IR 05000400/1990003
| ML18009A395 | |
| Person / Time | |
|---|---|
| Site: | Harris  |
| Issue date: | 03/07/1990 |
| From: | Belisle G, Burnett P NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II) |
| To: | |
| Shared Package | |
| ML18009A394 | List: |
| References | |
| 50-400-90-03, 50-400-90-3, NUDOCS 9003210046 | |
| Download: ML18009A395 (12) | |
Text
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+y*y4 UNITED STATES NUCLEAR REGULATORY'COMMISSION
REGION II
101 MARIETTASTREET, N.W.
ATLANTA,GEORGIA 30323 Report No.:
50-400/90-03 Licensee:
Carolina Power and Light Company P. 0.
Box 1551 Raleigh, NC 27602 Docket No.:
50-400 Facility Name:
Harris
License No.: NPF-63 Inspection Conducted:
February 5 - 9, 1990 Inspector:
Burnett Date Signed Approved by:
G.
A.
Be isle, Chic Test Programs Section Engineering Branch Division of Reactor Safety at Signed SUMMARY Scope This routine, unannounced inspection addressed the core performance tests performed during the cycle 3 startup and concomitant calibrations of nuclear instruments.
Results The zero power and power escalation tests performed satisfied the essential elements of ANSI/ANS-19.6. 1-1985, Reload Startup Physics Tests for Pressurized Water Reactors.
That the tests performed were controlled by a flexible sched-ule rather a test sequencing procedure was identified as a programmatic weak-ness that contributed to a period of operation in which the high flux trip setpoint was greatly in excess of the limiting safety system setting of technical specifications.
A heed for improved methods of anticipating and compensating changes in leakage flux to obtain defensive pre"startup recalibration of the power range nuclear instruments was identified.
No violations, or deviations wer e identified.
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REPORT DETAILS 1.
Persons Contacted Licensee Employees
- J. Collins, Manager, Operations
- B. DelCastilho, Principal Engineer, Technical Support
- G. Forehand, Director guality Assurance/guality Control
- J. Garcia, Reactor Engineer
"M. Hamby, On-Site Nuclear Safety
"C. Hinnant, Plant General Manager
- A. Howe, Compliance Specialist, Regulatory Compliance C. Mittag, Reactor Engineer R. Richey, Site Manager
- D. Tibbets, Director, Regulatory Compliance
"B. Van Metre, Manager, Technical Support M. Wallace, Senior Specialist, Regulatory Compliance
- L. Woods, Technical Support Other licensee employees contacted included engineers and office personnel.
NRC Resident Inspectors
- M. Shannon, Resident Inspector J.
Tedrow, Senior Resident Inspector
"Attended exit interview on February 9, 1990.
Acronyms and initialisms used throughout this report are listed in the last paragraph.
2.
Documents Reviewed The following documents were reviewed to obtain background information on and to confirm the acceptance criteria used in the tests described in the subsequent paragraphs of this report:
WCAP-12332, The Nuclear Design and Operations Package for Shearon Harris Nuclear Plant, Cycle 3.
Excore instrumentation is discussed on page 2-3 of this report, with particular emphasis on the effect of reduced neutron leakage on ion chamber response.
The report stated,
"An alignment of the channels should be performed prior to criticality to assure that the Reactor Protection System is unaffected."
The report continued with equations for correcting power range channel setpoints by about 305 and for correcting the
intermediate range channels by about 8<.
The latter correction was not intended to adjust for the lateral relocation of the source range and intermediate range instrument canisters about 21 inches farther from the core.
That activity was performed in a successful attempt to reduce the initial count rate of the SRNIs so that they would remain on scale throughout the approach to criticality (see PCR-4957 paragraph S.a).
This report was also the source of the numerical acceptance criteria for such ZPPTs as ITC, MTC, control rod worths, and CB at ARO.
VANTAGE-5 Reload Transition Safety Report for the Shearon Harris Nuclear Power Plant, February 1989.
3.
Zero Core Operating Limits Report (Revision 0).
Power Physics Test Performed for Cycle 3 (72700, 61708, 61710)
The completed ZPPTs discussed below were reviewed by the inspector and discussed with licensee personnel:
EPT-069 (Revision 1), Initial Criticality, was reviewed in its completed form.
In general, the Prerequisites and Precautions and Limitations sections were well defined.
However, neither addressed EPT-008, Intermediate Range Detector Setpoint Verification, nor was it listed in the Reference section (see paragraph 5).
Good features of this procedure included a step to assure that the VCT was not over-diluted by spray flow in the alternate dilute mode and a section to perform statistical analyses of the SRNIs to confirm acceptable operation prior to safety rod withdrawal.
Prior to safety rod withdrawal, the average countrates on SRNIs N31 and N32 were 417 cps and 275 cps, respectively.
At the end of rod withdrawal, with control bank D at 200 steps, the countrates were 21,910 cps and 14,149 cps, respectively.
Both channels indicated an ICRR of 0.019 and had tracked together throughout the rod withdrawal process.
