ENS 54525
ENS Event | |
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05:25 Feb 14, 2020 | |
Title | Manual Reactor Scram Due to Rising Condenser Backpressure |
Event Description | At 0025 EST on February 14, 2020, Susquehanna Steam Electric Station Unit 2 reactor was manually scrammed due to rising Main Condenser backpressure caused by a loss of the Unit 2 Offgas Recombiner.
Unit 2 reactor was being operated at maximum facility output, approximately 98% RTP, when at 0012 EST, Unit 2 Recombiner 0C145 Panel Trouble and 2C198 HWC Panel Trouble alarms were received along with rising Main Condenser backpressure. Initial Main Condenser backpressure was 2.6 in HgA and was rising at approximately 0.3 HgA/min. A Recirc Lim 2 was inserted to lower reactor power and condenser backpressure continued to rise following the reduction in reactor power. A manual scram was inserted at 0025 EST by placing the Mode Switch to Shutdown when condenser backpressure rose to 6 in HgA. All control rods inserted. Reactor water level lowered to -30 inches causing Level 3 (+13 inches) isolation and partial (Division 2) Level 2 (-38 inches) isolation. No ECCS actuations occurred and RCIC initiated. The Operations crew subsequently maintained reactor water level at the normal operating band using Reactor Feed Water. No steam relief valves opened. The Reactor Recirculation Pumps remained in service. The reactor is currently stable in Mode 3. Investigation into the cause of the loss of Unit 2 recombiner is underway. The NRC Senior Resident Inspector was notified. A voluntary notification to PEMA and press release will occur. |
Where | |
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Susquehanna ![]() Pennsylvania (NRC Region 1) | |
Reporting | |
10 CFR 50.72(b)(2)(iv)(B), RPS Actuation 10 CFR 50.72(b)(3)(iv)(A), System Actuation | |
Time - Person (Reporting Time:+-1.82 h-0.0758 days <br />-0.0108 weeks <br />-0.00249 months <br />) | |
Opened: | Tom Rydzewski 03:36 Feb 14, 2020 |
NRC Officer: | Brian P. Smith |
Last Updated: | Feb 14, 2020 |
54525 - NRC Website
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Unit 2 | |
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Reactor critical | Critical |
Scram | Yes, Manual Scram |
Before | Power Operation (98 %) |
After | Hot Shutdown (0 %) |