ML20128B542
| ML20128B542 | |
| Person / Time | |
|---|---|
| Site: | Byron  |
| Issue date: | 05/07/1985 |
| From: | Querio R COMMONWEALTH EDISON CO. |
| To: | James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| References | |
| BYRON-85-0697, BYRON-85-697, NUDOCS 8505240571 | |
| Download: ML20128B542 (5) | |
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May 7, 1985 t.TR :
BYRON 85-0697 Mr. James G.Neppler Regional Administrator Region III U.S. Nuclear Regulatory Commission 499 Roosevelt Road Glen Ellyn, Illinois 61057 SUSJECT:
Byron Station - Unit One Special Reports on Emergency Core Cooling Actuations
REFERENCE:
- 1) Byron Station Technical Specification 3.5.2.
The attached reports are submitted in accordance with the requirements of Technical Specification 3.5.2 which requires a special report within 90 days of an Emergency Core Cooling System actuation.
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f8uW R. E. Querto Station Superintendent Byron Nuclear Power Station RtQ/CD/lh (0/32M) cc:
J. Hirnis - Resident Inspector E, %2r2 INPO Fotord Center V. I. Schlosser D. P. Calle ONI "Md l J4 h
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.(o BYRON UNIT 1 ECCS ACTUATION SPECIAL REPORT MAY 7, 1985 Attached is Licensee Event Report No. 45-020-00 which describes a Spurious Safety Injection Actuation on February 15, 1985. The Safety Injection i
resulted when the required 2 out of 4 logic for lort Pressuriser pressure was made up. At the time of the event, one Pressuriser pressure channel was out of service for calibration. A redundant channel tripped leading to the Safety Injection. This channel quickly reset in less than a second. The root cause of this event was indeterminate; however, it was believed that a radio was accidentally keyed by an operator near the transmitter causing a disturbance to the true signal.
This actuation was the second Safety Injection cycle encountered at Byron, Unit 1.
The first cycle, which injected flow through the high head injection flowpath on January 29, 1985 was non-reportable as it was preplanned in a pipe vibration Start-up test.
Address any questions to Erich Nurs at 815-234-5441, ext. 2250.
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i At 1733 hours0.0201 days <br />0.481 hours <br />0.00287 weeks <br />6.594065e-4 months <br />, an automatic Safety Injection actuation occurred. This resulted when one Pressurizer pressure channel was under maintenance and a second pressure channel tripped spuriously, making up the required 2 out of 4 logic for automatic l
01 actuation.
Because it is believed that a radio within the containment may have accidentally keyed and caused a disturbance to the pressure channel, radios will no longer tw allowed within the containment to eliminate any further possibility of radio-transaitter interference.
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I on February 15,1945, at 1733 hours0.0201 days <br />0.481 hours <br />0.00287 weeks <br />6.594065e-4 months <br /> with Unit 1 in Het stanty, an automatic f
safety injection actuation occurred. necording to the "First out Annunciator" alata, the safety injection was due to pressuriser low pressure. At the time of the event the Instrtment Maintenance Department had pressuriset pressure channel 4SS aut of service for calibration of the transmitter, 1pt-4SS. A redundant channot of Pressuriser preneure, channel 4S4, tripped, causing the spurious i
Safety injection by making up the required 2 out of 4 logic for automatic 31 actuation. That channel quickly reset in approstaately one-tenth of a second.
Also of note, the 440 channot for Pressuriser level spiked and reset within the same tlas framo.
The operator proceeded into the mergency procedure, "meactor Trip or safety i
Injection Unit l' and determined that the event was an inadvertent safety 3
Injection. The operator then entered the energency procedure 'st Termination Following spurious st" and returned the plant to normal.
