ML23254A383
| ML23254A383 | |
| Person / Time | |
|---|---|
| Site: | Triso-X |
| Issue date: | 09/29/2023 |
| From: | Matt Bartlett NRC/NMSS/DFM/FFLB |
| To: | Triso-X |
| Shared Package | |
| ML23254A381 | List: |
| References | |
| Download: ML23254A383 (7) | |
Text
HArlt - Chapter 1 (Hydrology) - RAIs Hydrology Request for Additional Information for the TRISO-X License Application Review RAI-1 Karst Features:
Regulatory Basis:
The information below is necessary to demonstrate compliance with the regulations in Title 10 to the Code of Federal Regulations (10 CFR) 10 CFR 70.64(a), which states in part that for the Baseline design criteria. Each prospective applicant or licensee shall address the following baseline design criteria in the design of new facilities. These include subsection 10 CFR 70.64(a)(4) which states that for, (4) Environmental and dynamic effects. The design must provide for adequate protection from environmental conditions and dynamic effects associated with normal operations, maintenance, testing, and postulated accidents that could lead to loss of safety functions. The information below is also necessary to demonstrate compliance with the regulations in 10 CFR 70.65, Additional content of applications, subsection (b)(1), which states, that the integrated safety analysis summary must contain A general description of the site with emphasis on those factors that could affect safety (i.e., meteorology, seismology).
Guidance:
Guidance on one acceptable approach for demonstrating compliance with these regulations is provided in NUREG-1520, Revision 2, Standard Review Plan for Fuel Cycle Facilities License Applications (NUREG-1520) in subsection 1.3.4, criterion 4, The application includes a summary description of the hydrology and geology (including seismicity) for the area and cites the design-basis flood event for which the facility may be safely shut down, and in subsection 1.3.4, criterion 5, The applicants descriptions are consistent with the more detailed information presented in the integrated safety analysis (ISA) summary, the environmental report (Agencywide Documents Access and Management System (ADAMS) ML22266A272), and the emergency plan, if these are applicable, which provides one acceptable approach for demonstrating compliance with the regulations.
Describe Issue:
The term karst feature as used in the application is not capturing all features related to karst that are present at the site. The geology and hydrology sections submitted with the environmental report and the LA (e.g., section 1.1.1.3, Hydrology, and section 1.1.1.4, Geology) do not acknowledge the karst features present on the Horizon Center site (HCS).
Revision 2 to Chapter 1 of the TRIOS-X License Application (LA) (ML22308A254) (page 1-7) states that, Based on the topography of the site, several shallow draws and depressions exist which may reveal karst features beneath the surface. Karst features are caused by dissolution of carbonate rocks and deep weathering along prevailing fractures and strikeoriented bedding, creating conduits and voids (open and/or clayfilled). Voids within the dolomite and limestone bedrock were encountered on the
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site during the geotechnical drilling program to support facility design. These voids encountered on the site are karst features caused by dissolution of carbonate rock.
Section 14-505 (5)(f) of the Oak Ridge Stormwater Ordinance also acknowledges that karst features may exist in the subsurface, All exposed karst features exposed by cutting of overburden must be examined by a qualified licensed professional for appropriate mitigation procedures and the erosion and control and stormwater management plan shall be amended accordingly, and Enclosure 7, TRISO-X Fuel Fabrication Facility Integrated Safety Analysis Summary, (ML22308A251), states that Based on the topography of the site, several shallow draws and depressions exist which may reveal karst features beneath the surface.
Section 3.3.3.2, Site Geology, in the environmental report for the TRISO-X Fuel Fabrication Facility (ML22266A272) describes some of the voids penetrate by geotechnical boring B-01. It states that, The largest void, estimated at 4.1 ft. (1.2 m) thick in the vertical, was encountered in the relatively shallow limestone at 9.4 ft. (2.9 m) below ground surface (bgs) in boring B-09. This large void was found beneath a shallower void (1.5 ft. [0.5 m], vertical) encountered in the same boring at 6 ft. (1.8 m) bgs.
