ENS 43602
ENS Event | |
|---|---|
05:00 Aug 27, 2007 | |
| Title | One Channel of Low Main Steam Line Pressure Signal Mistakenly Removed from Service for 33 Minutes |
| Event Description | On 8/27/07 at approximately 12:05, during performance of STP 3.3.6.1-02 step 7.7.2 the jumper was installed on contacts 1 and 2 of relay A71B-K4A PCIS TRIP CHANNEL A1 A MAIN STEAM LINE LO PRESSURE. The jumper should have been installed on contacts 1 and 2 of relay A71B-K4C PCIS TRIP CHANNEL A2 C MAIN STEAM LINE LO PRESSURE.
The incorrectly installed jumper on contacts 1-2 of relay A71B-K4A resulted in the channel A1 not being able to trip on a low main steam line pressure signal of 850 psig (PS1014) thus making the function of PS1014 inoperable. At the same time PS1016 was being tested for channel A2 thus making the function for pressure switch PS1016 inoperable. Per Technical specification 3.3.6.1 'Primary Containment Isolation Instrumentation' function 1b 'Main Steam Line pressure - Low' with both PS1014 and PS1016 inoperable, the tripping capability for channel A for Main steam Line Pressure - Low would be lost. This would be a automatic function with isolation capability not maintained per TS 3.3.6.1 condition B. Required action B.1 requires isolation capability to be restored in 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br />. The I&C techs entered the AOT time for PS1016 at 11:32 AM and exited the AOT at 12:05 PM. Therefore, the isolation capability was lost for 33 minutes of the 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br />. There was no violation of Technical Specification 3.3.6.1 function 1b. This event is reportable under 10 CFR 50.72(b)(3)(v), 'Any event or condition that alone at the time of discovery could have prevented the fulfillment of the safety function of structures or systems that are needed to (D) Mitigate the consequences of an accident. The licensee notified the NRC Resident Inspector.
An UFSAR review has determined that the Main Steam Line Low Pressure isolation is intended to mitigate a transient event. Specifically, the isolation is a safety feature intended to mitigate the consequences of an EHC Pressure Regulator Failure - Open. This transient is not a Design Basis Accident (DBA). Therefore this event resulted in a loss of a Safety Feature, not a loss of a Safety Function. This event is not reportable under 10CFR50.72(b)(3)(v)(D) because the event did not result in a condition that would have prevented the fulfillment of a safety function needed to mitigate the consequences of an accident. Notified the R3DO (Hills). The licensee notified the NRC Resident Inspector. |
| Where | |
|---|---|
Duane Arnold  Iowa (NRC Region 3) | |
| Reporting | |
| 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident | |
| Time - Person (Reporting Time:+15.43 h0.643 days <br />0.0918 weeks <br />0.0211 months <br />) | |
| Opened: | Ellis Vann 20:26 Aug 27, 2007 |
| NRC Officer: | Pete Snyder |
| Last Updated: | Oct 26, 2007 |
| 43602 - NRC Website
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Unit 1 | |
|---|---|
| Reactor critical | Critical |
| Scram | No |
| Before | Power Operation (100 %) |
| After | Power Operation (100 %) |
Duane Arnold with 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident | |
WEEKMONTHYEARENS 528812017-08-01T14:34:0001 August 2017 14:34:00
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