RELAP5/MOD3.2 computer code has been used to s imulate the TLFW transient in VVER-1000 NPP model . This model was developed at Ins t i tu te for Nuclear Research and Nuclear Energy Bulgar ian Academy of Sciences ( INRNE-BAS) , Sofia, for analyses of opera t iona l occurrences, abnormal events, and design basis scenarios. The model provides a significant analytical capabil i ty for the specialists working in the field of NPP safety.

06•00632 Specimen size effects in the cryogenic fracture toughness testing of Fe-12Cr-12Ni-10M n-0.24N stainless steel Shindo, Y. et al. Fusion Engineering and Design, 2005, 73, (1), 1 7. This paper examines the effects of test specimen size on the cryogenic fracture toughness proper t ies of a n i t rogen-s t rengthened austeni t ic stainless steel for superconduct ing magnet s t ructures in fusion energy systems. Single-specimen J- integral tests were performed on CT (compact tension) specimens with and wi thout side-grooves in l iquid hel ium at 4 K. The aspect ra t io (specimen width to thickness) and thickness were varied. A three-dimensional finite element analysis was also conducted to invest igate the effects of specimen thickness and side- groove on the through thickness dis t r ibut ions of the J- in tegral values. The results of the finite element analysis are used to supplement the exper imenta l data.

06•00633 The advanced high-temperature reactor: high- temperature fuel, liquid salt coolant, liquid-metal-reactor plant Forsberg, C. Progress in Nuclear Energy, 2005, 47, (1 4), 32 43. The Advanced High-Tempera tu re Reac tor is a new reactor concept tha t combines four exist ing technologies in a new way: (1) coated- part icle graphi te-matr ix nuclear fuels ( t radi t ional ly used for hel ium- cooled reactors), (2) Brayton power cycles, (3) passive safety systems and plant designs from l iquid-meta l -cooled fast reactors, and (4) low- pressure l iquid-sal t coolants with boi l ing points far above the maximum coolant tempera ture . The new combinat ion of technologies enables the design of a large [2400- to 4000-MW(t)] h igh- tempera ture reactor, with reac tor-coolant exit t empera tu res between 700 and 1000:C (depending upon goals) and passive safety systems for economic product ion of electr ici ty or hydrogen. The A H T R [2400-MW(t)] capi ta l costs have been es t imated to be 49 to 61%, per ki lowatt (electric) relat ive to modular gas-cooled [600-MW(t)] and modular l iquid-metal -cooled reactors [1000-MW(t)], assuming a single A H T R and mul t ip le modular units with the same total e lectr ical output. Because of the similar fuel, core design, and power cycles, about 70%, of the required research is shared with tha t for h igh- tempera ture gas-cooled reactors.

06•00634 Transverse buckling effects on solitary burn-up waves Chen, X.-N. and Maschek, W. Annals qfNuclear Energy, 2005, 32, (12), 1377 1390. A three-d imens ional one-group diffusion model with explicit effects of burn-up and feedback is s tudied for a so-called 'candle reactor ' . By a per turba t ion method the problem is reduced to a one-d imens iona l one, for which a soli tary wave solut ion was obta ined by van Dam in an ear l ier study. Therefore, such a t ravel l ing burn-up wave exists as well in the mul t i -d imens ional problem, which has a solitary wave profi le in the long axial direct ion and a buckl ing shape, as in usual reactors, in the smaller t ransverse direction. Two solut ions are obta ined and discussed: (i) a uniform drif t -speed solut ion in the case of a burn-up parameter , i.e. the value of neu t ron fluence associated with the maximum of k-~, adapted to the transverse buckling; (ii) a non-uni form drifi-speed solut ion for uniform burn-up parameters , where the contour lines of the wave pat tern are dis tor ted from symmetric ellipsis to sickle-shaped ones. The buckl ing effects on relat ionships of pr incipal parameters are presented.

06•00635 Using the Jacobi-Davidson method to obtain the dominant Lambda modes of a nuclear power reactor Verdti , G. et al. Annals of Nuclear Energy, 2005, 32, (11), 1274 1296. The Jacobi Davidson method is a modif icat ion of Davidson method, which has shown to be very effective to compute the dominan t e igenvalues and their corresponding eigenvectors of a large and sparse matrix. This me thod has been used to compute the dominan t Lambda modes of two configurat ions of Cofrentes nuclear power reactor, showing i tself a quite effective method, especial ly for per turbed configurat ions.

