ML20148C704
| ML20148C704 | |
| Person / Time | |
|---|---|
| Site: | 05200003 |
| Issue date: | 05/20/1997 |
| From: | Mcintyre B WESTINGHOUSE ELECTRIC COMPANY, DIV OF CBS CORP. |
| To: | Quay T NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| Shared Package | |
| ML19355F196 | List: |
| References | |
| AW-97-1111, NUDOCS 9705280210 | |
| Download: ML20148C704 (34) | |
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Westinghouse Energy Systems sa 355 Electric Corporation Pittsburgh Pennsylvania 15230-0355 AW-97-1111 May 20,1997 Document Control Desk U.S. Nuclear Regulatory Commission Washington, D.C. 20555 ATTENTION:
MR. T. R. QUAY APPLICATION FOR WITHHOLDING PROPRIETARY INFORMATION FROM PUBLIC DISCLOSURE
SUBJECT:
WESTINGHOUSE RESPONSES TO NRC REQUESTS FOR ADDITIONAL INFORMATION ON THE AP600
Dear Mr. Quay:
The application for withholding is submitted by Westinghouse Electric Corporation (" Westinghouse")
pursuant to the provisions of paragraph (b)(1) of Section 2.790 of the Commission's regulations. It contains commercial strategic information proprietary to Westinghouse and customarily held in confidence.
The proprietary material for which withholding is being requested is identified in the proprietary version of the subject report, in conformance with 10CFR Section 2.790, Affidavit AW-97-1111 accompanies this application for withholding setting forth the basis on which the identified proprietary l
information may be withheld from public disclosure.
Accordingly, it is respectfully requested that the subject information which is proprietary to Westinghouse be withheld from public disclosure in accordance with 10CFR Section 2.790 of the Commission's regulations.
Correspondence with respect to this application for withholding or the accompanying affidavit should l
reference AW-97-1111 and should be addressed to the undersigned.
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Very truly yours, l
l An /# %
i Brian A. McIntyre, Manager Advanced Plant Safety and Licensing jml
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cc:
Kevin Bohrer NRC OWFN - MS 12E20 9705280210 970020 PDR ADOCK 05200003 A
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COMMONWEALTH OF PENNSYLVANIA:
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l COUNTY OF ALLEGIIENY:
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Before me, the undersigned authority, personally appeared Brian A. McIntyre, who, being by l
me duly sworn according to law, deposes and says that he is authorized to execute this Affidavit on i
l.
behalf of Westinghouse Electric Corporation (" Westinghouse") and that the averments of fact set forth in this Affidavit are true atid correct to the best of his knowledge, information, and belief:
6A Jp<
i d2 y -
I Brian A. McIntyre, Manager Advanced Plant Safety and Licensing.
Sworn to and subscribed before me this Jfg day of
,1997 g
Notanal Seal I
Janet A. Schwab, Notary P&
Monroeville Boro, A!!egheny My Commission Expires May 22. _
Memter, Pennsytvania Association of Notarle~s 7
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5 AW-97-1111 (1)
I am Manager, Advanced Plant Safety.And Licensing, in the Advanced Technology Business Area, of the Westinghouse Electric Corporation and as such, I have been specifically delegated the function of reviewing the proprietary information sought to be withheld from public disclosure in connection with nuclear power plant licensing and rulemaking proceedings, and am authorized to apply for its withholding on behalf of the Westinghouse Energy Systems Business Unit.
1 (2)
I am making this Affidavit in conformance with the provisions of 10CFR Section 2.790 of the Commission's regulations and in conjunction with the Westinghouse application for withholding accompanying this Affidavit.
(3)
I have personal knowledge of the criteria and procedures utilized by the Westinghouse Energy Systems Business Unit in designating information as a trade secret, privileged or as confidential commercial or financial information.
(4)
Pursuant to the provisions of paragraph (b)(4) of Section 2.790 of the Commission's regulations, the following is furnished for consideration by the Commission in determining whether the information sought to be withheld from public disclosure should be withheld.
l (i)
The information sought to be withheld from public disclosure is owned and has been held in confidence by Westinghouse.
(ii)
The information is of a type customarily held in confidence by Westinghouse and not customarily disclosed to the public. Westinghouse has a rational basis for determining the types of information customarily held in confidence by it and, in that connection, utilizes a system to determine when and whether to hold certain types of information in confidence. The application of that system and the substance of that system constitutes Westinghouse policy and provides the rational basis required.
Under that system, information is held in confidence if it falls in one or more of several types, the release of which might result in the loss of an existing or potential competitive advantage, as follows:
l mu
5 AW-97-1111 s
(a)
The information reveals the distinguishing aspects of a prmess (or component, structure, tool, method, etc.) where prevention of its use by any of Westinghouse's competitors without license from Westinghouse constitutes a competitive economic advantage over other companies.
