ML060860223
| ML060860223 | |
| Person / Time | |
|---|---|
| Site: | Sequoyah  |
| Issue date: | 03/16/2006 |
| From: | Pace P Tennessee Valley Authority |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| TAC MC8246, TAC MC8247, TVA-SQN-TS-05-04 | |
| Download: ML060860223 (7) | |
Text
1 ennessee Valley Authority, Post Office Box 2000, Soddy-Daisy, Tennessee 37384-2000 March 16, 2006 TVA-SQN-TS-05-04 10 CFR 50.90 U.S. Nuclear Regulatory Commission ATTN:
Document Control Desk Washington, D. C. 20555-0001 Gentlemen:
- En the Matter of Tennessee Valley Authority
)
Docket Nos. 50-327 50-328
- 3EQUOYAH NUCLEAR PLANT (SQN)
UNITS 1 AND 2 -
TECHNICAL SPECIFICATIONS (TS) CHANGE 05-04, RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION (RAI)
(TAC NOS.
References:
- 1. NRC letter to TVA dated January 27, 2006, "Sequoyah Nuclear Plant, Units 1 and 2 -
Request for Additional Information Regarding Revision of Allowable Value for Reactor Trip System -
Turbine Trip on Low Trip System Pressure (TAC Nos. MC8246 and MC8247)"
Units 1 and 2 Technical Specification (TS) Change 05-04, Revision of Allowable Value for Reactor Trip System-Turbine Trip on Low Trip System Pressure" this letter responds to the request for additional information in Reference 1 associated with the TS change request in Reference 2. The enclosure provides TVA's responses to NRC's request.
There are no commitments contained in this letter.
-r-,?)C)
LLIN-)
PN ted on mecyled Pgew
U.S. Nuclear Regulatory Commission Page 2 March 16, 2006 If you have any questions about this change, please contact me at 843-7170 or Jim Smith at 843-6672.
I declare under penalty of perjury that the foregoing is true and correct.
Executed on this 16th day of March, 2006.
Sincerely, P. L. Pace Manager, Site Licensing and Industry Affairs
Enclosure:
Response to Request for Additional Information cc:
See page 3
U.S. Nuclear Regulatory Commission Page 3 March 16, 2006 Enclosure cc (Enclosure):
Framatome ANP, Inc.
P. 0. Box 10935 Lynchburg, Virginia 24506-0935 ATTN:
Mr. Frank Masseth Mr. Donald L. Gillispie Grace Glens Farm 3440 Union Church Road Thaxton, Virginia 24174 Mr. Edgar D. Hux 94 Ridgetree Lane Marietta, Georgia 30068 Mr. Lawrence E. Nanney, Director Division of Radiological Health Third Floor L&C Annex 401 Church Street Nashville, Tennessee 37243-1532 Mr. Douglas V. Pickett, Senior Project Manager U.S. Nuclear Regulatory Commission Mail Stop 08G-9a One White Flint North 11555 Rockville Pike Rockville, Maryland 20852-2739 Mr. William T. Russell 400 Plantation Lane Stevensville, Maryland 21666
en;14 ENCLOSURE TENNESSEE VALLEY AUTHORITY (TVA)
SEQUOYAH NUCLEAR PLANT (SQN)
UNITS 1 AND 2 NRC Requested Information:
The license amendment request (LAR) proposes a technical specification (TS) change to revise the reactor protection system turbine trip allowable value for low trip system pressure from greater than or equal to 43 pounds per square inch gauge (psig) to 39.5 psig. This change affects Functional Unit 17.A of TS 2.2.1, "Reactor Trip System Instrumentation Setpoint," in TS Table 2.2-1.
To assess the acceptability of the LAR related to setpoint changes, please provide the following information:
- 1.
'Setpoint Calculation Methodology: Provide documentation (including sample calculations) of the methodology used fcr Establishing the limiting nominal setpoint and the limiting acceptable values for the As-Found and As-Left setpoints as measured in periodic surveillance testing as described
.12elow. Indicate the related Analytical Limits and other limiting design values (and the sources of these values) for each setpoint."
Response
Although the following Allowable Value determination does not involve an Analytical Limit (non Safety Limit-Related),
tI-he methodology used complies with the intent of Method 1 defined within Section 7.3 of ISA-RP67.04.02.
The allowance between the Allowable Value and the trip setpoint only accounts for drift, calibration uncertainties for the channel tested, and instrument uncertainties during normal operation that are measured during testing.
TVA Calculation IDQ00004720050001 RO has been prepared to define an Allowable Value for the switch setpoint of 45 psig.
The accuracy terms for switch Repeatability (Re),
Drift (De), and Temperature Effects (TNe) defined within the calculation are based on data supplied by the switch nanufacturer.
These terms are summarized as follows:
Re = +/- 2.0 psig De = +/- 2.0 psig TNe = +/- 3.2 psig Whereas, the switch setpoint As-left Calibration Tolerance (Ab), Input Calibration Test Equipment Accuracy (ICTe) and Reading Error (ICRe) allowances are:
Ab = +/- 2.0 psig E-1
J.
ICTe = +/- 2.0 psig ICRe = +/- 2.0 psig As noted above, the switch Setpoint As-Left Calibration
.Tolerance (Ab) has been conservatively defined as equal to the switch Repeatability (Re) value of 45 +/- 2.0 psig.
