IR 05000255/1991003
| ML18057A804 | |
| Person / Time | |
|---|---|
| Site: | Palisades  |
| Issue date: | 03/11/1991 |
| From: | Langstaff R, Lougheed V, Vanderniet C NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| To: | |
| Shared Package | |
| ML18057A803 | List: |
| References | |
| 50-255-91-03, 50-255-91-3, NUDOCS 9103210042 | |
| Download: ML18057A804 (13) | |
Text
U.S. NUCLEAR REGULATORY COMMISSION
REGION III
Report No. 50-255/91003(DRS)
Docket No. 50-255 License No.. DPR-20 Licensee:
Consumers Power Company*
1945 West Parnell Road Jackson, Michigan 49201 Facility Name:
Palisades Nuclear Generating Plant.*
Inspection At:
Palisades Site, Covert, Michigan*
Inspection conducted:
February 1ithrough March 1, 1991 Inspectors:
r&,'L.1-Ji R.' A. ~angstf Approved By:
Inspection summary Inspection on February 11 through March l, 1991 (Report No. 50-255/91003(DRS).
Dat'e I Dfit I
Areas Inspected:
Routine announc.ed safety inspection _by regional based inspectors of the -1icens.ee' s containment integrated leak rate test (CILRT) and local leak rate test (LLRT) progra Results:
No violations or deviations were identifie Inspection modules used during this inspection were 61720, 70307, 70313, 70323, and 9370 The licensee successfully met the acceptance criteria for the CILR Licensee strengths were apparent in the preparations for and conduct of the tes No licensee weaknesses were identified.
9103210042 910311 PDR ADOCK 05000255 Q
- DETAILS.
Persons Contacted Consumers Power
.*'
- R. Brzezinski, Instrumentation and Control Superintendent
- H. Esch, Staff Engineer
- C. Hillman, Plant Licensing.Engineer
- L. Keanaga, Health Physics Superintendent
- D. Kennedy, Instrumentation and Control Engineer
- J. Kueman, Licensing Administrator
- J. Lewis, Steam Generator Replacement Project
- R. Orosz,. Engineering and Maintenance Manager.
- T. Palmisado, Administration and Planning Manager
- J. Petro, Quality Engineering Section Head
- G. Slade, Gen~ral Plant Manager
- K. Toner, Projects Superintendent
- R. Vanwagner,* Inservice Inspection Section Head
- R. Vincent, Plant Safety Engineer
- T. Watson, Inservice Inspection, ILRT Test Director
- J. Werner, SGRP, Quality Assurance Superintendent U.S. NRC J. Heller, Senior.Resident Inspector B. Holian, Project Manager,: Nuclear Reactor Regulation J. Hopkins, Acting Resident Inspector
- D. Passehl, Resident Inspector, D. c. Cook
- Attended exit on March 1; 199 The inspectors also intenriewed other licensee employees during the course of the inspectio *. Licensee Action on Previously Identified Findings (93702) (Closed) Unresolved Item 50-255/88019-01 "Testing of Steam Generator Manway Cover":
The licensee previously tested its steam generator manway covers under its local leak rate test (LLRT) progra This test was performed by imposing a vacuum on the steam generators.*
The new steam generators, installed during the 1990-91 refueling cycle, no longer have this testing capabilit However, recent guidance from the Office of Nuclear Reactor Regulation (NRR) indicated that it was acceptable for the covers to be removed from the,
LLRT program, providing that the steam lines were vented during the containment integrated leak rate test*
(CILRT).
The NRR guidance had not ~een provided by the time that the licensee performed its CILRT; however, the inspectors specifically reviewed the licensee's valve lineups for the main steam lines and found it
- acceptable for this tes Based upon the NRR guidance, which is provided as Enclosure 2, this item is considered close (Closed) Unresolved Item 50-255/88019-02 "Local Leak Rate Testing of Instrument Air*Penetrations":
During the 1990-91 refueling *o~tage, the licensee performed a LLRT on the instrument air containment isolation valve The inspectors reviewed the results of these LLRTs and found them acceptabl The licensee has committed to perform a review of all containment penetrations, determine the Appendix J testing requirements for each penetration and submit this information to NRR in the form of an amendment to the Updated Safety Analysis Report (USAR)._ Based upon the licensee's commitment, this item is. considered close (Closed) Unresolved Item 50-255/88019-03 "Local Leak Rate Tests Not Performed at Pt": *The licensee performed a full pressure CILRT during the 1990-91.
