ML17227A369

Cycle 11 Startup Physics Testing Rept.

ML17227A369
Person / Time
Site:	Saint Lucie
Issue date:	03/25/1992
From:	Klein R, Mead W, Wunderlich E FLORIDA POWER & LIGHT CO.
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ML17227A368	List: ML17227A367 ML17227A369
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NUDOCS 9204070122
Download: ML17227A369 (18)

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9204070122 920401 PDR ADOCK 05000335 P PDR

St. Lucie Unit 1, Cycle 11 Author Walter D. Mead Y Reactor Engineering, St. Lucie Plant Reviewed ay Kle n Reactor Engineering, St. Lucie Plant Reviewed Mo sto Jimenez Reactor Support upervisor, Nuclear Fuel Approved + ~ J~+~

. Erwin J. Wunderlich Reactor Engineering Supervisor St. Lucie Plant Page 2 of 17

St. Lucie Unit 1, Cycle 11 Table of Contents ~

Section ~Pa e Title I 4 Introduction II 4 Cycle 11 Fuel Design 5 Approach to Criticality IV 5 'ero Power Physics Testing V 7 Ascension Program 'ower VI 7 Summary VII 8 References List of Fi ures F~iure No. Titles 1' '9 Cycle 11 Core Loading Pattern 10 Inverse Count Ratio Plot- Channel B 3 10 Inverse Count Ratio Plot- Channel D 4 11 RCS Boron Dilution Plot 5 12 Power Distribution- 25% Power 6 13 Power Distribution- 50% Power 7 14 Power Distribution- 100% Power List of Tables Title- '

Table No.

15'5 Cyde 11 Reload Sub-Batch ID 2 Approach to Criticality 3 16 Comparison of SNP Calculations with Measured Values 17 Comparison of'NP Calculations with Measured Values After Compensating For Lead Bank Position Page 3 of 17

St. Lucie Unit.1, Cycle 11 I

I. Introduction The purpose of this report is to provide a description of the fuel design and core load and a summary of the startup physics testing performed at St. Lucie Unit 1 following the Cycle 11 refueling. Startup physics testing verifies key core parameters are as predicted. The major parts of this'testing program are:

1) Initial Criticality following reload,

2) Zero Power Physics Testing and,

3) Power Ascension Testing.

II. C cle11 Fuel Desi n The Cycle 11 core consists entirely of fuel manufactured by Siemens Nuclear Power Corp.(SNP). The 217 fuel assemblies in the Cycle 11 core are comprised of fuel from four batches. Of these, 84 are fresh batch P assemblies consisting of 76 natural uranium axial blanket assemblies and 8 Vessel Fluence Reduction Assemblies (VFRAs); 92 are once burnt batch M, 33 are twice burnt batch L, and 8 are thrice burnt batch.K assemblies. A further breakdown of the distinct sub-batches is contained in Tablel.

This is the fifth cycle of operation utilizing gadolinia, in the form of Gd>03 as a burnable absorber, coupled with the use of natural uranium blankets at the top and bottom of each fuel assembly. The batch "P" fuel is the fourth cycle of fuel provided by SNP that uses long lower end-caps as a means of providing protection against debris fretting in the Lower End-Fitting region.

The Cycle 11 core map is represented in Figure 1. The assembly serial numbers and Control Element Assembly (CEA) serial numbers are given for each core location. The Cycle 11 reload differs from Cycle 10 in two respects:

1) The reload employs a new low-leakage design that relies on batch L fuel around the periphery, augmented with Flux Reduction Assemblies in the core flats to further reduce the fluence on reactor vessel welds for life extension purposes.

Each VFRA is constructed to the design of a standard fuel assembly with the exception of the fuel pellets loaded in each fuel rod. The VFRA design utilizes depleted uranium instead of standard reload enrichments. In addition, each of Page 4of17

St. Lucie Unit 1, Cycle 11 I

the outer four guide tube finger holes is loaded with a full-length Hafnium insert to further suppress the flux at the vessel boundary.

2) Twenty-one (21) Control Element Assemblies (CEA's) were installed to complete a comprehensive replacement program recommended by Combustion Engineering. Industry data has shown that B4C-tipped CEA's can experience cracking of the clad due to swelling of the burnable absorber within. This replacement completes the change-out process. All Type 1 CEAs in the Unit have all five-fingers of the silver-indium-cadmium design.

