05000260/LER-1992-008-02, :on 921012,drawing Discrepancy Caused Isolation of Unit 2 off-gas Hydrogen Analyzers Which Resulted in Missed Compensatory Sample Required by Ts.Design Change Notice Issued to Revise Affected Control Air Flow Diagram

:on 921012,drawing Discrepancy Caused Isolation of Unit 2 off-gas Hydrogen Analyzers Which Resulted in Missed Compensatory Sample Required by Ts.Design Change Notice Issued to Revise Affected Control Air Flow Diagram

ML18036B063
Person / Time
Site:	Browns Ferry
Issue date:	11/12/1992
From:	Jay Wallace TENNESSEE VALLEY AUTHORITY
To:
Shared Package
ML18036B062	List: 05000260/LER-1992-008, Forwards LER 92-008,providing Details Re Operation or Condition Prohibited by Ts.Drawing Discrepancy Caused Isolation of Control Air Supply to Unit 2 off-gas Hydrogen Analyzers & Rendered Analyzers Inoperable 05000260/LER-1992-008-02, :on 921012,drawing Discrepancy Caused Isolation of Unit 2 off-gas Hydrogen Analyzers Which Resulted in Missed Compensatory Sample Required by Ts.Design Change Notice Issued to Revise Affected Control Air Flow Diagram
References
LER-92-008-02, LER-92-8-2, NUDOCS 9211170260
Download: ML18036B063 (10)

LER-1992-008, on 921012,drawing Discrepancy Caused Isolation of Unit 2 off-gas Hydrogen Analyzers Which Resulted in Missed Compensatory Sample Required by Ts.Design Change Notice Issued to Revise Affected Control Air Flow Diagram

Event date:
Report date:
Reporting criterion:	10 CFR 50.73(a)(2)(iv), System Actuation 10 CFR 50.73(a)(2)(v), Loss of Safety Function 10 CFR 50.73(a)(2)(vii), Common Cause Inoperability 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications 10 CFR 50.73(a)(2)(viii)(A) 10 CFR 50.73(a)(2)(viii)(B)
2601992008R02 - NRC Website

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NRC Form 366 (6-89)

FACILITY NAME (1)

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F U.S.

NUCLEAR REGULATORY COWISSION

,LICENSEE EVENT REPORT (LER)

Approved OMB No. 3150-0104 Expires 4/30/92

]DOCKET NUMBER (2)

TITLE (4)

Drawing discrepancy caused isolation of the Unit 2 Off-gas Hydrogen Analyzers resulting in missed m

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" I,I' SEQUENTIAL I REVISION I I

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FACILITY NAMES IDOCKET NUMBER(S)

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OPERATING MODE POWER I

'LEVEL NAME [20.405(c)

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]50.73(a)(2)(iv)

[50.36(c)( 1) f

)50.73(a)(2)(v)

(50.36(c)(2) f

)50.73(a)(2)(vii)

]~]50.73(a)(2)(i)(B)f [50.73(a)(2)(viii)(A) 150 73(a)(2)'(ii)

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I20.402(b)

(20.405(a)(l)(i)

(20.405(a)( 1)(ii)

(20.405(a)( 1)(iii )

(20.405(a)( 1)(iv) 4 N

N I,ITHIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR 5:

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[OTHER (Specify in Abstract below and in Text,MPN TF R

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ABSTRACT (Limit to 1400 spaces, i.e., approximately fifteen single-space typewritten lines)

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On October 12, 1992, at 0908 hours0.0105 days <br />0.252 hours <br />0.0015 weeks <br />3.45494e-4 months <br />, the Unit 2 hydrogen analyzers for the Off-Gas System were declared inoperable due to the loss of control air to the sample panel.

This loss of control air to the Unit 2 hydrogen analyzers actually occurred at 0530 when Unit 1 Operations personnel implemented a hold order that closed valves on a Unit 1 control air supply header and inadvertently isolated the control air to the Unit 2 hydrogen analyzers.

Consequently, the required compensatory off-gas sample was not taken within the technical specifications (TS) timeframe.

The missed compensatory off-gas hydrogen sample requires a 30-day report in accordance with 10 CFR 50.73(a)(2)(i)(B) as an operation or condition prohibited by TS.

The root cause for the isolation of control air to the Unit 2 hydrogen analyzer was a drawing discrepancy in the control air system.

Specifically, the drawing did not show that the Unit 1 off-gas hydrogen analyzer control air also supplies the Unit 2

- off-gas hydrogen analyzer.

A Design Change Notice was issued to revise the affected control air flow diagrams to show the correct air flow configuration of the Unit 1 and Unit 2 hydrogen and oxygen analyzers.

Operations personnel identified the cause of the isolation and the hold order was released and the system was returned to normal.

A Caution Order was initiated and caution tags were placed on the affected valves.

9211170260 921112 PDR

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PDR NRC Form 366(6-89)

II(6-'89)

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NUCLEAR REGULATORY COHHISSION LICENSEE EVENT REPORT (LER)

TEXT CONTINUATION Approved OHB No. 3150-,0104 Expires 4/30/92 FACILITY NAHE (1)

Browns Ferry Unit 2 lOOCKET NUHBER (2)

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PLANT CONDITIONS

Unit 2 was at approximately 95 percent 'power and coasting down.

Units 1 and 3-were shutdown and defueled the Unit 2 off-gas system was in operation.

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DESCRIPTION OF EVENT

A. ~t:

On October 12, 1992, at 0530 hours0.00613 days <br />0.147 hours <br />8.763227e-4 weeks <br />2.01665e-4 months <br />, Unit 1 Operations personnel implemented a hold order to allow repair of a Unit 1 control air leak.

