ML20245F262

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Proposed Tech Specs Re Instrumentation That Initiates Primary Containment Isolation Functions
ML20245F262
Person / Time
Site: Quad Cities  Constellation icon.png
Issue date: 08/03/1989
From:
COMMONWEALTH EDISON CO.
To:
Shared Package
ML20245F260 List:
References
NUDOCS 8908140218
Download: ML20245F262 (13)
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Text

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AIJACEMFET_t PROPOSED CHANGES TO APPENDIX A TECHNCIAL SPECIFICATIONS FOR 00AJ CITIES STATION UNITS 1 AND 2 DPR-29 DPR-30 3.2/4.2-8 3.2/4.2-6 3.2/4.2-15 3.2/4.2-6a 3.2/4.2-11 8908140218 890903 "a ADOCK 05000D54 PDR P PNU

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0223T:3

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QUAD-CITIES DPR-29 l setting of 140% o'f rated steam flow, in conjunction with the flow limiters l

and main stenmline valve closure, limits the mass inventory loss such that fuel is not uncovered, fuel temperatures remain less than 1500 F, and i release of radioactivity to the envircres is well below 10 CFR 100 guidelines i (reference SAR Sections 14.2.3.9 and 14.2.3.10).

Temperature monitoring instrumentation is provided in the main steamline tunnel to detect leaks in this area. Trips are provided on this i -instrumentation and when exceeded cause closure of Group 1 isolation

( valves. Its setting of 200 F is low enough to detect leaks of the order of 5 to 10 gpm; thus it is capable of covering the entire spectrum of breaks.

For large breaks, it is a backup to high-steam flow instrumentation discussed above, and for small breaks with the resulting small release of radioactivity, gives isolation before the guidelines'of 10 CFR 100 are

. exceed *d.

High radiation monitors in the main steamline tunnel have been provided to

. detect gross fuel failure. This instrumentation causes closure of Group 1 valves, the only valves required to close for this accident. With the established setting of 15 times normal background (without hydrogen addi-tion) and main steamline isolation valve closure, fission product release is limited so that 10 CFR 100 guidelines are not exceeded for this accident (reference SAR Section 14.2.1.7).

Pressure instrumentation is provided which trips when main steamline pressure drops-below 825 psig. A trip of this instrumentation results in closure of Group 1 isolation valves. In the Refuel and Startup/ Hot Standby aodes this trip function is bypassed. This function is provided primarily to provide protection against a pressure regulator malfunction which would cause the control and/or bypass valve to open. With the trip set at 825 psig, inventory loss is limited so that fuel is not uncovered and peak cladding temperatures are much less than 1500'F; thus, there are no fission products available for release other than those in the reactor water .

(reference SAR Section 11.2.3).

The RCIC and the HPCI high flow and temperature instrumentation are provided to detect a break in their respective piping. Tripping of this instrumentation results in actuation of the RCIC or of HPCI isolation valves. Tripping logic for this function is the same as that for the main steamline isolation valves, thus all sensors are required to be operable or in a tripped condition to meet single-failure criteria. The trip settings

,Ig p d e MEF and 300% of design flow and valve closure time are such that core uncovery is prevented and fission product release is within limits.

3.2/4.2-8 Amendment No. 114

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QUAD-CITIES i i

DPR-29 i L

i TABLE 3.2-1 INSTRUMENTATION THAT INITIATES PRIMARY CONTAINMENT ISOLATION FUNCTIONS Minimum Number of Operable or Tripped Instrument Channels [1] Instruments Trip Level Setting f Action [2] 1 4 Reactor low water [5] >144 inches above top of A active fuel

  • 4 Reactor low low water >84 inches above top of A active fuel
  • 4 High drywell pressure [5] 12.5 psig [3] A 16 High flow main steamline[5] 1140% of rated steam flow B 16 High temperature main -<200 F B steamline tunnel 4 High radiation main <15 x normal rated power B steamline tunnel [6] Eackground 4 Lowmainsteampressure[4] >825 psig B 2 High flow RCIC steamline <300% of rated steam C Tiow[7]

M4 RCIC turbine area high r20^"T C temperature sl7ov 2 High flow HPCI steamline <300% of rated steam D Ylow[7]

.c-M4 HPCI area high temperature f ^0"T D s etov Notes

[1] Whenever primary containment integrity is required, there shall be two operable or tripped systems for each function, except for low pressure main steamline which only need be available in the Run position.

