ML20206G166

Rev to Proposed Tech Specs Reflecting Actual End of Cycle 7 Burnup of 13,580 Mwd/Mtu

ML20206G166
Person / Time
Site:	Calvert Cliffs
Issue date:	04/07/1987
From:	BALTIMORE GAS & ELECTRIC CO.
To:
Shared Package
ML20206E122	List: ML20206E117 ML20206G166
References
NUDOCS 8704140466
Download: ML20206G166 (9)

Text

,24-57a(86H2)/cp-3

1.0 INTRODUCTION

AND

SUMMARY

This. report provides an evaluation of design and perfomance for the operation of Calvert Cliffs Unit 2 during its eighth fuel cycle, at full rated power of 2700 Wt. All planned operating conditions remain the same as those for Cycle 7. However, Cycle 8 will be the first "24-month cycle" at Calvert Cliffs. It will also be the first Calvert Cliffs cycle to use a low-leakage fuel management pattern.

The core will consist of 129 presently operating Batch J and H assemblies and 88 fresh Batch K assemblies.

Plant operating requirements have created a need for flexibility in the Cycle 7 temination point. This need has been met by using a Cycle 7 window ranging from 11.300 WD/T to 13,700 WD/T in the l Cycle 8 analyses. However, subsequent to the completion of most of the Cycle 8 analyses, an agreement was reached between BG&E and the NRC concerning a proposed Technical Specification change, which restricts the Cycle 8 MTC at HFP, equilibrium Xe conditions to negative values (Reference 1). To satisfy this requirement it was l necessary that the Cycle 7 burnup be at least 12,000 WO/T. This restriction has been met by the actual Cycle 7 shutdown burnup of 13,580 WD/T. However, this document continues to cite 11.300 W O/T as the early Cycle 7 shutdown point to assure consistency with the burnup range used in the analyses.

In perfoming analyses of design basis events, detemining limiting safety settings and establishing limiting conditions for operation, limiting values of key parameters were chosen to assure that expected Cycle 8 cnnditions would be enveloped, provided the Cycle 7 termination point falls within the above discussed cycle burnup range used in the analyses. The analysis presented herein will accommodate a Cycle 8 length which varies from 1g,800 to 21,500 l MWD /T, depending upon the Cycle 7 shutdown burnup, including a coastdown in inlet temperature to 537'F and a coastdown in power to approximately 75%.

The evaluations of the reload core characteristics have been conducted with respect to the Calvert Cliffs Unit 2 Cycle 7 safety analysis described in Reference 2. Unit 2 Cycle 7 will hereafter be referred to as the " reference cycle" in this report, unless otherwise noted. This is the appropriate reference cycle because its design / safety basis is the one most recently reported to the NRC.

Specific core differences have been accounted for in the present ,

analysis. In all cases, it has been concluded that either the reference cycle analyses envelope the new conditions or the revised analyses presented herein continue to show acceptable results.

Where dictated by variations from the reference cycle, proposed '

. modifications to the existing plant Technical Specifications

are provided and are justified by the analyses discussed herein.

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24-57a(86H2)/cp-4 The Cycle 8 analyses used the same methodology as the reference l cycle in all areas except three. First, . the large break LOCA analysis (Section 8.1) used the amended C-E large break evaluation model presented in Reference 3 and recently approved by the NRC in Reference 4. Second, thennel performance data (Section 4.3) was i generated the FATES using3 fuel FATES 38model evaluation (Reference 5) (which Reference 6). is aFATES revised version of 3B has received interim NRC approval (Reference 7). Third, fine mesh pin-by-pin data was calculated by the MC Ccde (Reference 8) in place of PDQ.

