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| issue date = 02/02/1993
| issue date = 02/02/1993
| title = Suppls Listed Responses to NRC Bulletin 90-002, Loss of Thermal Margin Caused by Channel Box Bow, Effect on Cycle 9 Operation.Requests NRC Approval for Plan to Reuse Channel Boxes During Cycle 9
| title = Suppls Listed Responses to NRC Bulletin 90-002, Loss of Thermal Margin Caused by Channel Box Bow, Effect on Cycle 9 Operation.Requests NRC Approval for Plan to Reuse Channel Boxes During Cycle 9
| author name = SORENSEN G C
| author name = Sorensen G
| author affiliation = WASHINGTON PUBLIC POWER SUPPLY SYSTEM
| author affiliation = WASHINGTON PUBLIC POWER SUPPLY SYSTEM
| addressee name =  
| addressee name =  
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=Text=
=Text=
{{#Wiki_filter:ACCELERATE'D DOCUMENT DIS'103BUTION SYSTEM REGULATORY INFORMATION DISTRIBUTION SYSTEM (RIDS)ACCESSION NBR:9302120132 DOC.DATE: 93/02/02 NOTARIZED:
{{#Wiki_filter:ACCELERATE'D DOCUMENT                             DIS'103BUTION SYSTEM REGULATORY INFORMATION           DISTRIBUTION SYSTEM     (RIDS)
YES FACIL:50-397 WPPSS Nuclear Project, Unit 2, Washington Public Powe AUTH.NAME AUTHOR AFFILIATION
ACCESSION NBR:9302120132             DOC.DATE: 93/02/02         NOTARIZED: YES         DOCKET  N FACIL:50-397   WPPSS   Nuclear Project, Unit 2, Washington Public             Powe 05000397 AUTH. NAME           AUTHOR AFFILIATION
, SORENSEN,G.C.
, SORENSEN,G.C.         Washington Public Power Supply System RECIP.NAME           RECIPIENT AFFILIATION Document Contxol Branch (Document Control Desk)
Washington Public Power Supply System RECIP.NAME RECIPIENT AFFILIATION Document Contxol Branch (Document Control Desk)DOCKET N 05000397


==SUBJECT:==
==SUBJECT:==
Suppls listed responses to NRC Bulletin 90-002,"Loss of Thermal Margin Caused by Channel Box Bow," effect on Cycle 9 operation.
Suppls     listed   responses       to NRC Bulletin 90-002, "Loss of Thermal Margin Caused           by Channel Box Bow,"     effect on Cycle 9 operation. Requests NRC           approval   for plan to reuse channel boxes during Cycle 9.
Requests NRC approval for plan to reuse channel boxes during Cycle 9.DISTRIBUTION CODE: IE38D COPIES RECEIVED:LTR ENCL SIZE: TITLE: NRC Bulletin 90-002, Loss of Thermal Margin Caused by Channel Box Bow NOTES: RECIPIENT ID CODE/NAME.PD5 LA CLIFFORDF J INTERNAL: AEOD/DOA NRR FIENO,D NRR/DET/EMEB 7E NRR/DOEA/OGCBll NRR/Dggf 8E2 GREG FILED 02 RGN5 FILE 01 EXTERNAL: NRC PDR COPIES LTTR ENCL 1 0 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 RECIPIENT ID CODE/NAME PD5 PD AEOD/DSP/TPAB NRR LONGFW PD31 NRR/DOEA/OEAB11 NRR/DREP/PEPB9D NRR/PMAS/ILRB12 RES/DSIR/EIB NSIC COPIES LTTR ENCL 1 1 1-1 1 1 1 1 1 1 1 1 1 1 1 1 NOTE TO ALL"RIDS" RECIPIENTS PLEASE HELP US TO REDUCE WASTE!CONTACT THE DOCUMENT CONTROL DESK, ROOM Pl-37 (EXT.504-2065)TO ELIMINATE YOUR NAME FROM DISTRIBUTION LISTS FOR DOCUMENTS YOU DON'T NEED!TOTAL NUMBER OF COPIES REQUIRED: LTTR 18 ENCL 17 A WASHINGTON PUBLIC POWER SUPPLY SYSTEM P.O.Bax 968~3000 George Wasbtngton Way~Rtcbland, Wasbtngton 99352496'8
DISTRIBUTION CODE: IE38D           COPIES RECEIVED:LTR           ENCL       SIZE:
~(509)372-5000 February 2, 1993 G02-93-024 Docket No.50-397 U.S.Nuclear Regulatory Commission Attn: Document Control Desk Washington, D.C.20555  
TITLE: NRC   Bulletin   90-002, Loss of Thermal Margin Caused by Channel Box             Bow NOTES:
RECIPIENT             COPIES              RECIPIENT          COPIES ID CODE/NAME            LTTR ENCL          ID CODE/NAME       LTTR ENCL
            . PD5 LA                     1      0      PD5 PD                1      1 CLIFFORDF J                 1      1 INTERNAL: AEOD/DOA                       1      1      AEOD/DSP/TPAB          1    -1 NRR FIENO,D                 1      1      NRR LONGFW PD31        1      1 NRR/DET/EMEB 7E             1      1      NRR/DOEA/OEAB11        1     1 NRR/DOEA/OGCBll            1      1      NRR/DREP/PEPB9D       1      1 NRR/Dggf 8E2                1      1      NRR/PMAS/ILRB12       1      1 GREG FILED          02        1      1      RES/DSIR/EIB           1     1 RGN5    FILE 01            1       1 EXTERNAL: NRC PDR                        1       1       NSIC                  1     1 NOTE TO ALL"RIDS" RECIPIENTS PLEASE HELP US TO REDUCE WASTE! CONTACT THE DOCUMENT CONTROL DESK, ROOM Pl-37 (EXT. 504-2065) TO ELIMINATEYOUR NAME FROM DISTRIBUTION LISTS FOR DOCUMENTS YOU DON'T NEED!
TOTAL NUMBER OF COPIES REQUIRED: LTTR                 18   ENCL   17
 
A WASHINGTON PUBLIC POWER SUPPLY SYSTEM P.O. Bax 968 ~ 3000 George Wasbtngton Way ~ Rtcbland, Wasbtngton 99352496'8 ~ (509) 372-5000 February 2, 1993 G02-93-024 Docket No. 50-397 U.S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, D.C. 20555


==Subject:==
==Subject:==
%NP-2, OPERATING LICENSE NPF-21 RESPONSE TO NRC BULLETIN NO.90-02: "LOSS OF THERMAL MARGIN.CAUSED BY CHANNEL BOX BOW", EFFECT ON CYCLE 9 OPERATION (TAC No.M82920)
        %NP-2, OPERATING LICENSE NPF-21 RESPONSE TO NRC BULLETINNO. 90-02: "LOSS OF THERMAL MARGIN.CAUSED BY CHANNEL BOX BOW", EFFECT ON CYCLE 9 OPERATION (TAC No. M82920)


==References:==
==References:==
: 1.      NRC Bulletin No. 90-02, March 20, 1990, "Loss of Thermal Margin Caused by Channel Box Bow"
: 2.        Letter, G02-90-075, April 13, 1990, GC Sorensen (SS) to of WNP-2 Cycle 6 Reload Submittal and Response to NRC  USNRC,'Modification Bulletin No. 90-02: Loss of Thermal margin Caused by Channel Box Bow"
: 3.      ANF-524(P)(A), Rev. 2, Supplements 1 and 2, November 1990, "Advanced Nuclear Fuels Corporation Critical Power Methodology for Boiling Water Reactors"
: 4.      Letter, G02-90-162, September 28; 1990, GC Sorensen (SS) to USNRC, "Final Response to NRC Bulletin No. 90-02: Loss of Thermal Margin
                          . Caused by Channel Box Bow"
: 5.      Letter, G02-91-037, February 25, 1991, GC Sorensen (SS) to USNRC, "Request for Additional Information Regarding NRC Bulletin 90-02, Loss of Thermal Margin Caused by Channel Box Bow"
: 6.      Letter, April 22, 1991, PL Eng (NRC) to GC Sorensen (SS), "Evaluation of Response to NRC Bulletin No. 90-02: Loss of Thermal Margin Caused by Channel Box Bow (TAC No."'76354)"
: 7.      Letter, G02-92-048, February 25, 1992, GC Sorensen to USNRC, "Response to NRC Bulletin No. 90-02: Loss of Thermal Margin Caused by Channel Box Bow, Effect on Cycle 8 Operation"
: 8.      Letter, June 15, 1992, WM Dean (NRC) to GC Sorensen, "Evaluation of Response to NRC Bulletin No. 90-02: Loss of Thermal Margin Caused by Channel Box Bow (TAC No. M82920)"
g)Oc;t        h 9302i20l32 9302020500039'7 PDR    ADOCK PDR


1.NRC Bulletin No.90-02, March 20, 1990,"Loss of Thermal Margin Caused by Channel Box Bow" 2.Letter, G02-90-075, April 13, 1990, GC Sorensen (SS)to USNRC,'Modification of WNP-2 Cycle 6 Reload Submittal and Response to NRC Bulletin No.90-02: Loss of Thermal margin Caused by Channel Box Bow" 3.ANF-524(P)(A), Rev.2, Supplements 1 and 2, November 1990,"Advanced Nuclear Fuels Corporation Critical Power Methodology for Boiling Water Reactors" 4.Letter, G02-90-162, September 28;1990, GC Sorensen (SS)to USNRC,"Final Response to NRC Bulletin No.90-02: Loss of Thermal Margin.Caused by Channel Box Bow" 5.Letter, G02-91-037, February 25, 1991, GC Sorensen (SS)to USNRC,"Request for Additional Information Regarding NRC Bulletin 90-02, Loss of Thermal Margin Caused by Channel Box Bow" 6.Letter, April 22, 1991, PL Eng (NRC)to GC Sorensen (SS),"Evaluation of Response to NRC Bulletin No.90-02: Loss of Thermal Margin Caused by Channel Box Bow (TAC No."'76354)" 7.Letter, G02-92-048, February 25, 1992, GC Sorensen to USNRC,"Response to NRC Bulletin No.90-02: Loss of Thermal Margin Caused by Channel Box Bow, Effect on Cycle 8 Operation" 8.Letter, June 15, 1992, WM Dean (NRC)to GC Sorensen,"Evaluation of Response to NRC Bulletin No.90-02: Loss of Thermal Margin Caused by Channel Box Bow (TAC No.M82920)" g)Oc;t h 9302i20l32 930202 PDR ADOCK 0500039'7 PDR Page Two RESPONSE TO NRC BULLETIN NO.90-02: "LOSS, OF THERMAL MARGIN CAUSED BY CHANNEL BOX BOW", EFFECT ON CYCLE 9 OPERATION (TAC No.M82920)Reference,1 requested that licensees reusing channel boxes verify that current Minimum Critical Power Ratio (MCPR)Technical Specification operating and safety limits are met.All affected licensees were requested to advise the NRC of the number and location of such channel boxes and to describe the methods and associated data base used to account for the effects of channel box bow during reuse of channel boxes to ensure conformance with the CPR limits.The Supply System responded to this bulletin in References 2, 4, 5 and 7.Reference 6 provided WNP-2 the NRC evaluation of the issues for Cycle 7, and Reference 8 for Cycle 8.Reference 6'required that the reuse of channel boxes in future cycles be evaluated on a cycle specific basis.This letter responds to those requirements for WNP-2 Cycle 9.The effect of potential channel box bow on CPR limits was evaluated in the Cycle 9 design.WNP-2, a C-lattice BWR, is less susceptible than a D-lattice BWR to the phenomena of and effects from channel box bow.The Supply System, aware of the potential problems associated with channel box bow, has had a channel management program in place since initial operation of WNP-2.The WNP-2.channel management program consists of data collection on channel operating history and actual measurement of channel distortion as a function of channel.operation.
Page Two RESPONSE TO NRC BULLETINNO. 90-02: "LOSS, OF THERMAL MARGIN CAUSED BY CHANNEL BOX BOW", EFFECT ON CYCLE 9 OPERATION (TAC No. M82920)
The current goal of the channel management program is to use a channel box for a single assembly lifetime.To achieve this goal, the Supply System is currently putting new channels on new fuel.During the transition the Supply System will discharge channels predicted , to achieve a target burnup of approximately 50 GWd/MTU in a cycle or perform an analysis to justify continued use.Reference 4 discusses the basis for the selection of the exposure target and analytical methodology.
Reference,1 requested that licensees reusing channel boxes verify that current Minimum Critical Power Ratio (MCPR) Technical Specification operating and safety limits are met. All affected licensees were requested to advise the NRC of the number and location of such channel boxes and to describe the methods and associated data base used to account for the effects of channel box bow during reuse of channel boxes to ensure conformance with the CPR limits.
In Cycle 8, 291 of the 764 channels in the WNP-2 core were reused channels.In Cycle 9 there will be 232 reused channels.Twenty-four (24)channels will be replaced at the end of Cycle 8 because their exposures at the end of Cycle 9 are expected to exceed 50 GWd/MTU.These channels will be replaced with less exposed channels from the spent fuel pool.Each of the 24 replacement channels has been measured for channel box bow and bulge and meets the pre-determined acceptance criteria of Reference 4.At the end of Cycle 9, the peak reused channel exposure is predicted to be less than 49 GWd/MTU.EXPOSURE RANGE~d/UANTITY 27-34 34-41 41-48 42-42 148  
The Supply System responded to this bulletin in References 2, 4, 5 and 7. Reference 6 provided WNP-2 the NRC evaluation of the issues for Cycle 7, and Reference 8 for Cycle 8. Reference 6
~~Page Three RESPONSE TO NRC BULLETIN NO.90-02: "LOSS OF THERMAL MARGIN CAUSED BY CHANNEL BOX BOW", EFFECT ON CYCLE 9 OPERATION (TAC No.M82920).Beginning with Cycle 7, the effects of channel box bow were addressed in WNP-2 reload design using the approved Siemens Power Corporation (SPC)methodology for determining the Safety Limit Minimum Critical Power Ratio (SLMCPR)(Reference 3).The SPC data incorporated in the SPC methodology has been reviewed previously by the NRC (including WNP-2 measured data)and along with the methodology has been approved by the NRC (Reference 3).The SLMCPR established for Cycle 9 operation of WNP-2 will include the effects of channel box bow as analyzed by this methodology.
'required that the reuse of channel boxes in future cycles be evaluated on a cycle specific basis.
During Cycle 9, 232 reused channels will be in the WNP-2 core, The planned location coordinates for each reused channel for Cycle 9 are given in Table 1.The location of each reused channel is also indicated on the attached Figure 1 (core map)by assembly number.The appropriate channel number for each assembly number can be determined from Table 1.A total of 76 of the reused channels will be located face adjacent to new fuel assemblies.
This letter responds to those requirements for WNP-2 Cycle 9. The effect of potential channel box bow on CPR limits was evaluated in the Cycle 9 design.
Experience has'shown that limiting assemblies are almost always once burned assemblies and, potentially at the end of a long cycle, fresh assemblies can be limiting.However, the precise location of limiting assemblies during Cycle 9 will be dependent upon the actual operating experience.
WNP-2, a C-lattice BWR, is less susceptible than a D-lattice BWR to the phenomena of and effects from channel box bow. The Supply System, aware of the potential problems associated with channel box bow, has had a channel management program in place since initial operation of WNP-2. The WNP-2.channel management program consists of data collection on channel operating history and actual measurement of channel distortion as a function of channel.
A reused channel could, therefore, be adjacent to a limiting assembly at some ti'me during Cycle.9 operation.
operation. The current goal of the channel management program is to use a channel box for a single assembly lifetime. To achieve this goal, the Supply System is currently putting new channels on new fuel. During the transition the Supply System will discharge channels predicted
The probability of this occuring is recognized and taken'into account in calculation of the SLMCPR using the SPC methodology.
, to achieve a target burnup of approximately 50 GWd/MTU in a cycle or perform an analysis to justify continued use. Reference 4 discusses the basis for the selection of the exposure target and analytical methodology.
Channel distortion (bow+bulge), magnitude and direction, is directly dependent upon the location history of the channels.The channels that will have the largest estimated exposure at end of cycle are channels 60890 and 73399.The channels will reside in core location 23,2 and 23,29 respectively (row and column coordinates from the upper left corner as shown in Figure 1).The Supply System analytical model predicts a maximum calculated total distortion for these channels to be less than 105 mils.Total distortions for the other reused channels in WNP-2 shown in Table 1 are predicted to be less than this value.The anticipated effect of maximum channel bow is accounted for in the MCPR operating limit by modification of the SLMCPR, which is a part of the MCPR operating limit.The WNP-2 SLMCPR is established through statistical consideration of measurement and calculational uncertainties associated with the thermal hydraulic state of the reactor using design basis radial, axial and local power distributions and considering fuel channel bow.Reference 3 discusses vendor MCPR safety limit methodology and describes in detail how channel bow effects are incorporated irito, the MCPR safety limit.The effects of channel bow increase the WNP-2 Cycle 9 MCPR safety limit by about 0.02, P Page Fqur RESPONSE TO NRC BULLETIN NO.90-02: "LOSS OF THERMAL MARGIN CAUSED BY CHANNEL BOX BOW", EFFECT ON CYCLE 9 OPERATION (TAC No.M82920)In accordance with the requirements of IEB 90-02 and Reference 6, the Supply System is requesting NRC approval for this plan for the reuse of channel boxes during Cycle 9.The channels are to be loaded into the core during the spring 1993 refueling outage, scheduled for 45 days beginning in April.Therefore, prompt NRC approval of this submittal would be appreciated.
In Cycle 8, 291 of the 764 channels in the WNP-2 core were reused channels. In Cycle 9 there will be 232 reused channels. Twenty-four (24) channels will be replaced at the end of Cycle 8 because their exposures at the end of Cycle 9 are expected to exceed 50 GWd/MTU. These channels will be replaced with less exposed channels from the spent fuel pool. Each of the 24 replacement channels has been measured for channel box bow and bulge and meets the pre-determined acceptance criteria of Reference 4. At the end of Cycle 9, the peak reused channel exposure is predicted to be less than 49 GWd/MTU.
Sincerely, G.C.Sorensen, Manager Regulatory Programs (Mail Drop PE20)JDF:bw Attachments:
                        ~d/
1;2.Table 1;Reused Channels, Assemblies And Projected Exposure Figure 1;Cycle 9 Load Pattern Showing Assemblies with Reused, Channels CC: JB Martin-NRC RV NS Reynolds-Winston&Strawn JD Clifford-NRC DL Williams-BPA/399 NRC Site Inspector-901A STATE OF WASHINGTON
EXPOSURE RANGE UANTITY 27 - 34                               42-34 - 41                               42 41-48                                 148
))COUNTY OF BENTON)
 
