ML19317F445
| ML19317F445 | |
| Person / Time | |
|---|---|
| Site: | Oconee  |
| Issue date: | 06/28/1973 |
| From: | Thies A DUKE POWER CO. |
| To: | Schwencer A US ATOMIC ENERGY COMMISSION (AEC) |
| References | |
| NUDOCS 8001140682 | |
| Download: ML19317F445 (13) | |
Text
{{#Wiki_filter:.. e-i e DUKE Pownn COMPANY Powen Dust.orwo 4::e Sourn Gnuncu Srnerv, CHAntarrr.,N.C. eseos P.o.Dox sa7e A. C.164stS sa=som v ca emisioa=, PocowCteou ano Teensase6ssose June 28, 1973 e Mr. Al Schwencer, Chief Pressurized Vater Reactors, Branch 4 Directorate of Licensing U. S. Atomic Energy Cottmission Washington, D. C. 20545 Re: Oconce Nuclear Statfor. Docket Nos.' 50-270 and -287 Subcompartment Pressure Analysis o
Dear Mr. Schwencer:
Please refer to my letter of March 2,1973 which transmitted at'your request additional Information concerning the analysis of the. reactor cavity and steam generator subcompartment pressure respo.nse to' loss-of-coolant accidents. Since the March 2 letter, we have performed additional analyses for these areas and wish to submit the analysis results. Therefore, please find attached a June 26, 1973 revision to "AEC Request for Additional information, Subcompartment Pressure Analysis, Oconce Nuclear Station, Units 2 and 3." This information will be included.in the next revision of the Oconec Final Safety Analysis Report. Very truly yours, g.h_~.*'f.,g. A. C. Thics ACT:vr Attachment h 4 e W * " ' ' * * ' * * ' ~ " * * * ^ L'-
e OCONEE NUCLEAR STATION UNITS 2 AND 3 AEC-REQUEST FOR ADDITIONAL INFORMATION SUBCOMPARTMENT PRESSUR! ANALYSIS REVISED JUNE 26, 1973 -Question 1 1 Reanalyze the reactor cavity and steam generator compartments pressure response considering a homogeneous steam-water-air mixture with appropriate correlaticns for. sonic flow throu*gh the vents. A vent discharge coefficient of 0.6 should be used, and reactor blowdown calculations should assume a discharge coefficient of 1. Response (Reactor Cavity) The results of the reanalysis of the pressure response in the reactor cavity, considering a homogeneous steam-water-air mixture with appiopriate correlations for sonic flow through the vents are presented in Figure la dated February, The B&W CRAFT Code, utilizing a disch'arge coefficient of 1.0, was 1973. used to obtain the mass release rates data. The reanalysis of the reactor cavity pressurization was performed with the Bechtel COPRA Code, using the vent discharge coefficient of 0.6. The peak differential pressure for the 8.0 square feet hot leg break, which corresponds to the largest permissible break stated in the previous analysis,- was found to be 160 psi which is 78 percent of 205 psi, the design' pressure for the reactor cavity. The mass release rates, as determined by CRAFT, resulted in, reactor cavity pressures lower than those reported in the previous analysis. Response (Steam Generator. Compartment) The results of:the reanalysis of the pressur.e response in the steam 9enerator compartments,- cons?'. ring a homogeneous steam-water-air mixture with appropriate correlations for sonic flow through the vents are presented in The B&W CRAFT Code (latest version), utilizing
- Figure lb, dated June, 1973.
a discharge coefficient of 1.0, was used to obtain the mass release rates data. ~ . The reanalysis of the pressurization for the steam generator compartments was performed with the modified version of the Bechtel COPRA Code. The computed differential pressures for the W.1 square feet hot leg break in either the East or the West-Steam Generator Compartment are shown graphically in Figure Ib. The reinforced. concrete structural elements comprising the steam generator compartments were reanalyzed to determine the effect of the increased pressure . transients.- The structural integrity of the compartments is sufficient to withstand 130 percent of 'the peak.diiferential pressure transient of 15 psi ~ .in combination with the other structural loadings. ~.: h ~l ~;- -~ 4 qg
(
- w 2?.0,-
E 3 tcc' a 3 I 180 c, z .a, f gj iva l y- - go i ...... l. x a 4-n. 12.0 z.
