017 12/06/2017 6/5/2018 7/11/2018 Radiological (pCi/L)

Americium-241 - - - - -

Niobium-94 - - - - -

Plutonium-238 - - - - -

Plutonium-239/240 - - - - -

Plutonium-241 - - - - -

Strontium-90 0.531 U +/- 0.485 1.44 U +/- 1.14 0.548 U +/- 0.849 - -

Technetium-99 - - - - -

Tritium -107 U +/- 357 38.5 U +/- 233 128 U +/- 346 -10.8 U +/- 236 -214 U + 250 Notes:

R = Result is rejected

- = Analysis for radionuclide not performed pCi/L = picoCuries per liter U = Not detected, number is the laboratory reporting limit Reporting values exceed one or more of the regulatory criteria Duplicate analyses performed.

Attachment B to Enclosure 1 to LC-2018-0075 Page 15 of 39 Location MW-200B MW-200B MW-200B Sample ID MW-200B-081418 MW-200B-091018 MW-200B-100918-1250 Sample Date 8/14/2018 9/10/2018 10/9/2018 Radiological (pCi/L)

Americium-241 - - -

Niobium-94 - - -

Plutonium-238 - - -

Plutonium-239/240 - - -

Plutonium-241 - - -

Strontium-90 0.677 U + 1.06 - -0.893 U + 0.706 Technetium-99 - - -

Tritium -77.6 U + 284 81.2 U + 197 233 U + 271 Notes:

R = Result is rejected

- = Analysis for radionuclide not performed pCi/L = picoCuries per liter U = Not detected, number is the laboratory reporting limit Reporting values exceed one or more of the regulatory criteria Duplicate analyses performed.

Attachment B to Enclosure 1 to LC-2018-0075 Page 16 of 39 Location MW-201A MW-201A MW-201A MW-201A MW-201A Sample ID - - MW-201A-06172014 MW-201A-D-06172014 MW-201A-09242014 Sample Date June 2013 November 2013 06/17/2014 06/17/2014 09/24/2014 Radiological (pCi/L)

Americium-241 - - 0.0946 +/- 0.124 0.0301 +/- 0.0792 0.14 +/- 0.14 Niobium-94 - - 0.373 +/- 2.03 0.349 +/- 2.4 0.656 +/- 1.92 Plutonium-238 - - 0.0533 +/- 0.115 -0.0739 +/- 0.0898 -0.0359 +/- 0.0888 Plutonium-239/240 - - -0.00686 +/- 0.0802 -0.00672 +/- 0.0786 0 +/- 0.117 Plutonium-241 - - -0.485 +/- 6.95 0 +/- 8.85 -0.692 +/- 10 Strontium-90 2.05 1.18 U 0.0686 +/- 0.709 1.54 +/- 0.748 0.921 +/- 0.716 Technetium-99 - - 3.92 +/- 3.15 6.96 +/- 3.31 -0.794 +/- 3.25 Tritium 572 235 70.3 +/- 142 87 +/- 141 86.7 +/- 142 Notes:

R = Result is rejected

- = Analysis for radionuclide not performed pCi/L = picoCuries per liter U = Not detected, number is the laboratory reporting limit Reporting values exceed one or more of the regulatory criteria Duplicate analyses performed.

Attachment B to Enclosure 1 to LC-2018-0075 Page 17 of 39 Location MW-201A MW-201A MW-201A MW-201A MW-201A Sample ID MW-201A-03252015 MW-201A-11112015 MW-201A-120816 MW-201A-052317 MW-201A-120617 Sample Date 03/25/2015 11/11/2015 12/08/2016 05/23/2017 12/06/2017 Radiological (pCi/L)

Americium-241 - - - - -

Niobium-94 0.0629 +/- 3.25 1.16 +/- 2.17 - - -

Plutonium-238 - - - - -

Plutonium-239/240 - - - - -

Plutonium-241 - - - - -

Strontium-90 0.866 +/- 0.663 1.25 +/- 0.705 0.301 U +/- 0.615 1.47 U +/- 1.03 0.343 U +/- 0.599 Technetium-99 - - - - -

Tritium 52.1 +/- 144 -17.3 +/- 148 -375 U +/- 331 -115 U +/- 225 -192 U +/- 322 Notes:

R = Result is rejected

- = Analysis for radionuclide not performed pCi/L = picoCuries per liter U = Not detected, number is the laboratory reporting limit Reporting values exceed one or more of the regulatory criteria Duplicate analyses performed.