The performance of Combustion Engineering 14x14 fuel at extended burnup is discussed in Reference 9, which was approved in Reference

10. For Cycle 8 the batch average discharge will be considerably less than the 45,000 WD/T criteritr. of that reference, but the burnup of approximately 0.3% of the fuel pins will be above the l 52,000 WD/T point discussed in Reference 9, if Cycle 7 and 8 are operated to their maximum burnups. However, since all Cycle 8 analyses address fuel exposure explicitly and the power levels of the few high burnup pins are low, the safety analyses documented herein are appropriate and valid for Cycle 8. Futhermore, the maximum burnup (approximately 54,300 W D/T) is well below the- l burnups which have been or are projected to be achieved in lead assembly demonstrations at Calvert Cliffs (approximately 64,000 WD/T). '

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24-57a(86H2)/cp-5 2.0 OPERATING HISTORY OF THE PREVIOUS CYCLE Calvert Cliffa Unit 2 has just completed its seventh fuel cycle l utilizing Batch J. H. G. E and D fuel assemblies. Ccivert Cliffs Unit 2 Cycle 7 began operation on December 8, 1985 and reached full power on December 16, 1985. The Cycle 7 startup testing was reported to the NRC in Reference 1. Cycle 7 terminated operation on March 14,1987 with a Cycle 7 burnup 13,580 MWD /T. The reactor operated throughout the cycle with the core reactivity, power distributions and peaking factors closely following the calculated predictions.

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3.0 GENERAL DESCRIPTION The Cycle 8 core will consist of the number and types of assemblies j and fuel batches as described in Table 3-1. The primary change to the core in Cycle 8 will be the switch from 18-month conventional fuel management to 24-month low-leakage fuel management. This change will entail the removal of 881rradiated assemblies (3 Batch H*, 48 Batch G. 28 Batch 6/, 8 Batch E and 1 Batch D assemblies) and their replacement with 88 fresh assemblies at 4.08 wtX U-235 enrichment (16 unshimmed Batch K assemblies 44 8-shimmed Batch K/ assemblies and 28 12-shimmed Batch K* assemblies).

Figure 3-1 shows the fuel management pattern to be employed in Cycle

8. Figure 3-2 shows the locations of the fuel and poison pins within the fresh K* and K/ shimmed assemblies. This fuel '

management pattern will accommodate Cycle 7 termination burnups from 11,300 WD/T to 13,700 WD/T. l The Cycle 8 core loading pattern is 90* rotationally symmetric. ,

That is, if one quadrant of the core were rotated 90* into its neighboring quadrant, each assembly would be aligned with a similar assembly. This similarity includes batch type, number of fuel rods, initial enrichment and burnup.

Figure 3-3 shows the beginning of Cycle 8 assembly burnup distribution for a Cycle 7 termination burnup of 11,300 WD/T. The '

initial enrichment of the fuel assemblies is also shown in Figure .

3-3. Figure 3-4 shows the end of Cycle 8 assembly burnup  ;

distribution. The end of Cycle 8 core average exposure is '

approximately 32,800 WD/T and the average discharge exposure is approximately 41,200 WO/T. The end of cycle burnups are based on a Cycle 7 length of 13,700 WD/T and a Cycle 8 length of 19,800 WO/T.

3.1 PROTOTYPE CEA The PROTOTYPE CEA is described in Reference 1. Cycle 3 was the i first cycle of irradiation for this CEA. During the E0C-4 and E0C-5 l outages this' CEA was examined, as described in References 2 and 3 I respectively. This PROTOTYPE CEA was utilized in the center core l position from Cycles 3 through 6 and then shifted to a new position j for Cycle 7. '

3.2 CENTER CEA COMPOSITION The composition of the center CEA, which is part of the lead bank (Bank 5), is being changed for Cycle 8. This modification is being made to support the change from 18-month conventional fuel management to 24-month low-leakage fuel management for Cycle 8.

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TABLE 3-1 CALVERT CLIFFS UNIT 2 CYCLE 8 CORE LOADING Total Initial Number Total Initial Poison Poison of Poison Number Assembly Number of Enrichment Batch p p (70f0g) Rods Per ng and Non-Fuel of Fuel Designation Assemblies (wt% U-235) BOC8 EOC8 Assembly leag/ inch)

(psB Rods Rods K 16 4.08 0 17,100 0 0 0 2816 K* 28 4.08 0 24,300 12 .036 336 4592 K/ 44 4.08 0 24,300 8 .036 352 7392 J(1) 40 4.05 9,800 33,400 0 0 0 7040 J*(1) 20 3.40 14.100 37,000 0 0 0 3520 H(1J 48 4.05 24,800 41,400 0 0 0 8448 H*(1) 21 3.40 28,000 47,300 0 0 0 36 %

Y 11,500 32,800 688 37,504

" T;tal 217 (1) Carried over from Cycle 7 to Cycle 8 of Unit 2.

