ML20151N942
| ML20151N942 | |
| Person / Time | |
|---|---|
| Site: | Sequoyah  |
| Issue date: | 08/04/1988 |
| From: | Gridley R TENNESSEE VALLEY AUTHORITY |
| To: | NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM) |
| References | |
| RTR-NUREG-1232 NUDOCS 8808090144 | |
| Download: ML20151N942 (11) | |
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TENNESSEE VALLEY AUTHORITY CHATTANOOGA. TENNESSEE 374o1 SN 157B Lookout Place August 4, 1988 U.S. Nuclear Regulatory Commission ATIN: Document Control Desk Washington, D.C.
20555 Gentlemen:
In the Matter of
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Docket Nos. 50-327 Tennessee Valley Authority
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50-328 SEQUOYAH NUCLEAR PLANT (SQN) UNIT 1 - ELECTRICAL CALCULATION PROGRAM STATUS
References:
1.
NRC letter to TVA dated May 18, 1988, "Safety Evaluation Report on the Tennessee Valley Authority Sequoyah Nuclear Performance Plan (NURFG 12W, Volume 2! '
2.
TVA letter to NRC dated February 18, 1988, "Sequoyah Nuclear Plant. (SQN) - Electrical Calculations - Revised Final Status for Unit 2 Restart" Tais letter provides NRC with the status of the electrical calculation program associated with the SQN unit I restart effort and its results. provides the background for TVA's development of the electrical calculation program for unit I restart and addresses some specific NRC concerns regarding the general adequacy of the electrical program for two-unit operation and deficiencies identified and corrected for unit 2 restart but not for unit 1. provides a listing and status of the electrical pot.er systems (EPS), instrumentation and control (16C) systems, and raceway systems calculations.
Furthermore, enclosure 2 provides a discussion of the computer s 'tware used in the auxiliary power system calculations. As noted wit'..a the enclosure, the decision to utilize this sof tware was based on 'IVA's comuitment to standardiza calculational methods and to use industry proven / Quality Assurance (QA) approved sof tware in order to produce technically superior calculations that may be readily accessed and easily maintained. The discussion of the software's applications is supplemented by the information concerning the software's acceptability for use, which is providc3 in enclosure 4. provides the current status and schedule of implementation of identified deficiencies associated with the electrical calculation program effort.
Further deficiencies identified in completion of this program will be disposition +1 in accordance with TVA's Nuclear Engineering Procedure (NEP) 9.1, and corrective action will be scheduled 90p 1
accordingly.
g 8808090144 880304 PDR ADOCK 05000327 POC p
An Equal Opportunity Employer
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- U.S. Nuclear Regulatory Commission In conclusion,- TVA has completed a major portion of the effort associated
- with the SQN unit 1 electrical calculation program. The basic elements that NRC approved for the unit.2 restart effort have been maintained and enhanced in some areas by the use of industry proven /QA approved software. All calculations are complete except "ELMSAC" which will be
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issued by August 24,1988. The final status and results of the program will be forwarded to NRC upon cm pletion of the program. contains the commitment made by this letter. Please direct any questions concerning this issue to Barry A. Kimsey at (615) 870-6847.
Very truly yours, TENNESSEE V L AUTHORITY
/.
R. G idley, clana r Nuclear Licensi and Regulatory Affairs Enclosures cc (Enclosures):
Ms. S. C. Black, Assistant Director for Projects TVA Projects Division U.S. Nuclear Regulatory Commission One White Flint, North 11555 Rockville Pike Rockville, Maryland 20852 Mr. F. R. McCoy, Assistant Director for Inspectica Programs TVA Projects Division U.S. Nuclear Regulatory Commission Region II 101 Marietta Street, NW, Suite 2900 Atlanta, Georgia 3P323 Sequoyah Resident Inspector Sequcyah Nuclear Plant 2600 Igou Ferry Road Soddy Daisy, Tennessee 37379 6
i
y ENCLOSURE 1 Electrical Calculation Program Status For SQN Unit 1 Restart In support of SQN unit 2 restart, TVA developed an electrical calculations program consisting of the following elements:
Identification, performance, and independent review of the essential minimum set calculations, i.e., those calculations required to support the design bases of the nuclear unit (s).
Docmentation of system deficiencies identified by the calculations, including determination of root cause, corrective action, and action to prevent recurrence.
Schcduling and/or performance of identified corrective actions.
-l Development and implementation of a change control process to ensure continuing calculation maintenance for design changes.