3.2/4.2-15 Amendment No. 114 l

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QUAD-CITIES 1- DPR-30 Venturi tubes are provided in the main steamlines as a means of measuring-steam flow and also. limiting the loss of mass inventory from the vessel during a steamline break accident. In addition to monitoring steam flow, instrumentation is provided which causes a trip of Group 1 isolation valves. The primary function of the instrumentation is to detect a break in the m61n steamline, thus only Group 1 valves are closed. For the worst-case accident, main steamline break outside the drywell, this trip setting of 140% of rated steam flow, in conjunction with the flow limiters and main steamline valve closure, limits the mass inventory loss such that fuel is not uncovered, fuel temperatures remain less than 1500*F, and release of radioactivity to the environs is well below 10 CFR 100 guidelines (reference SAR Sections 14.2.3.9 and 14.2.3.10).

Temperature monitoring instrumentation is provided in the main steamline tunnel to detect leaks in this area. Trips are provided on this instrumentation and when exceeded cause closure of Group 1 isolation valves. Its setting of 200*F is low enough to detect leaks of.the order of 5 to 10 gpm; thus it is capable of covering the entire spectrum of breaks.

For large breaks, it is a backup to high-steam flow instrumentation discussed above, and for small breaks with the resulting small release of radioactivity, gives isolation before the guidelines of 10 CFR 100 are exceeded.

High radiation monitors in the main steamline tunnel have been provided to detect gross fuel failure. This instrumentation causes closure of Group 1 valves, the only valves required to close for this accident. With the established setting of 15 times normal background (without hydrogen addition) and main steamline isolation valve closure, fission product release is limited so that 10 CFR 100 guidelines are not exceeded for this accident (reference SAR Section 14.2.1.7).

Pressure instrumentation is provided which trips when main steamline pressure drops below 825 psig. A trip of this instrumentation results in closure of Group 1 isolation valves. In the Refuel and Startup/ Hot Standby modes this trip function is bypassed. This function is provided primarily to provide protection against a pressure regulator malfunction which would cause the control and/or bypass valve to open. With the trip set at 825 psig, inventory loss is limited so that fuel is not uncovered and peak cladding temperatures are much less than 1500*F; thus, there are no fission products available for release other than those in the reactor water (reference SAR Section 11.2.3).

l 12268/0471Z 3.2/4.2-6 Amendment No.

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.j..P i QUAD-CITIES  !

DPR-30 ,

The RCIC.and the HPCI high flow and temperature instrumentation are provided to detect a break in their respective piping. Tripping of this instrumentation results in actuation of the RCIC or of HPCI isolation valves. Tripping logic for this function is the same as that for the main steamline isolation valves, thus all sensors are required to be operable or in a tripped condition to meet single-failure criteria. The trip settings of 200'F on RCIC and 170'F on HPCI and 300% of design flow and valve closure l

time are such that core uncovery is prevented and fission product release is within limits.

The instrumentation which initiates ECCS action is arranged in a one-out-of-two taken twice logic circuit. Unlike the reactor' scram circuits, however,~there is one trip system associated with each function rather.than the two trip systems in the reactor protection system. The r single-failure criteria are met by virtue of the fact that redundant core cooling functions are provided, e.g., sprays and automatic blowdown and high-pressure coolant-injection. The specification requires that if a trip system becomes inoperable, the system which it activates is declared inoperable. For example, if the trip system for core spray A becomes inoperable, core spray A is declared inoperable and the out-of-service specifications of Specification 3.5 govern. This specification preserves the effectiveness of the system with respect to the single-failure criteria even during periods when maintenance or testing is being performed.