refueling outag This eliminated the need to perform local tests at a reduced pressure during the outag The inspectors discussed with the licensee its plans for future CILRTs, and the requirement to perform LLRTs*
at both Pa (per section III.C.2 of 10 CFR Part 50, Appendix J) and at Pt (per section III.A.5. (b)1 of 10 CFR Part 50, Appendix-J) if a reduced pressure CILRT was again performe At the time of the inspection, the licensee.did not have.firm plans to run future reduced pressure CILRT Therefore, this item is considered close.(Closed) Licensee Event Report 90-008 "Containment Nitrogen Supply Check Valve Leakage Results in Cumulative Local Leak Rate in Excess of 0.6 Lal":
During an April 1990 LLRT on the Nitrogen line, the penetration could not be pressurize The licensee identified the leakage as corning from the inner containment isolation valv The piston of this valve was found to be stuck on some machining marks on the valve bor These marks were attributed to original valve manufacturin During root cause investigation, the licensee found that the valve piston stuck only intermittently, providing an explaination as to how the valve had previously passed LLRT The licensee remachined the bore, and the valve successfully passed the LLR In October 1990, the valve again had higher then normal leakag At that time, the valve was replaced with a different design valv The inspectors had no problem with the licensee's corrective action *
e.
(Closed) Licensee Event Report 91~004 "Containment -
Emergericy Airlodk.Leakage Results in Cumulative Local LeakRate in.Excess of Technical Specification Limits":
The licensee experiericed excessive leakage around the gasket 6n the viewing port of the-inner emergency airlock doo Further review by the licensee indicated that this gasket had never been replaced_ or otherwise maintaine The licensee was in the p-rocess of*
establishing a preventative maintenance program for future outage The inspectors also reviewed other LLRT penetrations which had excessive leakage~ and noted that the licensee performed appropriate corrective actions~
The licensee appeared to be implementing an effe9tive preventative maintenance program*in that no repeat failures were noted over the last three years of LLRT performance.
Containment Integrated Leak Rate Test Procedure Review (70307).
.. Surveillance Procedure Review The inspectors reviewed technical specifications surveillance procedure, RT-36, "Containment Integrated Leak Rate Test," Revision 15, dated January 31, 1991, relative to the requirements of 10 CFR Part 50 Appendi~ J, ANSI N45.5-1972, and the licensee's Technical Specification This procedure was also compared for consistency (as needec;t) with the structural *integrity test procedure, 20557-SI In addition, the inspectors revie~ed the valve lineups in the procedure to ensure that the licensee was properly venting and draining systems as required by Appendix The inspectors did not identify any problems with the CILRT procedur Clarifications to Appendix J As during previous inspections, the inspectors discussed with the licensee various clarifications to the requirements of Appendix J~
The licensee was given a complete list of clarifications by the inspector The following partial list contains only those clarifications which were not previously provided in inspection reports, or those which, while previously provided, were revised since the last inspectio (1)
The Type A test length.must be 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> or longer to use the mass point method of data reductio If tests of less than 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> are planned, the-Bechtel Topical Report, BN-TOP-1, must be followed
(2)
in its entirety, except for any*section which conflicts with Appendix.J or Technical Specifications requirement For* either methodology, the accep:tance criteria is that the.
measured leakage rate at the 95% upper confidence limit must be less than 75% *of the maximum allowable leakage rate for the pressure at whic~
- the test was performe *
Periodic Type A, B, and c*tests must include the as-found results as well as the as-lef If Type B and C te.sts are conducted prior to a*. Type A test, the as-found condition of the containment must be calculated by adding.any improvements in leakage rates, which are the results of repairs and/or adjustments (R/A), to the Type A test results using the "minimum pathway leakage" methodolog This methodology is ciefined as the minimum leakage value that can be quantified through a penetratl.on leakage path (e.g.:
the smallest leakage through two valves in series.)
This assumes no single active failure of the redundant valv To calculate the minimum pathway leakage:
.
