ML17219A449

Pressure/Temp Limits & Low Temp Overpressure Protection for 10 Efpy.

ML17219A449
Person / Time
Site:	Saint Lucie
Issue date:	01/31/1987
From:	ABB COMBUSTION ENGINEERING NUCLEAR FUEL (FORMERLY
To:
Shared Package
ML17219A448	List: ML17219A447 ML17219A449 ML17219A450
References
NUDOCS 8703240069
Download: ML17219A449 (90)

Text

Attachment 3 Florida Power 8 Light Company St. Lucie Unit 1 P RES S URE/TEMPERATURE LIMITS AND LO)U -TEMPERATURE OVERPRESSURE PROTECTION

'FOR 10 EFPY Report January, 1987 Prepared by Combustion Engineering, Inc.

'OIR for Florida Power and Light Company PDR P 'DR 87032aOOb9 87O317 ADOCK 05000335 MI'IlHf!E SI'7

r P

t pepin g~

I\

il(~

'I!

l

ABSTRACT An analysis of pressure/temperature (P/T) limits and low temperature overpressure protection (LTOP) was performed for St. Lucie Unit I to ensure that= Reactor Coolant Pressure Boundary integrity will be maintained in the low temperature modes of operation during the operating period ending at 10 effective full power years (EFPY).

For that purpose, new P/T limits were developed and a number of administrative and hardware modifications to the existing Overpressure Mitigating System (OMS) were identified. In addition to ensuring adequate LTOP, significant consideration was given to optimization of heatup and cooldown rates and lessening impact of these modifications on plant operating flexibility.

The proposed LTOP system is designed in accordance with the requirements set forth in the NRC Branch Technical Position RSB 5-2. The system will prevent violation of the 10 CFR 50 Appendix G P/T limits during the operating period ending at 10 EFPY. Implementation of the proposed LTOP system will not result in a reduction in the margin of safety presently afforded by Technical Specifications.

This report addresses the methodology and analytical models utilized in the analysis, documents analysis results, and presents the modifications that are necessary for the existing OMS to continue providing adequate LTOP with a minimum impact on plant operating flexibility.

The report provided herein is in support of FPL's request to amend Facility Operating License No,. DPR-67 for the St. Lucie plant, Unit No.

TABLE OF CONTENTS Section Title ~Pa e No.

1.0 INTRODUCTION

2.0 LTOP SYSTEM 2-1 2.1 General 2-1 2.2 Design Criteria 2-1

2. 3 Design Basis 2-3.

2. 4 Proposed ModiQcations 2-4 3.0 PRESSURE/TEMPERATURE LIMITS 3-1

3. 1 General 3-1

3. 2 Fast Neutron Fluence Analysis 3-1 3.3 Material Properties and Adjusted RTNDT 3-2 3.4 Pressure/Temperature Limit Analysis 3.5 Pressure and Temperature Correction Factors 3-6 3.6 Note to Analysis 3-7 4.0 PRESSURE TRANSIENT ANALYSES 4-1

4. 1 General'.2 Energy Addition Transients 4-1 4.3 Mass Addition Transients 4.4 PgRV Discharge Model 4.5 Results of Analyses 4-7

TABLE OF CONTENTS (Cont'd)

Section Title ~Pa e No.

I 5.0 LTOP EVALUATION 5-1 5.1 General 5-1 5.2 Maximum Transient Pressures 5-1

5. 3 Controlling Pressures 5-2

5. 4 Limiting Temperatures 5-4

5.5 Results

Limiting Conditions for Operation 5-7 6.0

SUMMARY

OF PROPOSED CHANGES 6-1

7.0 CONCLUSION

7-1

'.0 ,REFERENCES 8-1

LIST OF FIGURES Number Title ~Pa e No.

3-1 St. Lucie Unit 1 P/T Limits, 10 EFPY, Heatup and Core Critical A-2 3-2 St. Lucie Unit 1 P/T Limits, 10 EFPY, Cooldown and Inservice Hydro A-3 4-1 RCP Start Transients, One PORV Mitigating, 300F, T = 140oF s-p c 4-2 RCP Start Transients, One PORV Mitigating, ht s-P = 300F, Tc = 2000F A-5 4-3 Peak Pressures in RCP Start Transients, One PORV Mitigating, ht s = 300F A-6 P

4-4 Deleted A-7 4-5 Mass Inputs Vs. Pressurizer Pressure A-8 Discharge CoefQcient for Dresser PORV Part No. 31533VX-30 A"10 5-1 St. Lucie Unit 1, 10 EFPY, Maximum Allowable Cooldown Rates A-11

LIST OF TABLES Number 'itle ~Pa e No.

4-1 SI Input/PORV Discharge, Equilibrium Pressures 4-8 5-1 Maximum Indicated Pressures in 'Pressure Transients 5-3 5-2 IdentiQcation of Limiting Temperatures 5-5

P

1. 0 INTRODUCTION The removal of the St. Lucie Unit 1 thermal shield resulted in a reduction in the period of applicability of the current Technical Specification RCS pressure/temperature (P/T) limitations (Reference 1, Fig. 3.4-2b) from 10 years of full power operation to 7.4 effective full power years (EFPY). As a result, starting at 7.4 EFPY, the existing St. Lucie Unit 1 Overpressure Mitigating System (OMS), which was designed based on these P/T limitations, will become inadequate for low temperature overpressure protection (LTOP) for the reactor coolant pressure boundary (RCPB).

An analysis of P/T limits and LTOP was performed to ensure that RCPB integrity will be maintained in the low temperature modes of operation during the operating period from 7.4 EFPY to 10 EFPY. For that purpose, new P/T limits were developed and a number of administrative and hardware modifications to the existing OMS were identified. In addition to ensuring adequate LTOP, a signiQcant consideration was given to optimization of.heatup and cooldown rates and lessening the impact of these modiQcations on plant operating flexibility.

The proposed LTOP system (1) provides assurance that the new P/T limits for 10 EFPY will not be violated during both normal operation and potential overpressurization events due to equipment malfunction or operator error.

Implementation of the proposed LTOP system will not involve a reduction in the margin of safety presently afforded by Technical SpeciQcations and will not significantly impair efQcient operation.

The term "LTOP system" identifies the same concept as OMS, i.e., a combination of hardware and administrative and operational controls which are designated the task of providing LTOP. This term is used throughout this report for the purpose of uniformity with industry practice including St. Lucie Unit 2.

1"1

qual gE

The numerical values of the PORV setpoints, alignment temperatures for

=-

these setpoints, allowable heatup and cooldown rates, temperature limits for disabling of non-essential components, etc., which were identified in the subject analysis, are based on the P/T limit curves which are applicable up to 10 EFPY. However, the proposed LTOP system with more than one PORV setpoint and speciQc administrative and operational controls could also be utilized for operation beyond 10 EFPY. In this case, the numerical values could change, based on new P/T limit curves applicable to an operating period beyond 10 EFPY, but the conQguration of the LTOP system may remain unchanged.

This report addresses the methodology and analytical models utilized in the analysis, documents analysis results, and presents the modiQcations that are necessary for the existing OMS to continue providing adequate LTOP with a minimum impact on plant operating flexibility.

The report provided. herein is in support of FPL's request to amend Facility Operating License No. DPR-67 for the St. Lucie Plant, Unit No. 1.

