ML031970742
| ML031970742 | |
| Person / Time | |
|---|---|
| Site: | Oconee  |
| Issue date: | 07/07/2003 |
| From: | Canady K Duke Energy Corp, Duke Power Co |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| Download: ML031970742 (98) | |
Text
P Duke Duke Energy Corporation rSowere 526 South Church St.
A A DukerEwW ConmpanyEC8 Duke Eneryj CompanyCharlotte, NC 28202 EC08H P.O. Box 1006 Ken Canady (704)3824712 OFFICE Vw Psnt (704)382-7852 Fx Nuclear Engineering July 7, 2003 Document Control Desk U. S. Nuclear Regulatory Commission Washington D. C. 20555-0001 ATTENTION: Chief, Information Management Branch Division of Program Management Policy Development and Analysis Staff
Subject:
Duke Energy Corporation Oconee Nuclear Station - Units 1, 2, and 3 Docket Nos. 50-269, 50-270, and 50-287 Revisions to Topical Report DPC-NE-3003 In Support of Steam Generator Replacement Response to NRC Staff Request for Additional Information
Reference:
Duke Submittal Dated June 13, 2002 Enclosed herein, please find the Duke Energy Corporation (Duke) response to the May 12, 2003 NRC staff's request for additional information concerning topical report DPC-NE-3003, Revision 1, "Mass and Energy Release and Containment Response Methodology." to this letter constitutes Duke's response to questions 1 - 12, and 14 - 17. Duke's response to question 13 will be submitted by July 31, 2003.
During the preparation of the responses, two (2) additional revisions to the methodology were identified as necessary.
These new revisions are detailed in Attachment 2. Duke requests that the NRC include these revisions within the scope of review of the original June 13, 2002 submittal.
If there are any questions or if additional information is needed on this matter, please call J. A. Effinger at (704) 382-8688.
t/4XiD
U. S. Nuclear Regulatory Commission July 7, 2003 Page 2 Very truly yours, K. S. Canady xc:
L. A. Reyes, Regional Administrator U.S. Nuclear Regulatory Commission, Region II Atlanta Federal Center 61 Forsyth Street, SWW, Suite 23T85 Atlanta, GA 30303 L. N. Olshan, NRC Project Manager (ONS)
U.S. Nuclear Regulatory Commission Office of Nuclear Reactor Regulation Mail Stop 08-H12 Washington, DC 20555 M. C. Shannon, NRC Senior Resident Inspector (ONS)
U. S. Nuclear Regulatory Commission July 7, 2003 Page 3 bxc w/o attachments:
R. 0. Sharpe L. E. Nicholson G. B. Swindlehurst M. T. Cash G. W. Hallman J. A. Effinger ELL
ATTACHMENT 1 RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION
Attachment 1 Duke Power Response To Request For Additional Information DPC-NE-3003 Revision 1 "Mass and Energy Release and Containment Response Methodology" General Ouestions
- 1. Discuss the major differences between FATHOMS and GOTHIC 7.0 and the effect these differences will have on the containment analyses.
Response: FATHOMS Version 2.4 was released in April of 1989. Shortly thereafter, FATHOMS became the GOTHIC code under EPRI sponsorship. Since then there have been many versions of GOTHIC released as part of the ongoing GOTHIC Enhancement Project. Each new version of GOTHIC adds new modeling features, user conveniences and improves and extends existing modeling capabilities. The list of differences between FATHOMS 2.4 and GOTHIC 7.0 is extensive but only a few of the differences are of significance for Duke's application for the analysis of the temperature and pressure response in containment for the Oconee Nuclear Station. These differences are described below.
Drop Energy Equation FATHOMS 2.4 solves one energy equation for the vapor phase (air and steam) and a second energy equation for the combined drop and liquid phases. This means that within each computational control volume the drops and the liquid phases are at the same temperature. One of the first modifications under the GOTHIC project was the addition of a separate energy equation for the drop field. With this improvement, the drops and liquid phases within a computational control volume can be at different temperatures. If drops are present, the combined dropliquid energy equation in FATHOMS 2.4 generally tends to promote thermal equilibrium in the liquid and vapor phases. The large interface area of the drops effectively extends the interface area for the water pool or films, enhancing the interphase heat and mass transfer.
Drop Deposition Both FATHOMS 2.4 and GOTHIC 7.0 include models for the drop deposition.
However, for the Oconee applications, the FATHOMS model is limited to gravitational settling using a constant drag coefficient appropriate for large drops. This makes the settling rate independent of the drop size. The drop deposition model in GOTHIC 7.0 includes gravitational settling and impaction. Deposition due to impaction is small for this application because the bulk average containment velocity is low. The settling deposition in GOTHIC 7.0 depends on the drop diameter because the drag coefficient is a function of the drop size. Small drops, typical of the size created by a LOCA, will fall slower in GOTHIC 7.0 due to the larger drag coefficient. Therefore, the water retained as drops in the atmosphere will typically be larger with GOTHIC 7.0 than with FATHOMS 2.4. GOTHIC 7.0 also includes a drop agglomeration model whereby smaller drops combine to form larger drops that are subject to higher fall out rates.
1-1
Drop Entrainment Both FATHOMS 2.4 and GOTHIC 7.0 include models for drop entrainment. Typically drop entrainment occurs at high vapor velocity across a liquid surface. The bulk average velocities calculated for Oconee applications are not high enough to result in significant entrainment. However, GOTHIC 7.0 includes another entrainment mechanism that is not in FATHOMS. In GOTHIC 7.0, a portion (1/6) of the condensation rate is assumed to be converted to drops to simulate dripping from ceilings and equipment. The model was incorporated to improve comparison with experimental results from HDR and other large-scale facilities. The drops created by this mechanism are large and quickly fall from the atmosphere but they do provide the potential for increased interface heat and mass transfer.
Interphase Heat and Mass Transfer In FATHOMS 2.4, the interface heat and mass transfer at the drop and liquid surfaces is calculated using effective heat transfer coefficients for each side of the interface that incorporates mass transfer as appropriate. The particular correlation used for the effective heat transfer coefficients depends on whether the phase is superheated or subcooled relative to the local saturation temperature. The energy balance at the interface used to calculate the rate of phase change is rAhor = Al HI,ff, (T. - T) + Al Heff (TV - Ts where r is the rate of phase change, Ah. is the heat of vaporization, A, is the interface area, H. as and H,.cff are the heat transfer coefficients, including phase change effects, for the liquid and vapor sides of the interface respectively. T, T, and T, are the liquid, vapor and saturation temperatures, respectively.
In GOTHIC 7.0, the interfacial heat and mass transfer are calculated using a heat and mass transfer analogy. The energy balance for the interface is rAhr =AH,(T, -T,)+AlH.(T-T,)
where H, and H, are the sensible heat transfer coefficients for the liquid and vapor sides of the interface respectively and T, is the interface temperature. The unknown interface temperature is obtained by simultaneously solving the interface energy balance with the mass transfer equation rP=-Al H ( - VI) and the assumption that the steam pressure at the interface is the saturation pressure at the interface temperature. H is the mass transfer coefficient and V, and A, are the steam concentrations in the vapor phase and at the interface, respectively.
The heat transfer coefficients are from correlations for free and forced convection as appropriate for the local conditions. The mass transfer coefficient is obtained from the heat transfer correlations using a heat and mass transfer analogy. The formulation for the interface heat and mass transfer in FATHOMS tends to keep the phases closer to thermal 1-2
equilibrium than the GOTHIC formulation. The interface area is largely dependent on the flow regime that the code determines is appropriate for the given situation. Although there have been changes to the flow regime selection logic in GOTHIC, for this application the interface area would be based on an assumed film regime configuration and should be approximately the same for the two codes.
