IR 05000259/1992014
| ML18036A679 | |
| Person / Time | |
|---|---|
| Site: | Browns Ferry  |
| Issue date: | 04/09/1992 |
| From: | Burnett P, Crlenjak R NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II) |
| To: | |
| Shared Package | |
| ML18036A678 | List: |
| References | |
| 50-259-92-14, 50-260-92-14, 50-296-92-14, NUDOCS 9205050022 | |
| Download: ML18036A679 (10) | |
Text
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UNITED STATES NUCLEAR REGULATORY COMMISSION
REGION II
101 MARIETTASTREET, N.W.
ATLANTA,GEORGIA 30323 Report Nos.:
50-259/92-14, 50-260/92-14, and 50-296/92-14 Licensee:
'ennessee Valley Authority 6N 38A Lookout Place 1101 Market Street Chattanooga, TN 37402-2801 Docket Nos.:
50-259, 50-260, and 50-296 License Nos.:
DPR-33, DPR-52, and DPR-68 Facility Name:
Browns Ferry Units 1, 2, and
Inspection Conducted:
March 30 and April 2, 1992 Inspector:
. T.
Bu nett e Signed Approved:
R.
V. Crlenj
,
ief Operational Pro ams Section Operations Bran Division of Reactor Safety Da igned SUMMARY Scope:
This routine unannounced inspection addressed the areas of surveillance of core power distribution limits, calibration of nuclear instrumentation systems, core thermal power evaluation, and reactivity management.
Results:
All tests and surveillances reviewed by the inspector were satisfactory with respect to both frequency and results.
The number of failed local power range monitors is approaching the limit for both average power range monitor applications and for rod block monitor applications (paragraph 3).
Some microfilm records of surveillances were found to be incomplete (paragraph 6).
t No violations or deviations were identified.
9205050022 920409 PDR ADOCK 05000259
REPORT DETAILS Persons Contacted Licensee Employees:
- H. Bajestani, Technical Support Manager J.
Corey, Site Radiological Control Manager
- D. Laugherty, HS Document Support
- J. Lewis, Reactor Engineering Supervisor
- P. Salas, Compliance Supervisor
- J. Scalice, Plant Manager
- J. Wallace, Compliance Engineer Other licensee employees or contractors contacted included engineering and office personnel.
NRC Resident Inspectors E. Christnot, Resident Inspector
- Attended exit interview on April 2, 1992 Acronyms and initialisms used throughout this report are defined in the final paragraph.
Surveillance of Core Power Distribution Limits (61702)
2-SI-2.1 (Revisions 4,
5, and 6),
Core Performance Data, implements the daily, with power a
percent RTP, surveillance of thermal limits required by TS 4.5. I,J,K, and L.
Selected samples of completed copies of the procedure were reviewed for the months of September 1991 to February 1992, inclusive.
All thermal limits were satisfactory and within the expected range in all cases reviewed.
In the course of the inspection, over 30 P-ls were reviewed.
With the exception of one record obtained at reduced power following a plant shutdown, the number of Base Crit Codes reported on the P-ls was small, usually zero.
This reflects care on the part of the licensee to assure that the Base distribution is regularly updated.
No violations or deviations were identified.
Calibration of Nuclear Instrumentation Systems (61705)
As discussed in Inspection Report 91-27, early in the cycle there were a
large number of failed LPRMs.
Vendor personnel recovered many of the
'PRHs by applying high voltage shocks to them.
Since that time, the number of unrecoverable failures has increased to 32 of 172 LPRHs.
Two different LPRH designs are in use, and the failure rate of one design appears to be much greater than the other.
The licensee has arranged for rapid access to
new LPRH strings should there be a plant outage of sufficient duration to permit replacement.
The licensee estimates the
minimum time to complete a mid-cycle replacement of LPRH strings would be three weeks.
Twenty-four of the forty-three strings are scheduled for replacement during the next refueling outage.
The LPRH failures to date do not appear to have a significantly adverse effect on the ability to measure core power distribution and thermal limits.
The failures do have a potential for affecting APRH operability.