(b)
It consists of supporting data, including test data, relative to a process (or component, structure, tool, method, etc.), the application of which data secures a competitive economic advantage, e.g., by optimization or improved marketability.
(c)
Its use by a competitor would reduce his expenditure of resources or improve his competitive position in the design, manufacture, shipment, installation, assurance of quality, or licensing a similar product.
(d)
It reveals cost or price infonnation, production capacities, budget levels, or commercial strategies of Westinghouse, its customers or suppliers.
(e)
It reveals aspects of past, present, or future Westinghouse or customer funded development plans and programs of potential commercial value to Westinghouse.
(f)
It contains patentable ideas, for which patent protection may be desirable.
There are sound policy reasons behind the Westinghouse system which include the following:
(a)
The use of such information by Westinghouse gives Westinghouse a competitive advantage over its competitors. It is, therefore, withheld frorn disclosure to protect the Westinghouse competitive position.
(
(b)
It is information which is marketable in many ways. The extent to which such information is available to competitors dimittishes the Westinghouse ability to i
sell products and services involving the use of the information.
3214A
2 AW-97-1111 l
(c)
Use by our competitor would put Westinghouse at a competitive disadvantage by reducing his expenditure of resources at our expense.
l 1
(d)
Each component of proprietary information pertinent to a particular competitive advantage is potentially as valuable as the total competitive advantage. If competitors acquire components of proprietary information, any one component may be the key to the entire puzzle, thereby depriving Westinghouse of a competitive advantage.
(e)
Unrestricted disclosure would jeopardize the position of prominence of Westinghouse in the world market, and thereby give a market advantage to the competition of those countries.
(f)
The Westinghouse capacity to invest corporate assets in research and development depends upon the success in obtaining and maintaining a competitive advantage.
(iii)
The information is being transmitted to the Commission in confidence and, under the provisions of 10CFR Section 2.790, it is to be received in confidence by the Commission.
(iv)
The information sought to be protected is not available in public sources or available information has not been previously employed in the same original manner or method to the best of our knowledge and belief.
(v)
Enclosed is Letter NSD-NRC-97-5141, May 20,1997 being transmitted by Westinghouse Electric Corporation (W) letter and Application for Withholding Proprietary Information from Public Disclosure, Brian A. McIntyre (W), to i
Mr. T. R. Quay, Office of NRR. The proprietary information as submitted for use by t
Westinghouse Electric Corporation is in response to questions concerning the AP600 i
plant and the associated design certification application and is expected to be applicable in other licensee submittals in response to certain NRC requirements for i
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AW-97-Illi justification of licensing advanced nuclear power plant designs.
l This information is part of that which will enable Westinghouse to:
)
i l
(a)
Demonstrate the design and safety of the AP600 Passive Safety Systems.
(b)
Establish applicable verification testing methods.
(c)
Design Advanced Nuclear Power Plants that meet NRC requirements.
(d)
Establish technical and licensing approaches for the AP600 that will ultimately result in a certified design.
(e)
Assist customers in obtaining NRC approval for future plants.
Further this information has substantial commercial value as follows:
1 (a)
Westinghouse plans to sell the use of similar information to its customers for purposes of meeting NRC requirements for advanced plant licenses.
(b)
Westinghouse can sell support and defense of the technology to its customers in the licensing process.
i Public disclosure of this proprietary information is likely to cause substantial harm to the competitive position of Westinghouse because it would enhance the ability of competitors to provide similar advanced nuclear power designs and 'icensing defense services for commercial power reactors without commensurate expenses. Also, public l
disclosure of the information would et.able others to use the information to meet NRC i
requirements for licensing documentation without purchasing the right to use the information.
N i
22 H A j
f AW-97-1111 i
The development of the technology described in part by the information is the result of applying the results of many years of experience in an intensive Westinghouse effort and the expenditure of a considerable sum of money.
In order for competitors of Westinghouse to duplicate this information, similar technical programs would have to be performed and a significant manpower effort, j
having the requisite talent and experience, would have to be expended for developing analytical methods and receiving NRC approval for those methods.
Further the deponent sayeth not.
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ENCLOSURE 2 TO WESTINGHOUSE LETTER NSD-NRC-97-5141 NON-PROPRIETARY I
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e NRC REQUEST FOR ADDITIONAL INFORMATION RAI 440.589 l
The trends in the WCOBRA/ TRAC analyses of the OSU SB01 test show an overprediction ofinjection l
flow and an underprediction of exit flow. Extrapolation of these trends wouldlead to a conclusion that the calculated reactor vessel water level willnot fit the test data wellbeyond the end of the window.
Specifically, Figures 5.1-3 to 5.1-10 show that the injection flow rate is higher than the corresponding measured value.
