ML20005E513

LER 89-017-00:on 891128,discovered That Efficiency Factors Used for Old Liquid Radwaste Discharge Radiation Monitors Incorrect.Caused by Personnel Not Incorporating Updated Efficiency Factor Into Sys software.W/891222 Ltr

ML20005E513
Person / Time
Site:	Hatch
Issue date:	12/22/1989
From:	Hairston W, Tipps S GEORGIA POWER CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
HL-892, LER-89-017-00, LER-89-17, NUDOCS 9001080053
Download: ML20005E513 (7)

Text

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George Poen Company

', 333 Pedmont Amue O Atlanta. George 30308

. o- Telethone 404 $26 3195 Mekng At

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, 4D Inverten Contor Pa*way l l-- Post Offee Box 1295 ,

Dam 4ngham. Alatiama 35201  ;

Teesmone 205 068 55B1 j

!!c sounwvn viktre ugem e W. G. Hairston, all

. Senior Vee Prescent

• Nuclear otwrations  ;

HL-892 0501V December 22, 1989 U.S. ficclear Regulatory Commission

• ATTN: ? Document Control Desk Hashington, D.C. 20555 -

i PLANT HATCH - UNIT 1 NRC DOCKET 50-321 OPERATING LICENSE DPR-57 +

LICENSEE EVENT REPORT .

PERSONNEL ERROR RESULTS IN INCORRECT LIOUID R&DHASTE DISCHARGE MONITOR SETPOINT .

Gentlemen: 't 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 )lant Technical -Specifications. This event occurred at Plant Hatch - Unnts 1  ;

and 2. ,

Sincerely,  ;

's7 gy k.(b.d i "an-H. G. Hairston, III ,

SHR/ct

Enclosure:

LER 50-321/1989-017 ,

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o U.S. Nuclear Regulatory Commission December 22, 1989 Page Two c: Georaia PQn r Company Mr. H. C. Nix, General Manager - Nuclear Plant Mr. 3. D. Heiot, Manager Engineering and Licensing - Hatch GO-NORMS  !

U.S. Nuclear Regulatory Commission. Washington. D.C. t Mr. L. P. Crocker, Licensing Project Manager - Hatch U.S. Nuclear Regulatory Commission. Region II Mr. S. D. Ebneter, Regional Administrator Mr. J. E. Henning, Senior Resident Inspector - Hatch t

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On 11/28/89 at approximately 1600 CST, Unit 1 was in the Run mode at an approximate power level of 2436 MWt (approximately 100 percent of rated thermal power) and Unit 2 was in cold shutdown at an approximate power level of 0 MWt. At that time, plant chemistry personnel, while determining efficiency factors for newly installed liquid radwaste (LRW) discharge radiation monitors (Ells Code MON), found that the efficiency factors which had been used for the old monitors were incorrect. This discrepancy was found to apply to both units and resulted in the isolation setpoint )

of the LRW discharge monitoring instrumentation, which is a backup to isotopic analysis of the discharge tank, being less conservative than is required by Unit 1 Technical Specifications section 3.14.1 and Unit 2 Technical Specifications section 3.3.6.9.

The root cause of this event is cognitive personnel error by personnel who were responsible for the implementation of a new LRW discharge monitor computer in 1985.

Specifically, an updated efficiency factor was not incorporated; this resulted in calculation of nonconservative setpoints for the LRW discharge monitors.

Corrective actions for this event included: 1) installing updated efficiency '

factors into system software, 2) examining ten percent of past LRW discharge permits which demonstrated a high probability that no Technical Specifications instantaneous discharge rate limits had been exceeded and 3) revising procedures 62CI-CAL-001-05, Liquid Radwaste Monitor, 64CH-ADM-001-0S, Chemistry Program, and 64CH-ADM-002-0S, Chemistry Forms,.to be completed by 1/31/90, and 4) counseling involved personnel.

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SUMMARY

OF EVENT On 11/28/89 at approximately 1600 CST, Unit 1 was in the Run mode at an approximate I power level of 2436 MWt (approximately 100 percent of rated thermal power) and Unit 2 was in cold shutdown at an approximate power level of 0 MWt. At that time, plant chemistry personnel, while determining efficiency factors for newly installed liquid radwaste (LRW) discharge radiation monitors (EIIS Code MON), found that the efficiency factors which had been used for the old monitors were incorrect. This  ;

discrepancy was found to apply to both units and resulted in the isolation setpoint of the LRW discharge monitoring instrumentation, which is a backup to isotopic .

analysis of the discharge tank, being less conservative than is required by Unit 1 1 Technical Specifications section 3.14.1 and Unit 2 Technical Specifications section i 3.3.6.9. -

The root cause of this event is cognitive personnel error by personnel who were responsible for the implementation of a new LRW discharge monitor computer in 1985.