1 The root cause of this event is indeterminate. Houever, the fact that both the j
pressure channel and level channel spiked and then quickly reset indicates some form of disturbance to their respective transmitters. At the time of the event, there vere twe operators near the trenemitters. For seergency comunicetton esamens, the oporatora did have a eadio with them, and it is possible thet the i
radio was accidentaty keyed leading to the transmitters' disturbance. These transmitters, manufactured by Barton, are known to be sensitive to radio transmisa hn. Other personnel were in the containment at the time, but were on j
the oppesite side of centalnment. They did not have eadlos. Aleo, the Load Dispatcher was contacted to check for grid perturbations but none were detected.
4 Free a safety 6tandpoint, the significance of this event is that the safety i
Injection System was performing its function properly. There was no danger leposed on the plant not the public as a result of this event.
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Although the cause of the event was not determined with certainty, corrective 4
action has been taken. All oporators have been informed that no radios are to be,
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carrled into the contalnment even for oneegency communicatton putposes. Also, l
j severat signs have been painted atound the contalnment airlock doors etressing to i
j everyone, that no radios are to be used within the containment. Ceesunication i
w111 he via the station's page syntes.
Forbidding radios within the containment i
will elleinste one possible form of tranneitter disturbance.
i previous occurrences none 1
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BYRON talIT 1 BCCS ACTUATION SPECIAL REPORT MAY 7, 1945 s
Attached is Licensee Event Report No. 85-023-00 which describes an automatic Safety Injection as a result of low steamline pressure on February 27, 1945.
The low steamline pressure was caused during the turbine speed control transfer from the throttle to the governor valves while in the manual mode.
After the transfer was thought to have been completed, the controller was placed in the auto mode and the governor valves promptly opened to about 50%
eausing high steam flow and low steamline pressure.
This event was the third Safety Injection cycle experienced at Syron, Unit 1.
Any questions should be directed to poter Knarr at $15-234-5441, ext. 234S or Erich Nuts at est. 2250.
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!.I,i, At 2217 hours0.0257 days <br />0.616 hours <br />0.00367 weeks <br />8.435685e-4 months <br /> an autoestic Safety Injection actuation occurred. This resulted when 2 out of 3 channels on 1 out of 4 steam 11nes indicated low steam 11ne pressure satisfying the St actuation logic. The event occurred while attempting to transfer turbine speed control tree the throttle to the governor valves in the manual mode. When the controller was returned to the auto mode after the transfer was believed to be completed. the governor valves opened abruptly to apptostaately 50%. The resulting high steam (tow produced the steastine pressure drop which in turn caused the 51 actuation.
Following this event, all throttle and governor valve position indications were recalibrated.
In additton, the governor valve position versus speed curve software for the Olgitsi tiectro-Hydraulle controller was revised.
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O 12 e = =..,,, n On l'ebruary 27. 1945, at 2217 hours0.0257 days <br />0.616 hours <br />0.00367 weeks <br />8.435685e-4 months <br /> with Unit 1 at approximately 6% power, an automatic Safety Injoctton occureed. This eesulted when 2 out o( 3 channels on 1 out of 4 steam 11nes indicated low steaaline pressure satisfying the SI actuation logic.
The events leading to this actuation are as follows:
Turbine speed was slowly being increased to the operating point of 1400 rpe.
Per procedure, at 1700 rpe, the throttle to governor valve transfer was initiated.
The teanstoe could not be coepteted in the Auto mode due ta problems with the computee soitwece. The Westinghouse Turb1ne eoptesentative and the Shitt conttol noce Engineer (Scat) insteucted the operator to place the control systee into turbine manual to complete the thrott1e to governor valve transfer. In manual, with the governor valves closed, the throttle valves were set to 40% open indicatlon. While attespting to eeturn to the euto mode the logic was such that the governor valves opened 50% creating a t'apid pressure drop in the steaaline.
This sudden pressure drop caused the St actuation. The actuation circuitry is rate sensitive, and the suddenness of the pressure drop increasci the magnitude of the pressure deviation signal input to the 51 actuation b1 stables, causing these to trip.
