ML20012D886

LER 99-004-00:on 900219,trip Setpoint for Isolation of Liquid Radwaste Effluent Line on Low Dilution Flow Not Set Correctly.Caused by Inadequate Procedure.Procedure Revised temporarily.W/900319 Ltr

ML20012D886
Person / Time
Site:	Hatch
Issue date:	03/19/1990
From:	Hairston W, Tipps S GEORGIA POWER CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
HL-1016, LER-90-004, LER-90-4, NUDOCS 9003290049
Download: ML20012D886 (7)

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[ 000350D March 19, 1990 L U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, D.C. 20555 L

PLANT HATCH - UNIT 1 NRC DOCKET 50-321 OPERATING LICENSE DPR-57 LICENSEE EVENT REPORT INADE0VATE PROCEDVRE RESVLTS IN INCORRECT __LIOVID i

RADWASTE DILUTION FLOW MONITOR SETP0lf!I Gentlemen:

In accordance with the requirements of 10 CFR 50.73(a)(2)(i), Georgia Power Company is submitting the enclosed Licensee Event Report (LER) concerning a condition which existed that was prohibited by the plant Technical Specifications. This event occurred at Plant Hatch - Units 1 and 2.

Sincerely,

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4. G. Hairston, III JJP/ct

Enclosure:

LER 50-321/1990-004 c: (See next page.)  ;

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c Mr. H. C. Nix, General Manager - Nuclear Plant i L Mr.'J. D. Heidt, Manager Engineering and Licensing - Hatch >

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I U.S. Nuclear Reoulatory Commission.- Washinoton. D.C.

Mr. L. P.-Crocker, Licensing Project Manager - Hatch  ;

i E U. S. Nuclear Reaulatory Commission. Reaion II  !

Mr. S. D. Ebneter, Regional Administrator  !

Mr.-J..E. Monning, Senior Resident Inspector.- Hatch  ;

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8 ACILITY hAmet m DOCS,8 Y Nutett h (Il PAGE W PLANT HATCHe UNIT 1 0 ]s ] o 10 l 0 I 312 l 1 1loFI015 TTLt .4, INADEQUATE PROCEDURE RESULTS IN INCORRECT LIQUID RADWASTE DILUTION FLOW MONITOR SETPOINT tvtNT Daf t tSi Ltm NL9he$th ($1 htPC3T Daf t (71 OTHkh 9 ACILITitt SWVOLVED 181 MO%TM day vtAm vtAR se A6

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On 2/19/90 at approximately 1400 CST, Unit 1 was in the Cold Shutdown mode and Unit 2 was in the Run mode at an approximate power level of 2436 CMWT (approximately 100% of rated thermal power). At that time, non-licensed plant trip setpoint for the isolation of the liquid radwaste (personnel LRW, Ellsdetermined Code WD) effluent that the line on low dilution flow was not always set per the requirements of Unit 1 Technical Specifications section 3.14.1 and Unit 2 Technical Specifications section 3.3.6.9.

The LRW effluent line isolation valves were set to close if dilution flow decreased to approximately 10,000 gallons per minute (gpm); however, some Liquid Radwaste Discharge Permits required a minimum dilution flow of greater than the 10,000 gpm  ;

isolation setpoint. For these LRW discharges, proper dilution flow was established, but the automatic isolation trip setpoint was not set per Technical Specifications requirements. A review of a sample of LRW releases indicated it is highly unlikely any release limits were exceeded.

The cause of this event is an inadequate procedure. Procedure 64CH-RPT-004-05,

" Liquid Effluents: Reports," did not prohibit the issuance of Liquid Radwaste Discharge Permits with a required minimum dilution flow of more than 10,000 gpm or, alternately, did not require the automatic isolation setpoint to be raised prior to the issuance of the discharge permit.

Corrective actions for this event include temporarily revising procedure 64CH-RPT-004-05, issuing an Operating Order to the Radwaste Operators, and scheduling permanent procedure revisions.

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LICENSEE EVENT REPORT ILEZ) TEXT CONTINUATION uPaovtoom ao mo-noe

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PLANT HATCH. UNIT 1 o151010101 3 211 90 -

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General Electric - Boiling Water Reactor  ;

Energy Industry Identification System codes are identified in the text as (EIIS Code XX).