1-2

2.0 LTOP SYSTEM 2.1 GENERAL The St. Lucie Unit 1 LTOP system in its current conQguration is described in Reference 2. The analyses performed indicate that modifications are necessary for the system to continue providing adequate LTOP beyond 7.4 EFPY. These modifications include:

1. Incorporation of an additional low-pressure PORV setpoint for both PORVs

2. Addition of new administrative and operational controls and broadening the range of the existing controls;

3. Broadening the current temperature ranges, at which non-essential components are disabled during the shutdown mode of operation.

These modifications are addressed in the proposed changes to St. Lucie Unit 1 Technical Specifications and in the following sections of this report.

2.2 DESIGN CRITERIA The proposed LTOP system for St. Lucie Unit 1 meets the design criteria set forth. in Branch Technical Position RSB 5-2 (Reference 3) as follows:

1. The system will prevent exceeding the applicable P/T limits during all anticipated overpressurization events. The analyses performed show that by adding a second low-pressure setpoint, implementing a number of administrative and operational controls and disabling non-essential components, peak RCS pressures will not exceed 10 CFR 50 Appendix G pressure limits at the corresponding temperatures, even while the RCS is in a water-solid condition.

2-1

P

'x I

0 Ol w I 4'.

'k

2. The system will be able to perform its function assuming any single active component failure in addition to the failure that initiated the pressure transient. The most limiting single failure assumed in the analyses was a loss of a PORV. Although pressure transient analyses were performed with one and two PORVs mitigating, the LTOP evaluation that resulted in the proposed LTOP system was based on only one PORV available for mitigation.

.The analyses performed also assumed the most limiting allowable operating conditions and systems conQguration at the time of the postulated overpressurization event.

3. The interlocks and instrumentation associated with the PORVs satisfy the appropriate criteria of IEEE-279. A control room operator can enable the LTOP system by switching the PORV mode selector switch to the low pressure setpoint position during cooldown when appropriate pressure and/or temperature conditions occur. An alarm will alert the operator to enable the system. An alarm is also provided to inform the operator if the PORVs have received a signal to open, which happens when the RCS pressure reaches the PORV setpoint.

4. The LTOP system is testable. The testing requirements are included in St. Lucie Unit 1 Technical Specifications.

5. The PORVs were designed and manufactured in accordance with ASME Boiler and Pressure Vessel Code Section III and are Class I valves.

6. Each PORV is powered from a separate DC control bus. The LTOP system, therefore, does not depend on the availability of offsite power to perform its function.

2-2

1 C

II

.fp s.ak,

2.3 DESIGN BASIS.

1, The proposed LTOP system is designed based on new P/T limits which are applicable for 10 EFPY. These P/T limits are addressed in Section 3.0 of this report.

2. In the design of the proposed LTOP system, the following overpressurization events were considered:

I. Mass Addition Events

l. Actuation of two HPSI pumps with all three charging pumps,

2. Actuation of a single HPSI pump with all three charging pumps,

3. Actuation of a single HPSI pump when all charging pumps are disabled, and Actuation of three charging pumps when all HPSI pumps are disabled.

The low pressure safety injection (LPSI) pumps and safety injection (SI) accumulator tanks were not considered as contributing sources since the LPSI pump shut-off head (170 psig at 60~F) and SI tank design pressure (250 psig) are below the applicable P/T. limits. This is consistent with the approach utilized in the design of the existing OMS.

II. Ener Addition Events Reactor coolant pump (RCP) start, with a positive secondary-to-primary temperature differential (ht s-p ),

2. Decay heat addition due to Shutdown Cooling System (SDCS) isolation, and

3. Inadvertent pressurizer heater input.

2-3

These analyzed mass and energy addition events are similar to those considered in the design of the existing OMS as indicated in Reference 4. The analytical models and assumptions used in the analyses are addressed in Section 4.0 of this report.

3. St. Lucie Unit 1 Technical Specifications provided a basis for determining the most limiting (worst-case) overpressurization events and applicable temperature ranges for these events.

4. A comparison between the peak pressures in the most limiting events and the P/T limit curves (see Item 1 above) provided a basis for the modiQcations to the existing OMS so that during no LTOP event will these peak pressures exceed applicable P/T limits.

F

2. 4 PROPOSED MODIFICATIONS 2.4.1 Hardware

1. The existing setpoint of 465'psia is increased to 530 psia for both PORVs.

2. A second low-pressure setpoint of 350 psia is added to both PORVs.

"As a result of this modification, both PORVs V1402 and V1404 will have two setpoints for LTOP.

2.4. 2 Administrative and Operational Controls

1. The maximum LTOP temperature (TLTOP), i.e., the upper temperature limit for the LTOP mode of 'operation, is increased r

from the current 275~F to a new value, equal to T = 334~F.

2-4

2. The new temperature limits for alignment of the PORVs are as follows:

PORV Setpoint Heatup Cooldown 350 psia 80oF <

c-T < 180oF 80oF < T c

< 200oF 530 psia 180F< T c<334F 200 F < T c< 334 F The PORVs are not required for LTOP below 140<'F when the RCS does not have pressure boundary integrity. (This is consistent with the present limitation). At T > 334~F, the PORVs have a "high pressure" setpoint of 2400 psia.

3. The new maximum allowable heatup and cooldown rates (See Section 5.5, Items 2 and 3) are more limiting than those currently in Technical Specifications.

4. The maximum secondary-to-primary temperature differential for RCP,starts (at s-p ) is reduced from the current 45~F to a new value, equal to 30 F.

5. The current pressurizer water volume requirement for RCP starts (less than 40% indicated level) is deleted.

6. The minimum RCS temperature for two HPSI pumps to be operable is increased from the current 215~F to a new value, equal to T c = 253~F.

7. The minimum RCS temperature below which all HPSI pumps must be disabled is increased from the current 165~F to a new value, equal to T c = 220~F.

2-5

'l J

7y tv

The flow path from the RWT to the RCS via a HPSI pump shall only be established if the RCS pressure boundary integrity does not exist, or if no charging pump is operable in which case all charging pumps shall be disabled and heatup and cooldown rates shall be further restricted as compared to these in Item 3 above. The rates associated with this limitation are specified in Subsection 5.5, Item 8.

This limitation is more restrictive than that applicable to the existing OMS.

2.4.3 Technical S ecifications The proposed changes to the existing OMS (Subsections 2.4.1 and 2.4.2) lead to a modification to St. Lucie Unit 1 Technical Specifications. A list of the affected technical specifications is provided below. The changes are indicated on marRed up copies of the affected technical specifications and corresponding bases.

LIST OF AFFECTED TECHNICAL SPECIFICATIONS

1. 16 3.1.2.3 3.4.13 3.1.2.1 3.4.1.4.1 3.4.14

'.1.2.1 3/4.4.9 3.5.3

jl'r J'W 4 5

3. 0 PRESSURE/TEMPERATURE LIMITS 3.1 GENERAI The new P/T limits were calculated in accordance with the requirements of Appendix G, 10 CFR Part 50 (Reference 5). The limits were devel-oped based upon the recommendations of Appendix G of the ASME Boiler and Pressure Vessel Code Section III (Reference 6). These limits are dependent upon the initial reference nil-ductility transition temperature NDT for the limiting materials in the beltline and closure Qange (RTVDT) juncture regions of the reactor vessel and upon the increase in RT NDT resulting from fast neutron'irradiation damage to the beltline materials.