Development of an electrical calculatiene, training program to foster technical expertise, responsiveness, and cons _istency of calculation methods.
NRC documented in NUREG-1232, Volume 2, page 2-16, (reference 1):
"Based on its review of TVA's minimum set calculation program, the staff concludes that the program has resulted in a group of electrical calculations sufficient.ly complete, technically correct, current and retrievable to to suppc rt restart of Unit 2."
While the staff verified the sufficiency of SQN's electrical calculations effort for SQN unit 2 restart, they further noted that "... this conclusion of general adequacy of the electrical calculation program does not extend to Unit I restart" for the following reasons:
- "A number of calculations do not assume two unit operation and require upgrading to suppor) UtGt 1 operation."
"A number of deficiencies identified as required for restart have been completed for Unit 2, but not for Unit 1."
To demonstrate the adequacy of the electrical calculations program for unit I restart, it is both necessary and sufficient to demonstrate that the two preceding staff concerr.s have been fully addressed. This.s being accomplished by documenting that:
All unit 1 specific essential minimum set calculations have been issued and that all calculations that assume unit 1 in mode 5 have been revised to adequately address two-unit operation, and
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e e All-deficiencies applicable-to unit I restart have been resolved or are-presently scheduled for completion before restart of the unit.
These-two items shall be addressed separately for EPS, I6C systems, and raceway systems calculations. A list of these associated calculations, their status, and justification of their adequacy for unit I restart is contained in. enclosure 2.
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e ENCLOSURE 2 EPS Calculations I6C Systems Calculations and Raceway System Calculations Because TVA has programmatically addressed continuing calculation maintenance (i.e., calculation revision due to design modifications, through the development of a change control process), the units 1 and 2 calculations revised solely for this reason shall neither be identified nor addressed in the following.
In all instances system adequacy has been maintained.
1.
EPS CALCULATIONS The EPS calculations consist of two subcategories: cantrol power system (CPS) and auxiliary power systems (APS) analyses.
CPS Calc.ulations Calculation SQN-SBMG-1, revision 6, was revised to incorporato a revised unit 1 submerged equipment list.
The calculation methods and assumptions are unchanged from the previous revision reviewed by NRC.
Also, the results continue to demonstrate that submergence of the identifled electrical components will not prevent the Class 1E 120 volts (V) alternating current and 125 V direct current CPS from performing their intended safety functions.
All remaining SQN unit 2 restart CPS calculations were initially performed assuming two-unit operation; thus, no revisions beyond routine maintenance were required to support unit 1 restart.
APS Calculations The following is a list and summary of results of APS criculations initially issued or revised specifically to support SQN unit I restart. A detailed description of the following computer software selection is contained in enclosure 4.
A.
EEB-SQN-MS-T105-0001, REVISION 0 (TEL\\S)
TVA Electrical Auxiliary System (TELAS) is a QA load and cable computer data base program.
Data from this program is utilized in the El.ectrical Load Monitoring System (ElliSAC) (see item 2, page
- 2) and has been issued.
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1 B.
EEB-SQN-MS-TIO6-002, REVISION 0 (ED6AC)
EDGAC ia a QA load-flow-computer program that performs APS loading, voltage, and short-circuit analyses.
The decision to utilize EDEAC in support of unit I restart was based upon TVA's long-term commitment to standardize calculation methods and to use industry-proven QA software to produce technically superior calculations that may be readily accessible and easily maintained.
EULISAC will be issued by August 24, 1988.
The software previously utilized for NRC Branch Technical Position PSB-1 verification tests (VNEW and RADIAL) will be replaced by EDiSAC. TVA has performed a preliminary analysis using the July 12. 1980 test configuration to demonstrate that there is no appreciable difference in the calculated voltages of the software used and that ED6AC results are within 3 percent of measured values.
Preliminary results verify that ELMSAC is within the required 3 percent of measured values and is also within 0.5 percent of previously calculated RADIAL values.
Final results of this effort will be documented in the issuance of ELMSAC.
C.
SQN-E3-002 (Diesel Generator (DG] Analysis)
For SQN unit 2 restart, TVA performed calculation SON-E3-002 to determine and evaluate the loading (kilowatt and kilovar) on the standby DG at each sequence step for the following conditions:
1.
Blackout, loss of offsite power.
2.
Blackout with safety injection (SI) signal containment isolation phase A.
3.
Blackout with safety iniection (SI) signal containment isolation phase B.
In this analysis, DG 2B was modeled because it was determined to be the worst case sequential loading for each of the foregoing conditions.
