NRC-92-0095, Responds to NRC 920730 Meeting Request for Addl Info Re 910924 Application for Amend to License NPF-43 Covering Use of Shex Computer Code in Power Uprate Safety Analysis

Responds to NRC 920730 Meeting Request for Addl Info Re 910924 Application for Amend to License NPF-43 Covering Use of Shex Computer Code in Power Uprate Safety Analysis

ML20099H100
Person / Time
Site:	Fermi
Issue date:	08/13/1992
From:	Orser W DETROIT EDISON CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
CON-NRC-92-0095, CON-NRC-92-95 TAC-M82102, NUDOCS 9208180127
Download: ML20099H100 (21)

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August 13, 1992 NP4-92-0095 U. S. Nuclear Regulatory Commission

- Attn t ' Document Control Desk Washington, D. . c : 20555 deferences: 1) - Fermi 2 NRC Docket No. 50-341 NRC License No. NPF-43

2) Detroit Edison Letter, NRC-91-0102 " Proposed License Amendment - Jproted Power Operation", dated September 24, 1991.

Subject:

Detroit Edison Response to NRC Plant System Branch (SPLB)

Verbal Request for Additional Information on Fermi 2 Power Uprate Submittal (TAC No. 8.2102)

Thie . letter formally; provides the additional information requested by the NRC Plant- Systems Branch at the July 30, 1992 meeting held at NRC Headquarters to ' discuss the use of tb- SHEX computer code in the Fermi 2 Power Uprate Safety Analysis.

' Enclosure 1 to this letter provides a request and response format to the

~

.issuco discussed at thar-meeting which were also reviewed in a

-teleconference between Meusrs. T.-Colburn=and J. Kudrick of the NRC and (members of the Fermi 2 licensing staff on~ August 4,-1992.

Please contact Mr. Terry L. Riley, Supervisor, Nuclear Licensing at (313) 586-1684, to coordinate any further actions on this matter, as needed.

Sincerely, i

. Enclosure cc:. T.'G. Colburn A. B. Davis

.Ms P. Phillips S.:Stasek l V

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.DSNRC Aug st 13, 1992

-NRO 92-0095 Paga 2 I WILLIAM S. ORSER, do hereby af firm that the foregoing statements are based on f acts and circumstances which are true and accurate to the best of my-knowledge and belfef.

[ .' Y WILLIAM S. ORSER Senior Vice President On this /d day of !d'Lfi /G' , 1992, before me personally appeared William S. Orserl being first duly sworn and says that he executed the foregoing as his f ree act and deed.

A bysbo 0- [ld Notary Public husAuE A AnaCUA NOTARYItTuc cTri2 cr N'.O UCAN 1dCN"C5 COUN1Y w/ cov.gsf'M EyP, NOV_20.1993 L

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PLANT ANALYSIS SERVICES cc: E. C. Eckert San Jose, California K. M. Fruth F. K. Rhow D. J. Robare C. T. Young DRF-T23-672 August 6, 1992 To: C. H. Stoll From: J. E. Torbeck

Subject:

Responses to NRC Plant System Branch (SPLB) ,equest for Additional Information on Fermi-2 Power Uprate The attached provides the additional information requested by the NRC Plant Systems Branch at the July 30, 1992 meeting held at NRC Headquarters to discuss the use of the SHEX computer code in the Fcrmi-2 Power Uprate Safety Analysis.

Evidence of verification for the attached is contained in DRF-T23-672.

Note that the discussion on " Service Water Temperature" in Response 3 was provided by Detroit Edison, Please forward the attached to Detroit Edison.

t d' J. E. Torbeck Plant Analysis Services Attachment 1

0 .

j 1

-Request 1.

Provide a description of the short term analysis which was performed for power uprate and clarify the application of the "short term" (M3f PT) calculation for containment pressure and the "long term" (SHEX) calculation for suppression pool temperature.

Also provide a comparison for the peak pressure numbers using the same (approved) M3CPT code for a direct comparison with those values documented under the LTP. Provide a table of input parameters used for both calculations and justify any differences.

Response 1.

A short-term containment response analysis was performed for the limiting DBA/LOCA which assumes- a double-ended guillotine break of a recirculation suction line to demonstrate that operation with power uprate will not result in exc'edance of containment design pressure limits. The short-term analysis covers the blowdown period during which the maximum drywell pressure and differential pressure between the drywell and wetwell occur. The analysis was performed at 102% of the-uprated power level using the M3CPT computer code

- (References 1 and 2) which was reviewed and accepted by the'NRC (Reference 3) during the Mark I'Long Term Program (LTP) for application :o Mark I plants including Fermi-2.