Page Three
                          ~                                       ~
RESPONSE TO NRC BULLETINNO. 90-02: "LOSS OF THERMAL MARGIN CAUSED BY CHANNEL BOX BOW", EFFECT ON CYCLE 9 OPERATION (TAC No. M82920)
. Beginning with Cycle 7, the effects of channel box bow were addressed in WNP-2 reload design using the approved Siemens Power Corporation (SPC) methodology for determining the Safety Limit Minimum Critical Power Ratio (SLMCPR) (Reference 3). The SPC data incorporated in the SPC methodology has been reviewed previously by the NRC (including WNP-2 measured data) and along with the methodology has been approved by the NRC (Reference 3). The SLMCPR established for Cycle 9 operation of WNP-2 will include the effects of channel box bow as analyzed by this methodology.
During Cycle 9, 232 reused channels will be in the WNP-2 core, The planned location coordinates for each reused channel for Cycle 9 are given in Table 1. The location of each reused channel is also indicated on the attached Figure 1 (core map) by assembly number. The appropriate channel number for each assembly number can be determined from Table 1. A total of 76 of the reused channels will be located face adjacent to new fuel assemblies. Experience has 'shown that limiting assemblies are almost always once burned assemblies and, potentially at the end of a long cycle, fresh assemblies can be limiting. However, the precise location of limiting assemblies during Cycle 9 will be dependent upon the actual operating experience. A reused channel could, therefore, be adjacent to a limiting assembly at some ti'me during Cycle.
9 operation. The probability of this occuring is recognized and taken'into account in calculation of the SLMCPR using the SPC methodology.
Channel distortion (bow + bulge), magnitude and direction, is directly dependent upon the location history of the channels. The channels that will have the largest estimated exposure at end of cycle are channels 60890 and 73399. The channels will reside in core location 23,2 and 23,29 respectively (row and column coordinates from the upper left corner as shown in Figure 1). The Supply System analytical model predicts a maximum calculated total distortion for these channels to be less than 105 mils. Total distortions for the other reused channels in WNP-2 shown in Table 1 are predicted to be less than this value.
The anticipated effect of maximum channel bow is accounted for in the MCPR operating limit by modification of the SLMCPR, which is a part of the MCPR operating limit. The WNP-2 SLMCPR is established through statistical consideration of measurement and calculational uncertainties associated with the thermal hydraulic state of the reactor using design basis radial, axial and local power distributions and considering fuel channel bow. Reference 3 discusses vendor MCPR safety limit methodology and describes in detail how channel bow effects are incorporated irito, the MCPR safety limit. The effects of channel bow increase the WNP-2 Cycle 9 MCPR safety limit by about 0.02, P
 
Page Fqur RESPONSE TO NRC BULLETINNO. 90-02: "LOSS OF THERMAL MARGIN CAUSED BY CHANNEL BOX BOW", EFFECT ON CYCLE 9 OPERATION (TAC No. M82920)
In accordance with the requirements of IEB 90-02 and Reference 6, the Supply System is requesting NRC approval for this plan for the reuse of channel boxes during Cycle 9. The channels are to be loaded into the core during the spring 1993 refueling outage, scheduled for 45 days beginning in April. Therefore, prompt NRC approval of this submittal would be appreciated.
Sincerely, G. C. Sorensen, Manager Regulatory Programs (Mail Drop PE20)
JDF:bw Attachments:   1;     Table 1; Reused Channels, Assemblies And Projected Exposure
: 2. Figure 1; Cycle 9 Load Pattern Showing Assemblies with Reused, Channels CC:     JB Martin - NRC RV NS Reynolds - Winston   & Strawn JD Clifford - NRC DL Williams - BPA/399 NRC Site Inspector - 901A
 
STATE OF WASHINGTON )                                          


