Presentation on theme: "Tracking and Trending of Steam Generator Leak Rate (SGLR) Monitor Backgrounds and Source Checks Anthony T Lonnett FENOC - BVPS Units 1 & 2 PO Box 4 ( Mail."— Presentation transcript:
Tracking and Trending of Steam Generator Leak Rate (SGLR) Monitor Backgrounds and Source Checks Anthony T Lonnett FENOC - BVPS Units 1 & 2 PO Box 4 ( Mail Stop A-BV-RAD ) Shippingport, PA Phone:
Is there an Alternate Title to this Presentation? Maybe…just ask yourself the following: Question: How easy is it to get a repeat AFI? Answer: Simple….just have more than one person assigned to implement a trending program.
Problem (INPO AFI CY.3-1) Performance of rad monitors used to identify pri-to-sec tube leakage is not adequately trended to promptly identify and evaluate loss of sensitivity between monitor calibrations This does not meet the guidance of Rec No. 3 to SOER 93-1, “Diagnosis and Mitigation of Reactor Coolant System Leakage Including Steam Generator Tube Ruptures”
Causes and Contributors - Part 1 A previous misconception that source checks could not be quantitative Ownership of the program was assigned to more than one individual Acceptance Criteria was not displayed on the plots (graphs) There was no continuity between the two areas that needed trended (see next page for details)
Causes and Contributors - Part 2 Monitor bkgds were plotted monthly, but source checks were plotted every 18 months. Neither of these were adequate Effect of bkgd subtract was not evaluated Data was plotted on a log scale rather than a linear scale. Data was plotted in terms of count rate rather than Percent Variance of the Acceptance Criteria.
Corrective Actions Related To: Obtaining Raw Data Ownership of the trending program was assigned to one individual Changed station Logs to (1) require weekly source checks, and (2) provide instructions on how to perform the source checks Initiated routine (weekly) trending of the background & source check data Added "background subtract value"
Corrective Actions Related To - Acceptance Criteria Developed the 1 st Acceptance Criteria to require the current background or source check data point to be within a 3- sigma band of the historical average
Corrective Actions Related To - Acceptance Criteria Developed the 2 nd Acceptance Criteria to require the current background or source check data point to be within +10% of the total average
Corrective Actions Related To - Acceptance Criteria Implemented electronic comparison to the two Acceptance Criteria described above Data outside the Acceptance Criteria must be documented in a Corrective Action to ensure an adequate investigation and resolution process is performed
Corrective Action Status In total, fourteen Corrective Actions were implemented to enhance the program for prompt detection of detector degradation All Corrective Actions have been implemented All SGLR program enhancements were implemented into a single station procedure
Evaluate Effectiveness of Corrective Actions The Corrective Actions implemented were evaluated using four separate methods
1st Method of Corrective Action Evaluation The 1 st method involved use of an internal Effectiveness Review Results: A total of 4 additional comments were generated. They were evaluated and Corrective Actions were implemented
2nd Method of Corrective Action Evaluation The 2 nd method involved an independent review from a Chemistry peer at INPO Results: A total of 4 comments were generated. They were evaluated and Corrective Actions were implemented
3rd Method of Corrective Action Evaluation The 3rd method involved an independent review from a Chemistry peer at another FENOC site Results: A total of 1 additional comment was generated. It was evaluated and Corrective Action was implemented
4th Method of Corrective Action Evaluation The 4 th method involved a final internal critical evaluation of background and source-check trends to determine if the revised SGLR monitoring program identifies appropriate failures Results: No additional comments generated
Results The revised trending program now provides meaningful results Results are reported to station management Since implementation of the revised program, there have been several instances where the program identified a degrading trend in detector performance
Unit 1 SGLR Monitor Backgrounds
Unit 1 SGLR Monitor Source Checks
Unit 2 SGLR Monitor Backgrounds
Unit 2 SGLR Monitor Source Checks
Conclusions The Corrective Actions implemented for trending SGLR radiation monitor backgrounds and source checks are effective to satisfy SOER 93-1 Summary: Weekly trending is considered “routine”. Monthly trending is a bad practice, and 18 month trending is a really bad practice.