Figures 5.111 and 6.1-12 indicate that the injected water temperature is considerably lower. Figures S. I 16 and S.1-18 indicate that ADS 123 and ADS 4-1 flows ora lower.
llthese trends continue, the calculated totalinjected water would be much greater than the test data shows and the calculated total boiloff and water exiting the RCS would be much less than the test data. This would result in an erroneously high value for the calculated reactor vessel water level sometime beyond the end of the window. Westin;%ouse shouldconsider extending the window width (by 3 to 4 times the current length of 1000 seconds) to demonstrate that the eventual trend stabilizes and balances with the final vessel water level consistent with the test data.
Response
As provided in Ref. 440.5891 and discussed in the ACRS meeting on March 28,1997, Westinghouse has performed several calculations of 3000 seconds in length which indicate no solution divergence.
in each of the cases, comparisons with the OSU test data were as favorable at 3000 seconds as at the end of the original 1000 second window and for the Extended Time Sensitivity, the results at the end of 3000 seconds of calculation time were shown to be identical to calculations started 2000 seconds later and run for 1000 seconds. In addition, Figure 440.589 1 was presented at the ACRS meeting which demonstrates that total WCIT vesselinflow equals total vessel outflow for the OSU test comparison cases once the quasi-equilibrium solution has been reached.
It was noted at the ACRS meeting that the reactor vessel collapsed levels are systematically low ( the conservative direction). Two factors contribute to this bias. First, as discussed in the WCOBRA/ TRAC Code Qualification Document (WCfT COD), WC/T tends to over predict liquid entrainment in the large break scenario. The equivalent effect in the Long Term Cooling (LTC) scenario is to carry out liquid from the upper plenum too easily and thus reduce the collapsed liquid level to a value below that observed in the tests. A second factor which contributes to the under predicted liquid level is the coarse noding in the top of the core and the bottom of the upper plenum, see Figure 2-2 in Ref.
440.589 2. To evaluate the impact of this noding, the Section 3 channels in the upper plenum, which were previously one cell high, were divided into three vertical cells. A set of calculatic w are performed for OSU Test SB01, during sump operation, in the time period from 18,000 secs:4, to 19,000 seconds. The comparison of the upper plenum levels and downcomer levels is attached in Figures 440.589 2 through 440.589 5. The upper plenum level is shown to be increased by 0.5 to 0.6 inches with the finer noding. Similiar results are observed in the hot leg levels. The increased number of vertical cells has a less significant effect on the downcomer level. While this does not show a major effect on the vessel levels, it does show the trend. It is noted that, the coarse noding was retained in the core (two vertical cds) and the radial noding in the upper plenum was not altered.
Thus, additional improvements in level calculations are expected if a more detailed noding is used.
440.589 1 i
l 3 W8stiligh0080 l
,a NRC REQUEST FOR ADDITIONAL INFORMATION l
As was discussed at the ACRS meeting, the WC/T comparison with SB01 was the least accurate of the comparisons in Ref. 440.5891 and Ref. 440.589 2. There are several factors which contribute to the differences in this comparison,if the uncertainities in the measured flow rates are not considered for the moment. First as shown in Table 440.5891 line 4, the WC/T calculated total ADS flow rams are in good agreement with the total OSU measured ADS flow rates, even though the agreement between the respective ADS 41 and ADS 4 2 is less accurate. However, as previously reported, the total DVI flow rates, line 7, do not compare favorably with 1.09 lb/sec calculated by WC/T versus 0.86 lb/sec measured at OSU. The divergence between the calculated and measured DVI flows from the IRWST lines, Figures 5.13 and 5.14, is more pronounced as indicated in Table 440.5891 lines 10 and 14. The major source of this discrepancy can be seen with a re-scaled plot of the break flows, see Figure 440.189 6 and 440.189-7, which indicate significant increases in the measured break flow at 14,500 seconds, if the measured break flows are accepted as correct, the total vesselinflows are in good agreement as shown on line 9 of Table 440.589 1. However, this implies that the WC/T calculated break flow rate is significantly under predicted, Table 440.589-1 line 8. Thus, the over prediction of the IRWST flows into the DVIlines is offset by an under prediction of break flow. This discrepancy is considered to be partially the result of measurement uncertainities on the DVIline flow rates. For example, the measured DVI flows from the IRWST are 0.17 lb/sec and 0.215 lb/see with a 2cr uncertainity on each of i 0.076 lb/sec. Thus, the flow rates measurements are have uncertainities of i 45% and i 35% respectively. Of more importance is the fact that the magnetic flowmeters, used for the liquid portion of the break flow, were not calibrated fur reverse flow (into the vessel) and are only useful for showing trends. Thus, the data uncertainty clouds the conclusions which can be drawn from this specific test comparion and leads to the conclusion that the entire set of comparisons must be viewed together if valid conclusions are to be drawn.