Attachment B to Enclosure 1 to LC-2018-0075 Page 18 of 39 Location MW-201A MW-201A MW-201A MW-201A MW-201A MW-201A Sample ID MW-201A-020118 MW-201A-060618 MW-201A-071118 MW-201A-081518 MW-201A-091118 MW-201A-101018 Sample Date 2/1/2018 6/6/2018 7/11/2018 8//15/2018 9/11/2018 10/10/2018 Radiological (pCi/L) - - -

Americium-241 - - - - - -

Niobium-94 - - - - - -

Plutonium-238 - - - - - -

Plutonium-239/240 - - - - - -

Plutonium-241 - - - - - -

Strontium-90 - - - 1.44 U + 1.08 - 0.429 U + 0.886 Technetium-99 - - - - - -

Tritium 264 U +/- 255 245 U +/- 255 132 U + 287 24.4 U + 292 326 U + 265 587 U + 340 Notes:

R = Result is rejected

- = Analysis for radionuclide not performed pCi/L = picoCuries per liter U = Not detected, number is the laboratory reporting limit Reporting values exceed one or more of the regulatory criteria Duplicate analyses performed.

Attachment B to Enclosure 1 to LC-2018-0075 Page 19 of 39 Location MW-201B MW-201B MW-201B MW-201B MW-201B MW-201B Sample ID - - MW-201B-06172014 MW-201B-09242014 MW-201B-03252015 MW-201B-11112015 Sample Date June 2013 Novmeber 2013 06/17/2014 09/24/2014 03/25/2015 11/11/2015 Radiological (pCi/L)

Americium-241 - - 0.00399 +/- 0.0726 0.028 +/- 0.0778 - -

Niobium-94 - - 1.8 +/- 1.87 0.644 +/- 1.49 0.208 +/- 2.24 1.33 +/- 2.17 Plutonium-238 - - -0.0502 +/- 0.11 0.0855 +/- 0.128 - -

Plutonium-239/240 - - 0.0236 +/- 0.0987 0.141 +/- 0.147 - -

Plutonium-241 - - -1.42 +/- 10.1 -0.585 +/- 8.48 - -

Strontium-90 2.00 3.73 U 1.02 +/- 0.716 0.541 +/- 0.709 1.27 +/- 0.735 0.876 +/- 0.732 Technetium-99 - - 1.17 +/- 3.06 -1.95 +/- 3.17 - -

Tritium 506 150 105 +/- 143 -34.2 +/- 138 17.3 +/- 143 34.1 +/- 146 Notes:

R = Result is rejected

- = Analysis for radionuclide not performed pCi/L = picoCuries per liter U = Not detected, number is the laboratory reporting limit Reporting values exceed one or more of the regulatory criteria Duplicate analyses performed.

Attachment B to Enclosure 1 to LC-2018-0075 Page 20 of 39 Location MW-201B MW-201B MW-201B MW-201BR MW-201BR MW-201BR Sample ID MW-201B-120816 MW-201B-052317 MW-201B-060618 MW-201BR-071118 MW-201BR-081518 MW-201BR-091118 Sample Date 12/08/2016 05/23/2017 6/6/2018 7/11/2018 8/15/2018 9/11/2018 Radiological (pCi/L)

Americium-241 - - - - - -

Niobium-94 - - - - - -

Plutonium-238 - - - - - -

Plutonium-239/240 - - - - - -

Plutonium-241 - - - - - -

Strontium-90 -0.208 U +/- 0.474 1.06 U +/- 0.834 - - 0.730 U + 1.04 -

Technetium-99 - - - - - -

Tritium -123 U +/- 307 106 U +/- 235 176 U +/- 250 186 U + 261 -151 U + 271 28.4 U + 201 Notes:

R = Result is rejected

- = Analysis for radionuclide not performed pCi/L = picoCuries per liter U = Not detected, number is the laboratory reporting limit Reporting values exceed one or more of the regulatory criteria Duplicate analyses performed.

