ML20085D760
| ML20085D760 | |
| Person / Time | |
|---|---|
| Site: | Saxton File:GPU Nuclear icon.png |
| Issue date: | 10/31/1964 |
| From: | SAXTON NUCLEAR EXPERIMENTAL CORP. |
| To: | |
| Shared Package | |
| ML20083L048 | List:
|
| References | |
| FOIA-91-17 NUDOCS 9110170132 | |
| Download: ML20085D760 (81) | |
Text
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SAFESUARIE REPORT B3 SUPERCRITICAL TECHNOIDGY PRCORAM 9.E 4
SAXTON NUCLEAR EXPERDIENTAL CORPORATION FIVE YEAR RESFARCH AND DEVEIDPMENT PROGRAM OCTOBER, 1964 9110170332 PDR Foga 910424 D,EKOK91-17 PDR t-
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TABLE OF C0!TI'DTTS 1
.Pa.c e
,i 4 I. IffTPODUCTIO!! . . . . . . . . . . . . . . . . . . . . . . . . 'l 1 .1 i
II+I:
II. DESCFIFTI0tl. . . . . . . . . . . . . . . . . . . . . . . . . , .
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. . . . . . . . . . . . . , . . . . II-It 1 i
- 1. ODiERAL CPERATION. .
i II 2: 1
- 2. 140P U.YOUT. . . . . . . . . . . . . . . . . . . . . . . . ,
1 3 SUPr.FCPITICAL TUEL ASSE;';3LY DESCRIPTIO!.. . . . . . . . .- . 11-3: 1 ;
i 31 P4 c i er i e n,1 14eck r.i e l D; neri pti on. . . . . . . . . . . II-3: 1 i ucle' r CL racter10 tier . . . . . . . . - , . . . . . . . . . II-3: 3 32 II - ? ? k
< ;.) Th r. d erd H,"'rculic C *r m t r! n t ic r. , . -, . . . . . . .
- h. LUPD. CRIT!C/.L CDOUs!.T U.*
'! .i! . . . . .. . . . . . . . . . Il L: 1 ,
b.1 C ent rel _ Dec eript i on. . . . . . . . . . . . . . . . . . . . 11-4: 1 h.2 Proccure Tabe Assembly . . . . . . . . . . . . . . II Lt 5
. . . . . . . . . . . II L: 12 h.3 Pumpo. . . . . . , . . . . . . . .
h.h I! cat Exchangers. . . . . . . . . . . - . . . . . . . . . , . II L: 13 #
4.5 Purificct:en Equipment . . . . . . . . . . . . . . . . . .
II.L: 15 "
h.6 Specimen Holdere . . . . . . . . . . . . . . . . . . . . II h: 13 k.7 Accumultter. . . . . . . . . . . . . . . . . . . . . . . . . IT L: 13 4.3 Piping and Valves. . . . . . . . . . . . . . . . . . . . II- : 13 5 AUXILIAFY SYSTEMS. . . . . . . . .. . . . . . . . . . . . . . II-S 1 5.1 Component CoolinB. . . . . . - . . . . . . . . . . . . . . . II-5: 1 5.2 Shutdown Cooling . . . . . . . , . _. . . . . . . , . . . Il-5: 2 5.3 Coolant Makeup . . . . .- . . . . . . . . . . . . . . . . . II-5: 2 5.4 Safety injection . . . . . . . .-. . . . . . . . . . . 11-5: 2 55 Pressu: e Relief. . . . . - . . . . . . . . .- . . . . . *I- 5: 5 '
5.6 Sampling . . . . . . . . . . . . . . . - . . . . . . . . . . 11-5: 6 5.7 Decontaminatior.. . . - . . . . . . . . . . . . . . . . . . . .
!I 5: 3 3 Reactor Head thzrie Cooling System . . . - . . . . . . . 11-5; 3 5.8
- 6. RADIOACTIVE WASTE DISPOSAL . . . . . . ,_ . . . . . . . . . II-6 1 7 INSTPUMENTATION AND C0!.TFOL, . . - .- . . . . . . . . - . . 11-7: 1 7.1 Inlet Her,, Content Control . . . . . .:. . . . . . . . . . II -
L2 Flow Control . . . . . . . . . . . . . . . . - . . - . . . . 11 :.2
!. cop Pressure Controt. . . . . . . . . . , , . - . II-7' 5 73 . . . - .
7.4 Supercritical Loop Protection Systen . . . . . . . . . .. - . - II 7:
r.
Procese Instrumentation.
. . . . . . . . II-7:
75 . . . , , . . . . . ..
7.6 Radiation Monitors . . . . -. . . - . . . . - . . . .- . . . . . - II-7: 15- ,
- 8. WATER TFEATMENT. . . . - . . . . . . . - .- . . . . . . . . . . . II- : _I
- 9. ELECTRICAL SYSTD4 . . . . . . . . . . . . . . . . . . . II-9:-)
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I TABLE OF C0ffrK'(TS (Cont'd) f M
III-1: 1 III. OPEATIOfi. . . . . .......................
III-1: 1
- 1. Ih0F STAICUP . . . . . . . . . . . . . . . . . . . . . . .
III-2: 1
- 2. OPD% TION AT IU4D . . . ................. III-2: 1 l 2.1 Supercritical Pressure Operation . . . . . . . . . . . . . III-2: I 2.2 Ilot Standby. . . . . . . . . . . . . . . . . . . . . . . .
1 III-3: 1 3 LOOP S!!1TfD74N. . . . . . . . . . . . . . . . . . . . . . .
III 4: 1 4.
4.1 REF'UELING Refueling. . . ..'.@ . .FAI!(IDIANCE
. . . . . . . . . . . . . . . . . . .. . . . 2. . . . . .
III-4:
k.2 Cleanup and Decontamination. . . . . . . . . . . . . . . . I'JI h: k 4.3 Demineralizer Recin Removal and Addition . . . . < . . . .
IIT-5: 1 :
5 D4ERGENCY OPERATION. . . . . . . . . . . . . . . . . . . . III-5: 1 51 Loss of Coolant Flov . . . . . . . . . . . . . - . . . . . . III-5: 1 52 Loos of Electrical Power . . . . . . . . . . . . . . . . . III-5: 2 53 Loss of Coolant. . . ................... III-5: 3 54 Loss of Component Cooling Water. . . . . . . . . . . . . . III-5: 3 55 Bemoval of the Pressure Tube . ..............
IV-1 IV. ACCIDDir ANALYSIS. . . . . . ..................
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LIST OF TABLES No. Title Pare 11-1 Test Assembly Characteristics . . . . . . . . . . . . . II-3: 6 II-2 Supercritical loop Coolant Dystem Design Data . . . . . II-h: 2 11-3 De s ign Cod e s . . . . . . . . . . . . . . . . . . . . . . II-4: 5 k
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i LIST OF l'IGURFE I
No. Title 11-1 Saxton Supercritier.1 Loop Main , , N: J!ogram II-2 Saxton Supercriticul Loop :hui, rer,t Arrancament ,
II-3 Fuel Rod Cluster vithin Three Hexagonal Fuel Assembly Baffles II k Saxton Fuel Assembly with the Central 21 Rodo Removed 11-5 Plan Viw of Saxton Core Shwing Location of Supercritical Loop Position ,
II-6 Supercritical Pressure Tube General Assembly II-7 Saxton Supercritical Loop Sampling Equipment Process Flw Dia6 ram 11-8 Flectrical Pwer Supply Single Line Diagram Saxton Supercritical Loop Range of Operation for 3600 poig I III-l Pressure Tube Sheet Pressure l
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[UfTATIVE SCIDTifLE FOR LO3P ERECTION The following is the tentative schednic for erecting the supercritical loop in Saxton. AEC approval vill be necessary by December '21,19%
vben it is phnned to begin connections to existing Saxton systems.
October 15, 19S - Begin installation of loop components and piping.
November 6,19@ - Suspend installation for operation of synthetic crud test.
December 21, 19% - Resume installation.
January h, 1965 - Complete installation; begin loop shakedmm.
January 29, 1965 - complete loop shakedown.
February 15, 1965 - Begin fuel testing.
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I. It(fRODUCT10!( ,
The three objectives of the Supercritical Technology Progrtun are to provide a l
performnce demonstration of fuel assembly and pressure tube designs, to pro-l vide informtion not available from analytical methods or out-of-pile experi-l ments, and to provide a correintion between analysis of out-of-pile experiments c.nd actual in-pile behavior. Informtion from this progmm is erpected to I create confidence in design methods to permit design of a supercritical power-t reactor of the once-through pressure tube type.
Informtion vill be developed relative to:
- 1) development of collapsed clad fuel accemblies
- 2) corrosion and chemistry I 3) pressure tube developstat problems l !*) heat transfer and hydraulics l
Westinghouse has designed and constructed and is presently operating a super-
' critical pressure test loop to provide out-of-pile heat transfer and corrosion "
data. Many of the problems of high temperature and high pressure loop design i
and operation have been vorked out in this loop, and the information so gained vill contribute to the successful design and operation of the in.-pfle loop prc-l posed for the Saxton reactor.
The initial supercritical tests are exploratory in nature. They are designed to survey the behavior of the proposed fuel rod assembly design over a relatively vide range of experimental conditions. The initial fuel assembliec are seven-rod f
cluster designs with a nominal power rating of 80 kvt. There Will be two test assemblies of common mechanical design but with different methods of fuel rod j
I fabrication.
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I-11 2 The first assembly will use cold worked cladding material and sintered UO2 pelletsenrichedto21v/oU-235 Fot r rode vin use 16 Cr-20 Ni anoy stain-less steel as cladding and three' rods vin use Incoloy 600 as cladding. The second assembly vill use annealed cladding traterial, and vibration comiscted Two rods with 16 Cr-20 Ni-anoy UO2 powder of 21 v/o enrichment in U-235 stainless steel eladding and two roda with Incoloy 800 cladding vin be ovaged, fonoving compaction, to raise the powder density to 93% of theoretical density.
Two rods of 16-20 cladding and one rod of Incoloy 800 win be "preneure bonded" by Battelle Memorial Institute. Au fuel rods in both assemblics except those processed by BMI vill be autoclaved at 3000 psi and 700-750*F prior to firal assembly to sent the clad firmly on the fuel. This operation sill minimize rod dimensional changes in reactor service and vill assure a vrinkle-free clad.
The initial loop operating conditions win be set below maximum design values.
During the course of the program these conditions win be successivey raised to approach the design coolant outlet conditions of 100C'F at 36C0 peig with clad surface temperatures approaching 1200'F at 80 kvt operation. T1u cushed this series of tests, the loop coolant vin be continuously monitored te det ermine gross corrosion and mass transport effects. Each assembly vill be irradiated for approximately six weeks. At the end of the second irradiation period, one of the fuel assemblies vin be selected for an additional six-veek irradiation.
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IIv.t 1 2 is r e II. DESCRIPg'"
tricd
' A m,
- 1. GENERAL OPEPATION The supercritical loop consists of a test section, circula* ing p.:mps.
heat exchangers, controls and instrumenta+1on, ard auxiliury eqJpmen+ . ,
The test section in a re-entry type preocure tute which contairs the fuel assembly and is incerted into the reactor ccre throt.ch c:.e of the reactor head removable ports. In operation, the fuel assembly cperates as part of the Saxton core by utilizing the Saxton react or's neut ror flux to produce fission energy. This energy is removei from the fuel by circu.
Inting supercritical vater through the pressure tube. The heat ed vster is then cooled and returned to tne test secticn by circulating pumps.
A simplified system flow sheet is presented on Figure 11-1. Icv pressu e, 1crd temperature water from the demineralizers is injected into tLe high .
pressure loop and circulated by means of the loop pump. Frier to e*tering the pressure tube, the coohnt is preheated in te irp erchanger and then brour.ht to the desired pressure-tuce irlet terperatze eenditio*.s- ty ar.
electrical heater. The cochnt en4 ers the pessoure
- ute near the tep,.
flovs dovuvard in a thennally baffled ansulus to tne bottom of the tube and then flows upward thecush the fael asaembly.
The heated coolant leaving the pressure tute is c;ciei first it the itten changer and then in the high pressure eccler to prevent flashise. dkring pressure reduction. Next. the coe:an* passes threugh the presste r-rencing valve and into the lov pressare cooler fcr fur *.her coclirg a:d pessve reduction. The resulting low pressure st rea:n fit.s thro'.gh 4 %e prificatio*.
equipment where gases, ionic impurities, and cerrosion per dacts are remcVes.
Condensate pumpo return the coolant to the Icep pump.
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II-21 1
- 2. IOOP IAY0t/I The supercritical loop, with the exception of two 3/8-inch sampling lines which are routed to the Saxton sempling room, is located completely within the reactor containment vessel. Locations of the supercritical loop components within the containment vessel are shown on Figure 112.
All loop controls are located outside the vapor container in or near the These controls are arzsnged so that they my be reactor control room.
utilized without interfering with nonnal plant operation.
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II-3: 1 3 SUPERCRITICAL FUEL ASSFXBLY DPE2CRIPTION 31 Physical and Mechanical Description Tne supercritical loop fuel is enriched UO 2 , either eintered in the form of penets or vibration compacted and svaged or vibmtion compacted and
" pressure bonded" by BMI. Table 11-1 gives fuel rod design parameters.
