ML20214U235
| ML20214U235 | |
| Person / Time | |
|---|---|
| Site: | Beaver Valley |
| Issue date: | 09/12/1986 |
| From: | Carey J DUQUESNE LIGHT CO. |
| To: | Murley T NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I) |
| References | |
| 2NRC-6-095, 86-11, NUDOCS 8609300547 | |
| Download: ML20214U235 (3) | |
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M 2NRC-6-095 Beaver Valley No. 2 Unit Project organization Telecopy 4 )
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$,G B Sept. 12, 1986 I ng Shippingport, PA 15077 United States Nuclear Regulatory Commission Region I 631 Park Avenue King of Prussia, PA 19406 ATTENTION: Dr. Thomas E. Murley Administrator
SUBJECT:
Beaver Valley Power Station - Unit No. 2 Docket No. 50-412 Priority Raise Feature of Steam Generator Stean Dump Valves Potential Significant Deficiency Report 86-11 Gentlemen:
This Potentially Reportable' Significant Deficiency Report is being submitted pursuant to the requirements of 10CFR50.55(e).
This is a final report.
No additional reports are anticipated.
DUQUESNE LIGHT COMPANY l
By
- 3. J. Carey Senior Vice President RWF/ijr NR/SDR/8611 Attachment cc:
Mr. P. Tam, Project Manager
- w/ attachment Mr. J. M. Taylor, Director (3)
- w/ attachment.
Mr. J. Beall, NRC Sr. Resident Inspector - w/ attachment Mr. L. Prividy, NRC Resident Inspector
- w/ attachment INP0 Records Center
- w/ attachment NRC Document Control Desk
- w/ attachment 8609300547 860912 PDR ADOCK 05000412 S
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Beaver Valley Power Station Unit 2 Duquesne Light Company Priority Raise Feature of Stean Generator Stean Dump Valves 1.
Summary During preliminary testing of the atmospheric stean dump valve con-trollers (2SVS*PCV 101 A, B, C), it was detennined that when the high pressure setpoint is exceeded, the controller will drive the valve full open and renain open even after the system pressure decreases below the setpoint.
2.
Immediate Action Taken Change Assessment Package No. 38 was issued-requesting the plant design for the stean generator Atmospheric Stean Dump Valves be changed to allow the valve to modulate closed when a high pressure setpoint is no longer exceeded.
On August 13, 1986, Mr. R. Wallauer called Mr. L. Tripp reporting this issue as a potential significnt deficiency.
3.
Description of Deficiency The stean generator hydraulically operated Atmospheric Stean Dump Valves (or PORVs) nonnally are used to control secondary pressure by manual control or by automatic valve modulation as a function of secondary pressure. The Atmospheric Stean Dump Valves (2SVS*PCV 101 A, B, C) controllers, when sensing a high stean pressure signal in the rack mounted 7300 pressure switch, will drive the valves full open (ranp) via a " priority raise" feature.
The priority raise feature overrides both the manual and modulating signals.
When the secondary pressure decreases below the setpoint, the priority raise override signal is removed.
However, the controller renains in the manual mode with 100% output (valve open) regardless of whether it was initially being operated in manual or automatic.
To close the v al ve, the operator must take manual action by using the manual
" output decrease" or by depressing the " automatic" pushbutton.
4.
Analysis of Safety Implications Any plant transient which exceeds the high stean generator pressure setpoint for the stean generator Atmospheric Stean Dump Valves will fully open all three valvcs.
This results in Main Stean Systen pressure decrease and plant cooldown fran all three stean gene-rators.
Without prompt operator intervention after the secondary pressure decreases below the priority raise feature setpoint, an (uncontrolled) stean blowdown could occur fran all three stean gene-rators which would exceed the safety analyses stean flow /stean line break bases.
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5.
Corrective Action Change Assessment Package. No. 38 was approved and the design for-the atmospheric stean dump controllers is being modified to reclose.,the valves when.stean pressure decreases or to renove the priority raise control. feature. With this design modification, the possibility for an uncontrolled stean' blowdown from all three stean generators due to a priority raise feature signal will be renoved.
This change will be implenented by initial fuel load for Beaver Valley Unit No.
2.
6.
Additional Reports This is a final report.
No additional reports are anticipated..
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