ML20071N672

Proposed Tech Specs Expanding Operating Region of Power/Flow Map & Providing Associated Changes in Average Power Range Monitor Flux Scram & Rod Block Trip Settings

ML20071N672
Person / Time
Site:	Pilgrim
Issue date:	05/31/1983
From:	BOSTON EDISON CO.
To:
Shared Package
ML20071N666	List: ML20071N665 ML20071N672 ML20071N682
References
NUDOCS 8306070170
Download: ML20071N672 (11)

Text

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I Proposed Technical Specification Change Proposed Change Reference is made to Pilgrim Station Operating 1.icense No. DPR-35, Sections 2.1. A1.a, 2.1.B, 2.1.1, Bases for 2.1. A, Figure 2.1.3, Table 3.2.C, and Figure 3.11-9. The following pages are affected: 6, 7, 8, 9, 15, 21, 54, and 205H.

Currently, Section 2.1. A.1.a contains the following:

S < .65W + 55% 2 loop and S

< (.65W + 55%) FRP 2 loop EPD The desired revision shall state:

S <

.58W + 62% 2 loop and S

< (.58W + 62%) FRP 2 loop E PD

Currently, Section 2.1.B contains the following

SRB 1 0.65W + 42% 2 loop and SRB -

< (0.65W + 42%) FRP 2 loop WTPD The desired revisions shall state:

SRB 1 0.58W + 50% 2 loop and SRB -

< (0.58W + 50%) FRP 2 loop EPD Figure 2.1.1 is to be replaced with the revised 2.1.1 attached to this submittal.

l The second sentence of paragraph 2 of the bases section contained on page 15 shall be deleted. The subject of that sentence, Figure 2.1.3 on page 21, is to be deleted because it duplicates Figure 3.11-9.

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8306070170 830531

! PDR ADOCK 05000293 P PDR

Currently, Table 3.2.C states:

INSTRUMENT TRIP LEVEL SETTING  ;

APRM Upscale (Flow Biased) (0.65W + 42%) FRP ~(2) 15TPD The revision shall state:

INSTRUMENT TRIP LEVEL SETTING APRM Upscale (Flow Biased) (0.58W + 50%) FRP (2)

WLko The Figure 3.11-9, which is on page 205H, shall be replaced with Figure 3.11-9 attached to this submittal.

Reason for Change This submittal expands the operating region of Pilgrim's power / flow map, and provides associated changes in the APRM flux scram and APRM rod block trip settings.

These proposec' changes will have significant impact on the Pilgrim station opera-tional flexibility, especially during high-power /high-flow operations. Speci-fica 11y, these changes will pemit a much speedier return to full power following a brief power reduction, such as condenser backwashing, without violating PCIOMRs.

This improved power ascension capability will enable the Pilgrim Station to achieve higher capacity factors for the current and future cycles.

Safety Considerations and Significant Hazards Consideration Analysis These changes are supported by NED0-22198, which is the Extended Load Line Limit Analysis (ELLLA) performed by General Electric for Boston Edison.

This document demonstrated that the results of the limiting transients for the

limiting point in the extended operating region (100% power, 87% flow) are less severe than the same transients for the ifcense basis point (100% power,100%

flow) . The overpressure protection analysis results are also less severe for the

! (100,87) point. The stability results are the same as those reported in the Cycle 6 reload license submittal of September,1982, Y1003J01A28 and the MAPLHGR results are unchanged by the extended operating region. Therefore, it is con-

cluded that all safety bases for the extended operating region are bounded by the license basis condition and that operating in the extended operating region is j justified .

I Please note, however, that these proposed changes will affect the previous request for Technical Specification changes concerning Pilgrim station single loop opera-l tion, which were submitted to NRC by letter on May 12, 1981. Those affects will i be provided to the NRC in the near future via an update to the Single Loop request.

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We believe that this change does not present a significant hazard as defined in 10CFR50.92(c), in that it does not involve a significant increase in the prob-ability or consequence of an accident previously evaluated, does not ~ create an accident different from those previously evaluated, nor does it involve a sig-nificant reduction in a safety margin.