The penets have dished ends to offset the effects of great.er thermal expansion in the center. A void is provided in the upper end plug of each rod to accomodate fission 6as buildup. The fuel is clad with seamless and cold drawn type 16-20 stainless steel or Incoloy, with nominal van thickness of 10 5 mila. The folleving assumptions are implicit to the clad design calculhtions (a) fuel assembly power output is 80 kv; (b) mrocimum cold diametral gap is 0.001 in following loading of pellets or svaging of powder) (c) cladding mechanical properties correspond to approximately 8 to 10% vork hardening fonoving svaging or pellet lor. ding. Specifications ut sd for quelity control and inspection are the same as those used for procurement of the normal Saxton fuel tubes as well as those for the Yankee and SELNI reactors.
The cladding vin rely on the enclosed fuel fo/ support against the coolant pressure. The fabrication method for the penets vin result in a very small diametral gap between the fuel and the clad (-0.001"to 0.001") .
Tonowing fabrication, an fuel rodo except those proces ed by BMI will be sub.)ected to external pressure of 3000 psi and increasing temperature up to 700 F prior to installation in the reactor. The purpose of this pressure-temperature exposure is to remove any initial gap fonowing fabrication and to insure that the clad is seated firmly against the fuel without vrinkle formation. Is the fuel rod is cooled fonowing this exposure, the clad vin contract faster than the penets, and the clad win be straine<1 in tension from 0.06 to 0,25%.
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II-3: 2 As the fuel rod is subjected to the loop pressure and the tem-perature is brought up to zero-power conditions, the tensile strain in the clad vill be relaxed and .cor.verted to a conpressive strain by the coolant pressure.
As the fuel rod is taken fram zero power to full power, the yellete vill expand more than the clad, and the clad will be strained in tension. During subsequent cycles, the clad vill experience tension "
and compression straining. The total strain vill be between 0 36 to 0 52% for cycling betveen zero and full pover. The maximum risstic strain range vill be approximately 0.22%. For a complete startup and shutdown Cycle, the total strain vill be between 0.6 to approximately 0 7'f. Using Incoloy otrain fatigue data at 1300 F, l
160 such cycles vould be required to cause fatigue failure.
Seven fuel roe form the fuel assembly, as ebovn in Figure II-3 One rod is at the center of the assembly with the other six cur-rounding it. The outer six rods are spiral vrapped with vire 0.03 inch 0.D. at a 10-inch pitch; the center rod is not vrapperi. he vire vraps separate the fuel rods and prcnote coolant mixing. The The fuel wire is of the same material as the clad which it is on.
assemblics are bolted to the upper g-id and bolts tack-velded in pince. The rods are slipped into the lover grid, which restricts radial movement while allovir.g axial expansion.
The rod cluster is contained vittin three form-fitting hexagoratl fuel assembly bafflee (1), E and F) in Figure II-3 'Itese baffles esuse the inlet flov to enter the fuel assembly at the lover end of the core ar.d minimize regenerative he.at transfer. Tte fuel assembly biffles are velded at the top to the upper grid. The inner baffle F, shaped to provide the
II 3: 3 proper cross section for flow in the core, is alco velded at the bottom to the lover grid. Outer baffice D and E are dimpled for proper position-ing, and an interference fit between dimples and baffles produces radial pressure which helps in centering the fuel assembly and prevents thermal bowing and fretting, With the fuel rods and fuel assembly baffles suspended from it, the upper grid is hung from the outer fuel assembly hanger baffic. There are three fuel assembly hanger baffles. The heavier outer baffle is velded at the top to the spring guide and at the bottom t; the upper grid) the inner two are allowed to expand freely at the top. These baffles separate inlet from outlet flow and minimize the regenerative heat exchange between the inlet and outlet water above the core.
The fuel assembly, the fuel assembly _ baffles, and the fuel assembly hanger baffles are bolted to the pressure tube baffles described in Section 11-4.
The assembly is fitted into the pressure tube.
The Saxton fuel assembly, into which the pressure tube is inserted, has 21 rods removed, as shown in Figure II h. Special spring clips with fingers to support the remaining fuel rods are velded to the Erid in the opening formed by the removal of the fuel rods. The pressure tube vill be inserted into this opening.
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32 Nuclear characteristics l
The supercritical pressure tube is installed in the modified Saxton fuel assembly in the location desi6nated by the numeral N-4 in the Saxton core cross section diagram, Figure 11-5 The supercritical fuel assembly c
depends upon neutrons from the Sa;; ton reactor core for generation of its power and therefore-behaves as a segment of the core. Power generation in the supercritical loop is dependent on the power level of the Saxton reactor core region adjacent to the pressure tube.
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i e II-3: 14 The Gaxton reactor reactivity coefficients vill be essentially the same with the pressure tube or du:=y plug in the core. The reactivity coefficients for the Saxton reactor resulting frcm moderator variations in the super-critical loop are as follovet Flooding coefficient = 5 0 x 10*b bk/k for Saxton reactor with 0 variation of supercritical coolant from 950 F, 3500 psi to 3007,100 psi conditions.
Temperature coefficient = -1.1 x 10-6 b h/k for Saxton reactor per O F
supercritical loop average coolant temperature increases.
Pressure coefficient = 0.25 x 10-6 bk/k for Saxton reactor per psi supercritical loop pressure increase.
Density coefficient =0.69x10~5bk/kforSaxtonreactorperper cent supercritical loop coolant density inerence.
The power distribution within the supercritical loop fuel was calculated by the PIM3 and SLOP-1 digital computer codes.
33 Therrmi and itydraulic characteristics The themal and hydraulic characteristics of the supercritical fuel assembly are included in Table II-1. The installation and operation of the supercritical loop does not significantly affect the thermal and hydraulic characteristics of the Saxton reactor core.
There are no DND considerations in the operation of the supercritical loop at power because the coolant is steam at supercritical conditions.
During hot standby operation of the supercritical loop, the loop inlet temperature and operating pressure are approximately the same as that for the reactor. Under these conditions, the supercritical fuel assembly power vill rise above its normal value because of the increase in coolant density. For the 115 kvt assemblies, this rise in pc.ter vill result in a
II-3 5 peak specific power lower thar. the 16 kv/ft which previously has been shown w be safe for the special opiked Saxton accembly in the center of i thecore.(1) The heat transfer characteristics and physical description of the pressure tube baffles are included in Section II-4.
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1 (1) Addendum No. 2 to the Phase I Saxton Safeguards Report.
11-3: 6 TABLE II-1
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TEST ASSDSLY CHARACTERISTICS
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Maximum Power Level (Dec1gn) 115 kvt i
21% for 80 kvt operation Enrichment
- for 115 kvt operation 3 Coolant Flev:
Design 6750lb/hr Minimum allovabic at 80 kvt 1 4500lb/hr 115 kvt 6750lb/hr Mass velocity thru fuel 2 assembly at 6750 lb/hr (nominal) 2 x 106 lb/hr-ft 6.151 kg Quantity of UO2 in the supercritical loop (7 rod assembly) 12.826 kg Quantity of UO2 in the 21 rods removed-from the Saxton fuel assembly 383,000 Btu /hr-ft 2 I Heat flux at 115 kut: Maximum e Average 159,000 Btu /hr-rt l
l i (1) Based upon 1200*F maximum clad surface temperatures and 930*F inlet coolant temperature.-
(2) Case chosen for testing. Reactor power is assumed to be 20 Wt for calculation of fuel power output.
(3) Assumed design limits of operation of loop.
- To be specified after 80 kV operation.
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' Het.t t ransfer surfste P.'7 4 ft ;
Temperature:
Coolant, fuel assect'ly c,ut le+ 'OCCCF maximum at 115 kvt Coolant, ir.let to fuel 930 F assembly - maximum at 115 kvt 0
Coolant, inlet to thimble - 967 F l
maximum at 115 kvt Maximum clad surface temper . 1200 F ature (cican vall)
Fre .JLre tu e het spot 6610F temperature C
Maximum center of fuel 3330 F 4 emperat ure Fuel Aaoembly:
, .ive rod ler.gth 3 ft.
Fuel rod cutside diameter C.k50 in.
Wire wrap diameter C.C50 in. ,
Clad thickness C.ClC 5 in.
Flow area C.00337 ft Hydraulic diameter C.00975 ft Rodo per assembly 7 Rod lattice 0 500 in.
Fuel rod maximum specific pc'ver 13.2 kw/ft at 115 kst, nemal operation Wire vrap pitch 10.3 in.
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i Iength 0 76 ir.: hec :.a h re j
L 0.D. C.k29 inchea Fuel Stack Expansion:
Center rod 0.67 per cent '
Feripheral rods 0 79 per cent (k) Caleulated-value icr a three taffle desig.n.
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- Baffle Insulation:
Number vator layers adjacert 3 to thimble
!1 umber vater layers enclocing 2 I hanger tube and fuel assembly l
Water layer thickness 0.020 in.
Thimble Pressure Dropt
- 140 psi
!bximum Hot Channel Factors:
2.k1 F
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1.18 I
I Fg Film rise T 1,81 Fg; 1
- 4mre weress-*'ee--egMr'we -melis- menswww -mees-w nse hmguis,-
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1 II-4: 1 i l
l 4 SUPERCRITICAL CODIAlff SYSTIM :
i 4.1 General Description The supercritical coolant system is that portion of the supercritical loop that handles and treats the loop coolant during normal operation.
It consists of the pressure tube, pumps, heat exchangers, purification equipment, accumulator, specimen holders, instrumentation and necessary i
piping and valves. Detailed design data nregiven in Table 112. ,
Applicable design codes are given 'n Table U-3 l l
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% , *.6 (;-2 SUPERCRITICA . Gyl f.! % /J SYSTDi DESIG!4 DATA .
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Pressure Tube:
Coolant temperature at ov:let (max. at 115 kvt) 1000 F 0
Design temperature 675 F 4000 psig Design pressure, internal 2200 psig ,
Design preosure, external "
3600 psig Operating pressure, internal 0.D.(Zircaloysection) -2 75 in.
I.D.(Zircaloysection) 2.03 ire.
3 iHeating(maximum) 1.08 x 106 Btu /hr-ft Heat leakage thru Zircaloy portion 25,000 Btu /hr of pressure tube Heat leakage thru ctrinlesr steel portion 141,000 Btu /hr of pressure tube
- 1 Primary and Standby Coolant Pumpst 2000F Design tecperature 5500 poig Design pressure Des 16n flow rate Primary pump, full rpeed 15 gpm Standby pump, full speed 5 3 gpm l
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Condensate Pumpei
-Design temperature 300 F I Design pressure 150 peig 16 gpm Design flo rate f
Heater:
Design temperature -1030 F Temperature - fluid inlet (max.) 760 F Temperature - fluid outlet (max.) 10150F Design pressure h000 psig
- 34,000stu/hrofthislossisduetocoolingofnozzleheadpenetration.
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Interchanger:
1030 F Design temperature, shell Design temperature, tube 1030 F 4h00 psig ;
Decign pressure, shell 600 psig Design differential pressure, tube (external)
Ligh Pressure Cooler: i 200 F Design temperature, shell 0 Design temperature, tube 700 F 150 peig
- Design pressure, shell 4h00 psig Design pressure, tube Lov Pressure Cooler:
200 F Design temperature, shell 0
Design temperature, tube 550 F 150 psig Design pressure, shell
.1C00 psig Design pressure, tube Deaerator: '
Design temperature 330 F 85 psig Design pressure _
1 Demineralizer:
200 F Design temperature-150 psig Design pressure Filter:
Design temperature 200 F 150 psig j Design pressure Accumulator: 0
-Design temperature 150 F 5000 psig-Design pressure
II-4: 4 a
t Piping S1:es lleater to interchanger 1-1/2in. I i . 1 in. ;
Other loop piping ,
System Volumes: I 245 gal.
Total volume (including fv1.1 head tank ,
and full deaerator) 80 gal, Operating volume (excluding head tank, deaerator at normal level) ;
20F/ min, ,
System IIeatup P, ate (Hominal) I l 615F/ min, (Max. Allowable) l 1'
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- meti me- ye vapr. e e re M p-ww-y -*+pyr w'9 p ge-"gww+-79p'e*m- & p +wi'+g+, y 5 gey e p qp+ww p tsg ma - 'ig gney yygg ww __ _. , , . _ . , , , swW Tr vyA mli$= +p- w e q 'wwe 4* P-*wpWWN T-Fw-
II 141 5 i
1 d
I TABLE II-3 ,
DESIGN CODES i .
-l ASME VIII*, Nacicar Case 1273N Pressure Tube Loop Pump None Standby Pump None Condensate Pumpa None Heater Shell ASME I**
Interchanger ASME VIII, Nuclear Case 1273N ,
High Iressure Cooler ASME VIII, Nuclear Cace 1273N LW Pressure Cooler ASME VIII, Nuclear Case 1270H (Secondary Vessel)
Deaerater ASME VIII Ace culator ASME VIII-Specimen Holder Shell ASME I Piping ASME I
- ASME VIII - American Society of Mechanical Engineers, Boiler and Precsure Vessel Code,Section VIII,_19(2 Edition.
