ML20199K518

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Application for Amend to License NPF-11,adding Automatic Primary Containment Isolation on Ambient & Differential Temp High for RWCU Pump,Pump Valve,Holdup Pipe & F/D Valve Rooms. W/Environ Assessment Statement & Calculations
ML20199K518
Person / Time
Site: LaSalle  Constellation icon.png
Issue date: 11/24/1997
From: Subalusky W
COMMONWEALTH EDISON CO.
To:
NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
Shared Package
ML20199K523 List:
References
NUDOCS 9712010144
Download: ML20199K518 (25)
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Text

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November 24,1997 United States Nuclear Regulatory Commission Attention: Document Control Desk Washington, D.C. 20555

Subject:

LaSalle County Station Unit 1 Request for Technical Specification Amendment Facility Operating License NPF-11 Leak and Break Detectiois Isolation Instrumentation.

NRC Docket Nos. 50-373 and 50-374 Pursuant to 10 CFR 50.90, Commonwealth Edison Company (Comed) proposes to revise Appendix A, Tochnical Specifications of Facility Operating License NPF-11, LaSalle County Station Unit 1. The proposed changes include changes to the Technical Specifications (TS) which:

. add automatic primary containment isolation on Ambient and Dif;erential Temperature (AT) High for the Reactor Water Cleanup System (RWCU)

Pump, Pump Valve, Holdup Pipe, and Filter /Demineralizer (F/D) Valve Rooms; e add automatic primary containment isolation on RWCU Pump Suction Flow - High;

  • revice the ambient and differential temperature isolation setpoints in the RWCU Heat Exchanger Rooms; e eliminate the Residual Heat Removal (RHR) System steam condensing mode isolation actuation instrumentation; and
  • eliminate the ambient and differential temperature alarm and isolation functions for the RHR System shutdown cooling mode.

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Currently the RWCU pump rooms have no temperature monitoring because they contain " cold" piping. A design modification that restores " hot" suction to the RWCU pumps determined that the RWCU pump rooms and associated new pump valve room require leak detection isolation instrumentation. The setpoints for the heat exchanger rooms are being changed as a result of new design basis calculations. The new ambient and differential temperature leak detection for the RWCU holdup pipe area and the F/D valve room and the RWCU pump suction high flow switch are being added to minimize the impact of line breaks in these areas. The steam condensing mode of the RHR system is no longer utilized. Area temperature monitoring of the RHR shutdown cooling mode lines is being deleted because the system mode has been recognized as a moderate energy line and because area temperature monitoring is not offective since the energy in these lines is not sufficient to increase the area temperatures to detectable levels. These lines are in service in Cold Shutdown or at low reactor pressures in Hot Shutdown.

Th'*. proposed amendment request is subdivided as follows:

1. Attachment A gives a description and safety analysis of the proposed changes in this amendment.
2. Attachment B includes the marked-up License / Technical Specifications pages for LaSalle Unit 1 with the requested changes indicated.
3. Attachment C describes Comed's evaltation performed in accordance with 10 CFR 50.92 (c), which confirms that no significant haza-d consideration is involved.
4. Attachment D provides an Environmental Assessment Statement Applicability Review per 10 CFR 51.21.
5. Attachment E is the Summary of Sargent and Lundy (S&L)

Calculations For Revised Heat Loads For the RWCU Areas Affected By the Modification That Changes the RWCU System From a Cold Suction To a Hot Suction.

6. Attachment F is Calculation No. L-001281, Rev.1, Nov. 07,1997, RWCU Areas Temperatts Response Due To High Energy RWCU Fluid Leakage.
7. Attachment G is Calculation No. L-001324, Rev.1, Nov.13,1997, Area Ambient and Differential Temperature Design Basis Calculations For Reactor Coolant Leak Detection.
8. Attachment H is Calculation No. 3C7-1184-001, Rev.1, Dated May 7,1986, ECCS Room Leak Detection Setpoints.
9. Attachment I is Calculation No. L-001420, Rev.1, Dated November 19,1997, Unit 1 RWCU Room Setpoint Margin Analysis and Loop Accuracy.
10. Attachment J is Calculation No. L-001443, ,'4ev. O, Dated November 21,1997, Reactor Water Cleanup High Flow Isolation Error Analysis.

This proposed amendment has been reviewed and approved by Comed Onsite and Offsite Review in accordance with Commonwealth Edison procedures.

Comed requests approval of this license amendment request prior to startup of LaSalle, Unit 1, from its current forced outage, L1F35, currently scheduled for April 2,1998. The amendment should be made effective upon issuance for Unit 1. Comed willimplement the amendment prior to startup of LaSalle, Unit 1, from the current outage.

Comed is notifying the State of Illinois of this application for amendment by transmitting a copy of this letter and its attachments to the designated state official.

If there are any questions or comments conceming this letter, please refer them to Perry Barnes, Regulatory Assurance Supervisor, at (815) 357-6761, extension 2383.

