ML20092A633

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Proposed Tech Specs,Revising Main Steam Safety Valve Setpoints & Max Allowable Power Range Neutron Flux High Setpoints W/Inoperable Main Steam Safety Valves
ML20092A633
Person / Time
Site: Seabrook NextEra Energy icon.png
Issue date: 09/05/1995
From:
NORTH ATLANTIC ENERGY SERVICE CORP. (NAESCO)
To:
Shared Package
ML20092A613 List:
References
NUDOCS 9509110116
Download: ML20092A633 (11)
v • d • e


Text

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TABLE 3.7-1 L'- <-

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MAXIMUM ALLOWABLE POWER RANGE NEUTRON FLUX HIGH SETPOINT WITH IN0PERABLE STEAM LINE SAFETY VALVES DURING FOUR-LOOP OPERATION MAXIMUM NUMBER OF INOPERABLE MAXIMUM ALLOWABLE POWER RANGE SAFETY VALVES ON ANY NEUTRON FLUX HIGH SETPOINT OPERATING STEAM GENERATOR (PERCENT OF RATED THERMAL POWER) v n

1 47 66 2

3 e 97 M L8 TABLE 3.7-2

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STEAM LINE SAFETY VALVES PER LOOP VALVE NUMBER Loop 1 Loop 2 Loop 3 Loop 4 LIFT SETTING * (* 3%)** ORIFICE SIZE

[

V6 V22 V36 V50 185 psig 16.0 sq. in.

~) V7 V23 V37 VS1 il sig 16.0 sq. in.

V8 V24 V38 V52 81cf -1330 psig 16.0 sq. in.

V9 V25 V39 V53 8116 4336 sig 16.0 sq. in.

V10 V26 V40 V54 1125 4355 psig 16.0 sq. in.

"The lift setting pressure shall correspond to ambient conditions of the valve at nominal operating temperature and pressure.

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i SEABROOK - UNIT 1 3/4 7-2 Amendment No.15  ;

9509110116 950905 .

PDR ADOCK 05000443

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1 3/4.7 PLANT SYSTEMS _

BASES 3/4.7.1 TURBINE CYCLE 3/4.7.1.1 SAFETY VALVES The OPERABILITY of the main steam line Code safety valves ensures that the Secondary. System pressure will be limited to within 110% (1320 psia) of its design pressure of 1200 pila during the most severs anticipated system operational transient. The maximum relieving capacity is associated with a Turbine trip from 100% RATED THERMAL POWER coincident with an assumed loss of condenserheatsink(i.e.,nosteambypasstothecondenser).

The specified valve lift settings and relieving capaci es are in accor-dance with the requirements of Section III of the ASME Boi er and Pressure Code, (1974 Edition, including the Summer 1975 Addenda). The total relieving capac for all valves on all of the steam lines is 1. , 107 lbs/hr which

^1 s 1 of the total secondary steam flow of 1.514 x 107 O THE s/hr at 100% RATED POWER. A minimum of tc., CPERABLE safety valvas par steam ganarator ensures that sufficient relieving capacity is available for the allowable THERMAL POWER restriction in Table 3.7-1.

STARTUP and/or POWER OPERATION is allowable with safety valves inoperable within the limitations of the ACTION requirements on the basis of the reduction in Secondary Coolant System steam flow and THERMAL POWER required by the reduced Reactor trip settings of the Power Range Neutron Flux channels. The k.) Reactor Trip Satpoint reductions are derived on the following bases:

For four loop operation:

\ ,m ,m ....

">' x 109 -

SP = '^' ~X

, Where:

N, SP = Reduce eactor Trip Satpoint in percen RATED THERMAL g POWER, to V = Maximum number o operabl afety valves per steam line, 109 = Power Range Neutron ux- h Trip Satpoint for four loop h operation, b X = Total sving capacity of all safe valves per steam li n 1bs/hr, and

= Maxistura relieving capacity of any ons safety va. - in lbs/hr

% N j

SEABROOK - UNIT 1 B 3/4 7-1 Amendment No.15

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, INSERT "B 3/4.7.1.1" Hi o = (100/0,,te)*(W,*hr,*N/K - Occ,)

where: i Hi o = Safety Analysis power range high neutron flux setpoint, percent of RATED THERMAL POWER Q,,1w = RATED THERMAL POWER, Mwt Orc,= Reactor coolant pump heat Mwt K = Conversion factor, 3.412x10 6(Btu /hr)/Hwt hr, = heat of vaporization for steam at 110% of the Secondary System design pressure, Btu /lbm i

N = Number of loops in the plant W, = Minimum total steam flow rate, lbm/hr, of the operable MSSVs on ,

any one steam generator at the MSSV inlet pressure which assures all Secondary System pressures are no greater than 110% of design.