The inputs to the M3CPT code which were used for Fermi-2 during the Mark I LTF are compared with those used for Power Uprate in Table 1. Examination of this

- table shows that the input values used for Power Uprate are essentially the same as the LTP input values except for the reactor parameters associated with

~ -

- Power Uprate and some-containment parameters which were updated to be consistent with:the Technical Specifications. The differences in the inputs are identified and discussed in Table 2. As shown in th'is table, the input changes on the RPV conditions due to power uprate caused a-l.8 psi increase in the peak drywell pressure. The differences in other parameters had a minimal impact on the peak drywell pressure. Consequently, the peak drywell pressure calculated at 102% of the uprated power conditions is 49.9 psig, as compared with 48.3 psig calculated at 102% of the current. power for the LTP; this is a 1.6 psi increase due to the combined effects.

Response 1 (con'.inued)

The long-term bulk pool temperature response for Fermi-2 with power uprate was also evaluated for the DBA/LOCA. The analysis was performed at 1027. of the uprated power and 102Y. of the current power using the silex computer code as discussed in Responses 2 and 3 which follow.

l

' Request 2.

Document the one to one comparison performed between SHEX and HXSIZ performed for the December 1991 meeting. Also, discuss the bases for concluding that HXSIZ was (probably) the code used during the original licensing of fermi-2.

Response 2.

SHEX Comparison Wijfh_ji3CPT/HXSIZ The following paragraphs describe information presented in the December,1991 meeting with the NRC. The purpose of the meeting was to provide information to the NRC regarding the SHEX code, and the equivalence of SHEX to the previously used M3CPT/HXSIZ codes. The information given in the meeting is summarized below, as well as a one-to one comparison of SHEX and M3CP1/HXSIZ input parameters used for the evaluation.

During the 1970's, the approach used by GE to calculate the long-term containment response consisted of two codes. The M3CPT code was used to calculate the response from the time of LOCA start to the initiation of containment cooling. The HXSIZ code, which has the capability of modeling the heat exchangers used to cool the containment, was used (with M3CPT output values as input) / rom the time of inittation of containment cooling to beyond the tima t'e peak pool temperature was reached. The approach used by GE in more recent ye,trs (1980's and 1990's) has been to use the SHEX code for long term analysis.-Ihe SHEX code is primarily based on M3CPT, but has the capability of modeling many more auxiliary systems and represents substantial isoprovements over HXSIZ.

The M3CPT code is used to model the short-term containment pressure and temperature response. The modeling used is described in References 1 and 2.

The code consists of the following key components: Reactor Pressure Vessel, Drywell, Vent System, Suppression Chamber Airspace, and Suppression Pool. The f

L vent clearing and vent flow modeling is detailed and is capable of modeling

' highly transient phenomena immediately following initiation of LOCA's. The

! H3CPT code has been qualified extensively against test data and reviewed extensively by the NRC.

I

Response 2 (continued)

The HXSIZ code was used from the mid to late 1970's to model the long term containment pressure and temperature response, and is described in Reference S.

This code has been accepted by the f4RC for BWR containment analysis (Reference 20 of NURFG-0978, Section 6.2.1.4 of flVREG 0979 and Section 6.2.1.4 of NUREG 0887). The code consists of the following key components: Reactor Pressure Vessel, Drywell, Suppression Chamber Airspace, and Suppression Pool.

HXSIZ was applied for times following heat exchanger initiation, using inputs derived from the end conditions of the corresponding H3CPT analysis. The following simplifying assumptions are used: the break flow is equal to the ECCS flow into the vessel, resulting in the RPV water level remaining constant; the vent flow is assumed to be equal to the break flow; the drywell temperature is assumed to be equal to the RPV temt ure; the pressure in the suppression chamber airspace is assumed to be e4 to the drywell pressure; the suppression chamber airspace temperature is assumed to Le equal to the suppression pool temperature, that is, theimodynamic equilibrium is assumed to exist between the suppression chamber airspace and the suppression pool. The HXSIZ code was intended for analysis of a large recirculation line break, and thus is good for only limited applications.

The silex code was introduced for several reasons. One reason was to mechanistically model the drywell and suppru sion chamber airspace responses.