Respectfully, h

W. T. Subalusky Site Vice President LaSalle County Station Enclosure cc: A. B. Beach, NRC Region lil Administrator M. P. Huber, NRC Senior Resident inspector - LaSalle D. M. Skay, Project Manager - NRR - LaSalle F. Niziolek, Office of Nuclear Facility Safety - IDNS

l STATE OF ILLINOIS )

COUNTY OF LASALLE )

Docket Nos. 50 373 IN THE MATTER OF )

COMMONWEALTH EDISON COMPANY ) l LASALLE COUNTY STATION UNIT 1 )

l AFFIDAVIT l affirm that the content of this transmittalis true and correct to the best of my knowledge, information and belief, t

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d William T. Subalu o w

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Site Vice Presid t j LaSalle County stion /

Subscribed and swom to before me, a Notary Public in and for the State and County above named, this 48 day of A la wa,t Aw , 1997 . My Commission expires on to- i , de c o .

0FFICIAL SEAL NOTARY PUBLIC, STA ILLIN0!S Nbtary Public uv couvissioN UPtRES10+2000 l

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ATTACHMENT A DESCRIPTION OF SAFETY ANALYSIS OF THE PROPOSED CHANGES

SUMMARY

OF THE PROPOSED CHANGES Commonwealth Edison Company (Comed) proposes to revise Appendix A, Technical Specifications of Facility Operatina License NPF-11, LaSalle County Station Unit 1. The proposed changes include changes to the Technical Specifications (TS) which:

Pump, Pump Valve, Holdup Pipe, and Filter /Demineralizer (FID) Valve Rooms;

  • add automatic primary containment isolation on RWCU Pump Suction Flow - High; a revise the ambient and differential temperature isolation setpoints in the RWCU Heat Exchanger Rooms;
.
  • elir.1lnate the ambient and differential temperature alarm and isolation furections for the RHR System shutdown cooling mode.

L Currently the RWCU pump rooms have no temperature monitoring because they contain " cold" piping. A design modification that restores " hot" suction to the RWCU pumps determined that the RWCU pump rooms and associated new pump valve room require leak detection isolation instrumentation. The setpoints for the heat exchanger rooms are being c5anged as a result of new design basis calculations. The new ambient and differential 4

temperature leak detection for the RWCU holdup pipe area and the FID valve room and the RWCU pump suction high flow switch are being added to minimize the impact of line breaks in these areas. The steam condensing n. ode of RHR system is no longer utilized. Area temperature monitoring of the RHR shutdown cooling mode lines is being deleted because the system mode has been recognized as a moderate energy line and because area temperature monitoring is not effective since the energy in these lines is not sufficient to increase the area temperatures to detectable levels. These lines are in service in Cold Shutdown or at low reactor pressures in Hot Shutdown.

A-1 e

l ATTACHMENT A DESCRIPTION OF SAFETY ANALYSIS OF THE PROPOSED CHANGES DESCRIPTION OF THE CURRENT REQUIREMENTS _

Technical Specification Table L3.21 requires the following Automatic Primary Containment isolation instrument trip functions to be OPERABLE, with setpoints as listed in Table 3.3.2 2:

A.3 Reactor Water _ Cleanup System isolation

b. Heat Exchanger Area Temperature - High, with a setpoint of s 181*F and an allowable value of s 187'F. The Minimum Operable Channels Per Trip System is "1/ heat exchange",
c. Heat Exchanger Area Ventilation AT - High, with a setpoint of s 85'F with an allowable value of s 91*F. The Minimum Operable Channels Per Trip System is "1/ heat exchange".

I A.5 RHR System Steam Condensina Mode isolation

a. RHR Equipment Area A Temperature - High, with a setpoint of s 50'F and an allowable value of s 56'F. The Minimum Operable Channels Per Trip System is "1IRHR area".
b. RHR Area Temperature - High, with a setpoint of s 200'F and an allowable value of s 206*F. Tables 3.3.2 2, 3.3.2 3, and 4.3.2.1-1 state this Trip Function as "RHR Area Cooler Temperature - High".

The Minimum Operable Channels Per Trip System is "1/RHR area",

c. RHR Heat Exchanger Steam Supply Flow - High. with a setpoint of s 123" H2 O and an allowable value of s 128" H2 0. The Minimum Operable Channels Per Trip System is "1".

A.6 BHR System Shutdown Coolina Mode isolation

d. RHR Area Temperature - High, with a setpoint of s 200'F and an allowable value of s; 206*F. Tables 3.3.2-2 and 3.3.2-3 state this Trip Function as "RHR Area Cooler Temperature - High". The Minimum Operable Channels Per Trip System is "11RHR area".

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ATTACHMENT A DESCRIPTION OF SAFETY ANALYSIS OF THE PROPOSED CHANGES

e. RHR Equipment Area AT - High, with a setpoint of s 50'F and an allowable value of s 56*F The Minimum Operable Channels Der Trip System is "1/RHR area".

The Applicable Operational Conditions for the instrumentation channels, are listad in Table 3.3.21 as Conditions 1,2, and 3.

The TS Suweillance Requirements (SRs) for each of the above trip functions are as follows:

  • Channel Checks are "NA" (Not Applicable),
  • Channel Functional Tests are "Q" (quarterly), and
  • Channel Calibrations are "Q" (quarterly).

These technical specific &n requiremsnts pertain to the area temperature and differential temperature leak detection monitors which are located in equipment areas of systems outside primary containment that carry hot reactor coolant.

