IR 05000280/1993001
| ML18153D249 | |
| Person / Time | |
|---|---|
| Site: | Surry  |
| Issue date: | 02/23/1993 |
| From: | Crlenjak R, King L, Curtis Rapp NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II) |
| To: | |
| Shared Package | |
| ML18153D248 | List: |
| References | |
| 50-280-93-01, 50-280-93-1, 50-281-93-01, 50-281-93-1, NUDOCS 9303020175 | |
| Download: ML18153D249 (7) | |
Text
Report Nos. :
UNITED STATES NUCLEAR REGULATORY COMMISSION
REGION II
101 MARIETTA STREET, ATLANTA'. GEORGIA 30323 50-280/93~01 and 50-281/93-01 Licensee:
. Virginia Electric and Power Company 5000 Dominion Boulevard Glen Allen, VA 20360 Docket Nos.:
50-280 and 5Q-281 Facility Name:
Surry License Nos.: DRP-32 and DRP-37 Inspection Conducted:
January 25 - 29, 1993 Inspectors:
Approved by:
Scope:
R. Crlenja, Se ion Chief Operational P gram Section Operations Branch Division of Reactor Safety SUMMARY f/'hlf3 DeSigned c;J/2-3/93-Date Signed This was a special announced inspection in the area of Plant Instrumentation Setpoints. The inspectors reviewed Channel Statistical Allowance ca lcul ati oils, calibration procedures, and set point docu.mentat ion to determine if plant setpoints were within the assumed accident analysis envelope and i the plant instrumentation was calibrated consistent with.the values assumed in the Channel Statistical Allowance calcu1ation Due to the detailed review required by this type of inspection, the inspectors limited the inspection to the instrumentation discussed in the repor Results:
The inspectors found example~ where 1) the calibration procedure was not bounded by the Channel Statistical Allowance calculation, 2) the scalings used in the calibration procedures could not be verified from plant documentation and differed from the scaling assumed in the Channel Statistical Allowance
- calculations, 3) the allowable tolerance in the calibration procedure was assumed to be a constant voltage over the entire calibrated span, and 4)
inconsistent conservatism allowance was applied to plant setpoints. While there were no setpoints that exceeded the safety analysis limit, the above examples indicated weaknesses in the setpoint progra No violations or deviations were identifie.
PDR ADOCK 05000280 O
- REPORT DETAILS
- Persons Contacted T. Abercrombie, NES-EE
- B. Benthall, Licensing Supervisor
- R. Blo~nt, Superintend Engineering
- G~ Flowers, Manager Electrical Engineering
- M. Kansler, Surry Station Manager
- W. McBride, NES-E *G. Mietus, DEO-EE
.
- J. Price, Surry Assistant Manager
- S. Roberson, On-Site Engineering, In *E. _Smith, Surry QA Manager
- B. Stanley, Supervisor Station Procedures
- E. Watts, Supervisor DEO-EE
Other licensee employees contacted included instructors, engineers, mechanics, technicians, operators, and office_ persohne NRC Representatives
- L. Lawyer, Region II
.
- J. York, Acting Senior Resident Inspector S. Tingen, Resident Inspector
- Attended Exit Interview Appendix A contains a listing of abbreviations used in this repor.