The P/T limits are presented in Figures 3-1 and 3-2.

3.2 FAST NEUTRON FLUEiVCE AiVALYSIS The St. Lucie Unit 1 P/T limits for 10 EFPY have been calculated using a surface fluence of 7.8 x 10 18 n/cm 2 (E > 1 MeV), at the position of the limiting lower shell welds 3-2038 and 3-203C. The fluence was determined using a calculational model as described in report TR-F-MCM-004 (Reference 7). The report contains Combustion Engineering's (C-.E's) analysis of the dosimetry in Surveillance Capsule N-97.

/

The calculated peak neutron Quence for the vessel surface at the end of life (2700 Mwt for 32 EFPY) using the results of the N-97 capsule and a Cycle 6 low leakage core power distribution for extrapolation is 3.5 x 10 19 n/cm 2 (E > 1 MeV). The Cycle 6 power distribution included r

an axial peaking factor of 1.1. Using the same calculational model with.a

.; core power distribution that will bound. all'uture low. leakage fuel ..

management sch,emes, the best estimate peak fluence is 4.5 x 10 19 n/cm 2 (E > 1 iMeV). The peak neutron reactor fluence does not occur at the location of the limiting weld. This bounding distribution used an axial peaking factor of 1.2. The data were calculated based upon a detailed octant symmetric DOT model'f the core to vessel configuration and an 8.625" vessel wall thickness, with 2700 Mwt power operation.

3-1

e 4

0 4

6

As noted in report TR-F-MCM-004, the quoted peak fluence was represented by a model with a uniformly thick core support barrel. As shown in report CEN-272(F)-P (Reference 8), consideration of the non-uniformities in the St. Lucie Unit 1 core support barrel results in a 245 increase in the vessel fluence. However, this increase is localized to positions opposite to the core support barrel plugs. The limiting weld locations on the St. Lucie Unit 1'eactor vessel are in the lower shell and are not affected by the non-uniformities in the core support barrel.

3.3 MATERIAL PROPERTIES AND ADJUSTED RTNDT The St. Lucie Unit 1 reactor vessel was manufactured to ASME Code requirements for initial material properties. The initial RT T of various reactor vessel plates, forgings and welds, along with the initial RTNDT of materials outside of the beltline, provide the basis for the pressure/temperature limits.

The maximum RTVDT NDT associated with the stressed region of the reactor vessel flange during boltup is 30~F and is located at the vessel flange juncture. This maximum RT T establishes the minimum boltup temperature when corrected for the temperature instrument uncertainty of 6~F per ASME Code Section III, Article G-2222 (Reference 9). For conservatism, the minimum boltup temperature is established as 80~F.

The maximum RT for the balance of the Reactor Coolant System components, excluding the reactor vessel, is estimated to be 90 F. This estimate is based upon similar Byron Jackson Pumps used at other nuclear plants which have a maximum RTNDT of 90~F. This maximum RTNDT controls the Lowest Service Temperature. The Lowest Service NDT for the Temperature is defined as equal to the maximum RT<DT balance of RCS components plus 100~F per the ASME Code Section III Article NB

/

2332 (Reference 10). Therefore, the Lowest Service Temperature is 196~F when corrected for the temperature instrument uncertainty of 6~F.

3-2

The limiting materials in the reactor vessel beltline are welds which were fabricated by C-E using the submerged arc weld process. The limiting welds are the lower shell longitudinal welds 3-203A and 3-203C, due to their high copper and nickel content. The material and chemical content for these welds are .30 w/o and .64 w/o for copper and nickel, respectively. These values are based upon chemical analysis of weld deposits using the same weld wire and flux as that used in the vessel construction. The initial RTNDT for these welds is -56 F with a standard deviation of 17OF. These values are based upon generic values for C-E's submerged arc welds as formulated in C-E's Pressurized Thermal Shock evaluation (Reference 11).

The RTNDT of the lower shell longitudinal welds increases over time due to fast neutron irradiation damage. This adjusted RT<DT N is calculated using Regulatory Guide 1.99 Revision 02 shift correlation with thru-wall fast fluence. The adjusted RT T for the 1/4t and 3/4t locations using this method is 161 F and 93~F, respectively. C-E chose this modified Regulatory Guide 1.99 Revision 02 method as opposed to following the suggested guidance of Regulatory Guide 1.99 Revision 02 verbatim, for the following reasons:

1. Calculated fluence values were verified using in-vessel/ex-vessel dosimetry measurements. Flux magnitude and distribution was verified through supplemental neutron dosimetry following thermal shield removal.

2. The use of thru-wall fast fluence is consistent with the basis of the shift rediction correlation of Regulatory Guide 1.99 Revision 02.

The shift prediction correlation of Regulatory Guide 1.99 Revision 02 is not based upon displacement per atom (DPA) considerations.

3. At the 3/4t location, the Regulatory Guide 1.99 Revision 02 attenuation model suggests a 60 to 74% higher effective fast fluence based upon neutron spectrum differences with a resultant 16-21%

3-3

ih' "$

1 P'

\'4 wl C

~1 1r I

higher RTN T shift. Yet,. there is very limited and rather inconclusive evidence to justify imposing an additional margin to the adjusted RTNDT value. The existing applied margin of 65.5'F adequately accounts for any neutron spectrum uncertainties.

3. 4 PRESSURE/TEMPERATURE LIMIT ANALYSIS The criteria from Section III of the ASME Code Article G-2000 (Reference

6) was used to calculate the P/T limits associated with a postulated flaw in the reactor vessel. Flaws are postulated on the inside surface and on the outside surface of the pressure vessel. The distance is measured from the inner radius of the vessel outward. The flaws on the inside surface and outside surface of the vessel are referred to by location as 1/4 thickness (1/4t) and 3/4 thickness (3/4t), respectively. The postulated flaw is a semi-elliptical surface flaw oriented in the axial direction with a 1:6 aspect ratio. The flaw is assumed to have a depth of 1/4 of the reactor vessel wall thickness or 2.16 inches.

The Reference 6 procedure is based upon the principles of linear elastic fracture mechanics and involves a stress intensity factor prediction which is a lower bound of the static, dynamic and crack arrest critical values. This conservative methodology insures the P/T limits provi'de assurance that the RCPB behaves in a non-brittle manner and the, probability of rapidly propagating fracture is minimized.

Several critical locations of the reactor vessel were considered. At each location being analyzed, a maximum postulated flaw was assumed. At the same location, the Mode I stress intensity factor, KI, was calculated for the specified pressure and thermal loadings. The sum of the KI values was compared to a reference stress intensity value, KIR, which is the highest critical value of ICI based upon static, dynamic, and crack arrest fracture toughness values that can be ensured for the material and 3-4

temperature involved. The reactor vessel beltline, flange juncture, and nozzle regions have been evaluated using the postulated defects permitted by Reference 6.

P/T limits have been established for inservice hydrostatic tests, for various heatup and cooldown rates, and for core critical operation. For inservice hydrostatic tests, the criteria from Reference 6 requires KIR to be at least 1.5 times the KI caused by pressure. Consequently, the inservice hydrostatic test P/T limits are based upon the fracture mechan-ics expression 1.5 KIM < KIR. The flaw on the inside surface of the lower shell longitudinal welds is limiting for the inservice hydrostatic tests.

