ML20059G905

TS Change Request 91-03-0 to Licenses NPF-39 & NPF-85, Revising TS to Eliminate Main Steam Line Radiation Monitoring Sys High Radiation Trip Function for Initiating & Automatic Closure of Main Steam Line Isolation Valves

ML20059G905
Person / Time
Site:	Limerick
Issue date:	10/29/1993
From:	Hunger G PECO ENERGY CO., (FORMERLY PHILADELPHIA ELECTRIC
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
Shared Package
ML20059G907	List: ML20059G905 ML20059G915
References
NUDOCS 9311090179
Download: ML20059G905 (19)

Text

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10~CFR 50.90 PHILADELPHIA ELECTRIC COMPANY NUCLEAR GROUP HEADQUARTERS 955-65 CHESTERBROOK BLVD.

WAYNE. PA 19087-5691 (215) 640-f030 October 29, 1993 Docket Nos. 50-352 STATION SUPPORT DEPARTMENT License Nos. NPF-39 NPF-85 i

U.S. Nuclear Regulatory Coamission Attn: Document Control Desk Washington, DC 20555

Subject:

Limerick Generating Station, Units 1 and 2 Technical Specifications Change Request Gentlemen:

Philadelphia Electric Company (PEco) is submitting Technical Specifications (TS) Change Request No. 91-03-0, in accordance with 10 CFR 50.90, requesting an amendment to the TS (i.e., Appendix A) of Operating License Nos. NPF-39 and NPF-85 for Limerick Generating Station (LGS), U.its 1 and 2, respectively. This proposed TS change involves revising the 1S to eliminate the Main Steam Line Radiation Monitoring (MSLRM) system high raJiation trip function for initiating

1) an automatic reactor scram and automatic closure of the Main Steam Line Isolation Valves (MSIVs), and 2) automatic closure of the Main Steam line drain valves, and Main Steam and Reactor Water sample line valves. The MSLRM system high radiation trip function for the Mechanical Vacuum Pump (MVP) will be retained. The justification for eliminating the MSLRM system high radiation trip functions for initiating an automatic reactor scram and automatic closure of the M0iVs is based on the evaluation provided in General Electric's (GE's) Topical Report NED0-31400A, " Safety Evaluation for Eliminating the Boiling Water Reactor Main Steam Line Isolation Valve Closure Function and Scram Function of the Main Steam Line Radiation Monitor." This topical report was reviewed and approved by the NRC as documented in its letter dated May 15, 1991, in which the NRC .

indicated that this topical report would be acceptable for referencing by licensees requesting TS changes concerning the elimination of the MSLRM high radiation trip functions.

The elimination of the MSLRM system high radiation trip function for initiating an automatic closure of the Main Steam Line drain valves and Main Steam and Reactor Water sample line valves was not considered in the NEDO-31400A analysis and therefore, additional information is provided to substantiate these specific proposed TS changes.

Information supporting this TS Change Request is contained in Attachment I to this letter, and the proposed replacement pages for the LGS, Units 1 and 2, TS are contained in Attachment 2.

08n032 9311090179 931029 F PDR ADDCK 05000352- I' P S\

PDR- b \-

U.S. Nuclear Regulatory Commissien OctCber 29, 1993 Document Control Desk Page 2 i

We request that, if approved, the amendments to the LGS, Units 1 and 2, f be effective within 30 days following issuance of the amendments.

t If you have any questions, please do not hesitate to contact us. f l l l >

Very truly yours, f

-lgfOV ~

G. A. unger, r.

_ Director Licensing Section l Attachments cc: T. T. Martin, Administrator, Region I, USNRC (w/ attachments) l

. N. S. Perry, USNRC Senior Resident Inspector, LGS (w/ attachments) 1 W. P. Dornsife, Director, PA Bureau of Radiological Protection (w/ attachments) i i

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COMMONWEALTH OF PENNSYLVANIA:  ;

ss.

COUNTY OF CHESTER  : l G. R. Rainey, beinig first duly sworn, deposes and says:

i That he is Vice President of Philadelphia Electric Company; the Applicant f herein; that he has read the foregoing Application for Amendment for Facility Operating License Nos. NPF-39 and NPF-85 (Technical Specifications Changes Request No. 91-03-0) to eliminate the Main Steam Line Radiation Monitor system J

high radiation trip function for initiating an automatic reactor shutdown, automatic closure of the Main Steam Isolation Valves, Main Steam line drain  !

valves, and Main Steam and Reactor Water sample line valves at Limerick Generating Station, Units 1 and 2, and knows the contents thereof; and that the statements and matters set forth therein are true and correct to the best of his i

knowledge, information, and belief.

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Vice P esident l

Subscribed and swa to before me this 4D day of4 $16 bh 1993.