In conclusion, the 1g131 vessel inflows and 191jl} vessel outflows, lines 4 and 9 in Table 440.589-1 bs!ance quite well for both the WC/T calculation and the OSU test. Note, that all the individual values were checked when it was found that the measured break flow was mis-estimated due to poor scaling of the integrated breakflow plot, Figure 5.1.14. The component flows do not compare as well and this is considered to be primarily the result of the uncertainties in the measured flow rates. The argument that the calculations are not primarily at fault lies with the accuracy of the remaining comparisons.
This is demonstrated in Figures 440.589-8 through 440.58911 taken from the ACRS presentation.
References 440.589 1.
NSO/NRC-97-5014, 'WCOBRAfrRAC Long Term Cooling Letter Report", D.C. Garner, March 10,1997.
440.589-2. WCAP 14776, "WCOBRA/ TRAC OSU Long-Term Cooling Final Verification Report *, D.C.
Garner, et. al., November 1996.
Report Revision:
None 440.589 2 1
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NRC REQUEST FOR ADDITIONAL INFORMATION Table 440.5891 SB-01 Quasi-Equilibrium Flow Rates During Period from 14,500 to 15,000 Seconds Line WC/T Calculated OSU Measured No.
Flow (bm/sec)
Flow (bm/sec)
Vessel Outflows (a.b,c) 1.
ADS 1, 2, 3 0.005 2.
ADS 41 0.463 3.
ADS 4 2 0.729 4.
Total Outflow (1 +2+3) 1.197 Vessel Inflows 5.
Total DVI 1 0.535 6.
Total DVI 2 0.555 7.
Total DVI (5 + 6) 1.090 8.
2' Break Flow (into vessel) 0.070 9.
Totalinflow (5+6+8) 1.160 DVI Line Component Flows 10.
IRWST/DVl 1 0.370 11.
Sump /DVl-1 0.165 12.
CMT 1/DVI 1 0.000 13.
Total DVI-1 (10+11+12) 0.535 14.
IRWST/DVl 2 0.290 "
15.
Sump /DVl-2 0.165 16.
CMT 2OVI-2 0.100 "
17.
Total DVl 2 (14+15+16) 0.555 Figure 5.14 includes 0.100 bm/see from CMT 2 with IRWST flow T Westinghouse u.ssS3 i
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NRC REQUEST FOR ADDITIONAL INFORMATION UNE
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440.583 14 wgp
a NRC RECUEST FOR ADDITIONAL INFORMATiON l
RAl 440.590 l
Page 5-34. Sthparagraph states that the discrepancy shown in the upperplenum calcu 5.2-2) is due to the uncertainty of the measuredpressure values. However, uncertainty cannot a for a one sided difference unless some specialinstruments have been used. Please account f statement and the discrepancy of measured to calculated values.
Response
As discussed in the revised response to RAI 440.563, 'for Test SB10 the pressure measurement transducer was classified as unreliable, so the upper pfenum pressure is based on a differen tranducer than is used for the other tests. For this reason, the WC/T prediction of pressure in relative to the data is not considered to be appropriate in assessing the capability of WC/T to OSU tests.' As shown in the attached Figure 440.5901 from the ACRS meeting of Marc head (and upper plenum) pressures during the period of transition to sump injection and beyo range of 15.6 to 16.0 psia independent of break size and location. Thus, the OSU data value reported for SB10 is considered to be unreliable and inappropriate for assessment of the WC prediction capability.
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Report Revision:
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T Westiflgh0058 440.590-1
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NRC REQUEST FOR ADDITIONAL INFORMATION IB RAI 440.591 The calculational window for SB10 sump injection flow (Figures 5.2-5 and 5.2-6) stops at 14,500 seconds.
This window does not envelop a significant change in the sump injection flow shown in the OSU test data which occurs when the sump injection vakes open. Since the sump isolation vakes opened at 14,600 seconds, the staff believes the window should continued to at least 16,000 seconds to give WCOBRA/TPAC the opportunity to calculate fullsump injection flow.
Re.sponse:
Westinghouse has performed the suggested calculation and provided the results in Reference 440.591 1.
The results can be found in Figures 2.51 through 2.5-28 of that report together with the following paragraph from that report.
The window selected was from test SB10 was initiated at 13,500 seconds, near the end of IRWST injectio and extending to a time of 16,500 seconds at which time both sump check valves and sump isolation valves were fully open. This calculation is an extension of calculation 5.2 in Reference 440.5912. The window included a period of upper plenum liquid level decrease fo!!owing the switchover to sump flow and a subsequent period of increased core steaming rates due to lower DVIline flow rates and higher DVI line liquid temperatures. These conditions were calculated with reasonable accuracy as demonstrated in Figures 2.5 23 and Figure 2.3 21. The total DVI line flow rates into the vessel compared well with the test data during this extended time period as indicated in Figures 2.3 7 through 2.310. It is noted that the suinp and IRWST flow rates and directions are also reasonable well predicted during this period except in portions of line 1 in the period following opening of the sump isolation valve, Figures 2.5-3 and 2.5 5.
