05000267/LER-1976-002, Suppl to LER 76-002A:on 760116,during Operation of Circulator W/Water Turbine Drives,Circulator Speed Reduced. Caused by Water Accumulation in Turbine Scroll Case. Investigation Continuing

Suppl to LER 76-002A:on 760116,during Operation of Circulator W/Water Turbine Drives,Circulator Speed Reduced. Caused by Water Accumulation in Turbine Scroll Case. Investigation Continuing

ML20085M289
Person / Time
Site:	Fort Saint Vrain
Issue date:	04/01/1976
From:	Franek W, Hillyard H, Swart F PUBLIC SERVICE CO. OF COLORADO
To:	Howard E NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV)
Shared Package
ML20085M291	List: 05000267/LER-1976-002, Suppl to LER 76-002A:on 760116,during Operation of Circulator W/Water Turbine Drives,Circulator Speed Reduced. Caused by Water Accumulation in Turbine Scroll Case. Investigation Continuing
References
LER-76-002A, LER-76-2A, P-76087, NUDOCS 8311080173
Download: ML20085M289 (6)

LER-2076-002, Suppl to LER 76-002A:on 760116,during Operation of Circulator W/Water Turbine Drives,Circulator Speed Reduced. Caused by Water Accumulation in Turbine Scroll Case. Investigation Continuing

Event date:
Report date:
2672076002R00 - NRC Website

text

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( '  %/ l REPORT DATE: Ap r'il 1 m1_9_J 6 ABNORMAL OCCURRENCE 76/02A SUPPLEMENT OCCURRENCE DATE: January 16, 1976 Page 1 of 4 FORT ST. VR\IN NUCLEAR GENERATING STATION PUBLIC SERVICE COMPANY OF COLORADO P. O. BOX 361 PLATTEVILLE, COLORADO 80651 REPORT NO. 50-267/76/02A Supplement IDENTIFICATION OF OCCURRENCE:

The reduction of circulator speed due to water accumulation in the steam turbine scroll case while operating the circulator with the water turbine has occurred on other circulators. This report is attached as a supplement to Abnormal Occurrence 50-267/76/02, dated January 26, 1976.

CONDITIONS PRIOR TJ[ OCCURRENCE: Steady State Power Routine Shutdown Hot Shutdown Routine Load Change X Cold Shutdown Other (specify)

Refueling Shutdosn Routine Startup The major plant parameters at the time of the event were as follows:

Power RTR 0 1Mth ELECT 0 NWe Secondary Coolant Pressure N/A (See Note 1) psig Temperature N/A (See Note 1) *F Flow N/A (See Note 1) #/hr.

Primary Coolant Pressure (See Note 2) psig Temperature (See Note 3) *F Corc Inlet (See Note 4) *F Core Outlet Flow (See Note 5) #/hr.

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p p d ABNORL.J OCCUllRENCE 76/02A SUPPLEMENT Page 2 of 4 NOTE 1: Incidents are independent of secondary coolant cond it ions .

NOTE 2: Incidents have occurred between 30 psig and 275 psig.

NOTE 3: Core temperature inlet has varied from 100*F to 166*F.

NOTE 4: Core temperature outlet has varied from 100*F to 166*F.

NOTE 5: Circulator speed has been from 1,100 rpm to 2,500 rpm and has occurred on one circulator when two are operating at 2,500 rpm.

DESCRIPTION OF OCCU RRENCE:

Primary coolant was being circulated by various combinations of circulators on Pelton drive including single circulators operating above self-turbining. In these instances the reactor operator noted a reduction la hulium circulator speed with no corresponding decrease in water flow to the Pelten drive.

There was no trip or alarm required or caused by this condition.

In all cases the circulators were returned to normal by opening the trap bypass valves on the inlet and outlet cold reheat piping.

APPARENT CAUSE OF OCCURRENCE: X Design Unusual Service Cond.

Including Environment Manufacture Component Failure Installation /Censt. Other (specify)

Operator Procedure ANALYSIS OF OCCURRENCE:

Incidents of the circulator speed reduction, due to water accumulation in the steam turbine scroll case, have occurred during normal operating conditions with either feedwater or condensate driving the Pelton wheels.

Reference attached helium circulator drawing. Bearing water flows down the circulator shaft and forms the lower water seal. This water then flows past the steam labyrinth and into the steam turbine scroll case, and the cold re-heat piping. The water in the cold reheat piping does not drain out of the piping traps. These traps are designed for steam operation and do not allow water flow equal to the water flow to the piping. Eventually the piping fills wit!. water and submerges the steam turbine. The submerged turbine increasea the circulator drag and reduces speed. When t he trap bypass valves are opened the water flows out of the piping and circulatar speed returns to normal.

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. Page 4 of 4 CORRECTIVE ACTION:

Abnormal Occurrence 50-267/76/02 stated a representative number of steam traps were checked and reported to be operating normally.

The problem of steam turbine flooding is being investigated. Test, T-22, has been approved to determine whether the steam traps are performing the desired function while operating the circulators on Pelton drive. Per agreement with Region IV, Inspection and Enforcement, no further incidents of steam turbine flooding will be reportad until the problem has been resolved.

FAILtiRE DATA /SIMILAR REPORTED OCCURRENCES:

None PROGRAMMATIC IMPACT,:

None CODE IMPACT:

None

/ f-Submitted by: ,/ /[/ p p II. k'. Sill a rd , r.

Technical Services Supervisor

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Reviewed by: TY^ <--  %,

11. Larry Brey \

Superintendent, Operatlons  ;

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[- w!wwtf Approved by: - 9 4 -

t z.o F/edericE. Swart Superintendent, Nuclear Production

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pubHe Service Company

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\ ., P. O. Box 361, Platteville, Colorado 80651

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April 1, 1976 Fort St. Vrain

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$, & P-76087 ll g .

Mr. E. Morris Howard, Director Nuclear Regulatory Commission .

Region IV Office of Inspection and Enforcement Suite 1000 Arlington, Texas 76012 REF: Facility Operating License No. DPR-34 Docket No. 50-267

Dear Mr. Howard:

Enclosed please find a copy of Abnormal Occurrence Report No. 50-267/

76/02A, Supplement, submitted per the requirements of the Technical Specifications.

Also, please find enclosed one copy of the Licensee Event Report for Abnormal Occurrence Report No. 50-267/76/02A.

Very truly yours, f h

l Frederic E. Swart E M' Superintendent, Nuclear Production

! Fort St. Vrain Nuclear l

Generating Station l FES/alk cc: Mr. Roger S. Boyd e

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