1'ore Following the fuel shuffle and prior to the approach to criticality, CEA drop time testing was performed. The objective of this test w'as to measure the time of insertion from the fully-withdrawn,position (UEL) to the 90% inserted position under hot, full-flow conditions. The average CEA drop time was found to.be 2.35 seconds with maximum and minimum times of 2.56 seconds and 2.16 seconds respectively. All drop times were'ithin the requirements of Technical Specifications 3.1.3.4. (i.e. less than or equal to 3.1 seconds).

III. A roach to Criticali The approach to criticality involved diluting from a non-critical boron concentration of 1602 ppm to a'predicted critical boron concentration of 1355 ppm.

The actual critical concentration was observed to be 1353 ppm. Inverse countrate ratio plots were maintained during the dilution process using wide range channels B and D. Refer to Figures 2 and 3 for data. A plot of boron concentration versus dilution time is provided in Figure 4. Table "2 summarizes the dilution rates and times as well as beginning and ending boron concentrations.'nitial criticality for St. Lucie Unit 1, Cycle 11 was achieved on December 20, 1991 at 2021 with CEA group 7 at 48 inches withdrawn and all other CEA's at the All Rods Out (ARO) position.

IV. Zero Power Ph sics Testin The major tests performed for the startup of Cycle 11 were the following:

1) Reactivity Computer Checkout

2) CEA Symmetry Test

3) All Rods Out Critical Boron Concentration Page 5 of 17

St. Lucie Unit 1, Cycle 11

4) Isothermal Temperature Coefficient Measurement

5) CEA Group Rod Worth Measurements The tests above were performed in accordance with approved procedures.

Proper operation of the Reactivity Computer is verified through the performance of two tests. In the first, reactor power is elevated sufficiently high to ensure maximum sensitivity of the instrument and at the same time preserve adequate margin to the point of adding heat. The second test ascertains response to a known value of positive or negative reactivity by measuring the values of positive or negative reactor periods that result. The results of the Reactivity Computer.

checkout were compared to the appropriate predictions supplied by the fuel vendor.

Satisfactory agreement was noted.

Verification of proper CEA Latching is confirmed through the use of a CEA Symmetry Test for those groups which contain dual CEA's (Shutdown groups A&B).

The prescribed acceptance criteria is that the reactivity measured for each dual CEA shall be within +15.0 pcm of the average reactivity measured for the entire group.

'here were no unlatched CEA's-for either shutdown group.

The All Rod's Out Critical Boron concentration was performed. The measured value was 1392.5 ppm which compared favorably with the predicted value of 1399 ppm. This was within the acceptance limits of + 100 ppm.

The measurement of the Moderator Temperature Coefficient (MTC) was performed. The MTC was determined to be 2.56 pcm/'F which fell well within the acceptance criteria of 2 2.0 pcm/'F of the design MTC 'of 1.73 pcm/'F (corrected).

This agreed favorably with the Unit 1 Technical Specification 3.1.1.4 which states the MTC shall be less positive than 7.0 pcm/'F.

The final. section of interest for low power physics testing is in the measurement of CEA Group Rod Worths. Rod worth measurements were performed using the Rod Swap methodology. This method involves exchanging the reference group (measured by Boration Dilution Technique) with each of the remaining test groups. A comparison of the measured and design CEA reactivity worths is provided in Table 3. The following acceptance criteria apply to the measurements made:

1) The measured value of each test group is within 215% or 2100 pcm of the design CEA worths, whichever is greater.

Page 6 of 17

St. Lucie Unit 1, Cycle 11

2) The measured worth of the Reference Group, and the total worth'or all the CEA groups measured is within 210% of the total design worth.

/

Test Group 2 failed to meet acceptance criteria 01 in that the measured reactivity worth of this group (816.7 pcm) exceeded the design worth (687 pcm) by 15.9%. Measurements of the remaining CEA groups were within the acceptance criteria. In addition, even though Group 2 failed the rod worth evaluation, the total worth of all CEA groups was within 10% of the total design worth.

Siemens Nuclear Power Corp. later evaluated the results of the rod worth measurements and adjusted the measured worths for differences between the ideal lead group'osition and its actual position during the measurement of the Reference Bank integral rod worth curve. These results are summarized in Table 4 and demonstrate satisfactory agreement between measured and predicted values.

V. Power Ascension Pro ram During Power Ascension; the fixed incore detector system is utilized to verify that the fuel is loaded properly and there are no abnormalities occurring in the various core parameters'(core peaking factors, LHR, and Tilt) for power plateaus at 25%, 50%, and )98% rated thermal power. Calorimetric, Nuclear, and bT power calibrations were performed at each of the plateaus prior to advancing reactor power to the next higher power level.