{--
3 / 100 V- $ so -/ M / W Go ,.f.__..._.. _..._. p. %. sa. l E 40 L w 20 ~ ~ ~~~ ' f - - ~~ " -- y y' a. 0""** * ' I I II I'II I I I JI O. col O.010' o, loo l,o o o TIME t.7TER RUPTURE, SECONDS CURVE BREAK SIZE DESCRIPTION 2 1* 8 ft H.L. Roughly corresponds to maximum break size previously. ^ reported reactor cavity could withstand 2 2* 5 ft H.L. Intermediate' size break 3 3 ft H.L. Corresponds to maximum hot leg break which can occur within the reactor cavity 2 4 8.55 ft C.L. Corresponds to largest previously reported break of { l hot Icg +Although the 3 ft2 j break size is the ) reactor cavity, largest' possibic wit!hin' the trithin the cavity.it was conservatively assumed all of the break i s i . ' ~ Figure la. _a Presnure Transienta for Range of Rupture Sizes Within i Ei e c t ier (*a vi t y. - f hW D l
i 25 20 E a s
- m w
f 15 a5 n l 5 'l 6 O-i m f 10 l .Jg 6 S W 1 5 m I f ~ y E O 0.0 01 0.010 0,100 1.No TIME AFTER RUPTURE, SECONDS CURVE BREAK SIZE DESCRIPT10N' 5 14.1 ft2 H. L. '- Rupture of 36 inch hot leg in East Stcom Generator Compartment i 6 14.1 ft2 i H. L. Rupture of 36 inch hot l'eg'In West' Steam Generator Compartment 1 1 i. F giere b. .PressureTransientsforHotLegRuptu{es'I,n[53c Compartment. d tor ~! r ew 3.g % f o; s [ h6 l
l i ,e Question _2_ Describe the analytical model, including assumptions and appropriate he subcompartment pressure response. , bases, used,in calculating t . Response _ (Reactor Cavi ty)~ onse. The COPRA code v'as used to calculate the reactor cav ~ the computer program are contained in the following description. l Summary of Calculational Procedure. COPRA Computer Program: The equations and corresponding solutions are divided into The initialization phase sets up quantities such - ) " phases: or transient phase. au pressure, masses, and temperatures in the compartments' atmosphe The for the steady state just p'rior to the blowdown accident. tities . transient phase describes the transient behavior of these quan during and af ter blowdown. . c 1. Assumptions ~ The following assumptions are incorporated in the, analysis: ~ I The steam, water, and air throughout each compartment are a. l in thermal equilibrium at all times. j Water, steam, and air entering a compartment are mixed .l j homogeneously and instantaneously; no accumulation of b. vater occurs on the valls or in the sump. heat transfer to the containment valls or floor. ,4 - There is no c. The blevdown expands into Compartment 1 by. the following, First the mass expands isenthal-d. l thermodynamic process. The water J pressure. i pically to the total compartmenttime could form more steam only by present at that evaporation. The Cater is assumed to relatively slott undergo no further chringe of phase, maintaining thermal The steam then completes equilibrium with steam and air. its isenthalpic expansion to the partial pressure of the steam already in the compartment. If equilibrium calculations result in a superheated .e. Lisen a suGicicut quam.ity of the water sus-utmosphere, pended in the atmosphere is flashed into steam such that f L_
=. 'tha* atmosphere is just saturated, h enert,y to flash 1 the water' is taken frem the atmosphere. If all the sus-pended water was ever used up, the containment atmosphere vould remain superheated. f. For masses passing between compartments, the thermodynamics dif fers slightly. The steam-air-water entering from the 'other compartment will be brought to thermodynamic equilib- 'rium without the intermediate step of flashing at the total pressure. g. The mass flowing between the compartments is a homogeneous ' 'two-phase water-steam-air mixture. The flow equations, in 1 addition, assume a frictionless, compressible, adiabatic, no-slip model. .+ ry, <h. ' Sharp-edged orifice flow equation is used. s, i. The first law of thermodynamics for an open system with 'no -heat transfer as applied to each compartment is: O E,, dMi h,g d, i de where: Total system energy ,E = dM, = Mass transfer into compartments g e Enthalpy of mass being transferred ,h = 2. Initi.alization Prior to blowdown, the containment system is assumed to be in a steady -state condition. Using this assumption, the initialization. phase determined the partial pressures, masses, and energy con-tent of the air and water vapor in the containment atmosphere. 3. Transient Phase a. General Description l ~ The description of 'the transient phase begins with a description of the sequence of the various steps at the ~ time advance followed by a detailed description of each step. ' Initially the time (t) vill be set' equal' to zero cud the advancement over the interval de vill be' frota cteady-state conditions. Mass calculated as leaving Compartment 1 during a time step does not enter Compartment m f$ c 0