Furthermore, unit I was considered in mode 5 with a blocked SI signal.
The results of this analysis verified that DG 2B has adequate capacity for the three accider.t cases given that Operations may have to take action to reduce the Steady-state loading for condition 3, before manual addition of loads in accordance with abnormal Operating Instruction A01-35.
TVA has revised this calculation to address power trains 1A,1B, 2A and 2B in support of unit I restart. The results of this revision confirms the diesel generators capability to perform the intended safety function within the manufacturer's rating.
- Thus, the revised calculation verifies DG adequacy for two-unit operation given the aforementioned restrictions.
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D.
D2SDJ-P213350 (Analysis of the APS for' Appendix R)
This calculation was revised to update the unit 1 portion of the analysis to the as-constructed status of the plant as required by the Nuclear Performance Plan. All-changes were documentation only and did not affect the results of the analysis.
E.
'SQN-APS-003 (480-V, APS Class 1E, Load Coordination Study)
This calculation was revised to update the unit 1 portion of the.
analysis to ensure the as-constructed status of the plant was modeled as required by the Nuclear Performance Plan. The i
following loads were determined to have long delay pickup settings that fall below the minimum criteria of 125 percent _of motor full load current:
480-V Shutdown Board / Component Load IB2-B/1D Control room air handling unit B-B 1B2-B/3D Shutdown Board Room Water Chill Package B-B 2B2-B/2B Electric Board Room A/C Compressor B-B A condition adverse to quality report (CAQR) has been initiated and will be dispositioned before unit I restart.
II.
16C CALCULATIONS The following IEC calculations have been revised to unit 1 operation.
These calculations were previously issued and reviewed by NRC for unit 2 restart. No revisions to methodology or assumptions have been made; the calculation scope has merely been extended to address unit 1 components / operation.
No.
Title 0002B Solenoid Valve Arc Suppression Networks Located in liarsh Environments 012 Instrument Accuracy Calculation 0-TS-12-91A, 91B through 99A, 99B (This calculation was revised to remove a unit 1 unverified assumption.)
032 Instrument Accuracy Calculation 1-Ff-3-147,155, 163, 170 (This calculation was revised to remove a unit 1 unverified assumption.)
041 Instrument Accuracy Calculation, UV Relay 046-05 Pre-Op Test in Lieu of Calculations for Control Loops s
1 046-06 Response Time of Sensing Lines 0070 Demonstrated Accuracy Calculations for 0-RE-90-106A, -102,
-103 and 1,2-RE-90-106A, B and -112A, B 1
(this calculation was revised to provide a justification for interim operation for a unit 1 unverified assumption--a similar procedure was employed for unit 2 operation and accepted by NRC) 074 Steam Generator Narrow Range Level Calibration (revised to incorporate unit 1 "as-constructed" data) 086 Demonstrated Accuracy Caiculation for AGASTAT Relays for Containment Air Return Fans 1A-A, IB-B 087 Time Delay Relays for ERCW IIcader Isolation Valves 093 Demonstrated Accuracy Calculation for 2-FT-7081E (this calculation was revised to address the corresponding unit 1 component)
The following calculations have been issued subsequent to the February 18, 1988 letter to NRC from TVA (reference 2) that documented the unit 2 restart calculations status. These calculations were issued to address NRC audit comments, independent design inspection (IDI) findings, CAQRs, etc., as indicated below. The calculations document and verify corrective actions and do not in themselves identify additional deficiencies or require additional modifications.
No.
Title _
092 Demonstrated Accuracy Calculation "R5" (timers) (This calcuiation was issued to address NRC concerns on timer accuracy expressed in the June 1, 1987 calculation audit.)
095 Demonstrated Accuracy Calculation on 62 Time Delay Relay (same as 092 above) 100 Demonstrated Accuracy Calculation on 2-TS-30-104 (This calculation was issued to address CAQR SQP880101 in which TVA's Environmental Qualification Project reclassified a formerly mild environment to harsh environment.)
101 Demonstrated Accuracy Calculation for PS-43-200A (This calculation was issued to address CAQR SQP871652 written to document a hydrogen analyzer hardware deficienty--the corrective action resulted in the reclassification of the subject pressure switch es safety-related and required for containment isolation, thus requiring a new deuonstrated accuracy calculation.)
, 102 Demonstrated Accuracy Calculation for 62/172 (same as 092, above) 103 Demonstrated Accuracy Calculation ACTD (Time Delay for Isol Viv 0-FCV-67-205, -208) (This calculation was issued to address IDI Finding D2.2-5.)
