ML20137L081

Rev 1 to JPN-PSL-SENP-95-025, Engineering Evaluation,Plant Operation at 2225 Psia Nominal Operating Pressure

ML20137L081
Person / Time
Site:	Saint Lucie
Issue date:	10/10/1995
From:	FLORIDA POWER & LIGHT CO.
To:
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References
FOIA-96-485 JPN-PSL-SENP-95, JPN-PSL-SENP-95-025, JPN-PSL-SENP-95-25, NUDOCS 9704070151
Download: ML20137L081 (6)

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i RNGINEERING EVALUATION i

PLANT OPERATION AT 2225 PSIA NOMINAL OPERATING PRES 8URE l

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ST LUCIE NUCLEAR PLANT UNIT 1 JPN-PSL-5ENP-95-025 i

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JPN-PSL-SENP-95-025

[I REVISION 1 pAGE 3 0F 6 f

1.0 PURPOFE AND DESCRIPTION i

' This evaluation documents an assessment of. the effects of plant operation at 2225 psia nominal RCS pressure.

Plant operation isl typically at a nominal 2250 psia.

This evaluation concludes that plant operation at 2225 psia is within the limits and analyses of the l

echnical specifications, FSAR and plant procedures, and therefore, is l

acceptable for normal operation and accident conditions.

l In addition, plant operation at 2225 psia does not require changes tol the technical specifications, is not a change to the plant as described in the FSAR, and does not require changes to plant procedures as described in the FSAR, and therefore, does not require a 50.59 safety evaluation nor NRC approval.

Revision 0 documented the acceptability of plant operation at 2235 psia nominal RCS pressui*e.

Revision 1

is issued to document the acceptability of plant operation down to the technical specification minimum value of 2225 paia.

2.0 TECEMICAL SPECIFICATIONS I

The technical specifications have been reviewed and operation at 2225 psia nominal RCS pressure is allowed.

Igehnical Snecificat_ ion, f2.1.1)

The reactor core safety limit technical specification describes that for combinations of THERMAL POWER, pressurizar pressure and maximum cold leg coolant temperature shall not exceed the limits shown on Figure 2.1-1 of the specification.

The limits of the curve prevent overheating and the onset of DNB.

The RPS in, combination with the Limiting Conditions of operation (LCO) is designed to prevent any anticipated combination of transient conditions for reactor coolant system temperature, pressure, and thermal power level that would result in a DNBR of less than the DNBR limit and preclude the existence of flow instabilities.

Therefore, operating within the LCO limits for DNB parameters assures power operation within the safety limits.

Plant operation at a pressure of 2225 psia does not adversely affect safe plant operation or safety l and is within the DNB parameters LCo.

Technical _somelfication. (3/4.2.5)

The DNB parameters technical s requires that cold leg temperature, pressurizer pressure,pecification RCS total flow rate, and axial shape index be maintained within limits..

plant operation at a pressure of 2225 psia is within the pressurizer pressure limit of 2 2225 psia.

Therefore, plant operation at a pressure of 2225 psia does not adversely affect safe plant operation or safety and is within the DNB parameters LCo.

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REVISION 1

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PAGE 4 OF 6 i

I The limits on the DNB related parameters assure that each of the l

parametere are maintained within the normal steady state envelope of j;

operation assumed in the transient and accident analyses.

l Taehnical specification. (5.4.11 i

4 The design features specification for RCS design pressure and temperature is not affected by plant operation at a pressure of 2225 l psia. All assumptions for design cyclic or transient limits remain valid.

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l 3.0 EA&R The FSAR has been reviewed The FSAR analyses support a nominal RCS pressure l and operation at 2225 psia nominal RCS i

l pressure is allowed.

1 of 2225 psia for both normal operation and accident conditions.

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i Nominal Reactor Coolant System (RCS) pressure during steady state

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conditions as described in various FSAR sections (Sections 1.3, 4.2, j'

4.4, S.1, 5.5, and 9.3) is 2250 psia.

FSAR Table 4.4-1 (pg. 4.4-40) provides RCS plant thermal 1 hydraulic design parameters for nominal l

(steady state)and design conditions:

Nominal (Steady State)

Design Conditions l

Pressure, psia 2250 2250 i 50 4.0 RCS TEMPERATURE AND PRESSURE The reduction in RCS pressure from 2250 psia to 2225 psia would havel minimal effect on the RCS temperature.

For the range of current temperaturesfTSoe, T,.w) the effect on RCS oT has been estimated to be less than 0.1 F.

With the minimal effect on the primary temperatures, the, secondary conditions would remain unchanged.

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2 5.0 ACCIDENT ANALYSES MM#

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reduction of~the norma.

per& ting pressurizer pressure from 2250 psia 4

a to 2225 psia does not Affae*

+ha.rsan t'h=ntar is analyses.x Tn

==rety KM1yses supports nt operation in the pressurizer preiisure range of l 2225 psia to 22 psia.

The value of 2225 psia corresponds to the Specification limitjar_the___ reactor _ coolant system current Technic pressuia./ Plant operation at 2225 psia, therefore, does not exceed anyl safety _ limits.

Revision 1 to this evaluation addresses operation at the technical specification limit of 2225 psia.

The uncertainties used in the UFSAR accident analyses were reviewed and compared with the uncertainties of the instruments used for technical specification compliance.

The accident analyses assumes an instrument uncertainty of 122 psi (Ref 10).

