ML19345F217
| ML19345F217 | |
| Person / Time | |
|---|---|
| Site: | Trojan File:Portland General Electric icon.png |
| Issue date: | 02/05/1981 |
| From: | PORTLAND GENERAL ELECTRIC CO. |
| To: | |
| Shared Package | |
| ML19345F216 | List: |
| References | |
| TAC-43444, NUDOCS 8102100498 | |
| Download: ML19345F217 (10) | |
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LCA 70 Page 1 of 3 LICENSE CHANGE APPLICATION 70 Add the following to the end of Paragraph 2.C.(ll) of the Trojan Facility Operating License:
Fuel Assemblies
'The requirements of Technical Specification 5.3.1 that each fuel assembly contain 264 fuel rods are further waived ia that two fuel assemblies in the core will each contain three stainless steel rods in place of three fuel rods. This waiver is limited to two fuel cycles subsequent to the third fuel cycle, but not necessarily the two fuel cycles immediately following the third fuel cycle."
REASON FOR CHANGE Amendment No. 45 to Facility Operating License NPF-1 for the Trojan Nuclear Plant aAlowed the use of two modified fuel assemblies during the third fuel cycle. A change to the Facility Operating License is necessary to allow for the continued use of these fuel assembliec during subsequent fuel cycles and to allow the assemblies to be relocated within the core in accordance with core management consideratiore.
SAFETY / ENVIRONMENTAL EVALUATION 1.
Summary of Change n
Two fuel assemblies were modified for Cycle 3 operation as a result of the baffle jet problem described in Lic' 4see Event Report (LER) 80-06.
Three fuel rods in each of twc assaaies were replaced with solid stainless steel rods of -
_.ch and diameter as the fuel rods.
The madifi mo.Aes were located on the outside of the Cycle 3
- core,
-os. cat o the baffle corners where jet impingement-induced fuel l
damage had occurred.
Technical Specification 5.3.1 requires that the core contain 193 fuel assemblies with each fuel assembly containing 264 fuel rods clad with Zircaloy-4. In Amendment 45 to Facility Operating License NPF-1, the NRC granted a waiver from Technical Specification 5.3.1 which allowed the location of the two modified fuel assemblies in core locations B-12 and M-2 for Cycle 3 operation.
The baffle gaps will be closed during the refueling outage at the end of Cycle 3.
An extension of this waiver is needed to allow for use of the two modified fuel assemblies for two cycles beyond Cycle 3 and for their relocation within the core.
2.
Discussion The Safety / Environmental Evaluation submitted under License Change l
Application 61 (LCR TNP-80-06) for the waiver of Technical Specifica-tion 5.3.1 for the Cycle 3 core is applicable here, supplemented with a discussion of the effects of relocation of the two assemblies withiu l
the core.
1 8102100 ] [
I4A 70 Og e 2 of 3 Core 1c: Jing patterns will be developed to provide the required cycle i
onergy output consistent with the presence of the two modified assemblies.
The stainless steel rodded assemblies will be located such that they will not be the predicted peak power assemblies at the beginning of the cycle when the hot channel factors are closest to their limita. Attached is the Westinghouse evaluation for the use of the two modified assemblies in the Cycle 4 core. A similar evaluation will be performed for any i
other fuel cycles that might include the stainless-steel-rodded assemblies.
Since the effects due to substitution of the stainless steel rods are i
small, the conclasion that the use of stainless steel rod-bearing assemblies can be accommodated in normal fuel management schemes is ll valid for two additional fuel cycles beyond the third cycle.
l 3.
Effect on Technical Specifications Including Design Basis I
A waiver of Technical Specification 5.3.1 is necessary to allow continued usage of the stainless-steel-rodded assemblies since they contain less than 264 fuel rods. Being descriptive in nature, the Design Feature l
Specifications have no specific bases and thus the Bases for Technical Specifications are unaffected. Since the effects of the stainless steel rods are small, no change to the existing power distribution limit Technical Specifications is necessary.
4.
Effect on FSAR I
Mechanical design of the fuel is described in FSAR Section 4.2.1, nuclear design in Section 4.3, and thermal-hydraulic design in Section 4.4 The l
effects of the stainless steel dummy rods are expected to be minimal an1 I
within the tolerances and allowances accounted for in the Safety Analysis f
Re po rt.
The mechanical design is essentially identical and the effects I
on nuclear and thermal-hydraulic design will be accountad for in the fuel management program and reload safety analyses; no changes are required to the FSAR. The modified assemblies will be inspected for damage at the end of the third fuel cycle. As a result of the negligible effects of j
this LCR on mechanical design, nuclear design, and thermal-hydraulic design, this change is not cocaidered to involve an unreviewed safety 4
question and will not increase the probability or consequence of accidents previously considered, nor will it create any new accidents.
