ML23034A214

Kairos Power LLC, Changes to Preliminary Safety Analysis Report (Psar), Revision 1, Chapter 2

ML23034A214
Person / Time
Site:	Hermes
Issue date:	02/03/2023
From:	Kairos Power
To:	Office of Nuclear Reactor Regulation
Shared Package
ML23034A212	List: ML23034A213 ML23034A214
References
KP-NRC-2302-001
Download: ML23034A214 (1)

Text

KP-NRC-2302-001 Enclosure 1 Changes to PSAR, Revision 1, Chapter 2 (Non-Proprietary)

Preliminary Safety Analysis Report Site Characteristics pipelines located within 5 miles (8 km) of the site. These pipelines are evaluated further as hazards in Section 2.2.3 (Reference 2, Reference 3).

2.2.1.2 Description of Waterways The Clinch River flows southwest from Tazewell, Virginia, through the Great Appalachian Valley to Kingston, Tennessee just west of Knoxville, where it joins the Tennessee River/Watts Bar Reservoir.

Significant waterborne transport in the site vicinity is only possible on the Clinch River arm of the Watts Bar Reservoir. Annual waterborne commerce data compiled by the U.S. Army Corps of Engineers (USACE) Waterborne Commerce Statistics Center, for the period of 2001 to 2015, indicates that there were very few shipping cargos on the Clinch River, with no transport of hazardous materials (e.g.,

chemicals and related products, petroleum, ordnance) that could pose a threat to operations at the site (Reference 4, Reference 5). These shipment cargos were classified as machinery (not electric), fabricated metal products, limestone, and wood in the rough. Therefore, waterborne shipping is not evaluated further with respect to accidents and impacts on waterways, and does not warrant further consideration in determining bounding accident scenarios involving transport of hazardous materials near the site.

White Oak Dam is located approximately 5 miles north at the terminus of White Oak Creek into the Clinch River. There are no materials stored at the facility, and therefore the dam has been removed from further evaluation.

2.2.1.3 Description of Highways The most significant highway near the site is I-40, which runs roughly east-west on the opposite side of the Clinch River arm of the Watts Bar Reservoir. At its closest point, I-40 is approximately 4.9 miles (7.9 km) from the site. According to the Tennessee Department of Transportation, the annual average daily vehicle count just east of the I-40 and TN 58 interchange (approximately 4.5 miles south of the site) was 44,470 vehicles in 2018 (Reference 6).

Other larger roads near the site include TN 58, TN 61, TN 95, and TN 327, the closest of which is TN 327, located approximately 0.61 mile (0.61 km) east of the site. The intersection of TN 327 and TN 58 lies approximately 21.3 miles (1.2.1 km) east of the site. According to the Tennessee Department of Transportation, the annual average daily vehicle count at TN 327 west of the intersection with TN 58 was 2,485 in 2018 (Reference 7), and the annual average daily vehicle count at TN 58 north of the intersection with TN 237 was 12,641 in 2018 (Reference 8).

I-40 and TN 58 were identified as those roads within 5 miles (8 km) of the site on which chemicals may be transported. These are considered further in Section 2.2.3.

2.2.1.4 Description of Railroads The nearest major rail line to the site is operated by Norfolk Southern and runs roughly northeast from Harriman, Tennessee, parallel to TN 61 toward Clinton, Tennessee. At closest approach, this line is approximately 3.3 miles (5.3 km) north-northwest of the site (Figure 2.1-2). A second major rail line operated by Norfolk Southern lies south of the site and runs roughly northeast through Loudon, Tennessee, to Knoxville. At closest approach, this line is approximately 12 miles (19.3 km) from the site.

Due to the large distances from these lines to the site and the complex intervening terrain (wooded ridges and valley), accident scenarios on these lines are not evaluated further (Reference 9).

The nearest minor rail line is owned and operated by the EnergySolutions, LLC, doing business as Heritage Railroad Corporation for industrial uses. The railroad runs from the Heritage Center Industrial Park to the Blair Interchange on the Norfolk Southern main line north of the site, a distance of approximately 11.5 miles (18.5 km). Within the ETTP, the main line serves the intermodal transfer area operated by EnergySolutions and a rail car repair area operated by East Tennessee Rail Car Company.

