Reactor fuel assembly

The introscopic image of power reactor fuel assembly reveals the presence the fuel elements, the tomographic image reveals their filling by fuel and location. 

The relative activity of americium isotopes for a typical pressurized-water reactor (PWR) fuel assembly are 1,700, 11, and 13 Ci for241 Am, 242Am, and 243Am (DOE 1999). The respective activity ratios for a typical boiling water reactor (BWR) are 680, 4.6, and 4.9 Ci. There are 78 PWR and 41 BWR reactors in the United States, several of which have ceased operation. Total projected inventories of these three radionuclides for all reactors are 2.3x10s, 1.4xl06, and 1.7xl06 Ci, respectively. The post irradiation americium content of typical PWR and BWR reactor fuel assemblies are 600 g (0.09%) and 220 g (0.07%), respectively. 

Of the whole amoimt of retired NSs four NSs were withdrawn from service due to incidents related to failmes in heat removal from reactor fuel assemblies while in operation (Echo-II-class NSs 533 and 541 Victor-I-class NS 610 and Alpha-class NS 900) that resulted in drastic worsening of the radiation situation in their RCs. One more NS (Echo-II-class 175) was taken out of operation due to a nuclear accident dming its repair at shipyard in Chazhma Bay. 

In part III of Fig. 1.11, the recovered uranium is recycled and reenriched and the recovered plutonium is recycled to provide part of the fissile material in the reactor fuel assemblies. Two kinds of fuel assemblies are used. One kind is the same as used in cases I and II, which consist of UO2 enriched to 3.3 w/o The annual feed rate of these assemblies is 18.3 MT of enriched uranium. The other kind consists of mixed uranium and plutonium dioxides, in which the uranium is in the form of natural UO2. Their annual feed rate is 8.9 MT of heavy metal (uranium plus plutonium), including 445 kg of recycle plutonium. The total annual UjOg feed rate is 160 short tons, which is less than for the heavy-water reactor of Fig. 1.10. 

Fig. 4.17. Japanese High-Temperature Test Reactor fuel assembly with fuel rod.

Observation of the Cherenkov radiation from irradiated reactor fuel assemblies is used to obtain qualitative confirmation (attribute testing) of the presence of spent fuel in storage by scanning rows of assemblies from the pool bridge. Characteristic patterns formed by the arrangements of rods and holes in fuel assemblies have to be observed to ensure a valid verification. A well-trained inspector can easily detect the presence of an inactive dummy assembly surrounded by highly active neighbors. 

Grimstone, M.J., Tullet, J.D., Rimpault, G., Accurate Treatment of Fast Reactor Fuel Assembly Heterogeneity with the ECCO Cell Code. International Conference on the Physics of Reactors Operation Design and Computation, PHYSOR 90, April 23-27, 1990. 

High-performance light water reactor fuel assembly concept... 

Figure 14.13 Cross section of 1000-MWj.i Chinese supercritical water-cooled reactor fuel assembly.

J. Yoo, Y. Ishiwatari, Y. Oka and J. Liu, Subchannel Analysis of Supercritical Light Water-Cooled Fast Reactor Fuel Assembly, Nuclear Engineering and Design, Vol. 237, 1096-1105 (2007)... 

M. Ookawa, S. Sakurai and K. Yamada, Optimization Method for Design of the Supercritical-Water-Cooled Reactor Fuel Assembly, Proc. ICAPP 05, Seoul, Korea, May 15-19, 2005, Paper No. 5216 (2005)... 

VAN DER GRAAF, R. et al, "Scaling laws and design aspects of a natural-circulation-cooled simulated boiling water reactor fuel assembly", Nucl. Technol., 105 (1994) 190-200. 

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