.
(a)
In the case where individual leakage rates are assigned to two valves in ~eries (both before and after repairs and/or adjustments),
the minimum pathway leakage would simply be the smaller of the two valves' leakage rate (b)
In the case where a leakage rate is obtained by pressurizing between two isolation valves and the individual valve's leakage rates are not quantified, the as-found and the as-left minimum pathway leakage for each valve would be 50% of the measured leakage rate, if both valves are repaire (c)
In the case where a leakage rate is obtained by pressurizing between two isolation valves and only one valve is repaired, the as-found minimum pathway leakage rate would.be either the final measured leakage rate, or one half of the originally measured leakage, whichever is les However, in either case, the as-left minimum pathway leakage rate is zer (d)
In the cases where a leakage rate is determined by pressurizing among three or more isolation valves, appropriate guidance
(3)
shall be provided.such that the calcu.lated minimum pathway leakage, for the penetration
- and valves repaired, can be conservatively*
establishe As.an alternative, maximum pathway leakages may be use Whenever penetration configurations during a CILRT deviate from the ideal, the results of the *LLRT for penetrations must be added as a penalty to the CILRT results at the 95% upper confidence leve This penetration leakage penalty is determined using the "minimum pathway leakage" methodolog Additionally, any increase in containment sump,
.fuel pool, *reactor water, or suppression pool levels during the course of the CILRT, must be taken as a penalty to the CILRT result If penalties exist, they must be added (subtraction
- is never permitted) to the upper.confidence level of the CILRT result (4)
For the supplemental test, the size of the superimposed leakage rate must be between 0.75 and 1.25 times the maximum allowable leakage rate (La).
The higher the value, the more accurate*the measuremen The supplemental test must be of sufficient duration to demonstrate the accuracy 0£ the test~
The results are expected to stabilize within the acceptance criteria tolerance band,
-rather than the results merely ending within the ban Whenever the BN-TOP-1 methodology is being used, the length of the supplemental test cannot be less than approximately one-half of the length of the CILRT..
(5)
During a CILRT,. it may become necessary to reject or delete specific data sensors, data points due to drifting of erroneous sensors, or data outlier Data rejection criteria should be developed and used so that there is consistent technical basis for data rejectio One example of an acceptable method for data outliers is described in an Appendix to ANSI/ANS 56.8-198 Sensor data rejection *criteria should be plant-specific and.based upon a
~ensor's trend relative to the average scatter, slope, and/or absolute output of the senso (6)
An acceptable method for determining if the sum of Type B and C t*ests exceeds the O. 60 La of Appendix J limits, is.to utilize thi: "maximum pathway leakage" methodolog This methodology is defined as the maximum leakage value that can be
(7)
(8)
(9)
q\\iantif ied through a penetration leakage path (e.g~ the lar~er, not total, leakage of two valves in series~)* This assumes a single active-failure*
t6 the better of twd leakage barriers in series when performing Type B or C tests..
Whenever a valve is replaced, repaired, or repacked during an outage for whi~h Type A, B, and/or c surveillance testing was scheduled, local leak rate testing for the as-found, as well as the as-left condition, must be performed on that penetratio In the* cases of a replaced valve, the as-found test can be waived, except during outages when a Type A test is scheduled, provided no other containment isolation valve of similar design exists at any nuclear site owned by the same utility~
All air sources inside containment during a CILRT must be vented to atmosphere during the tes If they are not vented, then they must be.monitore In the latter case, the CILRT penalty *needs tq take into account the readability and sensitivity of the monitoring instrumentatio If the air sources are neither ve.nted nor monitored, the penalty added to the CILRT results must assume that the air source pressure dropped from its design pressure to the test pressure during the course of the tes When determining the results of the Type B and c tests, the minimum readability, accuracy, and sensitivity of the instrumentation need to be takeri into accoun No leakage rates should be reported as zero, but rather reported as the minimum discernable valu.