2 until the following time step. A time advance is started by' determining dt and updating t. Next the blowdown input is ~ determined as the average cf the blowdown at the beginning and end of a time step. The blowdown mass is then spilt into liquid and vapor components, if any water dropout is specified it is then removed from the water input to the particular compartment. ~ ' The masses are'then added to the compartments and their respective final thermodynamic states determined, if, at the end of a time step, either compartment is superheated, and if there is water in suspension in that compartment, then a sufficient quantity qf that water is flashed to just saturate th'e atmosphere, if insufficient water is present to saturate the atmosphere and if water were removed from the atmosphere during that time step, then that water' is also used to saturate the atmosphere. If all available water is exhausted and the atmosphere is still not saturated, then the atmosphere is allowed to remain superheated, b. Flow Equations g l Flow equations used are those originally ' developed for single phase,. perfect gas flow (References 1, 2, and 3). Solution of Energy Balance Equation c._ This calculation determines the final temperature and pressure in each compartment. The thermodynamic balance for each compartment, is done by the same routine and the procedure is identical. if, the atmosphere is superheated, then a portion of the suspended water is vaporized to just saturate the atmosphere. This portion is obtained by an iteration process. If insufficient water is present in the atmosphere to saturate the atmosphere, it is then allowed to 'superheat. Response, (Stearr Generator Compartment) COPRA Computer Program: Modified Version A modified version of'the Bechtel Computer program, COPRA, was used for the steam generator compartment pressure transient analysis. The program solves the continuity equation, the energy and momentum conservation equations, and the equations of state. The program can accommodate a maximum of one hundred control' volumes and 5 flow paths from each control volume. The program will select the control volume cnd flow path configuration that results in the best representation of the pressure transients in the compartments along the flow paths f rom the first compartment to the dvanstream compartments. in which the The blowdown data is added in time increments to the Co.vgartment line break is postulated. ~The program solves the conservation equation and equations of state to determine the thermodynamic state in the Compartment. The no..entum equat ion is them solved for cacii flow path to obtain the fic,w during each time step from the Compartment to each connected compartment. The conwcvation ei uation and equatiops of stoie are egaisi solved to determine the _' l thconodynamic st.ite in the compartment for the beginning of the next time D D ~~
increment. This procedure is repeated in sequence for~ cach compartr,cnt except that the flow f rom the upstream compartments replaces the blowdown. The pres-sure in each compartment is calculated using the total mass and energy in that compartment after the flow from the upstream compartments ('or the blowdown) has been added to the inventory of mass and energy in that compartment. The equi-librium thermodynamic state is considered determined when the search tempera- .ture provides properties such that the ratio of the difference between the trial energy balance and the energy inventory to the trial energy balance is sufficiently small. The compressible fluid flow equation is used for.the analysis of steam genera-tor compartment pressurization. The vent areas and associated flow coeffici-ents are listed in the following tabulation: Location West East _ Coefficient ; Top 528 417 Varies (0.66 to 0.782) 4 l Bottom 522 522 0.85 i Cross Comp. 116 116 Varies (0.66 to 0.777) Cross Comp. _1,333'ft2 167 167 0.60
- 1,222 ft2 The coef ficients which are calculated by the computer code (the top and cross compartment coef ficients) are plotted in Figure B-4, for the cast steam gener-ator compartment.
