ML11158A256
| ML11158A256 | |
| Person / Time | |
|---|---|
| Site: | Vogtle  |
| Issue date: | 06/15/2011 |
| From: | Patrick Boyle Plant Licensing Branch II |
| To: | Ajluni M Southern Nuclear Operating Co |
| Boyle P, DORL/LPL2-1, 415-3936 | |
| References | |
| TAC ME5778, TAC ME5779 | |
| Download: ML11158A256 (4) | |
Text
UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 June 15, 2011 Mr. M. J. Ajluni Nuclear Licensing Director Southern Nuclear Operating Company, Inc.
40 Inverness Center Parkway Post Office Box 1295, Bin - 038 Birmingham, AL 35201-1295
SUBJECT:
VOGTLE ELECTRIC GENERATING PLANT, UNITS 1 AND 2 - REQUEST FOR ADDITIONAL INFORMATION (RAI), STEAM GENERATOR (SG) WATER LEVEL HIGH-HIGH SETPOINT CHANGE TECHNICAL SPECIFICATION (TS) TABLE 3.3.2.1 TECHNICAL SPECIFICATIONS TASK FORCE-493-A (TAC ME5778 AND ME5779)
Dear Mr. Ajluni:
By letter dated March 3. 2011 (Agencywide Documents Access and Management System Accession No. ML110660458). Southern Nuclear Operating Company (SNC, the licensee),
submitted a license amendment request to change the TSs for Vogtle Electric Generating Plant (Vogtle), Units 1 and 2. The amendment would revise a nonconservative error discovered in the Engineered Safety Feature Permissive P-14, SG Water Level High-High instrument setpoint and associated allowable value. The proposed change will also resolve operability determination issues associated with potentially nonconservative TSs Allowable Values. This TS change incorporates the corrected nominal trip setpoint and allowable value in TS Table 3.3.2.1, "Engineered Safety Feature Actuation System Instrumentation," for Function 5c, SG Water Level High-High.
Responses to the enclosed RAI are needed for us to continue our review.
Please provide a response within thirty (30) calendar days of the date of this letter.
Sincerely, Patrick G. Boyle, Project Manager Plant Licensing Branch 11-1 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket Nos. 50-424 and 50-425
Enclosure:
RAI cc w/encl: Distribution via Listserv
REQUEST FOR ADDITIONAL INFORMATION LICENSE AMEMDMENT REQUEST TO REVISE STEAM GENERATOR (SG) WATER LEVEL HIGH-HIGH SETPOINT CHANGE - TECHNICAL SPECIFCATION (TS) TABLE 3.3.2.1 VOGTLE ELECTRIC GENERATING PLANT (VOGTLE), UNITS 1 AND 2 DOCKET NOS. 50-424 AND 50-425 TAC NOS. ME5778 AND ME5779 The Nuclear Regulatory Commission (NRC) staff has reviewed the information provided by Southern Nuclear Operating Company, Inc. (SNC, the licensee), for Vogtle Units 1 and 2, in its letter dated March 3, 2011 (Agencywide Documents Access and Management System (ADAMS) Accession Number ML110660458). However, the NRC staff has reviewed the licensee's submittal and determined that additional information is needed to complete the review, as follows:
- 1. On May 27, 2005, VogtJe reported that the setpoint for the P-14 function may not be accomplished in response to a feedwater malfunction event as described in Final Safety Analysis Report Section 15.1.2.1. The License Event Report (LER) 1-2005-002 (ADAMS Accession No. ML051530400) states that Westinghouse had determined that the SG Water high-high level setpoint be reduced from 86.0% to 83.1 %. However, the License Amendment Request (LAR) submitted by SNC states that the SG Water high-high level setpoints should be reduced from S87.9% to s82.5%. Please clarify why the values identified in the LAR are different than the values identified by Westinghouse in the LER.
- 2. Enclosure 6, Basic Westinghouse Uncertainty Methodology (pg 1), describes that the algorithm used to calculate the channel uncertainty was based on a Westinghouse paper (Reference 1 of Enclosure 6). However, this section notes that there are differences between the algorithm presented in the paper and the equation used for the calculations due to Vogtle specific characteristics.
a) Please describe the differences in the Vogtle design that require a modification to the algorithm to combine the uncertainty components for a channel.
b) Please describe how the uncertainty terms were combined in the equation and how these terms represent their contribution to total error. Also, please identify the terms considered to be random and independent, and which are random and dependent, and which are non-random, and provide the reasons why these terms are to be so classified.