Kairos Power Hermes Reactor 2-16 Revision 1

Preliminary Safety Analysis Report Site Characteristics for Clinch River Nuclear Site reactor(s), the Hermes site would be outside the Clinch River Nuclear Site Emergency Planning Zone (EPZ) (Reference 9).

The Coqui Pharmaceutical site is excluded from the discussion in the following sections as there is currently not enough information available for an analysis. However, the radiological effects from the radiopharmaceutical production facility at the Coqui Pharmaceutical site would be within regulatory offsite dose limits for routine operations and accidents. Additionally, the operations are expected to be similar to the SHINE Medical Technologies which received a construction permit from the NRC in 2016 for a radioisotope production facility located in Janesville, Wisconsin. SHINE Medical Technologies demonstrated in its PSAR that releases of onsite chemicals were not a hazard to personnel in the facility control room (Reference 18). As such, chemicals stored onsite at the Coqui Pharmaceutical site would similarly not be expected to have an impact on nearby facilities, including the Hermes facility.

The general aviation airport is discussed in Section 2.2.2.3 and is also evaluated on the basis of estimated information below.

The remaining facilities with potential to affect the reactor facility are evaluated below. The potential effects of those facilities in terms of design parameters or physical phenomena were identified considering guidance in Regulatory Guide 1.78, Revision 1, Evaluating the Habitability of a Nuclear Power Plant Control Room During a Postulated Hazardous Chemical Release, Regulatory Guide 1.91, Revision 2, Evaluations of Explosions Postulated to Occur at Nearby Facilities and on Transportation Routes Near Nuclear Power Plants, Regulatory Guide 4.7, Revision 3, General Site Suitability Criteria for Nuclear Power Stations, and NUREG-1537. Although the Regulatory Guides listed do not apply to the Hermes reactor, they were consulted for applicable guidance in the absence of specific guidance in NUREG-1537.

The following event categories are considered: explosions, flammable vapor clouds (delayed ignition),

toxic chemicals, and fires. The postulated events with the potential to result in a chemical release are analyzed at the following locations:

x Nearby transportation routes and nearby natural gas pipelines x Nearby chemical and fuel storage facilities x Chemicals stored or used on site 2.2.3.1 Explosions Accidents involving detonations of high explosives, munitions, chemicals, or liquid and gaseous fuels are considered for facilities and activities in the vicinity of the site or onsite where such materials are processed, stored, used, or transported in quantity. The effects of explosions are considered based on structural response to blast pressures. The effects of blast pressure from explosions from nearby railways, highways, or facilities to critical plant structures are evaluated to determine if the explosion could have an adverse effect on plant operation or could prevent a safe shutdown.

NUREG-1537 does not provide specific guidance, therefore, the guidance in Regulatory Guide 1.91, Revision 12, Evaluations of Explosions Postulated to Occur at Nearby Facilities and on Transportation Routes Near Nuclear Power Plants, was considered in determining allowable (i.e., standoff) and actual distances of hazardous chemicals transported or stored.

Regulatory Guide 1.91 cites 1 pound per square inch (psi) (6.9 kilopascal [kPa]) as a conservative value of peak positive incident overpressure, below which no significant damage would be expected. Regulatory Guide 1.91 defines this standoff distance by the relationship:

R kW1/3 (Equation 2.2-6)

Kairos Power Hermes Reactor 2-21 Revision 1

Preliminary Safety Analysis Report Site Characteristics the bounding hazard from natural gas is a potential explosion or fire, which was addressed in Section 2.2.3.2 and determined to not be a threat to Hermes.

Waterway Traffic As discussed in Section 2.2.3.2, there is an inconsequential amount of shipping on the Clinch River, and no transportation of hazardous materials. Additionally, there is no shipping on Poplar Creek. Therefore, chemicals transported by boat are not evaluated.