Attachment B to Enclosure 1 to LC-2018-0075 Page 21 of 39 Location MW-201BR Sample ID MW-201BR-101018 Sample Date 10/10/2018 Radiological (pCi/L)

Americium-241 -

Niobium-94 -

Plutonium-238 -

Plutonium-239/240 -

Plutonium-241 -

Strontium-90 -0.177 U + 0.771 Technetium-99 -

Tritium 113 U + 265 Notes:

R = Result is rejected

- = Analysis for radionuclide not performed pCi/L = picoCuries per liter U = Not detected, number is the laboratory reporting limit Reporting values exceed one or more of the regulatory criteria Duplicate analyses performed.

Attachment B to Enclosure 1 to LC-2018-0075 Page 22 of 39 Location MW-202A MW-202A MW-202A MW-202A MW-202A Sample ID - MW-202A-06172014 MW-202A-09232014 MW-202A-03242015 MW-202A-11112015 Sample Date November 2013 06/17/2014 09/23/2014 03/24/2015 11/11/2015 Radiological (pCi/L)

Americium-241 - 0.116 +/- 0.119 0.0662 +/- 0.126 - -

Niobium-94 - -0.355 +/- 1.64 -0.0648 +/- 1.97 -0.126 +/- 2.65 0.927 +/- 2.8 Plutonium-238 - -0.00846 +/- 0.0957 0.0113 +/- 0.0732 - -

Plutonium-239/240 - -0.0227 +/- 0.091 0.0587 +/- 0.0998 - -

Plutonium-241 - 2.2 +/- 10.6 0 +/- 9.66 - -

Strontium-90 1.18 U 1.12 +/- 0.756 1.71 +/- 0.742 0.0945 +/- 0.742 1.21 +/- 0.81 Technetium-99 - 0.388 +/- 3.03 0.797 +/- 3.29 - -

Tritium 257 336 +/- 149 -51.8 +/- 138 499 +/- 154 175 +/- 153 Notes:

R = Result is rejected

- = Analysis for radionuclide not performed pCi/L = picoCuries per liter U = Not detected, number is the laboratory reporting limit Reporting values exceed one or more of the regulatory criteria Duplicate analyses performed.

Attachment B to Enclosure 1 to LC-2018-0075 Page 23 of 39 Location MW-202A MW-202A MW-202A MW-202A MW-202A Sample ID MW-202A-120716 MW-202A-D-120716 MW-202A-052317 MW-202A-120717 MW-202A-020118 Sample Date 12/07/2016 12/07/2016 05/23/2017 12/07/2017 2/1/2018 Radiological (pCi/L)

Americium-241 - - - - -

Niobium-94 - - - - -

Plutonium-238 - - - - -

Plutonium-239/240 - - - - -

Plutonium-241 - - - - -

Strontium-90 0.236 U +/- 0.626 0.430 U +/- 0.825 0.576 U +/- 0.818 -0.359 U +/- 0.512 -

Technetium-99 - - - - -

Tritium -182 U +/- 350 -192 U +/- 317 113 U +/- 239 -11.3 U +/- 338 13200 +/- 785 Notes:

R = Result is rejected

- = Analysis for radionuclide not performed pCi/L = picoCuries per liter U = Not detected, number is the laboratory reporting limit Reporting values exceed one or more of the regulatory criteria Duplicate analyses performed.

Attachment B to Enclosure 1 to LC-2018-0075 Page 24 of 39 Location MW-202AR MW-202AR MW-202AR MW-202AR MW-202AR MW-202AR Sample ID MW-202AR-040419 MW-202A-060518 MW-202AR-071018 MW-202AR-081518 MW-202AR-091118 MW-202AR-101018 Sample Date 4/4/2018 6/6/2018 7/18/2018 8/15/2018 9/11/2018 10/10/2018 Radiological (pCi/L)

Americium-241 - - - - - -

Niobium-94 - - - - - -

Plutonium-238 - - - - - -

Plutonium-239/240 - - - - - -

Plutonium-241 - - - - - -

Strontium-90 0.304 U +/- 0.928 - - 1.49 U + 1.12 - 1.49 U + 1.02 Technetium-99 - - - - - -

Tritium 702 +/- 283 1100 +/- 305 281 U + 294 937 + 356 1040 + 374 1190 + 391 Notes:

R = Result is rejected

- = Analysis for radionuclide not performed pCi/L = picoCuries per liter U = Not detected, number is the laboratory reporting limit Reporting values exceed one or more of the regulatory criteria Duplicate analyses performed.

