ML17292A640

Forwards Rept Qualification of Supply Sys Use of RODEX2 Code, for Gap Conductance Calculation in Topical Rept WPPSS-FTS-131, Applications Topical Rept for BWR Design & Analysis. Rept Provides Justification for Use of Code

ML17292A640
Person / Time
Site:	Columbia
Issue date:	12/27/1996
From:	BEMIS P R WASHINGTON PUBLIC POWER SUPPLY SYSTEM
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
GO2-96-252, NUDOCS 9701060119
Download: ML17292A640 (19)

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CATEGORY j.Pj.REGULATOO INFORMATION DISTRIBUTION+STEM (RIDE)~ACCESSIOA NBR:9701060119 DOC.DATE!96/12/27 NOTARIZED:

NO DOCKET g FACI1::50-397 WPPSS Nuclear Project, Unit 2, Washington Public Powe 05000397 AUTH.NAME AUTHOR AFFILIATION BEMIS,P.R.

Washington Public Power Supply System RECIP.NAME RECIPIENT AFFILIATION Document Control Branch (Document Control Desk)

SUBJECT:

Forwards rept"Qualification of Supply Sys Use of RODEX2 Code," for Gap qonductance cal,culation in topical rept WPPSS-FTS-131,"Applications Topical Rept for BWR Design&Analysis.Rept provides justification for use of code.DISTRIBUTION CODE: A001D COPIES RECEIVED: LTR I ENCL 5 SIZE:/TITLE: OR Submittal:

General Distribution NOTES: RECIPIENT ID CODE/NAME PD4-2 LA COLBURN,T INTERNAL: ACRS NRR/DE/ECGB/A NRR/DRCH/HICB NRR/DSSA/SRXB OGC/HDS3 EXTERNAL: NOAC COPIES LTTR ENCL 1 1 1 1 1 1 1 1 RECIPIENT ID CODE/NAME PD4-2'PD E CENTER 01 NRR NRR/DSSA/SPLB NUDOCS-ABSTRACT NRC PDR COPIES LTTR ENCL NOTE TO ALL"RIDS" RECIPIENTS:

PLEASE HELP US TO REDUCE WASTE!CONTACT THE DOCUMENT CONTROL DESK, ROOM OWFN SD-5(EXT.415-2083)TO ELIMINATE YOUR NAME FROM DISTRIBUTION LISTS FOR DOCUMENTS YOU DON'T NEED!TOTAL NUMBER OF COPIES REQUIRED: LTTR 14 ENCL ,9 P<<p WASHINGTON PUBLIC POWER SUPPLY SYSTEM P.O.Box 968~Richland, Washington 99352-0968 December 27, 1996 G02-96-252 Docket No.50-397 U.S.Nuclear Regulatory Commission Attn: Document Control'Desk Washington, D.C.20555*Gentlemen:

Subject:

WNP-2, OPERATING LICENSE NPF-21 QUALIFICATION OF SUPPLY SYSTEM USE OF RODEX2 CODE FOR THE GAP CONDUCTANCE CALCULATION IN TOPICAL REPORT WPPSS-FTS-131,"APPLICATIONS TOPICAL REPORT FOR BWR DESIGN AND ANALYSIS"

References:

1)Letter GO2-93-021, dated January 27, 1993, from G.C.Sorensen to NRC,"Nuclear Plant No.2, Operating License NPF-21, Notification of Request for NRC Review of Topical Report WPPSS-FTS-131, Rev.1,'Applications Topical Report for BWR Design and Analysis'" 2)Letter dated June 4, 1996, TG Colburn (NRC)to JV Parrish (SS),"Issuance of Amendment for the Washington Public Power Supply System Nuclear Project No.2 (TAC No.M95247)" In response to discussions with the staff, the attached report provides justification for Supply System use of the NRC approved RODEX2 computer code.This code was developed by Siemens Power Corporation (SPC)for calculation of gap conductances in reactor fuel for applications to BWR transient analysis as described in Revision 1 of the"Applications Topical Report for BWR Design and Analysis, WPPSS-FTS-131A" issued to section 6.9.3.2 of the WNP-2 Technical Specifications by Reference 2.No specific action by the staff is requested by this letter.970i060119 96i227 PDR ADQCK 05000397 P PDR Page 2 QUALIFICATION OF SUPPLY SYSTEM USE OF RODEX2 Should you have any questions or desire additional information regarding this matter, please call me or Ms.L.C.Fernandez at (509)377-4147.Respectfully, P.R.Bemis Vice President, Nuclear Operations Mail Drop PE23 Attachment CC: JE Dyer-NRC RIV KE Perkins, Jr.,-NRC RIV, Walnut Creek Field Office TG Colburn-NRR NS Reynolds-Winston&Strawn DL Williams-BPA/399 RC Barr-NRC, WNP-2/297N