In this period, the calculated flow from the sump to the IRWST is higher than measured flow. Of particular significance, however, is the fact that the correct quasi-equilibrium solution is obtained near the end of the transient. This demonstrates, that after a significant perturbation to the boundary conditions (opening of the sump isolation valves), the solution will adiust the flow conditions and retum to the correct values. It is further noted that, during this period, the reactor vessel levels were not significantly influenced.
References 440.591 1. NSD/NRC 97-5014, 'WCOBRA/ TRAC t.ong Term Cooling Letter Report', D.C. Gamer, March 10,1997.
440.5912. WCAP 14776, 'WCOBRA/ TRAC OSU Long Term Cooling Final Verification Report', D.C.
Gamer, et. al., November 1996.
Report Revision:
None g
440.591-1
NRC REQUEST FOR ADDITIONAL INFORMATION IlllEMllill i
i RAI 440.592 Westinghouse assessment of the OSU SB 12 test states on page S 66 that ' the sump flow was inhibited in this calculation'. Why was this done? How is the comparison of sump flow rates meaningful with this
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manipulation of t 1e calculation? Could another test be substituted for this test without inhibiting sump flow?
What is unique in this test for the WCOBRA/ TRAC long term cooling validation?
Response
Test SB 12 data records do not contain a significant period of sump injection. As a result, WC/T calculation comparisons in the sump injection period were considered to be for too short a period to be meaningful.
Further, any deviations from the measurements could not be investigated through erension of the window period. Thus, the comparison with SB12 is intended to address only operation with flow from the IRWST and is included to show the LTC performance for a DEG Direct Vessel Injection Line Break.
Subsequently, a calculation co mparison has been done with SB01 from 18,000 to 19,000 seconds when the the sump isolation valves have been opened and the levels in the IRWST and the sump have equilibrated.
At the start of this cornparison, the equlibrium sump /lRWST conditions have been established for over 2000 seconds so that the comparison addresses specifically sump injection. The comparisons provided in Figures 440.5921 through 440.592 28 show good comparison with the OSU data with the following variations noted:
- 1. The reactor vessel level comparisons are low by 6 to 7 inches in the downcomer and 3 to 4 inches in the upper plenum, Figures 440.592-24 and 440.592-23, which is typical of other test comparsions and is in the conservative direction.
- 2. The core collapsed liquid level is low by about 2 inches, again a deviation in the conservative direction.
- 3. The Total DVI Flows, Figures 440.592-8 and 440.59210 show deviation of +0.040 and +0.065 lb/sec which is within the 2 sigma uncertainity of the flow measurements of + 0.077 lb/sec.
4.
The break flow measurements, Figure 440.592 14, show the same negative trend as the data, however since the magnetic flow meters were not calibrated for negative flows this comparison is not significant.
- 5. As has been indicated in a subsequent RAI, the low flow rates of the ADS 13 which are less than the measurement uncertainity render this comparison insignificant.
Based on the results of this comparison, it appears that WC/T provides a satisfactory quasi-equlibrium solution for LTC during sump operation well after the end of IRWST injection.
Report Revision: None s
[ Westiflgtt0USS 440.592 1 i
FIGURES 440.592-1 THROUGH 440.592 PROVIDED UNDER SEPARATE COVER i
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b O 48 FIGURE 440.593-1 PROVIDED UNDER SEPARATE COVER
NRC REQUEST FOR ADDITIONAL INFORMATION RAI 440.593 In Figure 6-8, the measured and calculated ratios of the inflow and outflow are a function of time. Now would these ratios change if the calculations were performed for longer time intervals.
Response
As indicated in the report, the values presented are the quasi equilibrium values for the four WC/T vs. OSU comparisons. As such, they are average values over periods of 600 to 700 seconds. While all of these cases have not been extended to 3000 seconds, Test SB10 has been. The time wise variations are contained in Table 440.593-1. For the WC/T results, the maximum variation between total flow in and total flow out occurs between 15,000 and 15,500 seconds. This coincides with a slight reduction in vessel liquid inventory in the upper plenum during this period as indicated by Figure 440.593 1. Similiarty, the OSU test data indicates a period of time from 14,000 seconds to 15,000 seconds during which the outflow exceeds the inflow by approximately 6%. This also corresponds to a reduction in upper plenum inventory, Figure 440.593-1, although there appears to be a time shift of approximately 500 seconds. Considering the uncertainity in the flow rate measurements, this agreement is considered good. In any case, the variation in the outflow to inflow parameters with time is small considering variations in DVI line flows in this period of transition from IRWST injection to sump injection.