Attachment B to Enclosure 1 to LC-2018-0075 Page 25 of 39 Location MW-202B MW-202B MW-202B MW-202B MW-202B MW-202B Sample ID - - MW-202B-06172014 MW-202B-09232014 MW-202B-03242015 MW-202B-11112015 Sample Date June 2013 November 2013 06/17/2014 09/23/2014 03/24/2015 11/11/2015 Radiological (pCi/L)

Americium-241 - - 0.0392 +/- 0.0653 0.0948 +/- 0.121 - -

Niobium-94 - - 0.104 +/- 1.99 -1.02 +/- 2.08 -0.556 +/- 2.46 -0.254 +/- 3.96 Plutonium-238 - - 0.148 +/- 0.18 0.0363 +/- 0.0909 - -

Plutonium-239/240 - - -0.0454 +/- 0.0729 0.0525 +/- 0.0892 - -

Plutonium-241 - - 2.72 +/- 7.88 -1.76 +/- 8.49 - -

Strontium-90 1.43 1.61 U 0.605 +/- 0.701 1.58 +/- 0.748 1.05 +/- 0.733 1.54 +/- 0.793 Technetium-99 - - 2.73 +/- 2.9 -0.195 +/- 3.2 - -

Tritium 484 278 106 +/- 143 104 +/- 142 -52.1 +/- 142 0 +/- 147 Notes:

R = Result is rejected

- = Analysis for radionuclide not performed pCi/L = picoCuries per liter U = Not detected, number is the laboratory reporting limit Reporting values exceed one or more of the regulatory criteria Duplicate analyses performed.

Attachment B to Enclosure 1 to LC-2018-0075 Page 26 of 39 Location MW-202B MW-202B MW-202B MW-202B MW-202B MW-202B Sample ID MW-202B-120716 MW-202B-052317 MW-202B-120717 MW-202B-040318 MW-202B-060518 MW-202B-D-060518 Sample Date 12/07/2016 05/23/2017 12/07/2017 4/3/2018 6/5/2018 6/5/2018 Radiological (pCi/L)

Americium-241 - - - - - -

Niobium-94 - - - - - -

Plutonium-238 - - - - - -

Plutonium-239/240 - - - - - -

Plutonium-241 - - - - - -

Strontium-90 0.145 U +/- 0.687 1.30 U +/- 1.17 0.39 U +/- 0.606 -0.418 U +/- 0.541 - -

Technetium-99 - - - - - -

Tritium -197 U +/- 349 54.5 U +/- 236 -193 U +/- 320 113 U +/- 239 -11.2 U +/- 231 -220 +/- 217 Notes:

R = Result is rejected

- = Analysis for radionuclide not performed pCi/L = picoCuries per liter U = Not detected, number is the laboratory reporting limit Reporting values exceed one or more of the regulatory criteria Duplicate analyses performed.

Attachment B to Enclosure 1 to LC-2018-0075 Page 27 of 39 Location MW-202B MW-202B MW-202B MW-202B Sample ID MW-202B-071018 MW-202B-081518 MW-202B-091118 MW-202B-101018 Sample Date 7/10/2018 8/15/2018 9/11/2018 10/10/2018 Radiological (pCi/L)

Americium-241 - - - -

Niobium-94 - - - -

Plutonium-238 - - - -

Plutonium-239/240 - - - -

Plutonium-241 - - - -

Strontium-90 - 0.593 U + 0.985 - -0.202 U + 0.837 Technetium-99 - - - -

Tritium - 170 + 257 -290 U + 272 163 U + 230 208 U + 274 Notes:

R = Result is rejected

- = Analysis for radionuclide not performed pCi/L = picoCuries per liter U = Not detected, number is the laboratory reporting limit Reporting values exceed one or more of the regulatory criteria Duplicate analyses performed.

