ML050180366
| ML050180366 | |
| Person / Time | |
|---|---|
| Site: | Sequoyah  |
| Issue date: | 01/19/2005 |
| From: | Pickett D NRC/NRR/DLPM/LPD2 |
| To: | NRC/NRR/DLPM |
| Pickett , NRR/DLPM, 415-1364 | |
| References | |
| TAC MC4408, TAC MC4409 | |
| Download: ML050180366 (3) | |
Text
January 19, 2005 MEMORANDUM TO:
FILE FROM:
Douglas V. Pickett, Senior Project Manager, Section 2
/RA/
Project Directorate II-2 Division of Licensing Project Management
SUBJECT:
DOCUMENTATION OF REQUEST FOR ADDITIONAL INFORMATION PROVIDED TO SEQUOYAH NUCLEAR PLANT, UNITS 1 & 2 (TAC NOS. MC4408 AND MC4409)
The purpose of this memorandum is to document a request for additional information that was transmitted electronically to the licensee and subsequently modified as a result of two telephone conference calls between the staff and the licensee.
By letter dated August 14, 2004 (TVA-SQN-02-01, Revision 1), Tennessee Valley Authority submitted proposed changes to the Sequoyah Nuclear Plant Technical Specifications that would revise the trip setpoint column of the Reactor Protection System and Engineered Safety Features Instrumentation tables to utilize a nominal setpoint value and revise the associated Bases. The proposed allowable values were calculated using Method 3 of Instrument Society of America Standard S67.04.
The two questions in the Attachment were prepared by the Instrumentation & Controls Section of the Division of Engineerings Electrical and Instrumentation & Controls Branch. The questions were transmitted electronically to the licensee on December 20, 2004. Telephone conference calls between the staff and the licensee were subsequently held on December 22, 2004 and January 6, 2005. As a result of these conference calls, the staff decided to delete Question 2 of the Attachment. Agreement was reached that the licensee would respond to Question 1.
Docket Nos. 50-327 and 50-328
Attachment:
As stated
January 19, 2005 MEMORANDUM TO:
FILE FROM:
Douglas V. Pickett, Senior Project Manager, Section 2
/RA/
Project Directorate II-2 Division of Licensing Project Management
SUBJECT:
DOCUMENTATION OF REQUEST FOR ADDITIONAL INFORMATION PROVIDED TO SEQUOYAH NUCLEAR PLANT, UNITS 1 & 2 (TAC NOS. MC4408 AND MC4409)
The purpose of this memorandum is to document a request for additional information that was transmitted electronically to the licensee and subsequently modified as a result of two telephone conference calls between the staff and the licensee.
By letter dated August 14, 2004 (TVA-SQN-02-01, Revision 1), Tennessee Valley Authority submitted proposed changes to the Sequoyah Nuclear Plant Technical Specifications that would revise the trip setpoint column of the Reactor Protection System and Engineered Safety Features Instrumentation tables to utilize a nominal setpoint value and revise the associated Bases. The proposed allowable values were calculated using Method 3 of Instrument Society of America Standard S67.04.
The two questions in the Attachment were prepared by the Instrumentation & Controls Section of the Division of Engineerings Electrical and Instrumentation & Controls Branch. The questions were transmitted electronically to the licensee on December 20, 2004. Telephone conference calls between the staff and the licensee were subsequently held on December 22, 2004 and January 6, 2005. As a result of these conference calls, the staff decided to delete Question 2 of the Attachment. Agreement was reached that the licensee would respond to Question 1.
Docket Nos. 50-327 and 50-328
Attachment:
As stated Distribution:
PUBLIC PDII-2 r/f DPickett EMarinos MMarshall BClayton VMcCree, R2 SRhow ADAMS ACCESSION NO. ML050180366 NRR-106 OFFICE PM:LPD2-2 LA:LPD2-2 SC:LPD2-2 NAME DPickett BClayton MMarshall DATE 01 / 19 / 05 01 / 19 / 05 01 / 19 / 05 OFFICIAL RECORD COPY
SEQUOYAH NUCLEAR PLANT, UNITS 1 AND 2 DOCKET NOS. 50-327 AND 50-328 REQUEST FOR ADDITIONAL INFORMATION NOMINAL TRIP SETPOINTS FOR RPS AND ESF INSTRUMENTATION ELECTRICAL AND INSTRUMENTATION & CONTROLS BRANCH 1.
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.
2.
The minimum operable channels for the auxiliary feedwater and emergency diesel generator loss of power start timers are proposed to change from 2 per shutdown board to 1 per shutdown board. This timer in conjunction with voltage senors functions to actuate the loss of power start of the AFW pumps and EDGs and load shed initiation after the detection of low voltage. The voltage sensors for each train are arranged in a two-out-of-three logic and provides a redundant feature. However, the timer does not have a redundant feature to meet the single failure criteria. The staff requests justification that 1 timer satisfies all accident mitigation requirements associated with AFW and EDG starts and maintains single failure protection.
ATTACHMENT