ML20085C910

AO 50-254/74-27:on 740907,reactor Bldg Vent Stack I-131 Activity Exceeded Tech Spec Limit.Caused by Various Minor Steam Leaks Existing in Sys within Bldg.Minor Leaks Repaired as Identified or During Future Outages

ML20085C910
Person / Time
Site:	Quad Cities
Issue date:	09/17/1974
From:	Kalivianakis N COMMONWEALTH EDISON CO.
To:	Oleary J US ATOMIC ENERGY COMMISSION (AEC)
Shared Package
ML20085C912	List: ML20085C910 ML20085C915 ML20085C919
References
AO-50-254-74-27, NJK-74-284, NUDOCS 8307130200
Download: ML20085C910 (3)

Text

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~ Combwrith Edison &

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September 17, 1974

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' 'g, Mr. John F. O' Leary, Director Directorate of Licensing Regulation U. S. Atomic Energy Commission  !

Washington, D.C. 20545

Reference:

Quad-Cities Nuclear Power Station Docket No. 50-254, DPR-29 Appendix A, Sections .l.0. A.2, 3.8.B.3.a, and 6.6.B.l.a

Dear Mr. O' Le ary :

Enclosed please find Abnormal occurrence Report No. A0-50-254/

74-27 for Quad-Cities Nuclear Power Station. This was previously reported to Region III, Directorate of Regulatory Operationc by telephone on September 8,1974 and to you and Region III, Directorate of Regulatory Operations by telecopy on September 9, 1974.

This report is submitted to you in accordance with the require-ments of Technical Specification 6.6.B.1.a.

,Very truly yours ,

COMMONWEALTfl EDISON COMPANY QUAD-CITIES NUCLEAR POWER STATION

/b . 1 5h N. J. Kalivianakis Station Superintendent NJK/FRL/lk cc: Region III, Directorate of Regulatory Op'erations

,J. S. Abel '

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REPORT NUMBER: A0-50-254/74-27 .

REPORT DATE: Septe'mber 17, 1974 xx5 OCCURRENCE DATE: September 7,1974 FACILITY: Quad-Cities Nuclear Power Station Cordova, Illinois 61242

_ IDENTIFICATION OF OCCURRENCE: i Reactor building vent' stack I-131 activity greater than its limit.

CONDITIONS PRIOR TO OCCURRENCE:

Unit 1 In run mode at approximately 700 MWe s Unit 2 ' In run mode 1following startup and increasing power at 50 MWe/ hour DESCRIPTION OF OCCURRENCE: x;

_ On September 7,1974, Unit 1 was operg. ting at approxi-mately 700 MNe; Unit 2 was increasing' load at 50 MWe/ hour fol-

, lowing a startup after a mainfenance outage. The Unit 1 vent

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sy, stem had~ bee'n'in -normal operation for the entire day; the Unit 2 vent system had been off while inerting the Unit 2 dry-

+ well through the SBGT system. The Unit 1 drywell had been vented .at approximately 5:30 p.m. based on a sample taken at 3:30 p;m.. The ' sample results at that time showed the I-131 activity to be within limits. At 3:45 p.m. the Unit 2 vent system was returned to normal operation upon completion of the Unit 2 drywell inerting. At 11:15 p.m..the Unit 1 vent system was tripped while reducing load to perform MSIV testing. Also at that time, the vent syatem Halogen and Particulate filters were changed as part of the daily routine sampling. Subsequent analysis of these filters indicated that the daily discharge for I-131 had been 197.6% of Technical Specification 3.8.B.3.a for September 7, 1974. s Subsequent investigations revealed that the ~ Unit 1 I-131 activity had increased by a factor of 10 from the previous day.

Investigations in the plant located several minor steam leaks that were considered to be the source for the increased activity.

Additionally, the Unit 2 activity was higher than normal due to minor steam leaks ' associated with the unit startup.

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n- O DESIGNATION OF APPARENT CAUSE OF OCCURRENCE:

Component Failure The apparent cause of this occurrence is designated as component failures. The cause of the I-131 activity being high was due to various minor steam leaks existing on systems within the reactor building.

ANALYSIS OF OCCURRENCE:

The impilcations of this occurrence on the health and safety of the public are considered to be minimal due to the relatively short duration of the release in excess of the limit, and due to the conservative basis for this limit.

CORRECTIVE ACTION:

The corrective action taken to correct this occurrence was to isolate the reactor building vent systems and to operate the SBGT system. This was accomplished at approximately 4:00 a.m. on September 8,1974 following the analysis of the previous day's samples. Following this occurrence, the reactor building vent systems were run for only several hours each day to reduce the inventory of I-131. After approximately 5 days , the I-131 inventory was reduced to what are considered equilibrium levels.

A planned outage for Unit 2 began on September 12, 1974 During this outage, action was taken to repair various identified minor steam leaks that were contributing to the higher than normal I-131 activity.

Minor steam leaks are repaired as they are identified or during future outages. It is presently planned to repair minor leaks associated with Unit 1 on a planned outage in the near future. The reactor building vent systens will continue to be operated alternately with the SBGT system as is necessary to maintain the I-131 activity within limits.

FAILURE DATA:

l There is no specific failure data related to this occur-rence since the occurrence was caused by minor steam leaks from various1 systems. These minor leaks routinely occur and are i repaired as they _are identified.

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