Review of Channel Statistica*l Allowance Calculations The inspectors reviewed procedure STD-EEN-0304, Calculating Instrumentation Uncertainties By The Square Root Sum Of The Squares Method Revision 1, which discus*sed the methodology for calculating CSA The procedure described each parameter and how the parameter was applied to obtain th~ CS The procedure also specified values to be used if vendor specifi~ values could not be foun The inspectors conducted a review to determine if the values used to calculate the CSA were appropriately appJied, the CSA was correctly calculated, and the setpoints were within the safety analysis limi Within the scope of this inspection, the inspectors reviewed the following CSAs:
EE-0130, LHSI Flow Indication, Revisions O and 1 EE-0179, PZR Pressure Trip, Revision 1 EE-0183, RCS Low Flow Trip, Revision 1 EE-0177, SI Accumulator Level, Revi~ions O and 1 1250-122-COlO, Charging Pump Flow Loop Accuracy Calculation, Revision 2 1250-122-C013, Charging Pump Flow Loop Accuracy Calculation, Revision 1 1250-09-Q04A, LHSI Pump Recirculation Flow Accuracy Calibration, Revision 1
2 Review of Safety Related Setpoirits 1. Pressurizer Low Pressure SI The inspectors reviewed the CSA calculation and the talibration procedure to determine if the pressurizer low pressure SI setpoint was within the safety analysis limit. The CSA calcul~tion, documented in EE-0377, indicated a 16 psig channel allowance was require The safety analysis limit for pressurizer low pressure SI wai equal to the TS limit of 1700 psi~. According to*
STD-GN-0030, Nuclear Plant Setpoints Revision 4, the setpoint was calculated using the following formula:
Setpoint value= Safety Analysis Limit - (CSA+ Conservatism)
Using this formula and the calculated CSA, the pressurizer low pressure SI setpoint should be at least 1716 psig without allowance for conservatis The inspectors reviewed DRP-005, Instrumentation Setpoints Revision 10, and found the pressurizer low pressure SI setpoint was 1715 psig which was 1 psig less than the safety analysis limit of 1700 psi While the inspectors found the 1 psig difference was not significant, the lack o conservatism required by STD-GN-0030 was of concer The lac~ of conservatism did not allow for any errors or inaccuracies in the value~ assumed in the CS The licensee stated the RPS/tSFAS setpoints were _calibrated conservatively; in this particular instance the as-left setpoint was actually 1718 psi The inspectors reviewed l-PT-2.4A, Pressurizer Pressure Protection Re~ision 1, and found the as-left setp6int was conservativ However, l-PT-2.4A only required a setpoint of 1715 psig. -The inspectors determined the licensee had inappropriately relied on the practical consideration of allowing setpoint adjustment to the nearest 0.01 Vdc as setpoint-conservatis If the-additional 3 psig was necessary, then the required setpoint should be changed to 1718 psi The inspectors reviewed the previous five 18-month sensor calibrations to determine if the sensor drift allowance assumed in the CSA was bounding compared to actual plant dat The inspectors concluded the assumed sensor drift allowance was adequat However, the inspectors noted the actual sensor drift tended to approach the assumed sensor drift allowanc Because of the lack of conservatism, the inspectors concluded sensor drift greater than allowed could likely result in operation outside the safety analysis limit. The inspectors did not identify any instances where sensor drift had exceeded the allowanc.
RCS Low Fl OW Trip The inspectors reviewed EE-0138 to determine if the RCS low flow reacto~ trip setpoint was within safety analysis limit of 87%.
The TS limit was 90% to allow for a 3% flow instrumentation error assumed in the FSA An additional 2% was added for conservatism
- which resulted in an actual plant setpoini of _92%.
The CSA
. calculated a 3.09% of span i~strumentation error ~hich was greater
..
than the error assumed in,the FSA The inspectors concluded the additional error was not significant, but reduced the overall*
conservatism in the setpoint. During a review of l-PT-2.2A, Reactor Coolant Flow Revision 1, the inspectors found the.
calibrated span used in l-PT-2.2A was less than assumed.in the.