~0 , QUALIFICATION OF SUPPLY SYSTEM USE OF RODEX2 CODE Attachment Page 1 of 11 P~ur 0 e The purpose of this report is to document the Supply System's qualification to use SPC's RODEX2'ode to calculate gap conductances.

This qualification will satisfy the requirement of using RODEX2 for gap conductance calculations in the Supply System reload methodology documented in the report WPPSS-FTS-131A~, as issued by the NRC to section 6.9.3.2 of the WNP-2 Technical Specification.

VeriTic tion nd Validati n n Tn tallation of R DEX2 a u I stem The RODEX2 code developed by SPC and approved by the NRC'as been installed on the Supply System IBM workstation RISC6000.The Supply System performed installation verification and validation of the code according to the Supply System Engineering Directorate Manual EDP 2.16"Production Computer Program and Data Base Control," which conforms to FSAR Chapter 17 Quality Assurance requirements.

Three sample problems provided by SPC4 for the purpose of validating the code installation were run on the Supply System computer.These sample problems, designated as Cases 1, 2, and 3, had 160, 166, and 365 time steps respectively.

The Supply System results were identical to the SPC results for all analytical steps.Attached Tables 1, 2, and 3 provide a comparison of the Supply System and SPC results for the final time step.Only the final step is shown in the tables because the effect of any differences between the analytical results at intermediate time steps would proliferate, thereby affecting the results for the final time step.It should be noted that the first three rows in Tables 1, 2, and 3 are computer input, and the remaining rows are from the computer output.As can be seen, the Supply System outputs are identical to the SPC outputs.This demonstrates that the RODEX2 code as installed on the Supply System IBM workstation RISC6000 provides identical results as the same code installed on SPC computers.

Methodolo for eneratin ore Avera e and Hot Channel G onductanc The methodology used for the calculation of core average and hot channel gap conductances is the same as that of SPC except the codes used for burnup histories as explained below.The Supply System uses SIMULATE-E, which is part of the physics codes as approved by the NRC for WNP-2 reload analysis'o compute burnup histories for each batch and for the hot bundles.SPC uses MICROBURN-B.

The main input to RODEX2 includes mechanical design parameters, such as pellet and clad materials and dimensions, and burnup histories, which include LHGR histories, axial power profiles, coolant enthalpy, coolant flow rates and reactor pressure.The axial and radial fuel rod powers used as input to the RODEX2 code are determined from core follow and predicted control rod step-through SIMULATE-E calculations.

These SIMULATE-E calculations are used as input to determine both the core average gap conductance and hot channel gap conductance for each fuel design.'

,QUALIFICATION OF SUPPLY SYSTEM USE OF RODEX2 CODE Attachment Page 2 of 11 The core average gap conductance is determined by RODEX2 using as input the SIMULATE-E core follow and predicted control rod step-through calculations as follows.First, the average gap conductance is determined for each batch in the core for the initial conditions of the transient.

This is done by using SIMULATE-E to calculate the batch average axial power history, the batch average radial power history and the batch average flow history from the time when the batch was first inserted into WNP-2 until the exposure where the transient is initiated.

These average batch histories are input to RODEX2 to calculate an average gap conductance for each batch.Following SPC's methodology, the core average gap conductance is then determined from the batch average gap conductances by power and assembly weighing each batch according to the following formulation: (BAGS xNq xBARPq)CAGC-(NgxBARPg)where CAGC=Core Average Gap Conductance, BAGC=Batch Average Gap Conductance, N=Number of Assemblies and BARP=Batch Average Radial Power.The hot channel gap conductance for each fuel design (8x8, 9x9-9X, etc.)is determined by RODEX2 using as input the SIMULATE-E core follow and predicted control rod step-through calculations as follows.For each fuel design at the point of initial conditions for the transient, the assembly with the minimum critical power ratio is selected as the hot channel.Then for each selected assembly, the axial power history, radial power history and flow history are calculated using SIMULATE-E from the time it is first inserted into the WNP-2 core until the exposure where the transient is initiated.

