ML24065A313

Response to Request for Additional Information Part 2-2 for the TRISO-X Environmental Report and License Application

ML24065A313
Person / Time
Site:	Triso-X
Issue date:	03/04/2024
From:	Wheeler J Triso-X
To:	Office of Nuclear Material Safety and Safeguards, Document Control Desk
References
TX0-REG-LTR-0035
Download: ML24065A313 (1)

Text

TRISO-X, LLC 801 Thompson Avenue Rockville, MD 20852

+1 301.358.5600

TX0-REG -LTR -003 5

ELECTRONIC DELIVERY

March 4, 2024

Director, Office of Nuclear Material Safety and Safeguards U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-0001

References : 1) Docket No. 70-7027

2) TRISO-X letter from Jennifer Wheeler to Director, Office of Nuclear Material Safety and Safeguards, TRISO -X Fuel Fabrication Facility Environmental Report Submittal, dated September 23, 2022

3) NRC letter from Jill Caverly, Acting Chief, Environmental Project Management Branch 2, to Jennifer Wheeler, Director, Regulatory Affairs Request For Additional Information Part 2-2 for the Application f rom TRISO-X, LLC f or Special Nuclear Material License f or Use a t a Fuel Fabrication Facility in Oak Ridge, Tennessee (Docket Number : 70-7027),

dated December 13, 2023

4) Public Meeting Announcement for January 17, 2024, TRISO -X Fuel Fabrication Facility Environmental Review - Requests for Additional Information, dated January 4, 2024

5) Email from Jill Caverly to Jennifer Wheeler, TRISO -X Environmental RAIs Part 2-2, dated January 9, 2024

6) Memo from Jill Caverly, Project Manager, to Robert Sun, Chief, Environmental Project Management Branch 2, Summary of Meeting on January 17, 2024, With TRISO -X, LLC, to Align o n the TRISO -X Draft Environmental Impact Analysis Requests For Additional Information Part 2-2, dated January 25, 2024

7) Email from Jennifer Wheeler to Jill Caverly, TRISO -X FFF EIS ---Follow -

up to public meeting on January 17 2024, dated February 22, 2024

Subject:

Response to Request for Additional Information Part 2-2 for the TRISO-X Environmental Report and License Application

TRISO-X, LLC (TRISO-X) hereby submits responses to the subject Request for Additional Information (RAI) Part 2-2, regarding the review of the Environmental Report for the TRISO-X Fuel Fabrication Facility (Reference 2). The enclosed responses are for the RAI set transmitted by letter dated Decem ber 13, 2023 (Reference 3).

TRISO-X requested an RAI clarification meeting (Reference 4) and discussed a revised response date with NRC staff (Reference 5). Based on discussions with your staff during and after a meeting held January 17, 2024 (Reference 6), TRISO-X committed to providing a written response by March 5, 2024 (Reference 7).

TX0-REG-LTR -0035

Requests for Withholding None. The enclosed submittal contains public information.

Summary of this Submittal The following Enclosure and Attachment are included with this letter.

Enclosure - RAI Part 2-2 Responses for the TRISO-X Environmental Report and License Application

Attachment - Correspondence from TDEC for Response to RAI 2-2 ER -GW -1

If there are questions or if additional information is required, please contact me at (865) 850-0893 or jwheeler@triso-x.com.

Sincerely,

Jennifer K. Wheeler, P.E.

Vice President, Regulatory Affairs

TRISO-X, LLC 801 Thompson Avenue Rockville, MD 20852

Copy: Jill Caverly, US NRC TRISO-X Regulatory Records File

TX0-REG-LTR -0035 Enclosure - RAI Part 2-2 Responses for the TRISO-X Environmental Report and License Application Groundwater Resources

RAI2-2 ER-GW-1

Provide additional documentation and discussion regarding TRISO -Xs proposed permanent stormwater management practices for the fuel fabrication facility (FFF) regarding increased stormwater discharge and the potential need for an Underground Injection Control Permit.

The U.S. Nuclear Regulatory Commission (NRC) staffs review of the TRISO-X Stormwater Pollution Protection Plan (SWPPP) (TRISO-X, 2022b) and environmental report (ER) (TRISO-X, 2022a) documentation finds that stormwater runoff discharge volume would be permanently increased by the proposed action and may discharge to a potential sinkhole located adjacent to the facility. Increased stormwater runoff volume (not peak flow rate) discharges to a sinkhole may be subject to permitting under the Tennessee Department of Environment and Conservation (TDEC) Underground Injection Control (UIC) program. Section B.4.3 Underground Injection Control Permits of the Tennessee Permanent Stormwater Management and Design Guidance Manual (TDEC 2014) states that The act of directing increased stormwater runoff from developed land into a sinkhole or other karst feature constitutes a modification and as such, becomes a de facto improved sinkhole requiring a Class V UIC permit. This is even true if the improved sinkhole is downstream of stormwater treatment practices, either on site or o-site. Additionally, local municipal code (Oak Ridge Municipal Code14-505 (5) (e) and TDEC 2014) identify requirements for when site modifications increase stormwater runoff to sinkholes located either on or near the proposed development.