The four instruments averaged (PI-1102 A,B,C & D) have an uncertainty of 14.2 psi (i.e., 24.55//3) assuming a minimum of three operable channels (Ref 6 & 11).

Therefore, the uncertainty of the instruments used for

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]j JPN-PSL-SENP-95-025 REVISION 1

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l monitoring primary pressure is within the uncertainty assumed in the accident analyses.

The technical specification surveillance of i

l pressurizer pressure is normally via Sigma indicators on the RTGB.

However, to ensure plant operation in compliance with the technical 4

i specification limit, the ERDADS display of pressurizer pressure from the P-1102 A, B,

C & D instrument loops (average of 2 3 loops) may be used to verify pressure.

This digital computer based system provides j

increased resolution over the analog Sigma meters.

C.0 SETPOIMT AM1 LYSES Operation at 2225 psia remains within the current Technical l Specification requirements.

Protection against exceeding the Linear i

Heat Rate limit (21 kw/ft) is provided by the local power density (LPD) i LSSS and LPD LCO, which are dependent on the nuclear power peaking and j

core power level, but independent of the operating system pressure, and i

will therefore be unaffected.

The thermal margin low pressure trip (TM/LP) protects against the occurrence of DNB during steady state i

operation and for many, but not all (e.g. Loss of Flow and CEA Drop Events) Anticipated operational occurrences (A00s).

The reduction in RCs operating pressure (25 psi) will provide a reduced operating margin l to the TM/LP setpoint.

However, the TM/LP will continue to perform as i

required to provide DNB protection.

4 Similarly, the DNR LCO provides protection against DNB for transients i

involving changes in reactor coolant flow or changes in power peaking i

which do not significantly change ASI.

The~ available margin to the current LCO is dependent on the range of core operating parameters evaluated.

The lower nominal pressure affects the allowed core power as a function of ASI which is used to verify the adequacy of the current LCO for the Cycle 13 setpoint evaluation.

However, the available DNB l

LCO margin of 12.9% is more than sufficient to accommodate the lower i

nominal pressure because of the small sensitivity of DNE to RCS pressure changes.

7.0 PRESSURYSER CONTROL j

1 The present instrument loops for cor. trol of pressurizer pressure have been reviewed with respect to operating at 2225 psia. Generally, thel system design is flexible enough that control will be the same as 2250 i

psia.

The proportional heaters and spray control will be modulated to maintain the operator selected setting.

The backup heaters are energized at 2200 psia (decreasing) which is sufficiently below the 2225 psia operating setting to preclude spurious actuation and unnecessary l q

cycling.

The Techaical Specification limit for minimum pressurizer pressure is 2225 psia.

The operator is required to verify that they are at or abovel j

this setting at least once per 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />.

Since the operating setting is reduced, care must be taken in verifying that pressurizer pressure channels (PT-1102A, B,

C, and D)

Specification limit.

are in compliance with the Technical l

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JPN-PEL-SENP-95-025 REVISION 1 I

PAGE 6 OF 6 i

j The-effect of operating at the lower pressure on the scaling calculations for pressurizer pressure and pressurizer level has been l.

reviewed.

The effect of the lower pressure on the specific volumes is insignificant und thus will have minimal impact on the results of the calculations.

j s.o prauer mustnicTroms i

None l-J 90 mRFERENCES l

l 1.

St. Lucie Unit 1 Technical Specifications, Amendnient No. 138 i

2.

St. Lucie Unit l'FSAR, through Amendment No. 14 l

3.

St. Lucie Unit 1 Safety Evaluation Report (SER) and supplements 1

& 2.

l I

4.

System Description SD9-Rev.1 - Pressurizer Pressure and Level control.

i 5.

PSL 1 Control Wiring Diagrams t

8770-B-327 Sh. 97 Rev. 14 8770-B-327 Sh. 98 Rov. 11 i

8770-B-327 sh. 124 Rev. 8 8770-B-327 Sh. 125 Rev. 7 8770-B-327 Sh. 126 Rev. 7 8770-B-327 Sh. 127 Rev. 7 l.

8770-B-327 Sh. 128 Rev. 7 8770-B-327 Sh. 129 Rev. 7 i

8770-B-327 Sh. 130 Rev. 15 8770-B-327 Sh. 372 Rev. 15 i

8770-B-327 Sh. 381 Rev. 16 8770-B-327 Sh. 382 Rev. 16 j

8770-B-327 Sh. 383 Rev. 12 8770-B-327 sh. 384 Rev. 12 l

6.

Calculation PSL-1FJI-92-013 Rev. 1 dated 8/7/92 - St. Lucie Unit t

1 Pressuriser Pressure and Hot and Cold Leg Temperature Instrument Uncertainties During Normal Operation.

7.

Calculation PSL-1FJI-93-008 Rev.1 dated 7/23/93 - St. Lucie Unit i

1 RPS/SIAS Pressurizer Pressure Uncertainty Determination (P-

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1102A, B, C, D).

i 8.

Calculation 19367-ICE-0612-00 Rev. O dated 1/7/79 - Pressurizer i

Level Measurement.

9.

PSL 1 Setpoint List 8770-B-470 Rev. 13.

10.

PC/M 054-194, Cycle 13 Fuel Reload.

11.

St. Lucie Operating Procedure 1-0110057, Rev. 17, Periodic j

Surveillance of DNB Margin.

i

.l

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