Containment Integrated Leak Rate Test Witnessing. (70313) Calibration Data The inspectors reviewed the calibration data and determined that all the instruments used in the CILRT had been properly calibrated and that the correct weighting factors had been placed in the computer program as require The following instrumentation was used throughout the test:
- *
~
Temperature Humidity Pressure
- Flow* Witness of Test Quantity
10
.1
The.inspectors witnessed the final containmen pressurization (the containment was depressurized and held at a reduced pressure for 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> following pressurization to the full structural integrity. test pressure of 77.95 psia), temperature stabiliazation, and the beginning of the CILR The inspectors noted that test prerequisites were met and that the
appropriate revision to the test procedure was followed by test personne Valve lineups for various systems were verified to ensure that no fluid.could enter the containment atmosphere and that proper venting and draining w~s provide The following systems were the only systems not verified to be in their required test positions:
System/Penetration.
CILRT.Fill Line/ Penetration MZ-27:
valve lineups verified through ability to pressurize containment. *
Containment Spray Discharge/ Penetrations MZ-30, 31:
water filled lin Containment Sump Level Instrument Lines/.Penetrations MZ-17, 52A, 52B, 56:
instruments verified to be working during CILR Instrument Air/Penetration 65:
not verifie All other systems had the entire inside containment portion and the majority of the outside containment valve lineups verifie No violations or deviations were identifie.
Test Results Evaluation (70323) Review of Licensee's Computer Program for Calculation of Leakage Rates The inspectors reviewed-the licensee's results and independently calculated containment masses and leakage
- * *
ra~es, using the.licerisee's.individual sensor data.
Minor discrepancies were noted between the licensee's program and the program used by.the inspector These discrepancies were discussed with* the licensee.'
The inspectors determined. that these discrepancies were attributable to round--off errors, among other.{tern The final :results from both the in~pectors' program and the licensee's program were acceptabl CILRT Data Evaluation A 14.75 hour8.680556e-4 days <br />0.0208 hours <br />1.240079e-4 weeks <br />2.85375e-5 months <br /> CILRT was performed on February 15, 1991 at a test pressure of 69.7 psia following satisfactory pressurization to the full structural integrity test pressure of 7.7. 95 psia, a partial depressurization hold period, repressurization, and the required temperature stabilization perio Data was collected every 15*
minute The inspectors independently evaluated leak rate data using total time (BN-TOP-1) formulas to verify.the licensee's calculations of the leak rate.and instrument performanc As noted above,- there were minor discrepancies between the inspectors' and licensee's methodologies for calculating masse Once these were taken into account, there was excellent agreement between the_ inspectors' and licensee's results as indicated by the following summary (units
. are in weight percent per day).
Measurement Measured leak rate during CILRT. (Lam)
Lam at 95 percent Upper Conf idenc? Level (UCL)
Licensee Inspectors 0.025 0.025 0.070 0.070 The Appendix J acceptance criteria is th_at Lam, at the 95% upper confidence level (UCL), be less than 0.75 La (0.075 wt%/day).
The test met this criteri Supplemental Test Data Evaluation After satisfactory completion of the CILRT, a known leakage rate of 5.47 scfm, equivalent to 0.101 wt%/day was induce The licensee commenced the supplemental test following the one hour stabilization period required by BN-TOP-Data was collected and analyzed
- by the licensee every 15 minute The licensee
-
concluded ttie test after 7.5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br />, following a test period approximately one-half the hold test in length, as required by BN-TOP-The inspectors independently
calculated the supplemental test imposed leakage rate and test results, as noted belo All data units are
.in weight percent per day (wt%/day) *
Measurement Measured leakage rate (Le)
during svpplemental test Induced Leakage Rate (Lo) *
Results from main test (Lam)
Le -
(Lo + Lam)
Licensee Inspectors 0.122 0.122 0.101 0.101 0.025 0.025-0.004-0.004 The Appendix J acceptance criteria is that the value of
[Le -
(Lo+ Lam)).be within a band of+ 25 % *of La.