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ATTACHMENT 1 LIMERICK GENERATING STATION UNITS 1 AND 2 i

Docket Nos. 50-352 50-353 License Nos. NPF-39 NPF-85 TECHNICAL SPECIFICATIONS CHANGE REQUEST No. 91-03-0

" Revise Technical Specifications to Eliminate the Main Steam Line Radiation Monitor System High 'Asdiation Trip Function for Initiating an Automatic Reactvr Scram and Automatic Closure of the Main Steam Line I' solation Yalves, Main Steam Line Drain Valves, and Main Steam and Reactor Water Sample Line Valves

• Supporting Information for Cnanges - 13 pages

. . Attachment-1  !

, Page 1 l '

L Philadelphia Electric Company (PECo), Licensee under Facility Operating License Nos. NPF 39 and NPF-85 for Limerick Generating Station (LGS), Units 1 and -

2, respectively, requests that the Technical Specifications (TS) contained in l- Appendix A to the Operating Licenses be amended as proposed herein, to revise the TS to eliminate the Main Steam Line Radiation Monitor (MSLRM). system high radiation trip function for initiating _1) an automatic reactor scram - and  !

automatic closure of the Main Steam Line Isolation Valves (MSIVs), and 2)  :

automatic closure of the Main Steam Line Drain valves, and Main Steam and Reactor i Water sample line valves. t l

The proposed TS changes involve revising the following TS Sections and '

Bases to reflect elimination of the MSLRM system high radiation trip function. 1 TS Tables - 2.2.1-1, 3.3.1-1, 4.3.1.1-1, 3.3.1-2, 3.3.2-1, )

3.3.2-2, 3.3.2-3, 4.3.2.1-1, and 3.6.3-1. '

i Bases Sections - 2.2.1.5, 2.2.1.6, 3/4.3.1, and 3/4.3.2. )

l In addition, TS Bases page B 3/4 3-3 was also revised since it was i necessary to relocate a portion of the information contained in Bases Section 3/4.3.3, " Emergency Core Cooling System Actuation Instrumentation," from page 3/4 3-2 to 3/4 3-3 to accommodate the proposed TS changes.

The proposed TS changes associated with eliminating the MSLRM system high radiation trip function for initiating an automatic reactor scram and automatic closure of the MSIVs are being implemented in accordance with the guidance delineated in General Electric's (GE's) Topical Report NED0-31400A, " Safety Evaluation for Eliminating the Boiling Water Reactor Main Steam Line Isolation Valve Closure Function and Scram Function of the Main Steam Line Radiation Monitor," which was approved by the NRC by letter dated May 15, 1991.

The proposed TS changes to eliminate the automatic closure of the Main Steam line drain valves and Main Steam and Reactor Water sample line valves on a MSLRM system high radiation signal were not evaluated in GE Topical Report NED0-31400A and therefore, additional information is provided to support these proposed changes.

The proposed changes to the TS are indicated by a vertical bar in the margin of the affected TS pages. The TS pages showing the proposed changes are contained in Attachment 2.

I i We request that, if approved, the amendments to the LGS, Units 1 and 2, TS be effective within 30 days following issuance of the amendments.

This TS Change Request provides- a discussion and description of the proposed TS changes, a safety assessment of the proposed TS changes, information l supporting a finding of No Significant Hazards Consideration, and information  !

supporting an Environmental Assessment. l l

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. . Attachment 1 Page 2 Discussion and Descriotion of the Proposed Chances The Main Steam Line Radiation Monitoring (MSLRM) system is designed to monitor radiation levels in the Main Steam lines, since high radiation emanating from the Main Steam lines could indicate a gross release of fission products from the fuel. This system monitors for the gross release of fission products from the fuel and, upon indicatico of such a release, initiates system isolations and a reactor trip to limit fuel damage and contain the released fission products. l The MSLRM system consists of four (4) gamma-sensitive instrument channels which monitor gamma radiation levels in the four (4) Main Steam lines. The radiation detectors installed in the MSLRM system are physically located near the Main Steam lines just downstream of the outboard Main Steam Line Isolation Valves (MSIVs). These detectors are geometrically arranged to detect significant increases in gamma radiation levels with any number of the Main Steam lines in l operation. The detector locations along the Main Steam lines allows for the  ;

earliest practicable detection of a gross fuel failure. The detectors' high radiation trip setting is selected high enough above full reactor power background radiation levels to prevent spurious isolation, yet low enough to l promptly detect a gross release of fission products from the fuel. j i

When a significant increase in the Main Steam line radiation level is detected, the MSLRM system transmits signals to the Reactor Protection System (RPS) ar.d the Primary Containment and Reactor Vessel Isolation Control System (PCRVICS). Upon receipt of a high radiation signal, the RPS initiates an automatic reactor scram and the PCRVICS initiates an automatic closure of all a MSIVs, Main Steam line drain valves, and Main Steam and Reactor Water sample line l valves.