References ~ 1. Buckingham, E., " Note on Contraction Coefficients of Jets of Gas", USNES Journal of Research, Vol. 6, 1931, p. 765. 2. Cunningham, R. G., "Supercritical Compressible Flow Through a-Square-Edge Orifice", Midwest Conference on Fluid Dynamics, 1950. 3 Perry, J. A., " Critical Flow Through Sharp-Edge Orifices", Trans. ASME, October, 1949, p. 757 4. Vennard, " Elementary Fluid Mechanics", John Wiley, N. Y., N. Y., / 1954. Question 3 Provide the mass and energy blowdown rates as a function of time and location used in the analysis. _ Response ~~ The mass and energy blowdown rates based on B&W CRAFT Code (latest version) ., is presented in Figures C-la and b with the accompanying table. i hh ? r { l i [
1 ^ 0 1 ~ T 9 S lA E o O O T T T. TN N E E M a. T T RT o R AN A PE P MN M OT O CR C A RP 7 ~ a 0M d T,O o T AC A R R ER E NO N ET G -GA E R T ME 6 AS hN AE EE 0 EM TG TN S SI M A TA TT SE ) SN AT A0 ES 5 c h{ e h o S ( j E M I T 4, 0 N ~ g ~ 3 I ,o 4' O L F 2 L I A o C I T I R C i O y i - i -l 1*I i 'o 2 6 7 6 5 4 3 I 0 o o o o 'O 0 O g_2 nm sq, O N=i ._ m j 9o m ?. ;a - OE o E 7. S1 5 oQ e,. i, o Tz* 1 ,o m y '5 O nO y g3~J E ' m,O 33* e >2%I r W G6eG d(c6c
- y
,; 7\\ I;:
- l
,l
i I l -i TABLE FOR FIGURES C-la & b i KEY TO BLOWDOWN DATA i CASE.*, EXPLANATION 2 14.1 ft rupture'in 36-inch 1 hot leg - 8 ft rupture in 36-inch -i 2 2 hot leg' 2 3 - -. A 5 ft rupt6re in 36-i'nch ~ hot leg !~ 2 4 3 ft rupture in 36-inch hot icg 2 '5 8.55 ft rupture in 28-inch cold leg e .f I 4 4 I / e e 4 e e ~ a g S. l l J '{ m
4 O s 0 ~ (4 l\\ I t-l / g f s O a tn g. 8 m 9 d e rJ 'o N T / l ~ ln I 111 I l li 1 111 1 I I I I .. o 2 a = o O ~ o EllERGY MATE--Etu/llR rigure C-lb. Energy Blowdown Rate for ilabcock and Wilcox Blowdown Data.
- Curve (1) revised *in accordance with B & W Data of June I, 1973 i.-. -
\\
7 = _0_uestion 4 Discuss'the analyses used to justify that the break locations select d result in the highest calculated pressures, e correlations used~for determining subcooled blowdown rates. include a description
Response
_ Reactor Cavity A hot leg and cold leg pipe break was analyzed to determine the worse break location'. the area is equivalent to that of a guillotine break.An 8.55 squar hot leg break was analyzed since this is the largest break size that A 3.0 square foot occur in the reactor cavity. can _Stcom Generator Compartment legpipebreakwithanar;aequivalent A hot plus.a simultaneous break of tre Pressurizer surge pipe was used forto a the analysis. The hot leg is System and its rupture results in the highest mass and energy surge pipe, the energy release from the surge pipe was rates. ease e surizer, The blowdown rates were calculated using the Moody correlation with CD = 1.0, as explained in BAW - 10030, CRAFT . Description of.Model for a Equilibrium LOCA Analysis Program, October,1971. ~ i _0uestion 5 reabtor vessel for break' within the reactor cavity. Provide s s on the _ Response ,.The reactor vessel is supported by a cylinder which is welded to the v shell and which extends downward to a flanged base ring that / the base slab of the reactor building. is bolted to underside of the vessel is not subject to significant uplift forcesAs a result o Question 6 Provide the results of an analysis of the jet forces which can l the reactor cavity and stcom generator structures ad!ag on
Response
i A rupture of the hot leg pipe with a flow area equivalent to one pip opening was used for the analysis. This pipe e diameter System, and its jet impingement force will be the highest.is the largest in the R. C. blowdown rates and exit plane pressures supplied by B& The jet impingement n using the mass The steady.:ste jet t
impingement force ~is 2 million pounds. The jets, when impinging on structures .v' cor_. equipment are' assumed to spread within a 10 degree half-angle. Jet impingement forces-are assumed to traverse open areas without diminuition of forces. -The structures exposed to jet Impingement are designed to withstand the effect of the jet from the postulated accident. e t e 99 9 e G Y e 9 C e s 5 G D De 0 f e e e b b g , s h 4 f f f ',s + .-}}