==Subject:==
==Subject:==
Res onse to IEB 90-02 I.G.C.SORENSEN, being duly sworn, subscribe to and say that I am the Manager, Regulatory Programs for the WASHINGTON PUBLIC POWER SUPPLY SYSTEM, the applicant herein;that I have the full authority to execute this oath;that I have reviewed the foregoing; and that to'he best of my knowledge, information, and belief the statements made in it are true.DATE Z HWMdyd'C/Ayy&
Res onse to IEB 90-02
, 1993 G.C.Sor nsen, Manager Regulatory Programs On this date personally appeared before me G.C, SORENSEN, to me known to be the individual who executed the foregoing instrument, and acknowledged that he signed the same as his free act and deed for the uses and purposes herein mentioned.
                              )
GIVEN under my hand and seal this~tday of 1993~M(otary Public in and for the STATE OF WASHINGTON Residing at Kennewick Washin ton My 2 y y 2*Ay~A'I 2 I Reused Table 1 Channels, Assemblies', and Projected EOC 9 Exposures Row Column Current Assembly Channel ID Proj.EOC 9 Exposure 1 1 1 1 1 1 1 1 1 1 1 1 1 1 2 2 3 3.3 3 3 3 4 4 4 4 4 4 5 5 5 5 5 6 6 6 6 6 6 6 6 6 6 6 9 10 11 12 13 14 15 16,, 17 18 19 20 21 22 8 23 6 7 9, 16 24 25 6 7 10 14 24 25 5 11 13 20 26 3 4 5 6 8 9 10 22 25 26 27 AN3042 AN3075 AN3033 AN3067 AN3066 AN3036 XN2087 XN2095 AN3008 AN3095 AN3098 AN3021 AN3107 AN3025 AN3068 AN3096 AN3040 XN2091 UD4034 XN2108 XN2099 AN3126 AN3099 AN3064 UD4115 UD4032 AN3028 AN3045 AN3031 AN3074 UD5066 AN3090'N3029 AN3038 AN3051 AN3133 AN3043 UD5071 AN3092 UD5064 AN3089 AN3083 AN3134 AN3119 71970 73079 73130 61769 73366 63602 71965 70104 71758 5938D 5900D 71458 71808 63257 70287 70257 73367 71387 72009 73379 61638 71933 71956 72035 70190 62686 72474 71914 71389 73425 71780 73390 72439 71756 63949 71927 6450D 71938 63572 71198 62513 71809 73384 63442 46918 47612 46740'7193 44038 44649 39247 39371 44586 37527 38424 46740 44849 46819 45588 45296 44748 36125 41880 40563 42632 47186 47126 41718 30912 30303 41533 47621 44510 47607 43637 47681 43969 47099 47120 45963 37847 37852 44270 45818 44359 46523 45177 47161 Table 1 (Cont.)Row Column Current Assembly Channel ID Proj.EOC 9 Exposure 6 7 7 7 7 7 7 8 8 8 8 8 8 8 9 9 9 9 10 10 10 10 10 10 11 11 11 11 11 12 12 12 12 12 12 13 13 13 14 14 14 14 15 15 15 15 28 3 8 12 19 27 28 2 8 10 11 12 21 29 1 6 25 30 1 4 8 23 27 30 1 5 23 26 30 1 7 15 16 24 30 1 8 30 1 23 25 30 1 8 12 15 AN3130 XN2086 UD5070 AN3039 AN3125 AN3124 XN2094 AN3034 UD5072 AN3070 UD4025 UD5063 AN3027 AN3022 AN3032 AN3104 AN3085 AN3030-AN3076 UD4024 AN3079 AN3084 UD4022 AN3097 AN3100 AN3053 UD4031 AN3103 AN3049 AN3052 AN3069 AN3035 AN3007 AN3081 AN3120 AN3054 UD5065 AN3082 AN3080 UD4029 UD5013 AN3001 XN2084 UD5030 AN3041 UD5069 6012D 71300 71945 71789 71755 71376 71761 71757 70238 5881D 70279 71817 71437 72027 71942 72039 73394 71443 5809D 73124 63445 71391 73386 71400 73120 5898D 72038 73154 72024 71958 73116 71986 5960D 73111 73226 63427 61550 71447 5866D 73117 70110 71790 71936 71848 73108 63492 35556 36550 45874 45729 45584 41594 35989 45307 46115 37854 43736 44770 46213 47311 43959 47033 46329 44097 39001 31375 46813 47052 37823 47663 46830 39081 44572 39070 46828 46391 46028 45280 36559 37074 46857 45912 40884 34336 36350 30712 46305 45294 39297 45400 44889 46029 Table 1 (Cont.)Row Column Current Assembly I'Channel ID Proj.EOC 9 Exposure ,, 15 15., 15 16 16 19 23 30 1=4 16 16 16 16 16 16 16 16 16 17 17 17 17.17 17 17 18 18 18 18 18 19 19 19 19 19 19 19 19 19 19 19 20 20 20 20 20 12 15 16 19 20 21 24 25 30 1 10~12 19 21 29 30 1'22 23 30'10 11, 14 15 16 17 20 21 24 30 1 5 9 ll 12 16 6 16 7-16 10 16 11 AN3026 UD5035 XN2067 XN2066"UD5040 UD4016 UD4021 UD4143 UD5036 AN3020 UD5028 UD5025 AN3060 UD5022 UD4140 UD4003 UD4139 XN2100 AN3002 UD4144-UD4012 UD4134 UD4142 UDS026 AN3122 AN3058 UD5039 UD5031 UD5021 AN3112 AN3019 UD4005 UD5010 UD4039 AN3056 AN3078 UD4007 UD5024 UD4014 AN3023 AN3063 AN3086 AN3057 UD4033 UD4041 UDS004 72001 71983 73582 61972 62522 71904 73232 72042 73238 63956 71962 71141 71268 70252 71801 63953 73132 71959 62283 71434 71950 70167 6028D 61750 71928 73388 70011 73415 71799 71990 71852 73089 72034 71835 61741 71967 73426 61529 72018 5850D 62937 70047 5802D-71795 71923 71908 45348 45006 39887 33095 43137 32845 47418 32464 42577 45756 45397 46076 45592 42717 29988 47417 30540 33173 36432 30213 33116 30230 36462 42583 42349 45791 43890 43998 43411 45473 47231 33984 44953 32198 45434 45621 31688 44728 29767 37057 47021 44381 39070 30131-33693 45676 Table 1 (Cont.)Row Column Current Assembly Channel ID Proj.EOC 9 Exposure 20 20 20 20 20 20 20 20 21 21 21 21 21 21 21 21 21 21 21 21 21 21 22 22 22 22 2.2 22 22 23 15 16 20 22 24 26 29 30 1 2 8 10 12 14 15 16 17 19 21 23 29 30 1 6 11 13 20 25 30 23 23 23 23 23 24 24 24 24 24 24 24 24 15 17 21 25 29 3 4 7 8 11 12 16 19 23,8 23 10 23 14 UD5016 UD5037 UD4036 UD4023 UD5033 AN3111 UD5023 AN3091 AN3073 UD4042 AN3128 UD4038 UD4015 UD4027 UD4040 UD4035 UD4008 UD4013 UD4083 AN3016 UD4135 AN3116 AN3123 AN3050 UD4026 UD5014 UD4037"AN3093 AN3048 AN3011 UD5011 AN3131 UD4116 UD5018 UD4004 AN3121 UD5029 AN3061 XN2056 AN3037 UD4138 UD5017 UD5009 AN3055 UD4030 AN3077 71356 71830 73441 73614 70158 73135 73069 73112 72036 71943 72021 73403 5912D 71393 71786 71957 71907 71770 71953 71448 71975 63947 71991 71449 71778 71759 61931 73420 70272 60890 71930 72041 71392 61538 73444 71444 61773 73399 72023 72037 71334 63943 71913 73171 71308 71812 42790 42962 34195 39187 45086 47628 42591 46828 47663 46205 47002 31013 34227 30450 32216 47804 30224 27878 31549 46513 43694 47633 46059 35546 30170 44377 31023 47024 43959 48146 45838 46552 31006 45268 38303 46808 44513 47943 42227 41502 30007 45859 45563 46086 47347 45669 Table 1 (Cont.)Row Column Current Assembly Channel lD Proj.EOC, 9 Exposure'24 24 24 25 25 25 25 25 25 25 25'25 25 25 25 26 26 26 26 26 27'27 27 27 27 27 27 27 27 28 28 28 28 28 29 29 30 30 30 ,30 30 30 30 30 30 30 24 27 28 4 5 6 8 9 14 15-22 25 26 27 28 5'1 18 20 26 6 7 10 12 14 16 19.21 25 7 15 16 24 25 20 23 9 10 ll 12 13 14 15 16 17 18 UD4 13 6 AN3129 XN2068 AN3013 AN3102 AN3012 UD5020 AN3088 UD5008 UD4028 AN3094 AN3059 AN3065 AN3005 AN3006 AN3044 AN3087 UD5034 AN3105 AN3047 AN3101 AN3018 UD4011 UD4137 UD4006 UD5038 UD4141 UD4132 AN3108 XN2081 XN2073 XN2060 XN2078 AN3017 UD5032 AN3109 AN3127 AN3071 AN3132 AN3072 AN3114 AN3014 XN2065 XN2052 AN3015 AN3106 70103 71442 61682 71838 71753 5999D 71791 5905D 71377 73368 5852D 5868D 71976 73 15'3 71912 73422 61578 71771 70206 73133 61523 71431 71792 62501 71954 71960 71369 63950 71994 71390 71964 73416 61673-73139 70243 73121 70102 73131 71981 71788.5805D 71985 71921 61526 72014 5932D 30045 41286~42817 47089 36910 37819 44261 35518 46817 30426 38237 35158 39663.47029 47221.44510 47363 44582 47141 41869~47454 41309 30625 30375 31509 43 602.30376 ,30900 47321 36125 40563 33610.42327 47186 42458 47750 46819 35907 46882 47029 34826 44707 32884.32863 44802-37651 Table 1 (Cont.)Row Column Current Assembly Channel ID Proj.-EOC 9 Exposure 30 19 30 20 30 21 30 22 AN3110 AN3024 AN3115 AN3062 71773 71445 73227 71890 46884 47032 47512 46812 6 Figure 1 Cycle 9 Load Pattern Showing Assemblies with Reused Channels 1 2 4 5 6 7 8 9 10 11 12 13 14 15 2 3 4 5.'7 8 9 AH3032*10 AN3076>>11 AH3100*12 AH3052*13.AH3054*14 AN3080*15 XH2084>>16 XN2066>>17 AN3002" 18 AN3058*19 AN3019*20 AN3086*21 AH3073*22 AH3123*23 24 25 26 27 28 29 30 AH3034*UD6052.UD41'11 UD 5121 UD6057 UD6114 UD5054 UO6115 UD6002 UD5075 UD6012 UD6078 UD5085 UD4042*UD6079 AN3011*AN3038*XN2086>>UD6058 UD4122'MPS UD6041 WPS UD7068 WPS XH2024 XH2071 WPB UD7053 WPB UD 6015 WPB UD4071 UD6077 XH2056*AN3009 AH3051*AN3046 UD6053 WPB UD4024>>UD7005 UD4017 UD511'I UD4054 UD 5130 UD5040*UD4097 UD5086 UD4077 l$7031 UD4076 WPB UD6110 AH3037*AN3013*AH3031>>AH3133*UD6056 WPB UD7024 WPS AH3053*WPS UD 5127 WPS UD 7019 UD 7011 WPS UD5080 WPS AH3057*WPB UD7065 WPS UD6072 AH3102*AH3044*AN3040*AN3099*UD4146 AH3043*UD6112 UD5129 AN3104*LYV153 UD6037 UD6060 UD6036 UD5087 UD4062 UD 4016*UD 5134 UD6034 UD6080 UD6100 LYV156 AN3050*UD5078 UD6001 AN3012>>UD4145 AH3101*AN3118 XH2091*AN3064*UD6054 UD6120 UD4112 UD 5135 UD7089 WPS UD5126 Ak3069*UD7090 WPS UD4088 UD4021>>WPB UD7072 AN3010 UD5094 WPB UD7046 UD5102 un4138*UD6017 UD6067 AN3018*XH2081*AH3042*AN3068*uo6038 uo6113 uo4034*UD6075 WPB MPB UD7078 UD5071*AH3092*UD5070*UD7021 UD5072>>UD6061 UD6062 UD4128 AN3079*WPS UD4121 UD4117 UD5132'WPS UD5065*uo5055 UD4052 WPB UD5030*UO5007 UD5042 UD5019 UD4091'WPS UD5095 UD5039*UD5103 WPB UO4072 UD4033*AH3128*'WPS UD6021 UD4131 UD5011*UD6029 UD5017*UD7060 UD5020*AN3088*WPS UD7080 UD6111 WPB UD6073 UD4094 AN3113 UD6014 AH3127" AH3075>>AH3033*UD4018 UD5124 WPB UD6068 UD4115*UD7095 WPB AH3074*uo5o64>>uo6os7 WPB UD5058 AH3070>>UD4025*WPS UD4108 UD4045 WPS WPS UD4100 UD4047 UD5123 UD7020 UD7023 UD4113 WPB UD4061 UD5056 UO4143>>un5036*UD4144>>WPS UD7062 UD7047 UO4005*UD5010*WPB UO4041*UD4038*WPB'WPB UD4026*AH3131*UD4087'WPB UD5009*UD5076 UD6105 WPS AN30S7*UD4011*UD7054 WPS UD6055 UD4078 UD5081 AH3071*AH3132*Ak3067*AH3066*UD6069 UD6059 WPB UD7030 UD4114 WA6003'WPB UD5066*UD6013 UD6028 AN3039*UD7064 UD5063*UD5125 WPB UD5062 UD4048 UD7087 UD5131 UD7093 UO4043 UD6108 UD6103 UD4053 UD4104 WPB AN3041*UD6094 AH3020*UD6117 UD4012*WPB UD6022 UD4095 UD4101 UD6016 UD5004>>UD7001 UD4015*UD7010 WPS UD5014*UD5084.UD5079 AN3055*UD7083 UD6071 UD6035 WPS UD5082 UD4137*WA6001 WPS UD7013 UD6070 UD6076 AH3072*AH3114*AH3036*UD5093'WPB UD4032*WPB UD5061 WPB UD4118 WPS UD4107 WPB UD4099'WPB UD7079 UD4046 UD4102 UD7063'WPB UD4039*WPB UD4027*WPB UD4116*WPS I$5008*WPS UD4006*WPB UD5120 AH3Q'l4>>XH2087*UD6039 XH2025 UD5128 UD7075*UD4082 UD4051-UD5122 UD5005 UD4103 UD5057 AH3035*UD6026 UD4044 UD5069*UD5028*UD4098 UD6102 AH3056*UD5016*UD4040*UD5003 UD5018*UD4092 UD4028*UD7004 UD5077 Xk2073*UD6018 XH2065*1 2 16'17 18 4 5 6 19 20'1 22 8 9 10 11 23 24 25 26 12 13 27 28 14 29 15 30 1 XH2095*2 UD6066 3 XH2108*4 UD5068 5 UD7103 6 UD4093 7 UD4065.8 UD5116 9 UD5015 10 UD4119 11 UD5041 12 AH3007>>13 UD6020 14 UD4063 15 UD5112 16 UD5025*17 UO4080 18 UD61'16 19 AN3078*20 UD5037>>21 UO4035*22 UD5006 23 UD5002 24 UD4030*25 UD4049 26 UD7081 27 un5038*28 XN2060*29 UD6031'0 XH2052*16 AN3008*UD5083 WPS UD4055 WPS UD5044 WPS UD4126 WPB UD4129 WPB UD4120 WPS UD7033 UD4057 UD4084 UD7088 WPB UD4007*WPS uo4008*WPB UD4004>>WPB UD5096 WPB UD4002 WPB UD5059 AN3015*17 AN3095*UD6050 UD7027 WA6004 UD5115 UD6049 UD7077 UD5108 UD5045 UO7091 UD7105 UD6042 UD4070 WPS UD6074 UD6081 WPS UD4068 UD6009 UD7084 UD7097 UD5100 UD5107 UD7050 UD6005 UD5034" WA6002 UD7035 UD6091 AH3106*.18 AH3098*AH3021*UD6063 UD5052 WPB UD6019 UD4127 UD7067 WPS AN3090*UD6047 UD6010 AN3125*UD5109 UD5049 UD4073 WPS UD4124 UD4010 WPS UD5117 UD4001 UD4064 UD5051 UD6107 UD7032 UD4106 WPB AN3026*UD5074 AN3060*UO5022*UD4134*WPB UD6027 UD7100 UD4079 UD5024*UD5106 UD4036>>UD4013*WPB.WPB UD4037*UD5001 UD4090 AH3077" UD5104 UD6024 UD6082 WPB AH3105*UD4141*UD7052 WPB UD6090 uo6033 UD5032>>AN3110>>AH3024*19 20 AN3025*UD6065 UD4059 WPS UD7082 AN3089*UD7043 UD6064 UD 4130 WPB UD4123 WPS UD5053 WPS UD5012 UD5027 WPS uo5031*WPB UD4023*WPB UD 4133 UD6023 UD7055 AH3094*UD7026'WPB UD4074 UD6004 AN3062*AN3107*UD4058 WPS UD4105 WPS UD5073 WPS AN3027*WPS UD4020 WPS UD4019 UD7099 UD4050 UD4009 UD 4140*UD 4142*UD7056 UO4014*WPB uo4083*WPB AN3121*WPB UD5097 WPB UD 4132*WPS UD4085 AN3115*AH3096>>UD6119 XH2099>>UO6096 AH3028*WPS UO6046 UD5043 UD6101 UD5050 ,UD4109 UD5091 UD5046 UO6044 UD7025 AN3084*WPS" uo4031*Uo5118 UD5119 AH3081*UD5067 UD7022 UD4029*WPS UD5035*UD4125 UD5060 UD4003*UD4081'WPB UD5021*UD7016 UD5090 AN3023*UD4075 UD5033>>AH3016>>WPB UD6032 UD7096 UD5089 UD5088 UD5099 UD4136*UO5098 UD6007 WPS UD6083 UD6051 AN3117 UD6095-XH2078*AN3109*21-22 23 24 AN3126*AH3045*UO4147 AH3029*Ak3083*AN3134*UD6099 UD6040 UD5048 WPS AN3085>>UD7018 LYV155 WPS UD6011 AN3103*UD6045 WPB UD6104 UD5113 UD5013*WPB UD4056 UD7102 UD4139", UD7066 UD5136'WPB UD6006 UD5105 UD6093 WPB UD6118 AN3111*LYV154 WPB AN3093*UD7058 UD5029*WPB UD6003 UD6084 AH3059*AH3065*UD4148 AN3047" AN3108*AN3017*25 26 AN3119*AN3130*AH3124*XN2094*UD6097 UD6109 WPB UD4096 UD4022*WPB UD7040 UD6048 UD4066'WPB UD5133 UD7094 UD4069 WPS UD5114 XH1090 UD5101 XH1141 UD4067 WPS UD5092 UD7057 UD4086'MPS UD7106 UD6085 UD4060 WPS WPS UD4089 UD6086 l$6089 AN3129*XN2068*AH3005*AN3006*27 28 Ak3022*UD6043 UD4110 UD5047 UD6025 UD 6106 UD 5110 UD6098 UD6030 UD5026>>UD6008 UD6088-UD5023*UD 4135*UD6092 AH3061*AN3030*AN3097>>AH3049*AH3120*AN3082*AN3001*XN2067*XH2100*AH3122*AN3112*AH3063*AN3091*AH3116*AH3048*30 WPS are fresh 9x9-9X assemblies loaded in Cycle 9>>Assemblies with Reused Channels
COUNTY      OF BENTON        )
I. G. C. SORENSEN, being duly sworn, subscribe to and say that I am the Manager, Regulatory Programs for the WASHINGTON PUBLIC POWER SUPPLY SYSTEM, the applicant herein; that I have the full authority to execute this oath; that I have reviewed the foregoing; and that to'he best of my knowledge, information, and belief the statements made in it are true.
DATE       Z HWMdyd'C/Ayy&             , 1993 G. C. Sor nsen, Manager Regulatory Programs On this date personally appeared before me G. C, SORENSEN, to me known to be the individual who executed the foregoing instrument, and acknowledged that he signed the same as his free act and deed for the uses and purposes herein mentioned.
GIVEN under my hand and seal this   ~tday of                                     1993 ~
M(
otary Public in and for the STATE OF WASHINGTON Residing at Kennewick Washin ton My 2       y y   2*Ay   ~A'I 2
 
Table  1 I
Reused Channels, Assemblies',     and Projected EOC 9 Exposures Current                          Proj.      EOC 9 Row Column     Assembly             Channel ID     Exposure 1   9          AN3042                71970          46918 1   10        AN3075                73079          47612 1   11        AN3033                73130          46740'7193 1   12        AN3067                61769 1   13        AN3066                73366          44038 1   14        AN3036                63602          44649 1   15        XN2087                71965          39247 1   16,,      XN2095                70104          39371 1   17        AN3008                71758          44586 1   18        AN3095                5938D          37527 1   19        AN3098                5900D          38424 1   20        AN3021                71458          46740 1   21        AN3107                71808          44849 1    22        AN3025                63257          46819 2    8          AN3068                70287          45588 2    23        AN3096                70257          45296 3   6          AN3040                73367          44748
: 3. 7          XN2091                71387          36125 3   9,        UD4034                72009          41880 3    16        XN2108                73379          40563 3    24        XN2099                61638        42632 3    25        AN3126                71933          47186 4   6          AN3099                71956          47126 4   7          AN3064                72035          41718 4   10        UD4115                70190          30912 4   14        UD4032                62686          30303 4   24        AN3028                72474          41533 4    25        AN3045                71914          47621 5   5         AN3031                71389          44510 5   11        AN3074                73425          47607 5   13        UD5066                71780          43637 5   20        AN3090'N3029 73390          47681 5    26                              72439          43969 6   3          AN3038                71756          47099 6   4          AN3051                63949          47120 6   5          AN3133                71927          45963 6   6         AN3043                6450D          37847 6   8          UD5071                71938          37852 6   9          AN3092                63572          44270 6   10        UD5064                71198          45818 6   22         AN3089                62513          44359 6   25        AN3083                71809          46523 6   26         AN3134                73384          45177 6   27         AN3119                63442          47161
 
Table 1 (Cont.)
Current                  Proj . EOC 9 Row  Column Assembly      Channel ID  Exposure 6    28    AN3130        6012D      35556 7    3    XN2086        71300      36550 7    8    UD5070        71945      45874 7    12    AN3039        71789      45729 7    19    AN3125        71755      45584 7    27    AN3124        71376      41594 7    28    XN2094        71761      35989 8    2    AN3034        71757      45307 8    8    UD5072        70238      46115 8    10    AN3070        5881D      37854 8    11    UD4025        70279      43736 8    12    UD5063        71817      44770 8    21    AN3027        71437      46213 8    29    AN3022        72027      47311 9    1    AN3032        71942      43959 9    6    AN3104        72039      47033 9    25    AN3085        73394      46329 9    30    AN3030-        71443      44097 10  1    AN3076        5809D      39001 10  4    UD4024        73124      31375 10  8    AN3079        63445      46813 10  23    AN3084        71391      47052 10  27    UD4022        73386      37823 10  30    AN3097        71400      47663 11  1     AN3100        73120      46830 11  5    AN3053        5898D      39081 11  23    UD4031        72038      44572 11  26    AN3103        73154      39070 11  30    AN3049        72024      46828 12  1    AN3052        71958      46391 12  7     AN3069        73116      46028 12  15    AN3035        71986      45280 12  16    AN3007        5960D      36559 12   24    AN3081        73111      37074 12   30    AN3120        73226      46857 13   1    AN3054        63427      45912 13   8    UD5065        61550      40884 13   30    AN3082        71447      34336 14   1    AN3080        5866D      36350 14   23    UD4029        73117      30712 14   25    UD5013        70110      46305 14   30    AN3001        71790      45294 15   1    XN2084        71936      39297 15   8    UD5030        71848      45400 15   12    AN3041        73108      44889 15   15    UD5069        63492      46029
 
Table 1 (Cont.)
Current                  Proj. EOC 9 Row Column      Assembly      'Channel ID  Exposure I
  ,, 15  19      AN3026          72001    45348 15  23      UD5035          71983    45006
.,  15   30     XN2067          73582    39887 16  1 =    XN2066          61972    33095 16  4      "UD5040          62522    43137 16  6      UD4016          71904    32845 16  7-     UD4021          73232    47418 16  10      UD4143          72042    32464 16  11      UD5036          73238    42577 16  12      AN3020          63956    45756 16  15      UD5028          71962    45397 16  16      UD5025          71141    46076 16  19      AN3060          71268    45592 16  20      UD5022          70252    42717 16  21      UD4140          71801    29988 16  24      UD4003          63953    47417 16  25      UD4139          73132    30540 16  30      XN2100          71959    33173 17  1      AN3002          62283    36432 17  10  ~  UD4144          71434    30213 17  12      -UD4012          71950    33116 17 .
19      UD4134          70167    30230 17  21      UD4142          6028D    36462 17  29      UDS026          61750    42583 17  30      AN3122          71928    42349 18  1'      AN3058          73388    45791 18            UD5039          70011    43890 18  22      UD5031          73415    43998 18  23  '
UD5021          71799    43411 18  30      AN3112          71990    45473 19          AN3019          71852    47231 19  10      UD4005          73089    33984 19  11,      UD5010          72034    44953 19  14      UD4039          71835    32198 19  15     AN3056          61741    45434 19  16     AN3078          71967    45621 19   17      UD4007          73426    31688 19   20      UD5024          61529    44728 19   21      UD4014          72018    29767 19   24      AN3023          5850D    37057 19   30      AN3063          62937    47021 20   1      AN3086          70047    44381 20   5      AN3057          5802D-    39070 20                            71795    30131-20 20 ll 9
12 UD4033 UD4041 UDS004 71923 71908 33693 45676
 
