05000387/LER-2006-001, Re TS Required Shutdown Due to Excessive Control Cell Friction
| ML061240380 | |
| Person / Time | |
|---|---|
| Site: | Susquehanna  |
| Issue date: | 04/25/2006 |
| From: | Saccone R Susquehanna |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| PLA-6047 LER 6-001-00, LER-06-001-00 | |
| Download: ML061240380 (5) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(i)(A), Completion of TS Shutdown 10 CFR 50.73(a)(2)(i) 10 CFR 50.73(a)(2)(ii)(A), Seriously Degraded 10 CFR 50.73(a)(2)(ii)(B), Unanalyzed Condition 10 CFR 50.73(a)(2)(iii) 10 CFR 50.73(a)(2)(iv)(A), System Actuation 10 CFR 50.73(a)(2)(x) 10 CFR 50.73(a)(2)(v)(A), Loss of Safety Function - Shutdown the Reactor 10 CFR 50.73(a)(2)(v)(B), Loss of Safety Function - Remove Residual Heat 10 CFR 50.73(a)(2)(v), Loss of Safety Function 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications |
| 3872006001R00 - NRC Website | |
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R A.Saccone Vice President - Nuclear Operations PPL Susquehanna, LLC 769 Salem Boulevard Berwick, PA 18603 Tel. 570.542.3959 Fax 570.542-1504 rasaccone@pplweb.com PP APR 2 5 2006 U. S. Nuclear Regulatory Commission Attn: Document Control Desk Mail station OP1-17 Washington, DC 20555 SUSQUEHANNA STEAM ELECTRIC STATION LICENSEE EVENT REPORT 50-387/2006-001-00 PLA-6i047 Docket 50-387 Attached is Licensee Event Report 50-387/2006-001-00. On March 3, 2006, Susquehanna operators began the process of shutting down Unit I for its 14th Refueling and Inspection Outage. As control rods were inserted during the course of the controlled shutdown, those that remained at the full-in position instead of settling and latching at the 00 position within a reasonable period of time were conservatively declared inoperable per Technical Specification 3.1.3, "Control Rod Operability". This Technical Specification, which requires shutdown when nine or more rods are declared inoperable, was entered at 0517 hours0.00598 days <br />0.144 hours <br />8.54828e-4 weeks <br />1.967185e-4 months <br /> on March 4, 2006.
This event was determined to be reportable per 10 CFR 50.73(a)(2)(i)(A) because Susquehanna Unit 1 was shut down as required by Technical Specification action statements.
There were no actual consequences to the health and safety of the public as a result of this event.
No new regulatory commitments have been created through issuance of this report.
RoberA. Saccone Vice President - Nuclear Operations Attachment C -leD-'a Document Control Desk PLA-6047 cc:
Mr. S. J. Collins Regional Administrator U. S. Nuclear Regulatory Commission 475 Allendale Road
'King of Prussia, PA 19408
- vIr. A. J. Blamey Sr. Resident Inspector U. S. Nuclear Regulatory Commission P.O. Box 35
- Berwick, PA 18603-0035 her. R. Osborne Allegheny Electric Cooperative p. 0. Box 1266 Harrisburg, PA 17108-1266 Mr. R. R. Janati Bureau of Radiation Protection Rachel Carson State Office Building
]'. 0. Box 8469 Harrisburg, PA 17105-8469
NRC FORM 366 U.S NUCLEAR REGULATORY APPROVED BY OMB: NO. 3150-0104 EXPIRES: 06/30/2007 6-2004) the NRC may not conduct or sponsor, and a person is not required to respond to, digits/characters for each block) the information collection.
- 1. FACILITY NAME Susquehanna Steam Electric Station - Unit 1
. DOCKET NUMBER
- 3. PAGE 05000387 1 0F3
- 4. TITLE TS Required Shutdown Due to Excessive Control Cell Friction
- 5. EVENT DATE
- 6. LER NUMBER
- 7. REPORT DATE
- 8. OTHER FACILIES INVOLVED Y
YEAR YEAR SEQUENTIAL REV M
DAY YEAR FACILITY NAME POCKET NUMBER MNH DY YA YERINUMBER I NO.
