ML20262G985
| ML20262G985 | |
| Person / Time | |
|---|---|
| Site: | 05200049 |
| Issue date: | 09/18/2020 |
| From: | Timothy Drzewiecki NRC/NRR/DANU/UART |
| To: | Oklo Power LLC |
| Shared Package | |
| ML20246G616 | List: |
| References | |
| Download: ML20262G985 (4) | |
Text
OFFICIAL USE ONLY PROPRIETARY INFORMATION September 18, 2020 OKLO AURORA - STEP 1 TECHNICAL REVIEW AUDIT
SUMMARY
MAXIMUM CREDIBLE ACCIDENT HEAT TRANSFER IN REACTOR SYSTEM APPLICANT INFORMATION Applicant: Oklo Power LLC.
Applicant Address: 230 E Caribbean Dr. Sunnyvale, CA 94089 Plant Name: Aurora Docket No.: 52-0049 Audit Location/Dates:
Audit was conducted via video conference.
Audit Entrance: August 27, 2020 Audit Exit: August 28, 2020 Audit Team Members Tim Drzewiecki Reactor Systems Engineer, Audit Team Lead, NRR/DANU/UART Boyce Travis Reactor Systems Engineer, NRR/DANU/UART Joseph Kelly Senior Reactor Systems Engineer, RES/DSS/CRAB Participating Applicant Staff Patrick Everett John Hanson Documents Audited
- MCA_audit_heat_transfer_Aug_27_2020.pdf
- ANSYS Mechanical Model :
Repository: oberon_results_archive Filename: FINAL_7wm2k_7wmk_225c_explicit_contacts_102pct_nodata.wbpz Git commit: 0f3261e Audit Activities Oklo presented on the heat transfer modelling performed using the ANSYS mechanical code with a focus on the thermal bonding between (1) the reactor cell can and heat pipe, and (2) the heat pipe and heat exchanger. The NRC noted the following:
- The key dimensions presented in Table 2-1 of the final safety analysis report (FSAR)
(( )). Hot dimensions are used in the ANSYS mechanical model. Hot dimensions are obtained by assuming the following:
OFFICIAL USE ONLY PROPRIETARY INFORMATION
OFFICIAL USE ONLY PROPRIETARY INFORMATION o ((
o ((
o ((
- Thermal bonding between the reactor cell cans and heat pipe [
] is modeled in ANSYS Mechanical (( )) with the following parameters:
o (( ]
))
o (( ))
o (( ))
o ((
))).
- Heat pipes are thermally bonded to the heat exchanger tubing ((
)) and heat exchanger tubes are modeled in ANSYS Mechanical as a homogenous material that is located in the heat exchanger region with the following parameters:
o (( ))
o (( ))
o (( ))
o ((
]
Oklo opened the ANSYS Mechanical model and guided NRC staff through the inputs specific to the thermal bonding between (1) the reactor cell and heat pipe, and (2) the heat pipe and heat exchanger. During this process, NRC staff was able to verify that the ANSYS Mechanical model used input parameters for the thermal bonding that are consistent with the description above.
The NRC staff performed simple hand calculations using the input assumptions stated by Oklo during their presentation and obtained similar values to those presented in the FSAR.
Exit Briefing An exit briefing was held on August 28, 2020. During this exit briefing, the audit team restated the purpose of the meeting, summarized the audit activities, recapped the key outcomes of the audit, and highlighted areas where additional information may be warranted.
RAIs or Potential RAIs The NRC staff identified the following areas where requests for additional information (RAIs) will be requested:
- 1. An update to the FSAR to include information on the thermal bonding between (1) reactor cell can and heat pipe, and (2) heat pipe and heat exchanger will be needed to support the safety case of the Aurora.
- 2. Evidence to validate the thermal bonding design and modeling assumptions will be needed to support the use of an innovative means to transfer heat from the fuel.
OFFICIAL USE ONLY PROPRIETARY INFORMATION
OFFICIAL USE ONLY PROPRIETARY INFORMATION Open Items The NRC staff identified information important to the safety case of the Aurora design during this audit. The NRC staff is seeking to (1) incorporate this information into appropriate licensing documentation, and (2) obtain additional information to support the thermal bonding design and modeling assumptions that support the Aurora safety case. The NRC staff plans to address these open items through the RAI process.
Deviations from Audit Plan Due to efficient communication between Oklo and the NRC staff, the lengths of the audit meetings were significantly reduced from the estimates provided in the audit plan (ADAMS Accession No. ML20225A227).
Principal Contributor: Timothy Drzewiecki, NRR Date: September 18, 2020
/RA/
Timothy Drzewiecki Reactor Systems Engineer, Audit Team Lead Advanced Reactor Technical Branch Division of Advanced Reactors and Non- Power Production and Utilization Facilities Office of Nuclear Reactor Regulation cc (Redacted copy): Distribution via list serv OFFICIAL USE ONLY PROPRIETARY INFORMATION
Package ML20246G616; Audit Summary ML20246G641(non-Public) Audit Summary ML20262G985 (Public-Redacted) *via e-mail OFFICE NRR/DANU/UART* NRR/DANU/UARL/PM* NRR/DANU/UARL/LA*
NAME TDrzewiecki JMazza SLent DATE 8/31/2020 9/1/2020 9/1/2020 OFFICE NRR/DANU/UART/BC* NRR/DANU/UARL/BC* NRR/DANU/UART*
NAME MHayes BBeasley TDrzewiecki DATE 8/28/2020 8/31/2020 9/18/2020