ML22193A253

Univ. of California-Davis - Summary of the Analysis of Changes Made to the MNRC Emergency Plan Under the Provisions of 10 CFR 50.54q

ML22193A253
Person / Time
Site:	University of California-Davis
Issue date:	07/12/2022
From:	Frey W McClellan Nuclear Research Center
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
Download: ML22193A253 (1)

Text

UNIVERSITY OF CALIFORNIA, DA VIS

BERKELEY

• DA VIS

• IRVINE

• LO S ANGELES

• MER CED

• RIVERSIDE

• SAN DIEGO

• SAN FRANCISCO ) SANT A BARBARA

• SANT A CRUZ ; _________ _

McClellan Nuclear Research Center UN IVERSITY OF CALIFORNIA Davis (916)-614-6200

July 12th, 2022

US Nuclear Regulatory Commission 11555 Rockville Pike MS 12-D3 Rockville, MD 20852-2738

SUBJECT:

Summary of the Analysis of Changes Made to the MNRC Emergency Plan Under the Provisions of 10 CFR 50.54q.

During the facility's current relicensing effort with the US NRC, a new accident scenario was identified that required an update to the MNRC emergency plan. This scenario involves a rapid (~1 hour) complete loss of coolant accident (LOCA). When the MNRC reactor was previously operated at 1.5 MW or above, the LOCA accident focused on preventing the overheating of the core from decay heat. This resulted in the MNRC Emergency Core Cooling System (ECCS), which would provide the required cooling during this event to prevent fuel damage. The MNRC is currently administratively limited to 1.0 MW in anticipation of the 1.0 MW steady state power limit requested in the new license. During the relicensing review process the concern arose that during a complete LOCA (while there is no concern of fuel overheating) the skyshine radiation from the uncovered core will result in prolonged doses outside of the MNRC 's boundary in excess of 10 CFR 20 limits. To address this scenario, the old ECCS system has been repurposed as the Core Reflooding System (CRS), though no physical changes need to be made to the system.

The emergency plan has been updated under the provisions of 10 CFR 50.54 q to include operator response to a complete LOCA, specifically on the use of the CRS. Because the previous emergency plan did not address the mitigation of this scenario at all, this change does not represent a reduction of the effectiveness of the emergency plan and therefore does not require review and approval from the NRC. This was the only change made to the emergency plan.

If there are any questions or concerns over the changes made to the emergency plan or this summary of the analysis of the change in effectiveness of the plan, please contact me directly.

I declare under penalty of perjury that the foregoing is true and correct executed on July 121\\ 2022.

Sincerely,

'.U,V~

Wesley Frey PhD Facility Director