SUMMARY

OF EVENT On 2/19/90 at approximately 1400 CST, Unit 1 was in the Cold Shutdown mode and Vait 2 was in the Run mode at an approximate power level of 2436 CMWT (approximately 100%

of rated thermal power). At that time, non-licensed plant personnel determined that the trip setpoint for the isolation of the liquid radwaste (LRW, EIIS Code WD) l effluent line on low dilution flow wa> not always set per the requirements of Unit 1 '

l Technical Specifications section 3.14.1 and Unit 2 Technical Specifications section  :

3.3.6.9. The LRW effluent line isolation valves were set to close if dilution flow decreased to approximately 10,000 gallons per minute (gpm); however, some Liquid l Radwaste Discharge Permits required a minimum dilution flow of greater than the i

10,000 gpm isolation setpoint. For these LRW discharges, proper dilutien flow was l established, but the automai;ic isolation trip setpoint was not set per Technical Specifications requirements. A review of a sample of LRW releases indicated it is highly unlikely any release limits were exceeded.

l The cause of this event is an inadequate procedure. Procedure 64CH-RPT-004-0S, I

" Liquid Effluents: Reports," did not prohibit the issuance of Liquid Radwaste Discharge Permits with a required minimum dilution flow of more than 10,000 gpm or, alternately, did not require the automatic isolation setpoint to be raised prior to the issuance of the discharge permit.

Corrective actions for this event include temporarily revising procedure 64CH-RPT-004-05, issuing an Operating Order to the Radwaste Operators, and scheduling permanent procedure revisions.

DESCRIPTION OF EVENT On 2/19/90 at approximately 1400 CST, non-licensed plant personnel were investigating a preliminary site Safety Audit and Engineering Review (SAER) audit finding issued on 2/15/90. The preliminary audit finding stated the possibility existed that the low dilution flow isolation trip setpoint for Unit 1 and Unit 2 liquid radwaste (LRW) effluent releases is not always set to ensure the release will terminate if the predefined minimum dilution flow (i.e., the minimum flow listed on ,

the discharge permit) is not maintained. This isolation trip setpoint is required by Unit 1 Technical Specifications section 3.14.1 and Unit 2 Technical Specifications section 3.3.6.9.

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0b 0h DF 0h The low dilution flow isolation trip setpoint is set to isolate the LRW effluent discharge line if dilution flow falls below approximately 10,000 gallons per minute (gpm). Occasionally, however, the predefined minimum dilution flow, as given on the Liquid Radwaste Discharge Permit for each release, has been greater than 10,000 ppm. In such instances, the low dilution flow isolation trip setpoint was not raised to reflect the higher predefined minimum dilution flow. Consequently, the release would not terminate automatically if dilution flow fell below the higher predefined minimum.

On 2/19/90, plant personnel determined that LRW effluent releases had been made for which the predefined minimum dilution flow was greater than 10,000 gpm. As part of the investightion, over 600 Liquid Radwaste Discharge Permits were reviewed. This represents roughly nine percent of the releases made since 7/1/85 (the date when the Technical Specifications requirements to have automatic isolation capability on low dilution flow became effective). In this sample, 25 cases (eight on Unit 1 and 17 on Unit 2) were found where the Liquid Radwaste Discharge Permit required a minimum dilution flow greater than the low dilution flow isolation setpoint of 10,000 gpm.

For these 25 cases, the renuired minimum dilution flows ranged from 12,000 gpm to 20,000 gpm. In each case documentation existed to demonstrate that the proper dilution flow had been established initially, however, the low dilution flow isolation setpoint had not been set per the requirements of Unit 1 Technical Specifications section 3.14.1 and Unit 2 Technical Specifications section 3.3.6.9.

This was documented on a Deficiency Card as required by plant administrative procedures.

When notified on 2/15/90 that the low dilution flow isolation trip setpoint may not always be set correctly, plant Chemistry and Operations personnel took im'nediate actions to ensure no LRW effluent releases would be made for which the predefined minimum dilution flow was greater then the isolation trip setpoint of 10,000 gpm.

Procedure 64CH-RPT-004-0S was revised temporarily to prohibit the issuance of any Liquid Radwaste Discharge Permit with a required minimum dilution flow of greater than 10,000 gpm. As an additional barrier, Operating Order 00-02-0290-S was issued to the Radwaste Operators prohibiting them from making any releases for which the required minimum dilution flow was greater than 10,000 gpm.

CAUSE OF EVENT The cause of this event is an inadequate procedure. Procedure 64CH-RPT-004-0S did not prohibit the issuance of Liquid Radwaste Discharge Permits with a required minimum dilution flow of more than 10,000 gpm or, alternately, did not require the automatic isolation setpoint to be raised prior to the issuance of the discharge permit.