Another reason for developing SHEX was to have the capability of analyzing events other than the DBA recirc break LOCA. Some examples of the events that can be modeled with SHL are: LOCA's of different break sizes and types, RPV isolation, alternate shutdown, 50RV transients, RPV controlled depressurization, drywell bypass leakage, and station blackout. The SHEX code also has the ,-bility to incorporate operator actions, such as control of RPV water level and actuation / termination of containment sprays. Thus SHEX can be used to model a wide variety of accidents and transients and is more versatile than HXSIZ.

Response 2 (continued)

The SHEX code consists of mechanistic models simi.ir to those used in M3CPT, which has been reviewed by the NRC. The mechanistic models are used to remove the simplifying assumptions of HXSIZ as described above. Thus, the RPV, break flow, drywell, suppression pool and suppression chamber airspace models used in SHEX are the same or very similar to those used in M3CPT. The vent flow model in SHEX is also similar to that used in M3CPT, except that the vent clearing model is simplified. The SHEX code incorporates a comprehensive modeling of all the auxiliary systems; neither M3CPT nor HX512 has this additional capability.

In summary, the SHEX code is based on approved methods and provides greater capability for performing long-term containment analyses than M3CPT/HXSIZ.

Extensive verification has been performed for SHEX. SHEX has been vt'idated by comparison of results with M3CPT/HXSIZ results, and by other independent evaluetions such as checks on calculations (e.g. mass and energy balance, flow rates, heat transfer rates) and checks on system logic.

A comparison of the M3CPT/HXSIZ method and the SHEX code was performed. The important inputs, as presented in Table 3, are identical. The M3CPT/HXSIl analysis was performed using Power Uprate initial conditions. This was done because the uprated pow - is the condition of most interest for this comparison. The results of the comparison would also be applicable at a lower power level.

The results of the analysis show that SHEX gives a peak suppression pool temperature of 196.5'F. The M3CPT/HXSIZ codes give a peak suppression pool temperature of 196.I'F. These results are shown in the attached figure. The difference is considered negligible, showing that SHEX is an acceptable alternative to M3CPT/HXSIZ for analyzing the long term suppression pool temperature response.

HXSIZ Anolication for fermi-2 FSAB lt could not be established with certainty that the FsAR long-term containment response analysis was performed with HXSIZ. However, Section 6.2.1,3.6 of the Fermi-2 FSAR giv s the following key assumptions used in the post blowdown model:

Response 2 (continued)

a. Drywell and suppression chamber atmosphere are both saturated (100 percent relative humidity).

b. The drywell atmosphere temperature is equal to the temperature of the liquid flowing in from the RPV or to the spray temperature if the  ;

spray is activated,

c. Suppression chamber atmosphere temperature is equal to the suppression pool temperature or to the spray temperature if the spray is activated.

d. No credit is taken for heat losses from the primary containment. J Assumptions a, b, c and d agree with HXSIZ modeling. Also, figure 6.2-12 of i

-the fermi-2 FSAR shows that the long-term containment-analysis was based on the i assumption-that the suppression chamber pressure is equal to the drywell pressure, which is one of thu key. assumptions for HXSIZ. In addition, the ,

fermi-2 FSAR was docketed in April 1975, which is in the time frame when HXSIZ was being used for long-term containment response analyses. Therefore, it is our opinion that HXSIZ was most likely used in generating the long-term containment response of the. Fermi 2 FSAR. .

s I

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1 Request 3.

Formally provide a comparison of input parameters for the Power Uprate case between SHEX and the UFSAR analysis, discussing significant changes (6) in input parameters and justifying that the changes are conservative or reasonable.

Response 3.

The input parameters used for SHEX for the long term containment response analysis for fermi-2 with power uprate are identified in Table 3. These inputs were developed ba<sd on the best information currently available regarding the Fermi-2 plant configuration. It has not been possible to determine all the inputs used for the original FSAR leng term containment analysis. However, Table 4 identifies differences in the inputs for the power uprate analysis and the FSAR analysis based on information regarding the inputs for the long-term containment analysis in the FSAR.

The following provides a discussion of these differences.

Service Water Temperature The original containment analysis used a constant RHR service water (RHRSW) _

temperature of 90*F which is the maximum design cooling tower outlet temperature. The Technical Specifications prohibits operation with the cooling tower reservoir temperature above 80*F. An energy balance calculation was used to determine the post LOCA RHRSW temperature increase as a function of time from the initial condition of 80*F to the cooling tower maximum design temperature of 90*F. The temperature profile, which is non-linear, was conservatively bounded by a linear profile which was used in the power uprate containment analysis (see Table 4). The following at all of the important assumptions used in the energy balance.

