ML19254E210
| ML19254E210 | |
| Person / Time | |
|---|---|
| Site: | Zion File:ZionSolutions icon.png |
| Issue date: | 10/22/1979 |
| From: | Peoples D COMMONWEALTH EDISON CO. |
| To: | Harold Denton Office of Nuclear Reactor Regulation |
| Shared Package | |
| ML19254E211 | List: |
| References | |
| NUDOCS 7910310322 | |
| Download: ML19254E210 (5) | |
Text
___
O One First National Plaza, Chicago, tilinois Commonwealth Edison Address Reply to: Post Office Box 767 Chicago, lihnois 60690 October 22, 1979 Dr. Harold R. Denton, Director Office of Nuclear Reactor Regulation U.S. Nuclear Regulatory Commission Washington, D.C.
20555
Subject:
Eion Station Units 1 and 2 Proposed Change to Facility Operating License Hos. DPR-39 and DPR-48 i,
NRC Docket Nos. 50-295 and 50-304
- M References (a):
" Safety Evaluation Report on g
Westinghouse Electric Company ECCS Evaluation Model for Plants Equipped with Upper Head Injection" published by U.S. Nuclear Regulatory commission in April, 1978 (b):
March 22, 1979 letter from Cerdell i,
Reed to H. R. Denton (c):
February 16, 1979 letter from A. Schwancer to Cordell Reed
Dear Dr. Denton:
(
Pursuant to 10 CFR 50.59, Commonwealth Edison Company hereby requests a change to Operating License Nos. DPR-39 and 3
. DPR-48, Appenhix A, Technical Specifications.
The purpose of this amendment is to revise the Elon Technical Specifications j
to increase the allowable LOCA peaking factor limit from the J
current value of 1.86 to a value of 2.20 based on an ECCS re-
'i analysis performed using the Westinghouse ECCS Evaluation Model approved by the NRC Staff in August 1978.
This reanalysis which is consistant with the requirements of 10 CFR 50, Appendix K, j
incorporates a drift flux calculation and related changes approved 9
by the NRC Staff in Reference (a) for use on Upper Head Injection
'i (UHI) Systems.
The proposed changes to the 51on Station Technical Specifications are enclosed in Attachment 1., which has three appendices, contains the LOCA reanalysis for tion Units 1 and 2.- Appendices A and B of Attachment 2 contain details of the
.dfift flux calculation,and related changes.
- Appendix C of Attach-sment 2 contains details of an accumulator water volume sensitivity analysis.
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The LOCA analyses of Attachment 2 were performed for i
accuaulator tank volumes from 818.65 cubic feet to 868.14 cubic feet per accus:ulator.
With this volume range, the peak clad I
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NRC Docket Nos. 30-295/304 Dr. Harold R. Denton October 22, 1979
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temperatures calculated for the limiting break (DECLG, Co== 0.6) is 2048.40F with a total core peaking factor, Fg, of 7320.
This clad temperature shows considerable excess margin to tihe 22000F limit.
Reference (b) previously. requested a revision to the LOCA peaking factor limit from the curzent value of 1.96 to a value of 1.93.
The ECCS reanalysis for'.this previous request involved two differences from the "Fo = 1.88 analysis approved by the NRC in Reference (c).
These' differences ares (1) Average fuel pellet temperature was lowered 200F based on Eion generic fuel temperature datas and (2) Average fuel pellet temperature was lowered an additional 650F to remove a 'modeling conservatism" that was previously added to the average fuel temperatures calculated by the' PAD computer code.
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The first of these two items, the sion generic fuel'
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temperature, has not been u,tilised in this new reanalysis.
The second item, deletion of the 650F *nodeling conservatism,* has been retained in this new reanalysis.
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consistent with Reference'(a), the other., specific W
differences between the reanalysis contained herein'and.the ECCS
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i "L analyses previously approved by the NRC for tion station'are (fi~
discussedindetailinAppendicesAanyBofAttachment2-and 6,
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- * :(1) The " UNI" drift hlux anosel:for both ver&ical,
n' f,- and horisontal flow which calculates the p" '
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/ ',, l-(2)! An' improved 7pses40'.'Miiscosity"' satish advolvsa:/4 44.