When these monitors sense a leakage of hot reactor coolant in excess of the established leakage rate limit, by sensing an increase in the equipment area i

temperature or area ventilation differential temperature, an isolation of the  ;

system containment isolation valves is actuated. The established leakage rate '

limit for isolation is a temperature or differential temperature corresponding to a 25 gpm leak, in accordance with the GE design specification recommendation ,

for the leak detection system. I For each of the above trip functions, the isolation logic consists of two trip systems, one for the inboard containment isolation logic and one for the outboard containment isolation logic. Each of these trip systems contains one channel. A trip of a single channel causes the associated inboard or outboard valve group to isolats as designated in TS Table 3.3.2-1. RWCU containment isolation valve group is 5 (five).

The design bases for the temperature and diffarential temperature leak detection primary containment isolation control instrumentation is set forth in UFSAR Section 7.3.2 and includes appropriate redundancy, electrical and physical ,

separation, and seismic and environmental qualification. '

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ATTACHMENT A I

DESCRIPTION OF SAFETY ANALYSIS OF THE PROPOSED CHANGES SA3fS FOR THE CURRENT REQUIREMENTS The basis for Technical Specification 314.3.2 states the following concerning isolation Actuation Instrumentation trip settings: )

"Some of the trip settings may have tolerances explicitly stated where '

both the high and low values are critical and may have a substantial effect j on safety. The setpoints of other instrumentation, where only the high or low end of the setting have a direct bearing on safety, are established at a level away from the normal operating range to prevent inadvertent .!

actuation of the systems involved."

Safety design bases (a), (b), and (d) for the primary containment isolation control system are stated M UFSAR Section 7.3.2.1 as follows:

i "a. To limit the release of radioactive materials to the environs, the primary containment and reactor vessel isolation control system shall, with precision and reliability, initiate timely isolation of penetrations through the primary containment whenever the values of monitored variables exceed preselected operational limits."

"b. To provide assurance that important variables are monitored with a precision sufficient to fulfill safety design basis (a), the primary containment and reactor vessel isolation control system shall respond correctly to the sensed variables over the expected design range of magnitudes and rates of change."

"d. To provide assurance that conditions indicative of a failure of the reactor coolant pressure boundary are detected to fulfill safety design basis (a), primary containment and reactor vessel isolation cont &ol system inputs shall be derived from variables that are true, direct measures of operational conditions."

The safety design basis for leakage detection is given in the following excerpt from UFSAR Section 5.2.5.5.4:

"For process lines that are normally open, there are at least two different methods of detecting abnormal leakage from each system within the nuclear system process barrier located in the drywell, reactor building, A-4

' ATTACHMENT A DESCRIPTION OF SAFETY ANALYSIS OF THE PROPOSED CHANGES and auxiliary building, as shown in Table 5.2-8. The instrumentation is designed so it can be set to provide alarms at established leakage rate limits and isolate the affected system, if necessary. Tine alarm points are determined analytically or based on measurements of appropriate parameters made during startup and preoperational tests."

The UFSAR states the following in Section 5.4.7.2.2.3 concerning deletion of the steam condensing mode of RHR from use:

"The procedures governing Steam Condensing Mode Operation have been deleted and a review of other procedures that operate the below listed valves, concluded that these valves are not required to operate in plant emergency proceaures."

NEED FOR REVISION OF THE REQUIREMEN TS

1. The original RWCU system design included " hot" pump suction from the Reactor Recirculation System. This " hot suction" presented problems with the pump seal design and therefore the RWCU system was modified per General Electric AlD 25-79 to provide the pumps with " cold suction" t

from downstream of the non-regenerative heat exchangers. As a result of this modification the temperature monitoring function of the leak l detection system in the pump rooms became meaningless and so it was eliminated by license amendments NPF-11, No. 20 and NPF-18, No. 7 (TAC Nos. 55773 and 55774).

l Although the " cold" suction eliminated several seal issues, it introduced other issues such as fluid flashing / voiding at the regenerative heat exchanger inlet and seveia pump vibrations. The current design modification returns the RWCU system to the original configuration with

" hot suction" by utilizing improved design pumps that can withstand the l " hot suction" and this in turn creates the need to re-establish the l temperature monitoring function of the Leak Detection system in the pump and pump valve rooms. The previous design utilized three 50%

capacity RWCU pumps in separate rooms. The current configuration has i two 100% capacity pumps in separate rooms, separated by an intervening valve room, which is designated as the pump valve room.

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l ATTACHMENT A DESCRIPTION OF SAFETY ANALYSIS OF THE PROPOSED CHANGES

2. As a result of a High Energy Line Break (HELB) analysis re evaluation conducted recently, it was detonnined that some portions of the " hot" RWCU piping would not isolate in time, after the occurrence of a break, prior to causing Environmental Qualificc'Jon (EQ) temperatures in adjacent areas to be exceeded. This condition was reported as a condition that was potentially outside tha design basic of the plant in LaSalk License Event Report (LER)97-033. l The existing leak detection isolation niethod for these areas is the RWCU  ;

Differential Flow - High, with a setpoint of s 70 gpm and an allowable l valus of s 87.5 gpm. This method has a 45 second time delay for operational considerations. In order to provide a more rapid response (without time delay) to these areas, should a break occur, additional

datection will be provided consisting of temperature leak detection in the RWCU Holdup Pipe and FID Valve Rooms and RWCU Pump Suction High Flow break detection.
3. Leak detection monitoring for the RWCU heat excnanger rooms is currently based on both high temperature and high AT. The current setpoints had been based on calculations of the expected bounding summer temperature or AT conditions that would result due to a leak of the highest RWCU process temperature fluid.

