ML20133B373

Rev 0 to Evaluation to Increase Normal Drywell Temp Operating Limit

ML20133B373
Person / Time
Site:	Oyster Creek
Issue date:	07/18/1985
From:	Braughton F, Smith P GENERAL PUBLIC UTILITIES CORP.
To:
Shared Package
ML20133B367	List: ML20133B363 ML20133B373
References
TR-024, TR-024-R00, TR-24, TR-24-R, NUDOCS 8508060151
Download: ML20133B373 (17)

Text

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EVALUATION TO INCREASE NORMAL DRYWELL TEMPERATURE OPERATING LIMIT TOPICAL REPORT # 024 i

PROJECT NUMBER: 5400-40715 1 ,

P. S. SMITH July 18, 1985 APPROVALS:

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@ TR 024 Rev. O Page i TABLE OF CONTENTS PAGE 1.0 ABSTRACT 3 2.0' INTRODUCTION 4 3.0 METH000 LOGY 5 4.0 RESULTS 7

5.0 CONCLUSION

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6.0 REFERENCES

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Id TR 024 Rev. O Page 2 LIST OF TABLES AND FIGURES PAGE TABLE 1 ANALYSIS ASSUMPTIONS 6 TABLE 2 PEAK VALUE

SUMMARY

14 FIGURE 1 DRYWELL TEMPERATURE PROFILE FOR DBA LOCA (0-1600 SEC) 9 FIGURE 2 DRYHELL TEMPERATURE PROFILE FOR DBA LOCA (0-160 SEC) 10 FIGURE 3 DRYWELL TEMPERATURE PROFILE FOR EEQ MSLB (0-80 SEC) 11 FIGURE 4 DRYHELL TEMPERATURE PROFILE FOR EEQ MSLB (0-1600 SEC) 12 FIGURE 5 DRYWELL TEMPERATURE PROFILE FOR REMOTE SHUTDOWN 13 PANEL ANALYSIS f

42 TR 024 Rev. O Page 3 1.0 ABSTRACT This report provides a technical basis for increasing the Emergency Operating Procedures entry condition based on bulk drywell temperature from 135'F to 150*F. The normal limit for power operation can be raised to 150*F.

A series of CONTEMPT analyses were performed to determine the sensitivity of containment response for three events starting from different initial drywell temperatures. The analyses covered the containment resprase to the design basis LOCA; MSLB for defining the EQ temperature profile inside the drywell, and the loss of drywell cooling case which defines the limiting drywell temperature condition for the Renote Shutdown Panel study. The temperature profiles for each of these cases do not change significantly when the initial drywell temperature is raised to 150*F.

In all cases, the peak temperatures and pressure are either unchanged or still within the acceptable ranges. Thus, it is concluded that it is acceptable to raise the E0P entry condition on bulk drywell temperature to 150*F and to permit normal plant operations up to this value of bulk drywell temperature.

p N TR 024 Rev. O Page 4

2.0 INTRODUCTION

This report is being prepared to provide technical justification for increasing the entry condition to the Containment Control section of the Emergency Operating Procedures (EOPs) based on drywell bulk temperature.

The intent of this report is to justify raising the entry condition from 135'F to 150*F.

Recently, the operator has begun computing drywell bulk temperature using the algorithm contained in Plant Administration Procedure 106 (Reference 1). The calculated bulk drywell temperature was usually near or a few degrees above the E0P entry condition value of 135'F. In order to prevent the operator from continuously being in the E0Ps, it was proposed to raise the E0P entry condition to 150*F.

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Q 7 TR 024 Rev. O Page 5 3.0 METHODOLOGY The justification to raise the drywell temperature E0P entry condition to 150*F was based on the results from a series of analyses using the CONTEMPT code (Reference 2). The three cases that were analyzed are the

'following:

Design basis LOCA 0.75 ft* MSLB, containment spray initiated at 10 minutes (EEQ Inside Containment Temperature Profile Analysis)

Loss of drywell cooling, 50*F/hr cooldown begun at 10 minutes (Remote Shutdown Panel Performance Analysis) ,

The design basis LOCA was chosen since this break maximizes the energy input into the containment. The steam line break case defines the temperature profile for the environmental qualification of electrical equipment laside the drywell (Reference 3). The last case was used as the limiting case for drywell temperature as part of the remote shutdown panel study (Reference 4). The assumptions used for these cases are listed in Table 1.

47 h TR 024 Rev. O Page 6 TABLE 1 ANALYSIS ASSUMPTIONS DBA LOCA EE0 MSLB RSD PANEL CALC CASE 1A CASE IB CASE 2A CASE 2B CASE 3A CASE 3B Initial drywell pressure, psig 1.2 1.2 1.2 1.2 0.5 0.5 Initial torus pressure, psig 0.0 0.0 0.0 0.0 0.0 0.0 Initial drywell & torus humidity 0.01 0.01 0.01 0.01 0.01 0.01 Initial drywell temperature, F 135 150 135 150 135 150 Initial torus temperature, F 120 120 120 120 85 85

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-Y TR 024 Rev. O Page 7 4.0 RESULTS The results from the six CONTEMPT analyses are summarized in Figures 1 through 5 and the peak values for drywell pressure and temperature are given in Table 2. Floure i shows the drywell atmosphere response for the DBA LOCA over 1600 second period. The long term temperature profile is identical irrespective of the initial drywell temperature. The early portion of the transient shows a slight deviation between the two cases.

