ML19308D437

RO-77-92:on 770717,steam Driven Emergency Pump EFP-2 Experienced Overspeed Trip on Autostart.Caused by Condensation in Steam Supply Preventing Fast Throttle Valve Closing.Drain Sys Modified & Steam Bypass Installed

ML19308D437
Person / Time
Site:	Crystal River
Issue date:	08/11/1977
From:	Stewart W FLORIDA POWER CORP.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
Shared Package
ML19308D420	List: ML19308D419 ML19308D437
References
NUDOCS 8002280751
Download: ML19308D437 (2)

Text

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• LCENSE NUMDER TYPE l0l0I-l0l0l0l0l0l-l0l0l L/l F l L l C l Rl P l 3 l 7 89 14 15 25 l264l 1l1l1l1l 30 l0l3l32 31 CATEcoRY rYpe SNN

• coCxET NUM0ER EVENT DATE REPORT oATE O 1 CON'T l - l - l 7 8 57 b6 59 W60 l0l5l0l-l0l3l0l2l G1 68 l Ol 7 l1l 7 l7 l7 l 69 74 l0 75 l8 l1 l1l7l7l 00 EVENT OESCRIPTION Oe l Following a unit trip, the Steam Driven Emergency Feedwater Pump (EFP-2) experienced an g 7 89 .

gg g l overspeed trip upon ah autostart. Redundant pump (motor-driven EFP-1) was started and g 7 89 UO g f, l utilized. This was a repetitive occurrence. The trip was reset immediately. The pudp 7 89 UO O5 l was re-started and 'run in the recirculation mode. (LER 77-92) l 7 U9 60 l

7 09 psuus 50 C E CODE COMPONENT CCCE M A A

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48 CAUSE DESCRIPTION *.*s 4 0o l Condensation in steam supply prevented throttle valve from closing fast enough to prevent l 7 89 ag l overspeed trip on initial start. The modified drain system plus a steam by-pass around the e' 7 89 R inlet valve that was completed on 5 August 1977 ,have demonstrated operability to this date.6 ST 3  % POWER oTHER STATUS otSCoVERY t1 78 9 y l0 l0 l0 l l_ NA l l Al l DISCOVERY CESCRIPTCN NA l 10 12 13 44 45 46 60 ACTMYY CodTENT DELEASto AMOUNT OF ACTMTV LoCATON of RELE SE

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80 PERSONNEL EXPOSURES NUMBER TYPE DESCR!PTCN i

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PERSONNEL INJuniES NUMGER oESC5b? TON

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80 l OFFSITE CONSEQUENCES

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g 7 80 80 LOSS OR DAMAGE TO FACIUTY TYPE CESCTEPTCN

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^ODITIONAL TACTO"3 l

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See attached Supolementarv Information 8002280 7 6[ j LU

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NAME: T. P . Seew1rt PHONE: (813) R66-4159

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., SUPPLEMENTARY INFORMATION port No.:

50-302/77-92 ,

2. Facili'ty: Crystal River Unit #3

3. Report Date: 11 August 1977

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4. Occurrence Date: 17 July 1977

5. Identification of Occurrence:

Failure of the Steam Driven Emergency Feedwater Pump (EFP-2) to autostart on mainsteam supply lineup contrary to Technical Specification 3.7.1.2(b) which requires two emergency feedwater pumps available and operable from two independent power sources.

6. Conditions Prior to Occurrence:

Mode 3 following a unit trip.

7. Description of Occurrence:

At 0407, following a unit trip, the main feedwater pumps were lost upon the transfer of '

buses. The Steam Driven Emergency Feedwater Pump (EFP-2) autostarted and tripped on /;

overspeed. The Motor Driven Emergency Feedwater Pump (EFP-1) was immediately started and the trip on EFP-2 was reset and the pump restarted. It has been demonstrated that EFP-2 will start on the second attempt. Short-term Instructions77-053 and 77-060 were issued to require daily testing of EFP-2 and requiring that an operator be stationed at the pump on a 24 hour-a-day basis, in order to operate EFP-2 if, and when, it is (n) required. A 15 minute steam line blowdown was accomplished every two hours and a reques

%,r for additional Engineering evaluation was submitted on 20 July 1977. Subsequently, EFP-2 experienced first stat: overspeed trips on 22, 23, 25 July, and 1 August 1977. Upon each occasion the trip was reset and EFP-2 was run either in the recirculation mode or opera-tionally tested by the operator stationed at the pump. Engineering evaluations were in progress during this time frame, and in addition to the previous modification to the drain system, a by-pass line around the steam inlet isolation valve ASV-5 was installed on 5 August 1977 to prevent condensate buildup. The Steam Driven Emergency Feedwater Pump has demonstrated operability to this date.

8. Designation of Apparent Cause:

The cause of this and subsequent events was determined to be condensation buildup in the steam inlet lines.

9. Analysis of Occurrence:

There is no safety hazard to the plant or public inasmuch as the redundant motor-driven Emergency Feedwater Pump has been available and operable, and EFP-2 has been in operable I

status, either running in the recire mode or manually.

10. Corrective Action:

To assure the prevention of condensation accumulation in the steam supply line upstream of the throttle valve, the drain system had been modified to tasure the drain capacity and a by-pass line was installed around ASV-5 to prevent condensate buildup.

O N.j 'ailure Data:

1 This occurrence is repetitive as reported by LER's 77-24, 77-37, and 77-56.

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