5.
Environmental Effects The proposed change will not change effluent types or increase amounts.
No unreviewed environmental matter exists and there will be no significant impact on the environment from this change.
SCHEDULE CONSIDERATIONS Prompt review and approval of this LCA is requested in order to finalize the Cycle 4 core loading pattern and the corresponding reload safety analyses without impacting the refueling outage scheduled for this Spring.. Approval of this LCA is requested no later than April 1, 1981.
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LCA 70 Page 3 of 3 i
i BASIS FOR DETERMINATION OF AMENDMENT CLASS 4
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This LCA has has been determined to result in a Class III amendment in accordance with the criteria of 10 CFR 170.22. This LCA involves a single issue and does not involve a significant hazard consideration.
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WESTINGHOUSE PRCPRIETARY CLA03 3 LCA 70 Attachmene A Page 1 of 7 Evaluation for the Use of Fuel Assemblies Containing Stainless Steel Fuel Red
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Replacements I.
Introduction A preliminary evaluation of the Trojan Cycle 4 design has been completed to support efforts to license the use of the two stainless steel (SSJ red bearing Region 5 assemblies in Cycle 4 and subsequent cycles. The design bases for Cycle 4 are sumarized in Table 1.
Discussed in this report is the preliminary Cycle 4 loading pattern, the effect of moving the SS rod bearing assemblies inboard,' and preifminary evaluation of safety related parameters such as F versus power, Fxy(z),andshutdownmargin.
g II.
Preliminary leading Pattern A preliminary loading pattern for Cycle.4 which satisfies the design bases in Table 1 is presented in Figure 1.
Core narameters such as critical boron concentrations and peaking factors are sumarized in Table 2 for the nominal Cycle 3 burnup. The tentative locations of the two SS rod bearing assemblies are in positions H-04 and H-12 which are midway between the periphery and the core center. These two assemblies differ from their symetric counterparts in two ways:
- 1) the replacement of 3 fuel rods with 3 55 rods in each, and 2) the SS rod bearing assemblies have slightly lower burnup, reflecting the fact that assembly powers were slightly less in these assemblies during Cycle 3 due to the SS rods.
Another consideration in the detennination of the Cycle 4 preliminary leading pattern is the mixing of assemblies from the different quadrants in Cycle 3.
i Quadrant mixing is done te satisfy two purposes: 1) to minimize the ARO, HFP peaking factor, and 2) to shuffle fuel in a manner that will minimize quadrant power asymetry in Cycle 4.
Since measured assembly burnup data is not available for end-of-cycle 3 at the time that the initial loading pattern was established.
the pattern was first established using design burnups, and the initial cross quadrant shuffles for tilt minimization are done on a random mixing basis.
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ya WEsTINcHOUsE PROPRIETARY class 3 nent A Pne 2 of 7 f
Later, as measured burnup data beccmes more available, the end-of-cycle measured burnups can be extrapolated, and these burnups will be used in Cycle 4 to determine the optimum cross quadre t shuffling.
Effects of Stainless Steel Rods III.
As noted in the previous section, the stainless steel rod bearing assemblies have been shuffled to locations H-04 and H-12 in Cycle 4 from locations M-02 and B-12, respectively, in Cycle 3.
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Power peaking in these assemblies is affected by both the presence of the j
stainless steel rods and by the slightly reduced burnup (s 50 MWD /MTU) in j
these assemblies as compared to their symetric counterparts. The impact l
, of these differences on power peaking have been evaluated by comparing the f
ratio of peak rod power to assembly average power in assembl_fes with SS rods
[
with the peak to average ratio in symetric locations. This comparison is shown in Table 3.
The four assemblies included in Table 3 are in symetric axis locations.
It can be seen that the peak to average ratio for assembly i
H-12 (with SS rods) is greater by %.02 while in assembly H-04 (with SS) no f
significant increase is noted. This. appears to be related to the position of the peak red relative to the location of the SS rods within the assembly.
In H-12 the peak rod occurs next to a guide tube near the SS rods, while in H-04 the peak rod occurs in the assembly quadrant opposite from the'SS rods.
f A similar evaluation of power peaking in assemblies with faces adjacent to j
the SS rods indicates only a small increase in the peak to average ratio.
It
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should be noted that the increased peaking due to the SS rods is accounted for i
in the design by the use of a full core modified discrete model.
f l
In addition to the effects of SS rod bearing assemblies on power peaking, an f
analysis was done to detennine the sensitivity of the loading pattern to the l
location of the SS rod bearing assembites.