- American Society of Mechanical Engineers, Boiler and Pressure
i
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_ _ _ - _ _ _ ~ . _ _ _ , _ _ _ _ _ . _
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II-41 6 f l
l 16 . 2 pressure Tube Accetbly r
The pressure tube assettly, sho n on Ficure II-6, is of the bayonet re-ent ry
- ype . Coolant at 3600 psig and 6CC F to 975 F enters t'e l
l pressure tube throut,- the lower juuper and flovo devnvard through the annulua fctned by the pressure tube baffles and the fuel acaembly bsffles.
At the lover end of the pressure tube, the flev direction is reversed to I
j pass upward throuch the fuel necembly and inner f ael assembly hanger baffles. The coclant leaves thrcugh the top jumper at temperatures up to 1000 F.
A Marman Conoseal pipe joint serves to support the pressure tube assembly and prevent lenhage cf reactor prienry coolant. This joint is to be serviced by remote ceintenance tools. Inlet and exit jumper piping con-nections are pade with Grayloc fittings. A remote raintenance tool is also feasible for thes? fittings and vill be used if necessary to limit main-
- tenance personnel exposure. The precoure tube areembly consists of five components; the connect or body, pressure tute extensicn, the head adaptor flange assembly (each three of AISI Type 316 stainless steel), a co-extruded transitien joint between stainless steel and Ziresloy-4 and the Zircaloy-4 pressure tube. The design code is shown in Table 11-3 4 The transition jcint is velded to the Zirealoy pressure tube, and the reculting assembly is cold worked 10 to 1% to achieve required strength.
The rough nochined onnecter body is velded to the head adaptor male-flange. After final machining operaticne, this assembly'is velded to the trar sition joint to form the ecmpleted Frt ssure Tube Assembly. .)
Cotrec+.cr Body I
The connector bcdy is designed for 4000'psig and 10CC F vith atmospheric pressure outside. .A-three-inch nhickness of insulatio7 is provided. The i
l.
l--.
II-4: ?
i i
inlet and cu*.let nozzles are machined frcm solid stoch ac part of the cc.necter Lcdy, They are spared opproxica* ely 16 inches apart to reduce A refueling .
i heat transfer and thermal c*.resses tetween the '.vo areas.
part is lo:ated in the upper end of the cer.nect:r body and is cealed with f
a Conoccal cachet. A ring and six jack screws, made of W-Sk5 Steel, serve
- o hold the Contceal male flange it. place. Each Jack screw is tightened to 95 pound feet tcrque t o prelosd the Conostal gasket with sufficient axial compressien t o resist any gacket movement du*ing creration at kN.D poi. Ccnoseal clamp and sleeve flange ic of AISI Ty;e 316 stainless c zel.
Hydrostatic thrast due + 3 kCOC psi internal pressure and the refueling port spring is 26,500 peu.ds. Axial port otress in the threaded area frce this l
thrust ic 2700 psi. Ring 1.h*end chear stress is 4500 pai and jack screv tearing strece and thread shear stress are 18,460 pri and 370^, psi respec-t.tvely. The jack screv tearing stress in equal +o 1/2 cf the stress required to produce 1C$ relaxaticn in 1000 bcurs in V-545 stainless steel at 1100UF. W-$L5 tias choser. fc
- ring and jack screws because it tatchec
- ne coef ficient of thermal expa asion of the refueling port male and fecnle 0
fianges. In addition, it poss : sees high strength 'at -LOC 0 P; typical creep rupture stress at 100,C(C houa s at LOCO F is apprcrinntely 80,.00C psi.
A ball-cone seni, just telev the cutlet nozzh. supp rts t he fuel assably and prevente the bypass _of inlet coolant ar:vd t te fuel assemtly to the exit jun:per. To secu*e a positive sealin6 agavs1 hydroc+ atic_ pecsre,.
a refuelir.g port spring is provided in the top ci cne presaure w be assembly which is desigr.e4 to provide a mi .itra seali:.g force of 60 lbs.
The spring force is based cn *he filievir.g ass'aptions:
Total thrust due to hydrM'atic preestre - 530 lbs.
1)
- 2) Weight of internal parts' _
+ 75 lbs.
- 10 lbr.
- 3) Bhoyant force Baffle frimica force 125 lbs.
-4)
Minimum spring force at tempera +ure =+ 650 lte.
Si-4 -60 its,
- 6) Minimum net sealing force ,
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II k! 8 Hend Adapter F1ance Assembly The head adapter flange assembly supports the pressure tutie while connect-ing it to the Saxton Reactor Head Adapter. The head adapter flange assembly screws into the Saxton Reactor Head Adapter and in seal velded.
The assembly in velded to the connector tube. The cale and female sections of the acceably are joined at the Conoscal joint and clamped together. The assembly parts are constructed of Type 316 stainless steel.
Pressure Tube, Pressure Tube Extension ai.i Transition Joint The portion of the pressure tube assembly extending within the reactor vessel vill not be code stamped because it is completely contained within the reactor vessel which is the ultimate container for reactor and icop coolant. Furthermore, Zirculey. h is employed and is not a code approved mterial. This portion, however, is designed to meet the intent of Section VIII of the ASME Pressure Vessel Code and Code Case 1273N as outlined below.
Sections III-1, 2 and 3 of this report describe normal loop startup, operating, and shutdown conditions. Initially, the loop and reacter ara brought to 2000 psi and 530 F together.
Differential pressures across the prtEssure tubes are small during this time. The loop pressure is then increased.to 3600 psi normal operating pressure followed by increasing loop temperature to test inlet temperature.
The reactor is brought to power. Nomal cperating conditions have thus been established. These conditicca are: 3600 psi internal pressure and 2000 '
psi external pressure for a enximum difference in pressure between the inside and outside of the pressure tube of 1600 psi; 675 F Zircaloy h pressure tube taximum temperature (including gamma heating) and 600 F' pressure tube extension maximum temperature. Reverse procedure is followed during loop and reactor shutdown.
_ _ _ _ __ _ _ _ ._ _ _ _ . - . , - , . _ . . _ _ _ . - _ _ . - _ _ _ . _ . . - - - . _ _ _ . . ~ _ . _ , _ _ .
II-4: 9 Paragraph UO-21 of ASME Code VIII specifies the fonwing procedure to determine minimum veccel design pressure: "U3-21 DESIGN FRESSURE.
Vessels covered by this section of the dode shan be designed for at least the most severe condition of coincident pressure and temperature expected in nomal operation. For this condition, the maximum difference in pressure between the inside and outside of a vessel, or between any tvo chambers of a combination unit, shall be considered (see Faras. LU-98 andUA-60(b))." ,
The most severe condition of coincident pressure and temperature expected in normal operation is 1600 psi at 675 F in the Zircaloy-4 pressure tube and 6000 F in the pressure tube entension. Hovever, for additional con--
servatism, the following conditions are used for design. The pressure-tube extension and the Zircaloy pressure tube are designed to withstand 4000 psig internal pressure and zero external pressure at the above listed temperatures and 2200 psig external pressure and zero internal pressure at the above listed temperatures.
The pressure tubs extension vall is based on 2200 psig external pressure at 6000F. Allowable stress for SA 182 Type 316 stainless steel for these conditions is found in Section VIII of the Code to be 15,950 at-6000F. The maximum outside diameter is 2.8h1 in, and the minimum vall thickness is calculated from Figurr U3-31 of Code VIII to be 0.381 inches.
The specified minimum vall thickness is also 0.381 inches.
The Zircaloy pressure tube vall thickness is based cn 2200 psig external 0
pressure at 675 F. Allevable stress for Zircaloy L for these cenditions is determined in accordance vith Appendix Q in ASME Code VIII with the exception that the allowable stress is based on 1/3 the specified minimum ultimate tensile strength at dMign temperature. This is consistent with the rules for establishing aL ..able stress values in the recently pub-I l
liched ASME Boiler and Pressure Vessel Code, Nuclear Vessels,__Section III, Appendix II. The allowable stress is, thus, found to be 17,.C-00 psi at
.6750F. The maximum outside diameter is 2,753 inches and the minimum vall l
[
. . . ~ . . . . . . . . . . . . . _ , , .
II h: 10 thickness is calculated from Figure W31 ef ASME Code VIII to be 0.353 The l inches. The minimum specified vall thickness is also 0.353 inches.
ca3 cult.ted minimum collapse pressure for the Zircaloy pressure tube at design temperatur< 9,250 pai, indicating a saf ety factor of greater than four. It ' nerefore, felt that the der,ign meets the intent of ASME Code,Section VIII. ?
During fabrication strict quality control and inspection procedures vill be adhered to.
All velded jcints vill be fully radiographed to Code rtandards. A u pressure containing materials vi n be ultrasonically inspected. Welder and velding procedure qualifications vill be based on ASME Code IX.
Fonowing fabrication the entire pressure tuoe assembly vill be hydre-statically tested in accordance with paragraph 099 of Code VIII.- The assembly vin be subjected to separate internal and erernal pressure-tests.
Presrure Tube Baffles The three pressure tute baffles are fabricated from stainless steel sheet metal and are provided to minimize the loss of heat to the Sarton- re ntor primary cualant and to maintainithe Zircaloy pressu-e tube vall' tempera-ture at or below an acceptable wlue cf 675 F. - This is achieved by the insulating effect of three 0.020 inch thici layers of stagnant water. The baffle design temperat.aes are based on 950 F inlet, eschnt temperature.
The three baffles are fastened to the pressure tube baffle support cylinder at a slip joint, and the support cylinder is velded to the spring guide.
The support cylinder has six slots to allow inlet flow access to the down-flow channel formed by the pressure tube baffles and the fuel assembly l
f hanger baffles. Tne ' lower grid is bolted to the pressure tube baffle.
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The pressure wbe taff;es are boltei no tne lover Erii assembly. This arrargemer.; silf fens the ir.ternais assembly and provides fc r the ec.itain-
'me.t of fissicn yreducts ir 4he ever.t er a ::ai failure therety minimizir.g
- he coritamination of the Sax +,cn reac:ct fue[ pit. In addition, the step in ice pressure tube internal diameter immediately above the fuel assembly allove tne fuel assemb y taff;es to pu)1 free of the dimple interference fit within a ch0M distance ec as to facilitate Qe rencval of the f tterr.a s in it e even* it is revdred.
The two cu* er t affles sre cubje:+ ed to equal interns; and ext er-al pressve,. ar.1 the thiektess of these baff.es is set at C.011 1r.ches.
However, the ir. er bsff_e (Faffie ' C'"i is s.fcjected to a differettial radial ;:ese,, e resulting f7 *m the c:cle '. press.ce dr:p 're veen tube iniet sr.d f':el assently it.let. The baffle se desigrei
- o vi-t-c*,.ani ihis differen*,1al ex4.nnal pressue with07 buckling. Tc: an es+1ma+.e3 pressve drop cf 4 yei ai d a cafety fact: 1 cf 6 the minimum
' val _ *.hicenes cal.f_ated ac c.rding to ASME VIII fer 310 s+ ainless steel at 93C0 F in c .c 32 1.ches. The minim.cn ir.ner wall is specified as f. 32 1*etes.
Dimples are prcvided on each bsf fie for proper peettic".ing and align-C
'- ment. The dimples a.re pi . .r.ei at 1.?j in:ces avially and 11C - mciaMy l st a pa?.icu~ ar c ess-sec'icn. F:vever; the dimples en s:.y : e cy:ss-sec+.icc are t' tW:1 6d wi%n respe .- it %e dimples et Ve stjren .
l I
cross-sactic*..
i l
Ine bafrie ar.d dimple dim.ules e e 8: a n as .: r er2.c, ir -r in:e- f eren:e f1*. betweer *he dimp .es and cne taffle an1 the it side diame*er Of the next outer ehei?_. This will r(d.0e fret *ing which woCd resah if a .
- learance existed.
l
- .__ _ . . -_ . . . . . . ~ . _ _ . _ _ . . _ . . . . _ . _ _ , . _..-._ ,___.- - __. _ .,,,...,._,, -._,..~.. m_,-._,
_ _ _ _ . . - . . . _ _ _ _ ~ . _ . _ _ _ _ _ . _ _ _ . _ _ . . _ . _ _ . _ . . . . _ . . _ _ _ _ . _ . _ . .
II-4: 12 The dimple in+ erference cal *'n the baffles to deflect rt.diallyf thus inducing a radial fer e cn +.he taffles. This gives rise to a frictica force when:
- 1) One baffle is inserted into another ,
- 2) The baffle assu.bly le inserted into cr pulled out frem the pressure tube 3)
One baffle has a expansicn relative to *.he other due to a temperature differential.
It is estimated tha'. fcr case (1), approximately h0C lt. force vill be recessary to overcome the fric'.icnal force with an arsumed coefficieu of friction of C.2. Tr.e maximum stress 1-duced by the process of insertion-is 10,00C psi.
As a In case (2), a maxima frictior.al fer:e of 115 lb. is developed.
result ,
40 lt, force will be necessary to insert t.ne baffle sseembiv stil ,
tube.
270 lb. force vill te t.eeded to pull the raffles cut of the prec. .
'xial compressis u os ;f-The process of rencval vill induce a maxi.-
1700 psi in the oter taffle.
t For case (3), the 1 1 :ei stress-ranges4 . 13,00C psi.- The radial-temperature gradient-tetwter..barfles res.uts in-axis 1 differential expansion. Allowan:e is made fcr this- by tolting ar.T.un- baffles at the tct*.om sc- the fuel nerembly and allowing then to expand freely. at the top where a slip ,)oint is. provide'l to accom:rdate t he differential expansion. -.