The proposed TS changes involve eliminating the MSLRM system high radiation j trip function for initiating I) an automatic reactor scram and automatic closure of the MSIVs, and 2) automatic closure of the Main Steam line drain valves and l Main Steam and Reactor Water sample line valves. These proposed changes support installation of a plant modification to defeat portions of MSLRM high radiation i trip function logic circuitry in the RPS and PCRVICS. Installation of this  :

modification will not impct the operation of the RPS or PCRVICS with respect to

performing its other intended safety functions. The MSLRM system high radiation trip function for the Mechanical Vacuum Pump (MVP) will be retained. The proposed TS changes involve deleting specific TS requirements associated with the MSLRM system high radiation trip functions contained in the Isolation Actuation Instrumentation and RPS Instrumentation TS tables. In addition, the applicable TS Bases sections will be revised to reflect the elimination of the MSLRM high radiation trip functions. The following is a list of the specific changes included in this proposed TS Change Request.

1) TS Table 2.2.1-1 (Reactor Protection System Instrumentation Setpoints) - Delete setpoint requirements for " Main Steam Line Radiation - High" (i.e., Table Item 6).

2) TS Bases 2.2.1 (Reactor Protection System Instrumentation

, Setpoints), Item 5 - Delete reference to " . . .high steam line

! radiation...."

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- Attachment 1 l Page 3 l

3) TS Bases 2.2.1 (Reactor Protection System Instrumentation Setpoints), Item 6 - Delete reference to " Main Steam Line Radiation j

- High." j l

4) TS Table 3.3.1-1 (Reactor Protection System Instrumentation) -

Delete operational condition requirements for " Main Steam Line Radiation - High" (i.e., Table Item 6).

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5) TS Table 3.3.1-2 (Reactor Protection System Response Times) - Delete response time requirement for " Main Steam Line Radiation - High" (i .e. , Table Item 6) . '

6) TS Table 4.3.1.1-1 (Reactor Protection System Instrumentation Surveillance Requirements) - Delete surveillance requirements for i

" Main Steam Line Radiation - High" (i.e., Table Item 6).

7) TS Table 3.3.2-1 (Isolation Actuation Instrumentation) - Delete operational condition requirements for " Main Steam Line Radiation -

High" (i.e., Table Item 1.b).

8) TS Table 3.3.2-2 (Isolation Actuation Instrumentation Setpoints) -  !

Delete setpoint requirements for " Main Steam Line Radiation - High" (i.e., Table Item 1.b).

9) TS Table 3.3.2-3 (Isolation System Instrumentation Response Time) -

Delete response time requirements for " Main Steau Line Radiation -

High" (i.e., Table Item 1.b).

10) TS Table 3.3.2-3 (Isolation System Instrumentation Response Time) -

Delete " Table Notation" Item (b) regarding response time testing of '

radiation detectors.

11) TS Table 4.3.2.1-1 (Isolation Actuation Instrumentation Surveillance Requirements) - Delete surveillance requirements for " Main Steam Line Radiation - High" (i.e., Table Item 1.b).

12) TS Table 4.3.2.1-1 (Isolation Actuation Instrumentation Surveillance i

Requirements) - Delete table note "####" concerning Main Steam Radiation trip function.

13) Table 3.6.3-1 (Part A - Primary Containment Isolation Valves) -

Delete isolation signal reference designation (i.e., "D") for " Main Steam Line Radiation - High" for the penetrations specified below.

- 007A(B,C,D) - Main Steam Line (A, B, C, D) l - 008 - Main Steam Line Drain

- 028A Recirculation loop Sample

- 043B - Main Steam Sample l

. Attachment 1 Page 4

14) Table 3.6.3-1 (Part B - Primary Containment Isolation Excess Flow Check Valves) - Delete isolation signal reference designation (i.e.,

"D") for " Main Steam Line Radiation - High" for the penetration specified below. .

- 007A(B,C,D) - Main Steam Line Pressure .

15) Bases Section 3/4.3.1 (Reactor Protection System Instrumentation) -

Add statement indicating that the MSLRM system high radiation trip function for initiating an automatic reactor scram was eliminated.

16) Bases Section 3/4.3.2 (Isolation Actuation Instrumentation) - Add statement indicating that the MSLRM system high radiation trip function for initiating automatic closure of the Main Steam Line Isolation Valves (MSIVs) was eliminated, i The justification for eliminating the MSLRM system high radiation trip ,

function for initiating an automatic reactor scram and automatic closure of the MSIVs is based on General Electric's (GE's) Topical Report NED0-31400A, " Safety Evaluation for Eliminating the Boiling Water Reactor Main Steam Line Isolation Valve Closure Function and Scram Function of the Main Steam Line Radiation Monitor," ano applicability of this report to LGS, Units 1 and 2. This GE '

topical report provides the safety assessment for eliminating the MSLRM system high radiation trip function for initiating an automatic reactor scram and automatic closure of the MSIVs and demonstrates that the reactor vessel isolation function and scram function of the MSLRM system are not required to ensure compliance with the requirements of 10CFR100. By letter dated May 15, 1993, the .

