IR 05000400/1989018
| ML18005B104 | |
| Person / Time | |
|---|---|
| Site: | Harris  |
| Issue date: | 10/05/1989 |
| From: | Belisle G, Burnett P NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II) |
| To: | |
| Shared Package | |
| ML18005B103 | List: |
| References | |
| 50-400-89-18, IEIN-89-031, IEIN-89-31, NUDOCS 8910190264 | |
| Download: ML18005B104 (7) | |
Text
~PR REC{li Op.
~4 O
Cy p
, (l p t 4p ON
+>>*<<+
Report No.:
50-400/89"18 UNITED STATES NUCLEAR REGULATORY COIVIMISSION
REGION II
101 MARIETTASTREET, N.W.
ATLANTA,G EO R G IA 30323 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:
August 28 to September 1,
1989
~ f
/
Inspector:
P.
. Burnett Date Signed Approved by:
. -J-=='.
G.
A. Belisle, Chief Test Pr'ograms Section Engineering Branch Division of Reactor Safety SUMMARY
- ir Date Signed I
Scope:
This routine, unannounced inspection addressed the core performance areas of power distribution monitoring, nuclear instrumentation calibration, control of shutdown mar'gin',
and measurement of moderator temperature coefficient at end of core life.
Results:
Continuous monitoring of core thermal power is not possible because all neces-sary inputs are not wired into the plant computer.
The licensee acknowledged'ontinuous monitoring is desirable-and is currently considering modifications to accomplish it - paragraph 3.
The correlation coefficients obtained in the excore-incore nuclear instrument correlations were poorer than those observed at other facilities.
Part of the problem appears to stem from the low currents produced in the excore nuclear instruments
- paragraph 3.
I Moderator temperature coefficient at end of life was measured only during boration, and the opportunity to make a second, confirmatory, measurement during deboration was wasted.
The.licensee made a commitment to make both measurements in future appli'cations of this test method - paragraph 5.
<){.):.i 3') j./i)l <<~.
{)(p<)Q. I( )
~ w)(~
AX)'L)) ) '*7))
).)
In December 1989, the unit.is scheduled to start its third cycle of operation with the original hafnium control rods.
This is the last cycle for which operation with these rods is justified, but no'firm commitment to replace them has been made as yet paragraph 6.
No violations, or deviations were identifie REPORT DETAILS 1.
Persons Contacted Licensee Employees
"J.
A.
"J.
M.
"J.
G.
- J.
G.
"C.
S.
W.
A.
"D L
"R.
B.
~M.
G.
Brown, Senio'r Specialist, equality Assurance Collins, Manager, Operations Garcia, Reactor Engineer Hammond, Director, Onsite Nuclear Safety Hinnant, Plant General Manager Slover, Principal Engineer, Technical Support Tibbets, Director, Regulatory Compliance Van Metre, Manager, Technical Support Wallace, Senior Specialist, Regulatory compliance Other licensee employees contacted included shift foremen, engineers, and office personnel.
Other Organizations NRC Resident Inspectors
~M.
C.
Shannon, Resident Inspector
- Attended exit interview on September 1, 1989.
Acronyms and initialisms used throughout this report are listed in the last paragraph.
'.
Core Power Distribution Monitoring (61702)
TS 4.2.2. l.d. 1 and 4.2.3.2.b require that.F (Z), and Fd
, respectively, be measured every
EFPD.
The measurements a%e accompli@ed by performance of EST-710 (Revision 6),
Hot Channel Factor Test.
Review of the tests completed in the period from October 1988 to July 1989, confirmed that the measurements had been performed with acceptable frequency and results satisfying TS 3.2.2 and 3.2.3.
No violations or deviations were identified.
3.
Nuclear Instrument Calibrations (61705)
TS 4. 3. 1. 1 and TS Table 4. 3-1, item 2a require a daily calibration of the PRNIs against reactor thermal power determined from calorimetric analy-sis.
The required measurement is accomplished by performance of OST-1004 (Revision 3),
Power Range Heat Balance Daily Interval Mode 1 (above
\\
percent Power).
Twelve completed procedures were selected for review.