These histories are input to RODEX2 to calculate the hot channel gap conductance for each fuel design.Once the RODEX2 calculation has determined the historical effects on the gap conductance, the gap conductance in the hot channel is determined at varying power conditions.

The resulting gap conductances are used in subsequent analysis as described in the Applications Topical Report WPPSS-FTS-131A2.

This approach is consistent with SPC's application of RODEX2.u I stem Res I nd om arison with SPC Tables 4 through 7 provide gap conductance calculations and comparisons with SPC results for Cycles 8, 10 and 11.Table 4 gives the core average results.Tables 5 through 7 give the hot channel results.The data in Table 5 through 7 are also plotted as Figures 1 through 6.The gap conductances for Cycle 9 are not compared because the Supply System did not perform the Cycle 9 calculation.

The differences in calculated gap conductances are attributed mainly to differences in burnup histories introduced by the different depletion codes (SIMULATE-E versus MICROBURN-B) and differences in the core follow and rodded depletions used in these codes.It should be noted that in the gap conductance calculations, the burnup histories for earlier cycles i, 1'-)fP,

, QUALIFICATION OF SUPPLY SYSTEM USE OF RODEX2 CODE Attachment Page 3 of 11 (Cycle 7 and earlier for the Cycle 8 analysis, Cycle 6 and earlier for the Cycle 10 and 11 analyses)were based on Haling depletion.

The larger differences seen in the 8x8 hot channel gap conductance for Cycle 8 are primarily attributed to the use of a Haling depletion in SIMULATE-E for Cycle 7.These Haling depletions were part of the Supply System approach for determining gap conductances prior to adopting the SPC methodology.

However, rodded step-throughs were used for later cycles to be consistent with SPC methodology.

The hot channel gap conductance comparisons are based on analyzing the assemblies that were selected by SPC using MICROBURN-B.

The results show excellent agreement.

The differences in gap conductance are summarized below (note: the positive values are non-conservative for core-wide and conservative for hot channel.The impact of the differences for core-wide is much less than the impact for hot channel.)Percent Difference in a Conductance cycle~ore-Wide CI gX9 8 10 11 4.9%0.2%1.7%-3,5%-1.9%1.4%2.9%0%0.5%*Typically, the LHGR for 8X8 hot channel for the b, CPR calculation is-11 kW/ft, and for 9X9 it is-7 kW/ft.The differences listed in the above table are based on these LHGRs, In summary, the Supply System calculated gap conductances for both core average and hot channel compare very closely with SPC's results.The small differences are mainly caused by the different depletion codes used by the Supply System and SPC to generate inputs to RODEX2.It is further concluded that the impact of the differences in gap conductance on thermal limits are within the overall accuracy of the calculations,

.QUALIFICATION OF SUPPLY SYSTEM USE OF RODEX2 CODE Attachment Page 4 of 11 TABLE 1 CASE 1 OUTPUT-SUPPLY SYSTEM VERSUS SIEMENS POWER CORPORATION Time Step No.Time (hours)LHGR (kw/ft)Fill Pres.(psia)Therm.Gap (mil)Gap Coef.(Btu/hr/ft'/F)

Tclad (F)T-Max (F)T-Avg (F)T-Sur (F)Release Frac (%)Burnup (GWD/MTU)Contact Pressure (psi)Supply System*160 17915.2 11.7 1491.0.135 7429.777.352 2663.7 1644.9 845.0 5.51 49.687 6142.7 Siemens Power Corp.*160 17915.2 11.7 1491.0.135 7429.777.352 2663.7 1644.9 845.0 5.51 49.687 6142.7*Results are for axial node 7 of a 13-node rod.