Table 1 (Cont. )
Current                  Proj . EOC 9 Row  Column Assembly      Channel ID  Exposure 20    15    UD5016        71356      42790 20   16   UD5037        71830      42962 20    20    UD4036        73441      34195 20    22    UD4023        73614      39187 20    24    UD5033        70158      45086 20    26    AN3111        73135      47628 20    29    UD5023        73069      42591 20    30    AN3091        73112      46828 21    1    AN3073        72036      47663 21    2    UD4042        71943      46205 21    8    AN3128        72021      47002 21    10    UD4038        73403      31013 21    12    UD4015        5912D      34227 21    14    UD4027        71393      30450 21    15    UD4040        71786      32216 21    16    UD4035        71957      47804 21    17    UD4008        71907      30224 21    19    UD4013        71770      27878 21    21    UD4083        71953      31549 21    23    AN3016        71448      46513 21    29    UD4135        71975      43694 21    30    AN3116          63947      47633 22    1    AN3123        71991      46059 22    6    AN3050        71449      35546 22    11    UD4026        71778      30170 22    13    UD5014        71759      44377 2.2  20    UD4037          61931      31023 22    25  "AN3093        73420      47024 22    30    AN3048        70272      43959 23          AN3011          60890      48146 23,8        UD5011        71930      45838 23    10    AN3131        72041      46552 23    14    UD4116        71392      31006 23    15    UD5018          61538      45268 23    17    UD4004          73444      38303 23    21    AN3121        71444      46808 23    25    UD5029          61773      44513 23    29    AN3061        73399      47943 24    3    XN2056        72023      42227 24    4    AN3037        72037      41502 24    7    UD4138        71334      30007 24    8    UD5017          63943      45859 24    11    UD5009        71913      45563 24   12   AN3055        73171      46086 24    16   UD4030        71308      47347 24    19   AN3077        71812      45669
 
Table 1 (Cont.)
Current                  Proj  . EOC, 9 Row  Column  Assembly      Channel lD  Exposure
  '24   24     UD4 13 6      70103        30045 24   27    AN3129        71442        41286    ~
24   28    XN2068        61682        42817 25   4     AN3013        71838        47089 25  5      AN3102        71753        36910 25  6      AN3012        5999D        37819 25  8     UD5020        71791        44261 25  9      AN3088        5905D        35518 25  14     UD5008        71377        46817 25  15-    UD4028        73368        30426 25  22    AN3094        5852D        38237
  '25  25    AN3059        5868D        35158 25  26    AN3065        71976        39663.
25  27    AN3005        73 15'3      47029 25  28    AN3006        71912        47221.
26  5      AN3044        73422        44510 61578        47363
          '1 26          AN3087 26  18    UD5034        71771        44582 26  20    AN3105        70206        47141 26  26    AN3047        73133        41869  ~
27  6      AN3101        61523        47454
'27    7      AN3018        71431        41309 27  10    UD4011        71792        30625 27  12    UD4137        62501        30375 27  14    UD4006        71954        31509 27  16    UD5038        71960        43 602.
27  19    UD4141        71369        30376 27  .21    UD4132        63950        ,30900 27  25    AN3108        71994        47321 28  7      XN2081        71390        36125 28  15    XN2073        71964        40563 28  16    XN2060        73416        33610.
28  24    XN2078        61673-        42327 28  25     AN3017        73139        47186 29  20    UD5032        70243        42458 29  23    AN3109        73121        47750 30  9      AN3127        70102        46819 AN3071        73131        35907 30 30
  ,30 ll 10 12 AN3132 AN3072 71981 71788.
46882 47029 30   13    AN3114        5805D        34826 30   14    AN3014        71985        44707 30   15    XN2065        71921        32884    .
30   16    XN2052        61526        32863 30   17    AN3015        72014        44802 30   18    AN3106        5932D      -
37651
 
Table 1 (Cont.)
Current                  Proj . -EOC 9 Row  Column Assembly      Channel ID  Exposure 30  19    AN3110        71773      46884 30  20   AN3024        71445      47032 30  21    AN3115        73227      47512 30   22    AN3062        71890      46812 6


UNITED STATES NUCLEAR REGULATORY COMMISSION OFFICE OF NUCLEAR REACTOR REGULATION WASHINGTON, D.C.20555 November 10, 1992 NRC INFORMATION NOTICE 92-74: POWER OSCILLAT 8NS AT WASHINGTON NUCLEAR POWER~'NIT,.2 Addressees All holders of operating licenses or construction permits for boiling-water reactors (BWRs).~Pur ose The U.S.Nuclear Regulatory Commission (NRC)is issuing this information notice to alert addressees to a recent event involving power oscillations in an operating region where instability had not been specifically predicted.
Figure  1 Cycle 9 Load Pattern Showing Assemblies with Reused Channels 1        2              4        5        6        7        8      9      10       11      12      13      14      15 AH3042* AH3075>> AH3033* Ak3067* AH3066* AH3036* XH2087*
It is expected that recipients'will review the information for applicability to their facilities and consider actions, as appropriate, to avoid similar problems.However, suggestions contained in this information notice are not NRC requirements; therefore, no specific action or written response is required.~Back round On March 9, 1988, a thermal hydraulic instability event occurred at LaSalle Unit 2.The NRC discussed this event in Information Notice 88-39,"LaSalle Unit 2 Loss of Recirculation Pumps with Power Oscillation Event," and Bulletins 88-07 and 88-07, Supplement 1,"Power Oscillations in Boiling Water Reactors." In the first bulletin, the NRC requested licensees to establish procedures and give training to reactor operators to enable them to recognize oscillations and to take appropriate actions.In the supplement, the NRC requested licensees.
2                                                                AN3068* uo6038 UD4018 UD5124      UD6069  UD6059  UD5093  UD6039 3                                              AN3040* XH2091* uo6113 uo4034* WPB          UD6068  WPB      UD7030  'WPB    XH2025 4                                              AN3099* AN3064* UD6075 WPB          UD4115* UD7095  UD4114 WA6003 UD4032* UD5128 5.'                                    AH3031>> UD4146 UD6054 MPB            UD7078 WPB      AH3074* 'WPB    UD5066* WPB      UD7075 AN3038* AH3051* AH3133* AH3043* UD6120 UD5071* AH3092* uo5o64>> uo6os7          UD6013 UD6028 UD5061 UD4082 7                    XN2086>> AN3046 UD6056 UD6112 UD4112 UD5070* UD7021 WPB                UD5058  AN3039* UD7064 WPB        UD4051-8            AH3034* UD6058 UD6053 WPB        UD5129 UD 5135 UD5072>> UD6061 AH3070>> UD4025*        UD5063* UD5125 UD4118 UD5122 9 AH3032* UD6052 . UD4122 WPB          UD7024 AN3104* UD7089 UD6062 UD4128 WPS              UD4108  WPB      UD5062 WPS      UD5005 10 AN3076>> UD41'11 'MPS      UD4024>> WPS      LYV153 WPS          AN3079* WPS      UD4045 WPS      UD4048 UD7087 UD4107 UD4103 11 AH3100* UD 5121    UD6041 UD7005 AH3053* UD6037 UD5126 UD4121 UD4117 WPS                  UD4100  UD5131 UD7093 WPB        UD5057 12 AH3052* UD6057 WPS        UD4017 WPS        UD6060 Ak3069* UD5132 'WPS          UD4047 UD5123  UO4043 UD6108 UD4099 AH3035*
to implement the General Electric (GE)Interim Recommendations for Stability Actions, designated the Interim Corrective Actions (ICA).GE defined the exclusion regions on the power/flow map in which, with varying probability, instability might be expected.Three regions were defined in which operation was to be avoided (immediate exit if entered)or limited (e.g., when required during startup).These regions were based on'operating or test experience for reactors with GE fuel.The exclusion regions for new fuel designs were to be reevaluated and justified based on any applicable operating experience, calculated changes in core decay ratio using NRC-approved methodology, and/or core decay ratio measurements.
: 13. AH3054* UD6114 UD7068 UD511'I UD 5127 UD6036 UD7090 UD5065* uo5055 UD7020 UD7023                UD6103 UD4053 'WPB        UD6026 14 AN3080* UD5054 WPS        UD4054 WPS        UD5087 WPS          UD4052 WPB      UD4113 WPB      UD4104 WPB      UD7079 UD4044 15 XH2084>> UO6115 XH2024 UD 5130 UD 7019 UD4062 UD4088 UD5030* UO5007 UD4061 UD5056                  AN3041* UD6094 UD4046 UD5069*
Since.the LaSalle event in 1988, the NRC and the BWR Owners'roup (BWROG)have conducted extensive analyses and reviews of various aspects of stability while developing long-term solutions to augment or replace the ICA.On March 18, 1992, the BWROG sent a letter (BWROG-92030) to BWROG members 9211040206 IN 92-74 November 10, 1992 Page 2 of 5 transmitting"Implementation Guidance for Stability Interim Corrective Actions." In this letter, the BWROG emphasized the need for caution when operating near the exclusion regions.The BWROG also recommended reexamining procedures and training to reflect uncertainties in the definition of exclusion region boundaries.
16 XN2066>> UD6002 XH2071 UD5040* UD 7011 UD 4016* UD4021>> UD5042 UD5019 UO4143>> un5036*              AH3020* UD6117 UD4102 UD5028*
'l~Descri tion of Circumstances
17 AN3002" UD5075 WPB        UD4097 WPS        UD 5134  WPB        UD4091 'WPS      UD4144>> WPS    UD4012* WPB      UD7063 UD4098 18 AN3058* UD6012 UD7053 UD5086 UD5080 UD6034 UD7072 UD5095 UD5039* UD7062 UD7047                    UD6022 UD4095 'WPB        UD6102 19 AN3019* UD6078 WPB        UD4077 WPS        UD6080 AN3010 UD5103 WPB            UO4005* UD5010* UD4101 UD6016 UD4039* AH3056*
~g On August 15, 1992, Washington Nuclear Power Unit 2 (WNP-2)experienced power oscillations during startup.The event occurred early in cycle 8 operation.
20 AN3086* UD5085 UD 6015 l$ 7031 AH3057* UD6100 UD5094 UO4072 UD4033* WPB                  UO4041* UD5004>> UD7001 WPB        UD5016*
During, cycle, 8, the licensee had two previous startups without incident.The reactor core consisted primarily of Siemens fuel, with about 74 percent of this fuel in 8x8 fuel assemblies and about 25 percent in 9x9 fuel assemblies,.and with the remainder of the core consisting of various lead test assemblies.
21 AH3073* UD4042* WPB        UD4076 WPB        LYV156 WPB          AH3128* 'WPS    UD4038* WPB    UD4015* UD7010 UD4027* UD4040*
The 9x9 fuel assembly used in WNP-2, designated 9x9-9x, has a higher flow-resistance-than the 8x8 fuel assembly with a difference of about 10 percent in pressure drop..These 9x9 fuel assemblies were loaded during cycles 7 and 8.J About 33 hours before the event, the licensee commenced a controlled power reduction from full power to 5-percent power to repair a valve packing leak in the drywell.After completing the repairs, the licensee began'a return to full power: The licensee increased reactor power to about 34 percent and then held it at that level for 3 hours to perform turbine bypass valve tests and control rod drive system timing tests.The recirculation syst'm was operated with flow control valves (FCVs)full open and pumps at slow speed.After completing the tests, the operators continued the restart up the (approximately) 30-percent flow line to about 36-percent power (Figure 1).This is at a power above the recirculation pump cavitation region.The operators then began closing one of the two FCVs in preparation for shifting the associated recirculation pump to fast speed.During this change, in which power and flow decreased along the 76-percent rod.line to a power/flow of about 34/27 percent, the operators observed power oscillations first on the average power range monitors (APRHs)and then by local power range monitors (LPRHs)downscale indications.
22 AH3123* UD6079 UD4071 WPB            UD7065 AN3050* UD7046 UD6021 UD4131 'WPB            UD4026* WPS      UD5014* WPB      UD5003 23            AN3011* UD6077 UD6110 WPS        UD5078 UD5102 UD5011* UD6029 AH3131* UD4087          UD5084 . UD5079 UD4116* UD5018*
Upon recognizing the power oscillations, the plant operators manually initiated a reactor scram.Post-event review indicated that the 2-second-period oscillations were in-phase (core-wide) and had grown to a peak-to-peak ampl'itude of about 25 percent of rated power.Host of the oscillation amplitude'iricrease occurred in an interval of about 1 minute with the oscillations continuing at the limiting (maximum)amplitude for an additional minute before scram.The,oscillations occurred while the reactor was operating at a power about 4'percent of rated power below the lower.exclusion region boundary line (the nominal 80-percent rod line).During later review, the licensee found no indication that fuel had failed because of the event.
24                    XH2056* AH3037* UD6072 UD6001 un4138* UD5017* UD7060 'WPB              UD5009* AN3055* UD7083 WPS        UD4092 25                    AN3009 AN3013* AH3102* AN3012>> UD6017 UD5020* AN3088* UD5076 UD6105            UD6071 UD6035 I$ 5008* UD4028*
IN 92-74 November 10, 1992 Page 3-'of 5 The NRC sent an Augmented Inspection Team (AIT)to the site to determine the possible causes and relevant facts of this event.The AIT concluded that the primary cause of the oscillations was very skewed radial and bottom peaked axial power distributions in the reactor (1.92 radial peaking factor and 1.62 core average axial peaking factor).These power distributions resulted from (1)the control rod pattern that the shift technical advisor selected for increasing the power and shifting the recirculation pump, speed, and (2)the relationship of this control rod pattern to the specific WNP-2 cycle 8 core fuel loading configuration.
26                                      AH3044* UD4145 UD6067 WPS            UD7080 WPS      AN30S7* WPS      UD5082 WPS      UD7004 27                                              AH3101* AN3018* UD6111 WPB          UD4011* UD7054  UD4137* WA6001 UD4006* UD5077 28                                              AN3118 XH2081* UD6073 UD4094 WPS            UD6055  WPS      UD7013 WPB      Xk2073*
These rod patterns were primarily directed towards achieving the target full power configuration and did not consider stability concerns.The AIT also found, by analyses using the LAPUR code, that a contributor to the oscillations was the core loading, consisting of a mixed core with unbalanced flow characteristics between the new 9x9-9x fuel and the old 8x8 fuel: The analyses indicated that a full core of the 9x9-9x fuel would be significantly less stable than the old 8x8 fuel, and that the mixed.core was.less stable'than a fully loaded core of either fuel type.The analyses also indicated that while the oscillations would be in-phase (core-wide), as observed in the event, the out-of-phase (regional) instability boundary would be very close to the in-phase boundary (Figure 1).The AIT found that small changes in operating conditions could have resulted in out-of-phase oscillations, which would have been more difficult for the APRH system to detect.WNP-2 has a Siemens Advanced Neutron Noise Analysis (ANNA)monitor, a stability monitor required by technical specifications only if the licensee intends to enter the lower exclusion region.Since the licensee did not intend to enter the exclusion region during this startup, the ANNA monitor was not put into the observation mode, although it was gathering data which was used later to confirm stability calculations performed after the event.The licensee successfully restarted the unit after implementing the following restrictions for maintaining the limits on rod withdrawal patterns and power distribution in the low flow regions of concern.0 The licensee analyzed the control rod patterns for stability before startup, and the operator could not.change these patterns without analysis and review.The calculated maximum total peaking factor.was less than 3.4.
29                                                                  AN3113 UD6014 UD4078 UD5081      UD6070 UD6076 UD5120 UD6018 30                                                                          AH3127" AH3071* AH3132* AH3072* AH3114* AH3Q'l4>> XH2065*
IN 92-74 November 10, 1992 Page 4 of 5 The calculated core average axial peaking factor was less than 1.45.~The Hinimum Critical Power Ratio was greater than 2.2.The licensee analyzed the conditions at FCV closure and found a decay ratio of less than 0.5.The recirculation pump was shifted to fast speed with the reactor power less than 33 percent and the feedwater temperature greater than 146.I'C-(295'F).The licensee continuously used the ANNA monitor when the reactor was operating above 25 percent power and below 50 percent flow.Further detailed description of the event can be found in the AIT Inspection Report No.50-397/92-30.
1        2              4        5        6                  8      9      10      11      12      13      14      15 16      '17    18      19      20    '1          22        23      24      25      26      27      28      29      30 1 XH2095*    AN3008* AN3095* AH3098* AH3021* AN3107* AN3025*
Discussion The WNP-2 power oscillation event indicates that the boundaries of the ICA regions, or modifications approved for various reactor technical specifications, do not necessarily encompass all stability limits Instability may occur beyond these boundaries if the reactor is operated with configurations outside those used to define the boundaries.
2 UD6066    UD5083  UD6050  UD6063    UD5052  UD4058  UD6065    AH3096>>
This event presented direct evidence that the following factors can be significant contributors to the possibility of unstable operation.
3 XH2108*    WPS    UD7027  WPB      UD6019  WPS      UD4059    UD6119 XH2099>> AN3126*
4 UD5068    UD4055  WA6004  UD4127    UD7067  UD4105  WPS        UO6096 AH3028* AH3045*
5 UD7103    WPS    UD5115  WPS      AN3090* WPS      UD7082    WPS      UO6046 UO4147  AH3029*
6 UD4093    UD5044  UD6049  UD6047    UD6010  UD5073  AN3089*    UD5043 UD6101 Ak3083*    AN3134* AN3119* AN3130*
7 UD4065. WPS    UD7077  AN3125* UD5109    WPS      UD7043    UD5050 ,UD4109 UD6099    UD6040 AH3124* XN2094*
8 UD5116    UD4126  UD5108  UD5049 UD4073    AN3027* UD6064      UD5091 UD5046 UD5048    WPS    UD6097 UD6109 Ak3022*
9 UD5015    WPB    UD5045  WPS      UD4124  WPS      UD 4130    UO6044 UD7025 AN3085>>    UD7018  WPB      UD4096  UD6043  AN3030*
10 UD4119    UD4129  UO7091  UD4010 WPS        UD4020  WPB        AN3084* WPS "    LYV155  WPS    UD4022* WPB      UD4110  AN3097>>
11 UD5041    WPB    UD7105  UD5117 UD4001    WPS      UD4123    uo4031* Uo5118 UD6011    AN3103* UD7040 UD6048    UD5047  AH3049*
12  AH3007>>  UD4120  UD6042  UD4064 UD5051    UD4019  WPS        UD5119 AH3081* UD6045    WPB    UD4066 'WPB      UD6025  AH3120*
13  UD6020  WPS    UD4070  UD6107 UD7032    UD7099  UD5053    UD5067 UD7022 UD6104    UD5113  UD5133  UD7094  UD 6106  AN3082*
14  UD4063  UD7033  WPS    UD4106 WPB        UD4050  WPS        UD4029* WPS      UD5013* WPB    UD4069  WPS    UD 5110  AN3001*
15  UD5112  UD4057  UD6074  AN3026* UD5074    UD4009  UD5012    UD5035* UD4125 UD4056    UD7102 UD5114    XH1090  UD6098  XN2067*
16  UD5025*  UD4084  UD6081  AN3060* UO5022*  UD 4140* UD5027    UD5060 UD4003* UD4139", UD7066 UD5101    XH1141  UD6030  XH2100*
17 UO4080    UD7088  WPS    UD4134* WPB      UD 4142* WPS        UD4081 'WPB      UD5136  'WPB    UD4067  WPS    UD5026>>  AH3122*
18 UD61'16    WPB    UD4068  UD6027 UD7100    UD7056 uo5031*      UD5021* UD7016 UD6006    UD5105 UD5092    UD7057  UD6008  AN3112*
19 AN3078*    UD4007* UD6009  UD4079 UD5024*    UO4014* WPB        UD5090 AN3023* UD6093    WPB    UD4086  'MPS    UD6088-  AH3063*
20 UD5037>>    WPS    UD7084  UD5106 UD4036>>    WPB      UD4023*    UD4075 UD5033>> UD6118    AN3111* UD7106  UD6085  UD5023*  AN3091*
21 UO4035*    uo4008* UD7097  UD4013* WPB.     uo4083*  WPB        AH3016>> WPB      LYV154  WPB    UD4060  WPS    UD 4135* AH3116*
22 UD5006    WPB    UD5100  WPB      UD4037* WPB      UD 4133    UD6032 UD7096 AN3093*    UD7058 WPS      UD4089  UD6092  AH3048*
23 UD5002    UD4004>> UD5107  UD5001 UD4090    AN3121* UD6023      UD5089 UD5088 UD5029*    WPB    UD6086  l$ 6089 AH3061*
24 UD4030*    WPB    UD7050  AH3077" UD5104    WPB      UD7055    UD5099 UD4136* UD6003    UD6084 AN3129*  XN2068*
25 UD4049    UD5096 UD6005  UD6024 UD6082    UD5097  AH3094*    UO5098 UD6007 AH3059*    AH3065* AH3005* AN3006*
26 UD7081    WPB    UD5034" WPB      AH3105* WPB      UD7026    WPS      UD6083 UD4148  AN3047" 27 un5038* UD4002    WA6002  UD4141* UD7052    UD 4132* 'WPB      UD6051 AN3117 AN3108*
28 XN2060* WPB        UD7035  WPB      UD6090  WPS      UD4074    UD6095 - XH2078* AN3017*
29 UD6031 UD5059      UD6091  uo6033 UD5032>> UD4085 UD6004          AN3109*
  '0    XH2052* AN3015* AH3106*. AN3110>> AH3024* AN3115* AN3062*
16      17      18      19      20      21      -22        23      24      25      26      27      28              30 WPS  are fresh 9x9-9X assemblies    loaded  in Cycle  9
>> Assemblies    with Reused Channels
 