All of the procedures were -completed with acceptable results.
While reviewing the procedures, the inspector observed that the licensee lacked the capability to perform continuous measurements of reactor thermal power because many of the necessary inputs are not wired into the plant comput-er.
That lack makes this facility more vulnerable to undetected overpower operation between formal PRNI recalibrations.
Experience at other facilities has shown that the radial power distribu-tion of the core can change significantly over a few hours and reduce the leakage-flux-to-power ratio.
The result has been operation in excess of 102K RTP for several hours.
The licensee was encouraged to consider the modifications necessary to provide continuous, online computer monitoring of reactor thermal power as an aid to the operators as well as a means of assuring adherence to the license limit.
At the exit interview, management acknowledged that continuous monitoring of thermal power was desirable and stated that the necessary plant modifications were under review.
The TS noted above also require an incore-excore calibration above
percent RTP every
EFPD.
That calibration had been accomplished three times in the current cycle by performance of EST-717 (Revision 3),
Incore-Excore Detector Calibration.
The frequency of performance satisfied the requirements, but the quality of the test results was not as good as observed during inspections at other facilities.
For the first test, performed at 76 percent RTP, the correlation coefficients for the assumed linear relationship between flux axial offset and current ranged from 0.835 to, 0.951.
The lower results may challenge the assumption of linearity.
Commonly, coefficients of at least 0.98 are observed for each of the eight chambers at other facilities.
In spite of the poor.results, the second test was not performed until
EFPD had elapsed.
The correlation coefficients for that test, at 98%%uo RTP, ranged form 0.913 to 0.991.
The third test, performed after another
EFPD had elapsed, yielded correlation coefficients ranging from 0.964 to 0.999.
The power level for test three was 100 percent RTP.
The inspector attempted to correlate the chamber correlation coefficients with chamber current, which is low relative to that observed at other facilities.
The inspector concluded that low chamber current contributed to the poor results, but was not the sole variable affecting the results.
Methods for increasing PRNI current were discussed with the licensee, and the licensee was provided with the names of contacts at another facility, where chamber current had been increased significantly by the addition of moderating material within the instrument carts.
No violations or deviations were identifie.
Reactivity Control (61707)
a.
Shutdown Margin TS 4. l. 1.2 b requires that the SDM be determined at least once per
hours while in modes 3,
4, or'.
The required surveillance is accomplished by p'erformance of OST-1036 (Revision 3), Shutdown Margin Calculation Modes 1-5.
Review of the completed procedures for the.
period September 12, 1988 to date revealed 61 examples of properly performed procedures.
However, records were not found for three dates for which the surveillance was required.
Those dates September 23 1988, December 16, 1988, and December 18, 1988 - were referred to the licensee to determine if the required surveillances were performed.
All three records were fouhd by a manual search by the licensee.
Predicted Critical Control Rod Positions c ~
TS 4. 1.'1. 1. 1 c requires that predicted critical control rod positions be verified to satisfy TS= 3. 1.3.6 within four hours prior to achieving criticality.
Since the initial startup following refuel-ing, the reactor has been restarted nine times.
(The last restart was on March 15, 1989.)
In each case, the EXSPACK computer program was used -both to predict the estimated critical conditions within four hours of startup and to compare the estimated and actual conditions for the actual time of startup.
The latter activity was performed, as a.quality control check on EXSPACK, which proved to'e calculating reliably.
The reactivity differences (actual condition-estimated condition)
ranged from-181 pcm to
+267 pcm.
The licensee's acceptance criterion is +500 pcm.
J Overall Core Reactivity Balance TS 4. l. 1. 1.2 requires that an overall core reactivity balance be performed every
EFPD.
, The licensee satisfies that surveillance requirement by performance of EST-700 (Revision 4),
Core Reactivity Balance, and use of the computer program FOLLOW.
In practice, the licensee enters data into FOLLOW for any day for which the thermal power has deviated less than 2 percent in the previous two days.
Hence, the calculati'on of reactivity deviation is nearly continuous.
From the first calculation on November 7, 1988, near the-beginning of cycle to June 30, 1989, the absolute difference between measured and predicted reactivities has ranged from 84 to 319 pcm with no trend evident.
