IR 05000237/1991024
| ML17174A984 | |
| Person / Time | |
|---|---|
| Site: | Dresden  |
| Issue date: | 11/13/1991 |
| From: | Burgess B NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| To: | |
| Shared Package | |
| ML17174A983 | List: |
| References | |
| 50-237-91-24, NUDOCS 9111260140 | |
| Download: ML17174A984 (5) | |
Text
U. S. NUCLEAR REGULATORY COMMISSION REGION. III Report N /91024(DRP)
Do~ket N License No. * DPR-19 Licensee:
Commonwealth Edison Company Opus West III 1400 Opus Place Downers Grove, IL 60515 Facility Name:
Dresden Nuclear Power Station, Unit 2 Inspection At:
Dresden Site, Morris, IL Inspection Conducted:
September 1 through October 29, 1991 Inspector:
W. G. Rogers Approved By:~~r B. L. Burgess, ief Projects Section lB Date Inspection Summary Inspection durin~ the period of September 1 through October 29, 1991 (Report No. 50-2 7/91024(DRPT).
Areas Inspected: Special unannounced resident inspection of the circumstances surrounding four high steam line reactor protection/containment isolation channels being rendered inoperabl Results:
One apparent violation - Technical Specification 3.1.A.1. Limiting condition for operation (LCO) was not me (P~ragraph 5).
9111260140 911114 PDR f;DOCJ<. 05000::.:-!37 Q
- DETAILS Persons Contacted Commonwealth Edison Company
- E. Eenigenburg, Station Manager
- L. Gerner, Technical Superintende~t E. Mantel, Services Director
- D. Van Pelt, Assistant Superintendent - Maintenance
- J. Kotowski, Production Superintendent J. Achterberg, Assistant Superintendent - Work Planning
- G. Smith, Assistant Superintendent-Operations The inspector also talked with and interviewed several other licensee employees, including members of the technical and engineering staffs; reactor and auxiliary operators; shift engineers; foremen; electrical, mechanical, and instrument personnel; and contract security personne *Denotes those attending one or more exit interviews conducted informally at various times throughout the inspection perio.
Background There are four steam lines from the reactor to the common steam header for Unit Each steam line has one radiation monitor to sense fuel failur When two of the four monitors sense high radiation, the rea*ctor scram and Group I isolation (main steam isolation valves closure) logic/trip circuits are actuate The trip setpoint for the radiation monitors is 3 times backgroun Unit 2 at Dresden uses hydrogen addition into the reactor coolant system to reduce intergranuJar stress corrosion cracking of the reactor recirculation piping.* However, the additional hydrogen substantially increases the background radiation in the the steam lines by increasing the noncondensible gases/gamma radiation fiel Therefore, there are two trip setpoints (3 times background) for the steam line radiation monitors depending upon whether hydrogen addition is in service (high background) or out of service (low background). Description of Event At 8:25 a.m., on August 20, 1991, with the Unit 2 reactor at 94% power, instrument mechanics (IMs) and an observer received authorization from the operating shift to perform the quarterly calibration of the main steam line radiation monitor The calibration is required by the Technical Specificatio At 9:00 a.m., hydrogen addition to the reactor coolant system was secured to support the calibratio As part of
the calibration procedure the as-found dual setpoints were to be checked.with the previous as-left setpoints. Therefore, the procedure instructs the technician to obtain the previous calibration data sheets and.enter the setpoints on the new data sheet The previous setpoints were obtained and entered on the new data sheet When transcribing data for the required trip setting and acceptable range columns, the previous setpoints/acceptable ranges, not the newly calculated ones, were entere These numbers should have been entered later in the performance of the procedur Interviews with the licensee indicate that the observer asked the technician where data was to be inserted and how to do the calculations, which may have contributed to the error The Table below indicates the correct setpoints versus what the setpoints were left a As the Table reflects, the error in transcribing did not render the "without H2 addition" trip function inoperable but only the "with H2 addition" trip functio STEAMLINE
- ACTUAL AS-LEFT SETPOINT
- SETPOINT IT SHOULD BE
--------------------------:--------------------------
8502 mr with H2 8300 mr with H2 A
1740 mr without H2 1973.7 mr without H2
:--------------------------:--------------------------
11139 mr with H2 B
2450 mr without H2 10900.mr with H2 2634.3 mr without H2
-~-----------:--------------------------:--------------------------
8880 mr with H2 8598.9 mr with H2 c
1760 mr without H2 1993.8 mr without H2
~----------------:----------~---------------
9290 mr with H2
.