The control rod block functions are provided to prevent excessive control rod withdrawal so that MCPR does not go below the MCPR Fuel Cladding Integrity Safety Limit. The trip logic for this function is one out of n; e.g., any trip on one of the six APRM's, eight IRM's, four SRM's will result in a rod block. The minimum instrument channel requirements assure sufficient instrumentation to assure that.the single-failure criteria are met. The minimum instrument channel requirements for the RBM may be reduced by one for a short period of time to allow for maintenance, testing, or calibration. This time period is only - 3% of the operating time in a month and does not significantly increase the risk of preventing an

-inadvertent control red withdrawal.

12268/471Z 3.2/4.2-6a Amendment No.

4',- . QUAD-CITIES l

OPR-30

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. TABLE 3.2-1 INSTRUMENTATION THAT INITIATE $ PRIMMtY CONTAINMENT ISOLATION FUNCTIONS Mininnan Number of Operable or Tripped ne h nts Trin Level settina Actinn E 4 Reactor low water [5] >144 inches above top of A active fuel" 4 Reactor low low water 184 inches above top of A active fuel

  • 4 High'drywell pressure (Il 12.5 psig I33 A 16 High flow main steamline(5) 11407 of rated steam flow 5 16 High temperature main 1200* F B steamline tunnel 4

Highradiationmpgg 115 x normal rated power 8 steam 11ne tunnell a packground (without hydrogen addition) 4 . Low main steam pressure ("I 1825 psig B 2- High flow RCIC steamline C

'1300(})ofratedsteam flow 16 RCIC turbine area high 1200* F C temperature 2 High fluw HPCI steamline 13005 gf rated steam 0 flowi77 4 HPCI area high temperature 1170* F 0  !

E0181

1. ihenever primary containment integrity is required. there shall be two operable or tripped systems for each function. except for low pressure main steamline which only need be available in the Run position.
2. Action, if the first column cannot be met for one of the trip systems. that trip

' system shall be tripped.

If the first column cannot be met for both trip systems, the appropriate actions listed below shall be taken.

A. Initiate an orderly shutdown and have the reactor in Cold Shutdown condition in 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />.

B. Initiate an orderly load reduction and have reactor in Hot Standby within 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br />.

C. Close isolation valves in RCIC system.

O. Close isolation valves in HPCI subsystem.

3. Need not be operable when primary containment integrity is not required.

4 The isolation trip signal is bypassed when the mode switch is in Refuel or Startup/

Hot Shutdown.

5. The instrumentation also isolates the control room ventilation system.
6. This signal also autaneterally closes the mechanical vacuum pump discharge line iso-lation valves.
7. Includes a time delay of 3 i t i 9 seconds.
  • Top of active fuel is doftned as 360" above vessel zero for all water levels used in the LOCA analysis (see Bases 3.2).

07408/03382 3.2/4.2 11 Amenenent No.

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QUAD-CITIES DPR-30

-Venturi. tubes are provided in the main steamlines as a means of measuring steam flow and also limiting the loss of mass inventory from the vessel during a steamline break accident. In addition to monitoring steam flow, instrumentation is provided which causes a trip of Group 1 isolation

. valves. The primary function of the instrumentation is to detect'a break in the' main steamline, thus only Group 1 valves are closed. For the worst-case accident,' main steamline break outside the drywell, this trip setting of 1407. of rated steam flow, in conjunction with the flow limiters and main steamline valve closure, limits the mass inventory loss such that fuel is not uncovered, fuel temperatures remain less than 1500*F, and release of

. radioactivity to the environs is well below 10 CFR 100 guidelines (reference SAR Sections 14.2.3.9 and 14.2.3.10).

Temperature monitoring instrumentation is provided in the main steamline

-tunnel to detect leaks in this area. Trips are provided on this instrumentation and when exceeded cause closure of Group 1 isolation

-valves. Its setting of 200*F is low enough to detect leaks of the order of 5 to 10 gpm; thus it is capable of covering the entire spectrum of breaks.

