ML20002D086
| ML20002D086 | |
| Person / Time | |
|---|---|
| Site: | Sequoyah  |
| Issue date: | 01/13/1981 |
| From: | Mills L TENNESSEE VALLEY AUTHORITY |
| To: | James O'Reilly NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II) |
| References | |
| 10CFR-050.55E, 10CFR-50.55E, NUDOCS 8101190388 | |
| Download: ML20002D086 (5) | |
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400 Chestnut Street Tower II January 13, 1981 g
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Mr. James P. 0 7e111y, Director
$ g 7 g gI, e Office of Inspec on and Enforcement U.S. huolear Regul 'ory Comission
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~C1 Yr ietta Street Atlanta, Oecrgia 30303 V
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Eear Mr. O'Reilly:
SEQUOYAH NUCLEAR PLANT UNIT 2 - ENVIRONMENTAL QUALIFICATION OF CLASS IE INSTRUMENIS IN THE VALVE ROOM - NCR'S SQN EEE 8003 AND SGN EEB 8004 -
REVISED FINAL REPORT The subject deficiency ms initially reported to NRC-0IE Inspector M. Thomas en April 7,1980, in acccedance with 10 CFR 50.55(e). Interim reports were submitted en May 7, July 7, September 12, and Octcber 13, 1980. A final repcrt was submitted en December 10, 1980. Enclosed is our revised final report.
The final report has been revised to delete an erroneous statement in the Safety Implications for SCN EED 8004 item 6.
This revision was reported to M. Thumas.
If you have any questiens, please get in touch with D. L. Lambert at FTS 857-2581.
Very truly yours, TENNESSEE VA' LEY AUTHORITY L. M. Mills, Manager Nuclear Regulation and Safety Enclosure Mr. Victor Stello, Director (Enclosure)Y cc:
Office of Inspection and Enforcement U.S. Nuclear Regulatory Commission Washington, DC 20555 pol 1 Git 810Al "S T g
ENCLOSURE SEQUOYAli NUCLEAR PLANT UNIT 2 ENVIRONMENTAL QUALIFICATION OF CLASS IE INSTRUMENTS IN THE VALVE ROOM NCR NO. SQN EEB 8003 AND NCR 50. SQN EEB 8004 10 CFR 50.55(e)
REVISED FINAL REPORT Description of Deficiency Nonconforming condition SQN EEB 8003 concerns the steam generator pressure transmitters (Foxboro Model EllGM) which are located in the valve rooms at Sequoyah Nuclear Plant. According to the latest revision of the FSAR, the transmitters are not qualified for the worst case environment result-ing f rom a hign energy line break in the valve room.
The detrimental environmental aspect is the temperature. FSAR Table 3.11-2 indicates that a peak temperature of 296 F inside the valve room is possible, while the transmitters in question are qualified to only 130 F.
As a result of this ccndition, all other instrumentation inside the valve roc =s has been evaluated. Those instruments that are not qualified which might pose a safety concern are documented in NCR No. SQN EEB 8004.
These are:
1.
Main steam pressure transmitters (one per loop) 2.
Level solenoid valves which route control air to lavel control valves
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which regulate water from the turbine-driven auxiliary feedwater pump to steam generators 1 and 4 (total of two) 3.
Steam flow control valve to auxiliary feed pump turbine (total of four) and corresponding handswitches Steam generator =ain feedwater isolation valve (total of four) 4 and corresponding handswitches 5.
Pressure switches for flow to auxiliary feed pump turbine 6.
Pressure switches which detect an auxiliary feedwater pipe break (total of six) 7.
Cable types CPJ, CPJJ, and PJJ used in the valve rooms
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Safet/ Icolications S;"EE38003 These steam generator pressure transmitters are designated as post-accident monitoring (PAM) equipment. Because loss of PAM instrumentatien is detricental to the operator's ability to take appropriate action to mitigate an accidert, this conditien could have affected plant safety.
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SCNEE23000 TVA's evaluation of the equipment covered by this NCR is listed below.
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- 1. Transmitters PT-1-1C, -8C, -19C, and -26C.
PT-1-1C,
-8C, -19C, and -26C are used for auxiliary control of at spheric relief valves'en the :ain stea: headers.
These FT's are only lined up when centrol is in the auxiliary code and are not required to operate for the accident. Therefore, this condition could not have adversely affected plant safety,
- 2. Sciencid valves LSV-3-174 and -175.