Highways and Railways The Hermes site safety-related area is located approximately 4.8 miles (7.7 km) from I-40 and approximately 1.2 miles from TN-58. For this analysis, these distances were also used as the distance from I-40 and TN-58, respectively, to the Hermes Main Control Room.

The hazardous chemicals evaluated are primarily based on those chemicals identified in Clinch River Nuclear Site ESPA, Part 2, SSAR (Reference 9). The selection of mobile sources for an analysis of potential impact to the Hermes Main Control Room is based on:

x Mobile sources of hazardous chemicals described in Table 2.2-4 x Stationary sources within 5 miles where deliveries or shipments could be transported on local roads x Large quantities of stationary sources elsewhere in the county where deliveries or shipments could be transported on major roads or rail lines x Direct communication with facilities regarding their types, quantities, and frequencies of shipments An evaluation of hazardous materials potentially transported on I-40 was performed using the ALOHA dispersion model for the Clinch River Nuclear Site ESPA, Part 2, SSAR (Reference 9). The results indicated that, except for anhydrous ammonia and chlorine, the distances to the identified toxicity limit for any plausible toxic vapor cloud that could form following an accidental release at the closest approach from the transportation route (I-40) are less than the minimum separation distances from the Clinch River Nuclear Site power block area to I-40 (approximately 1.1 miles). A release of anhydrous ammonia would result in a distance of 2.6 miles to the toxicity endpoint, and a release of chlorine results in a distance of 4.5 miles to the toxicity endpoint, which are both less than the 4.8 mile distance separating the site and I-40. The exceptions are the potential impacts from transportation of chemicals on TN-58. The shortest distance from the site to TN-58 is approximately 1.2 miles (6,336 feet), less than the minimum safe distance for a toxic vapor cloud of chlorine (23,760 feet) or anhydrous ammonia (13,728 feet).

Therefore, an incident involving chlorine or anhydrous ammonia on TN 58 could have an adverse impact on the Hermes Main Control Room. Therefore, the Main Control Room is designed with chlorine and ammonia detectors in the ventilation system as discussed in Section 7.4.

Onsite Chemicals The location and quantities of chemicals that would be stored at the site have not yet been determined.

The effects of toxic chemicals or fires resulting from onsite chemical storage will be evaluated in the application for an Operating License.

Nearby Facilities Four Five facilities were evaluated in the Clinch River Nuclear Site ESPA, Part 2, SSAR (Reference 9) as facilities of concern with regard to storage of chemicals with the potential for formation of toxic vapor clouds within the vicinity of the site. They were ORNL (including ORNL-URS and ORNL-Battelle), located approximately 5 miles (8 km) east of the site; TVA Kingston Fossil Plant, located approximately 7 miles (11.2 km) southwest of the site; the TVA Bull Run Fossil Plant, located approximately 15 miles (24.1 km) east of the site; the Oak Ridge Water Treatment Plant (WTP) located approximately 9.5 miles (15 km)

Kairos Power Hermes Reactor 2-29 Revision 1

Preliminary Safety Analysis Report Site Characteristics northeast of the site; and Hallsdale Powell Utility District Melton Hill Water Treatment Plant (WTP) located approximately 18 miles (29 km) east of the site. Each material was then dispositioned based on the identified physical properties of the material and whether a bounding analysis existed. The material stored at ORNL-URS identified for further analysis was nitric acid. The materials stored at ORNL-Battelle identified for further analysis with regard to toxicity potential are: anhydrous ammonia, argon, carbon dioxide, chloroform, chromic chloride, ethanol, gasoline (gasoline blend A and gasoline B), hydrogen fluoride, nitrogen, and sulfur hexafluoride. The material stored at TVA Kingston Fossil Plant and TVA Bull Run Fossil Plant identified for further analysis was anhydrous ammonia. The material stored at the Oak Ridge WTP and the Hallsdale Powell Utility District Melton Hill WTP identified for further analysis was chlorine.