This hold order closed valves on the Unit 1 control.air supply header for the Unit 1 off-gas hydrogen analyzer which also inadvertently isolated the control air to the Unit 2 off-gas hydrogen analyzers.

As a result of the loss of control air [LF], the Unit 2 off-gas hydrogen analyzers [MON] for the off-gas System.[WF] were declared inoperable.'owever, the limiting condition for operation (LCO) which required a

4-hour compensatory off-gas sample to be taken was not entered until 0908 hours0.0105 days <br />0.252 hours <br />0.0015 weeks <br />3.45494e-4 months <br />.

The required compensatory off-gas hydrogen sample was not taken within the four-hour timeframe required by technical specifications(TS).

The 'missed compensatory off-gas hydrogen sample requires a 30-'ay report in accordance with 10 CFR 50.73(a)(2)(i)(B) as an operation or condition prohibited by TS.

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C October 12 at 0530 CDST Operations personnel implemented a hold order so that an air leak on Unit 1 could be repaired.

October 12 at 0908 CDST Hydrogen analyzers were declared inoperable.

Entered LCO for a 4-hour compensatory off-gas hydrogen sample.

October 12 at 1007 CDST Hold order was released and normal system alignment restored.

October 12 at 1040 CDST LCO was exited.

NRC Form 366(6-89)

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U. S.

NUCLEAR REGULATORY CONNISSION LICENSEE EVENT REPORT (LER)

TEXT CONTINUATION Approved ONB No. 3150-0104 Expires 4/30/92 FACILITY NANE (1)

Browns Ferry Unit 2 IOOCKET NUNBER (2)

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TEXT (If more space is required, use additional(17)

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E.

This event was known to the Control Room Unit Operator (utility, licensed) by 0908 when the no sample flow indicating light for the hydrogen analyzer remained illuminated after the completion of a surve'illance test on Unit 2 off-gas hydrogen analyzers.

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Operations personnel were dispatched to release the hold order and 'the system was returned.to normal.

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CAUSE OF THE EVENT

The immediate cause for the event was the inadvertent isolation of control air from the Unit 2 hydrogen analyzer panel when Unit 1 Operations personnel closed the control air header valves for the Unit 1 off-gas hydrogen analyzers on hold order 1-92-0195.

B.

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The root cause for the isolation of control air to the Unit 2 off-gas hydrogen analyzer was a drawing discrepancy.

Specifically, the drawing did not show that the control air supply to the Unit 1 hydrogen analyzers also supplies the Unit 2 off-gas hydrogen analyzers.

Therefore, when Operations personnel isolated the Unit 1 control air for the Unit 1 hydrogen analyzers, they inadvertently isolated the Unit 2 off-gas hydrogen analyzers.

NRC Form 366(6-89)

0(6-89)

U.S.

NUCLEAR REGULATORY COMMISSION LICENSEE EVENT REPORT (LER)

TEXT CONTINUATION Approved OMB No. 3150-0104 Expires 4/30/92 FACILITY NAME (1)

Browns Ferry Unit 2 IDOCKET NUMBER (2)

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TEXT (If more space is required, use additionalA contributing factor to this event was that Unit 2 was experiencing some water in the off-gas hydrogen analyzers sample lines.

This condition resulted in a blinking no sample flow light.

At 0530 hours0.00613 days <br />0.147 hours <br />8.763227e-4 weeks <br />2.01665e-4 months <br /> the no sample flow light stopped blinking and remained lit, and the Unit 2 control room Operations personnel believed that the light was a result of water in the Unit 2 off-gas hydrogen analyzers sample lines.'he corrective action for this -condition is to perform a surveillance test and enter the LCO, if necessary, based upon the results of on functional test.

However, as discussed previously, the valves, isolating the sample flow lines had been closed as a result of'a drawing discrepancy.

IV ANAITSIS OF THE EVENT The purpose of the off-gas hydrogen analyzers is to continuously monitor the off-gas process to ensure hydrogen concentrations are maintained below the potentially explosive gas concentrations due to the possibility of equipment damage and resultant adverse consequences.

Since the off-gas hydrogen recombiners continued to function properly, the actual hydrogen concentration was not affected.

Therefore, this event had no safety significance.

V.

CORRECTIVE ACTIONS

B'perations personnel identified 'the cause of the isolation (hold order 1-92-0915).

The hold order was released and the system-was returned to normal.

A caution order was initiated and caution tags were placed. on the valves.

The caution tags required an approval from the Shift Operations Supervisor (utility, licensed) to close these valves.

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A Design Change Notice (DCN) was issued to revise the affected control air flow diagrams to show the correct air supply.to the Unit 1 and Unit 2 hydrogen analyzers.

This DCN ensures that Operations personnel will have accurate flow diagrams to preclude another hydrogen analyzer event of this types'RC Form 366{6-89)

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U.S.

NUCLEAR REGULATORY COMMISSION 4

I.ICENSEE EVENT REPORT (LER)

TEXT CONTINUATION Approved OMB No. 3150-0104 Expires 4/30/92 FACILITY NAME (1)

Browns Ferry Unit 2 IOOCKET NUMBER (2)

I ISE()UENTIAL /

/REVISION/

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VI.

ADDITIONALINFOmTION A.

None.

B TVA reviewed previous reported events to find if similar past events had occurred and;,if so, why corrective actions had been unsuccessful in preventing this event.

One previous. event was identified (LER 296/88007).

This previous event involved the overheating of diesel generator 3C due to a loss of emergency equipment cooling water.

This event occurred because of the untimely implementation of a drawing correction which subsequently resulted in the misalignment of a cooling water inlet valve.

However, corrective actions of the LER 296/88007 event could not have prevented the October 12, 1992 event.

VII.

COMMITMENTS

None.

Energy Industry Identification System (EIIS) codes are identified in the text as [ZX].

NRC Form 366(6-B9)

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