For non-critical operation with various heatup and cooldown-rates, the criteria from Reference 6 require KIR to be at least the sum of 2.0 times the KI caused by pressure and the KI caused by thermal gradients.

Consequently, the P/T limits for various heatup and cooldown rates are based upon the fracture mechanics expression 2.0 KIN + KIT <

cooldown, the flaw on the inside surface location of the lower KIR'uring shell longitudinal welds is always limiting since the adjusted RTNDT is higher than that at the 3/4t location and both the thermal and pressure stresses are tensile. During heatup, either the flaw in the lower shell longitudinal weld inside surface or outside surface location is limiting.

Therefore the heatup P/T limits are composite curves based upon both the 1/4t and 3/4t flaw locations.

Limits for core critical operation are provided as required by 10 CFR Part 50 Appendix G (Reference 5). These limits are applicable when the core is critical except for when the core is critical for low power physics tests. These core critical P/T limits are strictly based upon fracture mechanics considerations. The core critical P/T limits- are deflned as being at least 40OF above the minimum permissible and'stablished temperature corresponding to the limiting heatup or cooldown P/T limit curve and greater than the minimum possible temperature for the inservice system hydrostatic test pressure.

3-5

I SY Vp

(~(

Although the flange and nozzle regions were evaluated using a detailed fracture mechanics procedure in accordance with ASME Code Section III Appendix G requirements, the P/T limits for these areas were not as limiting as the reactor vessel beltline limits. Consequently, the composite P/T limits do not include nozzle or flange limits based upon Appendix G considerations.

3.5 PRESSURE AND TEMPERATURE CORRECTION FACTORS The P/T limit curves hive also taken into account allowances for instrument, hydrostatic, and hydrodynamic errors in sensing actual pressure and temperature conditions. The pressure correction factors used to develop these curves vary as a- function of flowrate in the RCS..

The pressure correction factors utilized include instrument uncertainties and elevation head differences between the vessel beltline and pressurizer pressure instrument tap. The pressure correction factors used to correct the analysis results to indicated pressurizer pressure are as follows:

Pressure Indicated Cold Leg Temperature Correction Factor (PSIA) (T oF) PSIA c

> 1500 psia 96

< 1500 psia 200oF 66

< 1500 psia 200oF 54 The temperature correction factor utilized is the actual temperature instrument loop uncertainty as obtained through the statistical combination of the individual component errors. The temperature correction factor utilized to correct the analysis results to indicated cold leg temperature is 6.0~F.

3-6

>o

~ q

3. 6 NOTE TO ANALYSIS During a recent conference call between the NRC, FPL and C-E, the NRC has indicated that any newly proposed P/T limits would be reviewed by the NRC staff using the Regulatory Guide 1.99 Revision 02 methodology to verify the predicted RTNDT shifts. The NRC has also indicated that alternative RTNDT shift prediction methods can not be utilized in P/T limit calculations without prior NRC approval.

Before this NRC position became known, C-E had generated new P/T limits for St. Lucie Unit 1 through end of life, i.e., for 10 EFPY, 15 EFPY, 20 EFPY, etc. In the development of these P/T limits, the adjusted RTNDT values were calculated based upon Regulatory Guide 1.99 Revision 02 RTNDT shift correlations without the Revision 02 flux spectrum adjustment factor.

While C-E is confident that the margin of conservatism this method yields is adequate, the adjusted RT T values resulting from application of this method differ from those yielded through strict application of Regulatory Guide 1.99 Revision 02, i.e., including the flux spectrum adjustment factor. The difference is especially noticeable at the 3/4t location which controls P/T limits for heatup at the lower temperatures.

At the 1/4t location which controls P/T limits for cooldown and P/T limits for heatup at the higher temperatures, the difference in the adjusted RTNDT values is marginal.

In light of the above considerations, the following solution was found:

1. New composite P/T limit curves for heatup were generated using the available P/T limits for the 3/4t location, based upon fluences at 20 EFPY, and using the available P/T limits for the 1/4t location, based upon fluences at 10 EFPY.

It is estimated that substitution of the 20 EFPY fluence for the 10 EFPY fluence compensates for the difference in the predicted

.t lg 0

adjusted RT values that results from the two above-mentioned methods. It is, therefore, expected that these composite P/T limit curves for heatup will be acceptable to the NRC for the operating period ending at 10 EFPY.

Since the difference in the predicted adjusted RTNDT values for the 1/4t location, resulting from the two methods, is marginal (see above), the 10 EFPY P/T limits for cooldown based on the 10 EFPY fluence and the C-E's adjusted RTNDT prediction methodology are also expected to be acceptable for 10 EFPY.

2. Pursuant to the NRC position, C-E is planning to prepare a topical report on the C-E's methodology for predicting adjusted RTNDT shifts for NRC review. The previously generated P/T limits for beyond 10 EFPY will be submitted to the NRC at a later date.

3-8

/>

, I. ~ a 'l%

?

++

4.0 PRESSURE TRANSIENT ANALYSES

4. 1 GENERAL The same design basis events as those considered previously (see Reference 4) were re-analyzed using modiQed analytical models and additional assumptions. Some of the previous assumptions were also applied again in each pressure transient analysis. These assumptions are:

Letdown flow paths are isolated, No heat absorption or metal expansion in the RCPB, and Pressure transients are mitigated by one PORV.

Although the mass addition transients were also analyzed using two PORVs for mitigation, the results of these analyses did not provide a basis for the proposed LTOP system because of the single failure criterion.

NodiQcations to analytical models and assumptions were based upon new test data, speciQcally that related to PORVs, and upon a new approach to the LTOP evaluation which was targeted at maximizing heatup and cooldown rates while preserving operating flexibility. This approach required the pressure transient analyses to be performed in a parametric manner, assuming a number of parameters such as PORV setpoints, initial conditions, decay heat rates, etc. Consequently, a sufQcient data base was generated to help identify optimal LTOP characteristics thus avoiding overly conservative operational limitations.

The analytical models and assumptions utilized in the pressure transient analyses are addressed in the following subsections.

r 4.2 ENERGY ADDITION TRANSIENTS Out of the design basis energy addition transients listed-in Subsection 2.3, the pressure transient due to a RCP start when the secondary 4-1

hc

~g~~pq ~ .i C

~ kp e

steam generator inventory is at a higher temperature than the primary (RCS) inventory, is the most severe. Accordingly, only this transient was analyzed. However, similar to the previous analyses, an additional heat input due to decay heat and simultaneous operation of the pressurizer heaters was included for conservatism.

The same computer model as was described in Reference 4 was used to analyze the. water-solid RCS pressure response resulting from a single RCP start with one PORV mitigating. These analyses were performed for four PORV setpoints. (320, 360, 400, and 465 psia) and two RCS temperatures (140 and 200~F). Also, the same analyses were performed assuming that the analyzed transients take place either at the PORV inlet or in the pressurizer. The transients were followed for 20-40 seconds from the initiation to verify that RCS pressures reached a peak.

The following major assumptions were used in these analyses in addition to the assumptions mentioned above.

Water-solid conditions in the pressurizer.

Secondary-to-primary temperature differential (ltsp ) is 30~F

• RCP flow rates are based on hot functional tests~

Only one RCP is started at a time 1% decay heat, full pressurizer heaters input and the heat input from RCP operation Initial saturated conditions in the pressurizer.