Attachment B to Enclosure 1 to LC-2018-0075 Page 28 of 39 Location MW-203A MW-203A MW-203A MW-203A MW-203A Sample ID - - MW-203A-06172014 MW-203A-09232014 MW-203A-03242015 Sample Date June 2013 November 2013 06/17/2014 09/23/2014 03/24/2015 Radiological (pCi/L)

Americium-241 - - 0.0294 +/- 0.085 0.251 +/- 0.305 -

Niobium-94 - - 1.59 +/- 1.66 0.0853 +/- 2.05 0.021 +/- 3.34 Plutonium-238 - - -0.0567 +/- 0.0748 0.0708 +/- 0.106 -

Plutonium-239/240 - - -0.0227 +/- 0.0691 0.0915 +/- 0.12 -

Plutonium-241 - - 4.07 +/- 8.44 0.504 +/- 7.34 -

Strontium-90 1/2/1900 1.87 U 1.17 +/- 0.709 1.52 +/- 0.782 0.177 +/- 0.665 Technetium-99 - - 4.36 +/- 3.2 -1.24 +/- 3.37 -

Tritium N/A 3/24/1901 279 +/- 146 -34.4 +/- 138 -34.7 +/- 142 Notes:

R = Result is rejected

- = Analysis for radionuclide not performed pCi/L = picoCuries per liter U = Not detected, number is the laboratory reporting limit Reporting values exceed one or more of the regulatory criteria Duplicate analyses performed.

Attachment B to Enclosure 1 to LC-2018-0075 Page 29 of 39 Location MW-203A MW-203A MW-203A MW-203A MW-203A MW-203A Sample ID MW-203A-11112015 MW-203A-120716 MW-203A-052317 MW-203A-120717 MW-203A-020118 MW-203A-040418 Sample Date 11/11/2015 12/07/2016 05/23/2017 12/07/2017 2/1/2018 4/4/2018 Radiological (pCi/L)

Americium-241 - - - - - -

Niobium-94 1.68 +/- 2.05 - - - - -

Plutonium-238 - - - - - -

Plutonium-239/240 - - - - - -

Plutonium-241 - - - - - -

Strontium-90 1.37 +/- 1.31 1.01 U +/- 0.834 -0.44 U +/- 1.03 -0.517 U +/- 0.526 - -0.30 U +/- 0.935 Technetium-99 - - - - - -

Tritium 104 +/- 150 -303 U +/- 340 -6.35 U +/- 227 13000 +/- 874 24200 +/- 1040 12100 +/- 722 Notes:

R = Result is rejected

- = Analysis for radionuclide not performed pCi/L = picoCuries per liter U = Not detected, number is the laboratory reporting limit Reporting values exceed one or more of the regulatory criteria Duplicate analyses performed.

Attachment B to Enclosure 1 to LC-2018-0075 Page 30 of 39 Location MW-203A MW-203A MW-203A MW-203A MW-203A Sample ID MW-203A-060718 MW-203A-071118 MW-203A-081518 MW-203A-091118 MW-203A-101018 Sample Date 6/6/2018 7/11/2018 8/15/2018 9/11/2018 10/10/2018 Radiological (pCi/L)

Americium-241 - - - - -

Niobium-94 - - - - -

Plutonium-238 - - - - -

Plutonium-239/240 - - - - -

Plutonium-241 - - - - -

Strontium-90 - - 0.277 U + 1.02 - 0.314 U + 0.817 Technetium-99 - - - - -

Tritium 11900 +/- 713 2360 + 410 315 U + 288 616 + 347 350 U + 321 Notes:

R = Result is rejected

- = Analysis for radionuclide not performed pCi/L = picoCuries per liter U = Not detected, number is the laboratory reporting limit Reporting values exceed one or more of the regulatory criteria Duplicate analyses performed.

Attachment B to Enclosure 1 to LC-2018-0075 Page 31 of 39 Location MW-203B MW-203B MW-203B MW-203B MW-203B MW-203B Sample ID - - MW-203B-06172014 MW-203B-09232014 MW-203B-D-09232014 MW-203B-03242015 Sample Date June 2013 November 2013 06/17/2014 09/23/2014 09/23/2014 03/24/2015 Radiological (pCi/L)

Americium-241 - - 0.0764 +/- 0.098 0.103 +/- 0.124 -0.00499 +/- 0.0564 -

Niobium-94 - - 1.5 +/- 2.34 2.16 +/- 1.92 0.566 +/- 2.32 0.807 +/- 1.57 Plutonium-238 - - -0.0587 +/- 0.129 0.0812 +/- 0.113 -0.0265 +/- 0.106 -