1. The maximum Technical Specification reservoir temperature of 80*F was 1

used as an initial condition.

2. The maximum design cooling tower outlet temperature of 90*F was used.

Response 3 (continued)

3. The minimum Technical Specification RilR reservoir water level was used. This is conservative because it minimizen the heat capacity of the reservoir and maximizes the reservoir heatup.

4. Evaporative and drift losses were used to reduce reservoir inventory during the heatup period.

5. Complete mixing is assumed in the reservoir. Tiiis is conservative because hot water is discharged into the cooling towers and is sprayed down to the surface of the reservoir. Cooler water is drawn from the bottom of the reservoir where the pump suctions are located. ,

No credit was taken for temperature stratification which would have lowered the reservoir discharge temperature profile.

This time variant service water temperature will result in a more realistic suppression pool temperature response than the 90*F service water temperature used for the FSAR analysis.

Suppression Pool Volume The initial suppression pool volume used for the power uprate long-term _

containment analysis was set at 117,161 ft3 which is less than the pool volume of 121,080 f t3 used for the FSAR analysis. 121,080 ft3 corresponds to the T/S minimum value. This lower pool volume of 117,161 ft3 used for the Pouer Uprate analysis adds conservatism to the calculated pool temperature, since a lower initial pool volume results in higher calculated valuet for pool temperature.

Initial Pool Temperature The initial pool temperature for the Power Uprate containment analysis was set at 95'F which is the T/S limit for normal operation. This compares to the nominal value of 90*F which was used for the FSAR analysis. This increase in initial pool temperature results in higher calculated pool temperatures.

, _ . _ . _ _ _ _ _ _ _ _ . . _ _ _ _ . ~ . _ _ _ _ _ _ _ _ _ . _ . . _ _ . _ _ _ _ . _ _ _

i Response 3 (continued) j Feedwater Additiga All water in the feedwater system which could contribute to higher calculated pool temperatures was added to the RPV and containment system for-the Power Uprate analysis. This was achieved by adding all feedwater which is in the feedwater system during normal operation which has a temperature greater than the maximum expected pool temperature. This translates to all feedwater through feedwater heaters numbered 6, 5, 4 and 3.

In' addition, a conservative calculation of the energy in the feedwater piping is added to the RPV/ containment system. This water mass and energy addition assures that the pool temperature calculation conservatively reflect the effect of feedwater addition on suppression pool temperature, it is not certain what feedwater addition was considered for the long-term FSAR analysis, but it is most likely that it did not include any feedwater, g The Power Uprate analysis assumption for feedwater addition will result _in a

higher calculated value for pool temperature than the FSAR assumption.

~

. Initiation Time for Containment Coolina-The FSAR analysis assumed pool cooling was initiated at 10 minutes after the-initiation of the DBA. The Power Uprate long-term containment response analysis has assumed more conservatively that the containment cooling is initiated at 20 minutes which will result in a higher-pool temperature than L that-obtained with the FSAR initiation time.

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Response 3 (continued)

Eqcav H33A The FSAR identified decay hec; values used for the long-term containment analysis which correspond to the May-Witt decay heat model values after 60 seconds. For the power uprate analysis a more realistic decay heat has been included. This decay heat which is based on the ANS 5.1 model (Reference 6) is described in Appendix B of Reference 7. This decay heat includes contributions due to fission heat induced by delayed neutrons, decay heat from fission products, decay heat from actinides (heavy elements) and decay heat from irradiated structural materials. For conservatism additional margin which corresponds to two standard deviations (10%) was added on the decay heat as described in Reference 7, Appendix 0, for the Fermi-2 long-term containment power uprate analysis. This decay heat will result in a more realistic pool temperature than that used in the FSAR, but it is still conservative.

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Request 4.

Summarize the reasoning for the conclusion that the use of SHEX and M3CPT for power uprate calculations are conservative and reasonable.

Response 4.

M)CPT Short-Term Analysis The M3CPT computer code was used to calculate the short-term containment responso for-Fermi-2 with power uprate. This analysis was done to determine the impact of power uprate on the peak drywell pressura which occurs during thc RPV blowdown phase of the recirculation suction line break DBA. M3CPT was reviewed and accepted by the NRC for calculation of the containment pressure and temperature response for Mark I plants during the Mark 1 Containment Long Term Program (LTP). As described in Response I the power uprate analysis using H3CPT was performed with-essentially the same inputs for the containment parameters as those used for the LTP analysis. The RPV conditions were changed to reflect the power uprate conditions. As a result of these changes the calculated peak drywell pressure increased by 1.6 psi to 49.9 psig from 48,3 psig calculated for fermi-2 during the LTP.