LSV-3-174 and -175 are used for flow centrol to stea: generator (SG) No.1 and SG No. 4 through turbine-driven auxiliary feedwater (TDAFW) headers.
Failure of these solenoids wculd result in one of two =0 des. Either the associated valve would receive air er air would be blocked resulting in valve isolatien.
Isolation would be an acceptable failure. If air _is being received, the valve is =cdulating and causing a less desirable situation.
However, :anual centrol of AEW is available, and the valve can be isolated frc: the rain centrol r00=. Isolation to SG 1 and 4 is acceptable since at least TDAFW would be provided to intact SG's 2 and 3 3 & t. Moter-Operated Valves (MGV) - FCV 1-15, 16, 17, 18; FCV 3-33, 47, 87, 100. These Mov's were originally found to have inadequate dc6unentation to justify operation in the accident terperature environ =ent.
The vender has now analyzed the subject equipment for the. higher te:peratures and has confirmed, by letter, that the valves under postulated accident conditions will perfor: their intended function. Therefore, this condition could not have adversely affected plant safety.
l Handswitches:
MS-1-153, 163, 173, 183, HS3-333, 473, 873, 1003 These handswitches are used for testing purposes and are not required to cperate in the accident environ:ent. However, spurious signals caused by failure of these switches could cause the valves to go l
to an undesirable position which could affect plant safety.
- 5. PDIS-1-17 and 18.
j Case 1 - Failure of the PDIS is postulated to cause isolation of the associated FCV's for the auxiliary Teed pu p turbine.
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Ccnsider the high energy line break (HEL3) associated with SG No. 4 and a failure of Octor-driven auxiliary feedwater (MDAFW) pump 1A-A.
The result is a total
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less of AFW except for the MDAFW pump 13-3 feeding the faulted SG No. 4 and intac,t SG No. 3 This is unacceptable feedwater flow which could adversely affect plint safety, A si=ilar situation would exist with a faulted SG No.1 and failure of MDAFW pu p 13-3.
Case 2 - Failure of the PDIS is postulated to not cause isolatien of the associated FCV's for the auxiliary feed pump turbine.
PDIS-1-17 and -18 are not required to cperate since they are used caly to indicate and isolate breaks in the TDAFW pu p reo: cr high flow in the TDAFW pump line. Therefore, TDAFW would be available to all SG's.
Also, a failed er faulty indicatien frc: the PDIS wculd not cause the operator to take 1: proper acticn since it provides local indication only. This failure =0de could not have adversely affected plant safety.
- 6. PS-3-160A&3, 165A&3, 1403, and 1503 Case 1 - Failure of PS's is postulated to cause associated LC7's to cl'ose.
Ccnsider the high energy line break (HEL3) associated with SG No. 4 and a failure of noter-driven auxiliary feedwater (MDA?W) purp 1A-A.
The result is a total loss of AFW except fcr the MDAFW pu=p 13-3 feeding the faulted SG No. 4 and intact SG No. 3 This is unacceptable feedwater flow which could adversely affect plant safety. This is the sa:e result as described above in Case 1 of Ite: 5.
Case 2 - Failure of PS's is postulated to not cause asecciated LCV's to close. The faulted SG would receive TDAFW as well as the other SG's.
The operator can isolate flow to the faulted SG at 10 =inutes.
Therefore, ' this = ode is censidered acceptable.
- 7. Internal wiring' (cable types CPJ, CFJJ, and PJJ) to junction boxes 30 2, 3061, 3066, 3063, 3062,~3069, 2690, 2391, 2857, and 2353.
These cables were originally suspected to be not qualified for the accident envirennent. We have since
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determined, from review of vender infor:ation, that the CPJ 7.nd CPJJ cables are adequately qualified.
Cable type PJJ is not qualified to the expected envirencent.
Failure of this cable cculd cause the less of safety-relsYed equipmeht'shich could adversely affect plant safety.
Cerrective Action SO:!IIIS003 The steam generator pressure transmitters will be replaced with trans itters which have been qualified for operation in the expected envirennent.
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Ite: 3&4:
The handswitches will be removed from service during ner al operation so that failure will not affect operation of the valves.
l SO:II33004 Ite: 5: The differential pressure switches will be modified to upgrade the level of qualification to meet the calculated accident envirencent.
Ite: 6: Two of the pressure switches will be coved cut of the harsh envirencent. This will result in acceptable AFW flew for the postulated event.
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Ite: 7: The cables which are not qualified to the expected envarennent (type PJJ) will be replaced.
All ccrrective acticns will be completed before fuel load.
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