05 Nuclear fuels (economics, policy, supplies, forecasts)

Economics, policy, supplies, forecasts

06/00636 Application of candle burnup strategy for future nuclear energy utilization Sekimoto, H. Progress in Nuclear Energy, 2005, 47, (1 4), 91 98. The C A N D L E burnup strategy is a new reactor burnup concept, where the dis t r ibut ions of fuel nuclide densit ies, neu t ron flux, and power densi ty move with the same constant speed along the core axis from bot tom to top (or from top to bot tom) of the core and wi thout any change in their shapes. Therefore, any burnup control mechanisms are not required, and reactor characteris t ics do not change along burnup. The reactor is s imple and safe. If this burnup scheme is appl ied to some neut ron rich fast reactors, e i ther natura l or deple ted uranium can be uti l ized as fresh fuel after second core and the burnup of discharged fuel is about 40%,. I t means about 40%, of natura l or deple ted uranium can be uti l ized wi thout e i ther enr ichment or reprocessing. In the ideal nuclear energy uti l izat ion system, the radioact ive toxicity in the envi ronment should remain or decrease after the util ization. This r equ i rement is very severe and difficult to be satisfied. I t may take too much t ime for its real izat ion. The C A N D L E burnup may subst i tute this period. Though it is a once- through fuel cycle, the discharged fuel burnup is about ten t imes of the present value for l ight water reactors. The space necessary for final disposal can be drast ical ly reduced. However, in order to real ize such a high burnup of discharged fuels some innovative technologies should be developed. Ei ther new mater ia l s tanding still for such a high burnup or in te rmedia te recladding will be required. Especia l ly new fuel deve lopment will take a lot of time. For the t ime being a small reactor with C A N D L E burnup may be a good option for nuclear power generat ion. Even this k ind of reactor requires some innovative technologies and a long per iod for their developments . For the first stage of C A N D L E burnup the pr ismatic fuel h igh- tempera ture gas cooled reactor is preferable. Since the design of this reactor fits to the C A N D L E burnup very well, only a li t t le t ime is required for its research and development .

06/00637 Choice of nuclear power investments under price uncertainty: valuing modularity Gollier , C. et al. Energy Economics, 2005, 27, (4), 667 685. This work aims at examining how to compare two inves tment projects in the electr ici ty market . The first project is a flexible sequence of small nuclear power plants, whereas the second is a nuclear power plant of large capacity. The authors measure the option value genera ted by the modular i ty of the first project, given the uncertain future competi t ive price of electricity. Using a realist ic cal ibrat ion of the model, the authors show tha t the option value of modular i ty has a sizeable effect on the opt imal dynamic s t ra tegy of the producer , in par t icular in terms of the op t imal t iming of the decision to invest in the first module.

06•00638 De-regulated electric power markets and operating nuclear power plants: the case of British energy Hewlett , J. G. Energy Policy, 2005, 33, (18), 2293 2297. One issue addressed in a lmost all electric power res t ructur ing/de- regulat ion plans in both the Uni ted States (US) and the Uni ted Kingdom (UK) was the recovery of opera t ing nuclear power plant 's spent fuel disposal costs and the expendi tures to decommiss ion the units when they are retired. Prior to restructuring, in theory at least, in both countries, electrici ty consumers were paying for the back end costs from opera t ing nuclear power plants. Moreover, in vir tual ly all cases in the US, s tates included special provisions to insure tha t consumers would cont inue to do so after power marke ts were de- regulated. W h e n power markets in the UK were init ial ly res t ructured/ de-regula ted and nuclear power privatized, the shareholders of Brit ish Energy (BE) were init ial ly responsible for these costs. However, after electrici ty prices fell and BE collapsed, the Brit ish government shifted many of the costs to future taxpayers, as much as a century forward. If this was not done, the book value of BE's equity would have been about £3.5 billion. That is, BE's l iabil i t ies would have been about

£3.5 bil l ion greater than their assets. I t is difficult to see how BE could remain viable under such circumstances.

06/00639 IAEA activities for innovative small and medium sized reactors (SMRs) Kuznetsov, V. Progress in Nuclear Energy, 2005, 47, (1 4), 61 73. The renewed in teres t in many member states in the deve lopment and appl icat ion of small and med ium sized reactors (SMRs) is reflected in the increased activities of the IAEA' s (the Agency 's) nuclear power technology deve lopment section (NPTDS) for this trend. The paper gives an overview, summar izes in te rmedia te result, and presents major findings of the NPTDS activities for innovative SMRs, including the prepara t ion of new status repor t on Innovat ive SMR Designs, dedicated Repor t on small reactors wi thout on-site refuel l ing and coordina ted research project for the deve lopment of small reactors wi thout on-site refuelling.

Fuel and Energy Abstracts March 2006 97