Specifically, an updated efficiency factor was not incorporated; this resulted in calculation of nonconservative setpoints for the LRW discharge monitors.

Corrective actions- for this event included: 1) installing updated efficiency ,

. factors into system software, 2) examining ten percent of past LRW discharge permits  !

which demonstrated a high probability that no Technical Specifications instantaneous ,

discharge rate limits had been exceeded and 3) revising procedures 62CI-CAL-001-OS, Liquid Radwaste Monitor, 64CH-ADM-001-0S, Chemistry Program, and 64CH-ADM-002-OS, Chemistry Forms, to be completed by 1/31/90, and 4) counseling involved personnel.

DESCRIPTION OF EVENT

!- On 11/28/89, plant chemistry personnel completed installation and calibration of new monitors in the LRW discharge monitoring instrumentation channels. During the calibration process a determination is made whether the monitor efficiency factor ,

needs, to be modified. During a follow up review of the calibration by chemistry personnel it was discovered that the incorrect efficiency factor had been in use since 1985. This resulted in the setpoints for the LRW discharge monitors being set such that they might not initiate an isolation of the discharge line prior to the potential exceedance of Technical Specifications instantaneous limits as specified #

in 10 CFR 20, Appendix B, Table II (column 2). This isolation function is required by sections 3.14.1 and 3.3.6.9 of the Units 1 and 2 Technical Specifications, respectively.

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l Prior to any discharge of liquid radwaste, an isotopic analysis of the radionuclide content of the discharge tank is performed to provide the primary -

assurance that release of the tank contents will not exceed the previously referenced Technical Specifications limits. This analysis is performed by the LRW discharge monitor computer and is independent of the discharge monitor efficiency factor. As a backup, and independent of the isotopic analysis, a separate calculation which uses the previously referenced efficiency factor, is performed by the LRW computer to determine the appropriate setpoint for the LRW discharge monitors. The efficiency factor is based on the specific characteristics of the LRW discharge monitors. The setpoint calculation thus considers both the monitor characteristics and the specific contents of the discharge tank (i.e., each time a LRW discharge is made the monitor is set to a unique setpoint).

Plant chemistry personnel determined that the current, correct efficiency factor had been calculated originally in slune, 1985. The efficiency factor had been calculated at that point to reflect a new method of determining the LRW discharge mnnitor's efficiency using a liquid Cesium 137 standard source. This efficiency '

factor was documented on a data sheet to be referenced in subsequent calibrations of the LRW discharge monitor and was input into the Hewlett Packard Model 9845 computer, on 6/28 and 6/29/85 respectively for Units 1 and 2, which at that time was the LRW discharge monitor computer.

However, at the same time, a new computer system (manufactured by Nuclear Data ,

Corporation and referred to herein as the ND system) was being prepared to replace the HP system. The ND system was required to accomodate the NRC required implementation of the new Radiological Effluent Technical Specifications (RETS).

In order to support performance testing of the ND system, an efficiency factor based on actual radwaste tank content (efficiency factor calculation method prior to method using a standard Cesium 137 source) had been input to the ND computer on 4/30/84.

On 6/28/85, plant chemistry personnel received notification from the NRC which implemented RETS. Such implementation had to be accomplished prior to the start of a new quarter due to the reporting constraints of RETS. Therefore, plant personnel proceeded to implement the new ND system on an accelerated basis. ND system experts performed functional tests between 6/28 and 6/30/85 which accomplished their function of assuring the adequacy of the software and hardware. However, the ND system experts failed to input the correct efficiency factor, just calculated based on the Cesium 137 source. Therefore, the ND system was implemented on 7/01/85 but the efficiency factor input on 4/30/84 was not corrected.

Differences in output between the ND and HP systems did not alert personnel to the use of the incorrect efficiency factor and could not have been expected to. The differences seen, which were less than an order of magnitude, were expected due to the differences in setpoint calculation methods employed. The monthly calibrations of the monitor instrumentation require confirmation that the efficiency factor does not need to be changed; however, this factor is rarely expected to change since the characteristics of the monitoring instrumentation are generally stable (replacement of the detector portion of the instrumentation on 11/28/89 was the first instrumentation change since 1985 expected to have some

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Upon discovery of the incorrect efficiency factors in the ND system, the correct efficiency fattors for Units 1 and 2 were installed into the system software.