Table 440.593-1 Total Vessel Outflow / Total Vessel Inflow for SB10 Time Period WC/T Total Outflow /
OSU Total Outflow /
(seconds)
Total inflow Total inflow f
14,000 to 14,500 0.994 14,500 to 15,000 1.005 15,000 to 15,500 1.063 15,500 to 16,000 1.026 16,000 to 16,500 1.044 Report Revision:
None T westinghouse
NRC REQUEST FOR ADDITIONAL INFORMATION RAI 440.594 How were the boundary conditions of pressure, temperature, and void fraction at the break applied? Page 51 WCAP 14776 states that the break separatorlevel, temperature, andpressure were used to determine the boundary conditions. However, page 5-4 states that reverse flow from the break separatorinto the cold leg could not be predicted while page 5 5 states that reverse flow was predictM Simliar statements appear on page 5-93. When reverse flow Is predicted, is the inflow into the reactor coolant system at the appropriate conditions based on the measurements In the break separator? If so, isn't the separator implicitly modeled through the applied boundary conditions?
Response
The statement 'The simulation did not model that break separator, so reverse flow into the cold leg because of the break seperator filling cannot be predicted
- which appears on page 5 4 and also on page l
5-93 is an editorial error. The draft for the report was based on the Preliminary Validation Report, LTCT-GSR-003, which contains this statement. In Reference 440.5941, the break seperator was modeled as a sink / source component with the appropriate pressure, temperature and liquid level. This sentence will be removed in the Revision 1 to Reference 440.591-1.
References:
440.5941. WCAP 14776, "WCOBRA/ TRAC OSU Long Term Cooling Final Verification Report', D.C.
Gamer, et. al., November 1996.
Report Revision:
None T wesunghouse
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NRC REQUEST FOR ADDITIONAL INFORMATION N
RAI 440.595 In WCAP 14776, the predicted downcomerlevel was 15 In. below the measured value for Test SB23. The predicted level was below the elevation of the DVIline while the measured level was at the bottom of the cold leg. The discrepancy is much larger than the error for the other tests (about S in.). Is this discrepancy
?
for Test SB23 significant? Why was predicted downcomer level worse for this test?
Response
The predicted vessel levels in Test SB23 can be understood most clearty when compared to SB01 since the primary difference is the cold leg break flow area. Test SB23 approximates a no break calculation since the hydraulic resistance of a 1/2 inch break flow path is large with respect to the hydraulic resistance of the DVI lines, a factor of approximately 40 greater than the IRWST to vesselline and a factor of 6 to 8 greater than the sump to vessel line Conversely, for the 2 inch break SB01 test, the hydrauhc resistance I
of the break is 161:mes larger and the break is the roughly equivalent of having a third DVI line; assuming that the break separator liquid level is equal to the IRWST level. The separator level is lower but only slightly so during the periods of the window mode calculations. While the reverse break flow magnitudes are suspect due to lack of calibration, it is noted that the indicated break flow rate for the SB01 test is -
i 0.260 lb/sec versus -0.022 lb/sec for the SB23 test. Thus, test SB01 has a significantly different balance of the inlet to outlet hydraulic resistances than SB23 and an increase in the calculated liquid levels of about 4.5 inches in the downcomer and correspondingly in the core plus the upper plenum. With a significantly reduced inlet flow resistance and an increased vessel through flow of only 5% to 10%, it is reasonable to expect the vessel liquid levels to be greater for the SB01 test. Thus, it is concluded that the calculated lower level for SB23 should be expected and does not represent an anomaly in the data comparisons.
Report Revision:
None i
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NRC REQUEST FOR ADDITIONAL INFORMATION R.Al 440.596 WCAP 14776 states (page 6-2) that the pressure drop across the ADS 4 lines is relatively small compared to the resistance of the DVIlines. What are the calculated frictionalpressure drops across the ADS 4 lines and DVIlines during sump Injection for ore of the tests? What is the predicted void traction at the ADS 4 flow nozzles for the corresponding period?