109 ABGTS-July (This calculation was issued to address CAQR SQP880441, which documented an Environmental Qualification binder deficiency--the binder incorrectly stated that no calculation was required for TS-30-14),156.)
All remaining SQN unit 2 restart I6C calculations were initially performed to support two-unit operation; thus, no revisions beyond routine maintenance were required to support unit I restart.
Note: Those calculations issued / revised for ongoing design activities (engineering change notices [ECNs], design c. ange notices [DCNs),
etc.) are not addressed in this listing but are programmatically covered by the design change process.
III. RACEWAY SYSTEMS CALCULATIONS All SQN raceway systems calculations were initially perforced in support of two-unit operation for unit 2 restart; thus, no revisions beyond routine maintenance were required to support unit I restart.
Note: Those calculations issued / revised for ongoing design activities (ECNs, DCNs, etc.) are not addressed in this listing but are programmatically covered by the design change process.
IV.
CONCLUSIONS Upon issuance of the calculation EEB-SQN-MS-TIO6-002 (ED! SAC) and re3olution of all identified corrective actions, TVA concludes that:
All essential minimum set electrical calculations required to support the design bases of SQN for two-unit operation have been identified, performed, reviewed, and issued.
All safety-related electrical systems are adequately designed and constructed to perform their required safety functions for two-unit operation.
In summary, the electrical calculations program has resulted in a group of electrical calculations sufficiently complete, technically correct, current, and retrievable to support SQN two-unit operation.
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ENCLOSURE 3 Status of Identified Deficiencies Including Significant Conditicn Reports (SCRs)
CAQRs And Problem Identification Reports (PIRs)
STARIS OF IDENTIFIED DEFICIENCIES (SCRs/CAQRs/PIRs)
The SQN Electrical Calculations Program Update submitted for NRC review by TVA letter dated February 18, 1988 (reference 2), documented the status of CAQRs, SCRs, and PIRs written as a result of the calculations program. The following documents the status of each deficiency applicable to unit I restart.
Number Statu_s SCR SQNEEB8607 R1 Fieldwork remaining:
scheduled for completion before unit I resta:-t SCR SQNEEB8532 R3 Fieldwork remaining:
scheduled for completion before unit I restart SCR SQNEEB8605 R1 Closed: no physical modifications required for units 1 or 2 SCR SQNEEB8629 R4 Fieldwork remaining:
scheduled for completion before unit 1 restart SCR SQNEEB8665 R0 Liased SCR SQNEEB8523 R0 Nonrestart for units 1 and 2 SCR SQNEEB8676 R0 Closed: A calculation revised before unit 2 restart demonstrated that no condition adverse to quality existed PIR SQNEEB8666 R0 Nonrestart for units 1 and 2: Unit board circuit breaker modification SCR SQNEEB86124 R0 Closed CAQR SQT870791 R0 Closed: no physical codifications rcquired SCR SQNEEB86131 R0 Closed: not a condition adverse to quality. Additional vendor data supported system adequacy for use "as-is"
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- Number Status SCR SQNEEB36167 R3 Closed PIR SQNEEB8668 R0 Closed SCR SQNEEB8628 R0 Closed PIR SQNEEB8683 R0 Nonrestart for units 1 and 2 SCR SQNEEB8667 R0 Nonrestart: Unit 2 and common items addressed before unit 2 restart.
Remaining work is nonrestart for unit 1.
SCR SQNEEB8673 R0 Closed SCP. SQNEEB8691 R0 Closed SCR SQNEEB8689 R0 Closed SCR SQNEEB8690 R0 Closed CAQR SQP871608 R0 Closed CAQR SQP871629 R0 Docunentation only work remaining:
scheduled for completion before unit I restart CAQR SQP871631 R0 Nonrestart for units 1 and 2.
Operational history and modes indicate no fieldwork required.
CAQR SQP871644 RO Fieldwork remaining:
scheduled for completion before unit I restart The list, description, and status of deficiencies documented in the February 18, 1988 letter to NRC from TVA (reference 2) defined the program status as of January 26, 1988.
Subsequent to that date, the following CAQRs have been issued and dispositioned/ resolved for unit 2 restart and are in progress for unit I restart in accordance with applicable TVA procedures.
Number Status CAQR SQP880204 R1 This CAQR describes a failure to adequately document a calculation assumption. The resolution of the CAQR is a documentation-only revision to the calculation and is scheduled for completion before unit 1 restart.