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n NRC Docket Nos. 60-295/305 Dr. Harold R. Denton October 22, 1979 (3) An improved pressure stability by smoothing the " equation of state" at the subcooled two-phase boundary; (4) A split downcomer model for a more realistic e
calculation of the later part of the LOCA and the distribution of injection waters (5) An improved treatment of elevation pressure changes in adjacent elements, s&ch as the downcomers,with more than one asimuthal node, in order to account for the mass redistribution resulting from fluid columns of unequal densities; (6) An additional element designated as the " break receiver" to facilitate the automatic transfer of break flow data from the SATAN coolant loop code to the containment code COCO and to permit a more exact calaulation of the break flow; and (7) The splitting of the intact loop at the pump suction node in order to properly distribute flow to the split downconer volumes (this is s
consistent with but an improvement over the UHI modeling approach to distribution of pumped flow).
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In addition, based on the Westinghouse 'Bighteen Case" analyses, a total peaking factor (Fo) of 2.13 for Sion Unit 1 Cycle 5 (expected to commence in laEe November, 1979) and 2.17
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for the current Cycle 4 of Bion Unit 2 could occur for the full range of power distributions, including load follow maneuvers, allowable under Constant Axial Offset Control (CAOC).
Therefore, NRC approval of the increase.in the FQ peaking factor limit frem 1.86 to 2.20 would eliminate the need for axial power distribution monitoring type surveillance for these and future cycles of both zion units.
In conjunction with the revised peaking factor limit modified and is included In Attachment 1.1(E) has also been of 2.20, the normalised F (E) envelope, K o
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The above considerations," proposed technical specifica-tion changes (Attachment 1), BCCS LOCA Reanalysis (Attachment ~2),
details of the driftj flum" calculation (Appendices A and B of i
. ), and detailt of the accumulator sensitivity analysis (Appendix C of Attachment'4)fbave been reviewed ~ and approved by Commonwealth Beison On-Site End Off-Site' Review with the conclus$on.
y that there are no unreviewed safety questionse.
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NRC Docket Nos. 50-295/304 Dr. Harold R. Denton October 22, 1979 tiously review and approve the license change contain The basis for this request follows.
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factor limit of 1.86, Eion Unit 2 Cycle 4 operation is prWith the curre restricted to about 96% of rated power under Constant Axial esently 9ffset Control (CAOC).
Although a Base Load mode of operation can eliminate this restriction, this type of operation significant restricts the operational flexibility of the unit.
when Zion Unit I resumes operation for Cycle 3 in late NovemberIn a 1979, the unit will be restricted to 88% of rated power und r normal operation and to less than 98% of rated power under the e
Base Load mode of operation.
of an increase in the F Therefore, an expeditious approval would eliminate these oostly power restrictions and improve thg operational flexibility of both plants.
e Pursuant to 10 CFR 170 that this proposed amendment is a, commonwealth Edison has determined cob $1ned Class III and Class I Amendment.
tance in the amount of $4 400.00As such, commonwealth Edison has encl for this proposed amendment.
Commonwealth Edison has co,ncluded that the proposed am change does not involve a significant hasards consideration since -
pndment the calculations made in support of this amendment are co with well defined and established analysis methods that have re nsistent ceived previous WRC Staff approval.
prietary to Westinghouse Electric Corporation. Ah such 4
a accompanied b information. y an affidavit signed by Westinghouse, the owner of the',
j information may be withheld from public disclosure by thThe j
and addresses with specificity the considerations listed in Para '
e Commission j
graph (b)(4) of section 2.790 of the Commission's' regulations.
Accordingly, it is respectfully requested that the -,
information which is proprietary to 16estinghouse be withh ld 'f
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$blic disclosure in accordance with 10 CFR Eection 2.7 e
rom 's Commission's regulations.
Correspondence with respect to the proprietary aspects of this application for withholding or the
.s supporting Westinghouse affidavit shoul should be addressed to R. A. Wiesemann,d reference CAW 79-28 and Legislative Affairs, Westinghouse Electric Corporation Manager, Degulatory and 355, Pittsburgh, Pennsylvania 15230.