At 25% reactor power a fuel misload verification is performed based on information gathered from the incore instrument system. This check pointed to an assembly at c'ore location Y-14 that had a measured relative power density (RPD) in excess of the upper acceptance limit set forth in the Power Ascension procedure.

The fuel assembly in question is a hafnium Fluence Reduction Assembly (VFRA) and is the only instrumented VFRA assembly in. the core. To confirm there was no fuel assembly misloaded into core location Y-14 an analysis of the flux map was performed by the Nuclear Fuel Department of FP&L. The study concluded there was no misload involved (ref. 4).

A summary of the results of the flux maps at each power level is provided in Figures 5, 6, and 7.

Within seven days of attaining 100% power, a Hot Full Power (HFP) MTC test was performed by maintaining power constant and varying temperature. The center CEA (7-1) is inserted to permit comperisation of the resulting reactivity Page 7of17

St. Lucie Unit 1, Cycle 11 0

r changes. The HFP MTC was measured to be -4.56 pcm/'F which was within %.0 pcm/'F of the'design value of -4.90 pcm/'F. This test also verified corn'pliance 'with

. Technical Specification 3.1.1.4 which requires the measured MTC be less negative than -28.0 pcm/'F and less positive than 2.0 pcm/'F while th'ermal power is greater than 70%. The power coefficient was not measured.

VL S~ummar Compliance with the applicable Technical Specifications was satisfactory.

VII. References

1) "St. Lucie Unit 1, Cycle 11 Startup and Operations Report," EMF-91-216(P);

dated November 1991.

2) -"St. Lucie Unit 1 Technical Specifications"

3) Presentation given by Siemens Nuclear Power Corp. to FP&L, February 1992 4). Letter from W. M. Nutt to E. 7. Wunderlich: NF-92-067, dated Jan. 27, 1992, "St. Lucie Unit 1 BOC 11 - Core Location Y-14 RPD Outside Misload Verification Acceptance Limit."

Page 8 of 17

St. Lucie Unit 1, Cycle 11 Figure 1 Cycle 11 Core Loading Pattern P M K H Y X W V T S R N L J 6 F E D C B A FR07 L62 L60 FR03 a b a b 21 d c d c K02 P06 M09 P14 P11 M15 P08 K06 124 125 20 P22 M04 P34 M82 P51 M78 P31 P19

.126 127 302 123 128 , 19 P26 P42 L14 P58 M70 P55 L18 P39 Mss P27 201 122 121 120 119 204 18 KOS P18 '46 M61 P66 M47 M39 M52 P63 M65 P47 M58 P23 129 , 118 117 130 17 M08 P38 M25 L04 M19 M41 M23 L06 M64 P43 116 81, 115 16 M14 P30 L17 P70 M30 P75 P71 LO I P67 L15 P35 M11 131 114 132 113 83 112 FR02 FR05 a b a b d c PI 0 M80 P54 M49 M21 M36 M74 M75 M32 M18 M45 P59 P16 d c 14 133 111 I 110 109 108 134 13 L58 L63 P50 M72 M38 M43 P74 L12 M87 P73 M44 M37 M71 , P49 M91 12 301 107 135 106 303 LS7 "11 10 FR06 P15 136 P60 105 M46 M17 M31 M76 104 M73 103 M35 M22 M50 P53 102 P09 137 FR01

-9 a b M12 P36 L13 P68 L02 P72 M34 P76 P69 L07 L19 P29 M13 a b 8 d c d c 101 79 100 99 98 97 7 M02 P44 M28 L05 M24 M42 M20 L03 M26 M67 P37 M07 P01 96 95 85 94 K01 P24 M57 P48 M66 M51 M40 M48 P65 M62 P45 M53 P17 K07 138 92 139 P28 P40 P57 L16 P41 P25 203 91 89 88 202 P20 Mos P32 P52 M81 P33 P21 L28 140 87 304 F02 141 K08 P07 M16 P12 P13 MI0 Pos K04 142 143 FR04 L59 L61 FR08 a b a b d c r d c P13 ASSEMBLY ID 143 INSERTID Page 9 of 17

St. Lucie Unit 1, Gycle 11 FIGURE 2 WIDE RANGE CHANNEL "B" BORON DILUTION Cb 50 Cbo150 Vodo 2 Cb+50 55cpl5 00 ppm 4 Cpm polÃlw 1.0 0.9 0.9 0.8 0.8 0.7 0.7 0.6 0.6

'0.5 0.5 O

0.4 0.4 0.3 0.3 0.2 0.2 0.1 0.1 0 0 Gallons FIGURE 3 Diluted WIDE RANGE CHANNEL "D" BORON DILUTION Cb o 150 Vodo 2 Cb o50 4 pm Cb I

