ML24057A387

Hermes 2 General Audit Questions 5.2-13, 5.2-14, and 5.2-15

ML24057A387
Person / Time
Site:	Hermes  File:Kairos Power icon.png
Issue date:	02/26/2024
From:	Michael Orenak NRC/NRR/DANU/UAL1
To:	Gardner D, Peebles D Kairos Power
References
EPID L-2023-CPS-0000
Download: ML24057A387 (1)

Text

From: Michael Orenak To: Drew Peebles; Darrell Gardner Cc: Pravin Sawant; Matthew Hiser; Candace de Messieres; William Jessup

Subject:

Hermes 2 Audit Questions 5.2-13, 5.2-14, and 5.2-15 Date: Monday, February 26, 2024 5:19:00 PM

Darrell and Drew,

Below is the tenth 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 post answers to these questions on the Kairos electronic reading room, but no written answers are requested by the NRC staff at this time.

PSAR Section RequestRequest/Question Number 5.2, Intermediate 5.2-13 Preliminary safety analysis report (PSAR) Section1.2.3, Design Features and Design Bases, provides Heat Transport the following definition for safety-related structures, System systems, and components (SSCs):

Those SSCs that are relied upon to remain functional during normal operating conditions and during and following design basis events to assure:

The integrity of the portions of the reactor coolant boundary relied upon to maintain coolant level above the active core (see below);

The capability to shut down the reactor and maintain it in a safe shutdown condition; or The capability to prevent or mitigate the consequences of accidents which could result in potential exposures exceeding the limits set forth in 10 CFR 100.11.

PSAR Table 3.6-1, Structures, Systems, and Components, states that the intermediate heat exchanger (IHX) is non-safety related. Given that the IHX tubes are relied upon to separate Flibe in the primary heat transport system from water/steam in the intermediate heat transport system (IHTS) following a postulated superheater tube leak or rupture event, discuss how the IHX was evaluated against the three criteria that make up the definition of safety-related SSCs. In particular, discuss whether the IHX is relied upon to assure the capability to prevent or mitigate the consequences of accidents following design basis events such as the superheater tube leak or rupture event.

5.2, Intermediate 5.2-14 PSAR Table 3.6-1 states that the IHX and superheater Heat Transport are seismically designed to local building codes and System are non-safety related. Given that none of the components of the IHTS, other than the rupture disks, are designed to withstand a design basis earthquake (DBE), discuss the effects of a DBE on the IHTS SSCs and any potential Flibe water-interactions that could result from failures caused by a DBE.

5.2, Intermediate 5.2-15 In a postulated superheater tube leak or rupture event, Heat Transport discuss when the intermediate salt pumps would be System secured in the event progression. State whether the pump trips are accomplished through automatic means by an instrumentation and control system (e.g.,

reactor protection system) or by manual operator action. If the pumps are tripped automatically, state what conditions are used to initiate the pump trips (e.g., sensed pressure at the rupture disk). For manual operator action, state what indications the operator would be expected to acknowledge prior to initiating the pump trips.

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.

Mike

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