Plutonium-239/240 - - -0.0395 +/- 0.126 0.0597 +/- 0.0916 -0.00882 +/- 0.103 -

Plutonium-241 - - 10.3 +/- 13.6 -3.71 +/- 8.92 -6.33 +/- 13 -

Strontium-90 1/2/1900 2.40 U 0.823 +/- 0.671 1.91 +/- 0.765 1.94 +/- 0.734 1.12 +/- 0.682 Technetium-99 - - 4.17 +/- 3.2 -3.32 +/- 3.16 -1.38 +/- 3.21 -

Tritium 2/23/1901 8/22/1900 279 +/- 146 121 +/- 143 68.8 +/- 140 -139 +/- 141 Notes:

R = Result is rejected

- = Analysis for radionuclide not performed pCi/L = picoCuries per liter U = Not detected, number is the laboratory reporting limit Reporting values exceed one or more of the regulatory criteria Duplicate analyses performed.

Attachment B to Enclosure 1 to LC-2018-0075 Page 32 of 39 Location MW-203B MW-203B MW-203B MW-203B MW-203B Sample ID MW-203B-11112015 MW-203B-D-11112015 MW-203B-120716 MW-203B-052317 MW-203B-120717 Sample Date 11/11/2015 11/11/2015 12/07/2016 05/23/2017 12/07/2017 Radiological (pCi/L)

Americium-241 - - - - -

Niobium-94 1.51 +/- 2.29 -0.947 +/- 2.33 - - -

Plutonium-238 - - - - -

Plutonium-239/240 - - - - -

Plutonium-241 - - - - -

Strontium-90 0.737 +/- 0.781 1.21 +/- 0.823 0.210 U +/- 0.593 0.287 U +/- 0.796 -0.256 U +/- 0.538 Technetium-99 - - - - -

Tritium -154 +/- 143 -121 +/- 145 -297 U +/- 335 101 U +/- 241 13.1 U +/- 338 Notes:

R = Result is rejected

- = Analysis for radionuclide not performed pCi/L = picoCuries per liter U = Not detected, number is the laboratory reporting limit Reporting values exceed one or more of the regulatory criteria Duplicate analyses performed.

Attachment B to Enclosure 1 to LC-2018-0075 Page 33 of 39 Location MW-203B MW-203B MW-203B MW-203B MW-203B MW-203B Sample ID MW-203B-040418 MW-203B-060718 MW-203B-071118 MW-203B-081518 MW-203B-091118 MW-203B-101018 Sample Date 4/4/2018 6/7/2018 7/11/2018 8/5/2018 9/11/2018 10/10/2018 Radiological (pCi/L)

Americium-241 - - - - - -

Niobium-94 - - - - - -

Plutonium-238 - - - - - -

Plutonium-239/240 - - - - - -

Plutonium-241 - - - - - -

Strontium-90 -0.00534 U +/- 0.995 - - 0.777 U + 1.05 - 0.277 + 0.802 Technetium-99 - - - - - -

Tritium 226 U +/- 246 - 43.8 U +/- 231 -167 U + 260 206 U + 306 324 U + 261 457 U + 299 Notes:

R = Result is rejected

- = Analysis for radionuclide not performed pCi/L = picoCuries per liter U = Not detected, number is the laboratory reporting limit Reporting values exceed one or more of the regulatory criteria Duplicate analyses performed.

Attachment B to Enclosure 1 to LC-2018-0075 Page 34 of 39 Location MW-204A MW-204A MW-204A MW-204A MW-204A Sample ID - - MW-204A-06172014 MW-204A-09232014 MW-204A-03242015 Sample Date June 2013 November 2013 06/17/2014 09/23/2014 03/24/2015 Radiological (pCi/L)

Americium-241 - - 0.156 +/- 0.149, 0.0363 +/- 0.0956 0.106 +/- 0.115 -

Niobium-94 - - 0.226 +/- 1.01 0.118 +/- 2.46 -0.241 +/- 3.77 Plutonium-238 - - -0.0512 +/- 0.115 -0.000645 +/- 0.0685 -