An evaluation of the results of the parametric study indicated that the previous analyses (see Reference 4) contained a conservative assumption with respect to,the analyzed pressure transients taking place at the PORV inlet. Based on that assumption, pressure drops in the PORV inlet piping were usually added to the peak transient pressures identified in the computer analyses to arrive at the peak pressurizer pressures.

• These assumptions were modified as compared to the previous analyses.

4-2

~kgb

'i< '

The evaIuation proved that expressing PORV discharge vs. pressurizer pressure rather than vs. PORV inlet pressure and assuming the tran-sient takes place in the pressurizer yields more realistic results. In other words, peak pressurizer pressures based on this new assumption are lower than those based on the old assumption, all other conditions being equal. This positively affects LTOP characteristics, especially heatup and cooldown rates.

The results of the computer analyses are presented in Figures 4-1 and 4-2. Figure 4-3 which is derived from these two figures is further used in the LTOP evaluation. The curves in Figure 4-3 are extrapolated beyond the last analyzed opening pressure of 465 psia since it is appar-ent that starting with this pressure, the peak pressures associated with T = 200 F are approximately equal to the opening pressures, while at c

T c

= 140~F, that starting point is at an even lower opening pressure.

4-3

g a4 \'r

'C

4.3 MASS ADDITION TRANSIENTS A number of mass addition events based on possible combinations of HPSI and charging pumps were analyzed using the same methodology as in Reference 4, i.e., a method of equilibrium pressures. Additionally, a simultaneous operation of one HPSI and two charging pumps was analyzed using a computer simulation to verify the accuracy of the traditional method.

Out of those analyzed, four events (see Subsection 2.3) provided a basis for the proposed LTOP system.

Although the same methodology was used, the assumptions were modiQed, which signiQcantly affected the equilibrium pressures. This affect was mostly due to including decay heat and the pressurizer heater input, the maximum rather than the nominal flow rate resulting from two HPSI pump operation, and a different PORV discharge model.

The major assumption which affected mass inputs are discussed below while the PORV discharge model is addressed in Subsection 4.4.

1. Mass inputs into the RCS resulting from two HPSI pump operations can vary from the minimum to the maximum. The maximum inputs increase equilibrium pressures, all other conditions being equal.

Accordingly, the maximum inputs were assumed in this analysis, which is reflected in Curve 7, Figure 4-5.

2. Full pressurizer heater capacity was assumed to contribute to the total effective mass inputs. Each curve in Figure 4.5 is affected by this assumption.

3. Decay heat input was assumed as another contributor to the severity of the mass addition transients.

4-4

Although mass addition events can occur while the SDCS is aligned and in operation,- due to a relatively small PORV capacity.and the single failure criterion, an anticipated range of equilibrium pressures is above 268 psia at which the SDCS is automatically isolated from the RCS. Thus, the decay heat removal capability.

will be lost, which will result in reactor coolant expansion and, consequently, in increase in the total mass to be relieved by a PORV.

4. Various rates of decay heat were assumed depending on applicable RCS temperatures. A link between decay heat and an RCS temperature is time after shutdown. According to Reference 13, the RCS can reach the SDCS entry temperature of 325~F and the refueling temperature of 140 F in 3.5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br /> and 27.5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br /> after reactor shutdown, respectively. A fission products decay heat curve indicates 1% and 0.6% decay heat rates corresponding to the above time frames, respectively.

Based on the discussion above, a decay heat rate vs. RCS temperature curve, in a form of a straight line, was plotted. This curve was used to determine appropriate decay heat values in the mass addition transient analyses as well as in the RCP start transient analysis.

PORV capacity curves developed based on different assumptions (see Subsection 4.4) were superimposed on the curves in Figure 4.5 to determine the equilibrium pressures which were further used in the LTOP evaluation.

Table 4-1 summarizes the results of the mass addition transient analyses.

4-5

o

-n Cg

4. 4 PORV DISCHARGE MODEL A standard Bernoulli equation for oriQces was used to predict liquid

.PORV discharge in the analyzed transients. The same model was also used in the previous analyses (see Reference 4), with a constant dis-charge coefQcient of 0.6 for any PORV inlet condition.

However, a series of tests performed with a Dresser PORV indicated that PORV capacity was a function of liquid subcooling at the PORV inlet.

Test results (Reference 14) demonstrated that overestimated PORV capacity would result if the existing discharge model or the discharge coefficient of 0.6 are used under low subcooling conditions. This is clearly illustrated in Figure 4-6 which is based on Reference 14.

Out of several PORV discharge models evaluated in the subject analysis, the above-mentioned Bernoulli equation with a variable discharge coeffi-cient provided the best correlation with the test results. Accordingly, PORV capacity curves were calculated using this model.

Several PORV capacity curves were developed to more accurately match anticipated initial and transient conditions. The reason was that dif-ferent PORV discharge flow rates will result at the same PORV inlet pressure at different initial conditions. It is best illustrated by the following example.

Assuming a RCS pressure of 400 psia at the initiation of a mass addition transient when the SDCS is not aligned and the corresponding pressuri-zer saturation temperature of 444.6 F results in liquid subcooling (AT) of 22.4 F at the PORV inlet pressure of 500 psia. The corresponding discharge coefQcient is 0.407, per Figure 4-6, and the resulting PORV flow rate is 488 gpm.

If a pressure of 260 psia and a temperature of 404.4~F (the saturation temperature at 260 psia) are assumed, aT at P = 500 psia is equal to 62.6~F, the discharge coefQcient is 0.531 and the PORV flow rate is 626 gpm.

'l

'ly "I

I graf,

$~P Ja

I Analysis indicates that reducing the initial pressure and the corresponding saturation temperature results in greater PORV flow rates, lower equilibrium pressures and, finally, better LTOP characteristics.

The following PORV capacity curves were developed. Refer to Figure 4-5 for application.

a. For use with Curves 6 and 7. Assumptions: Variable discharge coefQcient; P 0 = 400 psia and T 0 = 444. 6'F.

b. For use with curves 2, 4, and 5. Assumptions: Variable discharge coefQcient; P = 260 psia and T = 404.4~F.

c. For use with curves 1 and 3. Assumptions: A constant discharge coefQcient of 0.61 based on highly subcooled conditions in the pressurizer at low RCS temperatures.

d. For use in the RCP start transient analysis. Assumptions:

Variable discharge coefficient; P 0 = 300 psia and T 0 = 417.3~F.

4.5 RESULTS OF ANALYSES The final results of the pressure transient analyses are presented in Figure 4-3 and Table 4-1.

4-7

Table 4-1 SI INPUT/PORV DISCHARGE EQUILIBRIUM PRESSURES INPUT EQUILIBRIUM PRESSURE REFERENCE ONE PORV TWO PORVs Two HPSI and Three 1040 psia (2) 650 psia Curve 7 in Fig. 4-5 Charging Pumps and PORV Case a, per Subsection 4.4.