- 3. The sample calculation for the SG Water high-high level setpoint, provided in Enclosure 6, does not provide sufficient information to make a determination that adequate margin has been established between the Analytical Limits and the Nominal Setpoints to allow for all instrument channel performance uncertainties.
a) Provide the source or data sheet for the values identified in Table 1 of Enclosure 6. This table only provides the individual component uncertainties.
Enclosure
-2 b) Provide data and/or analysis to show that the tolerance limits for this calculation have been based on a statistically sufficient quantity of sample data to bound these values and state the confidence level associated with the interval that contains 95 percent of the population of interest. Provide a basis for demonstrating why the confidence level used is appropriate.
c) The summary calculation should provide the basis for calculating the channel statistical allowance, analytical limit (AL), nominal trip setpoint (NTSP), field trip setpoint, allowable value (AV), as found tolerance, and as left tolerance. Demonstrate that with the instrument "as-found" value at the AV, under the worst-case condition the channel trip function will be achieved with a 95% probability before the AL is reached, with a 95%
confidence level.
- 4. Note 0) of Table 3.3.2-1 (page 5 of 7) in the TS markups provided in Enclosure 2 states "that the methodologies used to determine the as-found and the as-left tolerances are specified in NMP-ES-033-006, "Vogtle Setpoint Uncertainty Methodology and Scaling Instructions."
Further, Enclosure 4, Technical Specification Bases Markup Pages, state that "a detailed description of the methodology used to calculate the Allowable Values and NTSP is provided in the "RTS/ESFAS [Reactor Trip System/Engineered Safety Feature Actuation System] Setpoint Methodology Study" (WCAP-11269). Please provide copies (prefer electronic copy) of the following documents:
NMP-ES-033-006, "Vogtle Setpoint Uncertainty Methodology and Scaling Instructions. "
WCAP-11269, "RTS/ESFAS Setpoint Methodology Study" as supplemented by Amendments 34 and 14.
June 15,2011 Mr. M. J. Ajluni Nuclear Licensing Director Southern Nuclear Operating Company. Inc.
40 Inverness Center Parkway Post Office Box 1295, Bin - 038 Birmingham, AL 35201-1295
SUBJECT:
VOGTLE ELECTRIC GENERATING PLANT, UNITS 1 AND 2 - REQUEST FOR ADDITIONAL INFORMATION (RAI), STEAM GENERATOR (SG) WATER LEVEL HIGH-HIGH SETPOINT CHANGE TECHNICAL SPECIFICATION (TS) TABLE 3.3.2.1 TECHNICAL SPECIFICATIONS TASK FORCE-493-A (TAC ME5778 AND ME5779)
Dear Mr. Aj/uni:
By letter dated March 3, 2011 (Agencywide Documents Access and Management System Accession No. ML110660458), Southern Nuclear Operating Company (SNC, the licensee).
submitted a license amendment request to change the TSs for Vogtle Electric Generating Plant (Vogtle), Units 1 and 2. The amendment would revise a nonconservative error discovered in the Engineered Safety Feature Permissive P-14, SG Water Level High-High instrument setpoint and associated allowable value. The proposed change will also resolve operability determination issues associated with potentially nonconservative TSs Allowable Values. This TS change incorporates the corrected nominal trip setpoint and allowable value in TS Table 3.3.2.1, "Engineered Safety Feature Actuation System Instrumentation," for Function 5c, SG Water Level High-High.
Responses to the enclosed RAI are needed for us to continue our review.
Please provide a response within thirty (30) calendar days of the date of this letter.
Sincerely, IRA!
Patrick G. Boyle, Project Manager Plant Licensing Branch 11-1 Division of Operating Reactor licenSing Office of Nuclear Reactor Regulation Docket Nos. 50-424 and 50-425
Enclosure:
RAI cc w/encl: Distribution via Listserv DISTRIBUTION:
Public LPL2-1 RlF RidsNrrDorlLpl2-1 Resource RidsNrrDeEicb Resource RidsOgcRp Resource RidsAcrsAcnw MailCTR Resource RidsNrrLAMOBrien Resource RAlvarado. NRR RidsRgn2MailCenter Resource RidsNrrPMVogtle Resource ADAMS Accession No' ML11158A256 OFFICE NRRllPL2-1/PM NAME PBoyle DATE 6/8/11
- via memo dated 5/19/11 NRRllPl2-1/LA NRRlEICB/BC NRRlLPL2-1/BC NRRlLPL2-1/PM MOBrien GWilson*
GKulesa PBoyle 6/8/11 05119/11 6114111 6/15/11 OFFICIAL RECORD COpy