~QUALIFICATION OF SUPPLY SYSTEM USE OF RODEX2 CODE Attachment Page 5 of 11 TABLE 2 CASE 2 OUTPUT-SUPPLY SYSTEM VERSUS SIEMENS POWER CORPORATION Time Step No.Time (hours)LHGR (kw/ft)Fill Pres.(psia)Therm.Gap (mil)Gap Coef.(Btu/hr/ft~/F)

Tclad (F)T-Max (F)T-Avg (F)T-Sur (F)Release Frac (%)Burnup (GWD/MTU)Contact Pressure (psi)Supply System*166 11664.0 15,5 254.0.373 3392.717.414 3330.5 1962.0 879.8 1.74 21.317 126.5 Siemens Power Corp.*166 11664.0 15.5 254.0.373 3392.717.414 3330.5 1962.0 879.8 1.74 21.317 126.5*Results are for axial node 10 of a 24-node rod.

.QUALIFICATION OF SUPPLY SYSTEM USE OF RODEX2 CODE Attachment Page 6 of 11 TABLE 3 CASE 3 OUTPUT-SUPPLY SYSTEM VERSUS SIEMENS POWER CORPORATION Time Step No.Time (hours)LHGR (kw/ft)Fill Pres.(psia)Therm.Gap (mil)Gap Coef.(Btu/hr/ft'/F)

Tclad (F)T-Max (F)T-Avg (F)T-Sur (F)Release Frac (%)Burnup (GWD/MTU)Contact Pressure (psi)Supply System*365 26719.0 17.6 217.0.386 1758.730.515 3997.2 2355.4 1004.3 5.95 23.699 181.9 Siemens Power Corp.*365 26719.0 17.6 217.0.386 1758.730.515 3997.2 2355.4 1004.3 5.95 23.699 181.9*Results are for axial node 13 of a 24-node rod.

.QUALIFICATION OF SUPPLY SYSTEM USE OF RODEX2 CODE Attachment Page 7 of 11 TABLE 4 COMPARISON OF CORE-WIDE GAP CONDUCTANCES Core-Wide Hg p at Rated Power (in Btu/hr/ft'/F):

Cycle Number 10 Hg~p Supply System 627.6*693.6+*774.5**Hggp Siemens Power Corp.598+692++761+++%Diff, 4.9 0.2 1.7 Supply System used rodded step-through depletion for Cycle 8, but used Haling depletion in earlier cycles (Supply System Calculation No.NE-02-94-13"Core Wide Gap Conductance for Cycle 8 Using RODEX2").Supply System used rodded step-through depletion for batches beginning in Cycle 7, but used Haling depletion in earlier cycles (Supply System Calculation No.NE-02-95-29,"Revised Gap Conductances for Cycles 10 and 11").+From Siemens Power Corporation Report EMF-92-039, Revision 1,"WNP-2 Cycle 8 Plant Transient Analysis," June 1992++From Siemens Power Corporation Report EMF-94-095,"WNP-2 Cycle 10 Plant Transient Analysis," June 1994+++From Siemens Power Corporation Report EMF-95-006,"WNP-2 Cycle 11 Plant Transient Analysis," March 1995 ts~A l

~QUALIFICATION OF PLY SYSTEM USE OF RODE ODE~Attachment Page 8 of 11 Table 5 COMPARISON OF HOT CHANNEL GAP CONDVCTANCES FOR CYCLE 8 Hot Channel Gap Conductance for 8x8 Fuel at EOCS LHGR (kW/ft)H~Supply System~H~Siemens Power Corp.~~%Diff.4 7 14 74 15 51 1752-4,-.5 From upp y ystem a cu ation No.NE--4-Hot anne ap on uctance Calculation for Cycle 8 Using RODEX2 Code".From SPC Letter SPCWP-94-016"RODEX2 Data", Feb.14, 1994.Hot Channel Gap Conductance for 9x9 Fuel at EOC8 LHGR (kw/ft)10 12 13 15 Supply System*397 429 463 500 542 589 70 780 8 7 972 1102 1265 1479 17 3 H~Siemens Power Corp.~~381 413 484 525 573 26 689 7 2 850 956 1087 1254 1474 1770%Diff.4.2 3.9 3.3 3.2 2.8 2.9 2.5 2.4 2.0 1.7 1.4 0.9 0.3 rom upp y ystem a cu ation o.---ot anne ap on uctance Calculation for Cycle 8 Using RODEX2 Code".From SPC Letter SPCWP-94-016"RODEX2 Data", Feb.14, 1994.

