ML110680373
| ML110680373 | |
| Person / Time | |
|---|---|
| Site: | Saint Lucie  |
| Issue date: | 03/09/2011 |
| From: | Orf T Plant Licensing Branch II |
| To: | Wasik C Florida Power & Light Co |
| Orf, T J, NRR/DORL/301-415-2788 | |
| References | |
| Download: ML110680373 (3) | |
Text
From:
Orf, Tracy Sent:
Wednesday, March 09, 2011 1:27 PM To:
'Wasik, Chris'
Subject:
St. Lucie Unit 1 EPU - request for additional information (I & C)
Dear Mr. Wasik,
By letter dated November 22, 2010 (Agencywide Documents Access and Management System Accession No. ML103560415) Florida Power & Light Company (the licensee) submitted a license amendment request for St. Lucie Unit 1.
The U.S. Nuclear Regulatory Commission (NRC) staff has reviewed the licensee's submittal and has concluded that additional information is required from the licensee in order for the NRC staff to complete their review. The questions below describe these requests for additional information (RAls).
The NRC requests that the licensee respond to these RAls within 30 days of the date of this e-mail. If the licensee concludes that more than 30 days are required to respond to the RAls, the licensee should request additional time, including a basis for why the extension is needed.
Please contact me at the number below or by e-mail if you have any questions on this issue or if you require additional time to submit your responses.
Sincerely, Tracy J. Orf, Project Manager St. Lucie Plant Licensing Branch II-2 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Phone: (301) 415-2788 EICB-4.
The notes for the setpoints (Notes 1 and 2) are not consistent with the notes contained in the guidance provided in the April 30, 2010 for TSTF-493 (ML093570168 and ML100710442). Note 1 in Attachment 3 (page 2-4) of the licensing amendment request (LAR), reference ML1003560419, states that If the as-found channel setpoint is either outside its predefined as-found acceptance criteria band or is not conservative with respect to the Allowable Value, then the channel shall be declared inoperable and shall be evaluated to verify that it is functioning as required before returning the channel to service. Further, in, Appendix E (page E-4) of the LAR it is explained that for St. Lucie the operability limit (OL) is synonymous with the as found acceptance criteria band. However, from the values presented in Attachment 5, Appendix E, page E-4, it appears that the OL are not symmetrical around the field trip setpoint (FTSP) of 35.5%, i.e. OL+ is 36.68% and OL-is 34.78%. Thus OL+ is 1.18% off from FTSP, whereas OL-is off by only 0.72% from the FTSP. If OL is synonymous with as-found tolerance (AFT) then it should be 2xST (setting tolerance) or 0.5% in accordance with Attachment 5, Appendix E, page E-4.
Thus, the OL band is greater than the calculated AFT of 0.5%. Since the FTSP
is more conservative as compared with the calculated trip setpoint, an as-found value greater than the calculated AFT indicates that the instrument may not be functioning within the design values even if it is acceptable from the point of view of operability.
Hence, the first note requires evaluation of the channel performance whenever the as-found value for the channel setpoint is found outside its AFT but conservative with respect to allowable value (AV). TSTF-493 further clarifies that AFT is to be applied about the limiting trip setpoint (LTSP) or about any other more conservative setpoint. Evaluation of the channel performance will verify that the channel will continue to perform in accordance with safety analysis assumptions and the channel performance assumption in the setpoint methodology. The purpose of the assessment is to ensure confidence in the channel performance prior to returning the channel to service. When the as-found deviation is found to exceed the AFT, an evaluation shall be made in accordance with the plant corrective action procedures (CAP) to verify that the instrument is functioning as designed. The licensee is requested to clarify how Note 1 meets the guidance of RIS 2006-17 and TSTF-493 from the instrument design point of view when the as-found value is found to be greater than AFT.
The licensee should further clarify what action/s will be taken when the as-found value is found to be greater than AFT. In addition, licensee is requested to justify the statement that OL and AFT are synonymous from the instrument design point of view as explained in RIS 2006-17.
EICB-5.
Similarly St. Lucie note 2 states that The instrument channel setpoint shall be reset to a value that is within the as-left tolerance of the Trip Setpoint, or a value that is more conservative than the Trip Setpoint, otherwise that channel shall not be returned to Operable status. The Trip Setpoint and the methodology used to determine the Trip Setpoint, the as-found acceptance criteria band, and the as-left acceptance criteria are specified in the UFSAR. This note is also not consistent with the guidance contained in TSTF-493. The standard note in TSTF-493 further states that Setpoints more conservative than the LTSP are acceptable provided that the as-found and as-left tolerances apply to the actual setpoint implemented in the surveillance procedures (Nominal Trip Setpoint).
The nominal trip setpoint (NTSP) is the same as the FTSP in case of St. Lucie Unit 1. If the instrument cannot be reset to a value which is within the as-left tolerance (ALT) of the FTSP then it must be evaluated for proper operation and the evaluation recorded in the plant CAP. The licensee is requested to explain how Note 2 meets the guidance of RIS 2006-17 and TSTF-493 and what evaluation/s will be performed when the as-left value is found to exceed the ALT.
In addition, please provide a description of the criteria that triggers an entry into the corrective action program and the criteria for declaring the instrument as inoperable.
EICB-6.
The summary of the calculation provided does not contain all the information needed by Staff to complete the review. The licensee is requested to provide the Staff with a copy of the calculation since this is the only calculation that involves setpoint change. The calculation should clearly state the as-found tolerance, as-left tolerance, the allowable value and the NTSP or the FTSP.
EICB-7.
Combining errors under the square root of sum of squares (SRSS) is based on the assumptions that all such errors are random in nature. The information docketed with the licensing amendments request does not justify the rationale for combining the errors under the SRSS. Please describe the nature of the errors and justify using the SRSS for combining these errors.
EICB-8.
In the second paragraph of item II on page E-3 of Attachment 5, Appendix E there is an equation that notes that (TLU + ST SAPP UA). This equation is missing the sign after TLU + ST. Please clarify the equation.