ENS 43722
ENS Event | |
|---|---|
06:20 Oct 13, 2007 | |
| Title | Technical Specification Required Shutdown Due to Inoperable Control Rods |
| Event Description | Susquehanna Unit 1 was being manually shutdown on 10/13/2007 for a planned maintenance outage to address control cell friction. Prior to the shutdown five control rods had been declared inoperable due to control cell friction. When reactor power was lowered to 10% at 0220, entry into Tech Spec 3.1.3 was required for 'One or more BPWS groups with four inoperable control rods'. The completion time for this specification is 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br />. The inoperability of the control rods condition cannot be cleared in the specified time. This condition results in the unit being in a 'Shutdown Required By Technical Specifications'. The required action is to be in Mode 3 within 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />. The Shutdown required by Technical Specifications is reportable as a 4 hour4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> Non-Emergency report under 10 CFR 50.72(b)(2)(i).
Manual insertion of control rods will continue until all rods are fully inserted. Hot Shutdown is expected by 0800, 10/13/07. Shutdown activities will continue to place the unit in cold shutdown. A Press Release will be made concerning the planned maintenance outage. The licensee notified the NRC Resident Inspector.
On October 13, 2007, Susquehanna operators began the process of shutting down Unit 1 for a planned maintenance outage to address known control cell friction issues. Because four of five control rods declared inoperable during the operating cycle were located in the same Banked Position Withdrawal Sequence (BPWS) group, station personnel realized that conditions for entry into Technical Specification (TS) 3.1.3 'Control Rod Operability' Condition E would already be met when thermal power reached 10% rated thermal power during the shutdown. (NOTE: TS 3.1.3 Condition E is not applicable when thermal power is > 10%). With power less than or equal to 10%, TS 3.1.3 Condition E mandates restoration of control rods to operable status within 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br />. If this 4 hour4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> completion time is not met, TS 3.1.3 Condition F mandates that the plant enter Mode 3 (Hot Shutdown) within the next 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />. At 0220 hours0.00255 days <br />0.0611 hours <br />3.637566e-4 weeks <br />8.371e-5 months <br /> on October 13, power was lowered to 10% power and TS 3.1.3 Condition E was entered. Control Room personnel, anticipating that the 4 hour4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> restoration window allowed by Condition E would expire before the LCO could be cleared, reported the shutdown as a shutdown required by Tech Specs per 10 CFR 50.72(b)(2)(i). The ENS report was made proactively before the 4 hour4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> restoration window had expired. Subsequently, the Unit 1 mode switch was placed to Shutdown (Mode 3) at 0610 hours0.00706 days <br />0.169 hours <br />0.00101 weeks <br />2.32105e-4 months <br /> on October 13. Because the timing of this mode change was within the 4 hour4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> restoration window provided by TS 3.1.3 Condition E and because TS 3.1.3 is no longer applicable once Mode 3 is attained, the Condition requiring shutdown (Condition F) was never entered as a result of the inoperable BPWS rods as was initially reported via EN #43722. However, TS 3.1.3 Condition F can also be directly entered if nine or more control rods become inoperable. As the controlled shutdown Progressed, four additional control rods had been conservatively declared inoperable because they failed to settle at latched position '00' in a reasonable period of time. (Note: LER reports 50-387/2005-002-00 and 50-387/2006-001-00 have previously discussed control rod friction experienced at Susquehanna.) Accordingly, TS 3.1.3 Condition F was entered at 0343 hours0.00397 days <br />0.0953 hours <br />5.671296e-4 weeks <br />1.305115e-4 months <br /> on October 13, 2007. This TS entry constitutes the initiation of a nuclear plant shutdown required by the plant's Technical Specifications and is thus reportable per 10CFR50.72(b)(2)(i). Sufficient compensatory measures had been enacted such that TS 3.1.3 Condition F was no longer applicable by the time the controlled plant shutdown was completed. Therefore, the 60-day reporting that is necessary when a nuclear plant shutdown is completed per a plant's Tech Specs does not apply. (Reference: 10 CFR 50.73(a)(2)(i)(A)) The licensee notified the NRC Resident Inspector. Notified the R1DO (Miller). |
| Where | |
|---|---|
Susquehanna  Pennsylvania (NRC Region 1) | |
| Reporting | |
| 10 CFR 50.72(b)(2)(i), Tech Spec Required Shutdown | |
| Time - Person (Reporting Time:+-1.08 h-0.045 days <br />-0.00643 weeks <br />-0.00148 months <br />) | |
| Opened: | Martin Lichtner 05:15 Oct 13, 2007 |
| NRC Officer: | Jason Kozal |
| Last Updated: | Nov 7, 2007 |
| 43722 - NRC Website | |
Unit 1 | |
|---|---|
| Reactor critical | Critical |
| Scram | No |
| Before | Power Operation (100 %) |
| After | Hot Shutdown (0 %) |
WEEKMONTHYEARENS 540782019-05-22T06:56:00022 May 2019 06:56:00
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