Based on a full core 2-0 nodal
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medel it was concluded that at BOL, HFP, ARO conditions, the movement of the l
SS red bearing assemblies from the vertical axis position to either main diagonal 4
increases the peak F very slightly (i.e., less than 0.4t). This is attributable g
to a ccmhination of the effects of SS rods and the reduced assembly burnups in l
the SS rod bearing assemblies.
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WESTINGHOUSE PROPRIETARY class 3 A a
.ent A Page 3 of 7 IV.
preifminary Evaluatien of Safety Related Parameters Certain key safety related parameters including peak Fg versus pcwer, F,y(:),
moderator temperature coefficients and shutdown margin were evaluated for this preliminary loading pattern for Cycle 4.
-A.
Initial calculations indicate that all F limits should be met and that g
the peak F occurs near a Cycle 4 burnup of 150 MWD /MTU. Table 2 sum.arizes g
these rodded and unrodded peak F calculations for the Cycle 4 model based g
l on Cycle 3 burnup of 9600 MWD /MTU. Note that in Table 2 that the HFr ARO and D in peak Fg's along with the HZP D in and 0+C in peak Fg's are sufficiently 7ow enough that F versus power restraints should be met.
g Last, preliminary 3-D checks of F (z)indicatethatcurrentlimitsare l
not violated.
B.
Initial moderator temperature coefficient (MTC) calculations indicate that the MTC is slightly positive.
Hcwever, administrative limits en 0 bank withdrawal at low power levels would insure a non-positive MTC.
C.
Preliminary calculations for N-1 centrol rod worth show that while the worst stuck red is of greater worth in Cycle 4 than in Cycle 3, the N rod worth is also greater in Cycle 4.
Therefore, the available N-1 worth is sufficient.
V.
Conclusions On the basis of this evaluation it ts concluded that the use of the stainless steel red bearing assemblies can be accomodated in nomal fuel management schemes. As was expected, slight increases in power peaking were observed in assemblies with stainless steel rods. However, these effects are accounted for in the design models and pose no significant difficulties.
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LCA 70 WESTINGHOUSE PRCPRIETARY CLAes 3 Attach:nent A Pace /* of 7 TABLE 1 Su:r.ary of Cycle 4 Cesign Bases
. A.
Two Regien 5 fuel assemblies with 3 stainless steel rods in each will be used.
B.
Core loading in Cycle 4:
Feed 56 Region 6 FA's fresh 3.2 w/o U-235 Use 64* Region 5 FA's once burned 3.1 w/o U-235 Use 62 Region 4 FA's twice burned 3.1 w/o U-235 Use 1 Region 3 FA twice burned 3.1 w/o U-235 Use O Region 2 FA's twice burned 2.6 w/o U-235 Use 10 Region 1 FA's once burned 2.1 w/o U-235
- Includes two FA's with 3 stainless steel rods each C.
Cycle 4 burnup is 9950 Mht/MTU D.
Based on:
Cycle 3 Burnup = 9600 + 500 MWD /MTU Cycle 2 Burnup = 11180 MWD /MTU Cycle 1 Burnup = 16000 Mht/MTU G
WESTINGHOUSE PRCPRIETARY CLASS 3 A achm.ent A Page 5 of 7 TABLE 2 Trojan Cycle 4 Su. mary Preliminary Leading Pattern
- 150 MWD /MTU Burnup Cycle 4 Nominal Cy:le 3 Burnup Core Condition E0C3=9600 MWD /MTU HFP CB= 027 ppm F
9 Location **
y ARO 1.354 (3,1)
D In 1.399 (2,7)
D+C In 1.633 (4,7)
NZP Cg = 1164 ppm
.$.9 Location F
ARO 1.395 (4,2)
D In 1.441 (2,7)
D+C In 1.814 (4,7) l l
- B'OL ARO HFP: Cg = 1321 ppm & Fg = 1.350 9 (4,5)
- Locations are designated in quartercore notation
i WESTINGHOUSE PROPRIETARY CLASS 3 LCA 70 Attachment A Page 6 of 7 TABLE 3 Ratics of Peak Red Power to Assembly Average Power Assembly Peak / Average location Pcwer Ratio H-12*
1.094 '
H-04*
1.073 M-08 1.073 0-08 1.077
- 55 rod bearing assembly 1
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LCA 70 i -
WESTINGHOUSE PRCPRIETARY CLAS3 3 Attachment A Page 7 of 7 i
FIGURE 1 Trojan Cycle 4 Preliminary Leading Pattern A
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