The response to Requests for Additional Information (RAI) in the TRISO-X, LLC, Environmental Report for the Proposed Fuel Fabrication Facility dated April 14, 2023 (ML23104A419), is an example of subsurface voids not being identified as karst features. TRISO-X Response to RAI ER-SW-1 states that, These investigations, which included deep rock coring at multiple locations, did not find large voids within the bedrock formation or in the subsurface overburden profiles. Therefore, because there is no reported incidence of sinkholes on the site and the geotechnical investigations did not find any sinkholes or karst features, the cited ordinance does not apply. However, the geotechnical soil boring investigations did find voids (i.e., karst features), and the investigations did find at least one large void.
Information Needed:
The LA section 1.1.1.3, Hydrology, and section 1.1.1.4, Geology, contain information on the hydrology and the hydrogeology of the site. The following information is needed to proceed with the formal review:
Revise the geology and hydrology sections submitted with the LA and the environmental report to acknowledge that the karst features are present at the site.
RAI-2 Lamberts Quarry:
Regulatory Basis:
This RAI has the same regulatory basis as RAI 1.
Describe Issue:
The LA section 1.1.1.3, Hydrology, and section 1.1.1.4, Geology, do not include potentially risk-significant insights obtained from a detailed description of the characteristics of the Lamberts Quarry. The nearest flowing water body is the East Fork
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Poplar Creek; however, there is a body of still or standing water relatively close to the HCS for which no information was provided. It is identified as Lamberts Quarry in Figure 3 (northeast of Development Area 7) in the Implementation of Mitigation Action Plan for Parcel ED-1 on the Oak Ridge Reservation, Oak Ridge, Tennessee, dated May 21, 2013 (DOE, 2013). Information about this body of water may provide insights on the prevalence of karst features in the Pond Springs formation, the same geological unit on which the Process Building will be constructed. Although the name of the water body indicates that it was once a quarry, it may have been a natural sinkhole before quarrying started. Information on the relationship between the water bodys water surface with that of the water table of the groundwater may provide needed additional information on the hydrogeologic regime of the area.
Information Needed:
The LA section 1.1.1.3, Hydrology, and section 1.1.1.4, Geology, contain information on the hydrology and the hydrogeology of the site. The following information is needed to proceed with the formal review:
Provide a detailed description of the hydrological and hydrogeological characteristics and origin of Lamberts Quarry located in the Pond Springs formation.
RAI-3 Volumetric Runoff Rate:
Regulatory Basis:
This RAI has the same regulatory basis as RAI 1.
Describe Issue:
Section 2.4, Stormwater Calculations, in the Stormwater Pollution Prevention Plan (SWPPP) states that, The resulting increase in overall impermeability produces an increase in runoff volume; however, it does not provide overall volumetric runoff rate values from the site after development although peak flow rates are provided in Appendix D of the SWPPP. Current plan includes stormwater runoff from parking lots and other impervious areas to flow to a detention basin in the southwest corner.
Although flow from this detention basin is to the depression labeled as a sinkhole in the adjacent area (Development Area 5 in Figure 3 in DOE (2013)) and then most likely flows to the groundwater water table, Table 2 of the SWPPP incorrectly states that receiving waterbody would be an unnamed tributary of East Fork Poplar Creek. The unnamed tributary does exist; however, it terminates at the above-mentioned sinkhole.
The LA section 1.1.1.3, Hydrology does not compare and discuss calculated post-development volumetric runoff rates with the pre-development annual discharges. Table 4.4.2-1 in the TRISO-X Environmental Report (ML22266A273) provides results for post-developed flows from runoff to the outlet area at the western edge of the HCS for surface drainage area-1, or SD#1. Estimated maximum, or peak, discharge rates and detention system storage volumes for a 1-inch storm and for the 10-, 25-, 50-, and 100-year, 24-hour duration storm events were presented in the table. However, a total discharge or volume within a given time period, e.g., an annual volumetric runoff rate, is not provided. An annual discharge could be calculated using acquired metrological data from the surrounding area and would include historical storm events greater than 1-inch
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storms as discussed in sections 3.6.1.4.5 and 3.6.1.4.6 in the TRISO-X Environmental Report.