NRC approved this GE topical report and indicated that it would be acceptable for  !

licensees to reference this report when submitting TS changes concerning the elimination of the MSLRM system high radiation trip functions provided that the guidance and limitations specified in NED0-31400A and associated NRC Safety Evaluation Report (SER) are followed.

The proposed TS changes associated with eliminating the MSLRM high radiation trip function for initiating automatic closure of the Main Steam line  :

drain valves, and Main Steam and Reactor Water sample line valves were not evaluated in NEDO-31400A. We propose to eliminate the MSLRM system high radiation automatic closure function for these valves on the basis that the Main Steam line drain valves ultimately discharge to main condenser, whereby non-condensable gases are extracted and processed through the Offgas Treatment system prior to release to the environment. Since the discharge from these valves enters the main condenser and is processed through the Offgas Treatment system the analysis provided in NED0-31400A is applicable. With respect to the Main .

Steam and Reactor Water sample line valves, the sample lines are routed to  ;

sample sinks where inlet valves are normally closed. In addition, sample line

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valves must be periodically opened to facilitate chemistry sampling.

Safety Assessment The Main Steam Line Radiation Monitoring (MSLRM) system is designed to monitor radiation levels in the Main Steam lines, since high radiation levels emanating from these lines could indicate a gross release of fission products

h i

. Attachment I  !

Page 5 i from the fuel. This system monitors for the gross release of fission products i from the fuel and, upon indication of such a release, initiates system isolations j and a reactor trip to limit fuel damage and contain the released fission products.

Th NSLRM system consists of four (4) gamma-sensitive instrument channels which monitor gamma radiation levels in the four (4) Main Steam lines. The radiation detectors installed in the MSLRM system are physically located near the Main Steam lir.es just downstream of the outboard Main Steam Line Isolation Valves -

(MSIVs). These detectors are geometrically arranged to detect significant '

increases in gamma radiation levels with any number of the Main Steam lines in  ;

operation. The MSLRM system radiation detectors are set to initiate a. Main Control Room (MCR) annunciation alarm when Main Steam line radiation levels reach ,

or exceed 1.5 times the full reactor power background level. At three (3) times ,

full reactor power background levels, these detectors will initiate trip signals to automatically shut down the reactor and close the MSIVs. The detector locations along the Main Steam lines allow for the earliest practicable detection of a gross fuel failure. The high radiation trip setpoint (i.e., three (3) times-full reactor power background) for these detectors was established at a high enough value above full reactor power background radiation levels to prevent  !

spurious reactor scrams and Main Steam line isolations, yet low enough' to promptly detect a gross release of fission products from the fuel. However, in  !

establishing this setpoint no consideration was given for the potential of-  !

spurious reactor trips from Nitrogen-16 spikes (i.e., an isotope created in _the l coolant as it flows through the reactor core), instrument instabilities, and other operational occurrences. ,

When a significant increase in the Main Steam line radiation level (i.e., l above the setpoint values) is detected, the MSLRM system initiates MCR alarms and transmits signals to the Reactor Protection System (RPS) and the Primary Containment and Reactor Vessel Isolation Control System (PCRVICS). Upon receipt  !

of a MSLRM high radiation signal, the RPS initiates an automatic reactor scram l and the PCRVICS initiates an automatic closure of all MSIVs, Main Steam line ,

drain valves, and Main Steam and Reactor Water sample line valves. >

These proposed TS changes support installation of a plant modification to defeat portions of MSLRM system high radiation trip function logic circuitry in the RPS PCRVICS. Installation of this modification will not impact the operation of the RPS or PCRVICS with respect to performing its other safety functions. The.  :

MSLRM system high radiation trip function for the Mechanical Vacuum Pump (MVP)  :

will be retained.

The MSLRM system high radiation trip function is not credited in any design basis accident analysis. A Control Rod Drop Accident (CRDA), a design basis l accident, does assume that the MSLRM system initiates a MSIV closure on high radiation; however, no credit was taken for closure of the MSIVs in reducing the ,

radiological consequences of this event as the analysis assumes that all 4

radioactive material calculated to be available for release is transported to the  ;

main condenser before the MSIVs close.

Elimination of the MSLRM high radiation trip functions for initiating an automatic reactor scram and automatic closure of the MSIVs in based on the safety l analysis provided in General Electric (GE) Topical Report NED0-31400A, " Safety 1

. . Attachment 1 ,

Page 6 Evaluation for Eliminating the Boiling Water Reactor Main Steam Line Isolation Valve Closure Function and Scram Function of the Main Steam Line Radiation Monitor," and the applicability of this report to Limerick Generating Station i (LGS), Units I and 2. By letter dated May 15, 1993, the NRC approved NED0-31400A and indicated that it would be acceptable for licensees to reference this report when submitting TS changes concerning the elimination of the MSLRM system high  ;

radiation trip functions provided that the guidance and limitations specified in ,

this report and associated NRC Safety Evaluation Report (SER) are followed.

