ML20203N911

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Nuclear Safety Review Staff Investigation Rept I-85-612-SQN, Employee Concern XX-85-020-001, RCS Pressurizer Relief Flow Control Valves - Failure to Make Torque Switch Bypass Mods, on 851015-17 & 860115-22
ML20203N911
Person / Time
Site: Sequoyah  Tennessee Valley Authority icon.png
Issue date: 03/06/1986
From: Alexander M, Mcclure R, Stevens W
TENNESSEE VALLEY AUTHORITY
To:
Shared Package
ML20203N908 List:
References
I-85-612-SQN, NUDOCS 8605060206
Download: ML20203N911 (8)
v • d • e


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TENNESSEE VALLEY AUTHORITY NUCLEAR SAFETY REVIEW STAFF NSRS INVESTICATION REPORT NO. I-85-612-SQN EMPLOYEE CONCERN XX-85-020-001 (SQN APPLICABILITY)

SUBJECT:

RCS PRESSURIZER RELIEF FLOW CONTROL VALVES - FAILURE TO MAKE TORQUE SWITCH BYPASS MODIFICATIONS DATES OF INVESTICATION: OCTOBER 15-17, 1985, and JANUARY 15-22, 1986 INVESTIGATOR: .[6mI O M. W. ALE'XAUDER DAtE '

REVIEWED BY: k * [- o4 3[ [

R. E. MCCLURE DATE APPROVED BY: N M '

/-et 3[Io/N W. D. STEVEUS DATE 7

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I. BACKCROUND A Nuclear Safety Review Staff (NSRS) investigation was conducted to determine the validity of an expressed employee concern as received by Quality Technology Company (QTC)/ Employee Response Team (ERT). The concern of record, as summarized on the Employee Concern Assignment Request Form from QTC and identified as KK-85-020-001, stated:

An ECN 0 5971 was issued at Sequoyah in 1979 that required a bypass of the over-torque limit switches on certain limitorque operators. It was recently discovered (3-4 months ago) that this had not boon accomplished for SIS valve # 332 and 333. CI is concerned about ECN's applicability to WBNP.

The ERT follow-up group was contacted to obtain additional clarification of the concern. No additional information was available.

II. SCOPE A. The scope of the investigation was determined from the stated concern of record to be that of two issues requiring investigation:

1. Were torque switch nodifications to the valve operator circuits on valves FCV-68-332 and FCV-68-333, which were required by a 1979 ECU, made? If not, what is the current status of these valves?
2. Is Watts Bar Nuclear Plant (WBN) aware of this potentiel probicm?

B. This investigation entailed the review of historical documentation related to motor operated valvo (MOV) problems including Nonconformanco Reports (NCRs), Engineering Change Noticos (ECNs),

drawings, and workplans. Cognizant TVA personnel were also interviewed.

ITI.

SUMMARY

OF FINDINCS A. Requirements and Commitments

1. ECN 2257, dated March 12, 1979, on modification to " active" MOV opccator circuits to address operational problems identified at Browns Ferry Nuclear Plant (BFN) (Ref. 2).
2. U.S. URC IE Circular 81-13, dated September 25, 1981, " Torque Switch Electrical Bypass Circuit for Safeguard Service Valve Motors," contains recommended actions for licenscos relative to assuring that required torque switch bypasses are installed and maintained properly (Ref. 9).

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I C C B. Findings

1. A review of historical documentation revealed that Sequoyah Nuclear Plant (SQN) ECN 2257 (Ref. 2) was issued in 1979 to address valve operator problems that had boon experienced at BFN. ECN 2257 required removing the torque switch from the i

opening circuits of all " active" valves and bypassing the closing torque switch with a closing limit switch. From the nature of the stated concern and the associated timeframe, it was assumed for purposes of this investigation that the CI meant ECN 2257 and not ECN 5971 (which was issued in 1983).

Furthermore, " SIS valves 332 and 333" were assumed to bo FCV-68-332 and FCV-68-333 which are RCS Pressurizer Relief Flow Control Valves, commonly called PORV block valves. These valves are in the Reactor Coolant System (RCS) and not in the Safety Injection System (SIS).

2. The "activo" valves referred to in ECN 2257 are "those valves whose operations are necessary to mitigate particular accident conditions." The " active" SQN valves required to be modified in accordance with ECN 2257 were identified to be the same valves as listed in WBN FSAR Tables 3.9-17 and 3.9-25 (earlier revision of Ref. 7) since the valve numbers are the same at both plants, and this valve list is not in the SQN FSAR. Approximately 222 valves were to be modified.
3. From information provided by reference 21 RCS Pressurizer Relief Flow Control Valves FCV-68-332 (both units) and FCV-68-333 (both units) were not identified as " active" valves in the initial WBN FSAR Tables 3.9-17 and therefore not required to be modified in accordance with SQN ECU 2257.