Observed Differences in Code Predictions A comparison of the code results from FATHOMS 2A and GOTHIC 7.0 for the Oconee cases shows that for LOCA:
- 1. GOTHIC 7.0 predicts peak pressures that are generally slightly lower (-0.5 psia)
- 2. GOTHIC 7.0 predicts peak temperatures that are generally slightly lower
(-0.50 F)
For MSLB:
- 1. GOTHIC 7.0 predicts peak pressures that are generally slightly higher (-0.5 psia)
- 2. GOTHIC 7.0 predicts peak temperatures that are generally lower (-10° F)
For MSLB and LOCA:
These differences are consistent with the code differences. For the LOCA events both codes predict a saturated containment atmosphere due to the large amount of drops injected. The slightly lower pressure and temperature from GOTHIC 7.0 may be attributed to additional drop hold up in the atmosphere. This effectively increases the heat capacity of the atmosphere and reduces the temperature rise for a given energy addition.
For the MSLB events, the higher pressure predicted by GOTHIC 7.0 may be attributed to additional steam generation from the improved interface heat and mass transfer models and from the drops that are generated due to dripping. The additional vaporization takes heat from the atmosphere and reduces the atmosphere temperature.
The lower sump liquid volume predicted by GOTHIC 7.0 may be attributed to higher drop concentrations in the atmosphere due to larger drag on small drops and drops generated by the dripping model. The lower sump temperature predicted by GOTHIC 7.0 may be attributed to the addition of the second energy equation for the drops and the improved heat and mass transfer models in GOTHIC 7.0.
The code changes discussed above were all directed toward providing a more realistic and physically based solution for accident events. All of the model improvements were made in conjunction with code and model validation. The validation base for GOTHIC 7.0 is significantly greater than for FATHOMS 2.4 and code results are generally in good agreement with experimental data.
1-3
- 2. How is the nitrogen released from the accumulators accounted for in the containment LOCA calculations?
Response: The nitrogen cover gas injection boundary condition in the long-term large-break LOCA containment response is described on pg. 6-20. A constant nitrogen flow rate of 356 Ibm/sec is assumed from t=37.6 to 44.5 seconds for the injection of this gas. This boundary condition is also included in the peak containment pressure analyses. Because the peak containment pressure is reached prior to the time at which this gas is injected into containment for all cases analyzed, it has no impact on the calculated peak containment pressure.
The determination of the core flood tank initial conditions to maximize the containment pressure is discussed on pgs. 3-5 and 3-6.
- 3. Please provide the results using the GOTHIC 7.0 code of peak pressure and temperature calculations for the sensitivity cases listed in Table 3.1-1 of DPC-NE-3003 in tabular and graphical form. If the results or conclusions are significantly different from those presented in DPC-NE-3003P, explain the difference.
Response: Table 3.1-1 of DPC-NE-3003 describes a spectrum of LOCA peak pressure cases including a range of break locations and sensitivity analyses for several important modeling assumptions. The staff's request is understood to focus on the difference in the predicted results from the FATHOMS and GOTHIC 7.0 code versions. Rather than show the comparison for the cases in Table 3.1-1, a different set of cases has been selected which is more focused on the current knowledge of the key sensitivity parameters. Also, the results presented are for the ROTSGs, which is the subject of Revision 1 to the topical report.
The results of the 14 code comparison analyses are shown in Table 3-1 below and in the figures that follow. In general, the pressure and vapor temperature response predictions were very similar in both magnitude and trend. GOTHIC 7.0 predictions for peak pressures and vapor temperature were slightly lower (-0.5 psig and 0.5 0 F). These differences are consistent with the code model differences described in the response to Question #1. Both codes predict a saturated containment atmosphere due to the large amount of drops injected. The slightly lower pressure, vapor temperature, and liquid temperature from GOTHIC 7.0 may be attributed to additional drop hold up in the atmosphere. This effectively increases the heat capacity of the atmosphere and reduces the temperature rise for a given energy addition. A comparison of the total liquid and drop masses, and liquid temperatures, show the predictions of the two codes to be essentially the same. This is consistent with the changes in the drop deposition and entrainment models discussed in Question #1. These results show that the two code versions give essentially similar results for the same break location and initial and boundary conditions.
14
Table 3-1 Peak Containment Peak Containment Pressure (psig) Temperature (Di)
ROTSG Case Description Fathoms Gothic 7.0 Fathoms Gothic 7.0 Hot Leg SG Inlet Break w/ High RCS Flow Cases 14.1 ft2 HotLegBreakw/MI Pump 57.83 57.41 282.77 282.41 Degradation Model 14.1 ft2 Hot Leg Break w/ M3 Pump 58.03 57.63 283.02 282.67 Degradation Model 14.1 ft2 Hot Leg Break w/ Sensitivity to 57.99 57.60 282.98 282.64 Steamline Superheat 14.1 ft2 Hot Leg Break w/ Sensitivity to 58.48 58.09 283.56 283.22 Main Feedwater Hot Leg SG Inlet Break on a 50 ATcold Loop Cases 14.1 ft2 Hot Leg Break 50 ATcold Loop 57.68 57.28 282.60 282.25 Case 1 14.1 ft2 Hot Leg Break 50 ATcold Loop 57.88 57.48 282.84 282.49 Case 2 Hot Leg SG Inlet Break w/ Low RCS Flow Cases 14.1 ft2 Hot Leg Break w/ M1 Pump 58.02 57.59 282.99 282.62 Degradation Model 14.1 ft2 Hot Leg Break w/ M3 Pump 57.76 57.37 282.70 282.35 Degradation Model Hot Leg RVOutlet Break w/Low RCS Flow Cases 14.1 ft 2 Hot Leg Break w/ M1 Pump 57.14 56.84 281.97 281.71 Degradation Model 14.1 ft2 Hot Leg Break wl M3 Punp 56.85 56.58 281.64 281.40 Degradation Model Hot Leg RV Outlet Break wi High RCS Flow Cases 14.1 ft2 Hot Leg Break w/ M1 Pump 57.16 56.87 282.00 281.75 Degradation Model 14.1 ft2 Hot Leg Break wI M3 Pump 56.87 56.59 281.65 281.41 Degradation Model Cold Leg Pump Discharge Break wi High RCS Flow Case 8.55 ft2 Cold Leg Break @ Pump Discharge 53.03 52.44 276.68 276.15 Cold Leg Pump Suction Break w/ High RCS Flow Case 8.55 ft2 Cold Leg Break @ Pump Suction 54.30 53.45 278.26 277.46 1-5
GOTHIC 7.0 - FATHOMS COMPARISON ROTSG LARGE BREAK LOCA (14.1 ft2 Break - SG Inlet - High Initial RCS Flow w/ Ml Pump Degradation Model) 60-50
-40 320 20 10 2 0 10 20 30 40 50 60 TIME (SECONDS)
GOTHIC 7.0 - FATHOMS COMPARISON ROTSG LARGE BREAK LOCA (14.1 ft2 Break - SO Inlet - High Initial RCS Flow w/ Ml Pump Degradation Model) 300 -
250 200 I-~ ~~0
-2 150-100
-Fathoms
-Gothic 7.0 0 10 20 30 40 50 60 TIME (SECONDS)
GOTHIC 7.0 - FATHOMS COMPARISON ROTSG LARGE BREAK LOCA (14.1 f Break- SG Inlet - High Initial RCS Flow w/MI Pump Degradation Model) 300-250 X-,:] J . 2 ~~~~~~~~~~~~----------------------..
60 ~ 150-100 B 50
- Fathom
--- Gothic 7.0 0 20 40 60 80 100 120 140 160 180 TIME (SECONDS)
GOTHIC 7.0 - FATHOMS COMPARISON ROTSG LARGE BREAK LOCA (14.1 ft2 Break - SG Inlet - High Initial RCS Flow w/MI Pump Degradation Model) 600000 _
500000
'400000-o300000-0~~~~~~~~~00 200000.