The toot cause of this event was taproper calibration of the Olgital Electro Hydraulic controller and the associated valve interlocks.
i The coreoctive action taken was eecalibcatton ot the positton indicattons and controls for the throttle and governor valves.
In addition, the governor valve versus speed curve software tot the Digital Electro-Hydraulle controller has been revised.
The goveenot valves were manufactuted by Westinghouse and the solenoids were manufactured by Moog.
This event had no safety significance since the plant responded as designed.
Safety Injection was actuated: this ensured that no danger was taposed on the plant or the public.
This event has not occurred tetore, O
1
BYRON UNIT 1 ECCS ACTUATION SPECIAL REPORT MAY 7. 1985 Attached is Licensee Event Report No. 45-035-00 which describes a Safety Injection as a result of low steamline pressure on March 14. 1945. The cause of this event was related to the plant conditions af ter performing the Loss of Offsite Power Start-up test. The steam generator atmospheric relief valves were opened to help control the reactor coolant pressure. This caused steam generator pressures to decrease. When the rate compensated portica of the pressure channels anticipated a steam generator pressure of 640 psig, the Safety Injection was actuated.
This was Dyron's fourth actuation cycle for Unit 1.
Questions should be addressed to Leo Wehner at 81.5-234-5441, ext. 2384 or Erich Wurs at ext. 2250.
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During plant recovery following a lett of Offille Power tett, a safety injection occurred due to low steamline pretture, fe prevent the recurrence of thlt event in the future, the operatort have been instructed on leproving control of plant parametert during a recovery of the primary and secondary lyttees from an abnormel operating tenditlen.
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Omron. Unit 1 0 l 5 1 0 1 0 1 0 l al 51 a 815 0l315 0 10 01 2 of 01 i ftXT Ouring plant recovery following a toss of Offlite Power telt on March 14,1905 asafetyinjectionoccurredat2153 hourt. The actuation signal was initiated by actual low Stem generator pretlure which esisted at the time, the plant was operating in Mode 3.
The cause of the event wel directly related to the operational condition of the plant at the time. The toss of Of f tlte Power telt had just been succettfully completed. The four Reactor Coolant Pwyl and the noral feedwater poet were not operating. The reactor trip caused an inmediate decreate in pretturlier orellure. At soon as power was rettered to the appropriate buttet via the diesel generators, the pretturlier heatert'were energlied to increate reactor coolant pretture. Af ter tis minutet, the pretturlier heaters were de-energized. Reactor coolant pretture continued to increate due to the latent heat contained in the pretturlier heatert. Ausillary feedwater flow had been initiated to the stem generatort Ismediately af ter the plant trip. To control the lacreating reactor coolant pressure, the stem generator atmospheric relief valves were opened and stem generator pressures decreated.
Pretturlier pretture responded by stabilising at approsimetely 2330 ping. The atmospheric relief valves were then closed. At this time, both the pretturlier and stem generator prettures continued to decreate. At 214f hourt the 10 reactor coolant pwp was started. At 2149 hours0.0249 days <br />0.597 hours <br />0.00355 weeks <br />8.176945e-4 months <br /> the IC reactor coolant pwp was started. This action caused an increate in reactor coolant pressure.
The atmospheric relief valvet were again utlllied to control the reactor coolant pretture. Thiscausedit'em generator pretture to decreate to approalmstely 640 pilg. The rate compensated portion of the stem generator pretture channels anticipated a stem generator pretture of 640 piltandthltinitiatedthetafetyinjectionand mein ste m llolation signalt. Subsequent events included the lif ting of the pretturnier power operated relief valvet and rettering of the prettwrlier Spray valves to control reactor coolant pretture. An orderly shutdown of the unit wat inillated after the plant stabillied, there were no tafety consequences or inplications at a result of thlt event, thetafetyinjectionautomatically Inillated at designed and all components alloclated with the tafety injection responded properly. The main steam llolation event it dittutted in report nweer 85 027 00, the most lignificant Contributing factor which precipitated this event was the lla minute period of tine in which the pretturlier heaters were energlied. To prevent recurrence of thlt event, the following items were covered with all of the station't licented operatort, s.