, P. O. Box t
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NRC Docket Nos. 50-295/3C Dr. Harold R. Denton:
5-October 22, 1979 Three (3) signed o of this letter and the non riginals and thirty-seven (37) copies are provided for your use. proprietary version of Attachment 2 transmitted under separate cover. letter and the propri are being Very truly yours, D. L. Peoples Director of Nuclear Licensing WFNamaa attachments (2)
SUBSCRIBED and SWO to befo of _e M_
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Commonwealth Edison One First National Plaza, Chicago. lihnois Address Reply to: Post Office Box 767 Chicago, Illinois 60690 October 22, 1979 Dr. Harold R. Denton, Director Office of Nuclear Reactor Regulation U.S. Nuclear Regulatory Commission Washington, D.C.
20555
Subject:
Zion Station Units 1 and 2 Proposed Change to Facility Operating License Nos. DPR-39 and DPR-48 NRC Docket Nos. 50-295 and 50-304 References (a):
" Safety Evaluation Report on Westinghouse Electric Company ECCS Evaluation Model for Plants Equipped with Upper Head Injection" published by U.S. Nuclear Regulatory Commission in April, 1978 (b):
March 22, 1979 letter from Cordell Reed to H. R. Denton (c):
February 16, 1979 letter from A. Schwencer to Cordell Reed
Dear Dr. Denton:
Pursuant to 10 CFR 50.59, Commonwealth Edison Company hereby requests a change to Operating License Nos. DPR-39 and DPR-48, Appendix A, Technical Specifications.
The purpose of this amendment is to revise the Zion Technical Specifications to increase the allowable LOCA peaking factor limit from the current value of 1.86 to a value of 2.20 based on an ECCS re-analysis performed using the Westinghouse ECCS Evaluation Model approved by the NRC Staff in August 1978.
This reanalysis which is consistent with the requirements of 10 CFR 50, Appendix K, incorporates a drift flux calculation and related changes approved by the NRC Staff in Reference (a) for use on Upper Head Injection (UHI) Systems.
The proposed changes to the Zion Station Technical Specifications are enclosed in Attachment 1., which has three appendices, contains the LOCA reanalysis for Zion Units 1 and 2.
Appendices A and B of Attachment 2 contain details of the drift flux calculation and related changes.
Appendix C of Attach-ment 2 contains details of an accumulator water volume sensitivity analysis.
The LOCA analyses of Attachment 2 were performed for accumulator tank volumes from 818.65 cubic feet to 868.14 cubic feet per accumulator.
With this volume range, the peak clad g47 )Q s
n - ed.
Commonwealth Edison NRC Docket Nos. 50-295/304 2-October 22, 1979 Dr. Harold R. Denton:
temperatures calculated for the limiting break (DECLG, CD = 0.6) is 2048.40F with a total core peaking factor, FQ, of 2.20.
This 0
clad temperature shows considerable excess margin to the 2200 F limit.
Reference (b) previously requested a revision to the LOCA peaking factor limit from the current value of 1.86 to a value of 1.93.
The ECCS reanalysis for this previous request involved two differences from the "FQ = 1.86" analysis approved by the NRC in Reference (c).
These differences are:
(1) Average fuel pellet temperature was lowered 200F based on Zion generic fuel temperature data; and (2) Average fuel pellet temperature was lowered 0
an additional 65 F to remove a "modeling conservatism" that was previously added to the average fuel temperatures calculated by the PAD computer code.
The first of these two items, the Zion generic fuel temperature, has not been utilized in this new reanalysis.
The second item, deletion of the 650F "modeling conservatism," has been retained in this new reanalysis.
Consistent with Peference (a), the other specific differences between the reanalysis contained herein and the ECCS analyses previously approved by the NRC for Zion Station are discussed in detail in Appendices A and B of Attachment 2 and include the following:
(1) The "UHI" drift flux model for both vertical and horizontal flow which calculates the void fraction for flowing two-phase fluid and predicts various flow regimes as a function of the flowing void function:
(2) An improved " pseudo viscosity" which involves a better mathematical treatment, from both a physical and logical standpoint, of pressure waves passing through the system of control volumes; 1247 164
Commonwealth Edison NRC Docket Nos. 50-295/304 Dr. Harold R. Denton: October 22, 1979 (3) An improved pressure stability by smoothing the " equation of state" at the subcooled two-phase boundary; (4) A split downcomer model for a more realistic calculation of the later part of the LOCA and the distribution of injection water; (5) An improved treatment of elevation pressure changes in adjacent elements, such as the downcomers with more than one azimuthal node, in order to account for the mass redistribution resulting from fluid columns of unequal densities; (6) An additional element designated as the " break receiver" to facilitate the automatic transfer of break flow data from the SATAN coolant loop code to the containment code COCO and to permit a more exact calculation of the break flow; and (7) The splitting of the intact loop at the pump suction node in order to properly distribute flow to the split downcomer volumes (this is consistent with but an improvement over the UHI modeling approach to distribution of pumped flow).