Plutonium-239/240 - - -0.0249 +/- 0.0758 -0.00548 +/- 0.0641 -

Plutonium-241 - - 4.07 +/- 8.45 -3.97 +/- 8.17 -

Strontium-90 1/2/1900 1.18 U 2.01 +/- 0.676 1.94 +/- 0.735 4.52 +/- 1.08 Technetium-99 - - 6.95 +/- 3.3 -1.96 +/- 3.19 -

Tritium 397 193 106 +/- 143 68.8 +/- 140 -52 +/- 142 Notes:

R = Result is rejected

- = Analysis for radionuclide not performed pCi/L = picoCuries per liter U = Not detected, number is the laboratory reporting limit Reporting values exceed one or more of the regulatory criteria Duplicate analyses performed.

Attachment B to Enclosure 1 to LC-2018-0075 Page 35 of 39 Location MW-204A MW-204A MW-204A MW-204A MW-204A Sample ID MW-204A-11112015 MW-204A-120716 MW-204A-052217 MW-204A-120617 MW-204A-060718 Sample Date 11/11/2015 12/07/2016 05/22/2017 12/06/2017 6/7/2018 Radiological (pCi/L)

Americium-241 - - - - -

Niobium-94 1.52 +/- 2.1 - - - -

Plutonium-238 - - - - -

Plutonium-239/240 - - - - -

Plutonium-241 - - - - -

Strontium-90 0.761 +/- 0.704 0.428 U +/- 0.958 0.463 U +/- 1.18 0.38 U +/- 0.595 -

Technetium-99 - - - - -

Tritium 17.3 +/- 148 -206 U +/- 340 22.4 U +/- 236 211 U +/- 356 329 U +/- 260 Notes:

R = Result is rejected

- = Analysis for radionuclide not performed pCi/L = picoCuries per liter U = Not detected, number is the laboratory reporting limit Reporting values exceed one or more of the regulatory criteria Duplicate analyses performed.

Attachment B to Enclosure 1 to LC-2018-0075 Page 36 of 39 Location MW-204A MW-204A MW-204A MW-204A MW-204A MW-204A Sample ID MW-204A-071218 MW-204A-D-071218 MW-204A-081418 MW-204A-081418 MW-204A-091218 MW-204A-100918 Sample Date 7/12/2018 7/12/2018 8/14/2018 8/14/2018 9/12/2018 10/9/2018 Radiological (pCi/L)

Americium-241 - - - - - -

Niobium-94 - - - - - -

Plutonium-238 - - - - - -

Plutonium-239/240 - - - - - -

Plutonium-241 - - - - - -

Strontium-90 - - 0.436 U + 1.02 0.0389 U + 1.02 - 0.210 U + 0.849 Technetium-99 - - - - - -

Tritium 28.2 U + 267 227 U + 258 59.6 U + 296 248 U + 313 -45.6 U + 189 331 U + 284 Notes:

R = Result is rejected

- = Analysis for radionuclide not performed pCi/L = picoCuries per liter U = Not detected, number is the laboratory reporting limit Reporting values exceed one or more of the regulatory criteria Duplicate analyses performed.

Attachment B to Enclosure 1 to LC-2018-0075 Page 37 of 39 Location MW-204B MW-204B MW-204B MW-204B Sample ID - - MW-204B-06172014 MW-204B-09232014 Sample Date June 2013 November 2013 06/17/2014 09/23/2014 Radiological (pCi/L)

Americium-241 - - 0.0824 +/- 0.146 0.269 +/- 0.351 Niobium-94 - - 1.28 +/- 1.65, -0.512 +/- 0.625 -1.88 +/- 1.76 Plutonium-238 - - -0.00928 +/- 0.109, 0.0144 +/- 0.0929 -0.0326 +/- 0.0806 Plutonium-239/240 - - 0.0628 +/- 0.157, -0.0381 +/- 0.0943 0.0702 +/- 0.108 Plutonium-241 - - -1.89 +/- 9.02, 6.17 +/- 9.99 -6.46 +/- 10.3 Strontium-90 1/2/1900 1.51 U 0.611 +/- 0.637, 0.356 +/- 0.681 1.27 +/- 0.742 Technetium-99 - - 6.31 +/- 3.26, 4.97 +/- 3.23 0.389 +/- 3.21 Tritium 2/23/1901 6/19/1900 34.9 +/- 140, 140 +/- 143 -121 +/- 137 Notes:

R = Result is rejected

- = Analysis for radionuclide not performed pCi/L = picoCuries per liter U = Not detected, number is the laboratory reporting limit Reporting values exceed one or more of the regulatory criteria Duplicate analyses performed.

