NUCLEAR FUEL FOR VVER-1000 REACTORS
Water-water energy reactor VVER-1000 is the development result of the Russian-design pressurised water reactors. VVER-1000 fuel is manufactured and supplied in fuel assemblies (FAs). FAs are designed to generate thermal energy and pass it over to the coolant flow in VVER-1000 core.
VVER-1000 reactor core comprises 163 FAs.
During reactor operation FAs are held in fixed position. Control of the nuclear reaction, maintaining the set reactor power, power-level-to-power-level transition as well as reactor shutdown – all these actions are performed by vertical movement of RCCAs (rod cluster control assemblies) in the core.
For each FA an RCCA, by design, is an assembly of 18 absorber rods (ARs).
JSC MSZ started developing and mastering TVSA design for VVER-1000 in 1997, and in 1998 it started their manufacture.
TVSA for VVER-1000 in comparison with VVER-1000 FA has an advanced design that represents (through the use of stiffener corner-pieces) an “intermediate” design between an FA with and an FA without the shroud tube.
Currently JSC MSZ manufactures the following TVSA modifications:
TVSA for VVER-1000 (498.02.000 type) – basic modification, currently supplied to Ukranian NPPs.
TVSA-PLUS for VVER-1000 (498.07.000 type) – modification with an elongated fuel stack, currently supplied to Kalinin NPP.
TVSA-12PLUS for VVER-1000 (498.10.000 and 48-98.11.000 types) – upgraded TVSA-PLUS that has plate-type mixing grids, currently supplied to Kalinin NPP.
TVSA-T for VVER-1000 (499.00.000 type) – upgraded TVSA, currently supplied to Temelin NPP in the Czech Republic.
TVSA for VVER-1000 includes the three interconnected main parts: headpiece, central part and tailpiece.
Headpiece is designed to couple TVSA with the refuelling machine during FA (un)loading. Tailpiece ensures insertion of TVSA inside the reactor as well as organises the flow path for the coolant to chill the FRs.
Between the end pieces there is a bundle of 312 FRs (UO2 and UO2-Gd2O3) with 18 guiding channels for the absorber rods (ARs) connected to the support grid. In order to increase FA rigidity and lower FA bending during operation the spacer grids and the tailpiece with the support grid are interconnected by corner-pieces of angle profile, thus making up a complete skeleton.
TVSA for VVER-1000 preserves geometrical stability at high burnups and ensures nuclear safety as well as high economic indicators for VVER-1000 reactor cores with high burnups and 4x1, 5x1, 3x1.5-year fuel cycles.
UO2 and UO2-Gd2O3 FRs are the key fuctional elements of TVSA; they are fastened to the support grid by the bottom end, while the top end stays loose.
TVSA FRs by design are zirconium alloy tubes loaded with pellets manufactured either from sintered UO2 pellets or sintered UO2-Gd2O3 pellets hermetically sealed with end plugs by welding. The use of UO2-Gd2O3 FRs makes it possible to improve power distribution across an FA as well as increase core safety margin.
FRs are produced at the automated manufacturing lines equipped with the state-of-the-art inspection and control equipment ensuring high quality and reliability of the products.
Specifications
|
TVSA for VVER-1000 core | |
|
Fuel cycle (number of cycles and cycle duration in years) |
4х1. 5х1. 3х1.5 |
|
Thermal power, MWt |
from 3000 up to 3200 |
|
Number of FAs in core, pieces |
163 |
|
Total uranium mass in core, tonnes |
from 71 up to 78 |
|
Number of annually replaced FAs, pieces |
from 36 up to 66 |
|
U235 content in U, rated, in FA, % |
from 1.3 up to 4.92 |
|
Calculated burnup (average by fuel vol.) per FA, MWt·day/kgU, maximum |
from55.5 up to 72 |
|
Water temperature at reactor inlet, °С |
290 |
|
Water temperature at reactor outlet, °С: |
320 |
|
Water pressure in reactor, MPa (kg·f/cm2) |
15.7(159) |
|
FA length, mm |
4570 |
|
Width across flats, mm |
234 |
|
Total FA mass, kg |
from 710 up to 750 |
|
Rated uranium mass per FA, kg |
from 435 up to 480 |
|
Total number of UO2 FRs and UO2-Gd2O3 FRs per FA, pieces |
312 |
|
Number of UO2-Gd2O3 FRs per FA, pieces |
from 0 up to 24 |
|
U235 content in U, rated, in FR, % |
from 1.3 up to 5.0 |