One HPSI and Three 740 psia 475 psia 6 and a 660 psia

~ (3) 365 psia

~ (3) andb Charging Pumps 5 psia (3) psia (3) andb

~

Three Charging Pumps 260 ~

<100 2

<100 psia (4)

<100 psia

~ (4) 1 and c psia (3) psia (3) and b

~

Single HPSI Pump 545 330 4 460 psia (4) <250 psia (4) and c

~ ~

3 NOTE: (1) These equilibrium pressures were determined using PORV capacities two times greater than those for one PORV.

(2) Applicable at all temperatures within the LTOP mode.

(3) Applicable at T < 220<'F.

(4) Applicable at T < 140~F.

4-8

4 pQ'~g,: l),

y~g4 sQg 3 tw

.C "IhVI p'<1

'I gk AS

5. 0 LTOP EVALUATION 5.1 GENERAL New PORV setpoints were selected for the proposed LTOP system, as follows:

P = 350 psia, for the lower temperature region set1 P = 530 psia, for the remaining part of the LTOP mode.

set2 An evaluation of the pressure transient results with these PORV setpoints yielded the maximum RCS pressures for each transient. A comparison of these maximum pressures determined the most limiting transients and the controlling pressures . Application of these controlling pressures to the P/T limit curves, Figures 3-1 and 3-2, resulted in the limiting temperatures for PORV alignment, heatup and cooldown rates, and o p eration of HPSI and charging pumps.

5.2 MAXIMUM TRANSIENT PRESSURES The maximum RCS pressures resulting from the design basis mass and energy addition transients were determined based on the results of the transient analyses (Subsection 4.5), assuming the PORV setpoints of 350 psia and 530 psia and correcting for instrument inaccuracies.

For St. Lucie Unit 1, and instrument error in pressure indication is 1

+10.3. psi, which is mostly attributed to a pressure transmitter. This error is applicable to the 0 to 1600 psia pressure range. Similarly, an instrument error associated with PORV actuation is +21.1 psi, which implies that a PORV can open at as high as 21.1r above a setpoint, or as low as 21.1 psi below a setpoint. Thus, the PORV opening pressures were assumed as:

(1) The controlling pressures concept is discussed in Subsection 5.3.

5-1

i4~

I (4;

P

P = 350 psia + 21.1 psi, and open>

P = 530 psia + 21.1 psi open>

Assuming that the pressure instruments could read either "high" or "low", the most conservative indicated pressures were determined in each transient. (Refer to Table 5-1.) In some transients, such as mass addition due to three charging pumps, in which the equilibrium press'ures were below the PORV setpoints, the maximum indicated pressures were based on the PORV opening pressures. The maximum pressures in Table 5-1 are based on single PORV mitigation.

5. 3 CONTROLLING PRESSURES Based on Table 5-1 and the P/T limit curves, Figures 3-1 and 3-2, the most limiting pressure transients along with the applicable temperatures were determined and the corresponding maximum indicated (i.e.,

controlling) pressures were identiQed.

A controlling pressure generally identifies an RCS pressure limit which will not be exceeded'during any overpressurization event that could occur in the corresponding temperature region while mitigated by an applicable relief valve. )Vhen applied to Appendix G P/T limit curves, a controlling pressure also provides a lower bound pressure limit for these curves. In other words, a controlling pressure is more limiting than the P/T limit curves above it. Therefore, no P/T limits above the controlling pressure will be exceeded during normal operation or an overpressurization event.

As far as the P/T limits below the controlling pressures are concerned, restrictions on heatup and cooldown rates (which are a part of LTOP requirements) prevent operation based on these limits.

5-2

Table 5-1 MAXIMUM INDICATED PRESSURES IN PRESSURE TRANSIENTS Single PORV Mitigating Transient PORV Setpoint Reference Temperature Max. Pressure RCP Start 350 psia T < 140~F 362 psia (pressurizer 350 psia T c-> 200~F 416 psia water-solid) 530 psia At all temperatures 542 psia 2 HPSI 5 350 psia or 530 psia At all temperatures 1040 psia 3 Charging Pumps 1 HPSI & 350 psia or 530 psia T c > 220oF 740 psia 3 Charging Pumps 350 psia or 530 psia T c< 220~F 660 psia 3 Charging Pumps 350 psia At all temperatures 362 psia 530 psia At all temperatures 542 psia Single HPSI 350 psia or 530 psia T c> 220F 545 psia Pump 350 psia T c< 140oF 460 psia NOTE: (1) Straight line interpolation between two points, i.e., 362 psia 8 140 F and 416 psia 8 200~F, provides the maximum pressure values at 140F < Tc < 200~F whenever P = 350 psia is set applicable.

(2) Straight line interpolation between two points, i.e., 545 psia 8 220~F and 460 psia 8 140~F, provides the maximum pressure values for "this transient at 140<'F < T. < 220'F, whenever P = 350 psia is applicable.

sett 5-3

5k l fill

5. 4 LIMITING'EMPERATURES Several objectives were pursued in determining the limiting temperatures.

These are:

1. Optimize heatup and cooldown rates, i.e., attempt to maintain a maximum heatup rate of 50~F/hr and a maximum cooldown rate of 100~F/hr over the entire temperature region,

2. Reduce an impact on current Technical SpeciQcations (Reference 1),

and

3. Establish a lowest possible upper-bound temperature for the PORV setpoint of 350 psia.

The limiting temperatures were determined at the intersections between the controlling pressures and appropriate P/T limit curves. Table 5-2 provides a summary of the controlling pressures, corresponding limiting transients, and limiting temperatures. The impact of the identiQed temperatures on Technical Specifications and operational limitations is addressed in the following subsection.

5-4

Table '5-2 IDENTIFICATION OF LIMITING TEMPERATURES.

Limitin Temperature 8 P/T Limit Curve*

Limiting Transient Controlling 'ressure or Parameter p sla Heatup Cooldown Maximum LTOP Temperature, (1) 2500 334~F 326oF(3) 2 HPSI & 3 Charging Pumps 1040 253~F 246~F 1- HPSI 0 3 Charging,Pumps 740 220oF(2) 660 213.F(3)

Three Charging Pumps 542 200 F(3)

PORV Realignment Temperature 542(4) 200.F(3) 545 180.F(2) col I RCP Start 390 175 F(3)

CJl 375 156~F for 75 F/hr 362 102.F(2) 125 F for. 50 F/hr 362 104~F for 40~F/hr Single HPSI Pump 545 180" F 520 196.F(3) 510 185 F for 75~F/hr 490 170oF for 50oF/hr 475 160 F 158~F for 40~F/hr 460 135~F for 40~F/hr 140"F for 30 F/hr 460 117~F for 30~F/hr 125~F for 20~F/hr 460 100 F for 20~F/hr 102~F for 10~F/hr 460 <80 F for 10 1 /hr <80 F for 0 F/hr (For the notes refer to the following page)

NOTES TO TABLE 5-2 Minimum allowable temperature so as not to exceed the applicable P/T curve pressure limit for the controlling pressure indicated.

(1) Identifies an upper bound for the region in which LTOP is required. Determined at the intersection between a safety valve setpoint of 2500 psia and an applicable P/T limit curve.

(2) For 50~F/hr.

(3) For 100~F/hr.

(4) The same value as for three charging pumps.

(5) The same value as for a single HPSI pump.

C l

I

~ i

5.5 RESULTS

LIMITING CONDITIONS FOR OPERATION The administrative and operational controls comprising the proposed LTOP system are addressed below and summarized in Subsection 2.4.

1. Both PORVs shall be aligned to the RCS in Modes 3, 4, and 5 as follows:

a.