1.0 1.0 0.9 0.9 0.8 0.8 0.7 0.7 0.6 0.6 tt-0.5 0.5 O

0.4 0.4 0.3 0.3 0.2 0.2 0.1 0.1 0 0 Gallons Diluted Page 10 of 17

St. Lucie Unit 1, Cycle 11 FIGURE 4 RCS BORON DILUTION BORON CONCENTRATION VS. TIME 16 165 162 62 159 59 156 56 153 53 150 50 147 47 144 44 141 41 138 38 135 135 MINUTES OF DILUTION Page 11 of 17

St. Lucie Unit 1, Cycle 11 FIGURE 5 POWER DISTRIBUTION COMPARISON WITH DESIGN AT 25% POWER,,

MEASURE: (C ECOR/INPAX)

UNIT 1 SNAPSHOT ID ¹ INPAX29 POWER LEVEL 29 5%

EXPOSURE 3.50 EFPH CEAPOSITION 122" BORON CONC 1366 PPM 0.6980 DESIG N:

. 0.7020 DATASO UR C E: EMF-91-216(P) 4.0040 POWER LEVEL 25'/o p g 770 0.9000 EXPOSURE EFPH C EA POSITION 122 O.g 760 09260 BORON CONC 1399 PPM O.O010 4.0260 1.1270 1.0690 1.1210 1.1180 1.0690 1.1 240 0.0090 1 O.om 1 4.0030 1.16CO 0.9150 1.1790 1.1230 1.1560 0.9250 1.1850 1.1130 QC040 2 -0.0100 1 -0.0060 1 Q 0100 4 1.3200 'l.1490 1.1910 1.1gg 1.1450 1.3210 1.1370 12350 1.1240 1.1410 4.00IO 0.0120 4.0440 -0.0220 a 0040 1.1150 1.1020 1.2730 12240 1.1640 1.1330 1.1230 1.3180 Q9200 1~00 1.1350 4.0190 4.0210 -0.1340 2 -0.0460 > Q 0290 s 0.3810 1.1650 1.2960 1.1990 1.2230 1 0770 0.3920 1.1930 1.3150 1.2690 1.1160 4.0110 4.0280 4.0190 -00700 40390 4.0150 0.3580 1.0110 0.8610 1.1 500 0.8 MEASURED 0.3890 1.0440 0.9990, 1.1950 0.8 CESGN 4.0330 DElZA 4.03m) -O.0380 -0.0450 4.0410 s RM S DEVIATION 3.5362 0.0590 0.2360 0.0540 0.2470 Q0050 4.0110 s Page 12 of 17

St. Lucie Unit 1, Cycle 11 I

FIGURE 6 POWER DISTRIBUTION COMPARISON WITH DESIGN AT 50% POWER MEASURE: (C EGO R/INPAX) UNIT 1 SNAPSHOT ID 0 I1223110.DAT POWER LEVEL 44.7 EXPOSURE 9.0 EFPH CEA POS ITIO N ~1 BORON CONC. 1155 P.PM Q7210 DES IG N:

Q7350 DATASOUR CE: EMF-91-21 6(P) 4.0140 1 POWER LEVEL 50 10 p gg70 Q9200 EXPOSURE EFPH CEA POS ITIO N 122 1,PP80 Q9600 BORON CONC 1399 PPM 1.1410 1.0860 1.1380 1.1440 1.0980 1.1530

-0.0030 4.01 20 1 4.0150 3 1.1670 ag280 1.1910 1.1340 1.1680 0.9460 1.2070 ', 1.1360

-0.0010 2 -0.0180 4.0160 1 4.0020 4 1.3130 1.1480 1.1950 1.1090 1.3100 1.1390 " 1.2440 1.1390 1.1560 O.no 0.0090 2 4.04M 4.0300 1 4.K50 5 1.1060 1.0960 1.2660 0.7900 1.2230 1.1640 1.1100 1.1090 1.30IP 0.9250 1.2720 1.'I410 4.0040 -0.0130 3 Q0380 2 .0.1350 4.0490 i O.OR% 6 Q3800 1.1540 1.2880 1.1910 1.0740 1.2180 Q3840 1.1650 1.2890 1g480 1.1110 4.0040 3 4.0110 3 00010 2 -0.0570 40370 i 4.0140 0.3610 1.00l0 09530 1.1420 0.8 MEASURE 0.3820 1.0180 09810 1.1790 0. CESGN