Attachment B to Enclosure 1 to LC-2018-0075 Page 38 of 39 Location MW-204B MW-204B MW-204B MW-204B MW-204B Sample ID MW-204B-03242015 MW-204B-11112015 MW-204B-120716 MW-204B-052217 MW-204B-120617 Sample Date 03/24/2015 11/11/2015 12/07/2016 05/22/2017 12/06/2017 Radiological (pCi/L)

Americium-241 - - - - -

Niobium-94 0.0186 +/- 1.67 2.3 +/- 2.04 - - -

Plutonium-238 - - - - -

Plutonium-239/240 - - - - -

Plutonium-241 - - - - -

Strontium-90 0.654 +/- 0.729 1.26 +/- 0.746 0.719 U +/- 0.652 1.00 U +/- 0.908 0.937 U +/- 0.801 Technetium-99 - - - - -

Tritium -121 +/- 140 -17.3 +/- 148 -453 U +/- 327 -124 U +/- 228 -179 U +/- 325 Notes:

R = Result is rejected

- = Analysis for radionuclide not performed pCi/L = picoCuries per liter U = Not detected, number is the laboratory reporting limit Reporting values exceed one or more of the regulatory criteria Duplicate analyses performed.

Attachment B to Enclosure 1 to LC-2018-0075 Page 39 of 39 Location MW-204B MW-204B MW-204B MW-204B MW-204B Sample ID MW-204B-060718 MW-204B-071218 MW-204B-081418 MW-204B-091218 MW-204B-100918 Sample Date 6/7/2018 7/12/2018 8/14/2018 9/12/2018 10/9/2018 Radiological (pCi/L) - - -

Americium-241 - - - - -

Niobium-94 - - - - -

Plutonium-238 - - - - -

Plutonium-239/240 - - - - -

Plutonium-241 - - - - -

Strontium-90 - - 1.16 U + 1.10 - -0.342 U + 0.737 Technetium-99 - - - - -

Tritium 83.4 U +/- 241 -238 U + 243 -76.4 U + 286 7.34 U + 180 324 U + 282 Notes:

R = Result is rejected

- = Analysis for radionuclide not performed pCi/L = picoCuries per liter U = Not detected, number is the laboratory reporting limit Reporting values exceed one or more of the regulatory criteria Duplicate analyses performed.

Attachment C to Enclosure 1 to LC-2018-0075 Page 1 of 4 Figure 1: Tritium Levels for MW-201A, -202A, and 203A 25,000 20,000 15,000 Tritium (piC/L)

MW-203A MW-202A 10,000 MW-201A 5,000 0

6/1/2013 10/14/2014 2/26/2016 7/10/2017 11/22/2018 Sampling Date

Attachment C to Enclosure 1 to LC-2018-0075 Page 2 of 4 Figure 2: Tritium Levels for MW-201A 25,000 20,000 15,000 Tritium (piC/L) 10,000 5,000 497 587 572 654 413 603 422 0 235 70.2 239 244 252 426 411 521 6/1/2013 10/14/2014 2/26/2016 7/10/2017 11/22/2018 Sampling Date

Attachment C to Enclosure 1 to LC-2018-0075 Page 3 of 4 Figure 3: Tritium Levels for MW-202A 25,000 20,000 15,000 Tirtium (piC/L) 13200 10,000 5,000 1100 1040 660 658 414 607 702 937 1190 257 335 238 242 255 0 492 6/1/2013 10/14/2014 2/26/2016 7/10/2017 11/22/2018 Sampling Date

Attachment C to Enclosure 1 to LC-2018-0075 Page 4 of 4 Figure 4: Tritium Levels for MW-203A 25,000 24200 20,000 15,000 Tirtium (piC/L) 13000 12100 11900 10,000 5,000 2360 420 449 657 404 476 616 279 237 244 253 350 0

6/1/2013 10/14/2014 2/26/2016 7/10/2017 11/22/2018 Sampling Date