As documented in the Topical Report, NED0-31400A, there have been a number of spurious actuations of the MSLRM system at other plants causing unnecessary automatic reactor shutdowns. These shutdowns were the result of instrument failures, reactor coolant chemistry excursions, radiation monitor maintenance errors, and other causes; but none from the detection of failed fuel. NEDO- : 31400A documents the conclusion that the MSLRM system high radiation trip function for initiating an automatic reactor scram and automatic closure of the l MSIVs is not requ! red to ensure compliance with the radiation dose limitation  ;

requirements stipulated in 10CFR100. NED0-31400A indicates that removing the MSLRM system high radiation reactor scram and MSIV closure functions will reduce i the potential for unnecessary reactor shutdowns and will increase plant i operational flexibility since the main condenser will remain available for decay '

heat removal. In addition, this topical report demonstrates that the Offgas  :

Treatment system provides significant holdup times for radionuclides, and that I use of this system is an acceptable method for controlling unexpected radioactive l material releases. Eliminating the MSLRM system trip functions in conjunction  ;

with proper operation of the Offgas Treatment system will ensure that any l radioactive material released to the environment is a small fraction of 10CFR100 1 limits.

The MSLRM system high radiation MCR alarms and the trip function for isolating the Mechanical Vacuum Pump (MVP) will be retained. This will ensure that any radioactive material released from a fuel failure will be contained in the main condenser and processed through the Offgas Treatment system. The Offgas Treatment system continuously removes non-condensable gases from the main condenser by the Steam Jet Air Ejectors (SJAEs) during plant operation. The offgas extracted from the main condenser consists of activation gases, fission product gases, radiolytic hydrogen and oxygen, and condenser air inleakage. The Offgas Treatment system is designed to reduce offgas radioactivity levels to permissible levels for release under all site atmospheric conditions. The system uses catalytic recombination for volume reduction and control of hydrogen concentration and activated charcoal filters to adsorb fission product and activation gases prior release to the environment. The Offgas Treatment system is monitored at appropriate locations for flow, temperature, pressure, humidity, conductivity, radiation, and hydrogen concentration. Sufficient instrumentation is provided to permit system operation and monitoring from the MCR. Radiation monitors are located upstream of the system's holdup volume pipe to continuously monitor gaseous radioactive material input to the charcoal adsorption filters.

This provides a representative indication of the gaseous radioactive material released from the reactor core and therefore, fuel integrity. Provision is made for grab sampling of the influent gases to the charcoal filters for the purpose of determining isotopic composition of the influent gases. In addition, a radiation monitor is provided at the outlet of the charcoal adsorption filter beds to continuously monitor effluent gases released from the filters. l

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- Attachment 1 Page 7 Elimination of the MSLRM system high radiation trip functions for )

initiating automatic closure of the Main Steam line drain valves and Main Steam and Reactor Water sample line valves were not evaluated in NED0-31400A. The flow from the Main Steam line drain valves ultimately travels to the main condenser  !

i just as the flow from the MSIVs. Therefore, any radioactive material passing l l

through the Main Steam line drain valves to the main condenser and through the Offgas Treatment system is treated identically to any radioactive material that would pass through the MSIVs. Since NED0-31400A evaluated removing the MSLRM system high radiation trip function for closing the MSIVs, this same analysis can be applied for closure of the Main Steam line drain valves. With respect to deleting the MSLRM high radiation trip function to close the Main Steam and Reactor Water sample line valves on a MSLRM system high radiation signal, the effects are negligible since these lines are small in comparison to the size of the lines associated with the MSIVs and Main Steam line drains. Furthermore, the sample lines are routed to a sample sink where inlet valve on the sample lines are normally closed. Downstream of the inlet valves, the fiow through the sample lines is controlled and limited to a small amount by the needle valves. The flow 1 indicator for the Main Steam sample line has a maximum reading of 700 cc/ min.

The sample sink is located in the Reactor Enclosure and is enclosed, and_ vented air is filtered prior to release to the environment. The Reactor Enclosure l ventilation duct radiation monitor samples air from the sample sink hood exhaust, and will isolate the Reactor Enclosure ventilation system if the radiation levels exceed the monitor's setpoint. In addition, the sample line valves must be periodically opened to facilitate sampling of the Main Steam and Reactor Water.