All stress levels are less hac yieliit,g ord h211ng 'e'.reng*hs.
4.3 Pops
'Ihree electrically niven p;anps are 3r:,vided to supply coelsnt to the pressvre tute. Sc + wc-speed lecy pump supply 15. cpm at T ,ll: speed wi* h
.- . - ..-.-. .- . . . . . - . ,,.~..-..-..-..-...-.-_-.-a-.-_.-----.-....
II-41 13 discharge pressures up to 5000 psig. At half speed, the loop pumps supply 7.5 Epm at the some discharge pressures. The standby pump is provided as a reserve in the event of loop pump malfunction. The second loop pump is physically piped into the system but is not connected electrically.
In the event of failure of the first pump, it is electrically disconnected from the system and the second loop pump hooked in. The standby pump provides coolant flow during this operation.
The single-speed standby pump deve' ops the same discharge pressure as the loop pump with a flow of 5.' gym. 'he standby pump is energized- by the loop flow controller or manually from the plant contr:1 room. Electric power for the loop pump is provided from the supercritical loop 40 V bus.
Electric power for the standby pump comes from the motor control center of the Saxton reactor electrical system. Sach pump.is a triplex positive-dici.alcement type, with integral check valves. All parts in contact with the coolant are fabricated of austenitic stainless steel or equivalent corrosion-resistant material.
A leakoff is provided on the pu=p packing gland to collect coolant before it can leak to the reactor containment atmosphere. The coolant leakage is i
piped through a strainer to pump suction for return to the loop. The pu=p shaft is made long enough to prevent the oil-vetted portion from contact-l ing the pm:p packing, l
1
! 4.h Heat Exchangers i
Heater i
l i
The heater raices the coolant temperature to the required pressure tube l
inlet conditions and provides control to maintain this temperature constant.
l The total heater capacity is 650 kw. The unit consists of forty-tvo l
i individual heater sections arranged in three identical parallel paths.
Each section censists of a straight run of pipe containing a s'tagle l-l 1
t
. . , . . n--,-.---, .,,,--,,v ,.. - , , , - , , . .- , . . - . , . - . , , . . . . . - , . - - - . , . . , . - . . . ~ . - - , .
II-4: 14 immersion-type electric heater element. Coolant flovs through the annulus forced by the heater element and the pipe. The pipe is austenitic stainless steel and the heater sheaths are Inconel. All piping joints are butt-veldeS or screved and seal velded. Electrical connections for the individual heater elements are made through a high pressure seal. Spt ce s are velded to the heater sheath to assure concentricity of heater tube and outer pipe. 11 enter power is supplied from the supercritical loop 440 V bus, lleater output is controlled by a saturable reactor which varies heater voltage and current. The saturable reactor is a variable impedance device with two vindings, one for a-c power and one for d-c control on an iron core. The a-c vinding is connected in series with the heaters. Le .
1"pedance is varied by controlling the magnetic caturation in the iron core. A complete range of control of a-c power can be obtained in a smooth stepless manner by varying a small amount of d-c power.
' Interchanger The interchanger recovers heat from the coolant leaving the supercritical i'uel assembly by heating the inlet stream. This unit consists of three double-pipe coils connected in parallel and arranged concentrically about the vertical axis. The hot coolant stream flows through the inner pipe tad the cold stream flows through the annulus. The interchanger is made wstenitic stainless steel with all joints velded. Spacers are pre 'ided between inner and outer pipes to ensure concentricity.
High Pressure Cooler The high pressure cooler reduces the temperature of the interchanger tube side stream to permit pressure reduction without flashing. The unit con-sists of a vertically-oriented double-pipe coil, with the loop coolant in the inner tube and component coo." -e. water in the annulus. The inner pipe
-. . - . . - . - . - - .-. . .. - _ . _ . _ _ _ .- . _ . . - , - ._- _-- - - ~ - ~ _
II-4: 15 is made of austenitic stainless steel and the outer pipe is of carbon eteel. All jointe are velded. Spacers are velded to the inner tube to assure con::entricity of the tvo pipes.
Low pressure Cooler _
The low pressure cooler further cools the loop coolant after it passes through the pressure-reducing valve. It also serves as a letdown device The by reducing coolant pressure to the deaerator inlet conditions.
unit is a vertically oriented, double-pipe coil mounted concentrically with the high .ressure cooler. Loop coolant flows in the inner pipe and component cooling vater in the annulus. The irtner pipe is made of austenitic stainless steel and the outer pipe of caroon steel with all joints velded.
t k.5 Purification Equipment General Description The purification equipment is designed for full- flow and consists of a deaerator, a demineralizer, a filter and two condensate pumps. Cooled, low pressure water discharged from the low pressure cooler flows through a spray nozzle into the deaerator, where essentially all radiobtic and j fiscion gases are removed. The deaerator operating pressure is maintained below atmospheric pressure by a vacuum pu=p which removes the gases together-with a quantity of diluent steam and discharges the mixture to radioactive -
i vastedisposal(Section11-6). The condensate pu :ps, taking sr.ction from ,
the deaerator, pump' the degassed vater th cugh the mixed bed deuineralizer I
vhere ionic impurities and corrosion products are removed. An in-line radiation monitor is installed between the deaerator and the demineralizer.
The purified vater flows through the filter to the suction of the super-critical coolant pumps.
- _ . - . - - , - _ . . - . . . - - - . .~. . - _. - -- - -_ . . . - _ - . . .-.. ..
II ht 16 Deserator 4
A deaerator separates and removes dissolveh and entrained gases from the loop coolant and provides coolant storage and net positive suction head
(!IPSH) for the condensate purps. The deaerator is a vertical cylindrical tank, partially filled with Raschig v ring packing. Coolant enters through a spray nozzle at the top and flows downward through the packing. A liquid level is maintained in the bottom of the tank, and gases are removei from the space above this level and below the packing. The unit is velded except for a f3anged-top head closure and spray nozzle connection. All wetted surfaces, including Raschig rings, are austenitic stainless steel.
Condensate Pumps Two condensate pumps circulate coolant through the demineralizer to the loop pump suction. The condensate pu=ps are located below the deaerator.
The pumps are centrifugal, canned-motor units arranged to operate in series. The piping configuration also permits each pu=p to operate alone.
Both condensate pu=ps are required if both loop pump and standby pump are operating. The pumps are designed to produce normal system flow rate against the pressure determined by head tank level. All pu=p parts in contact with the coolant are fabricated of austenitic stainless steel or equivalent corrosion-resistant material.
Radiation Monitor An in-line radiation monitor is 1ccated downstream of- the condensate pumps for continuous measurement of the supercritical loop radiation level.
Local shielding is provided as necessary.
II-4: 17 D mineralizer
! .ushable, mixed-bed d mineralizer removes ionic impurities and corrosion e acts from the loop coolant stream. A hydrogen-form cation resin and a hydrogen-form anion resin are charged into the vessel. A retention screen on both sides of the resin bed prevents the loss of resin particles to the outlet line. The resin can be removed through a resin flush line above the retention screen. A screen at the inlet nozzle prevents resin from entering this line during backflush operations. The vessel is refilled with fresh resin through a fill Idne which can also be used for the insertion of resin sample probes.
The demineralizer vessel and internals are made of austenitic stainless steel with all joints and connections welded, b eal radiation shielding is provided for the domineralizer. The supercritical loop demineralizer is located near the reactor plant demineralizers to permit use of the existing resin handling lines and equipment. The velve located behind the shielding has an extension handle to permit operation during resin sampling or replacement, Filter A cartridge-type filter removes resin fines which may have passed through the deineralizer retention screen frcra the loop coolant. The cottor filter cartridge may be removed from the filter container and replaced if it-becomes fouled. The filter container is constructed of 304 or 316 I austenitic stainless steel. beal radiation shielding is provided for i
t.he unit.
[
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1 l
l
_ _ _ __ _ _ _ _ _ . . . . . _ . _ . . ._ . _ _ _ . - _ . _ _ . _ _ ,-- .~ _ ._ _ _ _ _ _ . - _ _ - _ _ _ _ . _ _ . . - _ _ _
II ki 18 4.6 Specimen Holders Three specimen holders are provided to permit insertion of corrosion test specimens in the cooh nt flow stream. One holder is located devn-stream of the heater in the inlet leg of ihe loop and the other two on either side of the interchanger in the outlet leg. Each holder consists of a coupon retainer assembly which fits snugly into a straight pipe section. Sample coupons slide into grooves in the retainer ard are held The retainer may be withdrawn to in place by spring-loaded set screws.
allow observation of specimens without removing them. A high pressure coupling is used at one end of the holder for removal of the retainer from the pipe. All parts of the specimen holder are fabricated of austenitic stainless steel.
k.7 Accumulator An accumulator is provided to reduce pressure pulsations in the coolant loop. A rubber diaphragm separates the loop coolant from the pressurizirg gas. The accumulator is a cylindrical carbon steel tank whose interior is lined with Lithcote LC-53 as a protective coating.
n k.8 Piping and Valves All supercritical loop cochnt piping is austenitic stait.less steel.
Service piping for component cooling water.and air is carbon steel or copper. Piping ,)oints in the main coolant stream are velded except for remote disconnect cot.plings at the pressi e tube and specimen holders to facilitate removal for inspection or maintenance.
11 4 : 19 Manually cperated s*,op valves are provided to chanEe flew cire .it ry, t o permit ve . ting, filling and draining of eceponents, and to permit isolatien cf cer's . coeper.ents f;r maint enance. Extension stems are provided for those valves not readily accessible to the operater. Check n1ves are provided to prever. reverse flov 'nithin the loep and leaksge from or into external plant auxiliary systems.
Remotely operated stop valves are used to isolate locp eq dpmen' t ct in use, bypass various port ions of the loop, isolate connectione % of.her plant auxiliary systems and vent or irain ermpenents not accessib!.e durir.g locp operation er detontaminatien. All valves containird, radica:tive fluids are provided vinh valve stem leakoffs or ban sea's to trair.* ai-essentiany zero leakaBe to atmosphere. Instrt. ment valves are wapt frcm inis requirement.
All valves in cont.a:t with the loop ccclar+., are austenitic stsiG.ess steel. Service valves for ecoling wa*.er or air are trass er sn equivaler' material. Supercritical loep piping, valves and eq11pment. which cpe? ate at elevated temperawre are covered with t hermal it.sCa .icr, where re essary, to minimize heat lesses. II.sulatien is provided on lines connecti g the interchanger to the pressure Woe and cn the line from inter: hanger 4 :
hign-pressure coc3 er . In addition, tue 1 ale' 11".e to + he emergency -ctnief.ze -
is insulated.
4 N
4 k..i .. .i . _ _ _ _ _ _ _ _ -.1 _.____ . _ _ _
- * ' ~ ~ -. -
II-5: 1 5 AUXILIARY SYSTDS n the following functions:
Auxiliary systems are provided to ne a) Component cooling b) Shutdown cooling c) Coolant makeup d) Safety injection e) Pressure relief f) Sampling g) Decontamination h) Reactor head nozzle cooling 51 component cooling Flov from the component cooling system of the Saxton reactor is used to high cool the following pieces of equipment in the supercritical loop:
pressure cooler, low pressure cooler, sample coolers, recombiner condense 2, and vacuum pump seal vater cooler. The component cooling water flw is adjusted by temperature controllers to maintain the desired crpercritical coolant temperaturts at the cooler outlets. The te=perature c at ollers, the set point temperatures and the component cooling water d"sien flow rates are:
Temperature Set Point Component Cooling Tempesture Water Design Flow Rates Cooler Controllers TRC-X11 180 F 27,800lb/hr High pressure cooler TRC-X1B 130 F 22,400 lb/hr Lov pressure cooler 130'F 1,000lb/hr Sample coolers (Not controlled)
TC-X21 105 F 2,500 lb/hr Seal water cooler and recombiner condenser
II-5: 2 Cooling vater flows to the vacuum pump seal water cooler and recombiner condenser in series. The component cooling water pressuro relief valve, .
PSV-6, is set to relieve at 150 psig.
52 Shutdown Cooling Shutdown cooling utilizes the hi6h pressure and low pressure coolers described in Section II k, Supercritical Coo h nt System. The circulation is supplied by the condensate pumps. In addition, emergency cooling can be effected by using the emergency condenser described in Section 11-5 4, Safety Injection System.
53 Coolant Makeup The supercritical loop is filled by gravity with vater supplied from the head tank. The water enters the loop piping at the suction of the super-critica.1 coolant pumps. During fillings the standby loop pump is operated ,
to circulate water through the loop. The vent line from the pressure tube outlet, to the collection header is open to instrument LI-X4 for level irdication.
The head tank provides NPSE for the loop pumps during operation of the supercritical loop. The tank is a vertical cylindrical vessel fabricated of stainless steel and is provided with an overflow. It is designed for a pressure of 65 psig or full vacuum at 332 F.
