05000331/LER-2014-004
| Duane Arnold Energy Center | |
| Event date: | 05-30-2014 |
|---|---|
| Report date: | 07-25-2014 |
| Reporting criterion: | 10 CFR 50.73(a)(2)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident |
| Initial Reporting | |
| ENS 50154 | 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident |
| 3312014004R00 - NRC Website | |
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I. Description of Event:
On May 30, 2014, at 1043, while operating at 100% power, during the performance of a routine Technical Specification (TS) required Surveillance Test Procedure (STP), the 'A' side High Pressure Coolant Injection (HPCI) (BG) isolation logic was activated. The logic activation occurred while attempting to block open contacts of HGA relay E41A-K43, HPCI Auto Isolation Logic Steam Line High Differential Pressure. The root cause of this event was the design of the HGA relay makes the act of installing relay blocks very difficult and prone to inadvertent actuation. On May 30, 2014, at 1209, HPCI was returned to operable status after resetting the isolation logic and returning the system to standby readiness condition.
This resulted in an 8 hour9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> reportable event. The Resident Inspector was notified, and Event Notification Number 50154 was made pursuant to 10 CFR 50.72(b)(3)(v)(D) due to a condition at the time of discovery that prevented the fulfillment of the HPCI safety function.
There were no radiological releases associated with this event. There were no other structures, systems or components inoperable at the start of this event that contributed to the event.
II. Assessment of Safety Consequences:
There were no actual safety consequences associated with this event; the potential safety consequences were minimal. During the time period that HPCI was inoperable, all other Emergency Core Cooling Systems were fully capable of performing their safety functions.
This event did result in a safety system functional failure.
Cause of Event:
A Root Cause Evaluation was completed. The evaluation identified the following root cause:
The design of the HGA relay makes the act of installing relay blocks very difficult, and prone to inadvertent actuation.
IV. Corrective Actions:
On May 30, 2014, at 1209, HPCI was returned to operable status after resetting the isolation logic and returning the system to standby readiness condition.
The following actions will be taken to address the root cause of this event:
Eliminate the use of HGA relay blocks in all STPs where inadvertent actuation could cause an un- planned shutdown, LCO, system unavailability, or a reportable event.
V. Additional Information:
Previous Similar Occurrences:
A review of DAEC Licensee Event Reports from the past 5 years identified one similar occurrence, reference LER 2012-004.
EIIS System and Component Codes:
BG - High Pressure Core Spray System (BWR) Reporting Requirements:
This event is being reported as an event or condition that could have prevented the fulfillment of the safety function of structures or systems that are needed to mitigate the consequences of an accident, 10CFR50.73(a)(2)(v)(D).