4 A review of documentation associated with implementation of SQN ECN 2257 [WP No. 2912 (Ref. 3) and WP No. 2963 (Ref. 4)]

indicated that several workplans were prepared to rework all the I valves identified in the WBN FSAR Tables 3.9-17 and -25.

5. In July 1983, during component Environmental Qualification (EQ) reviews it was determined that the limitorque motor operators on I the PORV block valves contained class B insulation which is not qualified for postaccident conditions inside containment per NUREG 0588 requirements. This condition was documented in NCR SQN HEB 8157 (Ref. 10), and operator replacement was recommended.
6. In October 1983, SQN ECH L5971 (Ref. 11) was prepared to evaluate and document the operator replacement for the PORV block valves.

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7. In January 1984, as a result of reviewing the WBN final design it was determined that 15 additional WBN valves (Refs. 21, 22, and 23) should be added to the WBN " active" valve list and should thorofore be subject to the torque switch bypassing initially required by SQN ECN 2257. Valves FCV-68-332 and FCV-68-333 were included in these additional valves. From a 5

review of reference 21, it appears this information was not made available to SQN.

8. In June 1984, workplans 11066 (unit 1 (Ref. 12)] and 11065

[ unit 2 (Ref. 13)] were prepared to replace the electric motor valve operators per SQN ECN L5971.

9. In November 1984, during the U2-C2 refueling outage, workplan 11065 was completed including quality control (QC) inspections and functional testing of the unit 2 valves.
10. On March 23, 1985, Shift Engineer and Unit Operator Logs (Ref. 17) indicate that 2-FCV-68-332 and 2-FCV-68-333 failed to close from the Main control Room hand switches during routine stroke testing (under operating conditions) in accordance with Surveillance Instruction (SI) 166.1 (Ref. 20). The valves could only be closed at the MOV boards. The valves were tagged out, and power was ecmoved. Potential Reportable Occurrence 2-85-045 and Commitment Action Tracking 85-163 were then initiated. Unit 2 continued to operate under Limiting condition for Operation (L.C.O.) 3.4.3.2 (Ref. 19) until the cause of the trouble could be dotermined and unit conditions permitted repair.
11. In early May 1985, unit 2 tripped off lino. The plant staff prepared Category D FCR 3489 (Ref. 14) to request that modifications be made to the valve operators for the pORV block valves (both units) to eliminate the function of the torque switches from the , opening circuit and bypass the closing torque switch with a limit switch. ECN L6416 (Ref. 15) was issued to revise the necessary drawings and document these modifications.
12. Workplan 11620 (Ref. 16) was pecpared to accomplish the torque switch modifications on both units per ECU L6416.
13. Also in May 1985, valve operator replacements for class A wiring on unit I were completed (with exceptions) in accordance with workplan 11066. The exceptions dealt with postponing postmodification functional testing which would be conducted under workplan 11620.
14. A review of completed workplan 11620 indicates that the modification to the motor operator torque switches por ECU L6416 was completed for both units including QC inspections and functional testing.

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15. A review of subsequent SI 166.1 test data showed that PORV block valves FCV-68-332 and FCV-68-333 nec functioning properly.

IV. CONCLUSIONS AND RECOMMENDATIONS A. Conclusions Although there are discrepancies in the employee concern as stated on the Employee Concern Assignment Request Form it is substan-tlated. FCV-68-332 and -333 were not included in initial torque switch bypassing requirements established in 1979 for WBN and SQN.

However, in January 1984, additional valves (including FCV-68-332 and -333) were added to the WBN " active" valvo list but apparently overlooked at SQN. Because of subsequent operational probicms at SQN, FCV-68-332 and -333 have now been appropriately modified.

Surveillance test data indicates the valves are functioning properly. From information reviewed in the courso of this investigation and discussions with cognizant TVA personnel, it appears that all WBN " active" valves have now been appropriately modified.

B. Recommendations I-85-612-SQU-01, Verification of SON " Active" Valve List Since there is a possibility that other important valves added to the WBN " active" valvo list were not considered at SQN, the SQN plant staff should verify that all SQU " active" valves requiring torque switch bypassing have been modified appropriately. Any difference between the list of WBN active valves and the list of SQU active valves should be justified. (P-1]

I-85-612-SQN-02, Document Failure to Adequately Identify "Activo" Valves OE should document by a significant condition report (SCR) the failure to adequately identify the required " active" valves at SQN.

