ML19332C853
| ML19332C853 | |
| Person / Time | |
|---|---|
| Site: | Sequoyah  |
| Issue date: | 11/21/1989 |
| From: | Shell R TENNESSEE VALLEY AUTHORITY |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| NUDOCS 8911290081 | |
| Download: ML19332C853 (4) | |
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M %.:c TENNESSEE VALLEY AUTHORITY-
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- CHATTANOOGA.' TENNESSEE 37401 P
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~ l' U.S. Nuclear Regulatory, Commission ATTN:: Document Control Desk L ashington,- D.C..-20555:
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,f Gentlemen:-
j Inithe Matter of-
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Docket Nos. 50-327-Tennessee' Valley Authority
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50-3?8-SEQUOYAH NUCLEAR PLANT (SQN) - RE'/ISED COMMITMENT ASSOCIATED WITH NRC OBSERVATIONS EEB-10 AND.EEB-11
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Reference:
TVA' letter to NRC dated January-19, 1988, "Sequoyah Nuclear Plant-(SQN) - TVA Division of Nuclear Engineering (DNE) Calculation-Effort" In the referenced letter respending to NRC observations originating in eight 3
-previous NRC'inspectlon reports (NRC Report'Nos. 50-327,=328/86-27, 86-38, 86-45, 86-55, 87-06, 87-14, and 87-27), TVA committed to evaluate-the calculai:lons associated with Observations EEB-10 and EEB-ll involving pump-start time delay relay setpoint calculations and. component coo 61ng. system i
..setpoint coordination, respectively.
.The' enclosure provides SQN's technical evaluation of the calculations-associated with EEB-10 and EEB-11.
If you have any questions concerning this submittal, please telephone
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M.~A. Cooper at-(615) 843-6651.
Very truly yours, TENNESSEE VALLEY AUTHORITY f,
knager,NuclearLicensingand Regulatory Affairs Enclosure cc:
See page 2 8911290081 891121 k D DR ADOCK 0500 7
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'.An Equal Opportunity Employer
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q-U.S. Nuclear Regulatory Commission I"
NOV 21:1989 L,
cc.(Enclosure):
Ms. S. C. Black,-Assistant Director-i for Projects lTVA Projects Division U.S. Naclear Regulatory Commission =
10ne White Flint, North 11555 Rockville Pike Rockville, Maryland.' 20852 Mr. 8. A. Wilson,~. Assistant Director
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for Inspection Programs TVA Projects Division E.
U.S.: Nuclear Regulatory Commission-
~ Region II 101.Marietta Street, NW, Suite 2900 Atlanta, Georgia 30323 NF.C. Resident Inspector Sequoyan Nuclear Plant-2600 Igou Ferry Road Soddy Daisy, Tennessee 37379 E
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c Enclosure The following includes'the-NRC's observation, TVA's response to the observations, and TVA's justification of how the commitments have been completed.
Observation EEB Pump Start Time Delay Relay Setpoint Calculations
-Using the Calculation Cross Reference Information System (CCRIS) database output, the team determined that no calculations had been prepared to support the setpoint or accuracy of 15 to 25 second and 0.5 second time delay relays used in pump start-circuits for the ERCW, CCS, and AFH systems.
During the inspection, EEB stated that they are not preparing setpoint calculations for some of the safety-related time delay relays. There is no indication-that all safety-related time delay relays will be addressed.
This item is also v'ewed by the team as an indication of a coordination problem between EEB and AEB with regard to instrument setpoint calculations."
Response
As discussed with NRC, the pump start time delay relay setpeint calculations i
required for restart have been issued.
The postrestart calculations are scheduled for completion by June 30, 1989.
TVA has issued Nuclear Engineering Procedure (NEP) 3.12, " Safety-Related Setpoints for Instrumentation and Control - Establishment and Validation." NEP-3.12 provides the requirements I
and responsibilities for the establishment, coordination, and validation of s
all safety-related setpoints.
f Completed Actions The calculation to support the setpoint or accuracy of 15-to 25-second, time-delay relays used in pump start circuits for the essential raw cooling water, component coolant system (CCS), and auxiliary feedwater (AFH) systems was prepared and issued as " Demonstrated Accuracy Calculation - Diesel Generator Time Relays."
i It has been determined that a calculation for the 0.5-second, time-delay relay 2
is not required based on the following justification.
The 0.5-second, time-delay relays were originally used to reset the sequential timers in the event an' accident occurred after loss of offsite power.
This accident sequence is no longer considered by TVA, as stated in TVA's letter to NRC 1
There are two diesel generator (D/G) loading sequences dated March 12, 1987. -
currently considered: one, which is applied on the loss of voltage on the 6.9-kilovolt (kV) shutdown board but in the absence of a safety injection signal (SIS), "the nonaccident condition"; and the other, which is applied i
when an SIS is received coincident with a sustained loss of voltage on the
- 6.9-kV shutdown board, "the accident condition." The 0.5-second, time-delay
~ relays are not required for either of these sequences.
For the " accident condition," SIS coincident with a sustained loss of voltage 1
on the 6.9-kV shutdown board, the 0.5-second, time-delav relay actuates concurrent with the starting of the D/Gs; however, no change to the engineered safety feature (ESF) logic results.
The sequence of the ESF loads does not start until the D/G conrects to the 6.9-kV shutdown board, which takes at least 8.5 seconds.
Thus, the 0.5 second tims delay and timer accuracy are not a consideratini when compared with the 8.5-second, 10-second nominal, D/G
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start time.
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i Based on'this techni' cal justification, observation EEB-10 does not require any l
further action and is' considered complete.
' Observation EEB-?1 - Component Cooling System Setpoint Coordination i
U "CCS flow switch setpoint calculation B44 MEB 870602 001 included records of telephone'dit,cussions between MEB and EEB regarding flow alarm accuracy-values,.but additional information to technically justify the selection of these values wasLnot documentea.
This item is also viewed by the team as an indication of coordination problem between EEB and MEB with regard to r
instrument setpoint calculations."
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Response
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As' discussed with NRC, the CCS'setpoint calculations required for restart have been issued. The postrostart calculations are scheduled for completion by June 30, 1989.
Completed Actions
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TVA~has evaluated its calculation for component cooling system flow switch setpoints. This calculation documents the setpoints and error. range for the
'l following Flow Switches:
1-FS-70-142, 1-FS-70-176, 1-FS-70-'170, 2-FS-70-170, 2-FS-70-190, and 2-FS-70-164A.
The error ranges identified represent i
instrument loop error. Although documentation does not exist supporting the 1
' basis of the error range valve selection, the indicated error ranges are consistent with typically provided vendor data.
These switches are non-safety-related, receive nondivisional power, and are not required to be operational during or after any FSAR, Chapter 15, accident.
The CCS Flow Switch 1-FS-70-142 alarms on low reactor building supply header flow: 1-FS-70-176 alarms on low seal water heat exchanger A outlet flow; j
1-FS-70-170 and 2-FS-70-170 alarm on low boric acid gas stripper evaporator heat exchanger outlet flow; 2-FS-70-164A alarms on low miscellaneous equipment supply. header flow; and 1-FS-70-190 alarms on low nonregene a tive letdown heat l
. exchanger outlet flow. These alarm are not safety-related and do not require detailed accuracy calculations.
Additionally, these switches receive periodic calibration in accordance with SI-582, " Periodic Calibration of Component Cooling Water System."
i Based on this information, the SQN evaluation has concluded that no further i
calculations are required to support the setpoint accuracy for the described
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flow switches.
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