MOT DAY YER 5000 FACILITY NAME DOCKET NUMBER 3
2006 2006 001 00 4
25 2006 05000
- 9. OPERATING MODE 11.THIS REPORTIS SUBMIMtED PURSUANTTOTHE REQUIREMENTS OF 10 CFR§: (Check all that apply)
El 20.2201(b)
[El 20.2203(a)(3)(i)
El 50.73(a)(2)(i)(C)
El 50.73ia)(2)(vii)
- 10. POWER LEVE:L 20.2201(d)
El 20.2203(a)(3)(ii)
El 50.73(a)(2)(ii)(A)
E 50.73ia)(2)(viii)(A) lo 20.2203(a)(1)
El 20.2203(a)(4)
El 50.73(a)(2)(ii)(B)
El 50.731a)(2)(viii)(B) 0%
El 20.2203(a)(2)(i)
El 50.36(c)(1)(i)(A)
[1 50.73(a)(2)(iii)
[I 50.73ja)(2)(ix)(A)
El 20.2203(a)(2)(ii)
El 50.36(c)(1)(ii)(A) l 50.73(a)(2)(iv)(A)
El 50.73(a)(2)(x)
El 20.2203(a)(2)(iii)
El 50.36(c)(2)
El 50.73(a)(2)(v)(A)
Dl 73.71 (a)(4) 0l 20.2203(a)(2)(iv)
El 50.46(a)(3)(ii)
El 50.73(a)(2)(v)(B)
[I 73.71 (a)(5) o 20.2203(a)(2)(v) 0 50.73(a)(2)(i)(A)
El 50.73(a)(2)(v)(C)
El OTHER El 20.2203(a)(2)(vi)
El 50.73(a)(2)(i)(B)
El 50.73(a)(2)(v)(D)
Specify in Abstract below or in (if more space is required, use additional copies of NRC Form 366A)
EVENT DESCRIPTION
On March 3, 2006, Susquehanna operators (Licensed, Utility) began the process of shutting down Unit 1 fo' its 14 th Refueling and Inspection Outage. As had previously been experienced during Unit 1's last shutdown in October 2005, the station anticipated that known control cell (EIIS Code: AC) friction issues would result in the slow settling of some control rods (EIIS Code: JD) as they were inserted to the full in position. The cell friction issues manifested during Unit 1's 14th fuel cycle when multiple control rods failed to settle into their targeted latched position within 30 seconds. Although previous experience suggested that operability could be demonstrated for a majority of slow settling control rods, it was conservatively determined that those rods which failed to settle in a reasonable period of time during the shutdown would be declared inoperable. Technical Specification (TS) 3.1.3, Control Rod Operability, would be entered when nine rods had been declared inoperable.
As anticipatec, TS 3.1.3.f was entered at 0517 hours0.00598 days <br />0.144 hours <br />8.54828e-4 weeks <br />1.967185e-4 months <br /> on March 4, 2006 when the ninth control rod was declared inoperable. Entry into TS 3.1.3.f requires that the Unit be taken to Mode 3, Hot Shutdown, within 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />. At the time the ninth control rod was declared inoperable, Unit 1 had already been reduced to approximately 0% power. The controlled shutdown continued until 0743 hours0.0086 days <br />0.206 hours <br />0.00123 weeks <br />2.827115e-4 months <br /> when insertion of all rods was completed and Mode 3 had been entered by placing the mode switch to the Shutdown position.
There were no Emergency Core Cooling System (EIIS Code: B) initiations and no challenges to containment (EIIS Code: NH) experienced during the shutdown.
Even though the plant shutdown was planned and in-progress, the shutdown became a Technical Specification mandate at 0517 hours0.00598 days <br />0.144 hours <br />8.54828e-4 weeks <br />1.967185e-4 months <br /> on March 4 when the ninth control rod was declared inoperable. Accordingly, this event is being reported as a Tech Spec required shutdown per 10 CFR 50.73(a)(2)(i)(A).
CAUSE OF EVENT
Entry into the shutdown TS was the result of a station strategy that emphasized a controlled Unit shutdown. This strategy recognized the need to enter TS 3.1.3.f. Entry into the Limiting Condition of Operation (LCO) did not impact the course of the shutdown in any way. Entry into TS 3.1.3.f was readily avoidable via manual RPS (EIIS Code: JC) initiation before LCO control rod operability limits were threatened. Such action would have, however, entailed the unnecessary implementation of the scram safety function to complete a normal, planned shutdown and would have precluded the operational advantages inherent with a controlled Unit shutdown.
ANALYSIS / SAFETY SIGNIFICANCE There was no significance to the administrative entry to TS 3.1.3.f. The control rod drive system (EIIS Code: AA) remained fully capable of performing its function throughout the shutdown. The control rods that were declared inoperable had been fully inserted. Associated control rod drives were hydraulically isolated to prevent rod wNithdrawal.
Being fully inserted, the control rods were fulfilling their design function. As such, there were no adverse safety consequences resulting from this event.1-2001)
U.S. NUCLEAR REGULATORY COMMISSION LICENSEE EVENT REPORT (LER)
- 1. FACILITY NAME
- 4 PAGE Susquehanna Steam Electric Station - Unit 1 3OF3
- 17. NARRA7iVE (If more space is required, use additonal copies o CORRECTIVE. ACTIONS None required. Entry into the shutdown Technical Specification was the result of a non-impacting shutdown decision strategy.
ADDITIONAL INFORMATION
Channel bow is contributing to the cell friction issues being experienced at Susquehanna. All control cells exhibiting slow to settle control rods were evaluated. Associated fuel assemblies were measured for channel bow if they would remain in a control cell during the upcoming operating cycle. Those fuel assemblies causing interference have either been removed from the core, re-channeled (3 tV is outage), or moved to a peripheral location in the core where control blade interference is not possible. The cell friction issue continues to be managed in Susquehanna's corrective action program.
Past Similar Events:
Docket No. 50-387 LER 2005-002-00