ML18036B063

LER 92-008-00: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: ML18036B061 ML18036B063
References
LER-92-008-02, LER-92-8-2, NUDOCS 9211170260
Download: ML18036B063 (10)

Text

NRC Form 366 U.S. NUCLEAR REGULATORY COWISSION Approved OMB No. 3150-0104 (6-89) Expires 4/30/92

,LICENSEE EVENT REPORT (LER)

FACILITY NAME (1) ]DOCKET NUMBER (2)

Br w r r n F TITLE (4) Drawing discrepancy caused isolation of the Unit 2 Off-gas Hydrogen Analyzers resulting in missed

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I I SEQUENTIAL I REVI SION I I I T

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I FACILITY NAMES V D IDOCKET NUMBER(S)

I 1 1 11 29 2 OPERATING I,ITHIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR 5:

MODE I I r f w I20.402(b) [20.405(c) ] ]50.73(a)(2)(iv) I73 71(b)

POWER I (20.405(a)(l)(i) [50.36(c)( 1) f )50.73(a)(2)(v) l73 71(c)

'LEVEL (20.405(a)( 1)(ii) (50.36(c)(2) f )50.73(a)(2)(vii) [OTHER (Specify in (20.405(a)( 1)(iii ) ]~]50.73(a)(2)(i)(B)f [50.73(a)(2)(viii)(A) Abstract below and in (20.405(a)( 1)(iv) 150 73(a)(2)'(ii) I l50.73(a)(2)(viii)(B) Text, NRC Form 366A) 4 N N NAME i AREA CODE MPN TF R 0 T I I IREPORTABLE.I I I 1 I IREPORTABLEI AS YT T P 0 N N T R N I. I I I I I I I I I I I PP MNA P T 0 4 EXPECTED IM NTH AY Y A I I SUBMISSION I P T N ABSTRACT (Limit to 1400 spaces, i.e., approximately fifteen single-space typewritten lines) (16)

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 *DOCK 05000260 S PDR NRC Form 366(6-89)

II NRC Form 366A UPS. NUCLEAR REGULATORY COHHISSION Approved OHB No. 3150-,0104 (6-'89) Expires 4/30/92 LICENSEE EVENT REPORT (LER)

TEXT CONTINUATION FACILITY NAHE (1) lOOCKET NUHBER (2)

I I I I SEQUENTIAL I /REVISION) ) f ) )

Browns Ferry Unit 2 I I I I I TEXT (If more space is required, use additional NRC Form 366A's) (17)

I. 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.

II- 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 the limiting condition for operation (LCO) which required a inoperable.'owever, 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.

r t t t 't t t t t t None.

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)

Ck 0 NRC Form 366A U. S. NUCLEAR REGULATORY CONNISSION Approved ONB No. 3150-0104 (6-89) Expires 4/30/92 LICENSEE EVENT REPORT (LER)

TEXT CONTINUATION FACILITY NANE (1) IOOCKET NUNBER (2)

I I I ISEQUENTIAL I IREVISIONI I I I I Browns Ferry Unit 2 I I I I I TEXT (If more space is required, use additional NRC Form 366A's) (17)

D t t None.

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.

F. t t Operations personnel were dispatched to release the hold order and 'the system was returned .to normal.

G t t None.

III. 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. gggttmud::

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 NRC Form 366A U.S. NUCLEAR REGULATORY COMMISSION Approved OMB No. 3150-0104 (6-89) Expires 4/30/92 LICENSEE EVENT REPORT (LER)

TEXT CONTINUATION FACILITY NAME (1) IDOCKET NUMBER (2)

I I I I SEQUENTIAL I I REVI SION I I I I l Browns Ferry Unit 2 I

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M I I I TEXT (If more space is required, use additional NRC Form 366A's) (17)

A 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 personnel identified 'the cause of the isolation (hold order B'perations 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.

I tv t A Design Change Notice (DCN) was issued to revise the affected control air correct air supply .to the Unit 1 and Unit 2 types'RC flow diagrams to show the hydrogen analyzers. This DCN ensures that Operations personnel will have accurate flow diagrams to preclude another hydrogen analyzer event of this Form 366{6-89)

41 NRC Form 366A U.S. NUCLEAR REGULATORY COMMISSION Approved OMB No. 3150-0104 (6&9) 4 Expires 4/30/92 I.ICENSEE EVENT REPORT (LER)

TEXT CONTINUATION FACILITY NAME (1) IOOCKET NUMBER (2)

I ISE()UENTIAL / /REVISION/

Browns Ferry Uni t 2 I Y AR I I I I TEXT (If more space is required, use additiona1 NRC Form 366A's) (17)

VI. ADDITIONAL INFOm TION 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)

41. I ~