UNITED STATES NUCLEAR REGULATORY COMMISSION OFFICE OF NUCLEAR REACTOR REGULATION WASHINGTON, D.C. 20555 November 10, 1992 NRC INFORMATION NOTICE    92-74:  POWER  OSCILLAT 8NS AT WASHINGTON NUCLEAR  POWER
                              ~ 'NIT,.2 Addressees All holders of operating licenses or construction permits for boiling-water reactors (BWRs).
~Pur ose The U.S. Nuclear Regulatory Commission      (NRC) is issuing this information notice to alert addressees to a recent event involving power oscillations in an operating region where instability had not been specifically predicted.         It is expected that recipients'will review the information for applicability to their facilities and consider actions, as appropriate, to avoid similar problems. However, suggestions contained in this information notice are not NRC requirements;  therefore, no specific action or written response is required.
~Back round On  March 9, 1988, a thermal hydraulic instability event occurred at LaSalle Unit 2. The NRC discussed this event in Information Notice 88-39, "LaSalle Unit 2 Loss of Recirculation Pumps with Power Oscillation Event," and Bulletins 88-07 and 88-07, Supplement 1, "Power Oscillations in Boiling Water Reactors." In the first bulletin, the NRC requested licensees to establish procedures and give training to reactor operators to enable them to recognize oscillations and to take appropriate actions. In the supplement, the NRC requested licensees. to implement the General Electric (GE) Interim Recommendations for Stability Actions, designated the Interim Corrective Actions (ICA). GE defined the exclusion regions on the power/flow map in which, with varying probability, instability might be expected. Three regions were defined in which operation was to be avoided (immediate exit      if entered) or limited (e.g., when required during startup). These regions were based on
'operating or test experience for reactors with GE fuel. The exclusion regions for new fuel designs were to be reevaluated and justified based on any applicable operating experience, calculated changes in core decay ratio using NRC-approved methodology, and/or core decay ratio measurements.        Since .the LaSalle event in 1988, the NRC and the BWR Owners'roup (BWROG) have conducted extensive analyses and reviews of various aspects of stability while developing long-term solutions to augment or replace the ICA. On March 18, 1992, the BWROG sent a letter (BWROG-92030) to BWROG members 9211040206
 
IN 92-74 November 10, 1992 Page 2  of 5 transmitting "Implementation Guidance for Stability Interim Corrective Actions." In this letter, the BWROG emphasized the need for caution when operating near the exclusion regions. The BWROG also recommended reexamining procedures and training to reflect uncertainties in the definition of exclusion region boundaries.
                                    'l ~
Descri tion of Circumstances            ~
g On  August 15, 1992, Washington Nuclear Power Unit 2 (WNP-2) experienced power oscillations during startup. The event occurred early in cycle 8 operation.
During, cycle, 8, the licensee had two previous startups without incident. The reactor core consisted primarily of Siemens fuel, with about 74 percent of this fuel in 8x8 fuel assemblies and about 25 percent in 9x9 fuel assemblies,
.and with the remainder of the core consisting of various lead test assemblies.
The 9x9 fuel assembly used in WNP-2, designated 9x9-9x, has a higher flow-resistance -than the 8x8 fuel assembly with a difference of about 10 percent in pressure drop.. These 9x9 fuel assemblies were loaded during cycles 7 and 8.
J About 33 hours before the event, the licensee commenced a controlled power reduction from full power to 5-percent power to repair a valve packing leak in the drywell. After completing the repairs, the licensee began'a return to full power: The licensee increased reactor power to about 34 percent and then held  it at that level for 3 hours to perform turbine bypass valve tests and control rod drive system timing tests. The recirculation syst'm was operated with flow control valves (FCVs) full open and pumps at slow speed.
After completing the tests, the operators continued the restart up the (approximately) 30-percent flow line to about 36-percent power (Figure 1).
This is at a power above the recirculation pump cavitation region. The operators then began closing one of the two FCVs in preparation for shifting the associated recirculation pump to fast speed. During this change, in which power and flow decreased along the 76-percent rod. line to a power/flow of about 34/27 percent, the operators observed power oscillations first on the average power range monitors (APRHs) and then by local power range monitors (LPRHs) downscale indications. Upon recognizing the power oscillations, the plant operators manually initiated a reactor scram. Post-event review indicated that the 2-second-period oscillations were in-phase (core-wide) and had grown to a peak-to-peak ampl'itude of about 25 percent of rated power.
Host of the oscillation amplitude'iricrease occurred in an interval of about 1 minute with the oscillations continuing at the limiting (maximum) amplitude for an additional minute before scram. The,oscillations occurred while the reactor was operating at a power about 4'percent of rated power below the lower. exclusion region boundary line (the nominal 80-percent rod line).
During later review, the licensee found no indication that fuel had failed because of the event.
 
IN 92-74 November 10, 1992 Page 3-'of 5 The  NRC  sent  an Augmented    Inspection Team (AIT) to the site to determine the possible causes and      relevant  facts of this event. The AIT concluded that the primary    cause  of the  oscillations   was very skewed radial and bottom peaked axial power distributions in the reactor (1.92 radial peaking factor and 1.62 core average axial peaking factor). These power distributions resulted from (1) the control rod pattern that the shift technical advisor selected for increasing the power and shifting the recirculation pump, speed, and (2) the relationship of this control rod pattern to the specific WNP-2 cycle 8 core fuel loading configuration. These rod patterns were primarily directed towards achieving the target full power configuration and did not consider stability    concerns.
The AIT    also found, by analyses using the LAPUR code, that a contributor to the oscillations was the core loading, consisting of a mixed core with unbalanced flow characteristics between the new 9x9-9x fuel and the old 8x8 fuel: The analyses indicated that a full core of the 9x9-9x fuel would be significantly less stable than the old 8x8 fuel, and that the mixed .core was.
less stable'than a fully loaded core of either fuel type. The analyses also indicated that while the oscillations would be in-phase (core-wide), as observed in the event, the out-of-phase (regional) instability boundary would be very close to the in-phase boundary (Figure 1). The AIT found that small changes in operating conditions could have resulted in out-of-phase oscillations, which would have been more difficult for the APRH system to detect.
WNP-2 has    a Siemens  Advanced Neutron Noise Analysis (ANNA) monitor, a stability monitor required        by technical specifications only  if  the licensee intends to enter the lower exclusion region. Since the licensee did not intend to enter the exclusion region during this startup, the ANNA monitor was not put into the observation mode, although        it  was gathering data which was used later to confirm stability calculations performed after the event.
The licensee successfully restarted the unit after implementing the following restrictions for maintaining the limits on rod withdrawal patterns and power distribution in the low flow regions of concern.
The   licensee analyzed the control rod patterns for stability before startup,    and the operator could not.change these patterns without analysis and review.
0    The   calculated    maximum  total  peaking factor.was less than 3.4.
 
IN 92-74 November 10, 1992 Page 4 of  5 The  calculated core average axial peaking factor    was  less than 1.45.
~    The Hinimum    Critical Power Ratio was greater than 2.2.
The  licensee analyzed the conditions at FCV closure and found a decay ratio of less  than 0.5. The recirculation pump was shifted to fast speed with the reactor power less than 33 percent and the feedwater temperature greater than 146. I 'C -(295 'F).
The  licensee continuously used the ANNA monitor when the reactor      was operating above 25 percent power and below 50 percent flow.
Further detailed description of the event can     be found   in the AIT Inspection Report No. 50-397/92-30.
Discussion The WNP-2 power   oscillation event indicates that the boundaries of the ICA regions, or modifications approved for various reactor technical specifications, do not necessarily encompass all stability limits Instability may occur beyond these boundaries     if the reactor is operated with configurations outside those used to define the boundaries. This event presented direct evidence that the following factors can be significant contributors to the possibility of unstable operation.
Power distributions involving extremely skewed radial and axial peaking factors can induce unstable operation even in regions or with operating conditions not otherwise considered susceptible to oscillations.
Power distributions involving extremely skewed radial and axial peaking factors can induce unstable operation even in regions or with operating conditions not otherwise considered susceptible to oscillations.
Core loading patterns involving a mixture of fuel types with differing flow resistances can contribute to instability.
Core loading   patterns involving a mixture of fuel types with differing flow resistances can contribute to instability.                     0 Reactors with two-speed recirculation pumps and   FCVs can hinder   stability because   of the narrow range of operation between   pump cavitation   regions and possible instability regions.
0 Reactors with two-speed recirculation pumps and FCVs can hinder stability because of the narrow range of operation between pump cavitation regions and possible instability regions.The event also indicates the value of operating a stability monitor.The ANNA monitor could have given the operators information that instability was iqminent, prompting them to alter operations to avoid the oscillations.
The event also indicates the value of operating a stability monitor . The       ANNA monitor could have given the operators information that instability was iqminent, prompting them to alter operations to avoid the oscillations.
IN 92-74'November 10, 1992 Page 5,of 5 This information notice requires no specific action or written response.If you have any questions about the information in this notice, please contact one of the technical contacts listed below or the appropriate Office of Nuclear Reactor Regulation (NRR)project manager.II~Brian K.Grimes, Director Division of Operating.
 