For large breaks, it is a backup to high-steam flow instrumentation discussed above, and for small breaks with the resulting small release of radioactivity, gives isolation before the guidelines of 10 CFR 100 are exceeded.

High radiation monitors in the main steamline tunnel have been provided to detect gross fuel failure. This instrumentation causes closure of Group 1 valves, the only valves required to close for this accident. With the established setting of 15 times normal background (without hydrogen addition) and main steamline isolation valve closure, fission product release is limited so that 10 CFR 100 guidelines are not exceeded for this accident (reference S/2 Section 14.2.1.7).

Pressure instrumentation is provided which trips when main steamline pressure drops below 825 psig. A trip of this instrumentation results in closure of Group 1 isolation valves. In the Refuel and Startup/ Hot Standby modes this trip function is bypassed. This function is provided primarily to provide protection against a pressure regulator malfunction which would cause'the control and/or bypass valve to open. With the trip set at 825 psig, inventory loss is limited so that fuel is not uncoversd and peak cladding temperatures are much less than 1500*F; thus, there are no fission products available for release other than those in the reactor water (reference SAR Section 11.2.3).

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I 1226B/0471Z 3.2/4.2-6 Amendment No. '

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it" QUAD-CITIES DPR-30 L

The RCIC and.the HPCI high flow and temperature instrumentation are provided to detect a break in their respective piping. Tripping of'this

-instrumentation results in' actuation of the RCIC or of HPCI isolation 7 valves. Tripping logic _for this function is the same as that for the main steamline isolation valves, thus all sensors >Je required to be operable or in.a tripped condition to meet single-failLre criteria. The! trip settings of 170!F. and 300% of design flow and val',e closure time are such that core - l-uncovery:is prevented and fission produ'.t release is within limits.

The instrumentation which initiates EO S action is arranged in a one-out-of-two taken twice logic circuit. Unlike the reactor scram circuits, however, there is one trip system associated with each function rather than.the two. trip systems in the reactor protection system. The single-failure criteria are met by virtue of the fact that redundant core cooling functions are provided, e.g., sprays and automatic blowdown and high-pressure coolant injection. The specification requires that if a trip.

system becomes inoperable, the system which it activates is declared inoperable. For example, if~the trip system for core spray A becomes inoperable, core spray A is declared inoperable and the out-of-service

, specifications of Specification 3.5 govern. This specification preserves the effectiveness of the system with respect to the single-failure criteria even during periods.when maintenance or testing is being performed.

The control rod block functions are provided to prevent ~ excessive control rod withdrawal so that MCPR does not go below the MCPR Fuel Cladding Integrity' Safety' Limit. The trip logic for this function is one out of n; e.'g., any trip on one of the six APRM's, eight IRH's, four SRM's will result tin a rod block. The minimum instrument channel requirements assure sufficient instrumentation to assure that the single-failure criteria are met. The minimum instrument channel requirements for the RBM may be reduced by one for a'short period of time to allow for maintenance, testing, or calibration. This time period is only - 3% of the operating time in a month and does not significantly increase the risk of preventing an inadvertent control rod withdrawal.

i 1226B/471Z 3.2/4.2-6a Amendment No.

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  • QUAD-CITIES:

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  • l et TABLE 3.2 1.

INSTRUMENTATION THAT INITIATES PRIMARY CONTAINMENT ISOLATION FUNCTION $

' Minimum Number'.

.of Operable.or Tripped Instrumeptb .