The steam flow rate through each operable MSSV is calculated with ,

consideration of 1) opening setpoint with allowance for as-found setpoint ,

tolerance, 2) accumulation, and 3) inlet pressure. For example, if the l maximum number of inoperable MSSVs on any one steam generator is one, then W, i is a summation of the calculated flow though each MSSV at the appropriate  !

valve inlet pressure, excluding the MSSV with the highest flow. If the maximum number of inoperable MSSVs per steam generator is three, then W, is a summation of the calculated flow through each MSSV at the appropriate valve inlet pressure, excluding the three MSSVs with the highest flows. The  !

following plant specific safety valve flow rates were used:

SG Safety Main Steam System Valve Number (Bank No.) Set Pressure (psia) Flow (lbm/hr per loop) 1 1200 893.160 2 1210 900,607 3 1220 908,055 4 1230 915,502 5 1240 922,950 The Safety Analysis limit values of the power range high neutron flux setpoints calculated from this algorithm are adjusted lower for use in Technical Specification 3.7.1.1 to account for instrument and channel uncertainties.

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l III. RETYPE OF LAR 95-04 PROPOSED CIIANGES The enclosed retyped pages reflect the currently issued version of Technical Specifications and 13ases. Revision bars are provided in the right margin to designate a change in the text.

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TABLE 3.7-1 MAXIMUM ALLOWABLE POWER RANGE NEUTRON FLUX HIGH SETPOINT WITH INOPERABLE STEAM LINE SAFETY VALVES DURING FOUR-LOOP OPERATION MAXIMUM NUMBER OF INOPERABLE MAXIMUM ALLOWABLE POWER RANGE SAFETY VALVES ON ANY NEUTRON FLUX HIGH SETPOINT OPERATING STEAM GENERATOR (PERCENT OF RATED THERMAL POWER) 1 66 2 47 3 28 TABLE 3.7-2 STEAM LINE SAFETY VALVES PER LOOP VALVE NUMBER Looo 1 Looo 2 Loco 3 Looo 4 LIFT SETTING * ( 3%)" ORIFICE SIZE V6 V22 V36 V50 1185 psig 16.0 sq. in.

V7 V23 V37 V51 1195 psig 16.0 sq. in.

V8 V24 V38 V52 1205 psig 16.0 sq. in.

V9 V25 V39 V53 1215 psig 16.0 sq. in.

V10 V26 V40 V54 1225 psig 16.0 sq. in.

  • The lift setting pressure shall correspond to ambient conditions of the valve at nominal operating temperature and pressure.

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l SEABROOK - UNIT 1 3/4 7-2 Amendment No. M.

3/4,7 PLANT SYSTEMS BASES 3/4.7.1 TURBINE CYCLE 3/4.7.1.1 SAFETY VALVES The OPERABILITY of the main steam line Code safety valves ensures that the Secondary System pressure will be limited to within 110% (1320 psia) of its design pressure of 1200 psia during the most severe anticipated system operational transient. The maximum relieving capacity is associated with a Turbine trip from 100% RATED THERMAL POWER coincident with an assumed loss of condenser heat sink (i.e., no steam bypass to the condenser).

The specified valve lift settings and relieving capacities are in accor-dance with the requirements of Section III of the ASME Boiler and Pressure Code.

(1974 Edition. including the Summer 1985 Addenda). The total relieving capacity for all valves on all of the steam lines is 1.816 x 10' lbs/hr which is 120% of the total secondary steam flow of 1.514 x 10 lbs/hr at 100% RATED THERMAL 7

POWER. A minimum of two OPERABLE safetv valves )er steam generator ensures that sufficient relieving capacity is available for tie allowable THERMAL POWER restriction in Table 3.7-1.

STARTUP and/or POWER OPERATION is allowable with safety valves inoperable within the limitations of the ACTION requirements on the basis of the reduction in Secondary Coolant System steam flow and THERMAL POWER required by the reduced Reactor trip settings of the Power Range Neutron Flux channels. The Reactor Trip Setpoint reductions are derived on the following bases:

For four loop operations:

Hi @ = (100/0,,t,a) x $ x h; r x N) - Or,  ;

K where:

Hi $ =

Safety Analysis power range high neutron flux setpoint.

percent of RATED THERMAL POWER

=

0,,teo RATED THERMAL POWER. Mwt Org

=

Reactor coolant pump heat. Mwt K =

Conversion factor. 3.412 x 106 (Btu /hr)/Mwt  :

hr, -

heat of vaporization for steam at 110% of the Secondary System design pressure. Btu /lbm N -

Number of loops in plant W, = Minimum total steam flow rate, lbm/hr. of the operable MSSVs on any one steam generator at the MSSV inlet pressure which assures all Secondary System pressures are no greater than 110% of design.

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SEABROOK - UNIT 1 B 3/4 7-1 Amendment No. &

PLANT SYSTEMS BASFS 3/4.7.1 TURBINE CYCLE (Continued) 3/4.7.1.1 SAFETY VALVES The steam flow rate through each operable MSSV is calculated with consideration of 1) opening setpoint with allowance for as-found setpoint tolerance. 2) accumulation. and 3) inlet pressure. For example, if the maximum number of inoperable MSSVs on any one steam generator is one, then W3 is a summation of the calculated flow through each MSSV at the ap3ro3riate valve inlet pressure, excluding the MSSV with the liglest flow.

