ENS 48595
ENS Event | |
|---|---|
18:50 Dec 14, 2012 | |
| Title | Technical Specification Required Shutdown - Control Structure Chillers Inoperable |
| Event Description | At 1350 on 12/14/2012, both Control Structure Chillers at Susquehanna were rendered inoperable. This event required entry into Tech Spec 3.0.3 for both Units. Per Susquehanna procedures, after 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br />, a power reduction must be commenced. Tech Spec 3.0.3 requires that action be taken within one hour to place the Unit in Mode 3 within 13 hours1.50463e-4 days <br />0.00361 hours <br />2.149471e-5 weeks <br />4.9465e-6 months <br /> and Mode 4 within 37 hours4.282407e-4 days <br />0.0103 hours <br />6.117725e-5 weeks <br />1.40785e-5 months <br />.
Physical power reduction commenced at 1453 for Unit 1 and 1459 for Unit 2. The 'A' Control Structure Chiller was previously inoperable for routine maintenance. The system was in service for post maintenance testing and activities were underway to swap to the opposite train to allow removal of test instrumentation and fan belt tensioning for equipment associated with the 'A' Control Structure HVAC system. At 1350, the 'B' Control Structure loop circulating pump tripped, rendering the 'B' Control Structure Chiller inoperable. This condition requires immediate entry into Tech Spec 3.0.3. Both Control Structure Chillers are inoperable and this report is being made per 10CFR50.72(b)(2)(i) as a shutdown required by Tech Specs, and 10CFR 50.72(b)(3)(v)(D), Loss of a Safety Function required to mitigate the consequences of an accident. Efforts are underway to restore at least one system to operable status in parallel with Unit shutdown activities. The licensee has notified the NRC Resident Inspector, and will be notifying the State of Pennsylvania.
On 12/14/12 at 1500 EST Susquehanna Steam Electric Station reported a shutdown had been commenced at 1453 EST for Unit 1 and 1459 EST for Unit 2 due to inoperability of both Control Structure Chillers. At 1750 EST the 'A' Control Structure Chiller was declared operable and LCO 3.0.3 was exited. Power reduction for both Units was halted at 1750 and preparations for power restoration initiated. On 12/14/12 Unit 1 power was restored to 98% at 1819 EST and Unit 2 power was restored to 98% at 1943 EST, the maximum power output possible based on grid conditions for Unit 1 and thermal limits for Unit 2. The licensee has notified the NRC Resident Inspector. R1DO (Holody) notified. |
| Where | |
|---|---|
Susquehanna  Pennsylvania (NRC Region 1) | |
| Reporting | |
| 10 CFR 50.72(b)(2)(i), Tech Spec Required Shutdown 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident | |
| LER: | 05000387/LER-2012-010 |
| Time - Person (Reporting Time:+-3.83 h-0.16 days <br />-0.0228 weeks <br />-0.00525 months <br />) | |
| Opened: | Ronald Fry 15:00 Dec 14, 2012 |
| NRC Officer: | John Knoke |
| Last Updated: | Dec 14, 2012 |
| 48595 - NRC Website | |
Unit 1 | |
|---|---|
| Reactor critical | Critical |
| Scram | No |
| Before | Power Operation (99 %) |
| After | Power Operation (99 %) |
Unit 2 | |
|---|---|
| Reactor critical | Critical |
| Scram | No |
| Before | Power Operation (99 %) |
| After | Power Operation (99 %) |