The TS-allowed deviation in 1000 pcm.
EST-720, Normaliza-tion of the Boron Letdown Curve, was not required for this cycle.
No violations or deviations were identifie Measurement of Moderator Temperature Coefficient at End of Life (61708)
EST-702 (Revision 4), Moderator Temperature Coefficient -
EOL Using the Boron Method, was performed on August 9, 1989 at an RCS C
of 281 ppmB.
Only a single measurement was performed as the C
was inPreased by
ppmg.
The-112 pcm change in reactivity was co ensated by a 3.4 p
decrease in RCS average temperature and a 1.3 percent RTP decrease in power.
No attempt was made to make similar observations's the RCS was deborated back to normal operating parameters.
Thus, there was no corroboration of the measurement, which was about 5 pcm/'F less negative than predicted.
The single measurement of MTC equaled-28 pcm/ F, which satisfied the TS 4. 1. 1.3b limit of -41.5 pcm/'F and precluded the need to perform additional MTC measurements during the cycle.
The inspector discussed the measurement with the licensee's technical staff, and they agreed to revise the procedure to requi,re the MTC measure-ment during both boration and deboration, when the MTC at EOL is measured by the boron change technique.
Furthermore, they will add an acceptance criterion that the two measurements agree within 10 percent of the mean.
These procedure changes were confirmed as a
commitment by management at
'he exit interview and will be tracked as inspector followup item 50-400/89-18-01.
The licensee was also apprised of research currently being conducted to measure MTC at power using neutron noise analysis.
That technique, if developed successfully, would-not require any plant perturbations to-'erform.
No violations or deviations were identified.
6.
Followup of Previous Open Items (92701)
(Open)
Inspector followup item 50-400/88-35-01:
Review and consider methods to reduce the flux at the SRNIs.
The licensee has yet to resolve this concern.
Experience at another facility, at which the instrument carts were withdrawn into the shield cavity were discussed.
(Open)
NRC Information Notice No. 89-31:
Swelling and Cracking of Hafnium Control Rods.
Harris is equipped with the control rods addressed in the-notice and will start the third cycle of operation with them in December 1989.
The unit is currently operating under a generic JCO prepared by Mestinghouse, the rod and NSSS supplier.
The JCO justifies three eighteen-month operating cycles.
At the start of the refueling outage scheduled to begin on October 21, 1989, the licensee will perform drag tests on all control rods prior to removing the upper internals.
The procedure to perform the tests, evaluate the results, and conduct any followup testing has not been
written.
The licensee has concluded that it would not be cost effective to try to justify hafnium rod operation beyond a third cycle by additional testing.
The plant staff has recommended to the corporate staff that funds be provided to completely replace the hafnium rods at the end of the third cycle of operation.
The corporation has yet to make a decision on the recommendation.
Exit Interview (30703)
The inspection scope and findings were summarized on September 1, 1989, with those persons indicated in paragraph
above.
The inspector described the areas,. inspected and discussed in detail the inspection find-ings.
No dissenting comments were received from the licensee.
Proprie-tary material was reviewed in the course of the inspection, but is not incorporated into this report.
One commitment was agreed to by licensee management, and will be tracked as an inspector followup item.
IFI 50-400/89-18-01':
When the MTC at EOL is measured by the boron change technique, it will be measured during both boration and deboration.
Furthermore, the acceptance criterion will be that the two measurements agree within 10 percent of the mean.
Acronyms and Initialisms Used Throughout This Report ARO BOL CB
=Fd Fgz)
EFPD EOL EPT EST IFI JCO MTC NSSS OST pcm ppmB PRNI RCS RTP SDM SRNI TS all rods out beginning of life boron concentration in the RCS nuclear enthalpy rise hot channel factor heat flux hot channel factor effective full power days'nd of life engineering performance test engineering surveillance test inspector followup item
.-
justification for continued operation moderator temperature coefficient nuclear steam supply system operations surveillance test percent millirho, a unit of reactivity parts per million boron power range nuclear instrument reactor coolant system rated thermal power shutdown margin source range nuclear instrument technical specification