Reactors Support Office of Nuclear Reactor Regulation Technical contacts: Howard Richings, NRR (301)504-2888 Peter C.Wen, NRR (301)504-2832 Attachments:
IN 92-74
1.Figure 1.Best-Estimate Lines of Constant Decay Ratio=l.0 for Actual Conditions of WNP-2 8/15/1992 Event, Assuming Constant Power Distribution 2.List of Recently Issued NRC Information Notices Attachment 1 IN 92-74 November 10, 1992 Page 1 of 1 WNP-2 8/15 STARTUP CONDITIONS LAPUR-consta est i ma%nt out-ed lin of-pha e of se DR=70 60 100$rod line+50 45 40~sos rod line:----t APU¹est-i.constant in maCeci--I-'I-ne--of-
                                                              'November 10, 1992 Page 5,of 5 This information notice requires no specific action or written response.     If you have any questions   about the information in this notice, please contact one of the technical contacts listed below or the appropriate Office of Nuclear Reactor Regulation (NRR) project manager.
-phase DR=1 6%rod one 25 20 20 25 30 35 40 45 Core Flow ($of Rated)55 60 Figure L,, Best-estimate lines of constant decay ratio 1.0 for actual conditions of 8/15 event, assuming constant power distribution Attachment 2 IN 92-74 November 10, 1992 Page 1 of 1 LIST OF RECENTLY ISSUED NRC INFORMATION NOTICES n ormatlon Notice No.Subject ate o Issuance Issued to 92-61, Supp.1 92-73 Loss of High Head Safety Injection Removal of A Fuel Element from A Re-search Reactor Core While Critical 11/06/92 11-04/92 All holders of OLs or CPs for nuclear power reactors.All holders of OLs or CPs for nuclear power reactors.92-59, Rev.1 Horizontally-Installed Motor-Operated Gate Valves 11/04/92-All holders of OLs or CPs for nuclear power reactors.92-72 Employee Training and Shipper Registration Requirements for Trans-porting Radioactive Materials 10/28/92 All U.S.Nuclear Regulatory Commission Licensees.
II ~
91-64, Supp.1 92-71 Site Area Emergency Resulting from A Loss of Non-Class lE Uninterruptible Power Supplies Partial Plugging of Suppression Pool Strainers At A Foreign BWR 10/07/92 09/30/92 All holders of OLs or CPs for nuclear power reactors.All holders of OLs or CPs for nuclear.power reactors: 92-70 Westinghouse Motor-Operated 09/25/92 Valve Performance Data Supplied to Nuclear Power Plant Licensees All holders of OLs or CPs for nuclear power reactors.92-69 91-'29, Supp.1 Water Leakage from Yard Area Through Conduits Into Buildings Deficiencies Identified During Electrical Dis-tribution System Func-tional Inspections 09/22/92 09/14/92 All holders of OLs or CPs for nuclear power reactors.All holders of OLs or CPs for nuclear power reactors.perat>ng 1cense CP=Construction Permit UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C.20555-0001 FIRST CLASS MAIL POSTAGE AND FEES PAID USNRC PERMIT NO.G-67 OFFICIAL BUSINESS PENALTY FOR PRIVATE USE,$300.120555, p pg9-56 I US fgR CO I R-g=.l...1.C.O I CY1FB11$1.CH IE'F".OI V...OF INFO SUP SVCS u~F-P'=r'*-""'"'"""'-'"--'---
Brian K. Grimes, Director Division of Operating. Reactors Support Office of Nuclear Reactor Regulation Technical contacts:   Howard Richings,   NRR (301) 504-2888 Peter C. Wen, NRR (301) 504-2832 Attachments:
RECOR*S ,WASJQfJGQON..
: 1. Figure 1. Best-Estimate Lines of Constant Decay Ratio=l.0 for Actual Conditions of WNP-2 8/15/1992 Event, Assuming Constant Power Distribution
,.OC 30555 PRINTED ON RECYCLEO PAPER}}
: 2. List of Recently Issued   NRC Information Notices
 
Attachment 1 IN 92-74 November 10, 1992 Page 1 of 1 WNP-2   8/15     STARTUP CONDITIONS LAPUR-est     i ma% ed  line of consta nt out- of-pha se           DR=
70 60 100$ rod   line 50
                                                        ~
  +
sos rod   line 45 40                              :----t APU¹ est-i. maCeci-- I-'I-ne--of-constant    in phase     DR=1 6% rod one 25 20 20     25         30       35       40       45                 55    60 Core Flow ( $   of Rated   )
Figure L,, Best-estimate     lines of constant decay ratio 1.0 for actual conditions of 8/15 event, assuming constant power distribution
 
Attachment   2 IN 92-74 November 10, 1992 Page 1 of 1 LIST OF RECENTLY ISSUED NRC INFORMATION NOTICES n ormatlon                                           ate  o Notice No.                 Subject                 Issuance     Issued to 92-61,           Loss   of High Head               11/06/92     All holders of OLs or CPs Supp. 1        Safety Injection                                for nuclear power reactors.
92-73            Removal    of A Fuel              11-04/92    All holders of OLs or CPs Element from A Re-                              for nuclear power reactors.
search Reactor Core While    Critical 92-59,           Horizontally-Installed             11/04/92   -
All holders of OLs or CPs Rev. 1          Motor-Operated Gate                            for nuclear power reactors.
Valves 92-72             Employee   Training   and         10/28/92     All U.S. Nuclear Regulatory Shipper Registration                            Commission Licensees.
Requirements for Trans-porting Radioactive Materials 91-64,           Site Area    Emergency            10/07/92    All holders of OLs or CPs Supp. 1       Resulting from     A Loss                       for nuclear power reactors.
of Non-Class lE Uninterruptible     Power Supplies 92-71            Partial Plugging of               09/30/92     All holders of OLs or CPs Suppression Pool                                for nuclear. power reactors:
Strainers At A Foreign BWR 92-70             Westinghouse Motor-Operated       09/25/92     All holders of OLs or CPs Valve Performance Data                          for nuclear power reactors.
Supplied to Nuclear Power Plant Licensees 92-69             Water Leakage from Yard           09/22/92     All holders of OLs or CPs Area Through Conduits                          for nuclear power reactors.
Into Buildings 91-'29,          Deficiencies Identified          09/14/92      All holders of OLs or CPs Supp. 1        During Electrical Dis-                          for nuclear power reactors.
tribution    System Func-tional Inspections perat>ng   1cense CP = Construction Permit
 
UNITED STATES                                                           FIRST CLASS MAIL NUCLEAR REGULATORY COMMISSION                                                     POSTAGE AND FEES PAID WASHINGTON, D.C. 20555-0001                                                             USNRC PERMIT NO. G-67 OFFICIAL BUSINESS PENALTY FOR PRIVATE USE, $ 300
                                      .120555,   pg9-56 I R-g=.l...1.C.O I CY1FB11$ 1 p
I  US  fgR  CO
                                      .OI V...OF INFO SUP SVCS
                                      .CH IE'F" u~F-P'=r'*-""'"'"" "'-'"--'---
RECOR *S
                                      ,WASJQfJGQON..         ,   . OC   30555 PRINTED ON RECYCLEO PAPER}}

Latest revision as of 07:32, 4 February 2020

Suppls Listed Responses to NRC Bulletin 90-002, Loss of Thermal Margin Caused by Channel Box Bow, Effect on Cycle 9 Operation.Requests NRC Approval for Plan to Reuse Channel Boxes During Cycle 9
ML17289B147
Person / Time
Site: Columbia Energy Northwest icon.png
Issue date: 02/02/1993
From: Sorensen G
WASHINGTON PUBLIC POWER SUPPLY SYSTEM
To:
NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
GO2-93-024, GO2-93-24, IEB-90-002, IEB-90-2, TAC-M76354, TAC-M82920, NUDOCS 9302120132
Download: ML17289B147 (22)
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Text

ACCELERATE'D DOCUMENT DIS'103BUTION SYSTEM REGULATORY INFORMATION DISTRIBUTION SYSTEM (RIDS)

ACCESSION NBR:9302120132 DOC.DATE: 93/02/02 NOTARIZED: YES DOCKET N FACIL:50-397 WPPSS Nuclear Project, Unit 2, Washington Public Powe 05000397 AUTH. NAME AUTHOR AFFILIATION

, SORENSEN,G.C. Washington Public Power Supply System RECIP.NAME RECIPIENT AFFILIATION Document Contxol Branch (Document Control Desk)

SUBJECT:

Suppls listed responses to NRC Bulletin 90-002, "Loss of Thermal Margin Caused by Channel Box Bow," effect on Cycle 9 operation. Requests NRC approval for plan to reuse channel boxes during Cycle 9.

DISTRIBUTION CODE: IE38D COPIES RECEIVED:LTR ENCL SIZE:

TITLE: NRC Bulletin 90-002, Loss of Thermal Margin Caused by Channel Box Bow NOTES:

RECIPIENT COPIES RECIPIENT COPIES ID CODE/NAME LTTR ENCL ID CODE/NAME LTTR ENCL

. PD5 LA 1 0 PD5 PD 1 1 CLIFFORDF J 1 1 INTERNAL: AEOD/DOA 1 1 AEOD/DSP/TPAB 1 -1 NRR FIENO,D 1 1 NRR LONGFW PD31 1 1 NRR/DET/EMEB 7E 1 1 NRR/DOEA/OEAB11 1 1 NRR/DOEA/OGCBll 1 1 NRR/DREP/PEPB9D 1 1 NRR/Dggf 8E2 1 1 NRR/PMAS/ILRB12 1 1 GREG FILED 02 1 1 RES/DSIR/EIB 1 1 RGN5 FILE 01 1 1 EXTERNAL: NRC PDR 1 1 NSIC 1 1 NOTE TO ALL"RIDS" RECIPIENTS PLEASE HELP US TO REDUCE WASTE! CONTACT THE DOCUMENT CONTROL DESK, ROOM Pl-37 (EXT. 504-2065) TO ELIMINATEYOUR NAME FROM DISTRIBUTION LISTS FOR DOCUMENTS YOU DON'T NEED!

TOTAL NUMBER OF COPIES REQUIRED: LTTR 18 ENCL 17

A WASHINGTON PUBLIC POWER SUPPLY SYSTEM P.O. Bax 968 ~ 3000 George Wasbtngton Way ~ Rtcbland, Wasbtngton 99352496'8 ~ (509) 372-5000 February 2, 1993 G02-93-024 Docket No. 50-397 U.S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, D.C. 20555

Subject:

%NP-2, OPERATING LICENSE NPF-21 RESPONSE TO NRC BULLETINNO. 90-02: "LOSS OF THERMAL MARGIN.CAUSED BY CHANNEL BOX BOW", EFFECT ON CYCLE 9 OPERATION (TAC No. M82920)

References:

1. NRC Bulletin No. 90-02, March 20, 1990, "Loss of Thermal Margin Caused by Channel Box Bow"
2. Letter, G02-90-075, April 13, 1990, GC Sorensen (SS) to of WNP-2 Cycle 6 Reload Submittal and Response to NRC USNRC,'Modification Bulletin No. 90-02: Loss of Thermal margin Caused by Channel Box Bow"
3. ANF-524(P)(A), Rev. 2, Supplements 1 and 2, November 1990, "Advanced Nuclear Fuels Corporation Critical Power Methodology for Boiling Water Reactors"
4. Letter, G02-90-162, September 28; 1990, GC Sorensen (SS) to USNRC, "Final Response to NRC Bulletin No. 90-02: Loss of Thermal Margin

. Caused by Channel Box Bow"

5. Letter, G02-91-037, February 25, 1991, GC Sorensen (SS) to USNRC, "Request for Additional Information Regarding NRC Bulletin 90-02, Loss of Thermal Margin Caused by Channel Box Bow"
6. Letter, April 22, 1991, PL Eng (NRC) to GC Sorensen (SS), "Evaluation of Response to NRC Bulletin No. 90-02: Loss of Thermal Margin Caused by Channel Box Bow (TAC No."'76354)"
7. Letter, G02-92-048, February 25, 1992, GC Sorensen to USNRC, "Response to NRC Bulletin No. 90-02: Loss of Thermal Margin Caused by Channel Box Bow, Effect on Cycle 8 Operation"
8. Letter, June 15, 1992, WM Dean (NRC) to GC Sorensen, "Evaluation of Response to NRC Bulletin No. 90-02: Loss of Thermal Margin Caused by Channel Box Bow (TAC No. M82920)"

g)Oc;t h 9302i20l32 9302020500039'7 PDR ADOCK PDR

Page Two RESPONSE TO NRC BULLETINNO. 90-02: "LOSS, OF THERMAL MARGIN CAUSED BY CHANNEL BOX BOW", EFFECT ON CYCLE 9 OPERATION (TAC No. M82920)

Reference,1 requested that licensees reusing channel boxes verify that current Minimum Critical Power Ratio (MCPR) Technical Specification operating and safety limits are met. All affected licensees were requested to advise the NRC of the number and location of such channel boxes and to describe the methods and associated data base used to account for the effects of channel box bow during reuse of channel boxes to ensure conformance with the CPR limits.

The Supply System responded to this bulletin in References 2, 4, 5 and 7. Reference 6 provided WNP-2 the NRC evaluation of the issues for Cycle 7, and Reference 8 for Cycle 8. Reference 6

'required that the reuse of channel boxes in future cycles be evaluated on a cycle specific basis.

This letter responds to those requirements for WNP-2 Cycle 9. The effect of potential channel box bow on CPR limits was evaluated in the Cycle 9 design.

WNP-2, a C-lattice BWR, is less susceptible than a D-lattice BWR to the phenomena of and effects from channel box bow. The Supply System, aware of the potential problems associated with channel box bow, has had a channel management program in place since initial operation of WNP-2. The WNP-2.channel management program consists of data collection on channel operating history and actual measurement of channel distortion as a function of channel.

operation. The current goal of the channel management program is to use a channel box for a single assembly lifetime. To achieve this goal, the Supply System is currently putting new channels on new fuel. During the transition the Supply System will discharge channels predicted

, to achieve a target burnup of approximately 50 GWd/MTU in a cycle or perform an analysis to justify continued use. Reference 4 discusses the basis for the selection of the exposure target and analytical methodology.

In Cycle 8, 291 of the 764 channels in the WNP-2 core were reused channels. In Cycle 9 there will be 232 reused channels. Twenty-four (24) channels will be replaced at the end of Cycle 8 because their exposures at the end of Cycle 9 are expected to exceed 50 GWd/MTU. These channels will be replaced with less exposed channels from the spent fuel pool. Each of the 24 replacement channels has been measured for channel box bow and bulge and meets the pre-determined acceptance criteria of Reference 4. At the end of Cycle 9, the peak reused channel exposure is predicted to be less than 49 GWd/MTU.

~d/

EXPOSURE RANGE UANTITY 27 - 34 42-34 - 41 42 41-48 148

Page Three

~ ~

RESPONSE TO NRC BULLETINNO. 90-02: "LOSS OF THERMAL MARGIN CAUSED BY CHANNEL BOX BOW", EFFECT ON CYCLE 9 OPERATION (TAC No. M82920)

. Beginning with Cycle 7, the effects of channel box bow were addressed in WNP-2 reload design using the approved Siemens Power Corporation (SPC) methodology for determining the Safety Limit Minimum Critical Power Ratio (SLMCPR) (Reference 3). The SPC data incorporated in the SPC methodology has been reviewed previously by the NRC (including WNP-2 measured data) and along with the methodology has been approved by the NRC (Reference 3). The SLMCPR established for Cycle 9 operation of WNP-2 will include the effects of channel box bow as analyzed by this methodology.

During Cycle 9, 232 reused channels will be in the WNP-2 core, The planned location coordinates for each reused channel for Cycle 9 are given in Table 1. The location of each reused channel is also indicated on the attached Figure 1 (core map) by assembly number. The appropriate channel number for each assembly number can be determined from Table 1. A total of 76 of the reused channels will be located face adjacent to new fuel assemblies. Experience has 'shown that limiting assemblies are almost always once burned assemblies and, potentially at the end of a long cycle, fresh assemblies can be limiting. However, the precise location of limiting assemblies during Cycle 9 will be dependent upon the actual operating experience. A reused channel could, therefore, be adjacent to a limiting assembly at some ti'me during Cycle.

9 operation. The probability of this occuring is recognized and taken'into account in calculation of the SLMCPR using the SPC methodology.

Channel distortion (bow + bulge), magnitude and direction, is directly dependent upon the location history of the channels. The channels that will have the largest estimated exposure at end of cycle are channels 60890 and 73399. The channels will reside in core location 23,2 and 23,29 respectively (row and column coordinates from the upper left corner as shown in Figure 1). The Supply System analytical model predicts a maximum calculated total distortion for these channels to be less than 105 mils. Total distortions for the other reused channels in WNP-2 shown in Table 1 are predicted to be less than this value.

The anticipated effect of maximum channel bow is accounted for in the MCPR operating limit by modification of the SLMCPR, which is a part of the MCPR operating limit. The WNP-2 SLMCPR is established through statistical consideration of measurement and calculational uncertainties associated with the thermal hydraulic state of the reactor using design basis radial, axial and local power distributions and considering fuel channel bow. Reference 3 discusses vendor MCPR safety limit methodology and describes in detail how channel bow effects are incorporated irito, the MCPR safety limit. The effects of channel bow increase the WNP-2 Cycle 9 MCPR safety limit by about 0.02, P

Page Fqur RESPONSE TO NRC BULLETINNO. 90-02: "LOSS OF THERMAL MARGIN CAUSED BY CHANNEL BOX BOW", EFFECT ON CYCLE 9 OPERATION (TAC No. M82920)

In accordance with the requirements of IEB 90-02 and Reference 6, the Supply System is requesting NRC approval for this plan for the reuse of channel boxes during Cycle 9. The channels are to be loaded into the core during the spring 1993 refueling outage, scheduled for 45 days beginning in April. Therefore, prompt NRC approval of this submittal would be appreciated.

