ML20214P519
| ML20214P519 | |
| Person / Time | |
|---|---|
| Site: | Trojan File:Portland General Electric icon.png |
| Issue date: | 11/10/1986 |
| From: | Whithers B PORTLAND GENERAL ELECTRIC CO. |
| To: | Martin J NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION V) |
| References | |
| IEB-86-003, IEB-86-3, NUDOCS 8612040246 | |
| Download: ML20214P519 (3) | |
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' November 10, 1986 Trojan Nucioar Plant Docket 50-344 Licence NpF-1 Mr. John B. Martin Regional Administrator, Region V U.S. Nuclear Regulatory Comminolon 1450 Maria Lane, Sutto 210 Walnut Crook CA 94596-5368
Dear Mr. Martin:
o IE Complianco Bulletin No. 06-03:
Potential Failure of Multiplo ECCS Pumpo Due to Single Failure of Air-Operated Valvo in Minimum Flow Recirculation Lino IE Comp 11anco Bulletin No. 06-03 addressos a problem concerning the failuro of multiplo ECCS pumps due to a single failure of an air-operated valvo in the pump miniflow recirculation lino. A review of Trojan's ECCS doelgn has concluded that this Bulletin la indirectly applicable. Provided below in PCE's response to the actions required by the Bulletin.
The Trojan ECCS incorporatoo throo noto of injection pumps. Theno are the safety injection (SI) pumpo (modium head), the contrifugal charging pumps (CCPs) (high head), and the rooidual heat removal (RIIR) pumpo (low head).
The miniflow recirculation for SI pumpo in the Wootinghouso doelgn used at Trojan has one normally open valve from each of the two indopondent trains in oorica in the common dischargo lino to the Refueling Water Storage Tank (RWST). This oorios doelgn assures that contaminated water will not bo discharged to the RWST during the post-LOCA recirculation modo. A drawback to this doelgn in that the miniflow recirculation function can be defonted by an inadvertent 0612040246 061110
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Pcrtiswxt Gerierci mCortixvist Mr. John B. Martin November 10, 1986 Pago 2 valvo closure. Unlike the plants ider.tified in the Bulletin that have air-operated valves that fail in the closed position, Trojan's valves are motor-operated and fail as is.
It is important to note that the SI miniflow recirculation isolation valves are maintained in the open position with each control switch in the mid-position and an associated lockout switch in " lockout". The lockout condition maintains the valve switchgear racked in, but with power to the operator removed.
This provides control room indication of valvo position While at the same time preventing a signal from closing the valve.
If valvo closure is required, power is restored by manually moving the lockout switch from " lockout" to the " normal" position. The valves are then manually closed when their respectivo control switches are placed in the "closo" position. Valvo position, operability, and lockout are verified every 31 days per Technical Specification 4.5.2.
The lockout feature assures that the miniflow lino is open to prevent pump deadheading yet available fecm the control room for the switch from the injection to recirculation modo, if required.
In the event RCS pressure recovers above 1520 psig, the Emergency Operating Procedures provido operator guidance to secure the SI pumps.
The CCP miniflow recirculation also incorporates two motor-operated isolation valves in series. These valves are maintained in the open position with power available to their motor operators. With a shutoff pressure of 2670 pois, it is less likely to encounter Plant conditions in which deadhead.8.ng is a concern.
Emergency Operating Procedures provide operator guidance for closure and reopening of the valvo(s) based on RCS pressure. Unlike the SI miniflow recirculation CCP miniflow recircula-tion need not be isolated when transitioning to the post-LOCA recircula-tion mode because it returns to either the CCP suction or VCT, not the RWST.
In the event that the miniflow recirculation valve (s) must be closed during normal operation, Plant procedures require an operator be posted as watchstandor to monitor charging flow. With charging flow less than 60 spm or an additional CCP operating, the valves must be opened immediately.
The RHR pump miniflow recirculation design is different from the provi-ously described systems in that the flow is returned to its respective pump suction. The miniflow systems are completely separate for each RHR pump and are not susceptibio to the common failure identified in the Bulletin.
PortlandGeneralElechicCor ay w
i-Mr. John B. Martin November 10, 1986 Page 3 s
In conclusion, tho problem of multiple ECCS pump failures upon single failure of one valve in the miniflow line is not a concern at Trojan due to i
differences in design and operation. No correctivo measures are therefore needed.
Sincerely, l--
Bart D. Withers s
Vice President Nuclear c:
U.S. Nuclear Regulatory Commission Document Control Desk Mr. Lynn Frank, Director State of Oregon Department of Energy 2
Subscribed and irwsrn to before me this 10th day of November 1986.
NotaryPublicofOg/gon v.
My Commission Expires:
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