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0l 0l4 0,0 0;4 or 0l5 REPORTABILITY ANALYSIS AND SAFETY ASSESSIENT This report is required per 10 CFR 50.73(a)(2)(i) because a condition existed that was prohibited by the plant's Technical Specifications. Specifically, the low dilution flow isolation trip setpoint was not always set at its predefined value as required by Unit 1 Technical Specifications section 3.14.1 and Unit 2 Technical Specifications section 3.3.6.9.

The function of the LRW effluent discharge line flow instrumentation is to monitor dilution flow and generate an isolation signal to terminate the LRW release if dilution flow decreases below the trip setpoint. (The flow instrumentation monitors the combined flow of the waste tank being discharged and the dilution water. However, the tank discharge flow is always less than 1% of the dilution water flow; thus, discharge line flow is considered to be dilution flow.) Non-radioactive dilution water, from Turbine Building Service Water (Ells Code KG) and/or the Circulating Water System (EIIS Code SG) is mixed with the small amount (75 gpm or less) of discharge flow from the waste tank prior to the effluent being discharged to the environment (i.e., the Altamaha River). This serves to dilute sufficiently the LRW effluent to ensure the instantaneous discharge limits of Unit 1 Technical Specifications section 3.15.1.1 and Unit 2 Technical Specifications section 3.11.1.1 are not exceeded at the discharge point. The flow monitor generates a flow signal which is fed to a trip unit. If the dilution flow drops below the trip unit's trip setpoint, the trip unit generates an isolation signal and valves 1(2)G11-F184 and 1(2)Gil-F185, Low Level Waste Discharge to Canal, close, thereby terminating the LRW effluent release. The Unit 1 and Unit 2 trip units are set to generate an isolation signal at a flow of approximately 10,000 gpm.

In this event, several examples were found in which the predefined minimum dilution flow was higher than the low dilution flow isolation trip setpoint of approximately 10,000 gpm. Therefore, for those releases, dilution flow could have dropped below the required minimum without the discharge being terminated automatically. However, it is highly unlikely instantaneous discharge limits were exceeded during any of these releases. Dilution flow is verified to be at or above the predefined minime before the release begins and 10 minutes after the release begins. These two flow: are recorded on the dischargo permit. This ensures adequate dilution flow is present. As a matter of good practice, Radwaste Operators periodically verify adequate dilution flow during the release. If dilution flow drops below the required minimum, immediate action is taken to terminate the release. Finally, the calculations used to determine maximum discharge flow, minimum dilution flow, and radiation monitor isolation trip setpoint have a 100% conservatism factor built-in to ensure a large margin exists between what is released and the Technical Specifications release limits.

Based on the above analysis, it is concluded that this event had no adverse impact on the health and safety of the public. Because the power level of the two units would not have changed the nature of the event, it is concluded this event would not have been more severe under other operating conditions, u , , ,,.. .. . . . cm, i,. 4m. *m

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01 0 01 5 or 0 l5 itxt u -. o .e u.w., m, CORRECTIVE ACTIONS Procedure 64CH-RPT-004-OS was revised temporarily on 2/15/90 to prohibit the issuance of any Liquid Radwaste Discharge Permit with a required minimum dilution flow of greater than 10,000 gpm.

Operating Order 00-02-0290-S was issued to Radwaste Operators on 2/15/90 prohibiting them from making any releases for which the required minimum dilution flow is greater than 10,000 gpm.

Permanent changes to Procedure 64CH-RPT-004-0S and any applicable radwaste system operating procedures are scheduled to be complete by 5/1/90. In the course of the investigation of this event, plant Chemistry management personnel have been made aware of the ongoing necessity for attention to detail to ensure that proper precautions are taken to provide confidence that the LWR effluent line flow instrumentation is set in accordance with Technical Specifications requirements.

ADDITIONALINFORMATI0t{

No plant components other than the LRW effluent discharge line flow instrumentation for Unit 1 and Unit 2 were affected by this event.

l L A previous similar event in which LRW effluent monitoring instrumentation was not set per Technical Specifications requirements was reported in LER 50-321/1989-017, dated 12/22/89. In that event, the isolation setpoint for the LRW effluent discharge line radiation monitoring instrument was found to be less conservative than that required by the Technical Specifications. Corrective actions included installing updated efficiency factors into system software, reviewing a sample of past LRW discharge l permits, revising three procedures, and counseling personnel. These corrective actions I

would not have prevented the event described in this LER because the causes of the two I events were different, different procedures were involved in each event, different instrumentation was involved in each event, and the isolation logic for the involved instrumentation functioned dif ferently.

I eonw ana v.s.crm meanan u m

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