The RWCU heat exchanger room alarms and isolation setpoints were established, based on expected summer conditions. The following table compares the current alarm and isolation setpoints to the leakage values obtained from a special calculation to evaluate the safety analysis for LaSalle LER 97-031, with respect to various ambient conditions, including the zero leakage condition for comparison:

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ATTACHMENT A .

DESCRIPTION OF SAFETY ANALYSIS OF THE PROPOSED CHANGES Summer Nominal Winter Current Current T AT Setpomt Setpoint

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Ventilation air 103 94 60 '

inlet T 0 gpm loak 117 104 74 exhaust T 5 gpm leak 167 124 96 130 34 exhaust T alarm 25 gpm leak 198 180 141 181 -

85 exhaust T isolation f

Representative winter values (specially calculated for this purpose) have been included in the table for comparison. Tiie 0 gpm leak reflecte the equipment produced heat load.

As the table shows, the high temperature setpoint will isolate on less than 25 gpm leakage during summer conditions when the temperature reaches 181 'F but it will require a leak greater than 25 gpm to actuate isolation during the nominal and winter conditions. This cors,ifon was reported as operation outside the design basis and TS in LER 97-031.

The current design modification returns the RWCU system to the original i

configuration with hot suction" by utilizing improved design pumps, different pipe sizes, slightly modified piping configuration, etc., and requires revised design documents. New leak rate and setpoint calculations for the pump and heat exchanger rooms, have been performed. The results of these calculations have indicated the need for changing the heat exchanger room setpoints.

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ATTACHMENT A .

DESCRIPTION OF SAFETY ANALYSIS OF THE PROPOSED CHANGES

4. The steam condensing mode of the RHR while in operating conditions 1, 2, or 3, was deletsd as reported in the Comed October 20,1992 letter (J.

Shields to T.E. Murley). The UFSAR was updated accordingly at that time, however no Technical Specification change was submitted. The need to have consistent documentation results In this change request to delete the associated isolation actuatic,5 em functions, A.5, from TS Table 3.3.21, 3.3.2 2, 3.3.2-3, and 4.3.2.1-1.

5. Area temperature monitoring of the RHR shutdown cooling mode lines is intended to provide assurance that important variables are monitored with a sufficient precision so that the isolation control system shall respond correctly to the sensed variables. However, calculations for temperature response show that, the RHR shutdown cooling area temperature and AT sensors are not affected significantly as a result of a leak because the shutdown cooling lines are moderate energy lines. Therefore, these variables are not the important variables that can be monitored with 4 precision to assure correct response of the isolation control system.

L The high temperature and AT isolation actuation Instrumentation trip functions A.6.d and A.6.e, respectively, have setpoints and allowable values that are non-conservative with respect to design calculations. This was also reported in LER 07-031. Therefore, these trip functions are proposed to be deleted from TS.

DESCRIPTION OF THE PROPOSED CHANGES -

l Only the setpoint sad allowable values for RWCU items A.3.b and A.3.c change accordingly in Table 3.3.2-2, while the new trip functions A.3.f through A.3.1 are being added and require changes to Tables 3.3.21, 3.3.2-2, 3.3.2 3, and 4.3.2.1-1.

i The applicable operational conditions for the instrumentation channels in Table 3.3.2-1 are unchanged for the RWCU heat exchanger rooms high temperature and AT trip functions and will be the same Operational Conditions for the added trip functions. -The Minimum. Operable Channels per Trip System are 1 or 1/ area or room as applicable, like the existing similar trip functions. Action 22 also j applies to the new RWCU trip functions, because they involve the same valve group.

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ATTACHMENT A DESCRIPTION OF SAFETY ANALYSIS OF THE PROPOSED CHANGES 1

The proposed change to the Technical Specifications changes the setpoints for ,

trip functions A.3.b. and A.3.c. In TS Table 3.3.2-2 and tv'ds new trip functions  !

A.3.f through A.3.1 to TS Tables associated with TS 3.t . l l

The proposed setpoints are as follows for the following revised or added isolation actuation instrumentation functional units for changes to TS Table 3.3.2 2:

A.3 Reactor Watcr Cleanuo System Isolation

b. Heat Exchanger Area Temperature - High, with a setpoint of s 149'F and an allowable value of s 156.8* F.
c. Heat Exchanger Area Ventilation AT - High, with a setpoint of s 33*F and an allowable value of s 40.3* F.
f. Pump and Pump Valve Area Temperature - High, with a setpoint of s 201' F and an allowable value of s 209' F.
g. Pump and Pump Valve Area Ventilation AT - High, with a setpoint of s 86* F and an allowable value of s 92.5* F.
h. Holdup Pipe Area Temperature - High, with a setpoint of s 201' F and an allowable value of s 209' F.
i. Holdup Pipe Area Ventilation AT - High, with a setpoint of s 86* F and an allowable value of s 92.5' F.