54 Safety Injection The Safety Injection System contains the following equipment:
a) Coolant reservoir b) Reservoir gas cylirAer
II-5: 3 c) Gas compressor d) Rnergency condenser i During emergency conditions, i.e., loss of flow or loss of coolant, the supply of pressurized water held in the coolant reservoir is discharged auto:ntically to the accumulator connection of the loop fonowing loss of flow or to the pressure tube outlet line upon a loss of coolant upstreer. of the pressure tube. Driving pressure for this water injecticn is furnished by the gas cylinder. Once the pressure tube is filled with water, fuel cooling is accomplished by free convection, using the emer-gency concenser as a heat sink. After safety injection, the three-vay valve at the outlet of the coolant reservoir closes the coolant reservoir port to prevent discharge of nitrogen into the loop. Simultaneously, the tiervice vater inlet port is opened thus anoving service water to flov into the loop through the safety injection line. This flav insures that the pressure tube vill have an acequate supply of water during coolin6 vith the emergency condenser. Steam produced by residual heat from -the fuel assembly flows up the outlet pipe to the emergency condenser.
The condensate returns to the pressure tube inlet by gravity flov. This process continues until the fuel assembly can be safely removed from the reactor.
Coolant Reservoir The coolant reservoir holds a supply of coolant under pressure for injec-tion into the loop in case of loss-of-coolant
- loss-of-flow accidents.
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The reservoir is a vertical cylinder constructed of carbon steel. All l
joints and connections are velded. The reservoir-is designed for 5000 l
peig at 200 F and meets the ASME Boiler and Pressure Vessel Code,Section VIII. Its capacity is 25 gallons. The valves for inititting injection aie' located to minimize ~ delay time for injection-of coolant into the loop.
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II-5: 4 Beservoir Gas Cylinder The reservoir gas cylinder holds the pressurized nitrogen that drives the coolant reservoir water into the loop. The cylinder is constructed of carbon steel with all joints velded. It is designed for 5000 pois and meets ASME Boiler and Pressure Vessel Code,Section VIII.
Gas Cocrpressor
\y-A gas con: pressor is provided to charge the reservoir gas cylinder and mintain its pressure at a specified value. The gas compressor is desi6ned for a discharge pressure of 5000 poig and a suction pressure of between 200 and 2500 pois. Nitrogen is supplied to the compressor inlet from a hiSh pressure commercial container. The compressor is driven by compressed air supplied by the loop air compressor.
Emergency Condenser The esnersency condenser continues fuel cool.ing during an extended loss-of-l coolant or loss-of-flow accident. In addition, this condenser removes residur.1 heat from the fuel during decontamination or during draining of l
! the lcop for mintenance. The unit consists of a pipe coil mounted in a vertical drum. Heat is removed by' permitting the water in the drum to boil. An intermittent flow of makeup water balances losses due to vapori-zation. The emergency condenser is located above the pressure tube to pro-vide sufficient thermal circulation head and to minimize piping flow resistance.
The unit is fabricated of austenitic stainless steel using all-velded construction. An overflow and vacuum break are provided. The condenser is designed for 15 psig shell and 4h00 psig at 1000 F tube. The unit is designed to the ASME Boiler and Pressure Vessel Code,Section VIII, Nuclear Case 1273N.
. s II-5: 5 55 Pressure Relief General Description The supercritical loop is protected from overpressure by relief valves on:
i a) outlet line from the pressure tube, b) discharge side of the loop pump and standby pump, c) discharge side of the gas compressor, d) demineralized water line supplying the coolant reservoir, and e) component cooling water line.
Two rupture discs are also supplied. One protects the low pressure cooler from overpressure in the inlet. A second protects the denerator from overpressure. An cutomatic valve is located between the pressure tube inlet and outlet lines to protect the intemhanger in the event of blockage of the pressure tube. Upon receiving an excessive positive pressure drop signal, the valve automatically opens to pemit the flow to bypass the pressure tube. This bypass is also used to flush out the pressure tube connectors before they are opened.
Pressure Reldef Valves The pressure relief valves are self-actuated, totally enclosed, spring-loaded valves.
The valves on the ' outlet line- from the pressure tube, PSV-1 and PSV-2, discharge to the storage well below normal vater level. Each valve is des $ gned to relieve one-half of the maximum combined flow of the loop pump and the standby pump. The set pressures are 4000 and 4400 psig respectively.
The valve on the discharge side of the loop pump, PSV-3, relieves to the suction side of the pump. The set pressure is 5000 psig.
II-51 6 The valve on the discharge side of the gas compressor, PSV-4, relieves to the atmosphere. This valve is designed to pass 20 times the nomiral dis-charge rate from the gas compressor at a set pressure of 5000 psig.
The valve on the cemineralized water line, PSV-5, discharres to the atmosphere. The set pressure is 150 pais.
For PSV-6, see paragraph II-5 1.
Rupture Discs The rupture disc on the inlet line to the low pressure cooler relieves to the line from the deaerator to the discharge tank. It is set to relieve at 1000 poig. The rupture disc from the deaerator relieves to the discharge tank and is set to relieve at 50 psig.
56 sampling Geneml Description The Sampling System is shown on Figure II-7 Three types of samples are taken from the supercritical loop: ,
a) periodic gas samples b) continuous crud samples
! c) periodic liquid samples Gas samples are taken by directing the discharge of the vacuum pump in the radioactive vaste disposal system (Section II-6) through a gas drier into a gas sample holder.
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II-5: 7 Crud samples can be taken continuously from three points in the loop; irnediately upstream of corrosion specimen holders 1 and 2 and downstream of corrosion specimen holder 3 Each sample stream flows through a sample cooler, then through a pressure-reducing valve into a mixed-bed samp1r ion e.xchanger. Impurities in the stream are retained in the ion-exchange resin. The sample stream is returned to the loop at the deaerator.
Periodic liquid samples are also taken upstream and downstream of the demineralizers. Since these are cold, low pressure streams, they are routed to the plant sampling system, outside the vapor container, where norral sampling techniques may be used.
Gas Sample Drier A drier is located immediately ahead of the gas sample holder to remove water vapor from the sample stream. The unit consists of a vessel filled with a chemical dessicant.
Gas Samule Holder The gas sample holder stores the hydrogen, oxygen, and fission gas samples periodienlly taken from the off-gas stream. The unit is a cylindrical stainleas steel vessel of welded construction. It is desi6aed for pressures from full vacuum to 25 psig. le shutoff valve and disconnect coupling are furnished as part of the unit,.
Sample Coolers Three sample coolers are provided to reduce the sample stream temperature sufficiently to permit letdown without flashing. Each cooler is a double-pipe coil unit. The inner tube, which contains the sample stream, is made
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II-5: 8 of gold-plated stainless steel. Component cooling vater flows in the annul'as between the inner tube and a copper outer tube. The design shell pressure is 150 peig and design tube pressure is 4500 peig at 1000 F. The coolers are designed according to the 16ME Poiler and Pressure Vessel Code,Section VIII, Nuclear Case 1273N.
Sample Ion Exchangers Three sample ion exchangers separate crud from the loop coolant samples.
Each unit consists of a section of austenitic stainless steel pipe filled with mixed anion-cation exchange resin. Both upper and lower heads are removable to pemit post-operational analysis of the resin. Shutoff valves, disconnect couplings and external lead shielding are furnished as part of the unit. Each ion exchanger is designed to ASME Boiler and Pressure Vessel Code,Section VIII, Nuclear Case 1273N.
57 Decontamination A decontamination syste.n is provided for supercritical loop decontaminn-tion and consists of a feed tank used for mixing and storing of decon-tamination solutions. The solutions flow into the supercritical coolant system at the loop pump suction. The tank is elevated to meet pump NPSH requirements. The tank is a vertical stainless steel vessel which is open to the atmosphere and provided with a removable cover.
5.8 Reactor Head Nozzle Cooling System The reactor head penetration nozzle for the supercritical pressure tube is designed for a temperature of 650 F. In order to limit metal temperature to this value when supercritical loop coolant at 950-looooF is flowing through the pressure tube, the nozzle and adjacent vessel head a"ea must h
I II-5: 9 l
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be cooled. This function is accomplished by bleeding 500 lb/hr of .
reactor coolant throu6h the annulus between the pressure tube and the pene '
tration no.:zle. The bleed stream flows through a cooling coil which is innereed in the water in the store 6e well and then passes throu6h a pressure-reducing valve to the Sarton reactor purification system downstream of the pressu.re letdown valve. Bleed flow rate is indicated on the loop control board and an alam is activated by hi h S nozzle temperature.
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II-6: 1
- 6. RADI0 ACTIVE WASTE DISPOSAL Liquid vastes from the supercritical loop are drained by a line downstream of the demineralizers to the Saxton Reactor Radioactive Waste Disposal (
System. Gaseous vastes from the supercritical loop are vented from the
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deaemtor to the Saxton Reactor Radioactive Waste Disposal System.
The supercritical loop gaseous vaste disposal system consists of a vacuum pu:::p and its seal vater system and a catalytic recombiner package.
The vacuum pump draws the gases from the deaerator and pumps them to the recombiner package. The residue of gases re: mining after recombination of the radiolytic gases flows to the Sarton Reactor Radioactive Waste Disposal System. Diluent steam from the recombiner is condensed and flows back to the vacuum pump seal vater reservoir.
Vacuum Pump The vacuum pump removes a mixture of non-condensable gases and steam from the deserator and maintains the required deaerator operatin6 pressure.
This pump is a single-stage, water-scaled type. The vacuum pump is cooled by the sealing vater which v.irculates through a heat exchancer. The pumped vapor which condenses in the pump along with the water condensed from the recombiner is mixed with the seal vater in a reservoir downstream of the vacuum pump. As the water level in the reservoir rises above the required seal water level, a level control opens a drain to the deaerator restoring the proper water level. All pump parts in contact with the pumped fluid are bronze or cast iron. Closures and connections are either screwed, balted or flan 6ed with suitable Sasketc.
1
II-6: 2 Vacuum Pump Seal Water Reservoir The vacuum pump seal water reservoir receives the mixture of water, steam and non-condensable gases discharged by the vacuum pump and provides a volume for separation of the gas and liquid phases. In addition, the unit acts as a standpipe to maintain an adequate supply of seal vnter for the vacuum pump. An electrically heated auxiliary steam generator is connected to tM reservoir to provide diluent for the radiolytic gases flowing to the recombiner. The reservoir and steam generator are vertical sections of stainless steel pipe with all connections socket-velded.
Vacuum Pump Seal Water Cooler The vacuum pump seal water cooler removes the heat added to the seal water by the-pump and maintains the seal vater at a constant temperature as it enters the pump. The cooler is a double-pipe coil vith the seal water in the inner tube and cooling vater in the annulus. The inner tube is stain-less steel and the outer tube is copper.
Catalytic Recombiner The catalytic recombiner removes mdiolytic hydrogen and oxygen from the off-gas stream by recombining them into water vapor. Diluent steam from the auxiliary steam generator, almg with the water vapor produced in the recombiner, is condensed in the recombiner condenser and drains back into the vacuum pump seal water reservoir. The unit is designed to the ASME Boiler and Pressure Vessel Code,Section VIII, Nuclear Case 1270N.
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11 7: 1 7 INSTRUMDCATION AND CONTROL 4
71 Inlet Heat Content Control Heater Control, QC-X1 The heater control regulates pressure tube inlet temperature by varying beater output. This unit normally receives three input signals and a set-point signal from one of two sources. The first input signal is from the heater inlet temperature recorder, TRC-IlO. The second input signal is provided by the supercritical coolant flow controller, FRC-X1. The third input signal is provided by the heater power recorder, Q,RC-X3 The first set-point signal is provided by the hecter outlet temperature -
recorder-controller, TRC-X9 This signal is dependent on the difference between desired and actual heater ontlet conditions. A second set-point signal may also be provided by a manual dial setting on the controller.
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The instrument computes the required heater power from the temperature and i flow input signals. This result is compared with the actual electrical power supplied to the heater. If a differential exists, a control signal' is transmitted to a power controller which supplies a direct-current control voltage to the saturable reactor. The saturable reactor adjusts heater electrical supply to the required level.
In the event of a loss-of-flow or loss-of-coolant a.ccident, a signal from the inst $rument detecting the accident (see PRC-X4, FRC-X6, FRC-X1) to the heater control shuts off the heater. Heater shutoff signals are alno generated by instruments detecting excessive pressure tube differen-tial pressure (FO-X26, Ft'-X28) and high pressure tube outlet temperature TRC-X4).
- During experiments not requiring the heater, the heater control is used '
l to regulate pressure tube inlet conditions by operating the interchanger bypass valve. In this case, input to the control is the error signal from the heater , outlet temperature (TRC-X9).
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II-7 2 Heater Power, QRC-X3 A thermal converter on the saturable reactor Eenerates a signal propor-tional to heater power. This signal is sent to the heater control, QC-X1, and is recorded on the loop control board.
Heater Inlet Temperature, TRC-X10 A temperature detector on the heater inlet sends a temperature si6nal to the heater controller, QC-X1, and to a reconier on the loop control board.
Heater Outlet Temperature, TRC-X9 A temperature reconier-controller on the heater outlet provides a set- ,
point signal for the heater control, QC-X1. The set-point signa? is a function of the desired temperature and the difference between it and the actual tempemture.
The unit also provides an alternate control signal for the interchanger bypass valve when experimental conditions call for the use of this valve.