CAUSE OF THE EVENT The root cause of this event is cognitive personnel error by the personnel who were responsible for implementation of the ND system in June,1985. These individuals failed to assure that the current efficiency factors for Units 1 and 2 had been correctly input into the ND system prior to implementation. This is concluded to be an isolated event due to the unique and technically complex function of the LRW discharge monitor computer and the accclerated implementation schedule required due to the timing of the RETS implementation. A finsi contributing factor wai, the change in the method of determining the efficiency factor which, .due to unrelated circumstances, occurred in parallel with the implementation of RETS.

REPORTABILITY ANALYSIS AND SAFETY ASSESSMENT This report is required per 10 CFR 50.73(a)(2)(1) because a condition existed' that was prohibited by the plant's Technical Specifications, Spec =lfically, the inadvertent use of an incorrect efficiency factor resulted in the setpoints for the LRW discharge monitor being set such that the requirements of Units 1 and 2 Technical Specifications sections 3.14.1 and 3.3.6.9, respectively, were not met.

The setpoints might not properly initiate an isolation of the discharge line prior to the potential exceedance of Technical Specifications instantaneous limits as specified in 10 CFR 20, Appendix B, Table II (column 2).

The function of the LRW discharge monitor instrumentation is to provide an isolation signal in the event sn unexpectedly high concentration of radioactive material is detected in the discharge piping. This is an unlikely Ovent due to the batch process nature of LRW discharges. Isotopic analyses are used to determine the radionuclide content of a LRW discharge tank prior to its release to assure compliance with the previously referenced Technical Specifications limits.

The LRW discharge monitor provides a backup to this analysis to ensure that radionuclide content of the effluent does not differ greatly from that of the isotopic analysis. The monitor is located on the LRW discharge piping upstream of the diletion influent piping and is designed to initiate a trip of isolation valves should the radiation count rate exceed a predetermined level. The LRW discharge monitor thereby serves to ensure instantaneous discharge rates do not exceed Technical Specifications limits.

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l c Reviews have been conducted on a sample of radiological discharge data dating back

.to July,1985. - The highest release concentration averaged over any three-month ,

period since July,1985 was less than seven percent of that permitted by  !

10 CFR 20, Appendix B,' Also, approximately- ten.-percent.of recorded instantaneous '

~ count . rates _for post-1985 releases (600 out of approximately 6000-releases), as )

seen by the' subject LRW discharge monitors, have been reviewed against a recalculated isolation setpoint based on corrected monitor efficiency factors.

This ten percent sarple consisted of a review of alll discharges made during the previously referenced three-month period with the highest average release .

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concentration and; selected othor discharges with potential for exceedi_ng Technical Specifications limits. No event was found whertir. instantaneous release . rates exceeded the Technical Specifications limits.- Based on this sample size, there is a- greater. than 98% confidence level that greater than 99% of the releases were

?within the permissible radionuclide releasc limits prescribed in 10 CFR 20.

Based on the above analysis, it is' concluded that this event had .no adverse impact on nuclear; safety. Since the power level of the units would not have changed the nature of the event, it is concluded that the event would not have.been more

. severe under other operating conditions.

CORRECTIVE ACTIONS Corrective actions for this event included:

1) ' installing a correcte'd efficiency factor into ND system software.

This action hs been completed.

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2) examining ten percent 'of LRW discharge permits since July 1985 (600 out of approximately 6,000 relea^,es) to determine whether any had exceeded Technical Specifications instantaneous discharge e rate li' nits. None were found to have exceeded applicable limits.

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3)' Revising 62CI-CAL-001-0S, Liquid Radwaste Monitor, 62CH-ADM-001-0S,

. Chemistry Program, and 64CH-ADM-002-0S, Chemistry Forms, to require periodh comparison of current efficiency factors with those actually in the LRW discharge monitor computer software. This

, action will be completed by 1/31/90.

4). Personnel involved in this event who are still employed at Plant Hatch have been counseled as to the consequences of their actions.

A_DDITIONAL INFORMATION No plant equipment other than the LRW c1scharge monitore was affected by this event.

No previous similar events were identified.

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