At that point, the procedure required a determination of new reference countrates for monitoring the dilution to criticality.
Ten observations of countrate were made for each channel and averaged to obtain the reference values
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No determination of statistical reliability was requi,red by the procedure at that point, and none was done.
However, the inspector did perform the Chi-squared analysis, and both channels gave acceptable results.
During the dilution to criticality, both SRNIs responded similarly and produced consistent values of ICRR.
The data on data sheet 8. 11 of the procedure did not provide convincing evidence that a full decade of overlap had been obtained between the SRNIs and the IRNIs.
However, discussion with the test engineer confirmed that P-6 had been obtained with the SRNIs below the trip set point of 100,000 cps.
Since P-6 isset at 1.0E-10
amperes for both IRNIs and the bottom of the scale is at 12.0E-11 amperes; acceptable overlap was confirmed.
Criticality was achieved below P-6, which means that the SRNIs were able to track and monitor the entire approach to criticality.
The efficacy of the modifications performed under PCR-4957 (see paragraph 5) was proved.
b.
EPT-067 (Revision 1),
Boron Endpoint Measurement, was performed to determine the ARO C
.
The measured value of 1841 ppmB was in good agreement with the predicted value of 1849 ppmB.
EST-703 (Revision 3),
Moderator Temperature Coefficient after Each Refueling, confirmed that the MTC was less than the 5 pcm/~F, with ARO, allowed by TS 3. 1. 1.3.
The ITCs measured during one heatup and one cooldown of the RCS were -0.938 and -0. 118 pcm/'F, respectively.
The two measurements agreed within
pcm/~F, a
commonly applied industry standard, which was not an acceptance criterion in the test as written.
The average ITC was corrected for a calculated DTC of-1.6 pcm/
F to arrive at the reported MTC of +1.072 pcm/
F.
d.
EPT-068 (Revision 1), Reactivity Worth of the Control and Shutdown-Banks Utilizing the Rod Swap Technique.
The reactivity worth of shutdown bank A,
the reference bank, was measured during boron dilution of the RCS.
The measured worth was 1344 pcm, which was in good agreement with the predicted value of 1368 pcm and satisfied the acceptance criterion of 10 o agreement.
All other bank reactivity worths. were determined by rod-swap comparison with the reference bank.
All individual rod worth determination acceptance criteria were satisfied with ease.
The sum of all bank worths agreed with prediction within 2% of the sum.
The acceptance criterion was agreement within 10:.'f the sum.
No violations or deviations were identified.
4.
Power Distribution Monitoring during Power Escalation (61702)
EST-710 (Revision 7),
Hot Channel Factor Tests, was performed five times during cycle 3 power escalation at nominal power levels of 35, 50, 75, 90, and 100 percent RTP.
In all cases, the relationship F
(z) <= 2.45"k(z)/P"w(z)
was satisfied.
M Q
However, during the escalation from 90 to 100 percent RTP, the ratio FQ (z)/k(z) increased from 2.205 to 2.212.
Pursuant to TS 4.2.2.2e and TS M
4.2.2.2f, power was first reduced to 97 percent RTP.
Subsequently, the licensee exercised the equally acceptable option of reducing -the allowable AFD bands and returned to full power.
Throughout power escalation, FdH remained within limits for both the new VANTAGE 5 fuel and the recycled LOPAR fue No violations or deviations were identified.
5.
Nuclear Instrument Calibrations (61705)
The following procedures and activities pertinent to nuclear instrumenta-tion operation and calibration were reviewed:
PCR-4957, Source Range Detector Repositioning, was performed as a
temporary modification pending evaluation of the results.
Two instrument canisters (each containing a
source range detector, an intermediate range detector, and a
NFMS detector)
were withdrawn laterally from the core the maximum
inches possible and fixed in position.
The work instructions included a requirement to perform EPT-008 to correct the IRNI power calibrations for the reduced flux levels at the detectors.
That procedure was not completed prior to startup.
However, work equivalent to that required by the procedure was performed; so the IRNIs responsded acceptably at startup.
The modification was successful in that the SRNIs had sufficient countrate to monitor the cold core and remained on scale until after criticality was achieved.
b.
OST-1004 (Revision 3),
Power Range Heat Balance, was first performed for cycle 3 at 0330 hours0.00382 days <br />0.0917 hours <br />5.456349e-4 weeks <br />1.25565e-4 months <br /> on December 23, 1989.
The heat balance indicated actual power was 41.5%
RTP with an average PRNI indication of 24.8%.
The ramifications of the error in PRNI calibration are addressed in Inspection Report 50-400/90-01 and included operating for nearly three days with high flux trip setpoints greatly in excess of the LSSS.
The error was a consequence of not adjusting the gains in the PRNI instrument drawers for the anticipated reductions in core leakage prior to restart (see document 2.a)
by performing EPT-008.
