Hangbok Choi

Physics study on direct use of spent pressurized water reactor fuel in CANDU (DUPIC)

Physics studies have been performed for the compatibility of DUPIC fuel design to the existing CANDU-6. The DUPIC fuel is made of spent pressurized water reactor fuel through a dry process, and the bundle design utilizes an advanced CANDU fuel bundle geometry that is mechanically compatible with the current fuel channel and refueling system. The characteristics of a DUPIC core are compared to the current operation limits and performances of a natural uranium core. The refueling simulations have shown that the channel and bundle powers are well below the operation limits for the two- and four-bundle shift refueling schemes. The fuel performance parameters during the refueling operation reserve enough margin to the stress corrosion cracking threshold of natural uranium fuel. With the aid of burnable poison material in the fuel, the safety performance of a DUPIC core is made comparable to that of a natural uranium core. The details of DUPIC fuel design and analysis are described.

Economic Analysis on Direct Use of Spent Pressurized Water Reactor Fuel in CANDU Reactors—IV: DUPIC Fuel Cycle Cost

Abstract A preliminary conceptual design of a Direct Use of spent Pressurized water reactor (PWR) fuel In Canada deuterium uranium (CANDU) reactors (DUPIC) fuel fabrication plant was studied, which annually converts spent PWR fuel of 400 tonnes heavy element (HE) into CANDU fuel. The capital and operating costs were estimated from the viewpoint of conceptual design. Assuming that the annual discount rate is 5% during the construction (5 yr) and operation period (40 yr) and contingency is 25% of the capital cost, the levelized unit cost (LUC) of DUPIC fuel fabrication was estimated to be 616

Composition adjustment on direct use of spent pressurized water reactor fuel in CANDU

/kg HE, which is mostly governed by annual operation and maintenance costs that correspond to 63% of LUC. Among the operation and maintenance cost components being considered, the waste disposal cost has the dominant effect on LUC (~49%). From sensitivity analyses of production capacity, discount rate, and contingency, it was found that the production capacity of the plant is the major parameter that affects the LUC.

Compatibility analysis on existing reactivity devices in CANDU 6 reactors for DUPIC Fuel cycle

In the DUPIC fuel cycle, spent pressurized water reactor (PWR) fuel is refabricated as a DUPIC fuel by a dry process. Because the spent PWR fuel composition depends on the initial enrichment and burnup conditions of PWR fuel, the composition of DUPIC fuel is not uniquely defined. To reduce the effects of such a composition heterogeneity on core performance, an adjustment of DUPIC fuel composition was studied. The composition adjustment was made in two steps: mixing two spent PWR fuel assemblies of higher and lower 239 Pu contents and blending in fresh uranium with the mixed spent PWR fuels, Because the fuel and core performances depend on both the absolute amount of fissile isotopes and the ratio of major fissile isotope contents, a parametric study was performed to determine the reference compositions of 235 U and 2 39 Pu. The reference enrichments of 233 U and 239 Pu were determined such that the DUPIC core performance is comparable to that of a natural uranium core with high spent PWR fuel utilization and low fuel cycle cost. Under this condition, it is possible to utilize 90% of spent PWR fuels as the DUPIC fuel formula. On average, the amounts of slightly enriched and depleted uranium used for blending correspond to 8.6 and 10.6%, respectively, of the mass of candidate spent PWR fuels.

DYNAMIC MODELING AND ANALYSIS OF ALTERNATIVE FUEL CYCLE SCENARIOS IN KOREA

Abstract The performance of reactivity devices for a Canada deuterium uranium (CANDU) 6 reactor loaded with Direct Use of Spent Pressurized Water Reactor Fuel In CANDU reactors (DUPIC) fuel is assessed. The reactivity devices studied are the zone controller units, the adjuster rods, and the mechanical control absorbers. For the zone controller system, the bulk reactivity control, spatial power control, and damping capability for spatial oscillation are investigated. For the adjusters, the xenon override, restart after a poison-out, shim operation, and power step-back capabilities are confirmed. The mechanical control absorber is assessed for the function of compensating temperature reactivity feedback following a power reduction. This study shows that the current reactivity device system of a CANDU 6 reactor is compatible with DUPIC fuel for normal and transient operations.