The lequence of events wat espleined in detall and an enphalls was placed on the need to progrell nothodically through an event.
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fhe operators were reminded of the latent heat phenwonen of the pretturlier heaters.
- c. A dil(ullion wel held Concerning the offetti of glarting an Idle featter Coolant pwp. The cold teal Injection water, which continuel to flow while the pep il idle, collectl in the crottover pipe. When the pwp ll llarted, thil pedet of Cold water il trantported to the Core and rapidly espandt al it it heated.
Ihll f autel a rapid increalt in reactor coolant pretlure which thould be espetted when ltarting a reactor toelant pep under these condillent.
Cile Safety Injectlent have occurred in the past, the particular plant condillent which were involved in thlt
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Cluation have not been esperienced before.
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BYRON UNIT 1 ECCS ACTUATION SPECIAL REPORT MAY 7, 1983 Attached is Licensee Event Report No. 85-034-00 which describes an accidental Manual Safety Injection Actuation on March 18, 1985. While performing a surveillance on Main Steam Isolation Valves stroke times, the Unit operator accidentally selected the Manual Safety Injection handswitch instead of the Manual Main Steam Isolation handswitch. Af ter the actuation, the operator quickly restored the plant to its original status - Cold Shutdown.
This actuation was the fifth Safety Injection cycle to date at Syron.
Address any questions to Erich Wurs at 815-234-5441, est. 2250.
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At 22$3. while performing the Main Steam Isolation Valves operability Test, the Unit operator accidentally actuated the Manual Safety Injection handswitch instead of the Manual Main Steam Isolation handswitch. The plant was in Cold Shutdown prior to the event and all safety systems responded as designed. The plant was promptly returned to its original condition within several minutes.
As a result of this event, all operators have been reminded via a Daily order i
Memo to double check any switch if their hands ever leave the switch prior to actuation.
Further. if the switch is related to Reactor Protection and/or Engineered Safeguard Features, and the actuation is non. emergency, then independent verification must be obtained before actuation.
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1985 at 2253 hours0.0261 days <br />0.626 hours <br />0.00373 weeks <br />8.572665e-4 months <br />, the Unit operator inadvertently initiated the Manual safety Injection instead of tne Manual Main Steam Isolation. The plant was in Cold shutdown at the time of the event.
The cause of this event was operator error. The operator was working with a Technical staff Engineer to record the stroke time of Main steam Isolation Valve 18e001C. One of the steps in the test requires the actuation of Nein steam Isolation by turning the appropriate handswitch on the Main Control Board. The Manual safety Injection handswitch is positioned on the immediate right of the Main Steam Isolation handewitch. The operator knew the correct handswitch to select but accidentally selected the Manual Safety Injection handswitch instead, hpparently, the operator was observing the engineer during the countdown to actuation and did not double check his hand placement prior to actuation.
Various alaras annunciated and all Safeguards equipment operated properly. The operator, cognizant of the problem. quickly returned the plant to its original condition within several minutes. The working atmosphere was normal, so no unusual characteristics were present to distract the operator.
From a safety standpoint, no danger was imposed on the plant nor the public because the plant was in Cold shutdown and all safety systems responded as espected.
For corrective action, a Daily Order Memo was sent from the Assistant J
tuperintendent operating to the Shift Er.gineers having them discuss with all operators what caused the event and how to avoid recurrence of the event. From this, the operators were told to read the label prior to operating any switch.
If their hand leaves the switch, they must re-verify that they are on the proper switch prior to actuating. Also, if the switch is related to Reactor Protection and/or Engineered safeguard Features actuation, and the actuation is non-emergency, then there must be independent verification prior to actuating.
previous occurrences None e
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