100000 a0o8s o
- - - Gothic 7.0 0 20 40 60 80 100 120 140 160 180 TIME (SECONDS)
GOTHIC 7.0 - FATHOMS COMPARISON ROTSG LARGE BREAK LOCA (14.1 ft 2 Break - SG Inlet - High Initial RCS Flow w/ M3 Pump Degradation Model) 60
.40-0 10 0 10 20 30 40 50 60 TIME (SECONDS)
GOTHIC 7.0 - FATHOMS COMPARISON ROTSG LARGE BREAK LOCA (14.1 ft2 Break- SO Inlet - High Initial RCS Flow w/ M3 Pump Degradation Model) 300 -
250 200 150 100 0 10 0Fathoms 50 . . . . . . . . . . . . . . . . . . .
0 10 20 30 40 50 60 TIME (SECONDS)
GOTHIC 7.0 - FATHOMS COMPARISON ROTSG LARGE BREAK LOCA (14.1 ft2 Break - SG Inlet - High Initial RCS Flow w/ M3 Pump Degradation Model) 300 250
,Xf~~~~~ -
0 200 I-150 i 100 50
=-Fathoms
- - - Gothic 7.0 0
0 20 40 60 80 100 120 140 160 180 TIME (SECONDS)
GOTHIC 7.0 - FATHOMS COMPARISON ROTSG LARGE BREAK LOCA 2
(14.1 ft Break - SG Inlet - High Initial RCS Flow w/ M3 Pump Degradation Model) 500000 450000 400000
, 350000 m
g 300000
¢4 O 250000 04 0 200000
+
- y 150000 a
100000 FTathoms
--- Gothic 7.0 50000 0 I . . . . . . . . . . . . . . . . . . . . . . ... . . . ...
0 20 40 60 80 100 120 140 160 180 TIME (SECONDS)
GOTHIC 7.0 - FATHOMS COMPARISON ROTSG LARGE BREAK LOCA (14.1 ft2 Break - SG Inlet - High Initial RCS Flow w/ Sensitivity to Steamline Superheat) 60 --- 1--------_
50 40
-~~~~3 0
10 0120340Gothic 7.0 0 . . . . . . . . . . . . . . ....
0 10 20 30 40 50 60 TIME (SECONDS)
GOTHIC 7.0 - FATHOMS COMPARISON ROTSG LARGE BREAK LOCA 2
(14.1 ft Break - SG Inlet - High Initial RCS Flow w/ Sensitivity to Steamline Superheat) 300 250
! 200 IX 150-100 FTathonms
- -- Gothic 7.0 50 . . . . . . . . . . . .
0 10 20 30 40 50 60 TIME (SECONDS)
GOTHIC 7.0 - FATHOMS COMPARISON ROTSG LARGE BREAK LOCA (14.1 ft2 Break - SG Inlet - High Initial RCS Flow w/ Sensitivity to Steamline Superheat) 300 250 -- --- -- ------ -- --- --
150 t 100-50-
-Fathoms
--- Gothic 7.0 0 . . . . . . .. . . . .. . . .. . ... I .
0 20 40 60 80 100 120 140 160 180 TIME (SECONDS)
GOTHIC 7.0 - FATHOMS COMPARISON ROTSG LARGE BREAK LOCA (14.1 f Break - SG Inlet - High Initial RCS Flow w/ Sensitivity to Steamline Superheat) 600000 _ _
500000 5400000 X 0300000-100000 0 2 0 20 40 60 80 100 120 140 160 180 TIME (SECONDS)
GOTHIC 7.0 - FATHOMS COMPARISON ROTSG LARGE BREAK LOCA (14.1 ft2 Break - SG Inlet - High Initial RCS Flow w/ Sensitivity to Main Feedwater) 60-50-
~40O 00 ~ 30 -_ _ _ _
~20-10 -
l[- Fathoms
- Gothic 7.0 0 10 20 30 40 50 60 TIME (SECONDS)
GOTHIC 7.0 - FATHOMS COMPARISON ROTSG LARGE BREAK LOCA (14.1 ft' Break - SG Inlet - High Initial RCS Flow w/ Sensitivity to Main Feedwater) 300-250 200 9 150 100
- - -Gotic 7.01 50 0 10 20 30 40 50 60 TIME (SECONDS)
GOTHIC 7.0 - FATHOMS COMPARISON ROTSG LARGE BREAK LOCA (14.1 ft2 Break - SG Inlet - High Initial RCS Flow w/ Sensitivity to Main Feedwater) 300
.~~~~~~~~~~~~~~~~~~~~~~~~~~ - -... -----------
250 as A__
Z 200 1I--
8 E 150 PC" 100 50 l Gothic 7.0l 0
0 20 40 60 80 100 120 TIME (SECONDS)
GOTHIC 7.0 - FATHOMS COMPARISON ROTSG LARGE BREAK LOCA (14.1 ft2 Break - SG Inlet - High Initial RCS Flow w/ Sensitivity to Main Feedwater) 500000 450000 400000
, 350000 U,
g 300000 PA o 250000 A4 0
I~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
0 200000 g 150000 100000 Fadoms
- - - Gothic 7.0 1 50000 0
0 20 40 60 80 100 120 TIME (SECONDS)
GOTHIC 7.0 - FATHOMS COMPARISON ROTSG LARGE BREAK LOCA (14.1 ft2 Break - SG Inlet - High Initial RCS Flow w/ 5° ATcold Loop Case 1) 60 -_ _ _ _ __ _ _ _ _
50 420-0-
to ., l- --
Fathoms1 Gothic 7.0l 0
0 10 20 30 40 50 60 TIME (SECONDS)
GOTHIC 7.0 - FATHOMS COMPARISON ROTSG LARGE BREAK LOCA (14.1 ft2 Break - SG Inlet - High Initial RCS Flow w/ 5° ATcold Loop Case 1) 300 250
!200-2 150-100 50 . . . .
0 10 20 30 40 50 60 TIME (SECONDS)
GOTHIC 7.0 - FATHOMS COMPARISON ROTSG LARGE BREAK LOCA (14.1 ft2 Break - SG Inlet - High Initial RCS Flow w/ 5° ATcold Loop Case 1) 300-
£ 2 C A _ _ __-------------------------- ----- --
p200-50 W=W
'100 50 T-Fathoms
- - - Gothic 7 0 0 20 40 60 80 100 120 140 160 180 TIME (SECONDS)
GOTHIC 7.0 - FATHOMS COMPARISON ROTSG LARGE BREAK LOCA (14.1 ft 2 Break - SG Inlet - High Initial RCS Flow w/ 5° ATcold Loop Case 1) 600000-500000-
'4O0000
~300O00 5200000-0' 100000 0 20 40 60 80 100 120 140 160 180 TIME (SECONDS)
GOTHIC 7.0 - FATHOMS COMPARISON ROTSG LARGE BREAK LOCA (14.1 ft2 Break - SG Inlet - High Initial RCS Flow w/ 5° ATcold Loop Case 2) 60-50
~40O Pw30
~20-0 0
0 10 20 30 40 50 60 TIME (SECONDS)
GOTHIC 7.0 - FATHOMS COMPARISON ROTSG LARGE BREAK LOCA 2
(14.1 ft Break - SG Inlet- High Initial RCS Flow w/ 50 ATcold Loop Case 2) 300-250 0
t~ __
Fathomsl l--- Gothic 7.0l 10 20 30 40 50 60 TIME (SECONDS)
GOTHIC 7.0 - FATHOMS COMPARISON ROTSG LARGE BREAK LOCA (14.1 ft2 Break - SG Inlet - High Initial RCS Flow w/ 5° ATcold Loop Case 2) 300 X~~~~~~~~~~~~~~~~~-- l------- --------
250 0 200 P.-
t!j 00 E150 I . I = I ~ . . _
°00 50 0
0 20 40 60 80 100 120 140 160 180 TIME (SECONDS)
GOTHIC 7.0 - FATHOMS COMPARISON ROTSG LARGE BREAK LOCA (14.1 ft2 Break - SG Inlet - High Initial RCS Flow w/ 5° ATcold Loop Case 2) 600000 500000 ...... ____
d,400000-U, 200000-00 100000 oms 20 40-0 Gotc17.0 0 20 40 60 80 100 120 140 160 180 TIME (SECONDS)
GOTHIC 7.0 - FATHOMS COMPARISON ROTSG LARGE BREAK LOCA (14.1 ft2 Break - SG Inlet - Low Initial RCS Flow w/ Ml Pump Degradation Model) 60-50-10-:.