Tne heater outlet temperature is recorded on the loop control board.
l 72 Flow Control Loop Flow Control, FRC-X1, FA-X2, FA-X7 A flow recorder-controller on the loop pump discharge line maintains the required flow during normal loop operation and initiates protective measures
! in the event of a loss-of-flow accident.
II-7: 3 During normal operation of the supercritical loop, the instrument receives and transmits the following signals: f
- 1. A mnual input signal which sets the nominal flow rate for the pt.rticular experiment.
- 2. An input signal from the fuel assembly outlet temperature recorder-controller, TBC-Xh, which modifies the set point in accordance with temperature variations.
3 An input signal from the loop flow detector. This signal is compared with the set point value in the controller.
- 4. An output signal to the loop pu=p bypass valve operator, which adjusts the valve position to maintain the correct flow.
5 An output sigral to the heater control, QC-X1. This flow signal is used in computing the actual heat input of the heater.
- 6. An output signal to a flow recorder mounted on the loop control board.
During a partial loss-of-flow accident (defined as reduction in flow to betveen 80% and 50% of set point value), the instrument receives and trans-mits the following signals:
- 1. A mnual input signal which sets the nominal flow rate for the particular experient. The set points which define the accident are autcentically adjusted to this signal as a "100% flev" reference.
- 2. An input signal from the loop flow detector. This signal is compared with the limit set points to define the accident.
3 An output sigral to the heater control, QC-X1, to shut off the heater.
- 4. An eutput signal to the standby pump motor starter to start the pump if it is not already operating.
5 An output signal to activate a partial loss-of-flow alarm on the loop control board.
- 6. An output signal to a flow recorder mounted on the loop control board.
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II-7: k During a total loss-of-flow accident (defined as reduction in flow to below 50% of set point) the instrument receives and transmits the same sigrils as during a partial loss-of-flow vith the following additions:
- 1. An output signal to scram the reactor and activate an alarm on the reactor scram panel. If the flow is brought above the 50% limit before a preset dehy time elapses, the scram signal is blocked.
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- 2. An output signal T,o the coohnt reservoir isolation valve operator to open the valve.
3 An output signal to the loop pressure control valve, PRC-X6V, which suppresses its normal control function. Nration of the pressure control valve is then assumed by the flu. ' _atroller, which maintains a preset constant flow. The loop pump bypass valve is closed and receives no control signal during this opemtion. The flow controller is reset manually.
Sample Flow, FRC-X15, FRC-X16, FRC-n7 Flow recorder-controllers in each sample path regulate the letdown valve to maintain a constant sample flow. The flow is recorded on the loop-control board. The records are used in making quantitative studies of crud level in the sample streams.
Peactor Head Nozzle Bleed Flow, FIC-X9 A flow controller on the bleed line from the reacter regulates a control valve to maintain a constant cooling flow through the reactor head nozzle which supports the pressure tube. The flow-rate is indicated on the control board.
II-7: 5 73 1.oop Pressure Control, FRC-X6, PA-X3, PA-X7 A pressure recorder-controller on the pressure tube inlet reEulates the control valve betveen the high pressure and low pressure coolers to cain-tain a constant inlet pressure.
1 This instrument also provides a reactor scrum si6rcl in the event of a }
loss-of-coolant accident. An alarm on the loop control board is actuated to warn of high pressure or low pressure conditions, and a second alarm is activated by the loss-of-coolant scram signal. In addition, an output signal is sent to the heater control, QC-X1, to shut off the heater upon loss of pressure. The pressure is recorded on the loop control board.
The normal pressure control function of this instrument is suppressed during loss-of-coohnt or loss-of-flow emergencies by either of two over-ride si6tals. If an accident calls for coolant injection at the pressure tube inlet (loss of flow), the loop flow controller, FBC-X1, assumes control of the valve and regulates its position to maintain a constant flow. When coolant is to be injected into the pressure tube outlet, the differential pressure controller, PRC-X4, closes the pressure control valve so that all injection flow passes throu6h the pressure tube. The pressure controller 1s reset manually.
l 74 Supercritical Loop Protection System Pressure Tube Differential Pressure, PRC-I4, PA-X5 A differential pressure recorder-controller across the pressure tube controls cochnt injection and provides a reactor scram signal in the event ,
of a losc-of-coolant accident. Under normal operating conditions, pressure drop across the tube is positive (i.e., inlet pressure exceeds outlet pressure). However, a pipe break between the loop pump and the pressure tube inlet vill result in a rapid flow reversal and a concurrent pressure l
t
II-7: 6 drop reversal. Upon detecting this change, the contrdler opens the coolant injectico valve to the prescure tube outlet (FIC-X3), closes the loop pressure control valve (PRC-X6), sends a heater shutoff signal to the heater control (QC-X1), and actuates an alarm on the loop control board. The dif-ferential pressure signal is also recorded on the loop control board.
Pressure Tube Outlet Pressare, PC-X14, PA-X12 A pressure switch at the outlet of the pressure tut actuates an alarm on the loop control board when the pressure falls below a set value. The alarm provides an independent verification of the occurrence of a loss-of-coolant accident or hi6h or low pressure.
Pressure Tube Differential Pressure, PC-X26, PC-X28, PA-X29 Two differential pressure switches across the pressure tube protect the interchanger tube against excessive differential pressure if flow throu6h the pressure tube is blocked. The first switch is set below the tube extermi design pressure and the second is set at that pressure. When the set point of the first switch is reached, the heater is shut off. If the differential pressure increases to the set point of the second switch, the pressure tube bypass valve is opened and an abrm on the loop control board is actuated-Pressure Tune Outlet Temperat ure, TRC-Xh, TA-X19 A temperature recorder-controller measures the temperature at the pressure tube outlet and supplies a set-point signal to the loop flow controller, FFC-X1. The temperature is recorded on the loop control board. An alara in the control room is actuated and the h2ater is turned off if the tempera-ture approaches its maximum permissible value.
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4 0 II-7: 7 Injection Line Temperature, TR-X2-10 A temperature detector is located on the injection line connected to the pressure tube outlet piping. Thic temperature is recorded by the multi-point recorder on the loop control bc rd. In addition to injection tem-1eratare, this detector monitors emergency condenser inlet temperature or loop safety valve inlet temperature when either of these items is in operation.
Safety Injection Flow, FIC E An indicator-controller en th
- safety injection line regulates a control valve te maintain a constant 1 jection rate. The controller is normal'.y inoperative and must be activat yd by a less-of-coolant signal from the pressure tube differential pressure controller, PRC-X4. Once activated, the injection flow controller continues in operation until manually shut off. The injection flow rate into the pressure tube is indicated on the loop control board.
The following scram signals are provided by the supercritical loop
! instrumentation:
Instrument Reason l PRC-X6 Loss of-coolant PRC"X4 Loss of coolant FRC-X1 Loss of flow The lines for these three scram signals are connected ir parallel into the -
Saxton. reactor scram circuitry and in no vay affect the functioning of any of the other Saxton reactor scram signals. These ceram signal connections need to be opere. tic:al only if a fue.ed pressure tube is installed in the reactor.
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II-71 8 ,
Coolant Reservoir Level, LIC.X6, IA-X7 A level-indientor controller positions a three-vay valve to a'dmit de-minemlized vster instead of coolant reservoir vnter to the loop when the coolant reservoir is exhausted. The valve simultaneously c)oses off the reservoir to prevent injection of the precrurizing gas into the loop. An alarm on the loop control board is actuated by a low-level sigwti. The reservoir level is continuously indicated on the loop control board to provide additim1 not. ice of leakage from the vessel.
Dnergenc3 * *nser Level, IE-X2_
A level controller on the emergency condenser operates a mrtkeup valve to repince vaporization '.osses and keep the condenser coil submerged at all times.
75 Procens Jic+.rumentatier.
a) Temperature i
Int.erchanger T,etnperaturen TR-X1-13,14,15, X2 4 Temperature detectors are located on the four lines entering and leaving the interchanger. These temperatures are recorded by a multipoint recorder on the loop control b0ard. The recorded tempem-l tures permit esaluation of interchanger perfomance.
Pressure Tube Inlet Temperature, TR-X3 The temperature of the coolant entering the pressure tube is recorded on the loop control board. This temperature is used as a check on the pressure tube inlet temperature control and for estAmating pressure tube heat losses.
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1 11-71 9 geh Prennure Cooler Outlet Temperature, TRC-X11, TA-X20 A temperature recorder-controller on the outlet of the high pressure cooler controls component cooling vater flow to the cooler to maintain a constant outlet temperature. The temperature is a 50 recorded on the loop control board. An alarm to actuated if the tecerature of the 1eop coolant at the outlet of the cooler is too high.
Condencate pump Dischnrge Temperature, TF-X2-6, TA X12 A temperature detector io located on the condensate pump discharge line. The temperature is recorded by the multipoint recorder on the loop control board. An alarm is actuated if the temperature exceeds the nnximum allowable denineralizer inlet temperature.
Fu,el Annembly remperatures, TR-X1 - 1 to 12 Coolant temperatures at various points within the pressure tube are monitored continually by a multipoint temperature recorder. Up to twelve temperatures may be measured. The recorder is located on the loop control board. The recorder vill alnrm upon exceccive temperature l readings at the coolant channel outlets. The reconier is cet to record coolant channel inlet and outlet temperatures alternately to minimize l
the time between the reading of outlet temperatures. Failure of a themocot.ple vill cause an off-scale reading and alarm.
Component cooling Water Temperatures, TR-X2-5, 7 Temperature detectors are located on the component cooling vater supply (TR-X2-5) and return (TR-X2-7) lines. These temperatures are recorded by the multipoint recorder on the loop control board.
II-71 10 Lov pr essure Cooler Outlet Temperts'.ure, TRC-X18 4
A temperature recorder-controller on the outlet of the low pressure cooler controla component cooling water flow to the cooler to main-tain a constant outlet temperature. The temperature is recorded on the loop control board.
Ehrety Valve Discharge Temperature, TB-XF-3, 9 Temperature detectors are located on the discharge linen of pressure safety valves, p3V-1 and FSV-2. to indicate leakaSe through the valves or the lifting of the valves. These tec:peratures are recorded by a multipoint recorder on the control board.
Beactor Head Nozzle Bleed Temperature, TR-X2-11,12 Tewperature detectors are located at the inlet and the outlet of the cooling coil which cools the bleed from the reactor. TR-X2-11 gives an indication of the effectivenens of the system in cooling the nozzle. TP-X2-12 gives an indication of a temperature which would cause flaching acroco the preocure letdown valve. The temperatures are recorded by a multipoint recorder on the control board.
o Vacuum Pump Seal hter Temperature, TR-X2-13, lhj,_TC-X21 TR-X2.14 is located on the seal water reservoir. TR-X2-13 in located on the seal vater line to the vacuum pump, and permito detection of excessively high seal vnter temperature. These temperatures are recorded by a multipoint recorder on the loop control board. .TC-X21 is a locally mounted tempemture controller on the seal vater line to the vacuum pump and controls the component cooling vater supply to the vacuum pump seal vater cooler and the recombiner condenser.
II-7 11 Hecombiner Condencer Drain Tempersture, TR-X2-13 A temperature detector is located on the recombiner condenser drain to the vacuum pump seal vnter reservoir. This temperature permits evaluation of the operation of the recombiner condenser. The tem-perature is recorded by a multipoint recorder on the control board.
Ihmple Cooler Discharce Temperature, TR-X1-lh,15,16 A temperature detector on the process steam outlet of each sample cooler monitors the sample stream temperature entering canh sample ion exchanger. The temperatu2 es are recorded by a multipoit4t recorder on the control board.
b) Pressure Accumulator Pressure, PR-X2 The pressure in the accumulator gas space is recorded on the loop cotstrol board. This reading, in conjunction with PR-X20, permits an evaluation of accumulator effectiveness. The accumulator pressure range is 2000 to 5000 pi vith a + 50 psi anuracy.
Compressor Discharge Pressure, PC-X10,- PA-X13 A local pressure controller on the gas header supplying the gas cylinder operates the compressor to maintain gas cylinder pressure above a preret value. The instrument provides an on-off signal to the compressor motor starter and a low pressure signal to an alarm on the loop control board.
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Il-7 12 Insp Pump Dicchnrge Precoure, PR-X20 A pressure ce+,ector on the loop pump discharge piping sends a si6nal to a recorder on the loop control bourd. This reading and the accumulator pressure reading PR-X2 are recorded on the name chart.
A comparicon of the two traces given an indication of the accumulator pultation-damping effectiveness.
Gas 11eader );easure, PI-X11 A local pressure detector on the gas header monitors Bas precsure during coolant reservoir filling operations and provides a check on the compressor control, PC-X10, during testo.
Gas Sample Holder Pressure, pI-X21 A pressure indicator on the inlet 1.ine to the gas sample holder provides a reading of pressure in the vessel on the loop control board. This readinS is used to detemine when the gas sample holder is fully charged.