(2) Cycle 7 burnup of 11,300 fedD/T (3) Cycle 7 burnup of 13,700 pel0/T and Cycle 8 burnup of 19,800 pelD/T l

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t H 2 K 38,400 16,600 3 H 4 K 5 J 6 K' 7 J 37,400 17,600 20,600 22,500 34,100 ,

9 H 9 K/ 10 J 11 K/ 12 H 13 J' 38,200 20,900 34,300 25,500 45,500 M ,300 14 H 15 K/ 16 J 17 K* IS H* 19 K/ 20 J' f 38,100 21,100 34,000 25,500 47,700 25,000 37,400 l 21 M 22 K/ 23 J 24 J 25 M* 26 K/ 27 J' 20 K*

37,400 20,900 34,000 35,000 47,200 25,100 38,000 26,100 ,

29 K 30 J 31 K' 32 H+ 33 K' 34 H 35 K/ 36 H*

17,600 34,300 25,500 46,500 24,200 45,500 25,500 40,100 37 J 34 K/ 39 H+ 40 K/ 41 H 42 J 43 H 44 J 45 28,700 25,600 47,700 25,200 45,500 H 35,900 44,000 34,700 38,400 44 K' 47 H 44 K/ 49 J' 50 K/ 51 M 52 K+ 53 J* '

54 22,600 4 ,600 25,900 30,000 K 25,600 M ,200 23,900 35,400 16,600 55 J 56 J' 57 J' 54 K' 59 H+ 60 J 61 J' 42 H+

34,100 36,300 37,400 26,100 48,100 34,700 35,400 44,000 toc 7=13,700 MWD /7 (Oce=19,000 MWO/T SALTIMORE GAS A ELECTRIC Co. CALVERT CLIFFS UNIT 2 CYCLE 8 FIGURE CALVERT CLIFFS ASSEMBLY AVERAGE BURNUP AT E0C (MWD /T) 3-4 NUCLEAR POWER PLANT 3-7

- 24-57a(86H2)/cp-11 5.0 NUCLEAR DESIGN 5.1 PHYSICS CHARACTERISTICS

5.1.1 Fuel Management The Cycle 8 fuel management employs a low-leakage pattern as described in Section 3, Figure 3-1. The fresh Batch K fuel is comprised of three sets of assemblies, all having the same enrichment of 4.08 wt". U-235 but each containing a unique number of shims in order to minimize radial power peaking. There are 16 unshimmed assemblies, 44 assemblies with 8 shims and 28 assemblies with 12 shims. With this loading, the Cycle 8 burnup capacity for l full power operation is expected to be between 18,900 MWD /T and l 20,400 MWD /T, depending on the final Cycle 7 termination point. The l Cycle 8 core characteristics have been examined for Cycle 7 tenninations between 11,300 and 13,700 MWD /T and limiting values l l established for the safety analyses. The loading pattern (see l Section 3) is applicable to any Cycle 7 termination point between the stated extremes.

l The data presented in Section 5.0 was evaluated relative to the l change in the maximum Cycle 7 shutdown burnup from 13,300 to 13,700 MWD /T. The results of that evaluation showed only minor changes to the data presented in the tables and figures of this section.

Consequently, since the data previously transmitted continues to remain representative of expected core behavior, it was not deemed necessary to revise the data in the tables and figures of Section l 5.0.

Physics characteristics including reactivity coefficients for Cycle 8the are reference listed in cycle Table(Reference 5-1 along )with the corresponding

1. Please note that thevalues valuesfrom of l parameters actually employed in safety analyses are different from those displayed in Table 5-1 and are typically chosen to conservatively bound predicted values with accomodation for appropriate uncertainties and allowances.