0 0 0-F4050s 0 10 20 30 40 50 60 TIME (SECONDS)
GOTHIC 7.0- FATHOMS COMPARISON ROTSG LARGE BREAK LOCA (14.1 ft2 Break - SG Inlet - Low Initial RCS Flow w/ Ml Pump Degradation Model) 300 -
250
! 200 150-100-1- Fathomsl 50 . . . . . . . . . . . .
0 10 20 30 40 50 60 TIME (SECONDS)
GOTHIC 7.0 - FATHOMS COMPARISON ROTSG LARGE BREAK LOCA (14.1 ft2 Break - SG Inlet - Low Initial RCS Flow w/ MI Pump Degradation Model) 300 250 L 200 I--
(La t4 l 150
- 100 50 0
0 20 40 60 80 100 120 140 160 180 TIME (SECONDS) v
GOTHIC 7.0 - FATHOMS COMPARISON ROTSG LARGE BREAK LOCA (14.1 f Break - SG Inlet - Low Initial RCS Flow w/ MI Pump Degradation Model) 600000 500000 t6 400000 0
in 300000 5 200000 0
100000 .. Fa~~~~~~~~~~~~~~~~~~~~~~~Pt
-A -- Gothic 7.0 0 1 . . . . . . . ~ I . . . . .
0 20 40 60 80 100 120 140 160 180 TIME (SECONDS)
GOTHIC 7.0 - FATHOMS COMPARISON ROTSG LARGE BREAK LOCA (14.1 ft Break - SG Inlet - Low Initial RCS Flow w/ M3 Pump Degradation Model) 60-50
.40 130__
p20 0
10 0 10 2030400Fathoms 0 10 20 30 40 50 60 TIME (SECONDS)
GOTHIC 7.0 - FATHOMS COMPARISON ROTSG LARGE BREAK LOCA (14.1 ft Break - SG Inlet - Low Initial RCS Flow w/ M3 Pump Degradation Model) 300 -
250-
- ~~200 150-100 l- Gothic 7.0 50 . . . .
0 10 20 30 40 50 60 TIME (SECONDS)
GOTHIC 7.0 - FATHOMS COMPARISON ROTSG LARGE BREAK LOCA (14.1 ft2 Break - SG Inlet - Low Initial RCS Flow wI M3 Pump Degradation Model) 300-250 p200-150 t
'100 50
- Fathoms
--- Gothic 7.0 0 . . . . . . I . . . . , . . . ._.. . . . . . . . . . . T 0 20 40 60 80 100 120 140 160 180 TIME (SECONDS)
GOTHIC 7.0 - FATHOMS COMPARISON ROTSG LARGE BREAK LOCA 2
(14.1 ft Break - SG Inlet - Low Initial RCS Flow w/ M3 Pump Degradation Model) 600000 - . .
500000-400000-J g 300000
@ 200000-100000 -.bom.
- -- Gothic 7.0 0 . . . . . . . . . . . . . . . . . . .
20 40 60 80 100 120 140 160 180 TIME (SECONDS)
GOTHIC 7.0 - FATHOMS COMPARISON ROTSG LARGE BREAK LOCA (14.1 ft2 Break - RV Outlet - Low Initial RCS Flow w/ MI Pump Degradation Model) 60-so 40 00 A30O
~20-0 0 . . . . .1.0.. . . . . . . . .
0 10 20 30 40 50 60 TIME (SECONDS)
GOTHIC 7.0 - FATHOMS COMPARISON ROTSG LARGE BREAK LOCA (14.1 ft 2 Break - RV Outlet - Low Initial RCS Flow w/ MI Pump Degradation Model) 300 250 20 09 150-100 0 10 20 30 40 50 60 TIME (SECONDS)
GOTHIC 7.0 - FATHOMS COMPARISON ROTSG LARGE BREAK LOCA 2
(14.1 ft Break - RV Outlet - Low Initial RCS Flow w/ MI Pump Degradation Model) 300 250 p 200 0
i 150 5
C, 100 50 X 4l 1 1 r Ahl l
-T athoms
- -- Gothic 7.0 0
0 20 40 60 80 100 120 140 160 180 TIME (SECONDS)
GOTHIC 7.0 - FATHOMS COMPARISON ROTSG LARGE BREAK LOCA 2
(14.1 ft Break - RV Outlet - Low Initial RCS Flow w/ MI Pump Degradation Model) 700000 -______
600000 -
500000-400000-o 300000-200000-100000 2 0 20 40 60 80 100 120 140 160 180 TIME (SECONDS)
GOTHIC 7.0 - FATHOMS COMPARISON ROTSG LARGE BREAK LOCA (14.1 ft2 Break - RV Outlet - Low Initial RCS Flow w/ M3 Pump Degradation Model) 60 -
50~
~40-30
{20 10 Fathoms
-- Gothic 7.0 10 20 30 40 50 60 TIME (SECONDS)
GOTHIC 7.0 - FATHOMS COMPARISON ROTSG LARGE BREAK LOCA 2
(14.1 ft Break - RV Outlet - Low Initial RCS Flow w/ M3 Pump Degradation Model) 300-250
!200-Fathiom
- - - Gothic 7.0 50 0 10 20 30 40 50 60 TIME (SECONDS)
GOTHIC 7.0 - FATHOMS COMPARISON ROTSG LARGE BREAK LOCA (14.1 ft2 Break - RV Outlet - Low Initial RCS Flow w/ M3 Pump Degradation Model) 300 250 - ------ -- -
=--------- -
p200-150-3100 50
- Fathoms
- -- Gothic 7.0 0 .240
. .0 . .10. .10 1 0 20 40 60 80 100 120 140 160 180 TIME (SECONDS)
GOTHIC 7.0 - FATHOMS COMPARISON ROTSG LARGE BREAK LOCA (14.1 ft2 Break . RV Outlet - Low Initial RCS Flow wI M3 Pump Degradation Model) 700000 600000-1500000 400000 2 4'
0o 200000-100000 --- Gti .
0 20 40 60 80 100 120 140 160 180 TIME (SECONDS)
GOTHIC 7.0 - FATHOMS COMPARISON ROTSG LARGE BREAK LOCA (14.1 ft2 Break - RV Outlet - High Initial RCS Flow w/ MI Pump Degradation Model) 60 - _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
50
~40-c% ~ 30 2
20 10 t~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ - -Gothic 7l 0010 20 30 40 50 60 0 10 20 30 40 50 60 TIME (SECONDS)
GOTHIC 7.0 - FATHOMS COMPARISON ROTSG LARGE BREAK LOCA (14.1 ft Break - RV Outlet - High Initial RCS Flow wI MI Pump Degradation Model) 300 250 200 0 150 0 .. .. .. . . . .