Deaerntor Pressure, PRC-X22, PA-X8 ,
A pressure recorder-control.ler on the deaerator prevents excessive '
pressure on the vacuum pump by cloning the pump inlet valve if denerator precoure exceeds a preset value. An alarm on the loop control board is actuated by a high pressure signal. The deaerator precsure is continuously recorded on the loop control board.
himmmiinim ima mu n as a suii iii du
11-72 13 Interchanger Differential Precsure, PI-X23, PA-X26 A differential pressure detector on the interchanger provides a con.
tinuoun reading on the loop control board of the difference between cold side inlet pressure and hot-side outlet pressure. This pressure difference reading is used in predicting and evaluating interchanger performance. A pressure alarm is actuated when the differential pressure approaches the external design pressure of the inner tube of the interchan6er.
Itigh Precoure Cooler Outlet Pressure, PI-X25 A local pressure indicator is located on the outlet of the high pres-sure cooler. This instrument is used during loop shakedove runs as a check on the accuracy and response of the loop pressure control, PRC.X6.
Condensate Pump Discharge Pressure, PI-X24 A. pressure indicator on the condensate pump discharge line provides a continuous reading on the loop control board of pump discharge pressure.
Filter Differential Pressure, PC-X30, PA-X31 A differential pressure switch across the filter monitors the per-formance of the unit. The switch operateo a signal light on the loop control board when pressure drop reaches a value which characterizes a fouled filter element.
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II-71 14 t
c) Flav l
Demineralized Water Flow, FB-X8 A flow detector is located in the demineralized water line to the hmd tant and the emergency condenser. The flow to recorded on the control boc.rd and infonts the operat or of the frequency of head tank filline, vater r.nkeup requiremento of the loop, leakage of water int:
the emergency condenacrf and emergency condenser cooling voter require-ments during operution.
Loop Punt and Standby pump 01nnd Leakoff Flow, FI-X10 A flow detector is located in the gland leakoff linen of the loop i pump and ctandby pump to measure leakage through the pump packin6 I The reading is indicated on the control board.
Loop Flov7 TR-Xk The loop flow downstream of the heater is reconied on the loop control Doard. This instrument in provided for experimental purposes and utilizes a pipe elbow as the sensing element.
d) Level Hoad Tank Level, LIO.X1 l
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l A level indicator-controller operates a makeup valve to maintain the vnter inventory in the head tank above a preset level. The instru-ment provides a continuous level indication on the loop control board.
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II-7: 15 gop Vent Line Level, ll-Xia
/s local level indicator in the loop vent line is used while filling the loop. The appeamnce of a water level at this instrument is an indication that the loop in fall.
l l Dmera*.or icvel, LIC-X3 A level indicator-cent roller regulates a control valve to cnintain a constant liquid level in the deaerator. The valve throttleo the condensate pamp discharge to entch the inflow to the deaerator. A continuouc level indication la provided on the loop control board.
Denerator Level, If ~XB. IA-X9 l
A probe-type level controll.er, mounted in the lower plenu:n of the deaerator, prevents vater overflow to the vacuum pump by closing the l pump inlet valve if liquid level exceeds a fixed value. The instru-ment simultaneously actuates an alarm on the loop control board.
l Vacuum Pump Seal Water Reservoir Level, LIC-X10 l
I A level indicator-controller regulates a drain vulve to maintain the vnter level in the vacuum pump seal water reservoir between high and low limits. The water level is indicated on the control board.
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II-7: 36 l
1 e) Interlockc l
Precoure Tube Isolntion and Loop Bypaso Yalves, llc-X2h, !!C-X25, llc-X26 l
The pressure tube isolation and loop bypace valve controls are inter- i l locked to prevent accidental isolation of the main process line. The interlock does not permit the isolation valven,110-X2h and HC-X26, to be cloced until the by}mec valve, IIC-X25, is open. j
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Bpecimen 11 older Bypaca and Sample Valves, llc-X15, IIC-X21J 11C-X16,110.X"2 The bypnos valves and sample valvoo for specimen holders 1 and 2 are interlocked to prevent backflow throughthe specimen holders. The i interlock does not pwmit a bypass valve, HC-X21 or IIC-X22, to be opened until the corresponding sample valve, IIC-X15 or !!C-X16, is closed.
f l
76 Radiation Monitors l
Condennate Pump Outlet Stream Radiation Level, RIC-X1, RA-X2 A radiation monitor in the line downstream of the condensate pumps sends a cignal to an indicator on the loop control board. This instrument also l actuaten an alarm on the loop control board upon detecting a high radiation level. The indication is a messure of the deaerator efficiency and of the
- demineralizer inlet conditions. This monitor warns of excessive leakage from the fuel elements by alarming on high radiation 2evel. The alarm is audible in both the control room and in the containment vessel.
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8 11-81 1
- 8. V/d1:R TRFATME!TI The supercritical loop is filled with demineralized vnter fra:n the i Saxton plant supply. No corrosion inhtbitore or other chemical additives cre uned. Since the loop contains a full-flow demineralizer and a
+
' deserntor, it is relatively ince.asitive to rakeup vater specifications.
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11-9: 1 f 9 ELECTRICAL SYSTD4 The min 4h0 V power supply to the supercritical loop la independent of the Snxton Reactor Plant Blectrical Service System. The supercritical loop 440 V bus will supply power to all supercritical equipment and controls, except for tne standby pump and one condensate pu:cp, which vill be cupplied from a motor control center of the Reactor Plant Electrics 1 Service System.
Standby power taken from the Saxton reactor inverter is provided for a group of critical controls and instruments as listed belov. Figure II-8 shows the one-line electrical diagram for the supercritical system.
Instruments Fed from Saxton Inverter Annunciator FRC-X1Ta TRC-X4T FRC-X1Ca TRC-X4Ca FRC-X1Cb TEC-X4Cb FRC-X1Ce PRC-X6f FRC-X1Cd P30-X6V FRC-X1Aa LIC-Gra PRC-X4T LIC. 6Ca PRC-XhC PCV-28Va PRC-X4 pCV-28Vb Total Power Required 750 volt-amps l
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III-11 1 III. OPERATION
- 1. LOOP STARTUP Loop startup is defined as the sequence of operations which bring the supercriticel loop from cold shutdown to preC *termined operating conditions.
Prior to initiation of Saxton reactor heatup, the main coolant piping and equipment, coolant reservoir, safety injection lines, and head tank are filled with demineralized vater. The system is vented to atmosphere until vater level appears at LI-Xh. The cystem is deaerated by operating the vacuum p wp and the condensate pumps until the deacrator pressure reaches a conctant value. At the same time, the gas compressor is operated to fill the reservoir gas cylinder and precharge the accumulator. When these operations are completed, the loop pressure control is set for the desired pressure and the loop pump started. As soon as component cooling flow to the coolers is established, the loop is ready for heatup.
Using the heater control and loop flow control, the temperature of the loop coolant at the heater outlet is controlled to maintain the loop temperature above the reactor and thus aid in the heatup of the Saxton reactor system.
The temperature difference between the supere11tical loop and the reactor system is maintained at a fixed value to limit thermal stresses at the l
reactor vessel head penetration for the pressure tube. After the reactor system is at the normal operating temperature and pressure, power operation can be started. As the reactor is brought to power and power generation in the supercritical fuel assembly begins, the control settings are adjusted j
i to limit heatup of the loop to LOO *F every five minutes.
l As luop conditions approach the values specified for the test run, final trim adjustments are made, and the loop is placed under fo.11 automatic cont rol.
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7 III-1: 2 i
The supercritical loop it held at steady-state conditions ur.til the reactor has been brought to itr desired operating condition. As power Eencration in the supercritical fuel assembly begins, adjustments are i rude to t,he control settings to compensate for the additional heat i input. Once reactor conditions have been stab 131 ed, supercritical '
loop heatup in resumed, using the same stepwise procedure and nnximum heatup rute limitation as before. Ao conditions approach their speci-fied values, final trim adjustments are undo and the loop is placed under full automatic control.
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-III-2: 1
- 2. OPERATION AT N4ER 4
Normal operation includes steady-state experimental operation at super- ;
critical pressures and hot standby operation. Steady-state operation '
includes all transients imposed on the loop by nomal reactor plant :
load cranges.
2.1 Supercritical precoure Operation Since the capercritical fuel power level is directly dependent on reactor power and may not be separately controlled, the loop control system com-pensates for power level changes by varyin6 coolant riov and heater power.
During steady-state supercrit,1 cal operation, coolant pressure is held constant at or near a specified value by pressure control valve PRC-X6.
When test conditions are to be changed, a stepwise procedure is used to assure that no operating limitations vill be exceeded. The primary-control variable is the fuel element outlet temperature which directly controls flow and indirectly affects the heater control. Gas removal ,
equipment operates continuously during supercritical operation to maintain constant deaerator pressure. When corrosion specimens are undergoing teac, the specimen holder sample trains are also in continuous operation. .
Deminerali::er camples are taken on a regular achedule, which may be modified by results of the sample analysis. b I
The range of conditions over which the loop is permitted to operate is illustrated in Figure III-1, which represents the allovable range for a full-power fuel assembly and an assembly. generating 69 5% of full power.
2.2 Lot Standby If the reactor plant is at power, heat is generated in the supercritical
- loop fuel assembly. Thus, even though experimental operation of the t
III-2: 2 cupercritical loop ic tmporarily halted, the fuel necen.bly must utill be cooled. Re .inop condition required for thin operation is defined as a hot cte dby condition.
To achieve a hot ctandby condition, the heater is chut off and adjust-mento are :tade in preccure and flow control set pointo to bring loop temperature and preocure to approxirately 2h00 pnic and 530 F. Theoe conditions generally correspond to react or nor.'inal operating conditions and thun effectively reduce any precsure differential or heat transfer a:roco the precoure tube vall. The hot otandby pressure in cet as lov as lorsible and yet not co hv thut s*.y leer I rnst.!e fluctuations vould give rise to a false low preccure scru cignal and thus unnecen-sarily chut down the pinnt.
Ihring hot standby, onmpling linea are shut off, although periodic snapling of the demineralizer effluent and influent may continue.
Gac removal equiluent remains in operation, since radiolytic gas generation continues ao long as neutron and gar:mta energy is absorbed by the coolant in the pressurc tube. Because of the increased coolant density (due to its lover temperature), the amount of radiclytic gas formed will exceed the steady-state value and result in a greater, but not excessive, recambiner load.
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III-3: 1 l
3 LOOP S1UfDCfdN Loop shutdown is defined ac the sequence of operations which brings the l supercritical loop from steady-state operation or hot standby to cold shutdown fer mintenance or refueling. Any shutdovn of the reactor necessitates a concurrent supercritical loop shutdown.
Prior to the initiation of re'ictor plant shutdown, the- supercritical loop is brought to a hot standby condition. As reactor power is reduced, l
the flow control set point is adjusted downward to maintain a conotant flow rate throu6h the pressure tube. This constant flov is mintained during the reactor cooldown procedure. Since the heat removal capacity of the supercritical loop exceeds the residual hmt generation in the l supercritical fuel assembly, the loop coolant stream also removes some j heat from the reactor coolant. l i
I I
Daring the shutdown operation, deminerslized vsWr is automatically l
added to the head tank to compensate for the reduction in loop water volume as temperatures are reduced. Gas removal operations continue I until the loop is depressurized. Although campling is normally not required during shutdown, individual samples may be taken at the dis- ,
cretion of the opera +or.
After the loop is depressurized to near atmospheric, the loop pump is shut off and circulation continued by the condensate pumps alone.- By periodically stopping these pumps and observing pressure tube coolant temperature, the operator can determine if heat transfer across the pressure tube well is sufficient to remove supercritical fuel residual heat. When this condition is attained, the condensate pumps are stopped _
and mintenance operations can begin. -
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III 14: I h, hEFUELDIG MID MAD 1TE'IANCE 4.1 Fefuelinc 4
Supercritical loop refueling operations are entried out with the reactor head in place and the storage vell flooded to normal plant refueling level.
During refueling, the condensate pumps are stopped and the pressure tube is isolated. The en.ergency condenser is placed in service to remove residusi heat. Aftcr the pressure tube disconnects have been opened, i
the coergency condenser is no longer needed as cooling is provided by l
l nstural convection to the storage well vster.
l To effect isolation of the pressure tube, the-Grayloc disconnects i
between the pressure tube and the block valves are broken and the block i
valves closed. The block valves prevent the borated refueling vnter from entering the loop. The Graylocs must be broken before the valves I
are closed so that the pressure tube vill not become completely isolated.
The Snoseal joint on the pressure tube is then broken and the pressure tube and fuel assembly are removed as a unit and placed in a special storage rsck in the storage vell.
The rev pressure tube and fuel assembly, which has been filled with demin-ers11:ed water and capped off, may nov be inserted into the reactor. After insertion into the reactor, the Conoseal joint is connected. The Grayloc joint is then mride up and the block valves are opened to complete the installa-tion of the new pressure tube in the loop system. This procedure is followed to minimize the amount of borated refuelin6 vater that gets into the loop.
Wher the loop is closed up, it is then flushed by closing the deaerator level control valve (downstream of the demineralizer and filter), opening the drain valve to vaste disposal and operating the loop pump until at-
_ least one system volume has been discharged or until sampling indicatea a sufficiently lov boron' concentration. The pump draws vnter from the head tank during this operation.
Ecmoval of the fuel assembly without removal of the pressure tube follows essentially the same procedure except-that the Grayloc disconnects are not opened and the Conoseal is not broken.