Response
During the early period of IRWST injection when steam formation in the core is minimal, the pressure losses across the ADS 4 valves are small with respect to the DVI line losses. Wrth the initiation of 4
significant boiling in the core, the two phase pressure losses in the ADS 4 valves shift the balance of pressure losses. The calculated frictional pressure drops across the ADS 4 lines and DVI lines during 4
sump injection for a 50 second period of SB 01 sump injection are provided in Figures 440.596-1 and i
440.596 2. These results are taken from the 1000 second window calculation provided in response to RAI 440.592 The short window is being provided with a print frequency of 0.1 seconds to accurately show the pressure drop and void fraction fluctuations. This window is considered to be representative of the larger window and to the general condition of sump injection. The void fractions in the ADS 4-1 and ADS 4-2 valves are provided in Figure 440.596-3
)
Based on the results shown for the sump injection phase, it is concluded that the DVI line pressure drop and and ADS 4 pressure drop are of similiar magnitude during this period. The statement on page (6-2) will be revised as follows:
"The ranking of this parameter has been reduced from high to medium. The basis for the reduction is sensitivity studies, varying the ADS Stage 4 valve losses, which indicated no significant effects on the levels in the core and core coolability during LTC. Therefore, the uncertainity in parameters such as the flow regime and separation at the ADS tee are of reduced importance, and comparisons of the ADS Stage 4 flow rates with WCOBRA/ TRAC are sufficient for the validation of the code pressure drop calculation."
The sensitivity studies which support this conclusion are discussed in the response to RAI 440.597.
Report Revision:
WCAP 14776, Page 6-2, paragraph 2.
W8Stiflgh0058
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O FIGURES 440.596-1 THROUGH 440.596-3 PROVIDED UNDER SEPARATE COVER 1
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NRC REQUEST FOR ADDITIONAL INFORMATION RAl 440.597 WCAP 14776 states on page 6 2 that sensitivity calculations showed that the calculated levels were not significantlyaffectedbyADS-4 losses. Whereare these sensitivitycalculations documented? How sensitive was the total flow through the primary system to the ADS-4 losses during sump injection?
Response
The sensitivity to ADS-4 pressure losses has been calculated for the SB-01 window period of 18,000 second to 19,000 second during which the flow to the DVI lines comes entirely from the sump. In this calculation the loss coefficient of the ADS 4 valves was increased by 50% in both loop 1 and loop 2. As shown in Table 440.5971 below, the total flow through the primary system decreased by approximately 19%. Correspondingly, the collapsed liquid level in the vessel decreased by 0.40 inches. The change in vessel levels is shown in the attached Figures 440.5971 through 440.597-4. The rate of steam generation in the core increases from approximately 0.85 lbm/sec. to 0.95 lbm/sec to compensate for the reduced injection flow rate.
Table 440.597-1 Sensitivity of Vessel Conditions to 50% increase in ADS 4 Pressure Loss Coefficient (Test SB-01)
)
Reference
+50% ADS-4 K, Variation 4
Total Vessel inflow Calculation Calculation DVI1 (Ibm /sec) 0.426 0.368 DVl 2 (Ibm /sec) 0.460 0.392 2' Break (Ibm /sec) 0.068 0.016 Totals 0.954 0.776
-19.6%
Total Vessel Outflow ADS 1,2,3 (Ibm /sec) 0.021 0.021 ADS 41 (Ibm /sec) 0.303 0.220 ADS 4-2 (Ibm /sec) 0635 0.531 Totals 0.959 0.772 18.6%
Upper Plenum Level (in) 6.1 5.7
-0.4 in Downcomer Level (in) 57.5 57.1
-0.4 in Steam Generation in Core 0.850 0.950 (Ibm /sec)
Report Revision: None W85tillgh00$8
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FIGURES 440.597-1 THROUGH 440.597-4 PROVIDED UNDER SEPARATE COVER t
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NRC REQUEST FOR ADDITIONAL INFORMATION rat 440.598 The cskulated upper plenum liquid levels shown in WCAP 14776 are not consistent with the presentation Westinghouse made to the staff on March 12,1991. For example, Figure S.123 of the report shows that the calculated levelis about 14 in. for Test SB-01 while page 45 of the presentation materialshows that the calculated levelis about 9 in. Why are the calculated results different between the report and the presentation?
Response
The upper plenum collapsed liquid levels reported in WCAP 14776 were based upon an inappropriate selection of upper plenum channel for calculating the level in the WC/T plotting package. As shown in Figure 2 2 of the WCAP, there two channels in Section 3 of the upper plenum, channel 15 and channel
- 50. Channel 15 is an annular global channel located adjacent to the core barrel and does not see core outlet flow intering at the bottom. Channel 50 is the core outlet channel and all flow from the core enters this channel. Due to the desire to minimize the number of nodes, these channels have only one vertical node for the 11.9 inch height. As a consequence, the global channel tends to have a high liquid fraction over the entire height while the core outlet channel more correctly reflects the core outlet void fraction.
Using the void fraction in the global channel 15 produces an unrealisticly high indication of upper plenum collapsed liquid level which significantly exceeds the collapsed liquid levelin the downcomer. Conversely, use of the channel 50 void fraction in the collapsed liquid level calculation produces level which compares favorably with the downcomer collapsed liquid level and reflects the manometric relationship between the two flow channels. Thus, subsequent to the WCAP, all reported upper plenum collapsed liquid levels reflect the void fraction in channel 50. The WCAP will be updated to also reflect this basis for the upper plenum levels.