This change has been reviewed and approved by the Operations Review Committee, and reviewed by the Nuclear Safety Review and Audit Committee.

Schedule of Change This change will be put into effect upon Boston Edison's receipt of approval by the Commission.

Fee Determination Pursuant to 10CFR 170.12, Boston Edison proposes this change as a Class III.

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1.1 SAFETY LIMIT 2.1 LIMITING SAFETY SYSTEM SETTING 1.1 FUEL CLADDING INTEGRITY 2.1 FUEL CLADDING INTEGRITY Applicability:

. Applicability:

Applies to the interrelated Applies to trip settings of the variables associated with fuel instruments and devices which are thermal behavior. provided to prevent the reactor

- system safety limits from being exceeded.

Objective: Objective:

To establish limits below which To define the level of the pro-the integrity of the fuel clad-ding is preserved. cess variables at which automatic protective action is initiated to prevent the fuel cladding inte-grity safety limits from being exceeded.

{ Specification: Specification:

A. Reactor Pressure >800 psia and A. Neutron Flux Scram Core Flow >10% of Rated The existence of a minimum The limiting safety system trip critical power ratio (MCPR) settings shall be as specified less than 1.07 shall consti- below:

tute violation of the fuel cladding integrity safety 1. Neutron Flux Trip Settinas limit. A MCPR of 1.07 is here-inafter referred to as the a. APRM Flux Scram Trip Safety Limit MCPR.

Settina (Run Mode)

B. Core Thermal Power Limit (Reac- When the Mode Switch is tor Pressure 5800 psia and/or in the RUN position, Core Flow $10%) the APRM flux scram trip setting shall be:

When the reactor pressure is 5 800 psia or core flow is less S 5.58W + 62% 2 loop than or equal to 10% of rated, the steady state core thermal Where:

power shall not exceed 25% of design thermal power. S= Setting in percent of rated thermal C. Power Transient power (1998 MWt)

The safety limit shall be as- W= Percent of drive sumed to be exceeded when scram flow to produce a is known to have been accomplished rated core flow of by a means other than the expected 69 M lb/hr.

scram signal unless analyses demon-strate that the fuel cladding integrity safety limits defined in Specifications 1.1A and 1.1B were not exceeded during the actual transient.

Amen h t No. 6

1.1 SAFETY LIMIT 2.1 LIMITING SAFETY SYSTEM SETTING D. Whenever the reactor is in the In the event of operation with a cold shutdown condition with maximum fraction of limiting power irradiated fuel in the reactor density (MFLPD) greater than the

, vessel, the water level shall fraction of rated power (FRP), the not be less than 12 in. above

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setting shall be modified as the top of the normal active follows:

fuel zone.

- FRP "

S 5 (0.58W + 62%) MFLPD 2 Loop Where.

FRP = fraction of rated thermal power (1998 MWt)

MFLPD = maximum fraction of limit-ing power density where the limiting power density is 13.4 KW/ft for 8x8 and P8x8R fuel.

The ratio of FRP to MFLPD shall be set equal to 1.0 unless the actual operating value is less than the design value of 1.0, in which case the actual operating value will be used.

For no combination of loop recirc-ulation flow rate and core thermal power shall the APRM flux scram trip setting be allowed to exceed 120% of rated thermal power.

b. APRM Flux Scram Trip Setting (Refuel or Start and Hot Standby Mode)

When the reactor mode switch is in the REFUEL or STARTUP position, the APRM scram shall be set at less than or equal to 15% of rated power.

c. IRM The IRM flux scram setting shall be 5120/125 of scale.

B. APRM Rod Block Trip Setting The APRM rod block trip setting l

shall be:

S RB I 0. 58W + 50% 2 Loop Amendment No. 7

4 1.1 SAFETY LIMIT 2.1 LIMITING SAFETY SYSTEM SETTING Where, E

RB = Rod block setting in per-cent of rated thermal power (1998 MWt)

W = Percent of drive flow re-quired to produce a rated core flow of 69M lb/hr.