J. Filter /Demineralizer Valve Room Area Temperature - High, with a setpoint of s 201' F and an allowable value of s 209' F.

k. Filter /Demineralizer Valve Room Area Ventilation AT - High, with a setpoint of s 86* F and an allowable value of s 92.5' F.
l. Pump Suction Flow - High, with a setpoint of s 500 gpm and an allowable value of s 550 gpm.

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l ATTACHMENT A -

DESCRIPTION OF SAFETY ANALYSIS OF THE PROPOSED CHANGES RWCU trip functions A.3.f through A.3.1 are being added to TS Table 3.3.2-3, and likewise do not require response time testing, because the valve group depends on_ emergency diesel generator start time of 13 seconds for valve movement to begin.

The proposed TS SRs for the new RWCU temperature and AT trip functions are as follows:

  • Channel Checks are "NA" (Not Applicable),
  • Channel Functional Tests are "Q" (quarterly), and
  • Channel Calibrations are "Q" (quarterly).

The proposed TS SRs for the RWCU pump suction flow - high trip function is the same as above, except the instrumentation hops being installed are analog channels which will allow a Channel Check. Therefore this trip function is proposea to have a "S" (shiftly) Channel Check.

The elimination of the RHR steam condensing mode trip functions (A.5) and the deletion of the RHR shutdown cooling mode temperature monitoring trip functions (A.6.d and A.6.e) will require deleting these trip functions from TS Tables 3.3.2 1, 3.3.2-2, 3.3.2-3, and 4.3.2.1 1.

All of the above changes and the deletions of trip functions A.5, A.6.d. and A.6.e are indicated on the marked-up pertinent Technical Specification pages (Attachment B).

Leak detection equipment being installed as a result of this change,-will have similar functional performance and surveillance requirements as the currently installed equipment and will meet the existing design bases requirements, in addition, the isolation logic, with 1 channel per trip system for each of the above trip functions is the same as that described in the current requirements section.

The RWCU pump suction flow - high trip function has the same logic and is consistent with RHR and RCIC high flow isolation actuation instrumentation trip functions.

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ATTACHMENT A DESCRIPTION OF SAFETY ANALYSIS OF THE PROPOSED CHANGES

BASES FOR THE PROPOSED CHANGES -

The criteria that have been applied to provide an upper and lower limit for isolation after detection of leakage are:

E

1. The isolation setpoints must be high enough to provide operational margin for weather changes, loss of ventilation, loss of normal heating of supply air, and other ventilation changes.
2. The isolation setpoints must be low enough so that they provide their function before th2 detected leakage exceeds the established leakage limit (25 gpm equival9nt mass at staidard conditions).

The approach used to determine a basis for the changes to the leak and break detection system isolation requirements is outlined below:

l

1. Other stations contacted do not utilize both ambient and AT for isolation uniformly. Nine Mile Point and Clinton isolate on high temperature only; WNP-2 and Susquehanna isolate on both high ambient and AT detection, however Susquehanna indicated that as a result of the improved i

Technical Specifications effort, they are eliminating the AT isolation function. Dresden and Quad Cities depend on operator action for isolation of the RWCU system, and Brunswick has automatic isolation on

system differential process flow only.

Other plants utilize water served fan coolers or have common areas for the pumps and heat exchangers. LaSalle's RWCU area rooms are l ventilated with 100% outside air which is tempered by the supply heat!ng

, colh, and staged through the general areas of the reactor building, prior to entering these rooms. This ventilation is the only cooling media for the RWCU areas.

. 2. A re evaluation of the HELB analysis for lines located in the Reactor Building was performed. This evaluation indicated areas whcto break

Isolation would not occur within the times utilized to determine the bounding area temperatures for Equipment Qualification (EQ). These areas are the RWCU high energy lines outside the equipment rooms where isolation is currently actuated by a high delta flow signal. This i

signal has a 45-second actuation delay for operational considerations 1

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l ATTACHMENT A DESCRIPTION OF SAFETY ANALYSIS OF THE PROPOSED CHANGES 1

(density changes occur in the system during startup and shutdown, and flow si' aos when the FID's are taken in and out of service). During this time t.. ,ay, additional mass energy is released, causing the temperature in ,

adjacent areas to possibly exceed the EQ temperature limits. To prevent this, RWCU pump suction flow detection with setpoints chosen high enough to avoid spurious isolations during pump and F/D swapping, but low enough so that breaks will be isolated prior to allowing the EQ

. temperature limits to be exceeded, is being provided.

3. Heat load and supply air flowrate calculations were performed to provide input to the leak detection design basis calculation (AM.chment F) and to reflect the new " hot" suction configuration of the RWCU system. A calculation summary is included in Attachment E.

i 4. Leakage rate calculations ( Attachment F and G) were pe formed for the areas without room coolers that utilize ambient and differential temperature leak detection isolation. These calculations used steady state conditions in accordance with the G " design specification.

l For the isolation actuation point based on the established leak rate limit cases of 25 gpm, bounding initial ventilation values were utilized and analytical limits were chosen so that the established leak rate limit was not exceeded except for the heat exchanger room. in this room, the analytical limits are now calculated based on the regenerative heat exchanger feedwater return temperatures (437' F) instead of the reactor coolant inlet to the regenerative heat exchanga temperature (533' F) .

