ML25050A611
| ML25050A611 | |
| Person / Time | |
|---|---|
| Site: | University of Utah |
| Issue date: | 02/18/2025 |
| From: | Allison A, Goodell E Univ of Utah, Salt Lake City |
| To: | Office of Nuclear Reactor Regulation, Document Control Desk |
| References | |
| IR 2024201 | |
| Download: ML25050A611 (1) | |
Text
February 18th, 2025 From: Dr. Edward Goodell, Reactor Facility Director University of Utah TRIGA Reactor Facility (Docket: 50-407) 110 Central Campus Drive, Room 2000, Salt Lake City, UT 84112 To: Document Control Desk, US NRC, Washington, D.C. 20555 Director, Office of Enforcement, US NRC, Washington, DC 20555-0001 Tony Brown, Chief of Non-Power Production and Utilization Facility Oversight Branch Jessica Lovett, Project Manager for The University of Utah
References:
Ref (1) NRC Letter dated January 21st, 2025: UNIVERSITY OF UTAH - U.S. NUCLEAR REGULATORY COMMISSION ROUTINE INSPECTION REPORT NO. 05000407/2024201 AND NOTICE OF VIOLATION (ADAMS Accession No: ML24261B239)
SUBJECT:
REPLY TO A NOTICE OF VIOLATION
Dear Director,
Office of Enforcement, United States Nuclear Regulatory Commission, The University wishes to respectfully contest the notice of violation outlined in Ref (1). In accordance with Ref (1), the University of Utah TRIGA Reactor (UUTR) facility replies with the following comments:
(1) Basis for disputing the violation or severity level:
TS 5.2 speci"es, A reactor tank water level alarm shall be provided to indicate loss of coolant if the water level drops 15.5 inches from the top of the reactor tank. TS 3.3 speci"es, The reactor tank water level alarm shall indicate loss of coolant if the tank water level decreases greater than 15.5 inches from the top of the UUTR water tank. As mentioned in Ref (1), UUTR satis"es these requirements by using a "oat sensor with a setpoint at 15.5 inches. If UUTR moved this sensor, it would violate technical speci"cations and reduce reactor safety by permitting rod withdrawal since the setpoint of the pool low water level scram, which is connected to the "oat sensor, would be changed. Therefore, UUTR maintained the "oat sensor at 15.5 inches to continue performing its function of locking in a low water level SCRAM while the water level was below 15.5 inches.
TS 3.2.3 speci"es a Limiting Condition for Operation as follows:
Reactor.tank.water.level: The UUTR pool water must have a speci"c water level to avoid the reactor scram. The distance from the top of the reactor tank to the surface of the pool water must be less than 15.5 inches.
As mentioned in Ref (1), UUTR removed sufficient fuel elements to satisfy the de"nition of Reactor.
Secured?.signifying there was insufficient "ssile material in the reactor to attain criticality under optimum available conditions of moderation and re"ection. UUTR Technical Speci"cations does
not have a water level requirement associated with a shutdown/secured reactor. Therefore, UUTR concluded with a 50.59 evaluation that it may lower the reactor tank water level beyond 15.5 inches after the reactor was secured.
Ref (1) states from TS 4.3, The objective of the channel check is to assure that the water level monitoring system is operating and to verify appropriate settings. TS 4.3 does not specify that the water level monitoring system needs to be a "oat sensor. Ref (1) fails to mention that UUTRs 50.59 evaluation discussed the use of a submersible area radiation monitor (ARM) with a low setpoint of 0.5 mR/hr as a water level monitoring system.
Understanding the necessity to maintain personnel safety in compliance with 10 CFR 20 radiation limits, the target water level UUTR desired to maintain was sufficient to ensure no substantial radiation above background was escaping the reactor tank water surface. UUTR accessed this water level by lowering the tank ARM directly above the reactor core until it was at the onset of detectable radiation from the reactor. If water level lowered below the tank ARM, the reduction in tank water shielding would cause the tank ARM to alarm once the low setpoint of 0.5 mR/hr was reached. The position of the ARM was gradually lowered deeper in the tank as short-lived nuclides in the reactor decayed and as fuel elements were removed from the reactor tank. Eventually, the active leak stopped as water level lowered to 10.3 feet from the top of the tank. However, UUTR staff continually adjusted the tank ARM position to function as a water level monitoring system during tank unloading to ensure it was accurately at the onset of detectable radiation from the reactor.
Similar to the "oat sensor located 15.5 inches from the top of the tank, the tank ARM has an alarm in the control room and sends a signal to university dispatch providing a timely warning so that corrective action can be initiated. The tank ARM with a setpoint of 0.5 mR/hr was checked monthly during the period water level was maintained lower than 15.5 inches with reactor fuel still in the reactor tank which satis"ed the monthly surveillance requirement of TS 4.3 (1).
The Tank ARM functioning as a water level monitoring system successfully performed the design function of indicating an unexpected loss of shielding water while water level was lowered below 15.5 inches with reactor fuel still in the tank. Therefore, UUTR staff do not believe a license amendment was necessary, and the change discussed could be made under 10 CFR 50.59.
(2) Corrective steps that have been taken and the results achieved:
UUTR completed removing all TRIGA fuel elements along with all other components from the reactor tank on September 27th, 2024 in preparation for reactor tank inspection and repairs.
Following removal of all reactor fuel and the startup source, the tank ARM previously used for the water level monitoring system was removed from the reactor tank and returned to its normal setpoint of 10 mR/hr as part of the area radiation monitoring system.
(3) Corrective steps that will be taken:
Once reactor tank repairs are complete, UUTR will perform a tank integrity test by "lling the reactor tank above the "oat sensor low water level alarm setpoint of 15.5 inches. UUTR then intends to maintain water level above the "oat sensor performing as a water level monitoring system for all subsequent maintenance/operations with UUTR.
(4) Date when full compliance will be achieved:
UUTR staff affirms, to the best of its knowledge, it is in full compliance with all requirements associated with UUTR license. We continue to verify monthly that the low water level alarm located at 15.5 inches is operational to ensure it will perform its intended function when water level is returned above 15.5 inches for subsequent UUTR operation.
Dr. Edward Goodell, Reactor Facility Director Andrew Allison, Reactor Supervisor