-0.0210 -0.0170 2 -0.0280 4.0370 4.0370 8 ALTA 3 >

R MS DEVtAllON = aoan 0.2400 ao550 0 2500 0.0050 4.0100 Page 13 of 17

't. Lucie Unit 1, Cycle 11 in FIGURE 7 POWER DISTRIBUTION COMPARISON WITH DESIGN AT 1 00%

MEASURE: (CECOR/INPAX) UNIT 1 SNAPSHOT ID ¹ l122821 3 DAT FOWER LEVEL 9822 og, EXFOS UR E 10Q7 EFPH CEA POSITION 132 BORON CONC. 955 PPM 0.8140 0.8270 DESIG N:

-0.0130 1 DATA SOUR CE: EMF-91-216(Q 1.0610 FOWER L EVEL 1tX) op~

EXFOS URE 75'FPH 1.O74O

'EA POS ITION 135 4.0130 1 4 0330 2 BORON CO NC 914 PPM 1.1880 1.1420 1.1 950 1.1890 1.1500 12070

-0.0010 18 -0,0060 1 -0,01 8) 1.1960 0.981 0 12380 1.1750 1.1890 0.9820 12450 1.1 760 0.0070 2 4.0070 -0.0033 1.2980 1.1470 1.2500 1.1450 1 1620 1.2900 1.1430 1.2560 1.1630 1.1 840 0.0060 0.0040 -Q0060 4.01 80 i 4.003) 6 1.102) 1.0970 1.2820 Q9310 1.2670 1.1 6 1.0870 1.0870 1.2770 Q9330 1.2740 1.1 59)

Q 0150 3 0.0100 3 0.0050 -0.0020 -O.PO70 1 0.0130 6 03890 1.1260 1.2470 1.2100 1.0920 12240 03690 1.1110 1.2370 1.2140 1 1040 12420 Q0200 0.01% 0.0100 -0 0040 -0 0120 4.01 80 ~KEY 0.37G) Q967O Q8360 1.1200 Q820 MEASURED 0.3670 Q9650 Q8420 1.1470 Q861 DESGN DELTA 0.0030 -0.0060 4.0270 -0.0410 s 0.058) 0.2470 RM S DEVIATION = 13837 0.058) 0.2560 4.0010 -Q 0090 Page 14 of 17

St. Lucie Unit 1, Cycle 11 Table I Cycle 11 Reload Sub-batch ID Sub-Batch 8 of Assemb Enrich.

Kl 8 3.60 Ll 8 3.84 L2 17 3.81 L4 8 3.72 Ml 16 4.00 M2 12 3.97 .

M3 16 3.90 M4= 44 3.89 MS 4 3.87 Pl 16 3.75 P2 12 3.75 P3 40 3.75 P4 4 3.75 P5 4 3.75 P

Table 2 Approach to Criticality Dilution Rate Init. Boron Conc. Final Boron Conc. Dilution Time(min) 132 gpm 1609 ppm 1500 ppm 31 88 gpm 1500 ppm 1402 ppm 48 44 gpm 1402 ppm 1353 ppm 51 Page 15 of 17

St. Lucie Unit 1, Cycle 11 Table 3 Comparisons of SNP Calculations With Measured Values, CEA Group Worth Summary CEAGrou Measured Desi n  % Diff.

7 616.1 559 '-9.3 %

B/6 740.6 649 -12.4 %

2 816.7 687 -15.9 %

4 764.2 683 -10.6 %

1 834,2 735 -11.9 %

5/3 875.4 856 -2.2 %

A 1136.5 1166.8 -6.2%

Total 5783.7 5235.8 -9.4%

Note: Allworths in pcm

% Diff= (D/M-1)100 HZP Critical Boron Condition Measured Design(Adj) Difference (M-D)

ARO 1392.5 ppm 1399 ppm -6.5 ppm Moderator Temperature Coefficient Condition'easured Design(Adj) Difference(M-D)

ARO +2.56 pcm/'F +1.73 pcm/'F +0.69 pcm/'F Page 16 of 17

St. Lucie Unit 1, Cycle 11 Fable 4 Comparison of SNP Calculations with Measured Values After Compensating for Lead Bank Position CEAGroup Worth Summary CEA Group Adjusted Design  % Diff.

Measured cm 7 590 559 -5.24'%9.23 B/6 715 649  %

2 791 687 -13.1  %

4 738 683 -7,45  %

1 808 735 -9.03  %

5/3 850 856 0.71  %

A 1136 1066.8 -6.09  %

Total 5628 5235.8 -7.49 %.

% Diff= (D/M-1)100 Reference 3 Page 17 of 17