Pellet fuel standards

TABLE 6.5 Recommended U.S. Residential Pellet Fuel Standards ... 

Pellet Fuels Institute (1995). Residential Pellet Fuel Standards." Arlington, VA, April. 

U.S. standards for biomass pellet fuels have been developed and recommended by the Pellet Fuels Institute in the United States they are shown in Table 6.5. The older standards included recommendations for moisture content and heating value, but these do not. Instead, it is recommended that the heating value be certified by the pellet manufacturer, so whatever the pellet material... 

The method was tested with two wood fuels, namely wood pellets and fuel wood. The mass flow of conversion gas was measured at three levels of standard volume flows of primary air (50,100, and 150 m n/h). Double tests were carried out at each volume flow of air. The mass-balance result is presented in Table 1 and Table 2 above. 

Three standard wood fuels have been studied (a) wood chips, (b) wood pellets, and (c) fuel wood. Figure 17 displays the three types of wood fuels. The fuel wood is from softwood, namely pine and spruce. Table 3 shows the wood fuel data. The moisture, ash and elementary analysis is carried out by an accredited laboratory in Sweden according to Swedish test standards (SS). 

The standard fuel column plenum elements have vertical channels to direct coolant to the channels in the top reflector. The volume between these vertical channels is filled with boronated graphite pellets to enhance shielding. The reserve shutdown fuel column plenum elements differ in that they contain a hole for reserve shutdown material. 

Kazakhstan has a nuclear scientific-industrial complex which was set up as a part of a nuclear infrastructure of the former USSR. More than 50% of the uranium resources of the former Soviet Union are in Kazakhstan, with seven uranium mines. Two UO2 plants produced up to 35% of the total uranium in the USSR in 1990. There are extensive facilities for producing UO2 pellets for VVER fuel elements from Russian enriched uranium. Kazakhstan has several research reactors and one operating nuclear power plant, the BN-350 fast reactor, which started operation in 1973 with a design life of 20 years. Work on its lifetime extension has the intention of bringing it into compliance with current safety standards. 1995 and 1996 were devoted to this work. In October 1996. experimental investigation on accident-proofdecay heat removal by natural circulation was carried out. The reactor BN-350 was restarted in February 4, 1997 at a power level of 420 MW(th). 

Standard BOR-60 fuel is MOX vibropacked fuel with uranium gutter, maximum bum-up in some SAs - 21 h % h.a., maximum dose - 100 dpa. The total number of fuel pins with bum-up value more than 20 % h.a. is 410 pins. Three fuel pins are under irradiation now in the dismountable test assembly at the end of 1996 maximum bum-up was 30.5 at %. Dismountable test assemblies are used for pellet MOX fuel irradiation also, the maximum bum-up for pellet MOX fuel is 17 % h.a. 

We can see there are six possible variables in this equation. Which do we know and which can be looked up Both AT values are known. The initial temperatures of both the water and the fuel pellets were given in the problem and both share the final temperature of 85°C. The specific heat (c) is not given for either the water or the fuel pellets. This is information that must be looked up, but it should be available from standard reference sources. 

The fissile isotopes of uranium ( U) and plutonium ( Pu, Pu) can be measured using active neutron counting techniques. This technique uses an external neutron source to induce fission in the fissile plutonium and manium content of the sample. The multiple induced fission neutrons are then measured using standard coincidence counting methods. The technique is mainly applied to determine the mass of in uranium-bearing samples (from LEU to HEU) in powder, metal, pellets, fresh fuel elements, and waste drums. It can be operated either with or without a cadmium liner (fast or thermal mode). 

Complete cladding failure leading to agglomeration of fuel pellets in the bottom of the canister 1 referred to as a fuel slump. The assumed volume fraction of fuel pellets In the slumped fuel region was 0.532 based on experimental measurements using standard Westinghouse fuel pellets... 

Another option is to vibratory-pack (VIPAC) ground PWR pellets into fresh CANDU sheaths. Yet another option is the Oxidation and REduction of OXide fuels) process ("OREOX"), a series of oxidation/reduction cycles that convert used PWR pellets into a ceramic-grade powder after the cladding has been removed. The powder would be pressed and sintered as "new" CANDU pellets, and loaded into standard sheaths that would be assembled into fresh bundles. All options were judged to be technically feasible, and the last option was the focus of a collaborative technical feasibility assessment program between AECL, KAERI, and the US State Department. 

Additionally, this US law adopted a prescriptive regulatory approach, requiring that the evaluation models to be used in licensing accident analysis must follow the conservative requirements established on Appendix K to 10 CFR 50 (USNRC 2014c). These conservative assumptions are stored heat 102% of peak power, low thermal conductivity of fuel pellet, conservative heat transfer coefficients, decay heat 20% larger than ANS Standard decay heat and 1200°C at the hottest chaimel. 

One important aspect, often overlooked, is the availability of suitable reference standards for testing the analytical methods. The recertification of a standard UO2 fuel pellet for uranium isotopic composition is helpful for validation of analytical methods (Kraiem et al. 2013). Exact isotope ratios were measured by TIMS and the 235U/238U ratio was recertified in six randomly selected CRM 125-A pellets. The minor isotope ratios and were also recertified and the absence of... 

---