Mode 5, at T c < 180<'F; and with the higher LTOP setpoint of 530 psia in Mode 5, at T c > 180~F, Mode 4, and Mode 3, at T c< 334oF Note: Switching from the lower setpoint to the higher setpoint is allowed at any temperature above 18O~F.

I" Mode 3, prior to reducing temperature to Tc = 334~F, and Mode 4; and with the lower LTOP setpoint of 350 psia in Mode 5.

Note: The maximum LTOP temperature of 326~F is required for cooldown (See Table 5-2).

T c = 334~F is selected for both heatup and cooldown for simplicity.

2. Heatup rates shall be limited to a maximum of:

40<'F/hr, at T < 102<'F, and 50<'F/hr, at T > 102~F c

Note: These rates apply at all times, except for the case addressed in Item 7.

7. The flow path from the RWT to the RCS via a HPSI pump shall only be established if the RCS pressure boundary integrity does not if exist, or no charging pump is operable in which case all charging pumps. shall be disabled and

a. heatup rates shall be limited to a maximum of; 10oF/hr, at c1PPoF 20oF/hr, at lppoF < T c< 117oF 30oF/hr, at 117oF < T < 135oF c

40oF/hr, at 135oF < Tc < 160oF 50oF/hr, at Tc > 160oF

b. cooldown rates shall be limited to a maximum of:

PoF/hr, T c< 102oF 10oF/hr at 102 F < Tc < 125 F 2PoF/hr 125oF < T < 140oF c

30oF/hr 140oF < T c < 158oF 4O.F/hr , at 158oF < T c < 170oF 50 F/hr at 170 F < T,c < 185 F 75oF/hr 185oF < T c < 196oF 1PPoF/hr at T c > 196oF It should be noted that the limitations listed above result from the analyses assuming a single PORV mitigation. Based on two PORVs operating simultaneously, some of the above limitations could be relaxed, as follows:

Cooldown rates (See Item 3 above) could be slightly improved starting with a rate of 75oF/hr The temperature for racking out one HPSI pump could be reduced from T c = 253 F (See Item 5 above) to Tc = 212 F 5-9

The temperature for disabling all HPSI pumps could be reduced from T = 220~F (See Item 6 above) to the temperatures c

indicated in Item 1 for alignment of the PORV setpoints, i.e.,

Tc = 180 F, during heatup, and Tc = 200 F, during cooldown.

There would be no negative impact on the heatup and cooldown rates per Items 2 and 3 above.

5-10

J 6.0

SUMMARY

OF, PROPOSED CHANGES In order to implement the proposed LTOP system the follovdng is required:

1. Modify the existing PORV circuitry to accommodate the additional PORV setpoint, and change the existing setpoint. (Refer to Subsection 2.4.1).

2. Amend the Technical SpeciQcations indicated in Subsection 2.4.3 to incorporate the changes identiQed in Subsection 2.4.2.

3. Amend the appropriate plant operating procedures to incorporate

'he changes in Technical SpeciQcations.

~ ~

6-1

7. 0 CONCLUSION The proposed LTOP system is designed in accordance with the requirements set forth in the NRC Branch Technical Position RSB 5-2 (Reference 3).

The proposed system is adequate to prevent violation of the Appendix G P/T limits during an operating period ending at 10 EFPY.

Implementation of the proposed LTOP system will not result in a reduction in the margin of safety presently afforded by Technical Specifications and will not significantly impair efficient operation.

7-1

(~g I 4

)t

(

8.0 REFERENCES

1. St.Lucie Unit 1 Technical Specifications

2. Safety Evaluation by the OfQce of Nuclear Reactor Regulation Related to Amendment No. 60 to Facility Operating License No.

DPR-67, Florida Power and Light Company, St. Lucie Unit 1, Docket No. 50-335.

3, Branch Technical Position RSB 5-2, Overpressurization Protection of Pressurized Water Reactors While Operating at Low Temperatures.

4. L-78-129, St. Lucie Unit Docket No. 50-535, Proposed Amendment to Facility Operating License DPR-67, April 13, 1978.

5. Code of Federal Regulations Part 50 Appendix G, Fracture Toughness Requirements, May 1983.

6. ASME Boiler and Pressure Vessel Code Section III, Appendix G, Protection Against Nonductile Failure.

7. Evaluation of Irradiated Capsule W-97, Combustion Engineering, Windsor, CT. TR-F-MCM-004, December 1983.

8. Final Report on the St. Lucie Unit 1 Post Cycle 5 Plant Recovery Program, Combustion Engineering, Windsor, CT. CEN-72(F)-P, February 1984 (CE-Proprietary).

9. ASME Boiler,and Pressure Vessel Code Section III, Article G-2222.

10. ASME Boiler and Pressure Vessel Code Section III, Article NB-2332.

8-1

J~

l

11. Evaluation of Pressurized Thermal Shock Effects Due to Small Break LOCA with Loss of Feedwater for the Combustion Engineering NSSS, CEN 189, December 1981.

12. Draft Regulatory Guide 1.99 Revision 02, Radiation Damage to Reactor Vessel Materials.

13. St. Lucie Plant Unit No. 1, Updated Final Safety Analysis Report.

14. Dresser PORV Qualification Test, Nyle Test Report No. 43781-02, March 9, 1980.

8-2

PIGU RES t

.r 4*l A4 t~ 'h I

Q~

J J

C

OX I OT O TH E CENT I I4ET EA IO X RSCM ICKttff EL 0 CSS rO ru s<< <<M SS e 's a 46 1513

[u aC Paid

".I; <<I' t<<t I'It ll:I ii ll s, I Ill "I I!

~

I. +jl. s :lt

~

t~ sI<<l ts I II ::tl>> tl ~

,j :I  :;!F1: t s

I. I ~

II:i'. ~ I ~

s

~ ~ ~

I[.;. ~ ~

I I:ji

~

~

is s I:

~

>>Ijlt tll. I:H ;I;: i.l 'I

' I.' :.I it II

,'I:

s ~ e I

~

!ti II  : ~

'e I: I;I e.i tli'i" I~ ~ ~

~ Il :tl: II jI i>>i[ s ~

\ .".

I

'i il'l

~ ~

Ili::;:: s

II. 1".:

,". ~

[i

.I I

.: II,I

jli ,[e; s e

>>:. ', ~

~ s i' I

~ ~

ij: Ili; !i[s i I,'>>

I'[;; I>>s'.  ;>> >>I I ~

~ ~  : I".:I ts ill

'I"

~

[,I: It

.I ~ e ~

'.;:I:

j 'I' s I "'>>li ii:i >>I'.WI tits

'.[i [:[.i'. ~ ~

I[>>i I:: 'lt II[

it[ e

)lj ij::[ e e

e  :[e'I e

I~~

l[ I: jl ;II'Ii.'eljj ~ s e ~ .I ~ i<< ~ I s s

I: ll: i((i I t i I

>>['i III[ ', s,'[ I>>

II ~

ll; 'll>> ~

i[i [t;i li'

, ii 'l s

eep@Rxf i>>>>l I I '!i'el:

>>>>!I Its I I;j, j

I Ii I ill $ ~ Ii[ III II

,e I I<<I!

jI!I lit[ .'jil Iii e ~

wI Il; I jll Ij[ II i'I ll jli I

I I >>[I

~ I IIII  :[

II

[ii j X ll e ~ jl I I

'I li  !