A liquid-metal reactor for burning minor actinides of spent light water reactor fuel-I: Neutronics design study

The Korean nuclear fuel cycle was modeled by the dynamic analysis method, which was applied to the once-through and alternative fuel cycles. First, the once-through fuel cycle was analyzed based on the Korean nuclear power plant construction plan up to 2015 and a postulated nuclear demand growth rate of zero after 2015. Second, alternative fuel cycles including the direct use of spent pressurized water reactor fuel in Canada deuterium uranium reactors (DUPIC), a sodium-cooled fast reactor and an accelerator driven system were assessed and the results were compared with those of the once-through fuel cycle. The once-through fuel cycle calculation showed that the nuclear power demand would be 25 GWe and the amount of the spent fuel will be tons by 2100. The alternative fuel cycle analyses showed that the spent fuel inventory could be reduced by more than 30% and 90% through the DUPIC and fast reactor fuel cycles, respectively, when compared with the once-through fuel cycle. The results of this study indicate that both spent fuel and uranium resources can be effectively managed if alternative reactor systems are timely implemented along with the existing reactors.

A fast-running fuel management program for a CANDU reactor

A liquid-metal reactor was designed for the primary purpose of burning the minor actinide waste from commercial light water reactors (LWRs). The design was constrained to maintain acceptable safety performance as measured by the burnup reactivity swing, the Doppler constant, and the sodium void worth. Sensitivity studies were performed for homogeneous and decoupled core designs, and a minor actinide burner design was determined to maximize actinide consumption and satisfy safety constraints. One of the principal innovations was the use of two core regions, with a fissile plutonium outer core and an inner core consisting only of minor actinides. The physics studies performed here indicate that a 1200-MW(thermal) core is able to consume the annual minor actinide inventory of about 16 LWRs and still exhibit reasonable safety characteristics.

Benchmarking MCNP and WIMS/RFSP Against Measurement Data - I: Deuterium Critical Assembly

Abstract A fast-running fuel management program for a CANDU reactor has been developed. The basic principle of this program is to select refueling channels such that the reference reactor conditions are maintained by applying several constraints and criteria when selecting refueling channels. The constraints used in this program are the channel and bundle power and the fuel burnup. The final selection of the refueling channel is determined based on the priority of candidate channels, which enhances the reactor power distribution close to the time-average model. The refueling simulation was performed for a natural uranium CANDU reactor and the results were satisfactory.

Benchmarking MCNP and WIMS/RFSP Against Measurement Data - II: Wolsong Nuclear Power Plant 2

Abstract Benchmark calculations have been performed for the conventional Canadian deuterium uranium (CANDU) core analysis code RFSP and the Monte Carlo code MCNP-4B using experimental data from the deuterium critical assembly. The benchmark calculation was carried out for the effective multiplication factor (keff), void reactivity, local power peaking factor (LPPF), and power distribution of a uniform core with 1.2 wt% UO2 and two-region cores with PuO2-UO2 fuels. The RFSP calculation was performed with two energy groups, using lattice parameters generated by WIMS-AECL with the ENDF/B-V cross-section library. The RFSP calculation has shown that the root-mean-square (rms) errors of the keff and the void reactivity are within 0.6% δk and 0.3% δ(1/k), respectively. The MCNP simulation was performed using a fully heterogeneous core model that explicitly describes the individual fuel rod and channel. The simulation showed an excellent agreement for the keff against the measurement, while the rms error of the void reactivity was 0.4% δ(1/k). The LPPF and core power distribution estimated by both codes matched those of the measurements within 4 and 9%, respectively. Conclusively, the physics analysis by the RFSP code in conjunction with the WIMS-AECL produces credible results for the light water–cooled and heavy water–moderated system. In addition, the MCNP-4B code has proved its potential as a computational benchmarking tool for the heavy water–moderated system.

Economic analysis on direct use of spent pressurized water reactor fuel in CANDU reactors-III : Spent DUPIC fuel disposal cost

Abstract Benchmark calculations of the Canada deuterium uranium reactor design and analysis codes were performed for the Monte Carlo and conventional methods using Phase-B measurement data of the Wolsong Nuclear Power Plant 2. In this study, the benchmark calculations were done for the criticality, boron worth, reactivity device worth, and flux scan. For the benchmark calculation of the Monte Carlo method by MCNP-4B, the criticality was estimated within 4 mk. The reactivity worth of the control devices was consistent with the measurement data within 15%. For the benchmark calculation of the conventional method composed of WIMS-AECL, SHETAN, and RFSP, the criticality was also predicted within 4 mk. The reactivity device worth was generally consistent with the measured data except for the strong absorbers such as shutoff rods and mechanical control absorbers. The results of the flux distribution calculations were also satisfactory for both code systems.