ML19261F316

RO 77-19/3L:on 770713,leak in Miscellaneous Waste Evaporator Feed Tank Immersion Heater Shorted Out Heater & Feed Pump. Caused by Matl Failure in Heater Temp Element.Heater Replaced & Operating Procedure Modified.Forwards LER

ML19261F316
Person / Time
Site:	Three Mile Island
Issue date:	08/12/1977
From:	Herbein J METROPOLITAN EDISON CO.
To:
Shared Package
ML19261F317	List: ML19261F316 ML19261F318
References
GQL-1100, NUDOCS 7910250777
Download: ML19261F316 (4)

Text

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u S. NUCLE AR REGULATORT MISSION COCKET NUM BE R NRC PoRu' 195 -

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TJRC DISTRIBUTION FeR PART 50 DOCKET MATERI AL INCIDENT REPORT FROM: oATE OF DOCUMENT l TO:

Metropolitan Edison Ccmpany

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8/12/77 Mr. BoyC H. Grier Reading, Pa. DATE RECEIVED J. G. lierbein 8/19/77 O N OTO R IZ E D PROP INPUT FORM NUMBER OF CCPIES RECEIVED l NETTER #

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• ENCLOSU R E Licensee Event Report (R0 50 289/77-19/3L) on 7/13/77 Concerning miscellaneous waste

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evaperator leakage showing abnormal degradatior

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PLANT NAME:

Three Mile Island Unit No. 1 RJL 8/19/77 (3-P) (1-P)

NOTE: IF PERSONNEL EXPOSURE IS INVOLVED SEND DIRECTLY TO KREGER/J. COLLINS

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. L~:,, na. -a s METROPOLITAN EDISON COMPANY sess ouav or mam m.m.corev ic, ccum POST OFFICE BOX 542 READING, PENNSYLVANI A 19603 TELEPHONE 215 - 929-34.01 August 12, 1977 GQL 1100 Regulatory File Cy, Mr. Boyce H. Grier, Director Office of Inspection and Enforcement, Eegicn I U. S. '!uclear Regulatory Ccrmission

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631 Park Avenue King of Prussia, PA 19406 rear Sir:

Docket No. 50-289 Cperating License No. DPR-50 In accordan :e with the Technical Specifications of our Three Mile Island Nuclear Sta; icn, Unit 1 (TMI-1), we are reporting the following reportable occurrence.

1) Report Number: 77-19/3L 2a) Required Report Date: 08/12/77 2b) Ca e of Occurrence: 07/13/77

3) Facility: "'hree Mile Island auclear Station, Unit 1.

h) Identification of Occurrence:

Title:

Miscellaneous Waste Evaporator leakage Shoved Abncrmal Degradation of a System.

Type: A reportable occurrence as defined by Technical Specification 6.9.2.3 (h) in that liquid leakage from the Miscellaneous Waste Evaporator, due to both the emersion heater and the steam tubes, showed abnormal degradation of a systam designed to contain radioactive material resulting from the fission process.

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August la 1977 Fr. Bo.yce H,. Grier GQL 1100

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5) Conditions Prior to Occurrence:

Power: Core 100%

Electric 807 MWe Gross RC Flev: lh0 x 100 lbs/hr RC Pressure: 2155 psig RC Temp: 579 F PRlR Level: 225 inches FRZR Temp: 6h9 F

6) Description of Occurrence:

On July 5,1977, a leak in the Miscellaneous Waste Evaporatcr feed tank emersion heater shorted out the heater and the feed pump. The heater was removed and replaced with a spara. An inspection of the original heater revealed that the leak occurred in a temperature prote that is standard equipment on the heater but is not used in TMI's applicaticn. After replacing the heater, the steam heating tube bundle of the evaporator was tested to determine if it leaked. The test was performed by removing the steam chest, that being the cover of the tube sheets, and visually inspecting for leaks fo31cving partial filling of the concentrater with water and pressurizing it with nitrcgen to 5 psig. Leaks were observed in approximately 50% of the steam tubes.

7) Apparent Catse of Occurrence:

It is believed that the cause of this occurrence was due to material failure in that the heater temperatur' element had failed due to pitting.

The pitting is believed to have been caused by heat., low pH and the pctential presence of chlcrides. The steam tube failure is believed to have been caused by corrosion of the tube =aterial. Since the tube bundle was act rencved, the exact mechanism of the railure is not kncvn, but vill be determined at a later date when the tube bundle is replaced.

8) Analysis of Occurrence:

The leekage through the heater element did not cause a threat to the health and safety of the public and did not affect the safe operation of the plant, in that the liquid that leaked frcs the feed tank drained to the floor drains and subseque.uly, to the Auxiliary Building sump. The sump contents are returned to the Liquid Waste Disposal System for processing.

The leakage through the steam tubes is prevented during operation of the evaporator because a pressure gradient is maintained between the non-ccntaminated steam (5 psig) and the concentrator (15-20 inches of mercury vacuum). This causes steam to flev from the tubes into the concentrator.

This has been confirmed by analysis of the condensate returned to the condenser during evaporator operation.

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Mr. Boyce H. Grier August 12, 1977

, GQL 1100

9) Corrective Action:

IMMEDIATE: Replaced the emersion heater with a spare. Mcdified the Mdscellaneous Waste Evaporator Operating Procedure to prevent the flew of radioactive liquid frem entering the steam tubes during evaporator shut devn, sample steam condensate during start-up of the evaporater, and dump steam to floor drains until sampling shows any contaminaticn found is within limits.

LCNG TERM: Inspect the emersion heater more frequently and replace as necessary based on the inspections. The steam tube bundle will be replaced with a bundle fabricated with material, such as titanium, Nicoloy 625, cr Nicenal 825, that is scre capable of withstanding the conditiens present in the evaporator.

The Plant Operations Review Cc=mittee and Unit Superintendent have reviewed and approved the above corrective action and have taken steps to assure its completien.

101 Failure Data:

(? ) Enersion Heater AIE-York Ray D, Pak Evaporator Riley Beaird Enersion Heater GKW h80V 3 phase Part. No. HTR 2L 89-117-1310-8 Material 30h SS (0.037 mils)

(2) Rav Water Heater (Steam Tubes)

A'E-York Ray D, Pak Evaporatcr

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U Tube Ccnstruction:

316 L Material 18 BW6 5/8 in diameter tube type Similar Events:

76-27/3L nee-el',

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Attachment:

LER cc: Ms. Margaret Reilly Chief Divisitn of Reactor Review

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PaDER Fulton Building Harrisburg, PA 17120