0 10 20 30 40 50 60 TIME (SECONDS)
GOTHIC 7.0 - FATHOMS COMPARISON ROTSG LARGE BREAK LOCA (14.1 ft' Break - RV Outlet - High Initial RCS Flow w/ MI Pump Degradation Model) 300-250 _ ---------
s~~~~~~sol A ~~~~~~~~~~~~~~--------------- - ------- -- -----I1 0 200-150 Fathomsl
- - - Gothic 7.0 0 20 40 60 80 100 120 140 160 180 TIME (SECONDS)
GOTHIC 7.0 - FATHOMS COMPARISON ROTSG LARGE BREAK LOCA (14.1 ft2 Break - RV Outlet - High Initial RCS Flow w/ MI Pump Degradation Model) 700000 -
600000-
§500000-
-, 400000-o 300000 0200000 10000 - - - Gothic 7.0 0
0 20 40 60 80 100 120 140 160 180 TIME (SECONDS)
GOTHIC 7.0 - FATHOMS COMPARISON ROTSG LARGE BREAK LOCA (14.1 ft2 Break - RV Outlet - High Initial RCS Flow w/M3 Pump Degradation Model) 60 -_ _ _ _ __ _ _ _
50 =
40 30 E 0 10 0 10 20 30 40 50 60 TIME (SECONDS)
GOTHIC 7.0 - FATHOMS COMPARISON ROTSG LARGE BREAK LOCA (14.1 ft2 Break -RV Outlet - High Initial RCS Flow w/ M3 Pump Degradation Model) 300 250-200 9 150-0 100 l l F~~~~~~~~~~~~~~athomsl 50 0 10 20 30 40 50 60 TIME (SECONDS)
GOTHIC 7.0 - FATHOMS COMPARISON ROTSG LARGE BREAK LOCA (14.1 ft2 Break - RV Outlet - High Initial RCS Flow w/ M3 Pump Degradation Model) 300-250 p200-f At'-'-
-- -I--- -- ' '~ ------ ~~~~~ - -- '----------------
3100- .
50-
- Fathoms
- -- Gohc70 0 . . . . .. . . . . . . . . . . . . . . .
0 20 40 60 80 100 120 140 160 180 TIME (SECONDS)
GOTHIC 7.0 - FATHOMS COMPARISON ROTSG LARGE BREAK LOCA (14.1 ft 2Break- RV Outlet - High Initial RCS Flow w/M3 Pump Degradation Model) 700000 600000 i 500000 Pa 400000 w
o0 300000 0 200000 100000 l~~ -~ - ~~~~~~~~~~~~~~~~~~~~~~
Gothics7 l 0 I I . . .I
. . . I.. . . . . .I. . . . .I . . . .I . . . . ...
0 20 40 60 80 100 120 140 160 180 TIME (SECONDS)
GOTHIC 7.0 - FATHOMS COMPARISON ROTSG LARGE BREAK LOCA (8.55 ft2 Break - Cold Leg Pump Discharge) 60 -_ _ _ _ _ _ _ _
50-
~40 130 20 10 0o . . . . . 60 0 10 20 30 40 50 60 TIME (SECONDS)
GOTHIC 7.0 - FATHOMS COMPARISON ROTSG LARGE BREAK LOCA (8.55 ft2 Break - Cold Leg Pump Discharge) 300-250 200 150
- 10 100 0 10 20 30 40 50 60 TIME (SECONDS)
GOTHIC 7.0 - FATHOMS COMPARISON ROTSG LARGE BREAK LOCA (8.55 ft2 Break - Cold Leg Pump Discharge) 300-250 I-~~~20 Iz100 50
-Fathoms
--- Gothic 7.0 0 20 40 60 80 100 120 140 TIME (SECONDS)
GOTHIC 7.0 - FATHOMS COMPARISON ROTSG LARGE BREAK LOCA (8.55 ft2 Break - Cold Leg Pump Discharge) 600000 500000 0 400000
~~9300000-
-4 0
+
A 200000-10oo0oo Fathoms
--Gothic 7.0 0 20 40 60 80 100 120 140 TIME (SECONDS)
GOTHIC 7.0 - FATHOMS COMPARISON ROTSG LARGE BREAK LOCA (8.55 ft Break - Cold Leg Pump Discharge) 60 -
50 40 20 -
10 0 10 2030400Fathoms 0 . . . . . . . .. . . .. . . .. . . .' ' .
0 10 20 30 40 50 60 TIME (SECONDS)
GOTHIC 7.0 - FATHOMS COMPARISON ROTSG LARGE BREAK LOCA (8.55 ft2 Break - Cold Leg Pump Suction) 3_ __ _ _
250 200 9 150-100 0 10 20 30 40 50 60 TIME (SECONDS)
GOTHIC 7.0 - FATHOMS COMPARISON ROTSG LARGE BREAK LOCA (8.55 ft2 Break - Cold Leg Pump Suction) 300 250 - - - - - - - - -
2200 150-~~~
Got ic----
150
- Fathoms
- -- Gothic 7.0 0 20 40 60 80 100 120 140 TIME (SECONDS)
GOTHIC 7.0 - FATHOMS COMPARISON ROTSG LARGE BREAK LOCA (8.55 ft2 Break - Cold Leg Pump Suction) 500000-450000 400000
, 350000 j 300000 0250000 200000 150000 100000
- -- Gothic 7.0 50000 0 20 40 60 . . . . . . . . . . . .140 0 20 40 60 80 100 120 140 TIME (SECONDS)
Questions On DPC-NE-3003-P and DPC-NE-3003-P Revision I Chapter 1
- 4. Page 1-2 of DPC-NE-3003-P: The last paragraph discusses the FATHOMS code. This should be modified to include discussion of the GOTHIC code.
Response: Revision 4 on p. 34 of Attachment 3 to the June 13, 2002 submittal includes a new sentence on p. 1-3 of the topical report that mentions the new Appendix C for the GOTHIC 7.0 code. This is the preferred text to include referral to the GOTHIC 7.0 content in Chapter 1 of the report. Also, Revision 10 on p. 3-6 includes more discussion of GOTHIC 7.0 in Chapter 2.
- 5. Page 1-3: (a) Why was NRC review of Supplement 1, the November 1997 version of DPC-NE-3003-P not required? (b) Please provide Supplement 2 of DPC-NE-3003-P.
Response: (a) Supplement 1 is a revised application of the NRC-approved methodology for the steam line break mass and energy release and containment response methodology. The main difference in the Supplement 1 application compared to the Chapters 5 & 6 application is crediting main feedwater isolation via the Main Steam Line Break Detection and Main Feedwater Isolation System. The Main Steam Line Break Detection and Main Feedwater Isolation System is a station modification that was installed subsequent to the submittal of the topical report. This station modification and associated analyses were reviewed and approved by the NRC by letter dated December 7, 1998 (License Amendments 234, 234, and 233). Supplement 1, the current UFSAR Chapter 6 analysis, was added since it replaced the analysis in Chapters 5 & 6 as the licensing basis analysis. The intent was to avoid future use of the superceded analysis results in Chapters 5 & 6. The Chapters 5 & 6 analyses were retained for historical purposes. No new methodology was included in Supplement 1, and so submittal for NRC review was not required.
(b) Supplement 2 of DPC-NE-3003-P is already included at the back of the November 1997 published version.
Chapter 3
- 6. Pages 3-9 and 3-10: Conservative mass and energy calculations depend not only on bounding high fuel stored energy but the rapid transfer of this energy to the coolant. Please describe the modeling of this energy transfer and why it is conservative.
Response: The gap thermal conductivity required to obtain the desired conservative initial fuel temperature is held constant during the peak containment pressure analysis. The time of peak containment pressure roughly corresponds with the end of the primary coolant system blowdown as the mass release is the primary driving factor for the containment pressure response.
During the blowdown the core average fuel temperature decreases from an initial value of approximately 13909F, to approximately 5909F. At the end of blowdown the volume average core fluid temperature is about 3 10F with an average vapor void fraction 1-62
exceeding 98%. With the current modeling approach, approximately three quarters of the core stored energy and all of the heat generated in the fuel is released during the primary coolant system blowdown. This modeling approach is conservative since the gap thermal conductivity is held constant. As the fuel cools during blowdown, the gap would actually open causing the gap thermal conductivity to decrease. This phenomenon is not credited in the methodology.
- 7. Page 3-13: (a) Please explain why the sump water temperature and the EQ temperatures are bounding for different break sizes. (b) It appears that the report is stating that a double-ended guillotine break at the same location (reactor vessel outlet nozzle) has two different values (8.55 ft2 and 14.1 ft2 ). Please clarify.