CSA.* Because 1-PT-2.2A allowed 0.02 volts calibration error over a smaller span, this result~d in a greater calibration error allowance than ~ssumed in the CS The inspectors concluded the additional error allowance was not significant, but further reduced setpoint conservatis The inspectors revi~wed the Unit 2 procedure and found the calibrated span assumed in the CSA was used in the Unit 2 procedur. SI Accumulator Level The inspectors review of this CSA found a transmitter span of 23.83" w.c. use This was not consistent with EE-0376, SI Accumulatcir Level XMTR Spans Revision 0, ~hith calculated a span of 23.68" The inspectors recalculated the CSA using the span found in EE-0376 and determined the allowance was +/-2.43% of span instead of +/-2.28% of spa The use of an*incorrec,t span resulted in a nonconservative CSA calculatio The inspectors noted the CSA calculated using the 23.68" w.c. span was 0.029 Vdc which was greater than the a.oz Vdc tolerance assumed in 17PT-2.18, "A"
. Safety Injection Accumulator Tank Leve While the errors identified were not signifi~ant, the inspectors were concerned because the errors reduced setpoint conservatism and there was very little margin to the safety analysis limit with the current plant setpoint Any additional nonconservative assumptions or plant configuration differ-ences could result in operation outside the safety analysis.* The licensee was in the process of validating plant setpoints and Upgrading calibration procedures at the time of this inspectio This area will be reinspected when the upgrade effort is completed and is identified as IFI 50-280,281/93-0l-Ol LHSI System Flow Testing Due to concerns identified in NRC inspection report 92-06 about the ability of the Unit 2 LHSI system to meet design requirements of 3200 gpm, a special flow test was conducted on Unit During the review of the CSAs for FI-SI-1945 and 1946, the inspectors reviewed a licensee memorandum, Evaluation Of Test Results For LHSI Injection Flow Based On March 17, 1992 1PT-18.3D Test, dated March 19, 199 This memorandum indicates a measured shortfall of 32 gpm for Unit The licensee also performed a preliminary evaluation of the Unit I data and calculated 'a Unit 2 LHSI system shortfall of 252 gpm.
Shortfall is defined as the amount less than the design value stated in the FSA The licensee stated they performed an analysis to show this shortfall results in less than a 50° F penalty for the PC The inspectors reviewed the licensee's calculations and found no allowance was made for uncertainties on recirculation flow indicatio Including recirculation flow indication uncertainties would have increased the Unit 1 shortfall by 11 gpm for a total shortfall of 53 gp Because the licen~ee did not include
- 4 recirculation flow indication uncertainties which would have
- increased the shortfall to 53 gpm, the stated boundary evaluation of
- * 50° F was nonconservativ The inspectors requested a copy of the analysis for further NRC review and were given a copy of a licensee letter, Report of ECCS Evaluation Model Changes Pursuant To Requirements of 10 CFR50.46, dat~d August 31, 199 This letter stated that reducing the previously assumed low head safety injection flow would appropriately bound_;the expected flow rates for both units. The licens~e concluded~that a PCT penalty of 23°F would result from the decreased LHSI flo The inspectors were ~nable to determine if the analysis was adequate because the letter lacked specific details concerning the assumed flow reductio The NRC will monitor the Unit 2 flow test jhich was scheduled to occur in March 199 The inspectors reviewed l-PT-18.5D, Refueling Test Of The Low Head Safety Injection Check Valves To The Cold Legs, dated March 12,1992, to determine if the instru~ent uncertainties were conservativ The licensee determined that instrument string FI-SI-1945 and 1946
_exceeded the +/-2% of i ndi ca tor span required by ASME Section X As a result, EE-0130 which showed an indicator CSA of +/-2.45%, was
- recalculated using the ERF computer digital indication. The new calculation EE-0130 showed that a CSA of +/-1.8% could be achieve The inspectors review~d calculation EE-0130 Revision* 1 which documented the CSA of +/-1.8%.
All factors remained the same as in EE-0130 Revision O with the exception of the RCA term, which was replaced with the accuracy value for the ERF computer indication, and the RRA term, which was set to zer6 because the ERF computer was a digital indication~ The RCA v~lue for the ERF computer indication was taken from Technical Repo~t EE-006B, Instrument Tolerances for WestiDghouse/Hagan 7100 Process Protection*and Control System, dated February 22, 199 The inspectors concluded this approach was acceptable for the _purpose of obtaining LHSI flow rate dat.