In summary, the short term analysis using M3CPT, which was reviewed and approved for use in the LTP, was redone with the uprated power. The 49.9 psig l- peak drywell-pressure for power uprate is well below the UFSAR value of 56.6 psig and the' design value of 62 psig.

l-SiiE)( lona-Term Analuig The SHEX code was csed to calculate the_long-term containnent respor.se for Fermi-2 with power uprate. The primary purpose of this analysis-was to

- determine the impact of power uprate on the calculated peak suppression pool temperature following a DBA-LOCA. SiiEX is a computer code which has been used L

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I Response 4 (continued) by GENE for over 10 years to perform containment long-term analyses which have j been submitted and accepted by the NRC. The key models in SHEX are based on

• M3CPT models which have been reviewea t>y the NRC. To establish confidence in the use of SHEX for this analysis a direct comparison of the peak pool l temperature calculated with SHEX and M3CpT/HXS12 was performed using Fermi-2 inputs at the uprated power as described in Response 2. This showed excellent  ;

agreement. SHEX gave 196,5'F and M3CPT/HX51Z gave 196.l'F. This compaiison is ,

useful as noted in Response 2 in that HXSIZ is the method which is believed to have been used for the original Fermi-2 SAR long term analysis and HXSIZ has been reviewed and accepted by the NRC.

The inputs for the long-term containment analysis with SHEX were based on power

-uprate-conditions. The inputs were selected to provide an up to date representation of the Fermi 2 plant with power uprate and to retain conservatism in all key inputs as described in Response 3. Response 3 identified differences in the ' inputs for the power uprate analysis compared to the original' SAR analysis and justifies the differences. The SHEX analysis was also performed at 102% of the current power with all inputs the same as those  ;

for the power uprate case except for those which are sensitive to power. This analysis' gave a peak pool temperature of 193.6'r compared to 196.5'F at 102% of the uprated power. This shows that the effect of the power uprate, alone, is to increase the peak pool temperature by 2.9'F.

In summary, SHEX evolved from two previously approved codes (M3CPT/HXSIZ) and has _been shown- to give equivalent pool temperature response to the predecessor HXSIZ code. -The long-term analysis for Fermi-2 with power uprate was performed L

with the SHEX_ computer code using conservative inputs and yielded a peak post DBA-LOCA pool: temperature of 196.5'F. This temperature shows margin remains to the controlling limit of 198'F which comes from NPSH requirement for pumps taking-suction from the suppression pnol with no credit _for containment pressure per Reg. Guide 1.1.

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5 TABLE 1 M?CPT INPUT VALUES USED IN FERMI-2 LTP AND POWER UPRATE AllALYSIS JUEQI PARAMETER LTP VALV1 EQWER VPitATE VALVE Core Thermal Power (MWt) 3358 3499 RPV Dome-Pressure (psia) 1020 1063 Core Inlet Enthalpy (Blu/lbm) 525.7 531.1 Initial liquid Mass in RPV (1bm) 640500 640500 _

feedwater Addition to RPV 0. O. ,

~

Drywell Volume (ft3 ) 163730 163730 Initial Drywell Pressure (psig) 0.75 0.75 ,

Initial Drywell Rel. Humidity (%) 20 20 Initial Drywell Tempet ature 135 145 2

Vent flow Area (ft ) 240.9 240.9 Vent flow Loss Coefficient 5.51 5.51 Vent Submergence (ft) 3.33 3.33 Suppression Pool Volume (ft3 ) 121080 124220 Wetwell Airspace Volume tft3 )

130900 127760 Suppreseion Pool Temperature (F) 70 95 Wetwell Airspace Pressuro (psig) 0.75 0.75

7 f i TABLE 2.- .

