05000446/LER-2008-002
| Document Number05 22 2008 2008 L002 00 07 14 2008 N/A 05000 | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications 10 CFR 50.73(a)(2)(v), Loss of Safety Function |
| 4462008002R00 - NRC Website | |
I. DESCRIPTION OF THE REPORTABLE EVENT
A. REPORTABLE EVENT CLASSIFICATION
10CFR50.73(a)(2)(i)(B); "Any operation or condition which was prohibited by the plant's Technical Specifications.
B. PLANT OPERATING CONDITIONS PRIOR TO THE EVENT
On May 22, 2008, CPNPP Unit 2 was in Mode 1, operating at 100% power.
C. STATUS OF STRUCTURES, SYSTEMS, OR COMPONENTS THAT WERE INOPERABLE AT THE START OF
THE EVENT AND THAT CONTRIBUTED TO THE EVENT
There were no structures, systems, or components that were inoperable at the start of the event that contributed to the event.
D. NARRATIVE SUMMARY OF THE EVENT, INCLUDING DATES AND APPROXIMATE TIMES
On May 14, 2008, CPNPP Unit 2 was in Mode 1 operating at 100% power. At 1315 hours0.0152 days <br />0.365 hours <br />0.00217 weeks <br />5.003575e-4 months <br />, a Reactor Operator (R0#1) (utility, licensed) began a Channel Operational Test (COT) and Channel Calibration on channel 2-L-0552 (SG 2-02 Protection Set II Narrow Range Level Channel) [EIIS: (SB)(SG)(CHA)]. This test is performed per Technical Specification (TS) Surveillance Requirement (SR) 3.3.2.5 and it verifies the accuracy of the channel sensor and associated signal processing equipment contained in the channel. Per step 6.5 of the test procedure, RO#1 positioned hand switch 2-LS-0529C (RCS SG Liquid Level Hand Switch for Loop 2, Protection Set I) [EIIS:
(SB)(SG)(CHA)(HS)] to the 2-LY-0529 position (the alternate channel position). This renders P-14 (high-high level trip function) inoperable for channel 2-L-0529 (SG 2-02 Protection Set I Narrow Range Level Channel), requiring entry into TS Limiting Condition for Operation (LCO) 3.3.2 condition I, which has a 72 hour8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> completion time to place the channel in trip or place the Unit in Mode 3 within 78 hours9.027778e-4 days <br />0.0217 hours <br />1.289683e-4 weeks <br />2.9679e-5 months <br />.
Step 9.17 of the COT procedure states "Notify the RO that the following hand switch may be positioned as required by plant conditions (Operations Sign Off): 2-LS-0529C "SG2 LVL CHAN SELECT." The restoration step was worded this way to allow flexibility for various plant conditions. An I&C technician (utility, non-licensed) notified a second Reactor Operator (R0#2) (utility, licensed) as directed by step 9.17 of the COT procedure.
Procedure step 9.17 does not require concurrent verification, and the I&C Technician is not required to ensure the hand switch is returned to the preferred channel. RO#2 was unaware of the TS 72 hour8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> completion time to place the channel in trip or place the Unit in Mode 3 within 78 hours9.027778e-4 days <br />0.0217 hours <br />1.289683e-4 weeks <br />2.9679e-5 months <br /> with hand switch 2-LS-0529C in the 2-LY-0529 position. Since the COT procedure did not specifically direct hand switch 2-LS-0529C to be repositioned to the 2 L-0552 position (the normal controlling channel), RO#2 left 2-LS-0529C in the 2-LY-0529 position (the alternate channel position).
The Unit Supervisor (utility, licensed) performed the surveillance review for channel 2-L-0552 and believed that all actions had been completed to restore channels 2-L-0552 and 2-L-0529 to Operable status. At 1404, the channels were determined to be Operable and the Unit Supervisor exited the LCO. Between May 14 and May 22, 2008, Reactor Operators (utility, licensed) performed routine Main Control Board (MCB) walk downs. Since no annunciators or plant computer data are associated with the alternate channel selected, it was not readily apparent to the Reactor Operators performing the MCB walk downs that the alternate channel was controlling SG 2-02 level.
On May 22, 2008 at 1120 hours0.013 days <br />0.311 hours <br />0.00185 weeks <br />4.2616e-4 months <br />, during a routine MCB walk down, a Reactor Operator (R0#3) (utility, licensed) noticed that hand switch 2-LS-0529C was in the incorrect position. At 1137 hours0.0132 days <br />0.316 hours <br />0.00188 weeks <br />4.326285e-4 months <br />, hand switch 2 LS-0529C was positioned to the normal controlling channel 2-L-0552.