In the Clinch River Nuclear Site ESPA, Part 2, SSAR, the above-identified chemicals were analyzed using the ALOHA dispersion model to determine whether the formed vapor cloud would reach the Clinch River Nuclear Site power block area with concentrations greater than the determined toxicity limit (Reference 9). In the case of each of the atmospheric gases analyzed, the distances to the IDLH/asphyxiating or other determined toxicity limit was calculated. The results indicated that any plausible toxic vapor cloud that could form would be below the IDLH or other identified toxicity limit before reaching the Clinch River Nuclear Site power block area. This conclusion would be the same for the Hermes site.

The modeling of the aforementioned facilities indicated the accidental release of the analyzed hazardous materials stored on site would not adversely affect the safe operation or shutdown of units within the Clinch River Nuclear Site power block area as indicated in the Clinch River Nuclear Site ESPA, Part 2, SSAR (Reference 9). Of the chemicals identified for analysis at ORNL-Battelle, a release of sulfur hexafluoride from ORNL-Battelle resulted in the longest distance to the toxicity endpoint, 2 miles, which is less than both the distance to the Clinch River Nuclear Site power block area and the Hermes site (located approximately 5 miles away). Therefore, the formation of a toxic vapor cloud following an accidental release of the analyzed hazardous materials stored at ORNL-Battelle would not adversely affect the safe operation or shutdown of the Hermes reactor.

The locations and quantities of chemical that would be stored onsite at the Clinch River Nuclear Site were not evaluated in the ESPA, Part 2, SSAR (Reference 9). The ESPA, Part 2, SSAR noted that the effects of toxic chemical releases from onsite chemical storage would be evaluated in the combined license application for a future reactor project (Reference 9). Chemicals stored at the future reactor site would be maintained and stored in a manner that would be protective of on-site personnel and the on-site reactor(s). Furthermore, due to the distance from the Clinch River Nuclear Site to the Hermes site, a toxic vapor cloud from the Clinch River Nuclear Site would not adversely affect the safe operation of Hermes.

2.2.3.4 Fires As demonstrated in the previous sections, analysis conducted in the Clinch River Nuclear Site ESPA, Part 2, SSAR considered potential external accidents that could lead to high heat fluxes. The analyses showed that chemicals stored at nearby facilities and transported on I-40 and TN-58 would not result in a vapor cloud with a potential to affect the Clinch River Nuclear Site. The previous sections also demonstrate that the explosive and flammable vapor cloud analyses provided in the Clinch River Nuclear Site ESPA, Part 2, SSAR are acceptable for application to the Hermes site.

The effects of fires from brush or forest fires will be evaluated in the application for an Operating License.

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Preliminary Safety Analysis Report Site Characteristics

15. Fire dynamics Tools (FDT): Quantitative Fire Hazard Analysis Methods for the U.S. Nuclear Regulatory Commission Fire Protection Inspection Program, Final Report. December 2004.

16. Federal Emergency Management Agency. Handbook of Chemical Hazard Analysis Procedures.

OSWERHCHAP. 1989. Accessed 7/18/2021. Located at:

https://www.ci.benicia.ca.us/vertical/sites/%7BF991A639-AAED-4E1A-9735-86EA195E2C8D%7D/uploads/FEMA_1989.pdf.

17. U.S. Nuclear Regulatory Commission, Fire Risk Analysis For Nuclear Power Plants. Draft Chapter 14.

2016. Accessed 7/18/2021. Located at: https://www.nrc.gov/docs/ML1408/ML14084A314.pdf.

18. SHINE Medical Technologies, LLC, SHINE Medical Isotope Production Facility Preliminary Safety Analysis Report. June August 20159.

19. EnergySolutions, Bear Creek Processing Facility. 2016. Retrieved from https://www.energysolutions.com/waste-processing/bear-creek-processing-facility/.

20. Oak Ridge National Laboratory, User Facilities, Website: https://www.ornl.gov/content/user-facilities. Accessed June 27, 2021.

21. Munger, F., What to do With White Oak Lake, Cleanup, EPA, Oak Ridge EM, ORNL, TDEC. July 09, 2015. Retrieved from http://knoxblogs.com/atomiccity/2015/07/09/what-to-do-with-white-oak-lake/.