Sincerely, G. C. Sorensen, Manager Regulatory Programs (Mail Drop PE20)

JDF:bw Attachments: 1; Table 1; Reused Channels, Assemblies And Projected Exposure

2. Figure 1; Cycle 9 Load Pattern Showing Assemblies with Reused, Channels CC: JB Martin - NRC RV NS Reynolds - Winston & Strawn JD Clifford - NRC DL Williams - BPA/399 NRC Site Inspector - 901A

STATE OF WASHINGTON )

Subject:

Res onse to IEB 90-02

)

COUNTY OF BENTON )

I. G. C. SORENSEN, being duly sworn, subscribe to and say that I am the Manager, Regulatory Programs for the WASHINGTON PUBLIC POWER SUPPLY SYSTEM, the applicant herein; that I have the full authority to execute this oath; that I have reviewed the foregoing; and that to'he best of my knowledge, information, and belief the statements made in it are true.

DATE Z HWMdyd'C/Ayy& , 1993 G. C. Sor nsen, Manager Regulatory Programs On this date personally appeared before me G. C, SORENSEN, to me known to be the individual who executed the foregoing instrument, and acknowledged that he signed the same as his free act and deed for the uses and purposes herein mentioned.

GIVEN under my hand and seal this ~tday of 1993 ~

M(

otary Public in and for the STATE OF WASHINGTON Residing at Kennewick Washin ton My 2 y y 2*Ay ~A'I 2

Table 1 I

Reused Channels, Assemblies', and Projected EOC 9 Exposures Current Proj. EOC 9 Row Column Assembly Channel ID Exposure 1 9 AN3042 71970 46918 1 10 AN3075 73079 47612 1 11 AN3033 73130 46740'7193 1 12 AN3067 61769 1 13 AN3066 73366 44038 1 14 AN3036 63602 44649 1 15 XN2087 71965 39247 1 16,, XN2095 70104 39371 1 17 AN3008 71758 44586 1 18 AN3095 5938D 37527 1 19 AN3098 5900D 38424 1 20 AN3021 71458 46740 1 21 AN3107 71808 44849 1 22 AN3025 63257 46819 2 8 AN3068 70287 45588 2 23 AN3096 70257 45296 3 6 AN3040 73367 44748

3. 7 XN2091 71387 36125 3 9, UD4034 72009 41880 3 16 XN2108 73379 40563 3 24 XN2099 61638 42632 3 25 AN3126 71933 47186 4 6 AN3099 71956 47126 4 7 AN3064 72035 41718 4 10 UD4115 70190 30912 4 14 UD4032 62686 30303 4 24 AN3028 72474 41533 4 25 AN3045 71914 47621 5 5 AN3031 71389 44510 5 11 AN3074 73425 47607 5 13 UD5066 71780 43637 5 20 AN3090'N3029 73390 47681 5 26 72439 43969 6 3 AN3038 71756 47099 6 4 AN3051 63949 47120 6 5 AN3133 71927 45963 6 6 AN3043 6450D 37847 6 8 UD5071 71938 37852 6 9 AN3092 63572 44270 6 10 UD5064 71198 45818 6 22 AN3089 62513 44359 6 25 AN3083 71809 46523 6 26 AN3134 73384 45177 6 27 AN3119 63442 47161

Table 1 (Cont.)

Current Proj . EOC 9 Row Column Assembly Channel ID Exposure 6 28 AN3130 6012D 35556 7 3 XN2086 71300 36550 7 8 UD5070 71945 45874 7 12 AN3039 71789 45729 7 19 AN3125 71755 45584 7 27 AN3124 71376 41594 7 28 XN2094 71761 35989 8 2 AN3034 71757 45307 8 8 UD5072 70238 46115 8 10 AN3070 5881D 37854 8 11 UD4025 70279 43736 8 12 UD5063 71817 44770 8 21 AN3027 71437 46213 8 29 AN3022 72027 47311 9 1 AN3032 71942 43959 9 6 AN3104 72039 47033 9 25 AN3085 73394 46329 9 30 AN3030- 71443 44097 10 1 AN3076 5809D 39001 10 4 UD4024 73124 31375 10 8 AN3079 63445 46813 10 23 AN3084 71391 47052 10 27 UD4022 73386 37823 10 30 AN3097 71400 47663 11 1 AN3100 73120 46830 11 5 AN3053 5898D 39081 11 23 UD4031 72038 44572 11 26 AN3103 73154 39070 11 30 AN3049 72024 46828 12 1 AN3052 71958 46391 12 7 AN3069 73116 46028 12 15 AN3035 71986 45280 12 16 AN3007 5960D 36559 12 24 AN3081 73111 37074 12 30 AN3120 73226 46857 13 1 AN3054 63427 45912 13 8 UD5065 61550 40884 13 30 AN3082 71447 34336 14 1 AN3080 5866D 36350 14 23 UD4029 73117 30712 14 25 UD5013 70110 46305 14 30 AN3001 71790 45294 15 1 XN2084 71936 39297 15 8 UD5030 71848 45400 15 12 AN3041 73108 44889 15 15 UD5069 63492 46029

Table 1 (Cont.)

Current Proj. EOC 9 Row Column Assembly 'Channel ID Exposure I

,, 15 19 AN3026 72001 45348 15 23 UD5035 71983 45006

., 15 30 XN2067 73582 39887 16 1 = XN2066 61972 33095 16 4 "UD5040 62522 43137 16 6 UD4016 71904 32845 16 7- UD4021 73232 47418 16 10 UD4143 72042 32464 16 11 UD5036 73238 42577 16 12 AN3020 63956 45756 16 15 UD5028 71962 45397 16 16 UD5025 71141 46076 16 19 AN3060 71268 45592 16 20 UD5022 70252 42717 16 21 UD4140 71801 29988 16 24 UD4003 63953 47417 16 25 UD4139 73132 30540 16 30 XN2100 71959 33173 17 1 AN3002 62283 36432 17 10 ~ UD4144 71434 30213 17 12 -UD4012 71950 33116 17 .

19 UD4134 70167 30230 17 21 UD4142 6028D 36462 17 29 UDS026 61750 42583 17 30 AN3122 71928 42349 18 1' AN3058 73388 45791 18 UD5039 70011 43890 18 22 UD5031 73415 43998 18 23 '

UD5021 71799 43411 18 30 AN3112 71990 45473 19 AN3019 71852 47231 19 10 UD4005 73089 33984 19 11, UD5010 72034 44953 19 14 UD4039 71835 32198 19 15 AN3056 61741 45434 19 16 AN3078 71967 45621 19 17 UD4007 73426 31688 19 20 UD5024 61529 44728 19 21 UD4014 72018 29767 19 24 AN3023 5850D 37057 19 30 AN3063 62937 47021 20 1 AN3086 70047 44381 20 5 AN3057 5802D- 39070 20 71795 30131-20 20 ll 9

12 UD4033 UD4041 UDS004 71923 71908 33693 45676

Table 1 (Cont. )

Current Proj . EOC 9 Row Column Assembly Channel ID Exposure 20 15 UD5016 71356 42790 20 16 UD5037 71830 42962 20 20 UD4036 73441 34195 20 22 UD4023 73614 39187 20 24 UD5033 70158 45086 20 26 AN3111 73135 47628 20 29 UD5023 73069 42591 20 30 AN3091 73112 46828 21 1 AN3073 72036 47663 21 2 UD4042 71943 46205 21 8 AN3128 72021 47002 21 10 UD4038 73403 31013 21 12 UD4015 5912D 34227 21 14 UD4027 71393 30450 21 15 UD4040 71786 32216 21 16 UD4035 71957 47804 21 17 UD4008 71907 30224 21 19 UD4013 71770 27878 21 21 UD4083 71953 31549 21 23 AN3016 71448 46513 21 29 UD4135 71975 43694 21 30 AN3116 63947 47633 22 1 AN3123 71991 46059 22 6 AN3050 71449 35546 22 11 UD4026 71778 30170 22 13 UD5014 71759 44377 2.2 20 UD4037 61931 31023 22 25 "AN3093 73420 47024 22 30 AN3048 70272 43959 23 AN3011 60890 48146 23,8 UD5011 71930 45838 23 10 AN3131 72041 46552 23 14 UD4116 71392 31006 23 15 UD5018 61538 45268 23 17 UD4004 73444 38303 23 21 AN3121 71444 46808 23 25 UD5029 61773 44513 23 29 AN3061 73399 47943 24 3 XN2056 72023 42227 24 4 AN3037 72037 41502 24 7 UD4138 71334 30007 24 8 UD5017 63943 45859 24 11 UD5009 71913 45563 24 12 AN3055 73171 46086 24 16 UD4030 71308 47347 24 19 AN3077 71812 45669

Table 1 (Cont.)

Current Proj . EOC, 9 Row Column Assembly Channel lD Exposure

'24 24 UD4 13 6 70103 30045 24 27 AN3129 71442 41286 ~

24 28 XN2068 61682 42817 25 4 AN3013 71838 47089 25 5 AN3102 71753 36910 25 6 AN3012 5999D 37819 25 8 UD5020 71791 44261 25 9 AN3088 5905D 35518 25 14 UD5008 71377 46817 25 15- UD4028 73368 30426 25 22 AN3094 5852D 38237

'25 25 AN3059 5868D 35158 25 26 AN3065 71976 39663.

25 27 AN3005 73 15'3 47029 25 28 AN3006 71912 47221.

26 5 AN3044 73422 44510 61578 47363

'1 26 AN3087 26 18 UD5034 71771 44582 26 20 AN3105 70206 47141 26 26 AN3047 73133 41869 ~

27 6 AN3101 61523 47454

'27 7 AN3018 71431 41309 27 10 UD4011 71792 30625 27 12 UD4137 62501 30375 27 14 UD4006 71954 31509 27 16 UD5038 71960 43 602.

27 19 UD4141 71369 30376 27 .21 UD4132 63950 ,30900 27 25 AN3108 71994 47321 28 7 XN2081 71390 36125 28 15 XN2073 71964 40563 28 16 XN2060 73416 33610.

28 24 XN2078 61673- 42327 28 25 AN3017 73139 47186 29 20 UD5032 70243 42458 29 23 AN3109 73121 47750 30 9 AN3127 70102 46819 AN3071 73131 35907 30 30

,30 ll 10 12 AN3132 AN3072 71981 71788.

46882 47029 30 13 AN3114 5805D 34826 30 14 AN3014 71985 44707 30 15 XN2065 71921 32884 .

30 16 XN2052 61526 32863 30 17 AN3015 72014 44802 30 18 AN3106 5932D -

37651

Table 1 (Cont.)

Current Proj . -EOC 9 Row Column Assembly Channel ID Exposure 30 19 AN3110 71773 46884 30 20 AN3024 71445 47032 30 21 AN3115 73227 47512 30 22 AN3062 71890 46812 6

Figure 1 Cycle 9 Load Pattern Showing Assemblies with Reused Channels 1 2 4 5 6 7 8 9 10 11 12 13 14 15 AH3042* AH3075>> AH3033* Ak3067* AH3066* AH3036* XH2087*

2 AN3068* uo6038 UD4018 UD5124 UD6069 UD6059 UD5093 UD6039 3 AN3040* XH2091* uo6113 uo4034* WPB UD6068 WPB UD7030 'WPB XH2025 4 AN3099* AN3064* UD6075 WPB UD4115* UD7095 UD4114 WA6003 UD4032* UD5128 5.' AH3031>> UD4146 UD6054 MPB UD7078 WPB AH3074* 'WPB UD5066* WPB UD7075 AN3038* AH3051* AH3133* AH3043* UD6120 UD5071* AH3092* uo5o64>> uo6os7 UD6013 UD6028 UD5061 UD4082 7 XN2086>> AN3046 UD6056 UD6112 UD4112 UD5070* UD7021 WPB UD5058 AN3039* UD7064 WPB UD4051-8 AH3034* UD6058 UD6053 WPB UD5129 UD 5135 UD5072>> UD6061 AH3070>> UD4025* UD5063* UD5125 UD4118 UD5122 9 AH3032* UD6052 . UD4122 WPB UD7024 AN3104* UD7089 UD6062 UD4128 WPS UD4108 WPB UD5062 WPS UD5005 10 AN3076>> UD41'11 'MPS UD4024>> WPS LYV153 WPS AN3079* WPS UD4045 WPS UD4048 UD7087 UD4107 UD4103 11 AH3100* UD 5121 UD6041 UD7005 AH3053* UD6037 UD5126 UD4121 UD4117 WPS UD4100 UD5131 UD7093 WPB UD5057 12 AH3052* UD6057 WPS UD4017 WPS UD6060 Ak3069* UD5132 'WPS UD4047 UD5123 UO4043 UD6108 UD4099 AH3035*

13. AH3054* UD6114 UD7068 UD511'I UD 5127 UD6036 UD7090 UD5065* uo5055 UD7020 UD7023 UD6103 UD4053 'WPB UD6026 14 AN3080* UD5054 WPS UD4054 WPS UD5087 WPS UD4052 WPB UD4113 WPB UD4104 WPB UD7079 UD4044 15 XH2084>> UO6115 XH2024 UD 5130 UD 7019 UD4062 UD4088 UD5030* UO5007 UD4061 UD5056 AN3041* UD6094 UD4046 UD5069*

16 XN2066>> UD6002 XH2071 UD5040* UD 7011 UD 4016* UD4021>> UD5042 UD5019 UO4143>> un5036* AH3020* UD6117 UD4102 UD5028*

17 AN3002" UD5075 WPB UD4097 WPS UD 5134 WPB UD4091 'WPS UD4144>> WPS UD4012* WPB UD7063 UD4098 18 AN3058* UD6012 UD7053 UD5086 UD5080 UD6034 UD7072 UD5095 UD5039* UD7062 UD7047 UD6022 UD4095 'WPB UD6102 19 AN3019* UD6078 WPB UD4077 WPS UD6080 AN3010 UD5103 WPB UO4005* UD5010* UD4101 UD6016 UD4039* AH3056*

20 AN3086* UD5085 UD 6015 l$ 7031 AH3057* UD6100 UD5094 UO4072 UD4033* WPB UO4041* UD5004>> UD7001 WPB UD5016*

21 AH3073* UD4042* WPB UD4076 WPB LYV156 WPB AH3128* 'WPS UD4038* WPB UD4015* UD7010 UD4027* UD4040*

22 AH3123* UD6079 UD4071 WPB UD7065 AN3050* UD7046 UD6021 UD4131 'WPB UD4026* WPS UD5014* WPB UD5003 23 AN3011* UD6077 UD6110 WPS UD5078 UD5102 UD5011* UD6029 AH3131* UD4087 UD5084 . UD5079 UD4116* UD5018*

24 XH2056* AH3037* UD6072 UD6001 un4138* UD5017* UD7060 'WPB UD5009* AN3055* UD7083 WPS UD4092 25 AN3009 AN3013* AH3102* AN3012>> UD6017 UD5020* AN3088* UD5076 UD6105 UD6071 UD6035 I$ 5008* UD4028*

26 AH3044* UD4145 UD6067 WPS UD7080 WPS AN30S7* WPS UD5082 WPS UD7004 27 AH3101* AN3018* UD6111 WPB UD4011* UD7054 UD4137* WA6001 UD4006* UD5077 28 AN3118 XH2081* UD6073 UD4094 WPS UD6055 WPS UD7013 WPB Xk2073*

29 AN3113 UD6014 UD4078 UD5081 UD6070 UD6076 UD5120 UD6018 30 AH3127" AH3071* AH3132* AH3072* AH3114* AH3Q'l4>> XH2065*

1 2 4 5 6 8 9 10 11 12 13 14 15 16 '17 18 19 20 '1 22 23 24 25 26 27 28 29 30 1 XH2095* AN3008* AN3095* AH3098* AH3021* AN3107* AN3025*

