ML20235H149
| ML20235H149 | |
| Person / Time | |
|---|---|
| Site: | Nine Mile Point  |
| Issue date: | 12/12/1986 |
| From: | NIAGARA MOHAWK POWER CORP. |
| To: | Linville J NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I) |
| Shared Package | |
| ML20235G041 | List: |
| References | |
| FOIA-87-438 NUDOCS 8709300392 | |
| Download: ML20235H149 (5) | |
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December 12, 1986 TO:
nville, Chief, Section 2C, DRP FROM: NMP Resident Office / Project Engineer WEEKLY STATUS REPORT #6 - NINE MILE POINT 2 1.
Plant Status:
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Although work was completed on MSIV actuator modifications, little schedule progress was made this past week due to the need for additional MSIV logic circuit modifications. The HSIV work remains the critical path for initial criticality. Preparations for reactor vessel hydrotest continued.
The inspection coverage was provided by the resident inspectors and was supplemented by Michelle Evans on MSIV work, post-fuel load preop testing, and surveillance testing.
Jim Linville reviews) site work during a three day site visit.
2.
MSIV Status:
Although the mechanical modifications to the actuators on the four inside MSIVs were completed this week, no net schedule progress was made due to the additional work added to the schedule to modify the MSIV logic circuits. The logic circuit modifications are discussed further below in the Followup on Previous Events section and are scheduled for completion on 12/12. Next, the MSIVs will undergo three days of preoperational testing, including stroke testing and additional leak testing.
An allegation was received this week concerning the hydraulic oil for the MSIVs. The alleger claimed that the addition of oil to the actuators has not been controlled, inadequate containers have been used, and no QC was involved. He claimed that he had taken oil samples from 2 actuators and found the oil to be dirty.
An allegation panel decided that the residents should promptly followup on this.
3.
Violation of Technical Specifications:
None.
4.
Reportable Events:
On 12/8 SBGTS train A auto started due to spiking on the Above Refuel Floor Ventilation Effluent Radiation Monitor. Air samples taken revealed only background radiation. The power supplied to the radiation monitor is being evaluated.
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On 12/10 the licensee reported a SBGTS design deficiency involving the he.aters, which protect the charcoal filters in both.
trains from moisture. During the performance of the monthly surveillance test, an operator noticed that the flow switch controlling the SBGTS heaters had tripped, deenergizing the heaters. The flow switch was designed to trip on low flow to protect the train from overheating due to insufficient system flow, sensed via the differential pressure between atmospheric pressure and the lower pressure inside the SBGTS train. After the SBGTS train started and established sufficient reactor building differential pressure. it went into a recirculation mode to maintain that pressure. Although the flow is the same in this mode, a slightly higher pressure in the train occurs, and the smaller differential pressure tripped the switch and turned off the heaters. To correct this design deficiency SBGTS will be modified to sense flow via the differential pressure across a filter bank inside the SBGTS train. The licensee is evaluating how the preop missed this deficiency.
On 12/10 and 12/11'three automatic High Pressure Core Spray (HPCS) initiations occurred. There were no injections as the injection valves were interlocked closed on high (actual) water level, as designed. The actuation signals resulted from the bumping of the variable leg instrument line on which two reactor vessel level transmitters are tapped. The instrument line has a flexible section adjacent to the primary containment penetration,
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and workers in this vicinity apparently bumped the flexible line.
Initial evaluations pursued bumping at the instrument rack and surveillance testing on the same reference leg as possible causes, but the later initiations ruled these out.
It is suspected that air in the instrument line caused the bumping to result in the transmitter trips. The trips were shown to be repeatable due to the flexible line bumping.
The HPCS System responded normally to the first two initiations.
However, during the third initiation the HPCS pump motor tripped on overcurrent. Evaluations have not yet determined the problem.
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Also, during the third initiation an operator shut down the HPCS diesel generator via emergency stop button while the diesel initiation was still in.
The diesel generator operated as i
designed. The licensee needs to change the operating procedure to properly address this situation.
5.
Followup on Previous Events:
The licensee determined that the 12/3 scram was caused by loss of g
both Uninterruptible Power Supplies (UPS), which supply power to RPS Sensor Buses and MSIV logic circuits. Loss of both power I
supplies has been traced to the paralleling of the 3A and 3B l
power supplies out of phase, which occurred during energized logic wiring checks on the MSIV 7D trip circuit. The MSIV trip solenoids are capable of being energized by both power supplies.
A design inadequacy permitted the 3A and the 3B UPS to parallel momentarily during a power transfer when one UPS was not
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e' disconnected prior to connecting the other UPS. The paralleling caused power variations as one UPS tried to feed the other. This caused the 3B UPS to blow an-inverter supply fuse thus removing one RPS sensor bus and causing a half scram. The 3A UPS switched to the alternate power supply, however a failed regulator card caused-the output voltage to go high and triggered the tripping of downstream Electrical Protection Assemblies (EPAs), resulting in the loss of the second RPS sensor bus and a full scram. The licensee is installing modifications to the MSIV logic circuits to prevent any such paralleling of UPS.
6.
Planned Activities:
NMP-2 has scheduled completion of MSIV logic circuit modifications by 12/12 and completion of MSIV testing by 12/15.
The hydrostatic test of the vessel seals is scheduled for 12/17.
Based on the current schedule, NMP-2 projects ~a 12/30 initial criticality at the. earliest. We continue to believe this date overly optimistic and believe a criticality during the first week of January would be the earliest.
7.
Cumulative Summary of Significant Events 10/31 - License issued 11/2 - Fuel loading began 11/5 - IRM reactor trip followed by SDV level reactor trip (ENS) 11/6 - Vital area breached without compensatory meesures (ENS) 11/7 - Fuel loading with bypassed SRM (LCO violation) 11/8 - Inoperable RB exhaust rad monitor (LCO violation) 11/9 - Two APRM reactor trips due to faulty circuit card (ENS) 11/10 - Inoperable RB exhaust rad monitor (ENS) 11/15 - Fuel loading completed 11/17 - Imbedded conduits without fire seals (LCO violation) 11/20 - Half scram / ESF actuation due to loss of UPS (ENS) 11/23 - Group 2 scram due to loss of power and APRM testing (FNS) 11/24 - Fire patrol errors found from 11/12 (LCO violation) 11/24 - CRD functional, friction, and scram testing completed 11/25 - SBGTS auto start due to detached jumper (ENS) 11/27 - SBGTS auto start due to rad monitor spike (ENS)
I 11/28 - SBGTS auto starts (2) due to RB ventilation trips (ENS) 11/30 - Completed installation of MSIV balls and leak tt:sts 12/3 - Scram due to loss of UPS power on MSIV logic flaw (ENS) 12/3 - Group 2 scram due to improper electrical isolation (ENS) 1 12/8 - SBGTS auto start due to rad monitor spike (ENS) l
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12/10 - SBGTS design deficiency on heater flow switch (ENS) l 12/10 - HPCS starts (3) due to instrument line bumping (ENS) l 4
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