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Review of tests completed over the succeeding three weeks confirmed that the daily heat balance was performed with acceptable frequency during that period and that there were no recurrences of the PRNIs being miscalibrated
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The heat balance calculation is performed by using the plant computer for data collection to the extent possible.
The actual calculation is performed offline using a microcomputer.
The inspector obtained a
copy of the program listing for review and evaluation in the regional office.
EST-717 (Revision 3),
Incore-Excore Detector Calibration, was per-formed on December 30, 1989, using incore flux maps 116 to 124, inclusive, except for map 118, which was not used.
The actual power level for the tests averaged about 73%
RTP, but the excore chamber currents were normalized to 100%
RTP.
The quality of the test was clearly improved over the one performed at the start of cycle 2 (see Inspection Report 50-400/89-18, paragraph 3).
The correlation coefficients were all in excess of 0.99.
Full-power, zero-offset chamber currents ranged from 119 to 169 microamperes.
Near the end of cycle 2, the same currents ranged from 171 to 242 microampere The reduction in current was consistent with that predicted as a
consequence of installing a
low-leakage core (see document 2.a).
However, there appear to be other effects at work in addition to the reduction in leakage.
The slopes of the correlations of current with axial offset have changed.
The average slope of an upper chamber changed from 0.784 microamperes/'oAFD to 0.614 microamperes/:oAFD.
The change in the average lower chamber slope was from -1.384 micro-amperes/:.'AFD to -0.986 microamperes//oAFD.
d.
EST-719 (Revision 3),
Incore Versus Excore Axial Flux Difference Comparison, was performed at 90 percent power and at 100 percent power on January
and 9, 1990, respectively.
Satisfactory perfor-mance was obtained from each test, and no recalibration was necessary.
No violations or deviations were identified.
6.
Summary (72700)
The zero power and power escalation tests performed for cycle 3 satisfied the essential elements of ANSI/ANS-19.6. 1-1985, Reload Startup Physics Tests for Pressurized Water Reactors.
One measurement not reported by the licensee, but calculable from the data obtained during the rod worth measurements, was the boron reactivity worth or differential boron worth.
These test and measurements were not driven by a master-plan procedure or procedures, common practice within the industry.
Instead, testing was driven by a
schedule, which had the apparent advantage of having more flexibility with respect to sequencing tests and activities and dropping activities than a
procedure-managed program would have provided.
This flexibility led to a
schedule restraint on changing PRNI trip setpoints being eliminated.
That restraint could have prevented operating with the high flux trip in excess of the LSSS.
Similarly, a
procedurally imposed requirement to account for core changes from one cycle to the next, by performing EPT-008 for example, would have prevented any operation with the PRNIs significantly miscalibrated.
Clearly, the startup test program requires enhancement.
It seems likely that from the end of one cycle to the beginning of another there will always be changes in the leakage characteristics of the core which will require a defensive recalibration of the PRNIs prior to restart.
In the future, the magnitude of the changes in leakage may not be as great as those seen going from EOC2 to BOC3.
However, other recent test results indicate that the axial as well as radial changes in leakage flux should be considered to assure representative power sharing between the upper and lower ion chambers.
Otherwise numerous gPTR alarms may be genera'ted prior to completing the incore-excore correlation above
percent RTP.
7.
Followup of Inspector Identified Items (92701)
(Closed)
Inspector identified item 50-400/88-35-01:
Review and consider methods to reduce the flux at the SRNI PCR-4957, Source Range Detector Repositioning, was completed during the recent outage and accomplished the desired goal.
See also paragraph 5 of this report.
Exit Interview (30703)
The inspection scope and findings were summarized on February 9,
1990, with those persons indicated in paragraph I above.
The inspector de-scribed the areas inspected and discussed in detail the inspection find-ings.
No dissenting comments were received from the licensee.
Proprietary material was reviewed in the course of the inspection, but is.
not incorporated into this report.
Acronyms and Initialisms Used Through This Report AFD ANS ANSI-ARO BOC CB cps DTC EFPD-EOC EPT EST Fn(z)-
ggm ICRR-IRNI ITC k(z)-
LSSS-MTC NFMS-OST P
pcm PCR ppmB-PRNI-QPTR-RCS RTP SRNI-TS VCT w(z)-
ZPPT-axial flux difference American Nuclear Society American National Standards Institute all rods out beginning of cycle boron concentration in the RCS counts per second doppler temperature coefficient effective full power days end of cycle engineering performance test engineering surveillance test enthalpy rise hot channel factor heat flux hot channel factor gallons per minute inverse countrate ratio intermediate range nuclear instrument isothermal temperature coefficient local axial power penalty function, a number
<= 1.
limiting safety system setting moderator temperature coefficient nuclear fuel monitoring system operations surveillance test fraction of rated thermal power percent millirho, a unit of reactivity plant change request parts per million boron power range nuclear instrument quadrant power tilt ratio reactor coolant system rated thermal power, the license limit source range nuclear instruments technical specifications volume control tank a cycle-dependent function that accounts for power distribution transients encountered during normal operation zero power physics tests