If the maximum number of inoperable MSSVs per steam ' generator is three. then W is a summation of the calcu~ ated flow throuah ~

each MSSV at the a)propriate valve inlet pressure, excluding the three MSIVs with t1e highest flows. The following plant specific safety valve flow rates were used:

SG Safety Main Steam System Valve Number (Bank No.) Set Pressure (psia) Flow (lbm/hr per loop) 1 1200 893.160 2 1210 900.607 3 1220 908.055 4 1230 915.502 5 1240 922.950 The Safety Analysis limit values of the power range high neutron flux set]oints calculated from this algorithm are adjusted lower for use in Tec1nical Specification 3.7.1.1. to account for instrument and channel uncertainties.

SEABROOK - UNIT 1 B 3/4 7-1A Amendment No. 46-

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IV. DETERMINATION OF SIGNIFICANT IIAZARDS FOR LAR 95-04 PROPOSED l CIIANGES

1. T__I

.L e proposed chances do not involve a sienificant increase in the probability or conseauences of an accident previously evaluated.

The proposed changes assure that the consequences of postulated overpressure events will remain in compliance with the Basis to Technical Speci6 cation 3.7.1.1. Specifically, the Secondary System pressure will be limited to within 110% (1320 psia) of its design pressure of 1200 psia during the most severe anticipated system operational transient. The most severe anticipated transient remains a Turbine trip from 100% Rated Thermal Power coincident with an assumed loss of condenser heat sink. No changes are made to the design or manner of operation of structures, systems or components. Therefore, the proposed changes do not involve an increase in the probability or consequences of an accident previously evaluated.

2. The proposed chances do not create the possibility of a new or different kind of accident from any accident nreviously evaluated.

As described above, the changes proposed in this LAR involve reducing the opening setpoints of the Main Steam Safety Valves (MSSVs) and reducing the maximum allowable Power Range Neutron Flux liigh Setpoints with inoperable MSSVs. These changes do not cause the associated structures, systems, or components to be operated outside their original design envelope. No changes are made to the design or manner of operation of structures, systems, or components.

No new failure mechanisms are introduced. Therefore, the proposed changes do not create the possibility of a new or different accident from any accident previously evaluated.

3. The proposed chances do not result in a sieni6 cant reduction in the marcin of safety.

The margin of safety is de6ned by: 1) the acceptance criteria for the design of associated structures, systems, or components; and 2) the acceptance criteria for previously evaluated accidents.

As previously stated, the proposed changes do not cause the associated structures, systems or components to be operated outside their original design envelope. Similarly, the proposed changes assure that the acceptance criteria for previously evaluated accidents will continue to be met. The proposed changes assure that the consequences of postulated overpressure events will remain in compliance with the Basis to Technical Specification 3.7.1.1. Speci6cally, the Secondary System pressure will be limited to within 110% (1320 psia) of its design pressure of 1200 psia during the most severe anticipated system operational transient. The most severe anticipated transient remains a Turbine trip from 100% Rated Thermal Power coincident with an assumed loss of condenser heat sink. Therefore, the proposed changes do not result in a reduction in the margin of safety.

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V. PROPOSED SCIIEDULE FOR LICENSE AMENDMENT ISSUANCE AND EFFECTIVENESS North Atlantic requests NRC review of License Amendment Request 95-04 and issuance of a license amendment by October 27,1995 having etTectiveness when the MSSV lif1 setpoints have .

been reset, approximately November 3,1995. Specifically, the new power range neutron flux trip setpoint values will become effective after all of the affected MSSV lift setpoints have been reset, which may be done on-line. During the transition from the current setpoints to the new lift setpoints, the safety analysis remains conservative for interim configurations since the lift setpoints are being reduced. Each MSSV to be reset will be declared OPERABLE after its setpoint has been reset to the new value and verified. The power range neutron flux trip setpoints currently approved by Technical Clarification will be in effect until all of the affected MSSV lift setpoints have been reset. At that time, the higher power range neutron flux trip setpoints addressed in this evaluation will become effective in the event that a MSSV becomes inoperable.

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VI. ENVIRONMENTAL, IMPACT ASSESSMENT Nonh Atlantic has reviewed the proposed license amendment against the criteria of 10CFR51.22 for environmental considerations. The proposed changes do not involve a signi6 cant hazards consideration, nor increase the types and amounts of ef6uent that may be released offsite, nor signi6cantly increase individual or cumulative occupational radiation exposures. Based on the foregoing, Nonh Atlantic concludes that the proposed change meets the criteria delineated in 10CFRS 1.22(c)(9) for a categorical exclusion from the requirements for an Environmental Impact Statement.

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