ML20215E929
| ML20215E929 | |
| Person / Time | |
|---|---|
| Site: | Palo Verde  |
| Issue date: | 05/23/1986 |
| From: | Peterson L LAWRENCE LIVERMORE NATIONAL LABORATORY |
| To: | |
| Shared Package | |
| ML20215E893 | List: |
| References | |
| NUDOCS 8610160024 | |
| Download: ML20215E929 (5) | |
Text
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g j'Eb ATTACHMENT 1
/S S?P p 57 0 gn Observations and Comments Initial Reactor Startup and Low Power Reactor Physics Tests Palo Verde Nuclear Generating Statios'fGyngt 2
'if NRC Region V Inspection by L. Rolf Peterson, P.E.
Nuclear Systems Safety Program Lawrence Livermore National Laboratery May 23, 1986
===.
Background===
I participated as a consultant member of the NRC Region V Inspection Team at Palo Verde Nuclear Generating Station, Unit 2 (Palo Verde 2),
on April 29 and 30, 1988.
During this inspection I reviewed the procedures and evaluated the test records of the checkout of the reactivity computer, the suberitical control element assembly (CEA) exercises and CEA withdrawal inverse count rate ratio measurementa, the approach to initial criticality, and the low power reactor physics tests.
7-The initial startup of Palo Verde 2 was conducted using Arizona Public Service Co. (APS), Palo Verde Nuclear Generating Station Manual, Procedure 72IC-2RXO2, Initial Criticality, Revision 0, dated February 4, 1956.
Initial criticality was achieved at 1448 on April 16, 1986.
Low power reactor physics tests were conducted using APS Procedure 72PY-2RX30, Low Power Physics Test, Revision 0, dated March 13, 1986.
The low power physics tests commenced on April 18, 1986, and were completed on April 21, 1986.
hkevi+.4enl gg& vvarniaaa W h Cnunt,Ea.ta natina mm MOR I reviewed Procedure 72IC-2RIO4, CEA Exercises and CEA Withdrawal So' Inverse Count Ratio, Revision 0,' dated February 7, 1986.
Thin procedure provided a comprehensive verification, while the rwsotor was subcritical, that all CEA assemblies operated according to design mo ex sequences of control rod movement.
The procedure also provided for
$a measurement of count rates on the startup range neutron detuulors and oc determination of inverse count rate. ratios (ICRRs) during CEA 3#
withdrawals to detect possible anomalics in reactivity worth of the O
CEAs and to prevent any unanticipated approach to criticality.
m I
The CEA exercises and CEA withdrawal inverse count rate ratio measurements at Palo Verde 2 were conducted April 12 and 13, 1988.
Test recordu are complete and well documented.
Two test exception reports (TERs) were generated during these measurements when the measured
m
/
. o pressurizer boron concentrations and for monitoring RCS boronometer readings during boron dilution and mixing.
The procedure called for inverse count rate ratio (ICRR or 1/M) plots versus RCS boron concentration and versus time during boron dilution and mixing tn assist in the prediction of conditions for initial criticality.
The procedure also required verification of at least one decade of nuclear instrumentation response overlap between the startup neutron detector channels and the log power safety channels during the final portions of the approach to critical.
T vaviawad the Official Tast copy of tha recorda af tha nPyrotoh to initial criticality including the ICRR plots.
These records showed that operations were performed in an orderly and safe manner in accordance with the Initial Criticality Procedure.
Boron' dilution starting the approach to initial criticality commenced at 0820 (8:20am), April 18, 1988.
Initial criticality was declhred at 14s8 (2:48pm), April 18, 1988.
The predicted RCD boron concentration for initial criticality with CEA Group 5 halfway (75") withdrawn and all other CEAs fully withdrawn was 1015 ppm (+/- 50~ ppm).
The measured RCS boron concentration at initial criticality with CEA Group 5 withdrawn 35.5" was 993 ppm.
Based upon the measured boron concentration, the corrected boron concentration for CEA Group 5 withdrawn 75" was 1004 ppm.
Thia valun was well within the moooptablo unoortainty of the prodiotod critical boron concentration.
Lag Power Physics Tests After Palo Verde 2 initial criticality was established, APS entered Procedura 72PY-2RX30, T.nw Pnwar Phynien Tant, Ravinton O.
Tenta included in this procedure were:
DulurminaLlen of Lhw power level mL Lhe threshold of sensible heat; CEA reactivity worth symmetry chechs; Reactivity worth measurement of Part Length CEA Group P; (for information only - not required)
Critical boron concentration measurements with all rods out and with CEA Groups 1, 2, 3, 4, and 5 fully inserted to their lower electrical limits (LELs);
Isothermal temperature measurement with CEA Groups 1, 2, 3, 4, and 5 fully inserted to their LELs.
Reactivity worth measurements of regulating CEA Groups 5, 4, 3, 2,
and 1 with no overlap; Reactivity worth measurements of regulating CEA Groups 5, 4,
3, 2, and 1 with overlap.
cverlap separation between two CEA groups fell slightly outside the predicted range of separation.
In the first instance, the~ measured separation between CEA Groups 5 end 4 during manuel nequential insertion was 96 inches while the predicted range of overlap was 92.5" - 95.0".
In the second instance, the measured separation beween CEA Groups 3 and 2 during withdrawal was 95.3 inches and the predicted range of overlap was 92.0" - 95.0".
In both cases the small deviation in CEA overlap during manual cequential insertion or withdrawal of the CEAs does not affect reactor safety.
It should be noted that the Technical Specifications spealfy cequence of CEA movement but do not specify separation.
