Standard fuel assemblies

The rack consists of three sections, each of which is bolted to the canal floor and so located that the rod rests in all three. The end sections are U shaped to contain the,..rod and to permit easy insertion and withdrawal. The Tower end section.is closed at the bottom to stop the rod. The middle section supports the uranium section of the shim-safety rod. It is constructed in an angular shape and is lined with 1/32-in.- thick sheet cadmium to absorb neutrons. 

4 RCKUlatlng Rods. Four regulating rods are stored parallel to the floor in (/-shaped openings constructed at the bottom of the shim-safety storage rack. These openings are placed on the inside and outside of two adjacent shim-safety rods this permits easy insertion and withdrawal of the rods. 

---

The core of V-392 reactor uses practically all technical solutions on the advanced core of operating WWER-lOOOA -320. The prototype of the advanced fuel is standard fuel assemblies (FA) with stainless spacing grids and guiding channels which have been in operation at WWER-1000 since 1982. Originally the standard fuel was operated in the two-year fuel cycle, then the transition was done to three-year fuel cycle with the corresponding increase of average bum-up. 

RA-3 is an open tank MTR type research reactor located at the Ezeiza Atomic Centre (Centro Atomico Ezeiza), about 40 km from Buenos Aires. As in the case of RA-1, CNEA is responsible for the administration and operation of the reactor. The core of RA-3 is composed of 23 standard fuel assemblies and 4 partial fuel assemblies. The partial fuel assemblies (control assemblies) have fewer fuel plates than the standard fuel assemblies, in order to allow introduction of the control bars. The reactor is refrigerated and moderated using demineralized light water, and went critical for the first time in August 1968. 

The reactor is a typical MTR pool type reactor, using standard LEU plate type fuel assemblies. The core has a rectangular shape formed by a 5 x 6 lattice. It has 24 standard fuel assemblies, five control assemblies, and one irradiation position at the centre of the lattice. The standard fuel assemblies have 16 plates containing LEU in the form of UsOg dispersed in aluminium the control fuel assemblies have 12 plates. The core is surrounded with eight beryllium elements and 13 graphite elements that work as reflector for the fission neutrons. Demineralized light water is used as moderator and coolant. 

BP, GT and standard fuel assemblies are in grey, black and white, respectively)... 

C-E Report, 1975, C-E Critical Heat Flux Correlation for C-E Fuel Assemblies with Standard Spacer Grids, Part I, Uniform Axial Power Distribution, CENPD-162, Combustion Engineering Co., Winsor, CT. (5)... 

Operation experience of standard fuel revealed certain drawbacks both concerning efficiency of fuel utilisation, and design of fuel assembly (highly absorbing material within the active part boron-based burnable absorber low design service life one-piece stmcture). Therefore designers and manufacturers of Russian fuel for WWER-1000 have developed the advanced FA with zirconium stmctural materials and this FA is being implemented at present. 

Advanced fuel assembly (AFA) has been developed both for replacement of standard fuel at the operating reactors, and for new nuclear power plants with advanced WWER. The main difference of AFA, being the most effective as to economy, from standard fuel is application of only zirconium stmctural materials in the assembly active part. This allowed (in combination with specially developed refuelling patterns) to reduce the specific consumption of uranium approximately by 13%. Application of gadolinium burnable absorber instead of boron absorber allows to reduce this index by approximately 5% more. Application of AFA allows also to reduce enrichment of makeup fuel. Using of uranium-gadolinium fuel allows to reduce neutron fluence to the reactor vessel, to improve flexibility of fuel cycle, to exclude expenses for operation and storage of burnable absorber rods. 

Fuel assembly Hexagonal, width across flats 36.0 cm (14.17in.) Graphite density 1.74 g/cm Height 79.5 cm Standard fuel elements per column 10 Fuel rod channel diameter 1.27 cm (0.50 in.) Number fuel rod channels per element 216 Coolant channel diameter 0.95 cm (0.375 in.) Number coolant channels per element 108 Pitch between ehannels 1.90 cm (0.748 in.)... 

In order to achieve these objectives, standard coupons assembled in racks were exposed for extended periods in the spent fuel storage basins of the nine participating countries. These specimen racks were withdrawn for interim and final inspections. This chapter provides details about (a) the materials, coupons and racks and (b) the protocol. 

The reactor core is an open PWR type core made up of 213 fuel assemblies with standard PWR fuel rod diameter and a reduced height. The 2000 MWt core is located near the bottom of the reactor pool, which is a high-boron content water mass enclosed by a prestressed concrete vessel. The PIUS reactor does not use control rods, neither for reactor shutdown nor for power shaping. Reactivity control is accomplished by means of reactor coolant boron concentration control (chemical shim) and by coolant (moderator) temperature control. 

Cotpled core critical experiment lattice data were used to verify the accuracy standard reactor design codes used in determining safe sqnration distances for fuel assembly handling and storage. 

Pulsed reactivity measurements were made, in the Subcritical Eiqperiment Facility at the vannah River Laboratory. A rigid aluminum support frame maintained accurate spacing within the arrays. The lattices were tolly flooded to achieve an effective infinite H2O reflection. A KAMAN modei A-800 puised-neutron generator was located at the mhtotone 15 cm from toe core. Neutron detectors were placed in the low importance region on toe radial centerline of representative fuel assemblies. The measured fundamental-mode prompt-neutron decay constant, (meas), was determined by standard pulsedineutron techniques (Table I). 

Fuel is standard (UO2 enriched up to 5 wt% U-235) and fuel assembly design (but... 

The SFP building is also equipped with high-efficiency particulate air (HEPA) and charcoal filters to collect and filter radioactive gases that might be released from a spent fuel assembly in the event of an accident. An accident of a dropped assembly is postulated to occur that causes a breach of all fuel rods in a single assembly and release of the radioactive gases trapped in the fuel rod. Under such conditions, the dose to an individual at the exclusion area boundary (EAB) would be much less than the acceptance criteria specified in Section 15.7.4 of the Standard Review Plan (NUREG 1981). 

Fuel Similar to Westinghouse standard PWR 17 x 17 fuel assemblies, but only 2 meters in length... 

Parallel to this activity, IPEN will analyse the possibility of increasing the number of racks in the lEA-Rl reactor pool and of refurbishing a section of the reactor building in which 50 dry storage horizontal tubes are located (in which three standard spent fuel assemblies per tube can be stored), as discussed in Section 2.1.3.2. 

In addition to the racks, there are 50 dry horizontal storage tubes (where three standard spent fuel assemblies per tube can be stored) located in the reactor building. However, significant modifications will be required before any decision to store spent fuels in these tubes can be taken. Figure 4 shows a view of the dry horizontal tubes. 

---