. For Palisades, this results in ah acceptance criteria of -0.025 < [Le -
(Lo+ Lam)] < 0.02 The supplemental test results fell.within this ban CILRT Volume Change Corrections At the completion of the CILRT and the supplemental test., the licensee is normally required to make
.corrections to the calculated Lam at the* 95% UCL due to changes in volume of various water sources inside containmen The inspectors reviewed the licensee's test log and noted that no water source volume changes were experienced during the tes Therefore, no.
corrections for this factor were necessar CILRT Valve Lineup Penalties Due* to valve configurations which deviated from the ideal penetration valve lineups for the CILRT, the results of LLRTs for such penetrations must be added as a penalty to Lam at the 95% UCL, per Appendix The licensee had the following penetrations in a configuration which differed from that which.would be experienced following an accident (Leakage rates in units of standard cubic centimeters per minute (SCCM)):
System/ Penetration Component Cooling Water/ Penetration MZ-15 Containment Pressure Instrumentation/
Penetration MZ-17
Leakage 1.1
f.*
Letdown/ Penetration MZ-36 Controlled BJ.,eedoff/ Penetration MZ-44 Containment Isolation & Safety Injection Signal/ Penetration:MZ-48 Containment sump Drain/ Penetration MZ-52 ILRT Instrument Line/ Penetration MZ-66 Total Leakage 155~2 16 a*. 1..7 37 Addition of the as-left minimum pathway LLRT result for these non-vented penetrations add~d a *peri~lty of 37 SCCM to the 95% UCL limi This ieakage was equivalent to 0.0002 wt%/day, which was negligibl As-Found Condition of Containment The as-found condition is the condition of the containment at.the beginning of the outage prior to any repairs or adjustments to the containment boundar This is normally calculated by reviewing the summary of the LLRTs and calculating the amount of leakage rate improvement due to repairs or adjustments using the minimum pathway methodolog This assumes that no major changes to the containment structure were made, but that all leakage improvements were due to penetrat~on repairs or adjustment However, during this outage, the licensee cut a hole through the. primary containment structure in order to allow repl"acement of the steam generator Thus, no correlation could be established between the pre-and post-modification leakage rate Theref.ore, this CILRT was considered to be a pre-operational test to show that the repairs to the containment adequately met the Technical Specification leakage requirements, rather than the performance of a periodic CILR In regard to the determination that this CILRT constituted a pre-operational test of the containment boundary, the inspectors discu.ssed with the licensee *
the need to rebaseline the reduced pressure test leakage rate data~
The licensee did not wish to include a baseline reduced pressure test during this refueling outag It committed, however, either to run
, **
- .....
a baseline test per 10 CFR Part 50 Appendix J Section III.A.4.a~l, or to submit sufficient information to NRR to show that.a new baseline was unnecessary, prior to performance of a reduced pressure tes No violations or deviations.were identifie.
Review of Local Leak Rate Test Results (61720)
a. -
b..
Review of Local Leak Rate Procedures The inspectors reviewed the licens~e's LLRT procedure The inspectors noted that the licensee had one main procedure, R0-32, "Local Leak Rate Test Main procedure", Revision 25 dated July 31, 1990. *This procedure maintained the as-found and as-left totals of LLRTs completed under individual procedure The inspectors also reviewed a number of individual procedures, which were identified by R0-32 and an additional suffix showing the penetration numbe The licensee used the pressure decay method to perform LLRT The inspectors noted that the licensee pressurized the penetrations to approximately 10 pounds above Pa (55 psig), and then allowed the pressure to decay to approximately P The licensee stated that this was to ensure that all tests were performed at n0 less than P The inspectors reviewed a number of individual test results,. and no problems were
- identifie Witne~sing of Local Leak Rate Tests The inspector*s attempted to witness the performance of a LLRT on the personnel airlock (Penetration MZ-19)
following mainienance to establish the interlock function between the two door During the stabilization period, the licensee noti~ed moist~re forming on the viewing por This was attributed to condensation due to eithe~ moisture in the pressurization air or due to heatup of the airlock temperatures due to rate of pressurization.* At the time of the.exit, the licensee was depressurizing the airlock in order to remove the ~oistur A successful test was run on March 1, 19,91, with the final.results reviewed by the resident inspector No violations or deviations were identified.
- 7 *
Exit Interview The inspectors met with licensee r~presentatives (d~hoted in section 1) throughout the.inspectio An exit meeting was held prior to leaving the site on Marc.h 1, 199 The inspectors summarized the scope and findings of the inspectio The inspectors also discussed the likely informational*content of the inspection report with regards to documents or processes reviewed by the inspectors during the inspectio The licensee did not identify any such
- aocuments or processes as proprietary *
13