The difference between the runoff volume and peak flow rate is not clearly described and runoff volume and peak flow rates are inconsistently applied in the response to RAIs in the TRISO-X, LLC, Environmental Report for the Proposed Fuel Fabrication Facility dated April 14, 2023 (ML23104A419). For example, TRISO-X Response to RAI ER-SW-4 states that, In Tennessee, this definition would also include directing increased stormwater runoff volumes into an existing sinkhole from new upland development. As stated above, the stormwater runoff volume will not increase in the post-development condition; therefore, a Class V UIC permit is not required. However, both the SWPPP and TRISO-X Response to RAI ER-GW-2 state that the resulting increase in overall impermeability produces an increase in runoff volume. The response to RAI ER-GW-2 also contains another example of a misinterpretation between runoff volume and runoff flow rate. The response states that, The referenced manual states that, as part of a detailed site investigation, if karst features are expected to receive additional runoff after land development, it is advisable to conduct dye tracing to determine the flow direction of water entering the subsurface. The responses rational for not performing a dye test is that the rate of discharge at the outfall locations are below the pre-developed site condition. However, the adjacent depression or sinkhole will receive more runoff on average per year due to the increase in overall impermeability of the site even if peak discharge rates will be reduced for precipitation events of one inch or less.
Information Needed:
Section 1.1.1.3, Hydrology, of the TRISO-X LA contains information on the hydrology, but very little information on overall volumetric runoff, of the site. The following information is needed to proceed with the formal review:
Revise the SWPPPs Table 2, Outfall Details, for the West Outlet (SD#1, SD#2,
& SD#7) and state that the unnamed tributary flows to the depression, or sinkhole, in the adjacent area and not to the East Fork Poplar Creek.
Revise the LA section 1.1.1.3, Hydrology, to include a subsection comparing and discussing calculated pre-development and post-development volumetric runoff, e.g., an annual volumetric rate.
RAI-4 Hydrology - Runoff Water Quality:
Regulatory Basis:
This RAI has the same regulatory basis as RAI 1.
Describe Issue:
The LA provides no information of the potential changes to groundwater quality after development. The application describes stormwater runoff from parking lots and other impervious areas will flow to a detention basin in the southwest corner. Flow from this detention basin is to the depression labeled as a sinkhole in the adjacent area (Development Area 5 in Figure 3 in DOE (2013)) which then likely quickly flows to the water table. Changes to the groundwater quality may affect future users of this groundwater. Section 4.4.2.2.3.2 from the environmental report document
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ML22266A273 states that, Therefore, no degradation of water quality is expected in the downstream receiving waters or surface-oriented water users. The same section also states that, Small amounts of oil and grease, metals, and other constituents associated with vehicular activity are expected to be carried in runoff from the roads and parking areas within the site. All constituents within stormwater runoff are expected to be at or below the allowable limits set by TDEC. The LA section 1.1.1.3, Hydrology does not describe water quality or provide a technical basis as to why all constituents within stormwater runoff are expected to be at or below the allowable limits.
Information Needed:
Section 1.1.1.3, Hydrology, of the TRISO-X LA contains information on the hydrology, but very little information on water quality, of the site. The following information is needed to proceed with the formal review:
Revise LA section 1.1.1.3, Hydrology, to include a subsection on water quality in addition to providing a technical basis as to why all constituents within stormwater runoff are expected to be at or below the allowable limits.
RAI-5 Contaminated Water Resulting from Fire Suppression:
Regulatory Basis:
This RAI has the same regulatory basis as RAI 1.