Since P-14 for 2-L-0529 was inoperable for 8 days while hand switch 2-LS-0529C was in the incorrect position, and this exceeded the required completion time for placing the channel in trip within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> or being in Mode 3 within 78 hours9.027778e-4 days <br />0.0217 hours <br />1.289683e-4 weeks <br />2.9679e-5 months <br /> per LCO 3.3.2 Condition I, this condition is reportable per 10CFR50.73(a)(2)(i)(B); "Any operation or condition which was prohibited by the plant's Technical Specifications.
E. THE METHOD OF DISCOVERY OF EACH COMPONENT OR SYSTEM FAILURE, OR PROCEDURAL OR
PERSONNEL ERROR
During a routine MCB walk down, a Reactor Operator (utility, licensed) noticed that hand switch 2-LS-0529C was in the incorrect position.
II. COMPONENT OR SYSTEM FAILURES
A. FAILURE MODE, MECHANISM, AND EFFECT OF EACH FAILED COMPONENT
Not applicable — there were no component failures associated with this event.
B. CAUSE OF EACH COMPONENT OR SYSTEM FAILURE
Not applicable - there were no component failures associated with this event.
C. SYSTEMS OR SECONDARY FUNCTIONS THAT WERE AFFECTED BY FAILURE OF COMPONENTS WITH
MULTIPLE FUNCTIONS
Not applicable - there were no component failures associated with this event.
D. FAILED COMPONENT INFORMATION
Not applicable - there were no component failures associated with this event.
III. ANALYSIS OF THE EVENT
A. SAFETY SYSTEM RESPONSES THAT OCCURRED
Not applicable — no safety system responses occurred during this event.
B. DURATION OF SAFETY SYSTEM TRAIN INOPERABILITY
As discussed above, P-14 for 2-L-0529 was inoperable for 8 days while hand switch 2-LS-0529C was in the incorrect position.
C. SAFETY CONSEQUENCES AND IMPLICATIONS OF THE EVENT
During the time frame that hand switch 2-LS-0529C was in the 2-LY-0529 position, the Unit 2 SG 2-02 high-high level P-14 trip function was inoperable per TS. The P-14 signal provides the following functions when a high-high water level occurs in the SG: 1) trips the Main Feedwater Pumps, 2) trips the Main Turbine, and 3) generates a Feedwater isolation signal. Steam generator narrow range water level channel 2-L-0552 is required to be the controlling channel to preserve the control system/protection system isolation which affects the required protection logic in the presence of an assumed single active failure. With 2-L-0552 as the controlling channel, the P-14 level protection may be derived from a two of three coincident logic from channels 2-L-0527 (SG 2-02 Protection Set IV Narrow Range Level Channel), 2-L-0528 (SG 2-02 Protection Set III Narrow Range Level Channel) and 2-L-0529 (SG 2-02 Protection Set I Narrow Range Level Channel).
During the time frame that 2-LS-0529C was in the 2-LY-0529 position (from May 14 to May 22, 2008) channels 2 L-0527 and 2-L-0528 remained Operable. Even though channel 2-L-0529 was technically inoperable per TS 3.3.2 Condition I, it would still have been able to perform its trip function. During this event, a SG 2-02 high-high level condition did not occur on Unit 2. Since a failure of 2-L-0529 did not occur from May 14 to May 22, 2008, the P-14 signal would have been generated as required if a SG 2-02 high-high level condition had occurred during this time period.
Based on the above, it is concluded that the health and safety of the public were unaffected by this condition and this event has been evaluated to not meet the definition of a safety system functional failure per 10CFR50.73(a)(2)(v).
IV. CAUSE OF THE EVENT
The cause of this event was a RCS SG Liquid Level Hand Switch for Loop 2, Protection Set I being left in the incorrect position due to a less than adequate restoration step in a Channel Operational Test procedure. To allow flexibility for various plant conditions, the restoration step was vague and did not specifically direct the Reactor Operator to restore the switch to a position that would maintain compliance with the completion times in the TS.
V. CORRECTIVE ACTIONS
Immediate corrective actions included issuing a Shift Order to add switch restoration to the LCOAR termination requirements and to require use of Plant Status Control Aids whenever a MCB switch is out of its normal alignment.
As a part of the CPNPP Corrective Action Program, all l&C procedures that involve manipulation of the SG level control switches will be revised to provide specific restoration steps, labeling on the SG level control hand switches will be enhanced, and the Operations training material associated with the SG water level alternate channel will be reviewed to ensure that it adequately addresses TS implications.
VI. PREVIOUS SIMILAR EVENTS
There have been no previous similar reportable events at CPNPP in the last three years.
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