Neutron-physical characteristics of a VVÉR core with 100% load of reprocessed uranium and plutonium fuel

Abstract

The results of calculations of the neutron-physical characteristics of three variants of the fuel load in a VVÉR-1000 core are presented: a load consisting completely of enriched natural uranium (standard fuel) or reprocessed uranium-plutonium fuel from the first and second recycles. The calculations were performed for a stationary load of the core with a four-year fuel run. The difference between the neutronphysical characteristics of a core with a full load of uranium and reprocessed uranium-plutonium fuel is discussed. An analysis of the neutron-physical characteristics did not show any fundamental limitations for a possible 100% load of reprocessed uranium-plutonium fuel in a VVÉR-1000 core.Recirculating reprocessed uranium and plutonium in thermal reactors could increase the utilization efficiency of nuclear fuel and expand the resource base of nuclear power [1]. At the present time, experience has been gained in using reprocessed uranium and plutonium separately in thermal reactors. In our country, the uranium separated from spent VVÉR-440 fuel is mixed with the uranium extracted from spent BN-600 fuel and then usud for fabricating RBMK-1000 fuel [2]. The same scheme is used to fabricate fuel for experimental-commercial operation of fuel elements with reprocessed uranium in VVÉR-440 and -1000 reactors [3]. Plutonium separated from spent PWR fuel is used abroad, mainly in France, as a component of mixed fuel (a mixture of reprocessed plutonium and depleted or natural uranium) which is loaded into 30% of the PWR core [4,5].It has been proposed that fuel made from uranium and plutonium which are separated from the spent fuel of thermal reactors be used in these reactors as fuel after other actinides and fission products are removed and enriched natural uranium is added, taking account of the compensation of the even isotopes of uranium and plutonium [6,7]. It was supposed that because the content of plutonium in the reprocessed uranium-plutonium fuel is relatively low such fuel can make up 100% of the load of a VVÉR-1000 core.To check this assumption, the neutron-physical characteristics of three variants of a stationary load of a four-year run of fuel in a VVÉR-1000 reactor were analyzed. In the first variant, the load consisted entirely of fuel enriched with natural ura-UDC 621.039.516

Physical and economical aspects of Pu multiple recycling on the basis of REMIX reprocessing technology in thermal reactors

“…REMIX fuel is fabricated from an unseparated mixture of uranium and plutonium obtained during the SNF reprocessing process with the further addition of fissile material fraction to maintain the fissile property of the recycled fuel. The main reprocessing process is shown in Figure 1 [1].…”

“…In the papers [1][2][3], it has been proposed to use the fuel made from an unseparated mixture of the uranium and plutonium isotopes mixed with the enriched natural uranium in thermal reactors. Such fuel was called the REMIX-fuel (REgenerated MIXture of U, Pu oxides).…”

“…The first two variants differ with feeding fissile material. The first is the standard REMIX fuel [1][2][3] approach and the second is close to MOX fuel where regenerated uranium is used instead of depleted uranium and the feeding fissile material is reactor grade plutonium. This makes it possible to recycle several times the total amount of Pu obtained from the spent fuel.…”

A new approach to the recycling of spent nuclear fuel in thermal reactors within the REMIX concept

“…Another reason that limits uranium recycling is the accumulation of 236 U, which is a neutron absorber. The presence of even isotopes in the fuel composition requires additional enrichment, which reduces the fuel cycle efficiency (Pavlovichev et al 2006).…”

The choice of the fuel assembly for VVER-1000 in a closed fuel cycle based on REMIX-technology

“…In papers [2][3][4], it has been proposed to use in thermal reactors fuel made from unseparated mixtures of uranium and plutonium isotopes blended with enriched natural uranium. Such fuel is called as REMIX-fuel.…”