Describe Issue:
It is not clear as to where liquids and foams used to suppress potential fires will flow to during and after a fire event, and what safeguards will exist to prevent contaminants originating during a fire event (i.e., contaminates emanating from a severely fire-damaged building or potential chemical contaminants used to suppress fires) from flowing outside the site boundaries in an uncontrolled manner. Section 2.6.6 in the ISA Summary discusses liquids flowing to equipment drains and floor drains and subsequently routed to a common sump for collection, and section 5.10.1 in the NFPA 801 describes how drainage or containment shall be provided and accomplished by the use of floor drains and trenches, open doorways or other wall openings, curbs for containing or directing drainage, equipment pedestals, and pits, sumps, and sump pumps. However, in case of a serious fire, considerable water may be used during efforts to douse fires, that water may likely end up around the impacted building and on the surrounding impervious parking lots. Current plans include water runoff from parking lots and other impervious areas to flow to a detention basin in the southwest corner.
Flow from this detention basin is to the depression labeled as a sinkhole in the adjacent area (Development Area 5 in Figure 3 in DOE (2013)), which then likely quickly flows to the groundwater. Changes to the groundwater quality may affect future users of this groundwater. It is not clear if the water used to suppress the fire is not expected to flow from the impacted area, and if so, what design features limit the flow of water.
Information Needed:
It is not clear to the NRC staff how contaminated water that may originate during fire events will be disposed of, and information is needed on plans to manage contaminated
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water for such a fire scenario. The following information is needed to proceed with the formal review:
Provide information on the plans to manage contaminated water for a fire scenario as discussed in the Description of Issue above.
RAI-6 Groundwater Flow Direction:
Regulatory Basis:
This RAI has the same regulatory basis as RAI 1.
Describe Issue:
Section 1.1.1.3, Hydrology, in Revision 2 to Chapter 1 of the TRIOS-X LA states that, Groundwater elevation measurements and modeling indicate that groundwater generally flows in a southwest direction toward East Fork Poplar Creek. There are no known household, public, or industrial users of groundwater downgradient of the site.
However, both statements on flow direction and users of groundwater lack supporting evidence. While Figures 3.4.1-5 and 3.4.1-6 in the same LA document show a general flow direction towards the southeast, not the southwest, it is not clear where the terminus for the groundwater movement is. It is uncertain if the groundwater from HCS discharges to East Fork Poplar Creek or flows underneath since there are no groundwater monitoring wells on the other side of the creek. Therefore, it is unknow if there are household, public, or industrial users of groundwater downgradient of the site. This is especially true if the contour lines drawn in Figure 3.4.1-5 and 3.4.1-6 are correct. The contour lines between the groundwater monitoring wells GW-5 and GW-6 show a flow that is not discharging into the creek, but rather flowing parallel to it. However, the southwest corner of the figures, which includes the depression labeled as a sinkhole (see Development Area 5 in Figure 3 in DOE (2013)), suffers from a lack of data and any contour lines drawn in this area would be associated with a large uncertainty. For example, the flow direction from GW-5 shows a flow direction to the southwest in both figures; however, an inferred hydraulic gradient could show groundwater flowing to the northeast since the both figures show a 755-foot contour line to the northeast that is five feet below that of the measured head for GW-5 (circa 760 feet). Section 1.1.1.3 in Revision 2 to Chapter 1 of the TRIOS-X LA does not include groundwater data from the areas south of the HCS. The hydrogeology downgradient of the site is uncertain and appears to be not well understood, which makes predictions of groundwater flow and transport difficult to make with any certainty. Data from additional sources south of the site are needed, especially from areas consistent with Development Area 2 and Development Area 5 (see Figure 3 from DOE, 2013) from Parcel ED-1.
Information Needed:
Section 1.1.1.3, Hydrology, of the TRISO-X LA contains information on the hydrogeology of the site, but the hydrogeology downgradient of the site is unknown. This includes water table elevations or groundwater flow direction information from the south side of East Fork Poplar Creek in addition to groundwater flow direction information from the adjacent depression towards which the future detention basin will drain. The following information is needed to proceed with the formal review:
Revise LA section 1.1.1.3, Hydrology, to include an evaluation and a discussion pertaining to this new hydrologic data.
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Reference:
DOE, 2013. Implementation of Mitigation Action Plan for Parcel ED-1 on the Oak Ridge Reservation, Oak Ridge, Tennessee. May 21, 2013.