Per TVA methodology, the minimum allowable value for this switch function is based on the following equation:
.llowable Value'= Setpoint -
Normal Measurable Accuracy (Anf)
The Setpoint is defined as 45 psig and Anf is defined with the following equation:
A =
Re2 +De2 +TNe2 +ICTe2 +ICRe 2 +Ab 2 Anf
= +/-+2.02 +2.02+3.2+2.02 +2.02 +2.02 psig Anf = + 5.5 psig Based on the above calculation, the Acceptable As-Found value for the setpoint is defined as 45 +/- 5.5 psig and the Setpoint Allowable Value is defined as follows:
Allowable Value = Setpoint -
Normal Measurable Accuracy (Anf)
Allowable Value = 45 psig -
5.5 psig Allowable Value = 39.5 psig Utilizing Westinghouse Electric Company Methodology, the Allowable Value is based upon the following equation that involves the determination of a conservative "trigger value," the difference between the trip setpoint and the Allowable Value.
Allowable Value = Setpoint -
the lowest (most restrictive) of the "trigger values" of T1 or T2 Determination of T1 and T2:
T, =RCA + RMTE + RCSA + RD Where; RCA = Re = 2.0 psi (pounds per square inch)
RMTE = (ICTe2 + ICRe2)1/2
=
(2.02 + 2. 02)1/2
2.83 psi RCSA = Ab = 2.0 psi RD = De = 2.0 psi T
2.0 + 2.83 + 2.0 + 2.0 psi T=
8.83 psi E-2
The determination of T2 involves the evaluation of a trigger value based on a loop total allowance or limit.
Since this switch trip function is anticipatory in that it is not assumed to occur in any of the Chapter 15 accident analysis, the determination of T2 is not applicable.
Therefore, the Allowable Value is calculated based on using T1.
Allowable Value = 45 -
8.83 psi
= 36.17 psig Based on the above, the more restrictive Allowable Value of 39.5 psig determined by using the TVA methodology will be used for conservatism.
- 2.
"Safety Limit-Related Determination: Provide a statement as to whether or not the setpoint is a limiting safety system setting for a variable on which a safety limit (SL) has been olaced as discussed in 10 Code of Federal Regulations (10CFR) Section 50.36(c)(ii)(A).
Such setpoints are described as 'SL-Related,'
in the discussions that follow.
For each setpoint that you determined not to be SL-Relatecl, explain the basis for this determination."
Response
As stated in Final Safety Analysis Report Section 7.2.1.1.2, the involved switch trip function is anticipatory in that it is not assumed to occur in any of the Chapter 15 accident analysis.
Additionally, the TS Bases identifies the functional capability of this design as an enhancement fox the overall reliability of the Reactor Protection System.
Therefore, no safety limit is specified for the switch function.
The setpoint is not classified as a limiting safety system setting for a variable on which a safety limit aas been placed as discussed in 10 CFR 50.36(c)(1)(ii)(A).
- 3.
"For setpoints that are determined to be SL-Related: The Nuclear Regulatory Commission (NRC) letter to the Nuclear Energy Institute (NEI) Setpoint Methods Task Force dated September 7, 2005 (ML052500004), describes setpoint-related TS (SRTS) requirements that are acceptable to the NRC for instrument settings associated with SL-related setpoints.
Specifically: Part 'A' of the enclosure to the letter
- provides Limiting Condition for Operation notes to be added to the TS, and Part 'B' includes a checklist of the information -to be provided in the TS Bases related to the proposed TS changes.
Describe whether and how you plan to implement the SRTS requirements suggested in the September 7 letter.
11 you do not plan to adopt the suggested SRTS, then explain how you will ensure compliance with 10 CFR*
50.36 by addressing items 3b and 3c, below.
.5.
As-Found Setpoint Evaluation: Describe how surveillance test results and associated TS limits are used to establish operability of the safety system.
Show that E-3
this evaluation is consistent with the assumptions and results of the setpoint calculation methodology.
Discuss the plant corrective action processes (including plant procedures) for restoring channels to operable status when channels are determined to be
'inoperable,' or 'operable but degraded.'
If the requirements for determining operability of the instrument being tested are located in a document otler than the TS (e.g., plant test procedure) explain how the requirements of 10 CFR 50.36 are met.
^1. As-Left Setpoint Control: Describe the controls employed to ensure that the instrument setpoint, uporn completion of surveillance testing, is consistent with the assumptions of the associated analyses.
If the controls are located in a document other than the TSs (e.g., plant test procedure) explain how the requirements of 10 CFR 50.36 are met."
Response
As discussed in response to item 2, the setpoint is not
- ,L-related.
- 4.
'For setpoints that are not determined to be SL-related setpoints in response to question 2: Describe the measures to be taken to ensure that the associated instrument channel is capable of performing its specified safety functions in accordance with applicable design requirements and associated analyses.
Include in your discussion, information on the controls you employ to ensure that the as-left trip setting, after completion of periodic surveillance, is consistent with your setpoint methodology.
If the controls are located in a document other than the T'Ss (e.g., plant test procedure), describe how it is ensured that the controls will be implemented to satisfy operability
.requirements."
Response
Engineering design output Setpoint and Scaling Documents (SSDs) will specify the as-left calibration tolerance (Ab)
- Ifor the trip setting as evaluated within TVA calculation
- E-DQ00004720050001 RO.
Periodic plant surveillance xnstructions will incorporate the as-left calibration tolerance values ensuring compliance with the design basis
- requirements defined within the SSDs.
The channel
- Iunctional test requirement for the involved loops is defined within TS Table 4.3-1 as prior to each reactor startup unless performed within the previous 31 days. The plant surveillance requires the setpoint to be returned to within the specified acceptable as-left calibration tolerance if found outside this allowance during performance of the channel functional test.
E-4