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III ht 2 L.2 Cleanup and Decontamination 1
4 Loop cleanup and decontamination defines the sequence of operations neces-sary to reduce shutdown radiation levels due to loop coolant activity to below the levels for the main plant. The magnitude of the operations involved depends on the mechanical condition of the fuel assembly prior to shutdown. .
If no fuel element defects have occurred, the loop coolant activity will-be negligible. The activity will be due primarily to corrosion products, which are removed in the demineralizer during post-shutdown circulation.
For this case, coolant activity levels are not expected to exceed 10' microcuries/cc(pc/cc).
' If one or more fuel elements are defective, but no gross failures have occurred, the coolant activity will-be less than 5 jac/cc. Circulation through the demineralizer at a rate of at least 2 gpm for a period of four hours vill reduce the activity to less than 0.01 J2c/ce. During the circu-l lation process, demineralizer influent and effluent streams are periodically sampled ar.d a decontamination factor (DF) determined by taking the ratio of inlet to outlet activity. If the DF falls to unity (no reduction in activity by the dcmineralizer), the demineralizer is flushed and filled with fresh resin.
If a gross fuel element failure has occurred, coolant activity levels. are two to three orders of magnitude greater than for defective fuel elements.
Under these conditions, additional operations are required to reduce activityto0.01pc/ce.
The first stage of cleanup is circulation of loop coolant at a minimum of 2 gpm, with the deacrator and_de*eralizer in operation and the pressure tube by-passed. Demir. era 11rer samples are taken periodically to determine the decontaination factor. If the DF falls to unity, either the demineralizer has removed all the activity or it has become saturated.
III-k 3 At this time, the flow is temporarily stopped and a reuiu sample is taken and analyzed. If the sample shows the bed to be unsaturated, the circu.
lation phase is ended. If the bed is saturated, it trust be flusheri and refilled with fresh resin. Circulation then resumes until it can be conclusively established, using the above me;thods, that all ionic impurities have been removed.
Following the circulation phase, a radiation survey is made and radiation levela due to supercritini loop activity detemined. If these levels are below those due to main plant activity, the cleanup operation is completed. If the levels are still too hign, decontamination is required to remove deposited activity.
Loop decontamitation begins with the preparation of suitable decontanina- a tion solutions in the feed tank. Prior to filling the loop with solutior, the demineralizer is isolated by opening the bypass valve and closin6 the outlet stop valve, and the three specimen holder diversion valves are positioned to bypass the holders. Decontamination solution can be added to the loop in two vays; either by setting up drain and isolation valves a:, for flusring and operating the loop pump until slightly more than one a syatem volume has been discharged, or by draining the system and then refill.ing the Bravity flow from the feed tank.
When the loop is filled, the bypass around the loop pump and standby pump is opened, the pumps stopped and the two condensate pumps started. Circu- .
lation continues until chemical analysis of the solution indicates satis-factory decontamination. The solution is drained to vaste disposal and dru:raed for storage and shipment. Following circulation and drainage of the decontamination solution, the loop is flushed vith demineralized vater to remove any rcmaining decontamination solution.
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l III-4: h h.3 Demineralizer Resin Removal and Addition ,
Deminer'alizer resin replacement operations are performed during shutdown and are, for the most part, controlled remotely. 'Ihe first step in this ;
operation consists of hack-flushing to loosen and break up the resin bed, which beccces packed during normal operation. Demineralized vater is flushed through the filter by-rass line into the demineralizer outlet line, up throuCh the bed and out through a drain line to vaste disposal.
After this step is completed, the filter by-inss valve and stop valve dcvnstrerun of the filter are closed, the resin sluice valve opened and the cundensate pumps started to force the resin out to the spent resin storagt, tanks. Makeup water for the loop is provided from the head tank by gravity flow. When all resin has been flushed out of the demin-eralizer, the sluice valve is closed. The resin fill operation, which follows, is perfomed locally. First, a temporary fill line is connected to the demineralizer from a fresh resin supply. The fill valve is opened, using an extension stem passing through the local shielding, and I
a measured amount of resin added. Finally, the fill valve is closed, the connection removed and the fill line closure replaced. The us* is ready for further operation as soon as the outlet and inlet valves are opened.
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III 5: 1 5 D'IRGENCY OPERATION 51 Locs or_ Coolant Flow Loss of coolant flow results from a calfunction or shutdown of the loop pump due to a manual or automatic tripout, mechanical failure, excessive leakage through packing, or power failure. On the basis of required corrective action, two types - of loss-of-flov accidents have been defined:
a) partf ul loss of coolant flow is defined as a reduction in measured flow to less than 80%, but not less than 50%, of the loop flow control set point at the time of the accident.
b) Complete loss of cochnt flow is defined as a reduction in measured flow to less than 50% of the loop flow control set point at the time of the accident.
A partial loss of coolant flow condition vill result in automatic shutdown of the heater and startup of the standby pump.
A complete loss of coolant i' low vill result in reactor scram, an automatic injection of water from the coolant reservoir, and automatic operation of the loop pressure control vulve to maintain constant flow, in addition to the automatic actions initiated by a partial loss of flow.
52 Loss of Electrical Power Loss of electrical power to the supercritical loop recults in essentially the same autocatic actions as a complete loss of coolant flow. If all ,
power is lost, the situation is handled in a manner similar to the loss of flow with the standby pump inoperable. . A total loss of power is not considered credible, in view of the reliability of the Saxton plant power supplies. If only the rain supercritical power supply fails, the situation is handled similar to the loss of flow with the standby pump operable.
III-$t 2 53 Loss of coolant Loco of coolant vould result from the rupture of a pipe or component in the supercritical loop process stream. Corrective actions taken depend upon the location of the break.
If the rupture is between the loop pump and the pressure tube inlet, reactor scram is initisted by a reversal of pressure differential across the pressure tube. Injection of vater from the coolant reservoir into the pressure tube outlet line begins on the same signal. When the coolant reservoir is empty, the emergency condenser is placed in service by the operator to keep the fuel assembly cool until the reactor can be cooled down.
For ruptures downstream of the pressure tube, a reduction in the pressure tube inlet pressure scrams the reactor. Continued operation of f.he loop pump cools the fuel assembly.
When water supplies in the head tank and reservoir are exhausted, cooling is continued by manual operation of the emergency condenser.
In the unlikely event that a break occurs in the pressure tube itself, r8 ctor scram is again initiated on low pressure and safety injection functions as previously described. After the coolant reservoir is empty, manual operation of the emergency condenser and/or natural circulation of reactor coolant vill prevent gross melting of the fuel element cladding.
If the rupture is in the short sections of pipe between the pressure tube and the emergency condenser connections, flow to or from the condenser is interrupted, and cooling of the fuel assembly by natural circulation is prevented. After_ the coolant reservoir is empty, service water at low pressure is automatically supplied to the fuel assembly through one of the injection lines. Residuni heat generated in the fuel is removed by boiling this vater until the plant can be shut down and the pressure tube removed.
III-5: 3 5.h Loss of Component Coolinc Water The first sign of loss of component cooling vster is an alam on high temperature at the high pressure cooler outlet. Upon verifying the loss '
of coeling vater, the operatcr turns off the heater, manually increases loop flov to its mximum value and begins nomal shutdown of the reactor.
If cooling water supply is re stcred, nomal operation resumes. Otherwise, the plant is cooled down and the necessary repairs perfomed.
55 Pemoval of the Pressure Tube In the event of cladding f ailure, the loop vill became contaminated. In order to prevent the spread of contamination that vould result if only the fuel acaembly were removed, it is planned to remove the entire pressure tube. Using the planned precedures outlined in Section III-4.2, the super-critical loop, excluding the pressure tube, can be readily decontaminated.
To remove the pressure tube and fuel as a unit, it must be foolsted from the rest of the loop. Because of the possibility of high radiation in the region of the pressure tube, its removal must be accomplished remotely.
Valves H0-X-24, 26 (see Pig. II-1) have been closed and valve HC-X-25 has been opened to isolate the pressure tube, provide emergency cooling for the fuel and allow clean up of the remainder of the loop.
"Jne pressure tube isalation valve and inlet block valve on the inlet jumper are closed. The remotely operated Grayloc connection just upstream of the inlet block valve is then broken. The block valve on the outlet jumper is then closed and the remote Grayloc downstrea'n of it broken.
The precsure tube is now free from the loop and may be removed from the reactor by breaking the Conoseal joint at the reactor vessel head. The by-pass valve between the inlet and outlet jumpers vill act as a pressure relief valve while the pressure tube is being stored in the storage pool.
No pressure build-up is expected in the pressure tube during this storage period because of heat transfer to the storage pool vater. Any releases-of activity through this valve would be very small and would be removed i
by the storage pool clean up system.
The contaminated pressure tube vill be stored in the storage vell until l it hea cooled, when arrangements can be made for its disposal.
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IV: 1
, IV, ACCIDEffr AfMLYSIS j
The installation and operation of the supercritical loop does not-alter the probability, nature, or consequences of the accidents previously reviewed by the ADO for the Saxton reactor.
Fuel cladding defects may occur during operation of the supercritical loop.
The occurrence of such defects vill in no vny affect the integrity of the super-i critical coolant- rystem. Fission products released vill be effectively contained in the supercritic31 cooktnt and purification systems and in the Saxton radio-active vaste dinpocal system. A radiation monitor is provided to alert the operator of a rise in supercritical coolant activi.. While care is exercised to avoid gross cladding defects, such occurrences vill not constitute a hazard to the operating personnel or the public.
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Calculations for a gross fuel failure with the supercritical coolant system intact show that, within 214 hours0.00248 days <br />0.0594 hours <br />3.53836e-4 weeks <br />8.1427e-5 months <br />, the operation of the supercritical loop purification system as described in Section 4.2 can reduce radiation levels to normal design levels in the reactor containment. The requirements for purifica-tion and cleanup of the loop are vell vithin the capabilities of the Saxton Vaste Disposal Facility. Discharges to the environment vill not exceed the limits of AEC Standards for Protection against Radiation, 10 CFR 20.
The only conceivable mechanism for releasing fission products to the reactor containment is a loss of coolant accident. The consequences of the loss of coolant accident, either in the Saxton reactor, the supercritical loop, or both combined, do not exceed those of the maximum hypothetical accident previously reviewed for the Saxton reactor.
If a loss of coolant vere to occur to the Saxton reactor, scram would be initiated and the Saxton reactor safety injection system would keep the core covered at all times, adequately protecting the pressure tube, b __
. g IV: 2 In the unlikely event cf a loss of coolant to the faxton reactor folloved by failure of the Saxton ' e' t er safety injection, the reactor core veuld be shut down ty scram and 39,c cf moderator and core melting would begin apprcxinntely three minutec aft 1r the accident. Continued lov temperature suberitical coolant fiev through the pressure tube vould probably protect the supercritical fuel and precoure tute. If the pressure tube failed, the supercritical loep cc:lant vould flow throuch the break and escape into the Saxton reactor. The supercritical loop pump would continue to pamp coolant through the pressure tube into the Saxton reactor at a rate of 15 gpm, or if both the loop and standby purpo are eperat ed, at a rat e of .:0 3 gpm. The supercritical loop coolant vould flash into steam and escape to the reactor containment. The effect cf this flow on the react er ccnteinment pressure transient is negligible and does r.ct increase the peak contaira::ent precoure.
If a ]cos of ecolant were to occur in the supercritical leop, 000 of twc actiens v;uld be taken automatically. If the break occurred downstream cf the precoure r
tube, low pressure at the pressure tube outlet would scram the react er, so and an
' alarm and shut cff the supercritical 1 cop heaters. The loop pump voald continue to deliver normal loop flow using water from the head tank. The operator can actuate the emergenev cool'ag system, utilizing the emergency condenser, which is dec1gned to provid . equate cocling to handle decay neat thus protecting the supercritical core and preccure tube.
If the break occurred upstream Of the pressure tube, the flow through the pressure tube vould be reversed. The flow reversal vould cause reactor scram, initiation of safety injec+,ien ar.d closing of the pressure control vslve between the high and low pressure coolers. The safety injection f.lov enters the super-critical ecclant loop at the normal outlet of the pressure tube. Vnen the c:olsr.t l
reserv?ir is nearly empty, the safety injection is automatically switched to the askeup vater supply. The cpe rator can also actuate the emergency coc2ing i
system. Tne safety injection provides adequate ecoling to protect the super-critical core and the pressure tube.
1 IV: 3 !
A rupture of the preanure tube during operation is very unlikely because of the concervative design basic used and outlined in Section II-4.2. In the event of such an occurrer.ce, the Saxton reactor vould be able to withstand cuch a failure and still be able to shut dcun and prevent extensive core damage.
An innantaneous lose of coolant in both the cupereritical loop and the Saxton reactor cimultaneously would result in a contaire.ent vconel mximum pressure lecc thar.1 poi creater than that evalunted for the Saxton reactor maximum hypo-thetical accident. The volume of the supercritical loop is 60 gallons compared t o 2hCO gal.lonc for the Saxton primary cyctem. The contained energy 10 in approximately the came ratio, hence the small incrence in maximum pressure.
With the came acou =ptions, the release of fission products to the containment vecrel vould not be Breater than that evaluated for the Sarton reactor maximum hypothetical accident. The accident ic extremely remote and its conse quences are negligibly different from those of the Sarton reactor maximum hypothetical accident.
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