ML120760376
| ML120760376 | |
| Person / Time | |
|---|---|
| Site: | River Bend  |
| Issue date: | 03/16/2012 |
| From: | Wang A Plant Licensing Branch IV |
| To: | Burmeister B, Clark J, Williamson D Entergy Operations |
| Wang A, NRR/DORL/LPL4, 301-415-1445 | |
| References | |
| TAC ME7767 | |
| Download: ML120760376 (2) | |
Text
From:
Wang, Alan Sent:
Friday, March 16, 2012 1:27 PM To:
'BURMEISTER, BARRY M'; 'Joseph Clark (JCLARK@entergy.com)';
WILLIAMSON, DANNY H Cc:
Burkhardt, Janet; Lent, Susan
Subject:
River Bend Station, Unit 1 (RBS) Request for Additional Information Regarding Degraded Voltage Surveillance Frequency Extension TS Change (ME7767)
Barry, Danny and Joey, By letter dated December 8, 2011 (Agencywide Documents Access and Management System (ADAMS) Accession Nos. ML11349A246), Entergy Operations, Inc (Entergy, the licensee) submitted Entergy Letter RBG-47193, License Amendment Request 2011-05 Degraded Voltage Surveillance Frequency Extension and Allowable Value Changes. In this letter, Entergy submitted a request to extend the frequency of Surveillance Requirement (SR) 3.3.8.1.3 (calibration of loss of power instrumentation) from 18 to 24 months and revise certain allowable values in TS 3.3.8.1, Loss of Power Instrumentation.
The NRC staff has determined that the following additional information is needed to complete our review. This request was discussed with Mr. Danny Williamson of your staff on March 15, 2012, and it was agreed that a response would be provided by April 20, 2012. If circumstances result in the need to revise the requested response date, please contact me at (301) 415-1445 or via e-mail at Alan.Wang@nrc.gov..
The LAR requests amendment of the TS to (1) extend the frequency of Surveillance Requirement (SR) 3.3.8.1.3 for calibration of Loss of Power instrumentation from 18 to 24 months, and (2) revise the following Allowable Values (AV) in TS 3.3.8.1, Loss of Power Instrumentation. The following questions pertain to the proposed changes:
In Section 3.1 of Attachment 1 to the LAR dated December 8, 2011:
For each component having a surveillance interval extended, historical surveillance test data and associated maintenance records were reviewed in evaluating the effect on safety. In addition, the licensing basis was reviewed for functions associated with each revision to ensure it was not invalidated. Based on the results of these reviews, it is concluded that there is no adverse effect on plant safety due to increasing the surveillance test intervals from 18 to 24 months with the continued application of SR 3.0.2, which allows a 25% extension (i.e., grace period up to 30 months) to SR frequencies.
RBS setpoint calculations, and affected calibration and functional test procedures, have been revised, or will be revised prior to implementation to reflect the new 30-month drift values. The revised setpoint calculations were developed in accordance with the RBS commitment to the guidance provided in Regulatory Guide 1.105, "Instrument Setpoints" (Reference 3 of your December 8, 2012, letter) as implemented by the RBS setpoint methodology (Reference 5 of your December 8, 2012, letter).
For each of the functions in TS 3.3.8.1 for which the Allowable Value (AV) is being modified provide:
- a. The results of the drift analysis performed indicating the total periods for which the drift data was collected, the magnitude of drifts observed, the drifts permitted by the existing setpoint calculations, the outliers rejected in the drift evaluation with the explanation for rejecting them, and the normality tests performed. Also include justifications for the methodology used to calculate the projected drift values corresponding to 30 months interval (based on application of the 25% extension) from drift values available from the surveillance tests.
- b. Details of the setpoint calculation methodology used with representative setpoint calculations to establish the analytical limit, total loop uncertainties, the nominal trip set point, as-found tolerance, and as-left tolerance. Especially, if a correction factor of 1.645/2 is used in calculating the loop uncertainty, provide justification of this correction factor for the proposed TS AVs.
- c. Documentation to demonstrate that the drifts values for all the devices used in the setpoint calculations are valid for a minimum of 95/95 confidence level proposed in RG 1.105., i.e. - 2 to 2.
- d. Describe the measures to be taken to ensure that the associated instrument channels are capable of performing their specified safety functions in accordance with applicable design requirements and associated safety analysis used in clauses 3.a and 3.b. Include in your discussion:
A. Information on the controls you employ to ensure that the as-left trip settings after completion of periodic surveillances are consistent with your setpoint calculation methodology.
B. The plant corrective action processes (including plant procedures) for restoring channels to operable status when channels are found to be outside the acceptable as-found values and when they are found to be outside AVs, especially, when they cannot be reset within the acceptable as-left values.
Alan Wang Project Manager (River Bend Station)
Nuclear Regulatory Commission Division of Operating Reactor Licensing