Channels W Instruments Trin Level settina Action [I3 4- Reactor low water [5] >144 inches above top of- A active fuel

  • 4 E Reactor low low water 184 inches above top of- A active fuel
  • 1 4' 'High drywell pressure [5] 12.5 psig (33 A 16 High flow main steamline[5] 1140% of' rated steam flow B

.16 ' High temperature main 1200* F B steamline tunnel 4

High radiation gjg 115 x nornal rated power B steamline tunnell_J background (without hydrogen addition) 4 'LowmainsthampressureI43 2.825 'psig B

' 2 -1 High flow RCIC steamline C 1300(*I)of flow rated steam 4 RCIC turbine area high 1170* F C temperature 2 High flow HPCI steamline 13005 Qf rated steam .1 flow \li 4 'HPCI area high temperature 1170* F 0

m.
1. 'Whenever primary containment integrity is required..there shall be two aperable or tripped systems for each function, except for low pressure main steamli ne which only.

need be available-in the Run position.

2. ' Action, if the first column cannot be met for one of-the trip systems, that trip system'shall be tripped.

.If the first column cannot be met for both trip systems, the appropriate actions

'. listed below shall be taken.

.A. Initiate an orderly shutdown and have the reactor in Cold $hutdown condition in 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />.

B. Initiate an orderly load reduction and have reactor in Hot Standby within 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br />.

C .~ Close isolation valves in RCIC system.

D. Close isolation valves in HPCI subsystem.

3. Need not be operable when primary containment integrity is not required.
4. The isolation trip signal is bypassed when the mode switch is in Refuel or Startup/

Hot Shutdown.

l 5. The instrumentation also isolates the control romn ventilation system.

6. This signal also automatt ally closes the pechanical vacuum pump discharge line iso-lation valves.
7. Includes a time delay of 31 t i 9 seconds.
  • Top of active fuel is defined as 360* above vessel zero for all water levels used in the LOCA analysis (see Bases 3.2).

I 07408/0338Z 3.2/4.2-11 knenenent No.

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AlkNCilMEHI_2

SUMMARY

Of_ CHANGES The following changes have been identified for Quad Cities Station

, Units 1 and 2 Technical Specification:

1. Page 3.2/4.2-8 (DPR-29)

Page 3.2/4.2-6, 6a* (DPR-30)

(a) Remove "200*F" and insert "170*F"

  • Page 3.2/4.2-6a is a new page
2. Page 3.2/4.2-15 (DPR-29)

Page 3.2/4.2-11 (DPR-30)

(a) RCIC turbine area high temperature Remove "16" and insert "4" Remove "200*F" and insert "170*F" (b) HPCI area high temperature Remove "16" and insert "4" Remove "200*F" and insert "170*F" i

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-DESCRIPTIO'N OF THE PROPOSED AMENDMENT t-Current Technical Specification. Table 3.2-1, " Instrumentation That-

Initiates Primary. Containment Isolation" Functions", requires the minimum number of operable or trippef instrument channels to be sixteen (16) for the Reactor' Core Isolation Cooling (RCIC) or high Pressure Coolant Injection (HPCI) area high temperature isolation function. The trip level setting for these primary containment isolations is less than or equal to 200*F.

-The proposed Technical Specification requires that all temperature switches for the RCIC and HPCI isolation function' remain operable or in the tripped condition; however, due to the prgposed modification, the number of temperature switches 1s reduced to four (4). In addition, the temperature setpoint.for the isolation has been decreased to less than or equal to 170*F.

Commonwealth Edison proposes to amend the Technical Specification to support the upcoming modification of the HPCI and RCIC temperature monitoring system. The HPCI-and RCIC systems have two (2) isolation actuation setpoints to sense a steamline break. The isolation is actuated on a high flow or high area temperature. The high flow isolation was designed to assure system isolation in the event of a large steamline break. ' The high area temperature isolation is designed to assure isolation occurs for smaller steamline breaks. The modification to the temperature monitoring system was required due-to spurious.tsolation actuation occurring from minor steam leaks at the

' inboard and outboard gland seals on both the HPCI and RCIC systems.