8807.4 mr with H2 D
1860 mr without H2 2079.6 mr without H2
All four channels were non-conservatively set by 202, 239, 28 and 482.6 mr respectively with hydrogen injection in servic The surveillance was partially performed by the dayshift !Ms with work stopping at the point of transferring data for the new alarm and trip setpoint The dayshift supervisor reviewed the calculations for the new setpoints and approved the The dayshift IM understood th_at the setpoints should be changed but this information was lost in the turnove When the afternoon IM reviewed the procedure he saw that the
"new" setpoints had been transferred but these were really the old setpoint The afternoon IM checked that the 11 new 11 setpoints met the acceptance criteri No adjustments to the setpoints were made and the procedure was submitted to the afternoon IM supervisor for revie *
The -afternoon IM superv1spr reviewed the as-left/required data sheet for review and approva An interview with the procedure writer indicated that the supervisor 1 s signature on the data sheet was for assuring that all blocks were completed. and Technical Specifications me An interview with the supervisor indicated that he reviewed the data for completion and whether the acteptance criteria were met (in this instance, the acceptance criteria was wrong)~ The surveillance was signed off at 5:50 p.m., on August 20, 1991, by the IM afternoon supervisor and the shift superviso An operational functional test was performed and hydrogen addition was placed back into service at 8:00 During the post implementation review process, the department surveillance coordinator identified the improper setpoints on August 21, 199 The*
Shift Engineer was contacted and another calibration begun at approximately 2:00 p.- An emergency notification system (ENS) notificatibn of the event was made at 2:35 At 4:55 p.m., the setpoints were changed to the proper, more conservative calculation result.
Analysis of R~~t Cause The inappropriate personnel action was caused by a number of factors: There was an observer present during the surveillance which provided additional stress on job performanc The procedure quality was poo The procedure was vague as to where to record the old surveillance procedure results and where the new calculation results-were to be use The delineation of the acceptance criteria was not in close proximity to the test results and was intermixed with other dat This increased the difficulty in reviewing the results of the surveillanc The management contro_l system was inadequate in detecting the inappropriate personnel action before placing the equipment back into servic The supervisor 1 s review of the information did not detect the error in acceptance criteri *An essential piece of information was lost in the turnover proces The management control system was inadequate in minimizing the consequences of an inappropriate personnel action.
The surveillance activity was allowed to occur on all four channels at the same tim No controls were in place to review the results for acceptability between performance on each channe The same individual was used to perform the surveillance on all four channels allowing one mind-set to affect all the channel The same test instrumentation was used to calibrate all four channel If the test instrument had been improperly calibrated, the calibration of all four channels could have been invali.
Assessment of Safety Significance This event resulted in invalidation of both trip systems of a reactor protection and containment isolation input paramete Technical Specification 3.1.A.1 requires these channels to be operabl When four channels are inoperable all control rods must be inserted within 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> or main steam isolation valves closed within 5 hour5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br /> These actions did not occu Thi~ is considered an apparent violation (237/91024-0l(bRP)) of Technical Specifications. However, all-channels associated with main steamline high radiation, th6ugh inoperable, would have. tripped at a higher setpoint. Also, the Office of Nuclear Reactor Regulation recently concluded that the high steamline radiation trip function was unnecessary in a recent generic Safety Evaluation Report to General Electric topi_c report NED0-3140 The final conclusion of safety significance to the health and safety of the public in this particular instance is negligibl The Dresden design basis for minimizing offsite dose consequences relies upon the offgas radiation monitor setpoints isolating the releas These monitors were set at approximately 2230 mr for 15 minutes and were not affected by the main steam line radiation monitor setpoin Howev-er, the inadequ'acies in the management control system, including procedure quality, make other engineered safety feature systems vulnerable to one personnel error rendering the system inoperabl.
Exit Interview The inspector met with licensee representatives (denoted in Paragraph 1)
- on October 29, 1991, and informally throughout the inspection period to summarize the scope and findings of the inspection activitie The inspectors also discussed the likely informationfrl content of the inspection report with regard to documents or processes reviewed by the inspector during the inspectio The licensee did not identify any such documents/processes as proprietar The licensee acknowledged the findings of the inspectio