Response: The double-ended guillotine flow area for a cold leg pump discharge break is 8.55 ft2.
The double-ended guillotine flow area for a hot leg break is 14.1 ft2 . The cold leg pump discharge break is the limiting break location for the EQ response. A typographical error is included in this change. The sentence that includes the 8.55 ft2 flow area should have identified the break location as "reactorvessel inlet nozzle" instead of "reactorvessel outlet nozzle".
- 8. Page 3-15: Why was it necessary to change the RBS flow rate assumptions in the BWST depletion and the FATHOMS analysis to be consistent when they were previously conservative? What is the effect of this loss of conservatism in terms of peak containment pressure and temperature, and EQ temperatures?
Response: The original topical report text included specific flow values which are changing due to modifications being made to the reactor building spray headers. Specifically, some of the spray nozzles are being plugged and flow orifices are being installed to reduce the total spray flow. Previously RBS flow was manually throttled to a setpoint. The modifications described will eliminate the need for throttling. The spray values assumed in the analysis are conservative for the plant following the modifications.
There is no impact to the short-term LOCA peak containment pressure analysis as RBS operation is not credited. The assumed spray flowrates assumed in the long-term LOCA analysis and the steam line break analysis are conservative values. Use of conservative values for inputs to the methodology is considered appropriate. The reduction is spray flow is offset in the steam line break analysis that determines the EQ temperature profile by increasing the required capacity of the RBCUs (the fan coolers).
Chapter 4
- 9. Page 3-16: (a) Rather than using a simple containment model built into the RELAP5 calculation, input to RELAP5 from the FATHOMS code is used. (a) Is there a feedback to ensure consistency between the RELAP5 and the FATHOMS calculations? (b) The description of this phase of the calculation says that "similar break sizes" are used. What criteria are used to determine that the break sizes are "similar" and why do calculations from "similar" break sizes give results that are better than those from a simple model of (presumably) the same break size? (c) Provide results from sensitivity calculations to 1-63
demonstrate that the start times for the RBCUs and the RBS are close enough to each other and that the containment peak conditions are acceptably close.
Response: (a) There is no feedback between the FATHOMS and RELAP5 calculations.
However, it should be noted that for all SBLOCA cases the break remains choked and therefore the containment pressure does not directly impact the RELAP5 calculation.
There are two FATHOMS results that do impact the RELAP5 calculation 1) the RBS actuation time (actuates on high containment pressure), which effects the timing of the swap to sump recirculation and 2) the containment sump water temperature, which affects the injection water temperature during sump recirculation. Iterations are performed until the results converge or conservative agreement is achieved between the FATHOMS calculation and the RELAP5 assumptions. These parameters are compared in the answer to item (c) below.
(b) The wording in the technical justification could be modified to be more precise. For all of the cases that were reanalyzed for the ROTSG, the FATHOMS results used in each of the RELAP5 calculations were taken from the cases with the same size break. In general a larger break could be used as a conservative boundary condition for a smaller break since spray actuation will occur earlier and the sump temperature will generally be hotter. The wording should have stated "for a similar case" instead of "for a similar break size" since there are other assumption in the FATHOMS analysis (i.e. RBCU performance, cooling water temperature, initial conditions) which can impact the containment results.
(c) The RBCUs are not modeled in the RELAP5 calculation. The same RBS actuation time is assumed in the RELAP5 and the FATHOMS calculations. The assumed actuation time was determined from preliminary calculations. In the final FATHOMS calculation, a check is made of the predicted FATHOMS containment pressure at RBS actuation and the analysis setpoint (20 psig). The assumed actuation times and the FATHOMS calculated pressures at the time of RBS actuation are provided in Table 9-1. The containment sump water temperatures calculated by FATHOMS and assumed in the RELAP5 calculation are also provided in Table 9-1.
Table 9-1 Comparison of FATHOMS calculated parameters with the RELAP5 assumptions Parameter 0.01 Break Size 0rmtr01 fW 0.025 ftz 0.05 fL RBCU actuation - FATHOMS 1895 sec 898 sec 573 sec RBCU actuation - RELAP5 not modeled not modeled not modeled RBS actuation - FATHOMS 9000 sec 4000 sec 1200 sec RBS actuation - RELAP5 (for BWST depletion only) 9000 sec 4000 sec 1200 sec FATHOMS calculated containment pressure at RBS actuation 21 psig 25 psig 22 psig FATHOMS calculated sump temperature
- At start of sump recirculation 184 °F 190 °F 200 °F
- Peak 201 F 200 F 215 F RELAP5 assumed sump water temperature recirculation
- At start of sump recirculation 185 °F 200 °F phase not
- Peak 205 °F 200 OF modeled 1-64
- 10. Page 3-16 to 3-17: In the transition from RELAP5 to FATHOMS for small break calculations the heat structures will be modeled as heaters with a prescribed heat flux. They were previously modeled as heat slabs. (a) What is the advantage of this change? (b) How is the heat flux of the heater component determined as a function of time? (c) Provide a sensitivity study of the effect of the heat flux vs. heat structure on the long- term containment response.
Response: The original version of DPC-NE-3003-PA contained a discrepancy between the RELAP5 and FATHOMS treatments of the primary and secondary system fluid and metal energy content and the manner in which it was passed from RELAP5 to FATHOMS. In Section 4.1, Long-Term Mass and Energy Release, first paragraph on p.4-3, the original documentation discussed the RELAP5 heat structures being collapsed into heat slabs consistent with the simplified FATHOMS node boundaries. In Section 6A.3, pg. 6-31, the original documentation stated that the RCS heat structures are modeled with the FATHOMS heater model. The changes to Section 4.1 of DPC-NE-3003 were made to remove this discrepancy in the documentation, and represent no changes to the mass and energy release or containment response methodology.
The technical justification to Change #35 in the DPC-NE-3003, Revision 1 change package incorrectly stated that there was a change in the stored energy modeling for the FATHOMS small break LOCA containment analyses. The FATHOMS heater component model has always been used for the small beak LOCA analyses; there were no changes to this methodology introduced, other than the inclusion of the stored energy in the secondary system fluid and structural metal (which had been left out in the original analyses). The final sentence in the Technical Justification to Change #35 also incorrectly discusses the impact of a modeling change from the heat slab to heater component model in the FATHOMS small break LOCA analyses.
In summary, there was no change to the methodology used to transfer the energy from the primary and secondary system fluid/metal from the RELAP5 to the FATHOMS small break LOCA analyses (other than the inclusion of the secondary system energy content).
The discussion in the Technical Justification to Change #35 regarding such a change was in error. The heat flux is calculated by dividing the total energy content of each component at the end of the RELAP5 analysis by the remaining transient time in the FATHOMS analysis (a constant heat flux is assumed for each component for the duration of the FATHOMS analysis).
- 11. Section 6.1 Page 6-1 of DPC-NE-3003-P: Some words are missing between the last sentence on page 6-1 and the first words on page 6-2 of the original report. The proposed revision did not fix this. Please provide the missing words.
Response: The November 1997 version added the missing paragraph to the bottom of p. 6-1.
- 12. Section 6.2.1 Page 6-9 First paragraph: If Case 3B is considered the worst case LOCA for containment peak pressure, isn't the loss of offsite power, rather than loss of a 4160-V bus, the more limiting case? Please explain.
Response: The with or without offsite power assumption, as discussed on pp. 3-2 and 3-21, is mainly of interest for the LOCA peak pressure analyses relative to the continued 1-65
operation of the reactor coolant pumps. Both with offsite power (RCPs continue to run) and without offsite power (RCPs trip at time zero) cases are analyzed. The limiting single failure assumption, as discussed beginning on p. 3-12, involves the loss of emergency power to a 4160V bus, which causes a loss of one train of safeguards. This single failure is irrelevant for the peak pressure cases since the peak containment pressure is reached prior to the actuation of any of the safeguards powered by the 4160V bus regardless of whether or not the single failure is assumed. The loss of offsite power assumption has only a minor impact on the peak pressure results as discussed in the first paragraph on p. 6-9.