~QUALIFICATION OF PLY SYSTEM USE OF RODE ODE Attachment Page 9 of 11 TABLE 6 COMPARISON OF HOT CHANNEL GAP CONDUCTANCES FOR CYCLE 10 Hot Channel Gap Conductance for SxS Fuel at EOC10 LHGR (kW/ft)H~Supply System~H~Siemens Power Corp.~~%Diff.1 7 22 541 711 55 74 1474 1774 1 7 17 7-1.4 From upp y ystem cu ation No.E--5-Revis ap on uctance or Cycle 10 and 11" From SPC letter dated September 26, 1995,"RODEX2 Data", SPCWP:042:95 Hot Channel Gap Conductance for 9x9 Fuel at EOC10 LHGR (kW/ft)10 12 13 14 15 H~Supply System~382 415 450 487 530 578, 634 699 77 868 980 1119 1299 1537 18 1 H~Siemens Power Corp.~~381 414 487 529 578 634 699 776 8 8 980 1120 1301 1541 1868%Diff.0.2 0.24 0.24 0.19-0.09-0.15-0.26-0.37 rom upp y ystem a cu ation o.--ap on uctance tor yc e 10." From SPC letter dated September 26, 1995,"RODEX2 Data", SPCWP:042:95

~~

-QUALIFICATION OF PLY SYSTEM USE OF RODE ODE~Attachment Page 10 of 11 TABLE 7 COMPARISON OF HOT CHANNEL GAP CONDUCTANCES FOR CYCLE 11 Hot Channel Gap Conductance for 8x8 Fuel at EOC11 LHGR (kW/ft)H~Supply System~141 17 H~Siemens Power Corp.~~1 4 17.%Diff.1.7 1.4 1.7 17 1 4 77 1745 1 5 177 1.4 1.4 1.4 1.2 rom upp y ystem a cu ation No.NE--4-74 ap on uctances or yc e 11." From SPC letter dated September 26, 1995,"RODEX2 Data", SPCWP:042:95 Hot Channel Gap Conductance for 9x9 Fuel at EOC11 LHGR (kW/ft)10 12 13 14 15 H~Supply System*383 417 452 492 536 587 717 902 1028 1192 1410 1711 2154 H~p Siemens Power Corp.**384 418 453 492 536 586 712 793 891 1013 1170 1377 1660 2072%Diff.-0.26-0.24-0.22 0.17 0.47 0.70 0.88 1.2 1.5 1.9 2.4 3.1 4.0 rom upp y ystem a cu ation o.---ap on uctances or yc e 11." From SPC letter dated September 26, 1995,"RODEX2 Data," SPCWP:042:95

-QUAI IFICATION OF PLY SYSTEM USE OF RODEX2 ODE" Attachment Page 11 of 11 REFERENCES 1.K.R.Merckx et al.,"RODEX2 Fuel Rod Thermal-Mechanical Response Evaluation Model," XN-NF-81-58(P)(A), Revision 2 and Supplement 1 and 2, March 1984 2.3.4.5.Letter, G02-93-021, dated January 27,1993, from G.C.Sorensen to NRC,"Nuclear Plant No.2, Operating License NPF-21, Notification of Request for NRC Review of Topical Report WPPSS-FTS-131A, Rev.1,'Applications Topical Report for BWR Design and Analysis'" Letter from C.O.Thomas (NRC)to J.C.Chandler (SPC),"Acceptance for Reference of Licensing Topical Report XN-NF-81-58(P),'RODEX2 Fuel Rod Thermal Mechanical Response Evaluation Model', Revision 2", Nov.16, 1983 Letter SPCWP-93-0009 from Y.V.Fresk, Siemens, to R.A.Vopalensky, Supply System,"RDX2LSE Computer Code," dated January 25, 1993 Letter from James Clifford, NRC, to G.C.Sorensen, Supply System,"Evaluation of Topical Report WPPSS-FTS-127

'Qualification of Core Physics for BWR Design and Analysis'TAC No.M76783)," dated October 23, 1992 i s~;IW la