22. Van Winkle, J.E., Baseline Environmental Analysis Report for the K-1251 Barge Facility at the East Tennessee Technology Park, Oak Ridge, Tennessee. 2007. Retrieved from https://www.osti.gov/biblio/964674-EpJWXe/.

23. Krause, C., Medical Isotope Firm CEO tells of plans for OR facility, The Oak Ridger. March 19, 2020.

Retrieved from https://www.oakridger.com/story/news/technology/2020/03/19/medical-isotope-firm-ceo--tells-of-plans-for-or-facility/112376002/.

24. Roane Regional Business & Technology Park, Roane ECD, Website: https://www.roaneecd.com/sites/roane-regional-business-tech-park/. Accessed June 27, 2021.

25. City of Oak Ridge, Tennessee, Horizon Center Industrial Park, Website: http://oridb.net/horizon-center-park/. Accessed 06/27/2021.

26. Not Used.

27. Pounds, B., UT-Battelle Gives City $500K for Airport, Oak Ridger, Aviation Pros. March 24, 2021.

Retrieved from https://www.aviationpros.com/airports/news/21215666/utbattelle-gives-city-500k-for-airport.

28. Oak Ridge Municipal Planning Commission, Virtual Regular Business Meeting. March 18, 2021.

Retrieved from http://oakridgetn.gov/images/uploads/Documents/Boards&Commissions/Planning%20Commission/

Agenda/PC_Packet_03_18_2021.pdf.

29. National Institute for Occupational Safety and Health (NIOSH), NIOSH Pocket Guide to Chemical Hazards. September 2007.

30. U.S. Environmental Protection Agency and National Oceanic and Atmospheric Administrations Office of Response and Restoration, Computer-Aided Management of Emergency Operations (CAMEO), Website: https://www.epa.gov/cameo.

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Preliminary Safety Analysis Report Site Characteristics Table 2.2-1: Nearby Facilities (Page 2 of 2)

Location Project Name Summary of Project (from Reactor building) Status Notes Industrial Facilities Continued Hallsdale Water Treatment Plant Municipal waste water treatment facility Approximately 18 mi east Operational Due to its distance to the site, accidents due to the current materials and operations at this facility is not expected to affect the site.

City of Oak Ridge Water Treatment Municipal waste water treatment facility Approximately 9.510 mi Operational Due to its distance to the site, Plant northeast accidents due to the current materials and operations at this facility is not expected to affect the site.

Transportation Proposed General Aviation Airport at Development of a general aviation airport Approximately 1.1 miles Proposed Close proximity and potential for the East Tennessee Technology Park east overlapping construction timeline Heritage Center (Reference 10, Reference 27)

Residential Facilities The Preserve at Clinch River water Residential water and wastewater treatment Approximately 2 Operational since treatment facility facility miles south 2002 (Reference 28)

Kairos Power Hermes Reactor 2-35 Revision 1

Preliminary Safety Analysis Report Site Characteristics measurements at 20 meters. Tower L is approximately 1.6 km southeast of the site and has multiple measurement levels at 15 and 30 meters.

Hourly average (scalar) wind speeds at the 20-m level are available for this climate review from Tower J during 2018-2020, from the 10-meter or 15-meter level plus the 30-meter level during 2016-2020 from the Tower L, from the 10-meter level at the Oak Ridge airport station during 1999-2020, and from the 10-m level at the Knoxville Airport during 1981-2020. The anemometer on Tower L was located at the 10-m level from January 2016-October 2017 and was moved in November 2017 to the 15-meter level where it remained through May 2021. The wind data from all 5 years were analyzed together.