. Review of Calibration Procedures-The inspectors reviewed the associated calibration procedures to determine if the procedures were bounded by the assumed values.in the CS The inspectors fbund that a 0.02 volt calibration tolerance was allowed for all calibration procedures. This was the vendor specified accuracy of 0.5% span for the digital voltmeters used for calibration. However, the use of a specific voltage resulted in higher calibration tolerances at lower voltages than the assumed 0.5%
span accurac The inspectors concluded that a range. of acceptable voltages for each calibration point would have mor~ appropriat The inspectors reviewed an upgraded calibration procedure and found that acceptance ranges were specified. This upgraded procedure was approved, but was not yet in us This area will be reinspected as part of IFI 50-289,281/93-0l-O All CSAs reviewed assumed a 0.5% span error tolerance for digital multimeters used for voltage measurement The inspectors interviewed the MT&E personnel and reviewed a certificate of calibration for the 51008 Series Calibrator used to calibrate the digital multimeter The report of calibration showed that it was
within specifications. Heise pressure gages used for instrument
.
-calibration were calibrated to the 0.1% accuracy assumed in the CSA calculations. The tester used for calibrating Heise pressure*gages was calibrated to 0;025% meeting the 4-to-l accuracy requiremen During the review of the calibration procedures, the inspectors noted the accuracy of the equipment to be used for calibration was not specifie The inspectors concluded the lack of specific calibration equipment or accuracies was a weaknes The inspectors reviewed an upgraded calibration procedure which did specify the calibration equipment or accuracies.* This upgraded procedure was approved, but
- was not yet in us This area will be reinspected as part of IFI 50-280,281/93-01-0 The inspectofs reviewed the calibrated spans used in the calibration procedure and found they lacked supporting plant documentatio Incorrect instrumentation scaling could result in setpoints outside the safety analysis limits. However, based on the review, the inspectors concluded the scalings would have to have significant errors for the setpoint to be outside the safety analyiis limit The licensee was in the process of verifying the scalings.* Plant instrumentation scalings will be reinspected as part of IFI 50-280,281/93-01-0l.
. Review of Setpoint Control Program The inspectors reviewed SUADM-ENG-04, *setpoint Control.P~ogram Revision l, to determine the method used to modify setpoint The inspectors.found setpoints were controlled through the DCP or EWR process:
Whenever a DCP or an EWR was performed indicating a change to plant instrumentation, the setpoint was evaluated for modification: The inspectors found.these controls to be adequate; however, the inspectors did note an exception to the DCP/EWR *
control SUADM-ENG-04 allowed the modification of an existing setpoint if a veridor document indic~ted a different setpoirit and the existing setpoint could not be validated without a DCP or EWR. *The concurrence of the System Engineer or Setpoint Coordinator was require The inspectors concluded this allowance was unacceptable because it circumvented the intent_of the Setpoint Control Program..
. Exit Meeting The inspection scope and finding were summarized on January 29, 1993 with those persons identified in Paragraph The inspectors described the areas inspected and discussed in detail the inspection
_ finding No proprietary material was reviewed by the inspectors.
ITEM IFI 93-01-01 STATUS OPEN
. DESCRIPTION REVIEW OF UPGRADED -
CSAs, SETPOINTS, AND CALIBRATION PROCEDURES
II ASME CSA DCP ESFAS ERF EWR FI FSAR LHSI MT&E NRR PCT RCA RCS RPS RRA SCA SI TS Vdc APPENDIX A inches water column American Society Of Mechanical Engineers Channel Statistical Analysis Design Change Package Engineered Safety Features Actuation System Emergency Response Facility Engineering Work Request Flow Indicator Final Safety Analysis Report Low Head Safety Injection
- Measurement Test and Equipment Office of Nuclear Reactor Regulation Permissible Core Temperature Rack Calibration Accuracy Reactor Coolant System Reactor Protection System Rack Readability Allowance Sensor Calibration Accuracy Safety Injection Technical Specifications Volts Direct Current