Report Revision:
WCAP 14776, Pages 3-6,3 22,3 38,3-54,5-28,5-59,5-66, and 5118.
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l NRC REQUEST FOR ADDITIONAL INFORMATION General Comment 1.
Westinghouse should consider including the measured and calculated loss factors for the ADS 123 and ADS 4 flow paths in Table 3-7.
Response
1 Pressure loss coefficients for the OSU ADS 123 and ADS 4 lines and valves were calculated from single l
phase handbook data and based on the physical dimensions obtained from the piping drawings. These values were input to WC/T which calculated two phase multipliers based upon the local fluid conditions.
Satisfactory pre-operational test data was not available for comparison. As reported in WCAP-14252, the ADS 123 line resistance was measured, however, the orifice plate, designed to simulate the valves, was not installed. No tests were performed in this test series to determine the pressure loss coefficients of the ADS 4 lines and valves.
Report Revision: None i
l General Comment 2.
The report correctly states that the mass flow through the ADS 123 valves was negligible during the long-term phase. The comparisons between the calculated and measured values are then characterized as excellent for Test SB10, fair for Test SB12, a'id good for Test SB23. The variation in characterizations is inappropriate considering the uncertainty in the data. According to Appendix D of WCAP-14252, the uncertainty in the ADS 123 liquid flow measurement (FMM-601) is 1.342 gpm or about 0.18 lbmisec, which is much greater than the measured values. Furthermore, since the level is near the bottom of the pressurizer during the long-term phase, no liquid flow would be expected through ADS 123. Steam flow through ADS 123 would be expected, but no reliable measurements of the steam flow are available because the instruments were not rangedproperly for the long-term phase. In fact, the reported steam now rate (FVM-601) was less than zero, which is clearly impossible, during the window period for three of the four tests. Thus, the staff has conclude that the ADS 123 flow measurements are very uncertain and that the apparent differences in the ' goodness' of the comparisons for the tests are not meaningful.
Response
In retrospect, we agree. The discussion on the ADS 123 flows in WCAP 14778 will be modified to reflect the significance of the uncertainity in the vapor flow measurements.
Report Revision:
WCAP 14776, Page 5-35 para. 4 Page 5 - *sra. 4, and Page 5-93 para. S.
440.GC-1 T Witstiligh0058
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NRC REQUEST FOR ADDITIONAL INFORMATION
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General Comment 3.
The calculated DVI 1 flow rate reported in the text on page S-65 for Test SB12 (0.87 lbmis) is inconsistent with Figures S.5 3, 5.3~4, and 6-1 (about 1.2 lbnVs). Similarly, page S-66 states that the total calculated ADS 4 flow is 1.12 lbtrVs while Figures S.314, S.3-16, and 6 6 indicate that it is about 1.35 lbnVs. These apparent discrepancies between the text and figures affect the global mass balance discussion on page 5 67 as wellas the summary of results presented in Section 6 (including Figure 6-3).
Response
l The calculated DVI 1 flow rate reported in the text on page 5-65 for Test SB12 should have been 1.14 lbm/sec and the total calculated ADS 4 flow on page 5-66 should have been 1.35 lbm/sec. The values on pages 5-65 and 5 66 were taken from a tabulation which included a earlier WCfr calculation for Test SB12 and had not been updated to reflect the plots in the WCAP.
Pages 5-65 and 5-66 will be updated appropriately. Section 6 was developed from an updated table and contains none of the early calculational results.
Report Revision:
i WCAP 14776, Pages 5-65 and 5-66.
1 General Comment 4.
The mass ratio comparisons shown in Figure 6-8 appear to be contradictory. The figure shows that the rata of flow out to flow in is greater than unity for the tests (indicating that vessel levels should be decreasing) and less than unity for the calculations (indicating that vessel levels should be increasing).
Thus, the trends of the calculation appear to be wrong. The text should justify why these results are adequate.
Response
The text will be updated to reflect a re-evaluation of the predicted ratios which were presented at the ACRS meeting and which showed that WC/T inflow and outflow are equal, Figure 440.GC4-1. The deviations in the measured ratios results primarily from the uncertainity in the vessel inflow and outflow test measurements. This is significant when the negative break flow rates become large, such as in Test SB01, since the flow meters were not calibrated for reverse flow at OSU. This effect is discussed in detail in RAI 440.589 Report Revision:
WCAP-14776, Page 6-3 1
440.GC-2 g
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NRC REQUEST FOR ADDITIONAL INFORMATION l
WC/T Total Inflow / Total Outflow Comparison 2
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2
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=
u 5
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1 15 2
WC/T fotal Calculated Vessel inflow (Ib/sec)
Figure 440.GC41 l
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