The maximum hourly average wind speed for the three years of data analyzed (2018-2020) at Tower J is 24.8 mph. The maximum hourly average wind speed for the five years of data analyzed (2016-2020) at Tower L is 21.4 mph at the 10-m or 15-meter level and 24.4 mph at the 30-meter level. In comparison, Oak Ridge has a maximum hourly average wind speed of 29.0 mph, and Knoxville has a maximum hourly average wind speed of 60 mph. Tower L recorded a peak wind speed of 78.3 mph at the 15-meter level and 84.5 mph at the 30-meter level. Oak Ridge recorded a peak wind speed of 53 mph, and Knoxville recorded a peak wind speed of 68 mph.

For a 100-year return period, the fastest mile of wind in the site area is approximately 90 mph (Reference 11).

2.3.1.6 Precipitation Extremes Historical precipitation data for the site were obtained from several surrounding National Weather Service (NWS) and Tennessee Valley Authority (TVA) sites (Reference 5, Reference 12, Reference 13, Reference 14, Reference 15), and are summarized in Table 2.3-1. Based on the similarity of the maximum recorded 24-hour and monthly totals among these stations and the areal distribution of these stations around the site, the data suggest that these statistics are reasonably representative of precipitation extremes that might be expected at the site. Droughts are uncommon in the vicinity of the site. Records indicate that 16 episodes of severe drought have occurred in the past 200 years. The worst was the decade of the 1980s, the driest overall period in the states history. Several severe heat waves hit the continental United States throughout the 1980s, including Tennessee, causing severe to extreme drought conditions in eastern Tennessee as classified by the Palmer z-Index (Reference 16, Reference 17, Reference 18, Reference 19).

The maximum estimated annual precipitation is in the range of 47-53 inches. The maximum 24-hour rainfall is less than 10 inches, and the maximum monthly rainfall is less than 20 inches (see Table 2.3-1 for details). The probable maximum precipitation (PMP) is discussed in Section 2.3.2.6.

The average annual snowfall in the vicinity of the site is less than 12 inches. Normal and extreme snowfall events are discussed in Subsection 2.3.1.11.

2.3.1.7 Tornadoes The probability of a tornado occurring at the site is low based on records from the NWS Morristown Tornado Database (Reference 20) and the NCDC Storm Events Database (Reference 7). During the 71-year period of 1950-2020, five tornadoes were reported within 10 miles of the site (Table 2.3-2). The intensities ranged from F0/EF0 to F3/EF3.

Based on the tornado strike probability presented in NUREG/CR-4461 (Reference 22), the number of tornado events from 1950 through August 2003 within a 2-degree box surrounding the site is 226. This gives an annual average of four tornado events striking somewhere within the 2-degree box.

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Preliminary Safety Analysis Report Site Characteristics 2.3.1.8 Hurricanes Hurricane winds are mainly a concern for coastal locations as shown by the wind speed contours presented in Regulatory Guide 1.221, Design-Basis Hurricane and Hurricane Missiles for Nuclear Power Plants (Reference 21), and NUREG/CR-7005, Technical Basis for Regulatory Guidance on Design-Basis Hurricane Wind Speeds for Nuclear Power Plants (Reference 23). Regulatory Guide 1.221 is for power reactors and not applicable for the Hermes reactor, but is used as guidance specifically on hurricane wind speed. Due to the rapid dissipation of hurricane winds as they move inland away from their oceanic energy source, hurricane winds should not be a concern for the site. The wind speed contours in Regulatory Guide 1.221 and NUREG/CR-7005 stop well short of the site location with a wind speed contour of 130 mph.

Due to the significant inland distance from both the Atlantic Ocean and the Gulf of Mexico (more than 300 miles), tropical storm impacts are rare at the site and are mostly from storm remnants. Impacts are generally restricted to flood effects from heavy rains (addressed in Subsection 2.3.1.6). From 1905 to the present, there have been 10 tropical storms within a 50-mile radius of the site. Although some of these were originally classified as hurricanes, all were classified as tropical storms when they reached the site area.

A review of the NCDC Storm Events Database for the period of January 1, 1950, through December 31, 2020, shows that there was only one tropical storm on September 16, 2004, near Roane County, and it caused minimal damage. This storm was associated with Hurricane Ivan.

