ENS 46203
ENS Event | |
|---|---|
16:40 Aug 24, 2010 | |
| Title | Essential Service Water Placed in a Line-Up That May Have Prevented Its Safety Function |
| Event Description | At 1140 [CDT] on August 24th, Unit 2 received Essential Service Water (SX) discharge header pressure low and SX strainer delta pressure high alarms indicative of high flow. At the time, a 2B SX ASME surveillance was in progress which involved field operations by Equipment Operators (EO's). At the time of the event, SX discharge header pressure dropped to 65 psig, less than the 89 psig necessary for operability. The Control Room responded by directing the EO's to restore SX discharge header pressure, which was promptly restored.
The 2B SX ASME surveillance sets initial conditions prior to data collection. The surveillance has the total SX flow be adjusted to 24000 gpm via the U2 Component Cooling Water (CC) heat exchanger outlet throttle valve, 2SX007. The subject flow was intended to be measured via an installed ultrasonic flow gauge 2FE-SX147. The EO's, instead used the U2 CC heat exchanger flow gauge 2FE-SX031. As a result, in an attempt to achieve 24000 gpm through the U2 CC heat exchanger, total SX flow exceeded the 24000 gpm since the U2 CC heat exchanger is but one of many loads the 2B SX pump is serving. For the 5 minutes described above, the SX system was in a lineup that may have prevented it to fulfill its safety function and placed Unit 2 in a potentially unanalyzed condition. This condition is still being evaluated. Site Engineering has determined no runout conditions existed. The licensee notified the NRC Resident Inspector.
The evaluation of the condition has been completed. Based on Essential Service Water (SX) system flow model runs performed, the conditions that existed at the time of the low SX header pressure would have resulted in low flow supplied to multiple safety related components. However, the safety function to provide necessary cooling to required safety-related safe shutdown equipment would have been met under design basis conditions with the auto-start of the 2A SX pump. Therefore, this did not result in a condition that could have prevented fulfillment of a safety function or in an unanalyzed condition that significantly degraded plant safety. Therefore, ENS notification 46203 is being retracted. The licensee notified the NRC Resident Inspector. Notified the R3DO (Daley). |
| Where | |
|---|---|
Braidwood  Illinois (NRC Region 3) | |
| Reporting | |
| 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident | |
| Time - Person (Reporting Time:+3.37 h0.14 days <br />0.0201 weeks <br />0.00462 months <br />) | |
| Opened: | James Muraida 20:02 Aug 24, 2010 |
| NRC Officer: | Howie Crouch |
| Last Updated: | Oct 19, 2011 |
| 46203 - NRC Website
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Unit 2 | |
|---|---|
| Reactor critical | Critical |
| Scram | No |
| Before | Power Operation (100 %) |
| After | Power Operation (100 %) |
Braidwood with 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident, 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition | |
WEEKMONTHYEARENS 519592016-05-25T19:15:00025 May 2016 19:15:00
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