ML23324A117

Hermes 2 General Audit Questions 2.1-1, 2.1-2, 2.2-1 Through 4, 2.5-1, 7.1-1, 7.2-1, and 7.2-2

ML23324A117
Person / Time
Site:	Hermes  File:Kairos Power icon.png
Issue date:	11/20/2023
From:	Michael Orenak NRC/NRR/DANU/UAL1
To:	Peebles D, Gardner D Kairos Power
References
EPID L-2023-CPS-0000
Download: ML23324A117 (1)

Text

From:

Michael Orenak To:

Darrell Gardner; Drew Peebles Cc:

Matthew Hiser; Edward Helvenston; Pravin Sawant; William Jessup; Candace de Messieres

Subject:

Third Set of Hermes 2 Audit Questions (2.1-1, 2.1-2, 2.2-1 through 4, 2.5-1, 7.1-1, 7.2-1, 7.2-2)

Date:

Monday, November 20, 2023 10:51:00 AM Darrell and Drew,

Below is the third set of audit questions for the Hermes 2 General Audit. The NRC staff would like to have a discussion regarding these questions when Kairos is ready. Kairos is welcome to provide written answers in the eRR prior to the audit meeting if desired, but no written responses are requested at this time by the NRC.

PSAR Section Request Number Request/Question 2.1, Geography and Demography 2.1-1 In Hermes 2 PSAR Table 2.1-2, please provide the base year used for population projection. Compared to Hermes 2 PSAR Table 2.1-1, it seems 2010 is used for Morgan County and 2020 is used for Roane County. In addition, there is a significant population increase at the 3-to-5 mile band for all years compared to Hermes 1 PSAR Table 2.1-2. Please discuss this discrepancy.

2.1, Geography and Demography 2.1-2 Hermes 2 PSAR Section 2.1.1.1 does not mention Hermes 1 as a prominent man-made feature within 5 miles. Please discuss why Hermes 1 is not included.

2.2, Nearby Industrial, Transportation, and Military Installations 2.2-1 The effects of Hermes 1 accidents on the safe operation of the Hermes 2 facility are not discussed in Hermes 2 PSAR Section 2.2.3. For example, the Hermes 1 facility is planned to include storage of 21,555 gallons of diesel fuel in one onsite fuel tank.

The overpressure on Hermes 2 from a potential explosion of this tank is likely negligible, but no analysis is provided regarding other potential hazards from this storage tank (e.g., fire, smoke, and other BLEVE [boiling liquid expansion vapor explosion] hazards).

2.2, Nearby Industrial, Transportation, and Military Installations 2.2-2 In Hermes 2 PSAR Table 2.2-1, the Ultra Safe Nuclear Corporation Pilot Fuel Manufacturing Facility is 0.8 mi away from the Hermes 2 facility. The mention of this facility is new in the Hermes 2 PSAR, as compared to the information provided in the Hermes 1 construction permit application.

The table notes that accidents at this facility are not expected to affect the Hermes 2

facility without any discussion or bases for this assertion. Please provide a discussion or justification for this note.

2.2, Nearby Industrial, Transportation, and Military Installations 2.2-3 In Hermes 2 PSAR Table 2.2-1, the TRISO-X Fuel Facility is 2.4 mi away from the Hermes 2 facility. The mention of this facility is new in the Hermes 2 PSAR, as compared to the information provided in the Hermes 1 construction permit application.

The table does not provide any discussion of the effects of accidents at this facility on the Hermes 2 facility, if any. Please provide additional information regarding effects of accidents at the TRISO-X fuel facility on the proposed Hermes 2 facility.

2.2, Nearby Industrial, Transportation, and Military Installations 2.2-4 Regarding Table 2.2-8, the projected aircraft hazards may have new developments since the Hermes 1 construction permit application was submitted (e.g., the Oak Ridge airport project has progressed). The NRC staff desires to review the aircraft crash hazard calculation and selection of the representative aircraft for structural design.

2.5, Geology, Seismology, and Geotechnical Engineering 2.5-1 From the response to Hermes 2 General Audit question 1.5-2 (ML23300A144), the NRC staff understands that the due diligence report on geotechnical investigation for the Hermes 1 site is applicable to the Hermes 2 site. However, site characterization was expected to continue after the construction permit application review for Hermes 1.

Additionally, the strata at the overall site is inclined with a reactor foundation elevation of ~760 ft. for Hermes 1 vs. ~750 ft. for Hermes 2, and the overall site shows karst features. Therefore, significant spatial variations in subsurface geology may exist between Hermes 1 and Hermes 2. The NRC staff would like to:

a. Review the current due diligence report (irrespective of updates).

b. Understand the continuing site characterization that has happened since the submittal of the Hermes 1 construction permit application and whether this

information resulted in any refinements to the understanding of subsurface geology at the Hermes 2 site.

Chapter 7, Instrumentation and Controls 7.1-1 NUREG-1537, Part 2, Section 7.6, Control Console and Display Instruments, contains acceptance criteria that relate to human factors-related considerations, such as the readability of indications, the usability of controls, and the observability of alarms by the operator. Due to the added complexity of the proposed Hermes 2 facility using a dual-unit control room, please describe which standard(s) Kairos plans on using in the design process to ensure that these criteria from NUREG-1537 will be met in the finished design. It is reasonable for a test reactor PSAR to contain a high-level commitment to apply human factors engineering within the design of the control room to the extent necessary to ensure that these criteria will be met by the design submitted at the OL stage.

7.2, Plant Control System 7.2-1 In Hermes 1 PSAR Section 7.2.1.3, the Primary Heat Transfer Control System (PHTCS) is described as supporting the control of the heat rejection system. In the Hermes 2 PSAR, the PHTCS is no longer listed as supporting the control of the heat rejection subsystem (HRS). Please discuss what control system provides this functionality.

7.2, Plant Control System 7.2-2 Please Chapter 7 of the Hermes 2 PSAR, please discuss the Plant Control System (PCS) initiated runbacks of the reactivity control and shutdown system (RCSS),

primary salt pump (PSP), intermediate salt pump (ISP), and feedwater pumps.

Additionally, describe the impacts to the reactor protection system from the runback of these SSCs.

If you have any questions or need clarifications on the questions before the discussion, please do not hesitate to contact me. This email will be added to ADAMS and will be made public.

Michael D. Orenak, Project Manager Advanced Reactor Licensing Branch 1 (UAL1)

NRR - Division of Advanced Reactors and Non-Power Production and Utilization Facilities (DANU)

301-415-3229 Michael.Orenak@nrc.gov