Questions Concerning GOTHIC
- 13. Provide a temperature envelope curve for EQ purposes calculated with GOTHIC and with FATHOMS. Discuss the differences in EQ envelopes calculated with FATHOMS and GOTHIC due to the use of different models in the two codes, especially those models which affect moisture in the atmosphere.
Response: To be provided at a later date.
- 14. Show that GOTHIC and FATHOMS calculations result in the same pressures, temperatures, sump temperatures, etc. for the design basis LOCA and main steam line break events. If they do not, explain differences in terms of the differences in models between the two codes. (See Question 1.)
Response: Refer to the response to Question #3 for LOCA. The results of the 6 code comparison analyses for the main steam line break are given in Table 14-1 and the figures that follow.
The containment response following a main steam line break event for the ROTSG was performed to compare the results from FATHOMS 2.4 and GOTHIC 7.0. In general, the pressure and vapor temperature responses are very similar. GOTHIC 7.0 predictions for peak pressures are slightly lower on the smaller break sizes (0.3 psi) and slightly higher for larger break sizes (0.95 psi). The peak vapor temperature responses predicted by GOTHIC 7.0 overall are slightly lower (-120 F). For larger break sizes, the higher pressure predicted by GOTHIC 7.0 may be attributed to additional steam generation from the improved interface heat and mass transfer models and from the drops that are generated due to dripping. The slightly lower pressure for smaller break sizes may be attributed to additional droplets in the atmosphere. The slightly lower vapor temperature and liquid temperature in GOTHIC 7.0 for all break sizes may be attributed to additional droplets in the atmosphere also. This effectively increases the heat capacity of the atmosphere and reduces the temperature rise for a given energy addition. As discussed in the responses to Questions #1 and #3, more liquid is predicted to remain in droplet form in GOTHIC 7.0 which results in less liquid mass in the sump. In addition, the lower sump temperature predicted by GOTHIC 7.0 may be attributed to the addition of the second energy equation for the drops and the improved heat and mass transfer models in GOTHIC 7.0.
1-66
Table 14-1 Peak Containment Peak Containment Pressure (psig) Temperature (F)
ROTSG Case Description Fathoms Gothic 7.0 Fathoms Gothic 7.0 0.2 ft2 Steam Line Break 42.48 42.48 311.38 301.04 0.6 ft2 Steam Line Break 54.76 54.53 384.69 372.05 1.0 ft2 Steam Line Break 56.60 56.32 417.82 405.07 1.0 ft2 Steam Line Break with 90" 43.57 43.74 417.23 404.63 SG Level 1.4 ft2 Steam Line Break 52.23 53.18 438.80 426.02 Double Ended Guillotine Steam 55.23 55.63 463.08 450.11 Line Break 1-67
GOTHIC 7.0 - FATHOMS COMPARISON ROTSG STEAM LINE BREAK (0.2 f 2 Break) 45 40 35 t 30 25 00 .~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ I l 20 10 15 0
5 I/ Aothic 7.0 0
0 200 400 600 800 1000 1200 TIME (SECONDS)
GOTHIC 7.0 - FATHOMS COMPARISON ROTSG STEAM LINE BREAK (0.2 ft2 Break) 350 300 L 250 Ed4 t 200
- 150 100
. l ~~~~~~~~~~~~~~~~~~~~~~
l- -- Gothic 7.0 50 . . ..... . . . . . . . . . . . . . . ...
0 200 400 600 800 1000 1200 TIME (SECONDS)
GOTHIC 7.0 - FATHOMS COMPARISON ROTSG STEAM LINE BREAK (0.2 f 2 Break) 250 200 0~~~~
~10 00' 50
[- - - Gohic 7.0
- 0. .20040
.0 . 0 .0 .0 .0 .
0 200 400 600 800 1000 1200 TIME (SECONDS)
GOTHIC 7.0 - FATHOMS COMPARISON ROTSG STEAM LINE BREAK (0.2 ft Break) 200000 180000-160000 140000 120000-8
_ 100000-/,
g 80000__ _ _ __ _
60000-40000 20000 Fathoms
/~~~~~~~~~~~~~~~~ __- Gothici 7.0 0-0 200 400 600 800 1000 1200 TIME (SECONDS)
GOTHIC 7.0 - FATHOMS COMPARISON ROTSG STEAM LINE BREAK (0.6 ft2 Break) 130
~20-0 10 0 100 200 300 400 500 600 700 800 900 TIME (SECONDS)
GOTHIC 7.0 - FATHOMS COMPARISON ROTSG STEAM LINE BREAK (0.6 ft 2 Break) 450 __ =X 400-350 300-w ~250-0 200 150 100 -Fathoms
- -- Gothic 7.0 50o.
0 100 200 300 400 500 600 700 800 900 TIME (SECONDS)
GOTHIC 7.0 - FATHOMS COMPARISON ROTSG STEAM LINE BREAK (0.6 ft Break) 250 200-
~100 50-
-Fathoms
- -- Gothic 7.0 0 . . . . 0 3 . . . .4 5 . . . . . . .
0 100 200 300 400 500 600 700 800 900 TIME (SECONDS)
GOTHIC 7.0 - FATHOMS COMPARISON ROTSG STEAM LINE BREAK (0.6 ft2 Break) 120000-100000 80000-400 10-0 0 0 0 0 0 0 0
/ ,,.,< I_~~~-Fathomsl lo .... .. .... . _w~~~~~~~~~~~~~e-- _-'...... l-Gothic7.0 0 loo 200 300 400 So0 600 700 800 900 TIME (SECONDS)
GOTHIC 7.0 - FATHOMS COMPARISON ROTSG STEAM LINE BREAK (1.0 ft Break) 60-50-
~40-
~30
~20-0 10 /
23000Fathoms
- -- Gothic 7.0 0 100 200 300 400 500 600 700 TIME (SECONDS)
GOTHIC 7.0 - FATHOMS COMPARISON ROTSG STEAM LINE BREAK (1.0 ft2 Break) 450-350 4 00 ~ ------
300 l250 l 2200-150 -
100- - Fathoms
--- Gothic 7.0 50 . . . . . . . . . . . . . . . .
0 100 200 300 400 500 600 700 TIME (SECONDS)
GOTHIC 7.0 - FATHOMS COMPARISON ROTSG STEAM LINE BREAK (1.0 f 2 Break) 250-200 - -------
7 150 00
~100 50-
- Fathomns
- -- Gothic 7.0 0 100 200 300 400 500 600 700 TIME (SECONDS)
GOTHIC 7.0 - FATHOMS COMPARISON ROTSG STEAM LINE BREAK (1.0 f 2 Break) 70000 60000-50000-t: 40000-
~30000 0'~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~J 20000 -
co 10000 0 --
-Fathoms
- -- Gothic 7.0 0
0 100 200 300 400 500 600 700 TIME (SECONDS)
GOTHIC 7.0 - FATHOMS COMPARISON ROTSG STEAM LINE BREAK (1.0 ft Break with SG Level Controlled to 90")
60 50 420 00~
10
-Fathoms
- - - Gothic 7.0 0 100 200 300 400 500 600 700 TIME (SECONDS)
GOTHIC 7.0 - FATHOMS COMPARISON ROTSG STEAM LINE BREAK 2
(1.0 ft Break with SG Level Controlled to 90")
450 350-00 00 ____300_
~250-150-100 - Fathoms
--- Gothic 7.0 50 . . . . . . . . . . . . . . .
