ML23006A111
| ML23006A111 | |
| Person / Time | |
|---|---|
| Site: | Hermes File:Kairos Power icon.png |
| Issue date: | 01/14/2023 |
| From: | Heiser M NRC/NRR/DANU/UAL1 |
| To: | Gardner D, Peebles D Kairos Power |
| References | |
| Download: ML23006A111 (1) | |
Text
From:
Matthew Hiser To:
Drew Peebles; Darrell Gardner Cc:
Benjamin Beasley; Jeffrey Schmidt; Edward Helvenston; Samuel Cuadrado de Jesus; Meg Audrain; Alexander Chereskin
Subject:
Hermes PSAR General Audit Questions PSAR Section 6.3 Date:
Wednesday, December 14, 2022 4:20:00 PM Hi Darrell and Drew,
The staff is completing its writing of its safety evaluation Chapter 6 and in reviewing PSAR Section 6.3 has a couple of additional questions. The staff would like to have a meeting with Kairos, as part of the general audit, to discuss the items below:
- 1. PSAR Chapter 4 was revised to note a maximum design temperature for the reactor vessel of 750 °C. PSAR Section 6.3.3 indicates the DHRS components will be designed to operate up to 800 °C, while PSAR Table 6.3-3 indicates a thimble design temperature of 1500 °F (~816 °C).
- a. Please confirm on the docket that the design of the DHRS will be consistent with ASME BPVC Section III, Division 5 such that the Chapter 6 DHRS design temperature is consistent with the revision to the reactor vessel temperature in Chapter 4.
- 2. On September 1, 2022, Kairos provided a docketed response (KP-NRC-2209-003, ML22244A235) to an audit question related to the DHRS system, in which Kairos described the plans for DHRS qualification testing.
- a. In KP-NRC-2209-003, Kairos stated Qualification testing for the safetyrelated portion of the DHRS will be defined in a test plan that includes appropriate acceptance criteria and demonstrates the system reliability and adequacy of performance under conditions that simulate the most adverse design basis conditions. While working to complete the SER input for Chapter 6, the staff noted several additional topics related to materials and mechanical performance of the DHRS system that could be addressed through the planned qualification testing:
- i. Thermal shock effects on material properties and component integrity from stress and thermal cycling during evolution from 550 °C to 100 °C upon DHRS startup at threshold power, ii. Flow-induced vibration effects on DHRS components during evolution from 550 °C to 100 °C upon DHRS startup at threshold power, iii. Metal fatigue effects due to repeated stress and thermal cycling during evolutions from 550 °C to 100 °C upon DHRS startup at threshold power.
Please address on the docket whether these topics will be addressed by the planned DHRS qualification testing or provide justification why testing is not needed for these items.
Please let us know when we can meet with Kairos to discuss these topics. The staff has availability on Friday, December 16, Tuesday, December 20 and Wednesday, December 21.
Thanks!
Matt
Matthew Hiser Senior Project Manager Advanced Reactor Licensing Branch 1 (UAL1)
Division of Advanced Reactors and Non-Power Production and Utilization Facilities (DANU)
Office of Nuclear Reactor Regulation (NRR)
US Nuclear Regulatory Commission Phone: 301-415-2454 l Office: OWFN 6C53 Matthew.Hiser@nrc.gov