2 UD6066 UD5083 UD6050 UD6063 UD5052 UD4058 UD6065 AH3096>>

3 XH2108* WPS UD7027 WPB UD6019 WPS UD4059 UD6119 XH2099>> AN3126*

4 UD5068 UD4055 WA6004 UD4127 UD7067 UD4105 WPS UO6096 AH3028* AH3045*

5 UD7103 WPS UD5115 WPS AN3090* WPS UD7082 WPS UO6046 UO4147 AH3029*

6 UD4093 UD5044 UD6049 UD6047 UD6010 UD5073 AN3089* UD5043 UD6101 Ak3083* AN3134* AN3119* AN3130*

7 UD4065. WPS UD7077 AN3125* UD5109 WPS UD7043 UD5050 ,UD4109 UD6099 UD6040 AH3124* XN2094*

8 UD5116 UD4126 UD5108 UD5049 UD4073 AN3027* UD6064 UD5091 UD5046 UD5048 WPS UD6097 UD6109 Ak3022*

9 UD5015 WPB UD5045 WPS UD4124 WPS UD 4130 UO6044 UD7025 AN3085>> UD7018 WPB UD4096 UD6043 AN3030*

10 UD4119 UD4129 UO7091 UD4010 WPS UD4020 WPB AN3084* WPS " LYV155 WPS UD4022* WPB UD4110 AN3097>>

11 UD5041 WPB UD7105 UD5117 UD4001 WPS UD4123 uo4031* Uo5118 UD6011 AN3103* UD7040 UD6048 UD5047 AH3049*

12 AH3007>> UD4120 UD6042 UD4064 UD5051 UD4019 WPS UD5119 AH3081* UD6045 WPB UD4066 'WPB UD6025 AH3120*

13 UD6020 WPS UD4070 UD6107 UD7032 UD7099 UD5053 UD5067 UD7022 UD6104 UD5113 UD5133 UD7094 UD 6106 AN3082*

14 UD4063 UD7033 WPS UD4106 WPB UD4050 WPS UD4029* WPS UD5013* WPB UD4069 WPS UD 5110 AN3001*

15 UD5112 UD4057 UD6074 AN3026* UD5074 UD4009 UD5012 UD5035* UD4125 UD4056 UD7102 UD5114 XH1090 UD6098 XN2067*

16 UD5025* UD4084 UD6081 AN3060* UO5022* UD 4140* UD5027 UD5060 UD4003* UD4139", UD7066 UD5101 XH1141 UD6030 XH2100*

17 UO4080 UD7088 WPS UD4134* WPB UD 4142* WPS UD4081 'WPB UD5136 'WPB UD4067 WPS UD5026>> AH3122*

18 UD61'16 WPB UD4068 UD6027 UD7100 UD7056 uo5031* UD5021* UD7016 UD6006 UD5105 UD5092 UD7057 UD6008 AN3112*

19 AN3078* UD4007* UD6009 UD4079 UD5024* UO4014* WPB UD5090 AN3023* UD6093 WPB UD4086 'MPS UD6088- AH3063*

20 UD5037>> WPS UD7084 UD5106 UD4036>> WPB UD4023* UD4075 UD5033>> UD6118 AN3111* UD7106 UD6085 UD5023* AN3091*

21 UO4035* uo4008* UD7097 UD4013* WPB. uo4083* WPB AH3016>> WPB LYV154 WPB UD4060 WPS UD 4135* AH3116*

22 UD5006 WPB UD5100 WPB UD4037* WPB UD 4133 UD6032 UD7096 AN3093* UD7058 WPS UD4089 UD6092 AH3048*

23 UD5002 UD4004>> UD5107 UD5001 UD4090 AN3121* UD6023 UD5089 UD5088 UD5029* WPB UD6086 l$ 6089 AH3061*

24 UD4030* WPB UD7050 AH3077" UD5104 WPB UD7055 UD5099 UD4136* UD6003 UD6084 AN3129* XN2068*

25 UD4049 UD5096 UD6005 UD6024 UD6082 UD5097 AH3094* UO5098 UD6007 AH3059* AH3065* AH3005* AN3006*

26 UD7081 WPB UD5034" WPB AH3105* WPB UD7026 WPS UD6083 UD4148 AN3047" 27 un5038* UD4002 WA6002 UD4141* UD7052 UD 4132* 'WPB UD6051 AN3117 AN3108*

28 XN2060* WPB UD7035 WPB UD6090 WPS UD4074 UD6095 - XH2078* AN3017*

29 UD6031 UD5059 UD6091 uo6033 UD5032>> UD4085 UD6004 AN3109*

'0 XH2052* AN3015* AH3106*. AN3110>> AH3024* AN3115* AN3062*

16 17 18 19 20 21 -22 23 24 25 26 27 28 30 WPS are fresh 9x9-9X assemblies loaded in Cycle 9

>> Assemblies with Reused Channels

UNITED STATES NUCLEAR REGULATORY COMMISSION OFFICE OF NUCLEAR REACTOR REGULATION WASHINGTON, D.C. 20555 November 10, 1992 NRC INFORMATION NOTICE 92-74: POWER OSCILLAT 8NS AT WASHINGTON NUCLEAR POWER

~ 'NIT,.2 Addressees All holders of operating licenses or construction permits for boiling-water reactors (BWRs).

~Pur ose The U.S. Nuclear Regulatory Commission (NRC) is issuing this information notice to alert addressees to a recent event involving power oscillations in an operating region where instability had not been specifically predicted. It is expected that recipients'will review the information for applicability to their facilities and consider actions, as appropriate, to avoid similar problems. However, suggestions contained in this information notice are not NRC requirements; therefore, no specific action or written response is required.

~Back round On March 9, 1988, a thermal hydraulic instability event occurred at LaSalle Unit 2. The NRC discussed this event in Information Notice 88-39, "LaSalle Unit 2 Loss of Recirculation Pumps with Power Oscillation Event," and Bulletins 88-07 and 88-07, Supplement 1, "Power Oscillations in Boiling Water Reactors." In the first bulletin, the NRC requested licensees to establish procedures and give training to reactor operators to enable them to recognize oscillations and to take appropriate actions. In the supplement, the NRC requested licensees. to implement the General Electric (GE) Interim Recommendations for Stability Actions, designated the Interim Corrective Actions (ICA). GE defined the exclusion regions on the power/flow map in which, with varying probability, instability might be expected. Three regions were defined in which operation was to be avoided (immediate exit if entered) or limited (e.g., when required during startup). These regions were based on

'operating or test experience for reactors with GE fuel. The exclusion regions for new fuel designs were to be reevaluated and justified based on any applicable operating experience, calculated changes in core decay ratio using NRC-approved methodology, and/or core decay ratio measurements. Since .the LaSalle event in 1988, the NRC and the BWR Owners'roup (BWROG) have conducted extensive analyses and reviews of various aspects of stability while developing long-term solutions to augment or replace the ICA. On March 18, 1992, the BWROG sent a letter (BWROG-92030) to BWROG members 9211040206

IN 92-74 November 10, 1992 Page 2 of 5 transmitting "Implementation Guidance for Stability Interim Corrective Actions." In this letter, the BWROG emphasized the need for caution when operating near the exclusion regions. The BWROG also recommended reexamining procedures and training to reflect uncertainties in the definition of exclusion region boundaries.

'l ~

Descri tion of Circumstances ~

g On August 15, 1992, Washington Nuclear Power Unit 2 (WNP-2) experienced power oscillations during startup. The event occurred early in cycle 8 operation.

During, cycle, 8, the licensee had two previous startups without incident. The reactor core consisted primarily of Siemens fuel, with about 74 percent of this fuel in 8x8 fuel assemblies and about 25 percent in 9x9 fuel assemblies,

.and with the remainder of the core consisting of various lead test assemblies.

The 9x9 fuel assembly used in WNP-2, designated 9x9-9x, has a higher flow-resistance -than the 8x8 fuel assembly with a difference of about 10 percent in pressure drop.. These 9x9 fuel assemblies were loaded during cycles 7 and 8.

J About 33 hours3.819444e-4 days <br />0.00917 hours <br />5.456349e-5 weeks <br />1.25565e-5 months <br /> before the event, the licensee commenced a controlled power reduction from full power to 5-percent power to repair a valve packing leak in the drywell. After completing the repairs, the licensee began'a return to full power: The licensee increased reactor power to about 34 percent and then held it at that level for 3 hours3.472222e-5 days <br />8.333333e-4 hours <br />4.960317e-6 weeks <br />1.1415e-6 months <br /> to perform turbine bypass valve tests and control rod drive system timing tests. The recirculation syst'm was operated with flow control valves (FCVs) full open and pumps at slow speed.

After completing the tests, the operators continued the restart up the (approximately) 30-percent flow line to about 36-percent power (Figure 1).

This is at a power above the recirculation pump cavitation region. The operators then began closing one of the two FCVs in preparation for shifting the associated recirculation pump to fast speed. During this change, in which power and flow decreased along the 76-percent rod. line to a power/flow of about 34/27 percent, the operators observed power oscillations first on the average power range monitors (APRHs) and then by local power range monitors (LPRHs) downscale indications. Upon recognizing the power oscillations, the plant operators manually initiated a reactor scram. Post-event review indicated that the 2-second-period oscillations were in-phase (core-wide) and had grown to a peak-to-peak ampl'itude of about 25 percent of rated power.

Host of the oscillation amplitude'iricrease occurred in an interval of about 1 minute with the oscillations continuing at the limiting (maximum) amplitude for an additional minute before scram. The,oscillations occurred while the reactor was operating at a power about 4'percent of rated power below the lower. exclusion region boundary line (the nominal 80-percent rod line).

During later review, the licensee found no indication that fuel had failed because of the event.

IN 92-74 November 10, 1992 Page 3-'of 5 The NRC sent an Augmented Inspection Team (AIT) to the site to determine the possible causes and relevant facts of this event. The AIT concluded that the primary cause of the oscillations was very skewed radial and bottom peaked axial power distributions in the reactor (1.92 radial peaking factor and 1.62 core average axial peaking factor). These power distributions resulted from (1) the control rod pattern that the shift technical advisor selected for increasing the power and shifting the recirculation pump, speed, and (2) the relationship of this control rod pattern to the specific WNP-2 cycle 8 core fuel loading configuration. These rod patterns were primarily directed towards achieving the target full power configuration and did not consider stability concerns.

The AIT also found, by analyses using the LAPUR code, that a contributor to the oscillations was the core loading, consisting of a mixed core with unbalanced flow characteristics between the new 9x9-9x fuel and the old 8x8 fuel: The analyses indicated that a full core of the 9x9-9x fuel would be significantly less stable than the old 8x8 fuel, and that the mixed .core was.

less stable'than a fully loaded core of either fuel type. The analyses also indicated that while the oscillations would be in-phase (core-wide), as observed in the event, the out-of-phase (regional) instability boundary would be very close to the in-phase boundary (Figure 1). The AIT found that small changes in operating conditions could have resulted in out-of-phase oscillations, which would have been more difficult for the APRH system to detect.

WNP-2 has a Siemens Advanced Neutron Noise Analysis (ANNA) monitor, a stability monitor required by technical specifications only if the licensee intends to enter the lower exclusion region. Since the licensee did not intend to enter the exclusion region during this startup, the ANNA monitor was not put into the observation mode, although it was gathering data which was used later to confirm stability calculations performed after the event.

The licensee successfully restarted the unit after implementing the following restrictions for maintaining the limits on rod withdrawal patterns and power distribution in the low flow regions of concern.

The licensee analyzed the control rod patterns for stability before startup, and the operator could not.change these patterns without analysis and review.

0 The calculated maximum total peaking factor.was less than 3.4.

IN 92-74 November 10, 1992 Page 4 of 5 The calculated core average axial peaking factor was less than 1.45.

~ The Hinimum Critical Power Ratio was greater than 2.2.

The licensee analyzed the conditions at FCV closure and found a decay ratio of less than 0.5. The recirculation pump was shifted to fast speed with the reactor power less than 33 percent and the feedwater temperature greater than 146. I 'C -(295 'F).

The licensee continuously used the ANNA monitor when the reactor was operating above 25 percent power and below 50 percent flow.

Further detailed description of the event can be found in the AIT Inspection Report No. 50-397/92-30.

Discussion The WNP-2 power oscillation event indicates that the boundaries of the ICA regions, or modifications approved for various reactor technical specifications, do not necessarily encompass all stability limits Instability may occur beyond these boundaries if the reactor is operated with configurations outside those used to define the boundaries. This event presented direct evidence that the following factors can be significant contributors to the possibility of unstable operation.

Power distributions involving extremely skewed radial and axial peaking factors can induce unstable operation even in regions or with operating conditions not otherwise considered susceptible to oscillations.

Core loading patterns involving a mixture of fuel types with differing flow resistances can contribute to instability. 0 Reactors with two-speed recirculation pumps and FCVs can hinder stability because of the narrow range of operation between pump cavitation regions and possible instability regions.

The event also indicates the value of operating a stability monitor . The ANNA monitor could have given the operators information that instability was iqminent, prompting them to alter operations to avoid the oscillations.

IN 92-74

'November 10, 1992 Page 5,of 5 This information notice requires no specific action or written response. If you have any questions about the information in this notice, please contact one of the technical contacts listed below or the appropriate Office of Nuclear Reactor Regulation (NRR) project manager.

II ~

Brian K. Grimes, Director Division of Operating. Reactors Support Office of Nuclear Reactor Regulation Technical contacts: Howard Richings, NRR (301) 504-2888 Peter C. Wen, NRR (301) 504-2832 Attachments:

1. Figure 1. Best-Estimate Lines of Constant Decay Ratio=l.0 for Actual Conditions of WNP-2 8/15/1992 Event, Assuming Constant Power Distribution
2. List of Recently Issued NRC Information Notices

Attachment 1 IN 92-74 November 10, 1992 Page 1 of 1 WNP-2 8/15 STARTUP CONDITIONS LAPUR-est i ma% ed line of consta nt out- of-pha se DR=

70 60 100$ rod line 50

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sos rod line 45 40  :----t APU¹ est-i. maCeci-- I-'I-ne--of-constant in phase DR=1 6% rod one 25 20 20 25 30 35 40 45 55 60 Core Flow ( $ of Rated )

Figure L,, Best-estimate lines of constant decay ratio 1.0 for actual conditions of 8/15 event, assuming constant power distribution

Attachment 2 IN 92-74 November 10, 1992 Page 1 of 1 LIST OF RECENTLY ISSUED NRC INFORMATION NOTICES n ormatlon ate o Notice No. Subject Issuance Issued to 92-61, Loss of High Head 11/06/92 All holders of OLs or CPs Supp. 1 Safety Injection for nuclear power reactors.

92-73 Removal of A Fuel 11-04/92 All holders of OLs or CPs Element from A Re- for nuclear power reactors.

search Reactor Core While Critical 92-59, Horizontally-Installed 11/04/92 -

All holders of OLs or CPs Rev. 1 Motor-Operated Gate for nuclear power reactors.

Valves 92-72 Employee Training and 10/28/92 All U.S. Nuclear Regulatory Shipper Registration Commission Licensees.

Requirements for Trans-porting Radioactive Materials 91-64, Site Area Emergency 10/07/92 All holders of OLs or CPs Supp. 1 Resulting from A Loss for nuclear power reactors.

of Non-Class lE Uninterruptible Power Supplies 92-71 Partial Plugging of 09/30/92 All holders of OLs or CPs Suppression Pool for nuclear. power reactors:

Strainers At A Foreign BWR 92-70 Westinghouse Motor-Operated 09/25/92 All holders of OLs or CPs Valve Performance Data for nuclear power reactors.

Supplied to Nuclear Power Plant Licensees 92-69 Water Leakage from Yard 09/22/92 All holders of OLs or CPs Area Through Conduits for nuclear power reactors.

Into Buildings 91-'29, Deficiencies Identified 09/14/92 All holders of OLs or CPs Supp. 1 During Electrical Dis- for nuclear power reactors.

tribution System Func-tional Inspections perat>ng 1cense CP = Construction Permit

UNITED STATES FIRST CLASS MAIL NUCLEAR REGULATORY COMMISSION POSTAGE AND FEES PAID WASHINGTON, D.C. 20555-0001 USNRC PERMIT NO. G-67 OFFICIAL BUSINESS PENALTY FOR PRIVATE USE, $ 300

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,WASJQfJGQON.. , . OC 30555 PRINTED ON RECYCLEO PAPER

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