Consider the SQN initial notification (ECN 2557), the apparent failure to notify SQN when WBU recognized the need to include an additional 15 valves, and when SQN FCR 3489 was approved. (P-2]

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DOCUMENTS REVIEWED IN INVESTICATION 1-85-612-SQN AND REFERENCES

1. SQN NCR 280 dated June 6,1977, evaluates swollen motor leads on limitorque valve operators
2. SQN ECN 2257 dated March 12, 1979, on modification to " active" MOV-operator circuits to address problems identified at Browns Ferry Nuclear Plant
3. SQN WP No. 2912 dated March 23, 1979, prepared by Construction to implement ECN 2257 for several system 63 (SIS) valves
4. SQN WP No. 2963 dated March 24, 1979, prepared by Construction to implement ECN 2257 for several system 63 (SIS) valves
5. SQN wiring diagrams revised by ECU 2257:

45N1750-14 R7 1-FCV-68-332 45N1749-14. B12 1-FCV-68-333 45N2750-14. R11 2-FCV-,8-332 45N2749-13, R11 2-FCV-68-333 '

6. SQU wiring diagrams for valves 332 and 333, current revision:

45U1750-14. R12 1-FCV-68-332 45N1749-14 R14 1-FCV-68-333 45U2750-14, R20 2-FCV-68-332 45U2749-13 R17 2-FCV-68-333

7. Watts Bar FSAR, Tables 3.9-17 and 3.9-25, as revised by Amendment 55
8. Design Change Request SQ-DCR-972 dated December 11, 1980, authorizing Engineering Design to proceed with necessary engineering and analysis required to meet environmental qualification requicements of NUREG 0588
9. U.S. NRC IE Circular 81-13 dated September 25, 1981, " Torque switch Electrical Bypass Circuit for Safeguard Service Valve Motors"
10. UCR SQN HEB 8157, R1, dated September 26, 1983, documents that internal wiring in the cicetric motor operators on valves FCV-68-332 and FCV-68-333 does not meet NUREC 0588 insulation requirements
11. SQN ECN L5911 dated October 7, 1983, evaluates electric motor operator replacement for FCV-68-332 and FCV-68-333
12. SQN WP !!o. 11066 dated June 25, 1984, covers replacement of valve operators on unit 1 e

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13. SQN WP No. 11065 dated June 25, 1984, covers replacement of valve operators on unit 2
14. SQN Category D FCR 3489, dated May 8, 1985, requested wiring changcc to FCV-68-332 and FCV-68-333 motor operators
15. SQN ECN L6416 dated May 8, 1985, evaluates wiring changes to FCV-68-332 and FCV-68-333 motor operators (both units)
16. SQN WP No. 11620 dated May 8, 1985, implements wiring changes called for in ECN L6416 (both units)
17. Shift Engineer and Unit Operator Logo for April and May 1985
18. U.S. NRC IE Bulletin 85-03 dated November 15, 1985, "Motoroperated Valves Common Mode Failures During Plant Transients due to Improper Switch Settings"
19. SQN Technical Specifications Limiting Conditions for Operation (L.C.O.)

. 3.4.3.2

20. SQN Surveillance Instruction (SI) 166.1, Revision 34, dated December 6, 1985, " Full Stroking of Category 'A' and 'B' Valves During Operation"
21. Informal com=unications from A. Heacock entitled " Active Valves"
22. WBN ECU 4551 (unit 1) dated January 26, 1984, adds 15 additional unit i valves (including FCV-68-332 and FCV-68-333) to the WBU " active" valve list
23. WBN ECU 4552 (unit 2) dated January 26, 1984, adds 15 additional unit 2 valves (including FCV-68-332 and FCV-68-333) to the WBu " active" valve list 9

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STATES GOVERN 3 TENT ap fs Memorandum TENNESSEE VALLEY AUTHORITY TO: H. L. Abercrombie, Site Director, Sequoyah Nuclear Plant FROM: K. W. Whitt, Director of Nuclear Safety Review Staff, E3A8 C-K DATE:

MAR 0 51986

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SUBJECT:

NUCLEAR SAFETY REVIEW STAFF INVESTICATION REPORT TRANSMITTAL m s :.' er n-

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Transmitted herein is NSRS Report No. I-86-180-SON -

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Subject SON DRAWING CONTROL

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Concern No. SOM-6-003-001: -002: -003: -004: -005: -O'dNC . - ._ -

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.i.;;a.p No response or corrective action is required for this reporN- It s e !_i ceid. i

transmitted to you for information purposes only. Should you have ..any
  • w questions, please contact W. D. Stevens at telephone 6231 Recomend Reportability Determination: Yes No X A --

\. \ .VJ Director, NSRS/ Designee WDS:GDM Attachment cc (Attachment):

W. C. Bibb, BFN

. W. T. Cottle, WB James P. Darling, BLN R. P. Denise, LP6N40A-C G. B. Kirk, SQN D. R. Nichols, E10A14 C-K QTC/ERT, Watts Bar Nuclear Plant Eric Sliger, LP6N48A-C J. H. Sullivan, SQN 10565U e

L ib p f C- R.... ! ? e es,..;,, ar Ro n ale T?on,rinvis. nn o f,o Pn,,rnli .Taroin ar Plan

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