In addition, based on the Westinghouse " Eighteen Case" analyses, a total peaking f actor (Fg) of 2.13 for Zion Unit 1 Cycle 5 (expected to commence in late November, 1979) and 2.17 for the current Cycle 4 of Zion Unit 2 could occur for the full range of power distributions, including load follow maneuvers, allowable under Constant Axial Offset Control (CAOC).
Therefore, NRC approval of the increase in the Fg peaking factor limit from 1.86 to 2.20 would eliminate the need for axial power distribution monitoring type surveillance for these and future cycles of both Zion units.
In conjunction with the revised peaking factor limit of 2.20, the normalized Fe(Z) envelope, K1(Z) has also been modified and is included In Attachment 1.
The above considerations, proposed technical specifica-tion changes (Attachment 1), ECCS LOCA Reanalysis (Attachment 2),
details of the drift flux calculation (Appendices A and B of ), and details of the accumulator sensitivity analysis (Appendix C of Attachment 2) have been reviewed and approved by Commonwealth Edison On-Site and Off-Site Review with the conclusion that there are no unreviewed safety questions.
1247 165
Commonwealth Edison NRC Docket Nos. 50-295/304 Dr. Harold R. Denton: October 22, 1979 Commonwealth Ediscn requests the NRC Staff to expedi-tiously review and approve the license change contained herein.
The basis for this request follows.
With the current Fg peaking factor limit of 1.86, Zion Unit 2 Cycle 4 operation is presently restricted to about 96% of rated power under Constant Axial Offset Control (CAOC).
Although a Base Load mode of operation can eliminate this restriction, this type of operation significantly restricts the operational flexibility of the unit.
In addition, when Zion Unit i resumes operation for-Cycle 5 in late November 1979, the unit will be restricted to 88% of rated power under normal operation and to less than 98% of rated power under the Base Load mode of operation.
Therefore, an expeditious approval of an increase in the Fg peaking factor limit to a VLlue of 2.20 would eliminate these costly power restrictions and improve the operational flexibility of both plants.
Pursuant to 10 CFR 170: Commonwealth Edison has determined that this proposed amendment is a combined Class III and Class I Amendment.
As such, Commonwealth Edison has enclosed a fee remit-tance in the amount of $4,400.00 for this proposed amendment.
Commonwealth Edison has concluded that the proposed amendment change does not involve a significant hazards consideration since the calc.:1ations made in support of this amendment are consistent with well defined and established analysis methods that have re-ceived previous NRC S taff approval. to this letter contains information pro-prietary to Westinghouse E?ectric Corporation. As such, it is accompanied by an affidavit signed by Westinghouse, the cwner of the information.
The affidavit sets forth the basis on which the information may be withheld from public disclosure by the Commission and addresses with specificity the considerations listed in Para-graph (b) (4) of Section 2.790 of the Commission's regulations.
Accordingly, it is respectfully requested that the information which is proprietary to Westinghouse be withheld from public disclosure in accordance with 10 CFR Section 2.790 of the Commission's regulations.
Correspondence with respect to the proprietary aspects of this application for withholding or the supporting Westinghouse affidavit should reference CAW 79-28 and should be addressed to R. A. Wiesemann, Manager, Regulatory and Legislative Affairs,'
~nghouse Electric Corporation, P.
O. Box 355, Pittsburgh, Penns,-ania 15230.
Please address any questions that you might have to this office.
1247 166
Commonwealth Edison NRC Docket-Nos. 50-295/304 Dr. Harold R. Denton: October 22, 1979 Three (3) signed originals and thirty-seven (37) copies of this letter and the non-proprietary version of Attachment 2 are provided for your use.
In additiona, six (6) copies of this letter and the proprietary version of Attachment 2 are being transmitted under separate cover.
Very truly yours, q.
i D.
L. Peoples Director of Nuclear Licensing WFN:mae attachments (2)
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