ML20003H260
| ML20003H260 | |
| Person / Time | |
|---|---|
| Site: | Sequoyah  |
| Issue date: | 04/28/1981 |
| 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, SQRD-50-328-81, NUDOCS 8105050440 | |
| Download: ML20003H260 (2) | |
Text
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400 Chestnut Street Tower II
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April 28, 1981 70is(.-d Q
SCRD-50-328/81-32 ca ;.1 i N... s i:.w=un@ # LM
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Mr. James. O'Reilly, Director b
Office of I ection and Enforcement
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U.S. Nuclear gulatory Commissica D'7,_
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Regica II - Sui 3100 OD' 101 Marietta S Atlanta, Georgia 3 03
Dear Mr. O'Reilly:
SEC00YAH I.~0 CLEAR PLANI UNIT 2 - COEAINMEV. I HDROGEN ANALYZERS -
SCF.D-50-328/81 FINAL REPORT The suoject deficiency was initially reported to NRC-0IE Inspector R. V. Celenjak en April 24, 1981, in accordance with 10 CFR 50.55(e) as NCR SGN NEB 8123 Ecclosed is our final repcet.
If you have any questicos, please get in touch with D. L. Lambert at FTS 857-2581.
Very truly yours, TENNESSEE 7 ALLEY AUTHORITY L. M.' Mills, Manager Nuclear Regulatico and Safety Enclosure j
cc:
Mr. Victor Stello, Directcr (Enclosure)V Office of Inspectica and Enforcement U.S. Nuclear Regulatory Commissicn
'4ashington, DC 20555 30/'l s
/ I 8105050 W
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e ENCLOSURE SEGUOYAH NUCLEAR PLANT UNIT 2 CONTAINMENT HYDROGEN ANALYZERS SQRD-50-328/81-32 10 CFR 50.55(e)
FINAL REPORT
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Description of Deficiency The containment hydrogen analyzers monitor hydrogen concentration in the contain=ent. They require a constant calibrated amount of reagent gas (air) flow in order to accurately analyze the containment atmosphere. For Sequcyah, this reagent gas is supplied by the control air system. Due to the variable control air system load and since there are no provisions for reagent gas supply pressure regulation, control air pressure varies, resulting in variation of reagent gas flow and inaccuracy of calibration.
Currently, the only method of analyzer flow correction requires employees to enter the annulus and adjust the analyzer flow meter. This situation is unacceptable since the analyzers are required by NRC Regulatory Guide 1.7 to operate properly and reliably following a loss of coolant accident (LOCA), at which time the annulus is inaccessible to employees. Therefore, accurate adjustment of the analyzer flow would be impossible.
During weekly system functional tests, in which the analyzer calibration is checked, the readings were found to vary significantly between tests. This pro =pted a design change request (DCR) requesting installation of a pressure regulator on the reagent supply line. A review of this DCR resulted in the nonconfermance report.
Safety Implications If the deficiency had remained uncorrected, loss of continuous hydrogen analysis capability (post-LOCA) would result. The complete loss of function of the analyzer could have jeopardized the safe shutdown of the plant following a LOCA.
Corrective Action DCR 959 has been issued to correct the deficiency by having a pressure regulater installed en the reagent gas supply line. This action should permit proper analyzer calibration for the life of the plant. However, until the DCR is implemented, the procedure summarized below will be utilized to estimate the hydrogen concentratior. in the contaiment in the event of a LOCA. The following procedure will be incorporated into the emergency operating instruction before May 12, 1981.
The analyzer calibration must be checked before use and periodically thereafter by comparing the analyzer reading obtained from sample bottles with fixed concentrations of 1%,
4%, and 8% hydrogen, with the analyzer reading obtained from the containment atmosphere. Thereby, an upper limit of the actual containment hydrogen concentration can be determined.