ML051190262
| ML051190262 | |
| Person / Time | |
|---|---|
| Site: | Sequoyah  (DPR-077, DPR-079) |
| Issue date: | 04/11/2005 |
| From: | Pace P Tennessee Valley Authority |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| TVA-SQN-TS-02-01 | |
| Download: ML051190262 (6) | |
Text
Tennessee Valley Authority, Post Office Box 2000, Soddy-Daisy, Tennessee 37384-2000 April 11, 2005 TVA-SQN-TS-02-01, Revision 1 10 CFR 50.90 U.S. Nuclear Regulatory Commission ATTN:
Document Control Desk Washington, D. C. 20555-0001 Gentlemen:
In the Matter of Tennessee Valley Authority
)
Docket Nos. 50-327
)
50-328 SEQUOYAH NUCLEAR PLANT (SQN)
UNITS 1 AND 2 -
TECHNICAL SPECIFICATIONS (TS)
CHANGE 02-01, REVISION 1, RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION (RAI)
Reference:
TVA letter to NRC dated August 18, 2004, "Sequoyah Nuclear Plant (SQN) -
Units 1 and 2 -
Technical Specification (TS) Change 02-01, Revision 1, Nominal Trip Setpoints for Reactor Protection System (RPS) and Engineered Safety Features (ESF) Instrumentation" This letter responds to requests for additional information associated with the referenced TS change request.
Telephone conversations were held with NRC personnel on December 22, 2004, January 6, 2005, February 16, 2005, and March 10, 2005.
These conversations clarified the information needed to complete the processing of the proposed TS change.
The enclosure provides the question to be addressed and TVA's response to this question.
There are no commitments contained in this letter.
A-D PNfled,n 9ecycWW pawe
U.S. Nuclear Regulatory Commission Page 2 April 11, 2005 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 11th day of April, 2005.
Sincerely, P.
Pace Manager, Site Licensing and Industry Affairs
Enclosure:
Response to Request for Additional Information Enclosure cc (Enclosure):
Framatome ANP, Inc.
P. 0. Box 10935 Lynchburg, Virginia 24506-0935 ATTN:
Mr. Frank Masseth 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 08G9 One White Flint North 11555 Rockville Pike Rockville, Maryland 20852-2739
ENCLOSURE TENNESSEE VALLEY AUTHORITY (TVA)
SEQUOYAH NUCLEAR PLANT (SQN)
UNITS 1 AND 2 NRC Requested Information:
The proposed allowable values (AV) are calculated by using Method 3 of ISA S67.04.
However, the licensee states that the proposed setpoint and allowable value would meet Method 1 requirements.
The total loop uncertainty value is the statistical combination of all uncertainties of a given instrument channel.
The channel operational test (COT)/channel functional test (CFT) uncertainty is the statistical combination of all uncertainties associated with those instrument channel components that would be tested during the COT/CFT which may include instrument drift, instrument reference accuracy, and setting tolerance.
The staff requests the analytical limits (AL) and the calculation accounting for all uncertainties not measured during COT/CFT to confirm that the proposed allowable values meet Method 1 requirements. An acceptable method (i.e., Method 1) for deriving the AV will require an independent calculation (check calculation) that will assure that the margin between the AV and AL would include all the uncertainties not measured during COT/CFT.
TVA Response:
In accordance with SQN's Westinghouse Electric Company setpoint methodology, the channel statistical allowance (CSA) for an instrumentation loop is defined by the following equation:
CSA = EA +{(PMA)2+ (PEA)2+ (SCA+SMTE+SD) 2 + (SPE) 2 + (STE) 2
+(RCA+RMTE+RCSA+RD) 2+ (RTE) 2 ) 1/2 The error terms for the above equation as defined by SQN's Westinghouse setpoint methodology are:
environmental allowance (EA) process measurement accuracy (PMA) primary element accuracy (PEA) sensor calibration accuracy (SCA) sensor measurement and test equipment accuracy (SMTE) sensor drift (SD) sensor pressure effects (SPE) sensor temperature effects (STE) rack calibration accuracy (RCA) rack measurement and test equipment accuracy (RMTE)
E-1
rack calibration setting accuracy (RCSA) rack drift (RD) rack temperature effects (RTE)
The Allowable Value (Av) is defined by the Westinghouse methodology as:
Av = Setpoint -
the lowest (most restrictive) of the values T1 or T2 T1 and T2 are referred to as the "trigger values" defined by SQN's Westinghouse setpoint methodology.
The T1 method involves the values used in the statistical calculation as follows:
T1 = (RCA+RMTE+RCSA+RD)
(Rack instrumentation uncertainties which are measurable during calibration)
The T2 method extracts these values from the calculation and compares these numbers statistically against the total allowance as follows:
T2 = TA-({A+(S)2} 2+EA) where; A =
(PMA)2 +(PEA)2+(SPE)2 +(STE)2 +(RTE) 2 S = (SCA+SMTE+SD)
TA = Total Allowance = Setpoint -
Reactor Trip Safety Limit Therefore, T2 = TA-[{ (PMA)2+(PEA) 2+(SPE)2 +(STE)2+(RTE)2
+ (SCA+SMTE+SD) 2}1 2+EA]
(Instrumentation uncertainties which are not measurable during rack calibration)
The instrumentation of concern for this technical specification (TS) submittal is located in an area not subjected to harsh environmental parameters of radiation and temperature from a design basis accident.
Therefore, the EA term of the equation is not applicable.
With margin, the above value for T1 was found to be the most restrictive or lowest of the two values and therefore, utilized to determine Av as follows:
Av = Setpoint-T1 Although these calculations use Method 3 from American National Standards Institute (ANSI)/Instrument Society of America (ISA)
S67.04, the T1 and T2 check calculations above show that the proposed setpoint and allowable value would meet the Method 1 requirements due to margin included between the setpoint and safety limit.
E-2
Operating Region Operating Region Setpoint Av minimum l Rack Measurables I
Rack Measurables l
-at calibration r
at calibration T2 Setpoint Av minimum Av maximum Margin Margin TA r
.1
.4-A hL Unmeasurables at rack calibration combined under the radical with rack measurables Safety Limit A
Avmaximum Unmeasurables at rack calibration combined outside the radical from rack measurables F
Safety Limit I
METHOD3 EZ~IZZ METHODI1 lI The Allowable Value (AV) used in the TS submittal is the minimum allowed for both methods. Therefore, the only difference between method 1 and 3 is the amount of margin between the safety limit and the setpoint.
E-3
Note 3: Radiation monitors have different accuracy parameters.
The following errors are associated with the detector (sensor) and are the only unmeasurable parameters during calibration.
Epc = Primary Calibration Error Eed = Energy Dependence Error Efac = Factory Alignment Error Combining these errors 1(0.042
+ 0.121
- 0.042 )
0.1348 V Safety Limit = 375.49 mR/hr Safety Limit = 2 (log(375.49) + 1) = 7.149 V Safety Limit -
Unmeasurables = 7.149 -
0.1348 = 7.0142 V Converting to mR/hr = i0{(7o0142/2) -
- 1) 321.44 mR/hr Difference from SL = 375.49 -
321.44 = 54.05 E-5