This difference is shown in more detail on Figure 2. This figure shows that the post-peak atmospheric temperature profile for Case 1A (initial temperature - 135*F) is greater than that for Case 18. This is caused by condensation in the drywell atmosphere so that energy is transferred to the drywell liquid region, resulting in a slightly higher 11guld temperature profile for Case IB for the first 10 minutes of the transient. It can be seen from Figure 2 that the peak drywell temperature for the DBA LOCA is not dependent upon the initial drywell temperature. This behavior is expected since the difference in drywell atmosphere energy between initial temperatures of 135'F and 150*F is small relative to the amount of energy deposited into the drywell by the blowdown.

The profile of drywell atmosphere temperature for the steam line break case is shown in Figures 3 and 4. Figure 4 shows that the long term temperature profile does not depend on the initial drywell temperature.

Figure 3 depicts the short term temperature increase. The peak b

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I/ TR 024 Rev. O Page 8 temperature is roughly 5*F higher for the case starting from an initial temperature of 150*F when compared to the case starting from 135'F. This difference becomes smaller so that by the end of the first minute of the event, the temperature profiles are the same.

Figure 5 illustrates th'e temperature profiles for the loss of drywell coolers cases. Once the RPV cooldown has begun, the difference in the two profiles is nearly constant and its magnitude is the difference in the initial drywell temperatures for the two cases. The peak drywell temperature of 226*F is reached at roughly 6.3 hours3.472222e-5 days <br />8.333333e-4 hours <br />4.960317e-6 weeks <br />1.1415e-6 months <br />. This value is acceptable since it is well below the design temperature for the drywell liner of 281*F. The increased temperature profile does not cause any detectable total drywell pressure difference because of the reduced initial mass of non-condensibles for the 150*F case. Thus, there is no increased chance of isolating the containment or initiating ADS based on a high drywell pressure signal.

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TR 024 Rev. O Page 14 TABLE 2 PEAK VALUE

SUMMARY

CASE DRYWELL PRESSURE. PSIA DRYWELL ATMOSPHERE TEMPERATURE. 'F IA 55.4 9 6.6 seconds 287.6 9 6.6 seconds 1B 55.2 9 6.7 seconds 287.3 9 6.7 seconds 2A 39.9 9 18.5 seconds 345.4 9 18.5 seconds 2B 39.1 9 21 seconds 347.9 9 18 seconds 3A 16.6 9 22370 seconds 211.1 9 22040 seconds 38 16.5 9 19370 seconds 226.2 9 22620 seconds I

h TR 024 Rev. O Page 15

5.0 CONCLUSION

The results for the LOCA and MSLB cases do not show a noticeable increase in the drywell atmospheric temperature profile when the initial drywell temperature is raised from 135*F to 150*F. In addition, the response of the other containment parameters are not dependent upon which of the two initial drywell temperatures are used.

The loss of coolers case indicates a temperature profile which is higher by roughly the difference in the initial drywell temperatures. However, this profile is acceptable with respect to remaining below the design .

temperature for the drywell line- and remaining below the containment isolation setpoint on high drywell pressure.

Also, since the temperature profiles do not change significantly, the findings of TDR 564 (Reference 5) on the YARNAY level instrument response will still be valid.

Thus, it is concluded that the upper limit for drywell temperature for normal operations may be raised to 150*F. Similarly, the entry condition into the Containment Control section of the E0Ps may be raised to the same value.

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.h TR 024 Rev. O Page 16

6.0 REFERENCES

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1. " Conduct of Operations", Oyster Creek Nuclear Generating Station f Procedure 106, Rev. 32.

2. G. F. Niederauer et. al., " CONTEMPT-EI/28C - A Computer Program for Predicting Containment Pressure - Temperature Transients", Energy Incorporated, EI-81-03, February 1981.

3. N. G. Trikouros, P. S. Smith, "0yster Creek Containment Temperature e for Environmental Qualification of Equipment", GPUN TDh #180, October 1980.

4. A. A. Irant, P. W. Lynches, "0yster Creek Appendix R Drywell Temperature Analysts for Remote Shutdown System", GPUN TDR #660, February 1905.

5. P. W. Lynches, " Preliminary Transient Response Analysis for YARWAY RPV Level Measurement Instrumentation at Oyster Creek", GPUN TDR #564, July 1984.

4 - 6. P. S. Smith, " Increase of E0P Entry Condition on Bulk Drywell Temperature". GPUN TDR 670, March 1985.

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