2.3.1.9 Winter Storm Events The maximum reported 24-hour snowfall depth at Knoxville (Reference 6) reported during the 61-year period of record was 23.3 inches in February 1960. Snowfall records for stations around the site (Table 2.3-1) show a maximum 24-hour snowfall of 20 inches (March 1993) at Chattanooga (Reference 12).

Frost penetration depth is important for protection of water lines and other buried structural features that are subject to freeze damage. The extreme depth is slightly less than 19.6 inches based on Figure 13 in Reference 24.

2.3.1.10 Ice Storms Estimations of regional glaze probabilities have been made by Tattelman and Gringorten (Reference 25).

For Region V, which contains Tennessee, storms with ice greater than or equal to 1 inch of ice occurred five times in 50 years and storms with ice greater than or equal to 2 inches of ice occurred two times in 50 years.

For ice storms with wind gusts greater than or equal to 44.7 mph, the estimated ice thickness is less than 1 inch for 25- and 50-year return periods, and 1.4 inches for a 100-year return period.

Based on the data provided in American Society of Civil Engineers (ASCE) Standard No. 7-10 (Reference 26), Figure 10.4-2, the specification for calculating the ice load on a structural element is: the 500-year mean recurrence interval of uniform ice thickness due to freezing rain for Roane County is 0.751 inches with a concurrent 3-second wind gust of 30 mph.

For glaze ice, the point probabilities for ice thicknesses are about 0.20 for greater than or equal to 0.5 inches and 0.36 for greater than or equal to 0.25 inches. These probabilities correspond to recurrence intervals of once in 5 years and once in 3 years, respectively. Glaze ice thicknesses less than or equal to 0.5 inches generally results in little structural damage. However, storms that produce these Kairos Power Hermes Reactor 2-50 Revision 1

Preliminary Safety Analysis Report Site Characteristics From the National Oceanic and Atmospheric Administration (NOAA), Hydrometeorological Report No. 53, (Reference 32), the 48-hour Probable Maximum Winter Precipitation (PMWP) (January through March) for a 10-square-mile area is estimated to be 23.5 inches by logarithmic interpolation. The March PMWP was utilized since the historically highest snowpack occurred in March 1993. The 48-hour PMWP is equivalent to the Extreme Liquid Winter Precipitation Event.

2.3.1.12 Design Basis Dry- and Wet-Bulb Temperatures This section provides ambient temperature and humidity statistics to establish heat loads for the design of normal the plant heat sink systems, post-accident containment heat removal systems, and plant heating, ventilating, and air conditioning systems. The following parameters have been calculated:

x Maximum dry-bulb temperatures at 0.4 percent, 2 percent, and 5 percent annual exceedance levels x Mean coincident wet-bulb temperatures at 0.4 percent, 2 percent, and 5 percent annual exceedance levels x Maximum non-coincident wet-bulb temperature at 0.4 percent annual exceedance levels x Minimum dry-bulb temperature at 0.4 percent, 1 percent, and 2 percent annual exceedance levels x 100-year return maximum dry-bulb, mean coincident wet-bulb, maximum non-coincident wet-bulb, and minimum dry-bulb temperatures Meteorological data from the Chattanooga Lovell Airport was obtained from the NOAA NCDC for use in determining extreme values. This data is the best available long-term data record because the data record for Oak Ridge is incomplete (data gap between 1985 and 1999).

Annual exceedance and 100-year maximum values for dry-bulb and wet-bulb temperatures of 0.4 percent, 2 percent, and 5 percent will be used in the design basis for safety-related and non-safety-related ventilation and heat removal system design for the Hermes site.

Sixty-six years of raw climatological data were obtained from NOAA/NCDC for the Chattanooga Lovell Airport. This data set contains hourly measurements of dry-bulb and dewpoint temperature records, amongst several other meteorological variables. This data was used to calculate the various exceedance temperatures. Results of the ambient design temperature analysis are presented in Table 2.3-3 to Table 2.3-5. Similar evaluations were performed using the NOAA/NCDC data for Knoxville. Because the Chattanooga data produced more conservative (higher temperature) results, these results are used as the design basis.