This results in the established leak rate limit being exceeded for the extreme winter condition based on smbient temperature isolation (i.e., a leakage rate of 36.4 gpm will be necessary to actuate isolation with an inlet ventilation temperature of 65' F). It thould be noted that the differential temperature iaolation actuation is conservative under these same conditione, actuating at a leakags rate of 17 gpm. Additionally,

" hot" leakage (i.e., prior to the regenerative heat exchanger, 533* F) will conservatively actuate isolation under all ambient conditions at a leak rate less than the established limit. An ambient temperature setpoint that would actuate isolation for feedwater return temperatures (437' F) under all ambient conditions would increase the potential for spurious actuations.

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il ATTACHMENT A  :

DESCRIPTION OF SAFETY ANALYSIS OF THE PROPOSED CHANGES' For the alarm actur. tion point based or; the established leak rate limit cases of 5 gpm, design ventilation conditions were utilized and analytical limits based on summer conditions were typically chosen to ensure that

- adequate margin is provided during these con 6;3ons so that no spurious alarms are received. This, however, le.Js to a higher leakage rate being alarmed during the winter design cLnditions. In all cases, these alarm values are below the isolation actuation values, with the mat:imum value being 23.6 gpm. Therefore, there is still margin between the detection of a small leak with itc consequent alarm and the larger leak which results in automatic isolation of the system.

5. . Leak detection analytical setpoints for the RWCU areas anablent and differential temperature were calculated. See Attachment F for a copy of calculation L-001281.
6. Instrument Setpoint calculations were performed to determine that sufficient available margin exists as defined below, for the instrument loops that initiate a Group 5 isolation upon detection of high temperature, differential temperature, and suction flow,
a. The TS allowable and the nominal technical specification setpoint.
b. The analytical limit and the nominal TS setpoint.

The calculations are valid under normal and accident environmental conditions, and allow for all normal and accident errors. Thus technical specification compliance is ensured for the instrument channels. See Attachment I for a copy of calculation L-001420,

7. An evaluation of the remaining temperature isolation setpoints in Technical Specifications Table 3.3.2-2 was performed to assess their adequacy. This evaluation indicated that clarification of the temperature leak detection basis was needed but that the setpoints are adequate and therefore no change is necessary. The calculations are included as Attachments G and H.

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ATTACHMENT A DESCRIPTION OF SAFETY ANALYSIS OF THE PROPOSED CHANGES The following provides a summary of the results of the analyscs performed for the changes to the detection isolation Technical Specifications:

1. The process flow analytical value for the high suction flow instrumentation is conservatively established at 600 gpm. This flow rate was selected to be high enough to avoid spurious isolations during normal RWCU operations (maximum system flow is approximately 350 gpm) wh!le also being low enough to ensure that the break flow will be detected. The flow for the postulated bounding RWCU line break is over 6000 gpm. The setpoint calculation (Attachment J) provides one basis for the difference between the sotpoint and allowable value. The calculation determined the setpoint to be 500 gpm, with an allowable value of 550 gpm, for the suction line flow isolation, which ensures a high level of confidence that the analytical limit will not be exceeded under normal or accident operating conditions.
2. Based on the calculation of changes in AT (Mtachment F) in response to a leak, it was determined that with an established leak rate limit of 25 gpm or less, the AT analytical value will be 41.8' F for the heat exchanger roorr. 94* F for the pump and pump valve rooms,94* F for the holdup pipe room, and 94* F for the FID valve rooms. The setpoint calculations (Attachment I) provide the basis for the difference between the setpoints and allowable values. The calculations determined nominal setpoints for the differential temperature isolation setpoints, which ensure a high level of confidence that the analytical limit will not be exceeded under normal or accident operating conditions.
3. Based on the calculation of changes in temperaturo (T) (Attachment F) in response to a leak, it was determined that with an established leak rate limit of 25 gpm or less, the temperature analytical value will be 159.8* F for the heat exchanger room,212' F for the pump and pump valve rooms, 212' F for the holdup pipe room, and 212' F for the FID valve rooms. The setpoint calculations (Attachment 1) provide the basis for the dliference between the setpoints and allowable values. The calculations determined nominal soipoints for the temperature isolation setpoints which ensure a high level of confidence that the analytical limit will not be exceeded under normal _or accident operating conditions.

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l

ATTACHMENT A DESCRIPTION OF SAFETY ANALYSIS OF THE PROPOSED CHANGES

4. The results of the room temperature responses and setpoint calculations (Attachment 1) for the RWCU pump, heat exchanger, holdup pipe, and F/D

- valve rooms are shown in the following tables:

AT RWCU Leakage Analytical Allowable Isolation Alarm Rooms gpm Limit Value Setpoint Setpoint

(*F) (* F) (' F) (*F)

~

Pump Normal 0 18.0 - - -

Room Alarm 5 32.4 - - 28 Isolation 25 94.0 92.5 86 -

Pump Normal 0 17.6 - - -

Valve Alarm 5 41.0 - - 37 Room isolation 25 94.0 92.5 86 -

Hx Normal 0 17.6 - - -

Room Alarm 5 24.6 - - 20 Isolation 25 41.8 40.3 33 -

Holdup Normal 0 17.3 - - -

Pipe Alarm 5 40.8 - - 37 Area Isolation 25 94.0 92.5 86 -

~

FID Normal 0 19.6 - - -

Valve Alarm 5 44.5 - - 40 Room isolation 25 94.0 92.5 86 -

A 15

l ATTACHMENT A DESCRIPTION OF SAFETY ANALYSIS OF THE PROPOSED CHANGES Ambient T RWCU Leakage Analytical Allowable Isolation Alarm Rooms gpm Limit Value Setpoint Setpoint