In the unlikely event that the Main Steam sample line inlet valve is open, and ,

the throttling needle valve is fully open, a minimal amount of radioactive i material would be released to the environment. However, we have determined that I the whole body dose received at the exclusion area boundary through this flowpath over a 30 day period would be 5.14E-02 rem as a result of the release of ,

radioactive isotopes of Xenon and Krypton (i.e., radioactive isotopes of Iodine I are adsorbed in the vent duct charcoal filter). This represents less than 1% of

! the whole body dose of six (6) rem as stipulated in NUREG-0800, Standard Review i l

Plan (SRP), Section 15.4.9, Appendix A, " Radiological Consequences of Control Rod  !

Drop Accident (BWR)," and assures that any release would be a small fraction of j the dose limit requirements specified in 10CFR100. '

Finally, in a letter dated May 15, 1991, the NRC stated that removal of the MSLRM system high radiation trip function for initiating an automatic reactor scram and closure of the MSIVs is acceptable; however, licensees referencing l NED0-31400A in support of their TS change requests must meet the following conditions. Therefore, each condition is restated below followed by our response.

Condition 1 The applicant demonstrates that the assumptions with regard to input 4 values (including power per assembly, Chi /Q, and decay times) that are j made in the generic analysis bound those for the plant.  ;

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Attachment 1 Page 8

Response

Section 15.4.9, " Control Rod Drop Accident," of the LGS Updated Final Safety Analysis Report (UFSAR) refers the Identification of Causes, Sequence of Events and System Operation, Mathematical Model and Inpat Parameters of the Control Rod Drop Accident (CRDA) to Section S.2 of NEDE-24011, General Electric Standard Application for Reactor Fuel (i.e.,

GESTAR II). The Design Basis Analysis is based on SRP Section 15.4.9.

The Design Basis Analysis assumes the failure the failure of 770 fuel rods. The mass fraction of the fuel in the damaged rods which reaches or exceeds fuel melting is estimated at 0.77%. The fuel is assumed to release 100% of the noble gas inventory and 50% of the iodine inventory.

Of the radioactive material released,100% of the noble gases and 10% of the iodines are assumed to be carried over to the main condenser before the MSIVs completely close. The calculated exposures from the Design Basis Analysis are well within the dose limit requirements of 10CFR100.

The analysis provided in NED0-31400A assumes that the CRDA results in the failure of 850 fuel rods with a mass fraction of fuel in the damaged rods of 0.77%. Fission product releases are consistent with those identified in SRP Section 15.4.9. For the portion of the fuel which was assumed to reach the melting point, the release fractions were 100% of the noble gases and 50% of the iodines.

A comparison between the Chi /Q values presented in the LGS UFSAR and NED0-31400A, show that the design basis assumption values in NED0-31400A are more conservative than that in the LGS UFSAR. Therefore, we have determined that the CRDA analysis for LGS, Units 1 and 2, is bounded by the GE analysis provided in NED0-31400A.

Condition 2 ,

i The applicant includes sufficient evidence (implemented or proposed  !

operating procedures, or equivalent commitments) to provide reasonable j assurance that increased significant levels of radioactivity in the main '

steam lines will be controlled expeditiously to limit both occupational doses and environmental releases.

Response

Appropriate actions will be implemented at LGS to ensure that significant increases in Main Steam line radiation levels are adequately controlled to limit occupational exposures and environmental releases. In the event of a MSLRM system high radiation alarm, MSLRM and Offgas Treatment system radiation level trending data from radiation monitor recorders will be reviewed, and if necessary, reactor coolant samples will be obtained and analyzed. If high radiation levels are confirmed, as measured by the Offgas Treatment system radiation monitors, reactor power will be reduced to maintain offgas release rates within TS requirements. If these release rWes can not be maintained within required TS limits, an orderly plant shutdown will be initiated. Plant procedures will be in place to implement the appropriate mitigative measures in response to a MSLRi1 system high radiation alarm signal.

i Attachment 1-  !

Page 9 l

Condition 3 P

The applicant standardizes the MSLRM and offgas radiation monitor. alarm  ;

setpoint at 1.5 times the normal Nitrogen-16 background dose rate at the i monitor locations, and commits to promptly sample the reactor coolant to  :

determine possible contamination levels in the plant reactor coolant and  ;

the need for additional corrective actions, if the MSLRM or offgas i radiation monitors or both exceed their alarm setpoints.  !