The applicant notes that the general National Pollutant Discharge Elimination System (NPDES) construction permit Notice of Intent (NOI) application and SWPPP, with no references to karst, sinkholes, karst swales, disappearing streams, or similar nomenclature, were approved by both the City of Oak Ridge and TDEC. Although not identified, in figure 1, Site Location Map from the TRISO-X SWPPP, closed-depression hatching used to denote sinkholes is visible (TRISO -X, 2022b) which may indicate that one is there. Similarly, figure 3 Surface Drainage Near the Horizon Center Site, does not identify the disappearing stream or karst swale crossing the FFF site (TRISO-X, 2022a).

Please provide all correspondence with TDEC regarding verification of the need for or lack thereof for an underground injection control permit given the presence of on and near site karst features when coupled with the increased storm water discharge from the proposed action into a karst feature. If a UIC permit is needed, provide a schedule and path forward for obtaining the UIC permit.

TRISO-X Response to RAI2-2 ER-GW-1 The attachment to this enclosure provid es correspondence from the Tennessee Department of Environment and Conservation (TDEC) which confirms the lack of a need for a Class V UIC permit.

Additional discussion of the broad swale that has characteristics similar to a karst swale is provided in the response to Hydrology RAI-1, Karst Features in Enclosure 2 to the letter dated November 8, 2023 (ADAMS Accession No. ML23312A338).

Page 1 of 3 TX0-REG-LTR -0035 Enclosure - RAI Part 2-2 Responses for the TRISO-X Environmental Report and License Application RAI2-2 ER-GW-2

Clarify the discrepancy between the ER text and the request for additional information (RAI) response regarding the volume of storm water that will be discharged into West Outlet outfall.

The previous RAI response (TRISO-X, 2023) states that the above mentioned requirements are not applicable as there are no increases in stormwater volume discharges to the sinkhole.

However, while the applicants SWPPP does demonstrate that post-construction stormwater peak flow rates would be managed by the proposed permanent stormwater management practices, the SWPPP also states that runoff volumes will be increased to the West Outlet outfall (Section 2.4, Stormwater Calculations of the SWPPP, page 3). SWPPP appendix D notes that impervious surface in the West Outlet outfall drainage area would be increased by an additional 30.4 acres (25.5 acres of Asphalt/Building and 4.9 acres of Detention Basin). Under such conditions, runoff volumes would be predicted to increase for any runoff-generating storm event. Furthermore, the SWPPP runoff volume calculations for the 100-year storm event identify an additional 697,962 cubic feet (5,221,104 gallons) of stormwater discharging through the West Outlet outfall which represents a 67 percent increase in post-construction stormwater runoff volume.

TRISO-X Response to RAI2-2 ER-GW-2 Please see the response to Hydrology RAI-3, Volumetric Runoff Rate in Enclosure 2 to the letter dated November 8, 2023 (ADAMS Accession No. ML23312A338).

RAI2-2 ER-GW-3 Please confirm that the NPDES construction permit and SWPPP that were approved by the City of Oak Ridge and TDEC did not require a discussion and evaluation of onsite and in the vicinity of the site, karst features that have the potential to be impacted by the proposed project activities.

Based on the information presented in the ER Section 4.3 and research conducted by the NRC staff, karst features are present at the FFF site; however, the general NPDES construction permit coverage NOI application and SWPPP (TRISO-X, 2022b) do not identify or discuss the presence of karst features.

TRISO-X Response to RAI2-2 ER-GW-3 The SWPPP follows the guidance of the Tennessee Erosion & Sediment Control Handbook (4th Ed., August 2012). Based on this guidance, a site description and supporting information narrative is required for the SWPPP, but a discussion of karst features on the site is not required.

Page 2 of 3 TX0-REG-LTR -0035 Enclosure - RAI Part 2-2 Responses for the TRISO-X Environmental Report and License Application RAI2-2 ER-GW-4 Provide a discussion that demonstrates how karst conditions were accounted for in the proposed large stormwater detention basin design with respect to how the facility will mitigate against both developing subsurface karst features and an actual sinkhole development, should it occur. Additionally, provide a discussion on any proposed mitigation measures that may be required by the City of Oak Ridge or TDEC as well as any that would be included as part of the proposed action.

The proposed permanent stormwater best management practices (BMP) include a large, centralized stormwater basin with forebay, as presented in TRISO-Xs Facility SWPPP. The stormwater infiltration/detention basin is proposed to manage stormwater from a 149.5-acre drainage area that will include at least 30 acres of additional impervious surface. As discussed in RAI2-2 ER -GW -1, the facility is located in karst terrain, with the proposed basin BMP being situated within the vicinity of a karst swale and disappearing stream.

Large, centralized stormwater management practices constructed in karst terrain (such as basins) are considered to represent an increased risk for future sinkhole development and collapse beneath the structure. Infiltration losses from the long-term operation of the proposed stormwater management basin could accelerate dissolution of subsurface carbonate rock, leading to potential environmental impacts. Given that the proposed activity could contribute to (or even exacerbate) future karst feature development, it is unclear whether the proposed stormwater management BMPs and structures were designed considering potential karst conditions.