1 LOMPARISON OF M3 CPI INPUT VALUES BETWEEN LTP AND PDWER UPRATE FOR FERMI-2 . ,

(LTP Peak DW Pressure - 48.3 psig; Power Uprate Peak DW Pressure - 49.9 psig) j l

l

~ POWER UP.. PEASON.FOR IMPACT ON PEAK LTP VALUES VALUES- , DIFFERENCE DRYWELL PRESSURE INPUT PARAMETER Core Therral. 3358-(102 % 3499 (102 % Power uprate Power (MWt) Cerrent Rated)' of Uprated)

Increase by 1.8 psi due RPV Dome Pressure 1020 1063 Power Uprate I to these input changes

- (psia)

Core Inlet' 525.7 531.1 Power Uprate j

. Enthalpy (Btu / ibm)

Drywell . Initial 135 145 Tech. Spec limit for DW 0.2 psi lower with 145 F l

, Temperature (*F) temp. was changed to I4$*F Suppression' Pool 70 95- Tech. Spec limit is used. Negligible impact on Initial Temp. (*F) short-term pressure response 121080 124220 Change to upper limit on. Negligible impact because Suppressiog) '

Pool pool volume. submergence is not changed Volume (ft 130900 127760 Tech Spec upper limit Higher drywell press. with Wetwell Aigspace for pool vol. is used. smaller airspace volume, Volume (ft ) but negligible impact (total wetwell vol. with such small diff.

minus sup. pool.vol.)

t l'

• A Tech Spec amendment was approved to increasa the drywell temperature limit to 145*F from l the original value of 135'F. (See Reference 4.)

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0 TABLE 3 COMPARISDN OF SHEX AND M3CPT/HXSIZ INPUT VALUES FOR FEMI 2 POWER UPRATE ANALYSIS M3CPT/

INPUT PARAMETER EHEX VALUE liXSil VALUE Core Thermal 3499(102% 3499(102%

Power (MWt) of Uprated ofUprated)

Vessel Dome Pressure (osla) 1063 1063-feedwater Addition (1bm) 607638 607638 Decay Heat ANS/5.1+2a ANS/5.1+2a Drywell_ free Volume (f t3) 163730 163730 Suppression-3 Pool Volume (ft ) 117161 117161 Initial Supp.

Pool Temp.-_('F) 95 95

- Initial Wetwell AirTemp.(*F) 95 95

- Initial Wetwell Reiative llumidtty (%). 100 100

- Wetwell Airspace 3

• Free Volume (ft) 134819 l'44819 RHR HXR K (Blu/sec *F) 321 321 RHR Service Water  ;

Temperature-(*F) 80-90 80-90

- RHR Pump Heat (Hp) .2100 2100 L LPCS Pu'mp Heat (Hp) 1600' 1600 Time to Turn on RiiR '

(minutes) 20 20 initial . Drywell Relative Humidity (%) 20 20 L Initial Drywell Pressure (psia) 15.45 15.45 Initial Drywell '

Temperature (*F) .145 145 Initial Wetwell Pressure (psia) 15.45 15.45 H

- a_. - . .

TABLE 4.

Differences in Inputs for fermi-2 Containment long-Term Analysis

$!]EX vs USAR silex USAR Analysis Anal ysi s Service Water Temp Ramped iinearly from 90*f 80*F to 90'f over 8 hrs.

(80*f MAX T.S. limit) (Cooling tower design)

Suppression Pool Volume 117161 ft3 121080 ft3

(< T.S. min. limit (T.S. min limit) forconservatism)

Initial Pool Temperature 95'f 90*f (T.S. max limit) (Nominal value) feedwater Addition All feedwater which Hone can contribute to increased max pool temperature -.

11X Initiation Time 20 minutes 10 minutes Decay lleat ANS 5.1 + margin May-Witt l

e

. 1

References:

1

1. General Electric Co., "The GE Pressure Suppression Containment l System Ar,alytical Model", NE00-10320, April 1971; Supplement 1, May 1971; Supplement 2, June 1973.

2. General Electric Co., "The General Electric Mark III Pressure  !

Suppression Containment System Analytical Model", NED0-205.,J, i June 1974.

3. V. S. Nuclear Regulatory Commission, " Mark I containment Long-Term Program Safety Evaluation Report," NUREG-0661 July 1980.

4. T. R. Quay (NRC) to B. R. Sylvia (Deco), " Amendment No. 20 to [

Facility Operating License No. NPF-43: Drywell Air Temperature Limit (TAC No. 65174)," Docket No. 50 341, June 23, 1988.

5. General Electric Co., "The General Electric Mark III Pressure

. Suppression Containment System Analytical Model Supplement 1,"

NED0-20533-1, September 1975.

6. " Decay Heat Power in Light Water Reactors" ANSI /ANS 5.1 - 1979, Approved by American National Standards initiative, August 29, 1979. ,

7. Generat-Electric Co., "The GESTR LOCA and SAFER Models for the Evaluation of the loss-of-Coolant Accident", NED0-23785-1-A '

Volume III,. October 1984.

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