ML19308D322

RO-77-21:on 770225,main Steam Valve MSV-36 Opened at 990 Psig Following Reactor Trip.Mainsteam Valve Lifted Due to Setpoint Drift.Main Steam Valve Calibr to Correct Lift Setpoint

ML19308D322
Person / Time
Site:	Crystal River
Issue date:	03/14/1977
From:	Stewart W FLORIDA POWER CORP.
To:
Shared Package
ML19308D321	List: ML19308D320 ML19308D322
References
NUDOCS 8002270769
Download: ML19308D322 (2)

Text

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@l 7 89 MSV-36 Relief Valve lifted due to reasons that are unknown at this time as the balance l

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Supplementary Information

1. . Report No: 50-302/77-21 l

2. Facility: Crystal River Unit #3

! 3. Report Date: 14 March 1977

4. Occurrence Date: 25 February 1977 l! 5. Identification of occurrence:

i Main Steam Relief Valve MSV-36 lifted at a pressure of 990 psig. The required setpoint is 1050 peig i 1%. <

6. Conditions Prior to Occurrence:

On 25 February 1977, Crystal River Unit #3 experienced a Reactor trip, t and the Unit was returning to Mode 4 (Hot Shutdown). -

7. Description of Occurrence:

While enteri:2g Mode 4, following a Reactor trip, the Main Steam Relief Valve MSV-36 opened below the required setpoint. No other Main Steam j Relief Valves opened at this time. There was no safety significance, i as the Reactor was in a tripped condition at the time of the occurrence..

I The balance of the MSV's were operable and redundancy was maintained.

When the steam pressure decreased to a point below the MSV setpoint, the setpoint was checked and reset.

! 8. Designation of Apparent Cause of Occurrence:

, The cause of this occurrence ras determined to be a normal setpoint drift.

9. Analysis of Occurrence:

This was the first occurrence of this event involving a Main Steam Safety Valve. When plant conditions allowed, the valve was calibrated to the

proper setpoint.

10. Corrective Action:

Main Steam Ralief Valve MSV-36 was calibrated to the correct lift setpoint of 1050 psig i 1%.

I 11. Failure Data:

No previous events of this type have occurred.

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