In the event of operating with a maximum fraction limiting power density (MFLPD) greater than the fraction of rated power (FRP),

the setting shall be modified as follows:

FRP S

g 5 (O. 58W + 50%) MFLPD 2 Loop Where, FRP = fraction of rated thermal power MFLPD = m&ximum fraction of limit-ing power density where the limiting power density is 13.4 KW/ft for 8x8 and P8x8R fuel.

The ratio of FRP to MFLPD shall be set equal to 1.0 unless the actual operating value is less than the design value of 1.0, in which case the actual operating value will be used.

C. Reactor low water level scram setting shall be 2 9 in. on level instruments.

D. Turbine stop valve closure scram settings shall be 510 percent valve closure.

E. Turbine control valve fast clo-sure setting shall be 2150 psig

, control oil pressure at accele-ration relay.

F. Condenser low vacuum scram set-ting shall be 2 23 in. Hg. vacuum.

G. Main steam isolation scram setting shall be 1 10 percent valve closure.

Amendment No. 8

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• 2 When in the refuel or startup/ hot standbv -

l30 ' modes, the APRM scram shall be set at 6 15% of design power -

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0 20, 40 60 80 .. 100 120 E Recirc.ulation Fl.o.w (% of Des 10n)

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Figure 2.1.1

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.=::.- APRM Scram and Rod Block Trip Limiting Safety System Settings

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2.1 BASES

In s m ry:

1. The abnormal operational transients were analyzed to a power level of 1998 MWt.

11. The licensed maximum power level is 1998 MWt.

iii. Analyses of transients esaploy adequately conservative values of the controlling reactor parameters.

iv. The analytical procedures now used result in a more logical answer than the alternative method of assuming a higher starting power in

conjunction with the expected values for the parameters.

The bases for individual set points are discussed below:

A. Neutron Flux Scram Trip Settinas APRM The average power range monitoring (APRM) system, which is cali-brated using heat balance data taken during steady-state conditions, reads in percent of design power (1998 MWt). Because fission cham-1 bers provide the basic input signals, the APRM system responds directly to average neutron flux. During transients, the instan-taneous rate of heat transfer from the fuel (reactor thermal power) is less than the instantaneous neutron flux due to the time constant of the fuel. Therefore, during abnormal operational transients, the thermal power of the fuel will be less than that indicated by the neutron flux at the scram setting. Analyses demonstrated that with a 120 percent scram trip setting, none of the abnormal operational transients analyzed violate the fuel safety limit and there is a substantial margin from fuel damage. Therefore, the use of flow referenced scram trip provides even additional margin.

The flow biased scram plottei on Figure 2.1.1 is based on recircula-tion loop flow.

An increase in the APRM scram setting would decrease the margin pre-sent before the fuel cladding integrity safety limit is reached.

The APRM scram setting was determined by an analysis of margins re-quired to provide a reasonable range for maneuvering during opera-tion. Reducing this operating margin would increase the frequency J of spurious scrams, which have an adverse effect on reactor safety because of the resulting thermal stresses. Thus, the A*RM setting was selected because it provides adquate margin for the fuel clad-ding integrity safety limit yet allows operating margin that reduces

[ the possibility of unnecessary scrams.

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Amendment No. 15

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PNPS TABLE 3.2.C

. INSTRUMENTATION THAT INITIATES ROD BLOCKS Minimum f af Operable Instrument Channels Per Trip Systems (1) Instrument Trip Level Setting 2 APRM Upscale (Flow (0.58W + 50%) FRP (2)

Biased) MFLPD 2 APRM Downscale 2.5 indicated on scale 1 (7) Rod Block Monitor (0.65W + 42%) FRP (2)

(Flow Biased) MFLPD 1 (7) Rod Block Monitor 5/125 of full scale Downscale 3

IRM Downscale (3) 5/125 of full scale 3 IRM Detector not in (8)

Startup Position 3 IRM Upscale 5108/125 of full scale 2 (5) SRM Detector not in (4)

Startup Position 2 (5) (6) SRM Upscale 5 5 10 counts /sec.

1.(9) Scram Discharge Volume 518 gallons Water Level-High Amendmend No.

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