The current temperature monitoring system on the liPCI and RCIC systems consist of a sixteen (16) temperature switches. The HPCI and RCIC temperature switches are configured in four groups of fo,r temperature switches. The location of the temperature switch groups for the PPCI system are above the HPCI steam inlet line, above the turbine rupture disk, and one group at each end of the turbine near the bearings. The RCIC temperature switcher, are located at the rupture disk, near the steam supply to the turbine and at both ends of the turbine at the shaft. A trip of two switches (one in each channel) at any one location will isolate the system. In the past, this location placement has resulted in spurious system isolation due to minor steam leaks at the turbine gland seals. These system leaks are negligible when compared to the system leaks anticipated for actual steamline breaks.

The current system configuration provides excessive sensitivity to local room hot spots which is not necessarily indicative of a steamline break.

The modified temperature monitoring system will consist of a total of four switches with two switches iristalled at the steam inlet piping and two 1 switches installed at the turbine exhaust rupture diaphragm for each system. '

The location of the switches are intended to maximize the system reliability and reduce the probability of spurious isolations. The calculations performed 0223T:5 l

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h y,,

A o L to justify the-reduction in the number of temperature switches are based on

l. bult room temperature;:therefore, switches will be located centrally in the.

E room,,able to sense' temperatures related to steamline breaks. The modified system is..therefore, capable of performing'its intended safety function. The

four switches will retain the one-out-of-two taken twice trip logic _ logic and will maintain divisional power supplies. In addition, the requirement that all instruments be operable or in the tripped conditions have been retained.

The two locations will minimize the potential for spurious isolations dus to

-_ minor steam leakage at the turbine gland seals yet adequately sense changes in bulk room temperature associated with an actual steamline break. The modification should increase the reliability of the HPCI and RCIC systems by elimirtting spurious isolations due to minor steam leaks.

p The trip. level setting will-be lowered to ensure adequ' ate system response. time and to maintain radiation release.within 10 CFR 100 limits. The new trip level setting of the area temperature monitoring system will be less than or equal to 170*F. This setting was verified to be conservative by calculations performed by Impell. The Impell calculations are based on an

analysis by Generic Electric which correlates the size of the steam leak to tk change in room temperature. The Iupell Calculation and General Electric Ahalysis are included as Attachments 5 and 6. The calculations conclude that a trip-level setting of less than or equal to 170*F will ensure an adequate system response time'while maintaining a low incidence of spurious isolation actuation.

Installation of this modification on Unit 1 HPCI and RCIC is currently planned during.the Unit 1 Refuel Outage beginning in September 1989 and ending in December 1989. A revision to Unit 1 Technical Specifications (DPR-29) reflecting installation of this modification on both Unit 1 HPCI and RCIC is included in this submittal. This revision should be implemented at the time of the installation of this modification during the Unit 1 Refuel Outage.

Installation of this modification on Unit 2 HPCI is currently planned for a short outage of sufficient duration prior to the next Unit 2 Refuel Outage. If no short outage is available, installation of this modification on Unit 2 HPCI will be performed in conjunction with the installation of this modification cn Unit 2 RCIC during the Unit 2 Refuel Outage currently scheduled for February 1990. Two revisions to Unit 2 Technical Specifications (DPR-30) are included in this submittal. The first revision to DPR-30 reflects installation of this modification on Unit 2 HPCI and not Unit 2 RCIC. This revision should be implemented should the modification to Unit 2 HPCI be installed during a.short outage prior to the next Unit 2 refuel outage. The second revision to DPR-30 reflects installation of this modification on both Unit 2 HPCI and RCIC. This revision to DPR-30 should be implemented at the time of installation of this modification on Unit 2 RCIC during the Unit 2 Refuel Outage. Should the modification on Unit 2 HPCI be instd led in conjunction with the modification on Unit 2 RCIC during the next Unit 2 Refuel Outage, the first revision to DPR-30 will be omitted and the second revision implemented.

