UTILIZATION OF MICROBURN-B2 FOR FUEL SHUFFLING OPERATIONAL AID Advances in Nuclear Fuel Management III Hilton Head Island, SC, USA October 5-8, 2003 D. Ziabletsev, H. Moon, R. G. Grummer Framatome ANP, Richland, WA, USA

> Presentation Title - Date - References 2 Introduction BWR Neutronics Core Design involves: Establishing previous cycle J-1 history Designing core loading pattern for current cycle J Developing control rod (CR) patterns Assessing other core operability aspects Verify cold shut down margin (CSDM) for Cycle J  CSDM (  k/k) – subcriticality of the core at 20C (68F) in with one CR “stuck” full out and all other rods full in

> Presentation Title - Date - References 3 Fuel Shuffling  Fuel shuffling from Cycle J-1 loading pattern to Cycle J loading pattern goes through intermediate refueling loading patterns.  Refueling loading pattern CSDM calculation involves analysis of several hundred loading patterns.  MICROBURN-B2 has the capability of fast shut down margin evaluations with the accuracy of 1mk (.001  k)  In this paper:  MICROBURN-B2 modified to automatically evaluate up to 1000 refueling loading patterns developed by a utility planner  Most of the loading patterns include water holes (empty bundle regions). The validity of MICROBURN-B2 CSDM calculations involving water holes is evaluated.

> Presentation Title - Date - References 4 Interface to Fuel Shuffling Management Tool A BWR plant operator generates several hundred sequential refueling loading patterns with its own fuel shuffle management tool MICROBURN-B2 can read and process as many as 1000 loading patterns in a given format MICROBURN-B2 performs shuffling and calculates CSDM for each loading pattern sequentially and provides summary at the end of run. MICROBURN-B2 can be easily adopted to read loading patterns in any data format

> Presentation Title - Date - References 5 Interface to Fuel Shuffling Management Tool  Example of an intermediate core loading pattern generated in a specific format by a BWR plant operator ID(09,01)= "WAC109WQD002" ID(08,02)= "WQD006WQF137WQF130" ID(06,03)= "WAC107WQD008WQF138WQD038WQG140" ID(06,04)= "WQD060WQF129WQG121WQG182WQF144" ID(05,05)= "WAC134WQF235WQF234WQG266WQF131WQG118" ID(03,06)= "WAC133WQD065WQF240WQG147DUM002WQE011DUM003WQE109" ID(03,07)= "WQD030WQF163WQF233WQG146WQF224DUM005WQE111WQG142" ID(02,08)= "WQD029WQF141WQG138WQG174WQE036WQG185WQF227WQG141WQF231" ID(01,09)="WAC131DUM007WQD004WQG183WQF154DUM008WQE010WQG131WQD058WQF252" ID(01,10)="WQD031WQF149WQG120WQF158WQG134WQE038WQG130WQF239WQF248WQE017" ID(01,11)="WAC142WQF166WQF160WQG175WQF145WQG136WQF165WQG192WQF164WQG117" ID(01,12)="WQD028WQF229WQG188WQE035UDH217WQE022WQG186WQE108WQG116WQE027" ID(01,13)="WQD032WQF156WQF152WQG265WQF236WQF244WQF238WQG115WQF161WQG137" ID(01,14)="WAC135WQF127WQG139WQE037WQG135WQE031WQG132WQE047WQG176WQE048" ID(01,15)="WQE033WQF225WQD067WQG177WQF153WQG240WQF159WQG264WQF157WQG187" ID(01,16)="WQE067WQF221WQD069WQG211WQF102WQG244WQF097WQG222WQF095WQG238"

> Presentation Title - Date - References 6 Modeling of Water Holes Water holes are represented as dummy assemblies on a loading map, e.g. names such as “DUM001” or “DUM014” In MICROBURN-B2 water holes are modeled with a natural U lattice or a fictitious lattice mimicking water hole (WHL) To justify the employment of water hole model in MICROBURN-B2, CASMO-4 colorset calculations are performed.

> Presentation Title - Date - References 7 Modeling of Water Holes 30 GWd/T WHL 20 GWd/T 10 GWd/T  Jx1  Jx2  Jx1 Jy1 Jy2 Jy1 Jy2 n WHL – Water Hole Lattice Vary metal to water ratio

> Presentation Title - Date - References 8 Modeling of Water Holes Effect of Water Hole Quadrant on the Colorset Keff

> Presentation Title - Date - References 9 Core Shuffling and CSDM Calculations with MICROBURN- B2 n RLP 1 n RLP2 n ….. n RLP N n RLP1: CSDM for All Rods n RLP l: CSDM for selected rods n Summary for all RLPs

> Presentation Title - Date - References 10 Core Shuffling and CSDM Calculations with MICROBURN- B2 For the first loading pattern MICROBURN-B2 performs core shuffling and calculates CSDM for all control rods (N rods). Calculation of CSDM for one rod includes calculation of 10-by-10 assembly square surrounding the rod. All N CSDM values for the first loading pattern are saved. For the second loading pattern core is shuffled and assembly names in 10-by-10 square surrounding each rod are compared with those from the first loading pattern. Rod calculation is skipped and CSDM value is taken from the previous run if names in 10-by-10 square aren’t changed. After all N CRs are processed, CSDM values are saved again. The same algorithm is repeated again for all subsequent loading patterns given in the input file.

> Presentation Title - Date - References 11 Core Shuffling and CSDM Calculations with MICROBURN- B2  MICROBURN-B2 output contains 2-D maps with Keff and correspondent CSDM for each loading pattern and final short summary with maximum rod Keff (minimum CSDM) for each pattern.  Three sets of calculations are performed: Set of 174 trial loading patterns with WHL(depleted U) mimicking water holes. One MB2 run for all 174 patterns. Set of 174 trial loading patterns with natural U mimicking water holes. One MB2 run for all 174 patterns. Conventional full core MICROBURN-B2 verification calculations for some 22 out of 174 selected loading patterns and natural U mimicking water holes. 22 separate MB2 runs per each loading pattern.

> Presentation Title - Date - References 12 Core Shuffling and CSDM Calculations with MICROBURN- B2

> Presentation Title - Date - References 13 Core Shuffling and CSDM Calculations with MICROBURN- B2

> Presentation Title - Date - References 14 Core Shuffling and CSDM Calculations with MICROBURN- B2

> Presentation Title - Date - References 15 MICROBURN-B2 Efficiency HP-C180 Platform (180 MHz PA-9000) 5.2 hr for 174 loading patterns in one set or ~108 sec per one pattern HP-C3600 Platform (552 MHz PA-8600) 3 times calculation speed up or ~ 35 sec per one pattern

> Presentation Title - Date - References 16 Conclusion MICROBURN-B2 is capable to automatically perform series of trial loading pattern evaluations in a format given by a BWR plan operator performing fuel shuffling and calculating cold shut down margin MICROBURN-B2 preserves the conservatism of CSDM calculations utilizing water hole model with natural U MICROBURN-B2 is accurate and efficient tool for BWR core shuffling management