TRISO-X Response to RAI2-2 ER-GW-4 The TRISO-X site development will create impervious surfaces on the site from the buildings, equipment, and parking areas. In order to accommodate a stormwater management system that meets the City of Oak Ridge and TDEC requirements for Water Quality Volume (WQV) and the design basis 24-hour, 100- year recurrence interval rainfall event, a centralized stormwater detention basin with a forebay is the most feasible solution for the site. This stormwater management system accommodates detention of stormwater up to the design basis rainfall event and allows for a controlled release of flow to maintain discharge rates at or below pre-developed site conditions. Other stormwater BMPs that are considered best practices for only karst mitigation design are not practical given the quantity of stormwater from the design basis rainfall event.

In order to mitigate the potential for sinkhole development, the stormwater detention basin has an HDPE liner with clay backfill below the liner to prevent infiltration. Based on the preliminary geotechnical investigations of the site, there is expected to be at least six feet of native soil between the bottom of the basin excavation and the top of rock. The sediment basin will also be part of a periodic maintenance program that will inspect the basin and liner, clear debris and sediment, and maintain the stormwater basin in good working condition. The periodic basin and liner inspections will also be able to identify any subsidence which could indicate potential sinkhole formation below the basin, in the unlikely event that should occur.

Page 3 of 3 Burns Cunningham

From: Joshua Frazier <Joshua.Frazier@tn.gov>

Sent: Thursday, February 15, 2024 8:32 AM To: Burns Cunningham Cc: Valerie McFall; Shari Winburn

Subject:

RE: Question Regarding TRISO-X TNR136931

Notice:Thisemailoriginatedfromoutsideoftheorganization.Donotclicklinks oropenattachments unless you recognizethesenderandknow thecontentissafe.

Burns,

Hopealliswell. Yourlogicfollowsthecriteriaoutlinedinapplicablerulesandregulaons. Ifclear separaon and protecon oftheonsite featureisachieved,there isnoneed for aUICpermit.

Respectfully,

JoshFrazier lEnvironmentalConsultant DivisionofWaterResources-NaturalResources KnoxvilleEnvironmentalFieldOffice 3711MiddlebrookPike,Knoxville,TN 37921

p. 8653649500 tn.gov/environment

Tellushow weredoing!Pleasetake510 minutestocompleteTDECs CustomerServiceSurvey

From:BurnsCunningham<rcunningham@trisox.com>

Sent:Wednesday,February 14, 20243:31PM To:JoshuaFrazier<Joshua.Frazier@tn.gov>

Subject:

[EXTERNAL]RE:QuestionRegarding TRISOX TNR136931

• • • This is an EXTERNAL email. Please exercise caution. DO NOT open attachments or click links from unknown senders or unexpected email - STS-Security. ***

ThisistheemailIwas referringto.

Burns

From:BurnsCunningham Sent:Monday,January29,20241:45PM To:joshua.frazier@TN.GOV

Subject:

QuestionRegarding TRISOX TNR136931

1

Josh,

OurenvironmentalreviewersattheNRCaresll asking quesons abouttheneedfor aClassVUICpermit. TheNRChas requestedthatweprovidecorrespondencewithTDECregardingthelackofaneedfor aUICClassVpermitgiventhe presenceofonsite andnearsite karstfeatures.Thisisreferringtoakarstswale(locatedonsite) andasinkhole(located approximately400 ositefromthewestouall). AswediscussedbyphoneinNovember,aUICpermitisnotrequired becausewearenotdischargingdirectlyintotheosite sinkhole.Thewestdetenon basindischargestothesamepoint as theexisng natural drainagecourse(itisnot releasedtothesubsurface).ThislogicfollowstheTDECscreening guidanceinGDWR UIC 01 120817.

Regardingthekarstswaleonsite, thisfeatureisnotbeingusedas adischargepointandisnotbeingusedtodischarge tothesubsurface. Theexisng swaleisbeingreplacedwithtwo perimeterdrainageditchesthatcollectrunoand conveyittothedetenon system.Inanyevent,thiskarstswaleisnotpartofthescreeningprocessfor aclassVUIC permitpresentedinGDWRUIC01120817.

TheNRChasagreedthatemailcorrespondence willbeappropriatetorespondtotheirques on.So,ifyouagreewith theaboveconclusions,pleaseletme know andIcansend amoreformalemail todocumentaresponse.Feel freetogive meacallatthenumberbelow ifyouhaveany quesons.

Thanks,

Burns Cunningham Licensing Engineer

Mobile: 865.803.1352 rcunningham@triso-x.com

This message (including any attachments) is intended only for the use of the individual or entity to which it is addressed and may contain information that is non-public, proprietary, privileged, confidential, and exempt from disclosure under applicable law or may constitute attorney work product. If you are not the intended recipient, you are hereby notified that any use, dissemination, d istribution, or copying of this communication is strictly prohibited. If you have received this communication in error, notify us immediately and delete this message immediately. Thank you. TRISO-X, LLC.

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