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! Table 5-2 presents a sumary of CEA shutdown worths and reactivity allowances for the end of Cycle 8 zero power steam line break accident and a comparison to reference cycle data. The EOC zero power steam line break accident was selected since it is the most limiting zero power transient with respect to reactivity I requirements and, thus, provides the basis for verifying the Technical Specification required shutdown margin. I

! Table 5-3 shows the reactivity worths of the three CEA groups which i are allowed in the core during critical / power conditions. These I reactivity worths were calculated at full power conditions for Cycle 8 and the reference cycle. The composition of the center CEA, which is part of Bank 5, is being changed as described in Section 3.2. . I The power dependent insertion limit (PDIL) curve is the same as that of the reference cycle, j 5-1

24-57a(86H2)/cp-12 5.1.2 Power Distributions Figures 5-1 through 5-3 illustrate the all rods out (AR0) integrated radial power distributions at B0C8, M0C8 and E0C8, respectively, that are characteristic of the high burnup and of the Cycle 7 shutdown window. The high burnup end of the Cycle 7 shutdown window

tends to increase the integrated 1-pin radial power peaking. The l . integrated radial power distributions with CEA Group 5 fully inserted at beginning and and of Cycle 8 are shown in Figures 5-4 and 5-5, respectively, for the high burnup end of the - Cycle 7 i

shutdownwjndow.

The radial power distributions described in this section are calculated data without uncertainties or other allowances. However, the single rod power peaking values do include the increased peaking that is characteristic of fuel rods adjoining the water holes in the fuel assembly lattice. For both DN8 and kw/ft safety and setpoint analyses in either rodded or unrodded configurations, the power peaking values actually used are higher than those expected to occur at any time during Cycle 8. These conservative values, which are used in Section 7 of this document, establish the allowable limits for power peaking to be observed during operation.

The range of allowable axial peaking is defined by the 1.imitin Conditions for Operation (LCOsD covering Axial Shape Index (ASI)g .

Within these ASI limits, the necessary DN8R and kw/ft margins are maintained for a wide range of possible axial shapes. The maximum three-dimensional or total peaking factor anticipated in Cycle 8 during normal base load, all rods out operation at full power is 1.92, not including uncertainty allowances. l 5.1.3 Safety Related Data 5.1.3.1 Ejected CEA Data The maximum reactivity worths and planar power peaks associated with l an Ejected CEA Event are shown in Table 5-4 for Cycle 8 and the reference cycle. These values encompass the worst conditions  !

anticipated during Cycle 8 for any expected Cycle 7 termination  !

point. The values shown are the safety analysis values. '

l The data for the full power condition remain unchanged relative to the reference cycle. However, the data for the zero power condition were revised in order to perform a generic analysis. The data for both power conditions are conservative (highly so for the zero power l condition)withrespecttoactualcalculatedvalues.

5.1.3.2 Dropped CEA Data l

The Cycle 8 safety related data for this section are identical to

( the safety related data used in the reference cycle. ,

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5.2 ANALYTICAL INPUT TO IN-CORE MEASUREMENTS In-core detector measurament constants to be used in evaluating the reload cycle power distributions will be calculated by the coarse mesh code ROCS and the fine mesh code MC, as described in References 2 and 3. The use of ROCS and MC in place of PDQ, which had been

! used previously, is consistent with the change in design procedure described in Section 5.3.

5.3 NUCLEAR DESIGN METHODOLOGY Analyses have been performed with the coarse mesh code ROCS and the fine mesh code MC (Reference 3). ROCS was used in the Cycle 8 l analyses in the same manner that it was used in the reference cycle I analyses. MC replaces PDQ as the calculator of pin-by-pin data and was used in a very similar manner to the way PDQ was used in the reference cycle analyses.

5.4 UNCERTAINTIES IN MEASURED POWER DISTRIBUTIONS The power distribution measurement uncertainties to be applied to Cycle 8 are the same as those applied to the reference cycle.

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