Response

The MSLRM alarm setpoint is currently set at 1.5 times the expected full  !

reactor power background radiation level. Therefore, the MSLRN alarm - -

setpoint does not need to be reset. The Offgas Treatment system radiation '

monitor high radiation setpoint is currently set at 2,100 mR/hr in  ;

accordance with GE's recommendation. This setpoint value will be  !

reevaluated based on the NRC's recommendations. ~ This setpoint' will be  !

lowered if we determine that the current 2,100 mR/hr value is too high. i As previously indicated in our response to Item 2 above, samples will be.

taken, as necessary, to ascertain reactor coolant chemistry conditions. j Information Supportina a Findino of No Sionificant Hazards Consideration We have concluded that the proposed changes to the Limerick Generating Station (LGS), Units 1 and 2, Technical Specifications (TS) and associated Bases ,

to eliminate the Main Steam Line Radiation Monitor (MSLRM) high radiation trip  !

functions for initiating 1) an automatic reactor scram and automatic closure of )

the Main Steam Line Isolation Valves (MSIVs), and 2) automatic closure of the )

Main Steam Line drain valves, and Main Steam and Reactor Water sample line valves -j do not involve a Significant Hazards Consideration. In support of ' this J determination, an evaluation of each of the three (3) standards set forth in 10 CFR 50.92 is provided below.

, 1. The proposed Technical Specifications (T9 chances do not involve a sionificant increase in the orobability or conseouences of an accident Dreviously evaluated.

The proposed TS changes involve eliminating the Main Steam Line Radiation Monitoring (MSLRM) system high radiation trip function for initiating an automatic' reactor scram and automatic closure of the- i Main Steam Line Isolation Valves (MSIVs), Main Steam line drain-valves, and Main Steam and Reactor Water sample line valves. The proposed TS changes support installation of a plant modification to defeat portions of MSLRM system high radiation trip function logic circuitry in the Reactor Protection System (RPS) and Primary

i. Containment and Reactor Vessel Isolation Control System (PCRVICS).

Installation of this modification will not adversely impact the operation of the RPS or PCRVICS with respect to performing its other intended safety functions. The proposed TS changes will not affect the operation of other plant systems or equipment important to

. Attachment I Page 10 safety. The MSLRM system high radiation trip function for the Mechanical Vacuum Pump (MVP) will be retained. The safety assessment and justification for eliminating the MSLRM system high radiation trip function for initiating an automatic reactor scram and automatic closure of the MSIVs is based on General Electric's (GE's) Topical Report NED0-31400A, " Safety Evaluation for Eliminating the Boiling Water Reactor Main Steam Line Isolation ,

Valve Closure Function and Scram Function of the Main Steam Line '

Radiation Monitor," and the applicability of this report to Limerick Generating Station (LGS), Units 1 and 2. By letter dated May 15, 1991, the NRC approved this topical report and indicated that it was acceptable for licensees to reference this report as the basis for  ;

requesting a TS change to eliminate the MSLRM system high radiation  ;

trip functions as documented in the report and associated NRC Safety Evaluation Report (SER).  ;

i The safety assessment provided in NED0-31400A can also be applied to ,

eliminate the MSLRM system high radiation trip function for initiating the automatic closure of the Main Steam line drain valves  !

although this aspect was not explicity evaluated in NED0-31400A. 1 The flow from these valves ultimately discharges to the main  !

condenser as do the MSIVs and therefore, any radioactive material j passing through these valves would be processed in the same fashion i as that passing through the MSIVs. The effects of eliminating the l MSLRM system high radiation trip function for initiating the closure l of the Main Steam and Reactor Water sample line valves is i negligible. The sample lines are routed to a sample sink where  !

inlet valves installed on the sample lines are normally closed.

Additionally, downstream of the inlet valves are needle valves designed to control and limit sample line flow. The sample sink is enclosed, and air vented from its exhaust hood is passed through filters prior to release to the environment. There is the potential that a minimal amount of radioactive material could be released to the environment if the sample sink inlet and needle valves failed to properly function. This potential release has been evaluated and determined to a small fraction of the dose limit requirements specified in 10CFR100.

The MSLRM system high radiation trip was intended to function in response to a Control Rod Drop Accident (CRDA), a Design Basis Accident previously evaluated. Although the CRDA assumes MSIV closure, no credit was taken for this in the CRDA analysis since it postulates that the radioactive material calculated to be released  !

l from the fuel is transported to the main condenser prior to the l MSIVs completely closing. Furthermore, the probability of a fuel failure is independent of the operation of the MSLRM system.

l The Steam Jet Air Ejectors (SJAEs) will continue to operate to l remove non-condensable gases from the main condenser for processing l by the Offgas Treatment system. The Offgas Treatment system will

continue to function as designed to reduce offgas radioactivity levels prior to release to the environment. Eliminating the MSLRM system high radiation isolation functions will improve operational

- Attachment 1 Page 11 I

flexibility in that the main condenser will be available to aid in decay heat removal. Elimination of the MSLRM system high radiation trip functions in conjunction with proper operation of the Offgas Treatment system will ensure that any radioactive material released ,

to the environment is a small fraction of 10CFR100 limits.  !

Therefore, the proposed TS changes associated with eliminating the MSLRM system high radiation trip function for initiating an automatic reactor scram and automatic closure of the MSIVs, Main Steam line drain valves, and Main Steam and Reactor Water sample line valves do not involve an increase in the probability or i consequences of an accident previously evaluated.