[j 1'Ii j l[l e

I 0 ;I s

I ((l II .Is  !

~

p I

I I I Ii ~ ~

0 li j[ ij I, s

i'j

~

I l

I e

! 'll I j s

II<< s  !

[

II I

~

I

~ :I i

I I'I

'I I

j,'

0 s

<>II, I j' I

([

<<el ~

tlsl li I I!I [I [I I ~

II>>',. I tjt >>

l' i) li I

I Ij i[I: [j I[ ~

ij j!l .III sj I'[

t rr. Iji.I ~

t

l I~ I-I'

'."-.I >>>>ll I>>

I ~

'ttt III

~ ~

s ~ I et ~

I.'

ljlt si '>>I I'.

[II[ s I s[l s I: ~

~

I" I:

I >>'Iii

>>':I I.I I I ts

>>;I s il: I:I

~

.~ I e s s I ee ii:I

~

.>>ii libel s j ll I>> s Iss ill ~

~

st;3 te

~ ~

'l T

$ 'l I L4

(

5t qC Y;

4 t

'F

>A I

Zsoo

.. ~ ~ ~ ~ -- ~ ...

/ ~

4 ~ ~ ~

~ ~

~ ~ ~ ~ ~ ~ ~~

I ~

I ~

~ ~ ~

~ ~ ~ ~

~ ~

~ ~

~,

Xy o~

~ ~ - ~ ~

~ ~

lÃ,.

~ ~ ~ ~

A-3

, f~oiw<co RC,S RNPER>~<K ~c. >

F

P

4 tt FIGURE 4-1 RCP START TRANSIENTS ONEPORVM T GATING~4 s-p 30 F Tc 140 F 450

= 465 PSIA '

PppFN

~ H t ~~

~ ~

400 K

D

~t CL Pp PEN 400 PSI A N ~~

K rb.-

D.

350 t ~

.=..-;. Pp PEN = 360 PSIA

~ I ~ I ~ I .I"- 't

""="='.

~ 'OPEN=3 20 t >> t ~

PS IA--

==.-i.==P~-

~ ~ ~ I

~ ~

~

300 0' 4 8 12 . 16 20 ELAPSED TIME, SEC A-4

e N

'L lg

~w 1

\,

v

~

'IGURE RCP START TRANSIENTS ONE PORV MITIGATING,its-p 30 F Tc 4-2 200 F 450 POPEN = 465 PSIA

~ C

~ >>

P

~.

~ ~ ~ ~ ~

P 400 PSIA 'PEN

~ *

~ I

= 360 PSIA,': =;

POPEN 400 - ~

~ ~

~ ~ ~

~

tI ~~

~ ~1 ~

~ ~

~ ~ ~ ~ ~

~~

~ ~ =-I--= POP EN =32 0 PSIA

~.

350 4 ~

~

~ ~

~ t 0 ~ ~

~1

~ ~

- ~

't 3 00 0 4 8 12 16 20 24 28 ELAPSED TIME, SEC A-5

0~

'1 1

4t 0 I

S; I

I

'5 H

V ro W~

tf

FIGURE 4-3 PEAK PRESSURES IN RCP. START TRANSIENTS ONE PORV MITIGATING,hts.p 30 F 600 ~ I ~

i. -.*

~ ~ * ~

:II: i

~ ~

~ t ~

CO

~ ~ ~

.I,

~ ~ ~

500 l ~

~ ~ ~ e ~ ~~ ~ ~

~ ~

=-'

Ct: = 200 OF ~ ~0 C

N ~ << ~ ~ ~

K ~

~

>>~ ~ ~ -t. It- ~ ~

- ~

400 --- ~:--':i

-~ t hC

~ ~

• ~ ~'

TC <40'F ~ ~

~ ~

~~ ~

E" ~ ~

3003 00 400 500 600 PORV OPENING PRESSURE, PSIA

THIS FIGURE HAS BEEN DELETED A-7

4 t

a ~

a

~ \

l

~  % t

~%

FIGURE 4-5 MASS INPUTS VS. PRESSURIZER PRESSURE

'1200 alii ~ I ~

~ >>

~ ~ I 1000

=.i!:i.ii '-.=

.'-:I::::; ='I:

CO 800 +

I' I

~

IX ~ ~ ~ ~ ~ ~ ~ ~~ .

D

~ ~ ~

K -~

600 K ~

• LLI N I ' ~ ~

~

I t--I:-i'-it--"

~- ~ '

I*

aoo

~ ~ ~ '

'.'2 -3;, ' -.' -5 ',-: 6 I,j. ~"

i 200

"- NOTE: CURVE NUMBERS DEFINED ON FOLLOWING PAGE

~ ~

.= 'l:: " I.

I

"- I

. I I:

'::, '--,'-'-.'i".-:: I"'! -. "!:.= :-'i=.'

200 400 600 800 1000 1200 1400 1600 FLOW RATE, GPM

DEFINITIONS OF CURVES IN FIGURE 4-5 1 3 CHARGING PUMPS, 0.6/o DECAY HEAT 2 3 CHARGING PUMPS, 0.8/ DECAY HEAT 3 1 HPSI PUMP (NOMINAL FLOW),'0.6/o DECAY HEAT 4 1 HPSI PUMP (NOMINAL FLOW), 0.8'/o DECAY HEAT 5 "1 HPSI PUMP (NOMINALFLOW) AND 3 CHARGING PUMPS, 0.8/o DECAY HEAT 6 1 HPSI PUMP (NOMINALFLOW) AND 3 CHARGING PUMPS, 1/o DECAY HEAT 7 2 HPSI PUMPS (MAXIMUMFLOW) AND 3 CHARGING PUMPS, 1/o DECAY HEAT NOTE: EACH CURVE CONTAINS A FLOW RATE BASED ON PRESSURIZER HEATER CAPACITY OF 1500 Kw

~ e'

~ ~

4~

>>1 r,

f 0

FIGURE 4-6 DISCHARGE COEFFICIENT FOR DRESSER PORV, PART No. 31533VX-30 FOR USE IN BERNOULLI EQUATION FOR A LIQUID FLOW WITH VARYING SUBCOOLING AT THE PORV INLET 0.6 z

I 0.4 LL LL ILI oO . 0.3 LLl U

0.2 O

x 0.1 0 20 40 60 80 100 120 AT - LIQUID SUBCOOLING AT PORV INLET oF SOURCE: DRESSER PORV QUALIFICATIONTEST, WYLE TEST REPORT No. 43781-02, MARCH 9, 1980.

A-10

~ 1 ~ L I

FIGURE 5-1 ST. LUCIE UNIT 1, 10 EFPY MAXIMUMALLOWABLECOOLDOWN RATES

~ ~

100 80 X

~ h 0

60 o

Z

~ ~ ~

O O

O 40 0

CD 20 ~~~

~ ~ ~ ~ ~ ~

Ih

~ ~

- ~ -t ~ h

~ t~

~ t 0

80 100 120 140 160 180 200 Tc'NDICATED REACTOR COOLANT TEMPERATURE oF NOTE: A MAXIMUMCOOLDOWN RATE OF 100oF/HR IS ALLOWED AT ANY TEMPERATURE ABOVE 175oF

~r