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AIJACLEENT 4 N0_SIQlIFICANT H'AZARDS CONSID.ERATION As discussed in the Description of the Proposed Amendment Request,

,.the proposed change involves reducing the number of temperature switches for l the High Pressure Injection Coolant (HPCI) and Reactor Core Isolation Cooling (RCIC) system isolations. In addition to the reduction'in switches, the setpoint at. which an isolation occurs will also be decreased.'. These changes have been reviewed by Commonwealth Edison and we believe that they do not  ;

present a Significant Hazards Consideration. The basis for that determination l 1s documented below:

i l

l fBSIS FOR NO SIGNIFICANT HAZARDS CONSIDERATION I Commonwealth Edison has evaluated this proposed amendment and determined that the change involves a no significant hazards consideration.

In'accordance with the criteria of 10 CFR 50.92(c):  :

1. The proposed change does not_ involve a significant increase in the {

probability or consequences of an accident previously evaluated. l The.HPCI and RCIC high temperature instruments are provided to detect a '

l smaller break in the piping than that which would result in a 3007. flow in the piping. Tripping of the high area temperature instrumentation results in the actuation of the RCIC'or HPCI isolation valves. The trip logic for j this isolation actuation is a one-out-of-two twice instrument trip and, as i such, all sensors are required to be operable or in a tripped function to meet-single-failure criteria. The trip settings.of the high area i temperature and high flow as well as valve closure times assure that core i uncovery is prevented and fission product release'is maintained within i limits. i l

The proposed modification to the HPCI and RCIC high temperature switches

l. does not significantly increase the probability or consequence of an accident previously evaluated since the isolation function of the HPCI or RCIC. temperature monitoring system 1s not affected. The reduction in the number of temperature switches is accompanied by a decrease in the trip level setting to assure acceptabir rr oonse time and thereby minimizing the radiation releases to the room. Tnt proposed change does not affect the one-out-of-two twice trip logic or tN. requirement that all sensors are operable or in the tripped position. Calculations have been performed to-support the reduction in the number of switches and the reduction in the' trip setting.

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'2.. The proposed change will not create the possibility of a new or different kind of accident from any. accident previously evaluated.

The proposed Technical Specification-is submitted to support a proposed K modification to the HPCI and RCIC. temperature monitoring system which reduces the' number of temperature. switches. The system isolation logic design a'nd the need for all instruments to be operable or in the' tripped.

condition has not been changed. The trip level-setting is reduced (i.e.,

more conservative) to ensure adequate system response times and to maintain radiation levels within the limits of 10 CFR 100.

As such,.lsolation'of the HPCI and RCIC systems will occur when the bulk room temperature reaches the new trip setpoint (170*F) which would be indicative of a steamline break of the system. Calculations have been performed to demonstrate that the new temperature setpoint provides

.ad equate assurance of system actuation in the event of a steamline break.

The reduction'of the number of switches prevents spurious isolations due to small localized steam leaks and removes the system sensitivity to area

" hot spots", primarily at the. turbine gland seals. The system reliability is thereby increased by decreasing the number of unwanted system

. challenges.

Since the isolation' function remains and the setpoint has been revised to accommodate for iha system configuration, no new or different kind of accident from any at.rtdent previously evaluated has been created.

3. . The proposed';hange does not involve a significant reduction in the margin of safety.

The purpose of the Rt,iC and HPC7 system isolation is to assure system isolation in the event of a steamline break to prevent inventory loss and maintain radiation doset to less than 10 CFR 100 limits. The modified system will maintain sepa,=t'.on criteria for electric power supplies. The one-out-of-two taken twice trip logic will be retained so that the isolation capability is maintained in the event of single switch failure.

A large steam leak resulting from the rupture of the RCIC or HPCI steam supply line'would cause the high' flow-instrumentation to provide a trip of the isolation logic. 'For smaller leaks, the bulk room temperature of the HPCI and RCIC rooms would increase thus resulting in the actuation of the temperature isolation. The reduction in the number of temperature switches.is accompanied by a reduction, in the conservative direction, of temperature isolation setpoint which will assure adequate system response.

The current high flow isolation, accompanied by the modified temperature isolation, assures that only a minimal inventory loss occurs, thus preventing core uncovery and ensuring that 10 CFR 100 requirements are not exceeded; therefore, a significant reduction in the margin of safety does not occur.

0223T:8

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