An Engineering Evaluation Request (EER) was initiated to get Combustion Engineering concurrence for a wider acceptance band for CEA overlap ceparation for the two TERs described above and to accept the measured results as is.
The two TERA and the associated EER were properly reviewed by the Test Results Review Group prior to reactor startup for initial criticality.
Interim approval for Mode 2.1 entry was given on April 17, 1986.
I concur with this course of action.
Initial lCrit_ical_ity I reviewed Procedure 72IC-2RX02', Initial Criticality, Revision O.
Two uronerly anoroved Procedure Change Notices (PCNs) corrected minor discrepancies in the original Initial Criticality Procedure.
I found that the procedure, including the PCNs, was complete and incorporated good operating practices for a safe approach to initial reactor l
criticality.
l 7he initial criticality procedure included adequato precautions to t
prevent an unanticipated criticality and to ensure proper detection of j
the neutron multiplication during startup.
The procedgre establisheo l
safe initial conditions for reactor startup with a high boron concentration (greater than 1300 ppm boron).
I verified that the reactivity computer checkout had been completed and documented in accordance with Procedure 72PY-2RX31, Reactivity Computer Checkout, Revision 1, on April 13',
1980.
Startup and initial criticality was performed with the primary reactor coolant system (RCS) at 565 degrees F temperature and 2250 psia pressure.
The initial boron concentration was 1317 ppm in the RCS and 1311 ppm in the pressurizer.
All CEA groups were fully withdrawn except for CEA Group 5, which was uithdrawn to half insertion (75 inches withdrawal).
The procedure for boron dilution to approach criticality was cautious.
I It provided for periodic sampling and laboratory analysis of the RCS and
Low power physics tests were conducted at RCS temperature / pressure =
565 degrees F / 2250 psia.
I reviewed APS Procedure 72PY-2RX30, Low Power Physics Test, Revision O.
The procedure was modified by one PCN to allow installation of the reactivity computer as a test modification.
I found that the procedure was comploto and oxylicit for all physica test activities.
The procedure established prerequisites for low power physics testing that included comprehensive personnel indoctrination; pretest briefing of operations personnel; equipment availability, calibration, and configuration requirements; and special surveillance rcquirements.
Initial conditionn for antry into the proemdurn warm clearly stated.
Cpecial precautions to be observed during the procedure were provided.
I reviewed the Official Test Copy of the records of the low power physics tests.
All experiment data was analyzed by at least two people to detect errors and minimize interpretive variation.
Good records were kept of all raw data for future reference.
I believe that the data obtained was good and that the final results of data analyses were accurate.
Results of these measurements were:
MEAiiUREMENT PREDICTED VALUE MEASURED VALUE Threshold Sensible Heat approx 0.01% Power 0.01% Power CEA Symmetry
+/- 1.5 cents
+ 0.585 cents max +
Deviation maximum deviation
- 0.828 cents max -
CEA Group P Worth
-0.2344 Dk/h
-0.2724 Dh/k Critical Boron Concent.
1025 +/- 50 ppm 1012 ppm All Rods OUT Isothermal Temp. Coeff.
-1.9E-S Dh/k/degreeF
-4.3E-5 Dh/k/degreeF All Rods OUT Moderator Temp. Coeff.
-2.7E-5 Dk/k/degreeF All Rods OUT CEA Reactivity Worth Non-Overlay Insertion Group 5
-0.260% DR/k
-0.276% DR/k Group 4
-0.421% Dk/k
-0.462% Dh/k Group 3
-0.8484 Dk/k
-0.792% Dh/h Group 2
-0.994% Dk/k
-1.038% Dh/k Group 1
-1.276% Dk/k
-1.266% Dk/k
-3.799% Dh/k
~3.824% Dk/k
- $5.29
- $5.33
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~
9 HEASUREMENT PREDICTED VALUE MEASURED VALUE Critical Baron Concent.
898 +/- 50 ppm 702 ppm CEA Grps 1,2,3,4,& 5 LEL Isothammal Temp. Coeff.
=1.32E-4 DR/R/degrecF
-1.31E-4 Dk/k/degreeF CEA Grps 1,2,3,4,& 5 LEL Moderator Temp. Coeff.
-1.15E-4 Dh/k/degreeF l
)
CEA Reactivity Worth
- $5.29
- 35.38 Overinp Withdrawal In all cases the parameters measured at Palo Verde 2 conformed to credicted design valuan and ware very n.orly the name ao correspondina values measured at Palo Verde 1.
CONCLUllIQ)[3, I found that Arizona Public Service had adequate and complete procedures in place tu safely conduct the suberitical CEA exercises and inverse count rate ratios during CEA withdrawals, the startup to initial driticality, and the low power physics tests at Palo Verde Nuclear Generating Station, Unit 2.
I reviewed the data acquisition and analysis records of the cuberitical CEA exercises and inverse count rate ratio measurements, the initial criticality startup, and the low power physics tests i
conducted at Palo Verde 2.
Accurate data was obtained for all pre-startup, startup, and low power physics test evolutions.
I concur eith Lhu LuvL data analysas and 6V61uationa made by Arizona Public Service and' Combustion Engineering personnel.
No deviations from expected nuclear design characteristics that would l
cdversely affect safety of operations of paln Verde 2 were observed during the pre-startup subcritical CEA exercises, the initial reactor
- ctartup, and the low power physics test program.
Wh:: =-
L. Rolf Peterson, P.E.
Nuclear Systems Safety Program Lawrence Livermore National Laboratory