( F) (*F) (* F) (*F)

Pump Normal 0 122.0 - - -

Room Alarm 5 136.4 - - 131 Isolation 25 212.0 209 201 -

Pump Normal 0 121.6 - - -

Valve Air.rm 5 145.0 - - 140 Room isolation 25 212.0 209 201 -

Hx Normal 0 121.6 -

l Room Alarm 5 128.6 - - 124 isolation 25 159.8 156.8 140 -

Holdup Normal 0 U1,3 - - -

Pipe Alarm 5 i44.8 - - 140 Area isolation 25 212.0 209 201 -

1 F/D Normal 0 523.6 - - -

Valve A! arm 5 148.5 - - 143 Room isolation 25 212.0 209 201 -

A-16 l

. - . -. . - - - . _ - .~.- - _ _ -. - .. - _ - - . - --.- -__.. -- - _ _ .-

ATTACHMENT A DESCRIPTION OF SAFETY ANALYSIS OF THE PROPOSED CHANGES The following is the primary basis for the r;oposed changes to the sicection isolation Technical Specifications: .

1. The proposed Technical Specification adds new trip functions A.3.f, A.3.g, A.3.h, A.3.1 A.3.J, and A.3.k, for Area Temperature - High and Area Ventilation AT - High in RWCU pump, pump valve, holdup pipe, and F/D valve rooms, and new trip function A.3.1 for the RWCU Pump Suction Flow-

- High, with associated requirements for Tables 3.3.2-1,3.3.22,3.3.23, and 4.3.2.1-1. The basis for the addition is the safety design basis for the primary containment isolation control system of UFSAR section 7.3.2.1, which has been quoted above in " Bases for the Current Requirements".

l

2. The proposed Technical Specification setpoint for Table 3.3.2-2, for the RWCU Pump Suction Flow - High, will be 500 gpm with an allowable value of 550 gpm based on the results of setpoint calculations (Attachment J) and the analytical values for the process flow rate resulting form a pipe break.

l

3. The proposed Technical Specification setpoints for Table 3.3.2-2, for the RWCU Pump, Pump Valve Area Temperature - High will be 201' F with allowable values of 209' F, and for the RWCU Pump and Valve Area Ventilation AT - High will be 86* F with an allowabie value of 92.5' F based on the results of setpoint calculations (Attachment I) and the analytical values from calculations (Attachment F) of the area temperature and differential temperature result!ng from an established leak rate limit of 25 gpm.
4. The proposed Technical Specification setpoints for Table 3.3.2-2, for the RWCU Holdup Pipe Area Temperature - High will be 201* F with n.n allowable value of 209' F, and for the RWCU Holdup Pipe Area Ventilation AT - High will be 86* F with an allowable value of 92.5' F based on the results of setpoint calculations (Attachment I) and the analytical values from calculations (Attachment F) of the area temperature and differential temperature resulting from an established leak rate limit of 25 gpm.
5. The proposed Technical Specification setpoints for Table 3.3.2-2, for the RWCU FID Valve Area-Temperature - High will be 201' F with an allowable value of 209' F, and for the RWCU FID Valve Area Ventilation AT - High will be 86* F with an allowable value of 92.5' F based on the results of A-17 t

~ --- m

ATTACHMENT A DESCRIPTION OF SAFETY ANALYSIS OF THE PitOPOSED CHANGES setpoint calculations (Attachment I) and the analytical values from calculations (Attachment F) of the area temperature r.nd differential temperature resulting from an established leak rate limit of 25 gpm.

6. The proposed Technical Specification setpoints for Table 3.3.2-2, for the Heat Exchanger Area Temperature - High will be 149' F with sn allowable value of 156.8* F, and for the Heat Exchanger Area Ventilation AT - High will be 33' F with an allowable value of 40.3' F based on the results of setpoint calculations (Attachment I) and the analytical values from calculations (Attachment F) of the area temperature and differential temperature resulting from ar, estabilshed leak rate limit of 25 gpm.
7. The proposad Technical Specliication setpoints are based on controlled room thermal response to a leak as predicted by thermal steady state calculations (Attachment F) from the extreme expected room ambient conditions The setpoints provide sufficient mr.rgin above operating temperature to preclude inadvertent isolations and detect leakage equivalent to 25 gpm water at these room conditions, which is consistent with tlee GE design specifications and the basis used at other BWR's.

The basis for the proposed de!stion of the trip function A.5 in the Technical Specification 3/4.3.2 for the RHR system steam condensing mode isolation is

! the non utilization of this mode of operation at LaSalle in the applicable Operational Cenditions.

The following provide the bases for the proposed deletion of the temperature initiated trip functions in the RHR system shutdown cooling mode isolation:

1. The safety design bases for the primary containment isolation control system in UFSAR Section 7.3.2.1(a), (b) and (d), quoted previously above in " Basis for Current Requirements", irdends the temperature monitoring of the RHR shutdown cooling mode areas. to provide assurance that important variables are monitored with a sufficient precision so that the

- ! solation control system shall respond correctly to the sensed variables.