APRMs receive inputs from 21 or 22 LPRHs, and the TS-allowed minimum is 14 LPRHs per APRN.
Currently, APRM E has only 16 operating LPRMs, with only two operating at level D.
(Unlike STS, Browns Ferry TS do not require a
minimum of two LPRHs per level.)
The licensee and GE are currently evaluating operation with 11 LPRMs per APRH.
The greatest impact of the LPRH failures, at this time, is on RBH operability.
For central control rods, half of the LPRNs in a RBN channel must be operable for the channel to be operable.
Thirty rods now have at least one of the two RBH channels at the operability limit.
Ten of the thirty control rods have both channels at the operability limit.
The licensee is considering proposing a
TS change to remove the requirement for RBH operability when HCPR is a 1.40 with power above 90 percent RTP or with HCPR a 1.70 with power less than 90 percent RTP.
2-SI-4. 1.B.3 (Revision 4),
Reactor Protection System LPRH Calibration, implements the surveillance requirements of TS Table 4. 1.B (item 3).
The procedure has been performed five times this operating cycle at intervals of
<1000 EFPH.
This more than minimum frequency of calibration is reflected in the absence of Base Crit Codes discussed in paragraph 2.
No violations or deviations were identified.
Core Thermal Power Evaluation (61706)
0-TI-61 (Revision 7),
Core Manual Heat Balance, is performed monthly to check the calculations made by the plant computer or when the computer is unavailable.
During Inspection Report 91-27, it was noted, for Revision 5 of the procedure, that the calculation included a
density correction for feedwater temperature differing from the nominal value.
The inspector questioned the application of this correction; since it would appear that, if such a correction were to be made, it should be as the ratio of the square roots of the densities rather than the ratio of the densities.
The licensee reviewed the bases for the calculation, and revised the procedure to perform by manual calculation the same correctibn used in plant computer program P-4, Ten-Minute Core Energy Increment.
That temperature correction adjusts both for the change in water density and for the effect of temperature on the flow nozzle calibration.
The inspector has no further questions on this subject.
No violations or deviations were identifie Reactivity Management (61707)
2-SI-4.3.C, Control Rod Scram Time Testing, was performed as required by TS for all rods prior to exceeding 40 percent RTP.
The initial cycle tests were conducted at 950 psig between July 4 and July 7, 1991.
All rods performed acceptably.
Subsequent test of twenty control rods each were conducted on October 23, 1991 and January 24, 1992.
All retested rods performed acceptably.
The TAU indicator of control rod performance was calculated for each test.
All results were negative, hence, no additional penalty was applied to the HCPR limit.
2-SI-4.3D, Reactivity Anomaly, has been performed every full power month throughout the current cycle.
The reactivity change with burnup appears to be proceeding much as predicted, and typical reactivity differences are less than half of the allowed 1 percent dK/K.
In addition to the official surveillances, the reactor engineering supervisor has been making and plo'tting weekly estimates of the reactivity difference.
These too show acceptable agreement with prediction.
No violations or deviations were identified.
Exit Interview The inspection scope and findings were summarized on April 2, 1992, with those persons indicated in paragraph 1 above.
The inspector described the areas inspected and discussed in detail the inspection findings.
No dissenting comments were received from the licensee.
Proprietary material was reviewed in the course of this inspection, but is not included within this report.
One subject discussed at length during this interview was the quality of microfilmed records of surveillances.
Hany of the procedures reviewed by the inspector required that printout from the plant computer be attached to the completed procedure.
Cognizant reviewers of the procedures assured the inspector that those printouts were attached at the time of their review.
However, in many of the microfilmed records reviewed by the inspector, the printout was missing in part or in total.
In other cases, the film of the printout was too dark to read.
Acronyms and Initialisms APRH dK/K EFPH LPRM HCPR P-1 p-4 RBH RTP SI Average Power Range Monitor Reactivity Effective Full Power Hours Local Power Range Monitor Minimum Critical Power Ratio Periodic Core Evaluation Program on the Process Computer Process Computer Program Rod Block Monitor Rated Thermal Power Surveillance Instruction
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STS TI TS Standard Technical Specifications Technical Instruction Technical Specification
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