ML20091D145
| ML20091D145 | |
| Person / Time | |
|---|---|
| Site: | Saxton File:GPU Nuclear icon.png |
| Issue date: | 07/16/1968 |
| From: | Melehan J WESTINGHOUSE ELECTRIC COMPANY, DIV OF CBS CORP. |
| To: | |
| Shared Package | |
| ML20091D132 | List: |
| References | |
| FOIA-91-17 WCAP-7219, NUDOCS 9108120372 | |
| Download: ML20091D145 (7) | |
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ADDENDUH TO SAXTON CORE III LICENSE APPLICATION by ,
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i Worked performed under S. O. DGRF-303 July 16, 1968 This document contains Westinghouse Proprietary Information and may not be disseminated in whole or in part "to any APD employa ble or others manager, creept and the tudgatin annarar.
each case by orderlot the author, This copy is numbered and individually assigned to you.. It la your responsibility to proteot this copy from dissemination, losay or theft.,
WestinRhouse Electric Corporation Atomic Power Divisions '
Nuclear Fuel Division P. O. Box 355 l Pitteburgh, Pennsylvania 1.5230 Approvedt__ _
R. S. Miller, Manager i Irradiation Technology l
9108120372 f;DIA 910702 PDR DEKDK91-17 PDR
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I. ADDENDUM TO SAXTON CORE 111 LICENSE APPLIChTION Introduction This addendum to the Saxton Core III Safeguards P,eport contains proprietary information on load f ollow f uel rod design which amplifies the description of i
these tods in the main body of the report. The types of experimental fuel rods and the ranges of rod design values are given here.
The calculational basis for nuclear and thermal-hydraulic l designs is discussed in full in the Safeguarda report and is not repeated here. Mechanical design, with the exception of a detailed listing of fuel rod var $6bles, is covered in the main report; only a brief description of assembly design is repeated here.
An evaluatjon of thermal-hydraulic and mechanical performince of these test rods which confirma that all test rods satisfy the applicable design criteria is sum-marized in this report.
Test Objective and Mode of Operation The objective of the load follow experiment is to determine the ef fect of f uel rod linear povar level, fuel denalty, fuel-clad gap and internal pressure on fission gas release, f uel swelling, and clad strain behavior under power cycling conditions. The study includes combinations of rod design , variables representa-tive of both current and developmental fuel designs. .
Throughout Core III operation the assemblies will be subjected to several power cycles each day. The lower limit of the cycling range may be restricted by Sax-ton plant capabilities, but is expected to be in the vicinity of 40% of full power. The upper limit of the cycle vill be limited to 100*. of full power, as defined in the safeguards report. In addition, mid-way -throuRh Core III life l'
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the positions of these two assemblies v)11 be interchanged! to simulate power
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- Icvel lucreases sesociated with f uel management techniques :vbleh t equire move-ment of f uel assemblies f rom low power core regions to high power ecte regions.
Load rollow Assembly _pesign The load f ollow assemblies are similar in design to previous Savton assenblies.
The arrangement of f uel rods and other f uel bundle coeponents of the assemblies is shovn in cross section in Figure 1. Three tic rods hold the removable top nozzle in place. Two tic rods are '.nconel* filled stainless steel tubes and the third tie rod is a stainless steel tube with a stainless ateel filler rod. Five water-filled tubes are used to increase the water-f uel ratio in the centet of the assembly and thus increase the power level of the adjetent fuel rods.
Fuel Rod Design A number of combinations of the variabica listed in Table I are included in the 124 f uel rods comprising the two load f ollow assemblieu. The majority of the rods are Zircaloy-4 clad. The several stainless steel rods are included to study finoion gas release and fuel swellin8 with minimited sensitivity to clad-pellet gap conductance. Twelve pressurized rode vill contain pressure control chambers located in the top plenum space to limit the range of internal gas pressure f rom beginning to end of core lif e.
The chambers vill consist of rigid stainless steel or mild qteel sleeves with brazed thin diaphragm end closures designed to rupture at pressures close to, but below, the coalant pressure. All rods with pressura control chambers vill operate at peak linear powere in the range 13.9 to 19.9 kv/ft. Five pres-nure control rods vill operate throughout Core III at peak linear powere in the range 17.8 to 19.9 kw/ft.