0 100 200 300 400 500 600 700 TIME (SECONDS)
GOTHIC 7.0 - FATHOMS COMPARISON ROTSG STEAM LINE BREAK (1.0 ft2 Break with SG Level Controlled to 90")
250-200 -- --
150 - _ _ __ _ _ _ _ _ _
00 g100 -
50-S
.Fathoms
-- Gothic 70 0 . . . . . . . .. . . .4.0. . . . . . . I 0 100 200 300 400 500 600 700 TIME (SECONDS)
GOTHIC 7.0 - FATHOMS COMPARISON ROTSG STEAM LINE BREAK (1.0 ft Break with SG Level Controlled to 90")
70000 -
60000 50000
^ 40000
- 30000-/
co 20000 10000 - Fthm
- -- Gothic 7.0 O .... 200 . . .. 40 700 O 100 200 300 400 500 600 700 TIME (SECONDS)
GOTHIC 7.0- FATHOMS COMPARISON ROTSG STEAM LINE BREAK (1.4 f 2 Break) 60 50-s40 30 z20 .
10 /
Fathoms
--- Gothic 7.0 0 50 100 150 200 250 300 350 400 TIME (SECONDS)
GOTHIC 7.0 - FATHOMS COMPARISON ROTSG STEAM LINE BREAK (1.4 ft2 Break) 500 450 350-300-4200 PQ 250
.. 200 -_ _ _ _
150 100 -Fathoms
--- Gothic 7.0 50 510. .0 .150200250
.300.34 .0 0 50 100 150 200 250 300 350 400 TIME (SECONDS)
GOTHIC 7.0 - FATHOMS COMPARISON ROTSG STEAM LINE BREAK (1.4 ft Break) 250 -_ _ _ _ _
200 15 0 O
~100 50
-Fathoms
- -- Gothic 7.0 0 50 100 150 200 250 300 350 400 TIME (SECONDS)
GOTHIC 7.0 - FATHOMS COMPARISON ROTSG STEAM LINE BREAK (1.4 f 2 Break) 10000 9000 8000-7000
~6000 5000 0'4000 3000 2000 1000 Fathoms
--- Gothic 7.0 0
0 50 100 150 200 250 300 350 400 TIME (SECONDS)
GOTHIC 7.0 - FATHOMS COMPARISON ROTSG STEAM LINE BREAK (Double-Ended Guillotine Break) 60 50 00 30_ _ _ __ _ _ _
20 10
-Fathoms
--- Gothic 7.0 0 -
0 20 40 60 80 100 120 140 160 180 200 TIME (SECONDS)
GOTHIC 7.0 - FATHOMS COMPARISON ROTSG STEAM LINE BREAK (Double-Ended Guillotine Break) 500 -_ _ _ _ _ _
450 400-IZ 350-300 250-
~200 150 100 FaXom 0 20 40 60 80 100 120 140 160 180 200 TIME (SECONDS)
GOTHIC 7.0 - FATHOMS COMPARISON ROTSG STEAM LINE BREAK (Double-Ended Guillotine Break) 250-200 150 -
10 50-Fathoms
-- Gothic 7.0 0 20 40 60 80 100 120 140 160 180 200 TIME (SECONDS)
GOTHIC 7.0 - FATHOMS COMPARISON ROTSG STEAM LINE BREAK (Double-Ended Guillotine Break) 300-250 200-
` 150 co 100 50 Fathoms
- - - Gothic 7.0 0 ---- 40 60-80-100-120-140 160180200 0 20 40 60 80 100 120 140 160 180 200 TIME (SECONDS)
- 15. Will the Mist Diffusion Layer (MDL) model be used in GOTHIC calculations? If so, please provide curves of a main steam line break calculation with and without this model. All other input and assumptions should be as proposed for licensing basis calculations.
Response: The Uchida Condensation Option will be utilized for all heat slabs in the GOTHIC calculations. This is consistent with the guidance in ANSI/ANS 56.4-1983. This represents no change in the containment analysis methodology (consistent with FATHOMS).
- 16. Will GOTHIC calculations be performed with a pressure flash or temperature flash assumption concerning the distribution of vapor in the containment atmosphere?
Response: The GOTHIC boundary conditions representing LOCA mass and energy releases will partition the flow by phase. Separate flowrates and enthalpies for the steam and liquid phases of the blowdown are calculated in the RELAP5 code and passed to GOTHIC as separate boundary conditions. All liquid flow is entered as droplets when the RCS pressure exceeds the containment pressures. Subsequently the distribution of the droplets is determined by GOTHIC's heat and mass transfer equations. When the RCS pressure has decreased to the containment pressure the liquid flow is entered in the continuous liquid phase, and spills onto the containment floor with little energy transfer. This liquid phase will not flash into steam, as is permitted in the 'pressure flash' model from CONTEMP14. The steam phase break flow from the RELAP5 blowdown analysis is added directly to the containment atmosphere.
For main steam line break mass and energy releases, the boundary condition is single phase steam, and so the question is not applicable.
- 17. Will the Drop Liquid Conversion Option be used in GOTHIC calculations? If so, please provide curves of a 14.1 ft2 hot leg beak at the vessel outlet calculation with and without this model. All other input and assumptions should be as proposed for licensing basis calculations.
Response: The Drop Liquid Conversion Option, which signals the use of the GOTHIC default models for drop phase entrainment, agglomeration, and deposition, will be used in the GOTHIC calculations. This is consistent with the selection of code-calculated de-entrainment fractions, rather than a user-specified value, in previous FATHOMS analyses.
When the 14.1 ft2 hot leg break at the vessel outlet from the set of GOTHIC runs in response to Question #3 above is re-run with the Drop Liquid Conversion Option set to IGNORE, the GOTHIC peak pressure calculation is identical to the original case with the INCLUDE option. The selection of this option has no impact on the calculated peak pressure. Since the results with this option removed are identical to the base case, no curve is provided.
1-92
ATTACHMENT 2 ADDITIONAL REVISIONS TO DPC-NE-3003, REVISION 1 "Mass and Energy Release and Containment Response Methodology"
Attachment 2 Additional Revisions To DPC-NE3003, Revision 1 "Mass and Energy Release and Containment Response Methodology" The following two items are additional revisions that were not included in the scope of the original Revision 1 submitted for NRC review by letter dated June 13, 2002.
- 1. Appendix C, "GOTHIC Version 7.0 Code", of Revision 1 of DPC-NE-3003 (Attachments 3 &
4 of the June 13, 2002 submittal) describes Duke's proposed use of the GOTHIC 7.0 code for the containment response analysis. The following paragraph is from pp. 3-62 and 4-62 of Attachments 3 and 4, respectively.
"GOTHIC 7.0features the use of control variables that are not availablein FATHOMS.
The control variablesprovide enhanced capabilityandflexibility to input boundary conditions orforcingfunctions into the code. Forinstance, the output of the BFLOW code to determine the quality of water exiting a cold leg breakfor long-term mass and energy releasescan be input via control variables. This capabilitywas not availablefor FATHOMS and specific code changes were implemented in order to input the BFLOW code results (Section 2.4.1.2). "
Subsequent to the submittal of Revision 1,Duke has decided not to use the GOTHIC 7.0 control variables for input of the output of the BFLOW code. Rather, GOTHIC 7.0 has been modified similar to the modifications previously made to FATHOMS to input the results of the BFLOW methodology. Therefore, the GOTHIC 7.0 and FATHOMS methodology will be the same with regard to how the results of BLOW are input. The above paragraph will be revised as follows to indicate this similarity:
"GOTHIC 7.0featuresthe use of control variables that are not availablein FATHOMS.
The control variablesprovide enhancedcapability andflexibility to input boundary conditions orforcingfunctionsinto the code. These are essentially user convenience features and do not constitute elements of the methodology.
The long-term mass and energy releaseboundary condition modeling in FATHOMS has been similarly installedin GOTHIC 7.0. This modeling approach,which enables interpolationof the BFLOW code results as an input boundary condition, are described in Sections 2.21.1, 2.4.1.2, and 6.3 of DPC-NE-3003."
- 2. Due to the code modification to GOTHIC Version 7.0 described in Item #1 above, the code version must be uniquely identified. This Duke-specific version will be designated GOTHIC 7.0/DUKE in the published version of the report.
2-1