Monthly climate data for 2017 were found in the American Society of Heating, Refrigerating, and Air Conditioning Engineers (ASHRAE) Handbook - Fundamentals (Reference 33) for Chattanooga Airport and for the Oak Ridge Automated Surface Observing System station. The monthly design dry bulb temperatures with mean coincident wet bulb temperatures and the monthly design wet bulb temperatures are presented in Table 2.3-6 to Table 2.3-9, for annual exceedances listed above. The Chattanooga data produces slightly more conservative results than the Oak Ridge data, but both data sets are very similar, so Chattanooga data are used as the design basis.

2.3.1.13 Meteorological Data for Evaluating Ultimate Heat Sink The Hermes Reactor does not rely on an external water source as its ultimate heat sink (UHS), but rather uses direct to air heat rejection. Therefore, considerations of evaporation and drift loss of water, minimum water cooling, and the potential for water freezing in a UHS water storage facility are not applicable.

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Preliminary Safety Analysis Report Site Characteristics 2.3.2.5 Atmospheric Moisture Long-term relative humidity and absolute humidity data for Knoxville and Oak Ridge are presented in Table 2.3-16. Short-term humidity data based on measurements at the ORR meteorological Tower L are summarized in Table 2.3-17. The humidity data among the three sites (Knoxville, Oak Ridge, and the site) are compared in Table 2.3-16 and Table 2.3-17. site data are comparable to the long-term data. The dew points and humidity data are a little higher for the 2018-2019 Tower L period than for the longer-term Knoxville and Oak Ridge data periods.

2.3.2.6 Precipitation The summary provided in this subsection is taken in large part from the Clinch River Nuclear Site planning documents due the proximity of that project to the site.

Rain Hourly precipitation observations are available from the Oak Ridge NWS station (approximately 12 miles northeast of the site). The long-term observations from the precipitation data from Oak Ridge (Reference 15) are presented in Table 2.3-18. Precipitation falls an average of about 125 days per year, and the normal annual precipitation is nearly 51 inches. The maximum monthly rainfall has ranged from about 7 inches to just over 19 inches. The minimum monthly amount was a trace in October 1963. The maximum in 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> was 7.48 inches in August 1960. With the exception of late-summer/early-autumn (which are slightly drier), precipitation is fairly uniformly distributed through the year. July and March are normally the wettest months of the year.

Precipitation data from the nearby Towers J and L (Reference 8, Table 2.3-19) indicate more than normal precipitation during 2018 and 2019. Maximum rainfall, estimated by statistical analysis of regional precipitation data, is given in Table 2.3-20 for return periods of 1 to 100 years and for rainfall durations from 5 minutes to 10 days. These data were taken from NOAA Atlas 14, Volume 2, Version 3 (Reference 38).

The PMP, sometimes called maximum possible precipitation, for a given area and duration is the depth that is expected to possibly be reached, but not exceeded, based on historical meteorological observations. For the site area, using a 100-year return period, the PMP for 6, 12, 24, and 48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br /> is 4.75.0, 5.76.0, 6.8, and 8.30 inches, respectively (see Table 2.3-20). Approximately 49 thunderstorms occur in a typical year (Reference 14). Thunderstorm activity is most predominant in the spring and summer seasons, and the maximum frequency of thunderstorm days is normally in July (Table 2.3-18).

Snow Appreciable snowfall is relatively infrequent in the area. Snowfall data are summarized in Table 2.3-21 for Knoxville and Oak Ridge. Normal annual snowfall has ranged from about 6.5 inches at Knoxville to about 11 inches at Oak Ridge. Generally, significant snowfalls are limited to December through March.

Respective 24-hour maximum snowfalls have been 18 and 12 inches at Knoxville and Oak Ridge.

Precipitation Wind Roses Figure 2.3-23 shows composite 2018-2019 precipitation and wind directions (vector) data from Tower L.

Precipitation is most often associated with wind directions from SSW-SW, corresponding to the predominant wind flow direction sectors. There is a secondary maximum with wind directions from NE-ENE.

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