ML20071P082

Final Significant Deficiency Rept Re Lockup of RM-23 Display in Radiation Monitoring Sys.Initially Reported on 830223.Circuit Boards Returned to Vendor for Mod & Testing. Modified Boards Will Be Installed Prior to Fuel Load

ML20071P082
Person / Time
Site:	Wolf Creek, Callaway
Issue date:	05/27/1983
From:	Seiken S STANDARDIZED NUCLEAR UNIT POWER PLANT SYSTEM
To:	Jay Collins, James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III), NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV)
References
10CFR-050.55E, 10CFR-50.55E, SLNRC-83-031, SLNRC-83-31, NUDOCS 8306070345
Download: ML20071P082 (7)

Text

, ,*

SNUPPS Standardised Nuclear Unit Power Plant System s chas ch.ny no.d May 27, 1983 Rodville, Maryland 20850

" ' ' " SLNRC 83-031 FILE: 0491.10.2 SUBJ: Final Report: Lock-up of the RM-23 Display in the Radiation Monitoring System (SDR 83-04)

Mr. . lames G. Keppler Administrator, Region III U.S. Nuclear Regulatory Commission 799 Roosevelt Road Glen Ellyn, Illinois 60137 Mr. John T. Collins Administrator, Region IV U.S. Nuclear Regulatory Commission Suite 1000, Parkway Central Plaza Arlington, Texas 76012 Docket Nos. STN 50-482 and STN 50-483 Ref: SLNRC 83-016, 3/22/83: Same Subject Gentlemen:

The referenced letter provided an interim significant deficiency report to NRC Region III and Region IV representatives. The report was filed on behalf of Union Electric Co. (UE) and Kansas Gas and Electric Co. (KGE) and is applicable to the Callaway and Wolf Creek Radiation Monitoring Systems. The reported deficiency involves a display lock-up associated with the RM-23 control / display module which could give control _ room operators an erroneous indication of channel activity for ten safety-related radiation monitors.

Attached is the final report concerning this deficiency. Please note that tests performed by the vendor, G.A. Technologies, have confirmed that pro-posed modifications to a circuit board in the RM-23 control / display module will correct the software design deficiency. Current plans are to return these circuit boards to the vendor for modification and testing, and to install the modified circuit boards at Wolf Creek and Callaway prior to fuel loading. In addition to the control / display modules which have been shipped to Callaway and Wolf Creek, several. modules have not yet been shipped to the SNUPPS sites. These unshipped control / display modules will be modified prior to shipment.

Very truly yours, 8306070345 830527 M PDR ADOCK 05000482 S

S. J. Seiken PDR Manager, Quality Assurance L RPW/dck8b12 /g (

Attachment cc: ' Page Two M g jggg 6

SLNRC 83 031 Page Two cc: D. T. McPhee, KCPL G. L. Koester, KGE D. F. Schnell, UE H. W. Roberds, USNRC/WC J. H. Neisler, USNRC/ Cal H. M. Wescott, USNRC Region III kichard DeYoung, Director I&E Record

FINAL REPORT ON THE LOCK-UP 0F THE RM-23 DISPLAY IN THE RADIATION MONITORING SYSTEM PER 10 CFR 50.55(e)

SNUPPS PROJECT

TABLE OF CONTENTS PAGE

1.0 INTRODUCTION

1

2.0 DESCRIPTION

OF RM-23 READ 0UT 1

3.0 DESCRIPTION

OF DEFICIENCY 2 4.0 SAFETY IMPLICATIONS 2 5.0 RESOLUTION AND CORRECTIVE ACTION 2

6.0 CONCLUSION

S 3 RPW/dck/9b24

1.0 INTRODUCTION

In compliance with 10CFR50.55(e), this report is being issued as a result of an anomaly observed in the RM-23 display during the start-up of General Atomics Technologies Inc. (GA) Radiation Monitoring System at a Non-SNUPPS nuclear power plant. Identical RM-23 control / display modules have been delivered to the Callaway and Wolf Creek jobsites and the same defect is present in these units.

On February 23, 1983, Union Electric Co. (UE), and Kansas Gas and Electric Co. (KGE) notified NRC Region III and Region IV of a deficiency involving the lock-up of the RM-23 display in the radiation monitoring system. An interim report was submitted to the two NRC regions on March 22, 1983.

GA has also reported the problem, pursuant to 10CFR21 reporting requirements.

2.0 DESCRIPTION

OF RM-23 READ 0UT The Class lE RM-23 module is a complete microcomputer that is capable of making logical decisions according to instruc-tions contained within its memory. The RM-23 module is used to provide display and control of safety-related digital radiation monitoring data. The RM-23 modules are located in the control room.

. - - ,,,_y - . , - - - - , , - . . - - - - - - . y -,

? %e Specifically, the RM-23 functions are as follows:

a. Provides digital display

b. Command control of monitor functions

c. Loading or changing of the digital radiation monitor data base

3.0 DESCRIPTION

OF DEFICIENCY During start-up of one of the GA Radiation Monitoring Systems at a Non-SNUPPS nuclear power plant, an intermittent lock-up of the RM-23 digital display was observed. The lock-up caused the channel activity display to freeze at the most recent activity value for each channel.

4.0 ANALYSIS OF SAFETY IMPLICATIONS The control room RM-23 display lock-up deficiency could give an erroneous indication of the channel activity for the ten safety-related radiation monitors. The safety isolation function of the monitors is not affected.

5.0 RESOLUTION AND CORRECTIVE ACTION GA has conducted an extensive testing and design review to resolve the deficiency and has concluded that the defect is with the RM-23 software.

Modified RM-23 software has been developed to prevent the

~

conditions which caused the lock-up. Additionally, a re-start feature has been incorporated which detects that a lock-up has occurred and automatically re-starts the RM-23. This change eliminates the potential for future undetected lock-ups. The RM-23 with the modified software was powered and operated continuously for several weeks with completely satisfactory results.

In order to rectify the deficiency, the RM-23 control / display modules are being returned to GA for rework and modification at their facility.

6.0 CONCLUSION

S The Class lE RM-23 control / display modules were found to have a software deficiency that, if allowed to exist, would give an erroneous indication in the control room and would render the RM-23 display module unserviceable. The correction will assure that all the RM-23 control / display modules will function as designed, and satisfy their safety design basis.