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Figure 1: Schematic diagram of load f ollow casembly crosa section showing general arrangement. (All peditions not otherwise noted are oc-cupied by fuel rods.)
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. o .. . ;- te Table 1 LOAD FOLLOW 7ESI ROD DESIGN VARIAlly
^* 12.11 Composition - UOy Dennity - 89.5% 1.D. - 13 rods in each assembly 921 T.D. - 30 roda in assembly E-3 32 rods in assembly C-3 94.5% T.D. - 12 rods in assembly C-3 14 rods in assembly E-3 Mixed 89.5% T.D. and 992 T.D. - 3 rods in each essen.bly
- 2 rods in each assembly Enrichment - 5.7% U-235 - 16 rods in each assembly
8 rods in recrystallization annealed condition 94 rods in stress-relief annnaled condition
.361" I.D. x .391" 0 D. - 22 rods Type 304 Stainicas Steel C. Fuel _ Clad Diame t_ral Cap ,
5.5,-7.5, 9.5 mila for Zircaloy clad rode 3-10 mile for stainless steel clad rods D. Fuel Rod Internal,_, Atmosphere air at 15 psia
! heltum at 15, 300, 400, 500 psia I
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All of tbc load follow tcut toda were designad to avoid funi molting and to
. limit end-of-lif e internal gne pressure to less than the coolant pressure l (2250 psia). The highest temperature will occur in a rod at peak design power ,
i of 19.9 kw/f t with 89.5% dense fuel, e initial f uel-clad diametral gap of 7.5 milm,' and an initial gas pressure of 15 pais. For these conditions, the beginning-of-life design peak temperatura to predicted to be 4900r. about 200 F below the melting point. With continued irradiation,-fuel thernal ex-pansion, and clad creep-down, all tend to increase the fueirciad gap conductance and therfore decrease the iual temperature. The extreme fuel-clad gap of 9.5 mile was not evaluated in combination with 89.5% dense fuel and 15 psia initial rod internal-pressure because all load follow test rods with 9.5 mil gap will be pressurised to at least 300 pata.
Other design combinations were evaluated f or initial internal gas pressures up to 500 pata, fuel density up to 94.5% T.D. and fuel-clad gap up to 9 5 mils.
Because of the higher fuel-clad gap conductance resulting from the higher pressure and because of the higher thermal conductivity of this higher density f uel, peak fuel ten.peratures were predicted to be less than 4900F.
Calculations show that the end-of-lif e internal pressure will be greatest (about 1700 poi rinximum at operating temperature) in a lead rod with 89.5% dense fuel, 500 psia initial internal pressure and 9.5 mil initial fuel-clad diametral gap.
At the design peak burnup of 21,000 MWD -- '
/MTU. fission gas realease is expected to have a minor efivet on the total internal pressure. Tha' expected clad creep-down will seduce the fuel-clad gap with the result that fuel peak tem'perature and fission gas release will be less than predicted for the case of a constant 9.5 mil gap.
liigher fuel density and anialler fuel-clad gaps are more moderate design combinations l
leading to increased fuel-clad gap conductance. lower fuct tenperatures, lower finaion gas release and lower end-of-life pressure.
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s , ., - Although an initial intertial pressure less than 500 pela vikt result in early >
life reduced fuel-clad gap conductance (conpared to a rod pressurized to 500 pal) the lower-initial pressure and greater clad creep-down yield a laver end-oi-life internal pressure than in the limiting case discuseed above.
In none of these temperature and picssure limiting combinet tons does the total clad 6 train execed the design limit of 1% in the Zircaloy clad fuel rods.
The questions of fuel temperature and internal pressure were also considered for the 22 stainless ateel-clad fuel rods in these two assemblies. The combinations of gap, fuel density and linear power have been chosen to avoid fuel melting and end-of-life internal pressures exceeding conlant pressure in the stainless steel rods, -The higher strength of the stainless steel cladding assures that clad strain at and-oi-lif e will be less than it.
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