Calculations (Attachment H) for temperature response show that, for a 25 gpm leak from the RHR shtddown cooling lines at their highest possible process temperature, the resultant analytical room temperature is less

' nan 130*F. Leaks at lower process temperatures result in lower room temperatures. The design temperature of the RHR rooms is 148'F.

A-18 o

ATTACHMENT A DESCRIPTION OF SAFETY ANALYSIS OF THE PROPOSED CHANGES-

, Summer room temperatures may reach 110 'F. The required isolation setpoint for a 25 gpm RHR shutdown cooling mode leak is sufficiently close to operating room conditions such that the possibility for spurious isolation actuations would be greatly increased. The relatively low heat input to the room from the leak and room cooler operation, when the.

equipment is operating, limits the effectiveness of the differential temperature monitors. Additionally, the RHR shutdown cooling process temperatures are not detectable (i.e., <212 'F) by area temperature leak detection for over 99% of shutdown cooling operating time. Therefore, temperature is not the appropriate parameter for leak detection, as it does not provide meaningful indication and will not provide setpoints that would be sufficiently above the normal range of ambient conditions to avoid spurious isolations.

2. There are two remaining different methods of detecting abnormal leakage and isolating the system in technical specification trip function A.6, namely A.6.a. Reactor Vessel Water Level - Low, Level 3 and A.6.c, RHR Pump Suction Flow - High, in addition, other means to detect leakage from the RHR system, such as sump monitoring and area radiation monitoring, are also available. Therefore the safety design basis for the leak detection system in UFSAR Section 5.2.5.5.4, which was quoted previously in " basis for the current requirements", is not compromised.

l In accordance with TS Administrative Requirement 6.2.F.1, LaSalle has a leakage reduction program to reduce leakage from those portions of systems outside primary containment that contain radioactive fluids.  ;

i RHR, including piping and components asscciated with the shutdown l coolinJ mode, is part of this program, which includes periodic visual l inspection for system for leakage. The sump monitoring, radiation monitoring and periodic inspections for system leakage makes the probat'llity of a leak of 5 gpm going undetected for more than a day very low.

l l

A-19

ATTACHEENT A DESCRIPTION OF SAFETY ANALYSIS OF THE PROPOSED CHANGES

- Also, due to the low reactor pressures (less than 135 psig) at which RHR shutdown cooling mode is able to operate, reactor coo! ant makeup and outflow is very low compared to normal plant operation. A change in flow i,

balance due to a leak is thus more readily detectable with reactor coolant water level changes and makeup flow rate, and thus precludes a significant leak going undetected before break detection instrumentation would cause automatic isolation.

The following provides clarification of the temperature leak detection basis for the T and AT isolation setpoints of Technical Specification Table 3.3.2-2 that do

-not require changes to the TS.

1. The RCIC Equipment Area monitors will only isolate at an established leakage rate limit of 15 gpm when the RCIC pump is not operating. This is considered the normal room environment, and I. therefore consistent with the GE design specification whl: h states that the setpoints should be calculated (Attachment H) by doing a heat balance for the normal room environment. The RCIC equipment area room cooler operates when the pump is running, and its operation controls the room temperature. This occurs during infreqcent testing periods, or during postulated accident conditions. During those times, other means of leak detection are available, such as. high steam flow or sump indications. Area temperature and differential temperature will be available for detection and isolation, but at a higher established leak rate limit (approximately 40-50 gpm).
2. Not all areas of systems containing reactor coolant outside primary containment are provided with temperature and differential temperature leak detection monitors. This is indicated in UFSAR Table 5.24. The systems must regularly carry hot coolant in order for the temperature based system to be effect!ve. The temperature monitors are provided in equipment area rooms, since open piping areas are typically expansive, rendering ambient temperature detection ineffective. The open piping areas also usually contain piping from many systems that would be subject to isolation from leakage from one system.
3. The leak detection methods whin actuate containment isolation are indicated in UFSAR Table 5.24. The established leakage rate limit for the different isolation methods are also different depending upon operational considerations. This is consistent with the leakage detection safety A-20

l ATTACHMENT A DESCRIPTION OF SAFETY ANALYSIS OF THE PROPOSED CHANGES design basis provided in UFSAR Section 5.2.5.5.4. Additionally, as Indicated in UFSAR Table 5.2 8, some areas have leak detection that may.

not result in automatic isolation. This is consistent with GDC 54, so long as there are redundant means of detection.

4. The area temperature and differential temperature detection and isolation sensors are affected by varying ambient temperature conditions. The established leak rate limit setpoints are calculated (Attachments F, G, and H) at design conditions. When actual conditions vary, the leakage rates correlating with the detector setpoints may also vary.

S_CligDULE REQUIREMENTS Comed requests approval of this license amendment request prior to startup of LaSalle, Ur.it 1, from its current forced outage, L1F35, cu rently scheduled for April 2,1998. The amendment should be made effective upon issuance for Unit 1. Comed will implement the amendment prior to startup of LaSalle, Unit 1 from the current outage.

A-21

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