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The following information was provided by … The following information was provided by the University of Missouri-Columbia Research Reactor (MURR) via phone and email:</br>During a normal reactor start up on 5/23/2023, while still approaching criticality, reactor power peaked slightly above 100 kW with a single control blade 1.4 inches below the other three control blades. This is a violation of Technical Specification (TS) 3.2.b which states that above 100 kW, the reactor shall be operated so that the maximum distance between the highest and lowest shim blade shall not exceed 1 inch.</br>As part of a normal reactor startup, three control blades were at 23 inches and the core was approaching criticality. As the fourth control blade was being pulled to the bank height, the Lead Senior Reactor Operator stated power was approaching 100 kW, alerting the Reactor Operator to the TS of no more than a one-inch height differential between control blades. Reactor power slowly increased. The Reactor Operator stopped shimming out on Control Blade 'A' and shimmed the other three rods inward individually to stop the power rise. He continued to then pull Control Blade 'A' out while leveling power by shimming the other three rods in. The control room continued the startup. No other issues occurred during the approach to full power (10 MW).</br>After the startup, the Lead Senior Reactor Operator raised a concern that it was possible power peaked slightly above 100 kW with Control Blade 'A' at 1.4 inches below the other three control blades. Strip charts confirmed power peaked at 103.5 kW during this time. Total duration in this unapproved control blade configuration was less than one minute.</br>The Reactor Manager was informed of the problem, and he informed the Interim Facility Director. MURR Licensee Event Report (LER) 13-03 discusses a similar event. Calculations performed for that event show that a control blade can differ by as much as 4 inches from the bank with no adverse effects to the core. MURR reactor operations were continued.</br>MURR will follow up with an LER to address this issue.llow up with an LER to address this issue.
13:45:00, 23 May 2023 +
56,534 +
18:08:00, 23 May 2023 +
13:45:00, 23 May 2023 +
The following information was provided by … The following information was provided by the University of Missouri-Columbia Research Reactor (MURR) via phone and email:</br>During a normal reactor start up on 5/23/2023, while still approaching criticality, reactor power peaked slightly above 100 kW with a single control blade 1.4 inches below the other three control blades. This is a violation of Technical Specification (TS) 3.2.b which states that above 100 kW, the reactor shall be operated so that the maximum distance between the highest and lowest shim blade shall not exceed 1 inch.</br>As part of a normal reactor startup, three control blades were at 23 inches and the core was approaching criticality. As the fourth control blade was being pulled to the bank height, the Lead Senior Reactor Operator stated power was approaching 100 kW, alerting the Reactor Operator to the TS of no more than a one-inch height differential between control blades. Reactor power slowly increased. The Reactor Operator stopped shimming out on Control Blade 'A' and shimmed the other three rods inward individually to stop the power rise. He continued to then pull Control Blade 'A' out while leveling power by shimming the other three rods in. The control room continued the startup. No other issues occurred during the approach to full power (10 MW).</br>After the startup, the Lead Senior Reactor Operator raised a concern that it was possible power peaked slightly above 100 kW with Control Blade 'A' at 1.4 inches below the other three control blades. Strip charts confirmed power peaked at 103.5 kW during this time. Total duration in this unapproved control blade configuration was less than one minute.</br>The Reactor Manager was informed of the problem, and he informed the Interim Facility Director. MURR Licensee Event Report (LER) 13-03 discusses a similar event. Calculations performed for that event show that a control blade can differ by as much as 4 inches from the bank with no adverse effects to the core. MURR reactor operations were continued.</br>MURR will follow up with an LER to address this issue.llow up with an LER to address this issue.
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