2. The orocosed TS chances do not create the possibility of a new or ,

different kind of accident from any accident Dreviously evaluated.

l 1

The proposed TS changes involve eliminating the MSLRM system high l l

radiation trip function for initiating an automatic reactor scram and automatic closure of the MSIVs, Main Steam line drain valves, and Main Steam and Reactor Water sample line valves. The proposed TS changes will not affect the operation of other plant systems or i equipment important to safety. The associated plant modification i simply defeats the MSLRM system high radiation trip function logic '

l circuitry in the RPS and PCRVICS. The RPS and PCRVICS will continue to respond in performing its other design intended safety functions.

The MSLRM system high radiation trip function for the MVP will be retained. The proposed TS changes do not involve any plant hardware changes that could introduce any new failure modes or effects. The MSLRM system radiation monitors will remain active to initiate Main I

Control Room (MCR) annunciation alarms. Plant procedures will be in i

place to implement the appropriate mitigative measures in response to a MSLRM system high radiation alarm signal.

The SJAEs will continue to operate to remove non-condensable gases I from the main condenser for processing by the Offgas Treatment system. The Offgas Treatment system will continue to function as designed to reduce offgas radioactivity levels prior to release to the environment.

Since the Design Basis Accident analysis (i.e., CRDA) does not credit the MSLRM system high radiation trip function for reducing the radiological consequences of the postulated accident, the proposed TS changes have effectively been evaluated and are included in the existing analysis. That is, the CRDA analysis already assumes that the radioactive material released from the failed fuel is immediately transported to the main condenser prior to the MSIVs completely closing.

The safety assessment and assumptions documented in GE Topical i Report NED0-31400A provide the basis for eliminating the MSLRM l system high radiation trip function for initiating an automatic reactor scram and automatic closure of the MSIVs. The safety assessment provided in NED0-31400A can also applied to eliminate the i

i i

- Attachment 1 Page 12 MSLRM system high radiation trip function for initiating the closure  !

of the Main Steam line drain valves, since any radioactive material l passing through these valves would be processed in the same fashion as that passing through the MSIVs. Eliminating the MSLRM system high radiation trip function for initiating the closure of the Main Steam and Reactor Water sample line valves will have a negligible impact. The sample lines are routed to a sample sink where inlet i valves installed on the sample lines are normally closed. i Downstream of the inlet valves are needle valves designed to control and limit sample line flow. The sample sink is located in the Reactor Enclosure and is enclosed, and air vented from its exhaust .

hood is passed through filters prior to release to the environment.

The Reactor Enclosure ventilation duct radiation monitor samples air from the sample sink hood exhaust, and will isolate the Reactor l Enclosure ventilation system if the radiation levels exceed the  !

monitor's setpoint. There is the potential that a minimal amount of  ;

radioactive material could be released to the environment through ,

this flowpath if the sample sink inlet and needle valves failed to  !

properly function. This potential release has been evaluated and l determined to a small fraction of the dose limit requirements i specified in 10CFR100, )

l Therefore, the proposed TS changes do not create the possibility of a new or different kind of accident previously evaluated.

3. The proposed TS chances do not involve a sianificant reduction in a marain of safety.

The proposed TS changes to eliminate the HSLRM system high radiation trip function for initiating an automatic reactor scram and automatic closure of the MSIVs, Main Steam line drains valves, and Main Steam and Reactor Water sample line valves do not change the conclusion reached in the LGS Updated Final Safety Analysis Report (UFSAR) that the calculated radiological consequences of the bounding Design Basis Accident (i.e., CRDA) will not exceed the dose limit requirements established by 10CFR100. The proposed TS changes will improve the overall reliability of the plant when compared to the existing system lineup configuration, since it will reduce the potential of an unnecessary plant transient occurring as a result of an inadvertent MSIV closure.

A reliability assessment analysis was performed to evaluate the effects of eliminating the MSLRM system high radiation reactor scram ,

function on reactivity control failure frequency and core damage i frequency in GE Topical Report NED0-31400A. This analysis indicated that there is a negligible increase in reactivity control frequency with the elimination of the MSLRM trip function. However, this

l l Attachment 1 )

Page 13 increase is compensated for by the reduction in transient initiating l events (i.e., inadvertent reactor scrams). This reduction in l

transient initiating events represents a reduction in core damage j frequency and tht.s, results in a net improvement in safety.

Therefore, the proposed TS changes do not involve a reduction in a margin of safety. j l

l l Information Supoortina an Environmental Assessment An Environmental Assessment is not required for the changes proposed by this Change Request because the requested changes to the Limerick Generating Station (LGS), Units 1 and 2, Technical Specifications (TS) conform to the i criteria for " actions eligible for categorical exclusion," as specified in 10 CFR l 51.22(c)(9). The requested changes will have no impact on the environment. The  !

proposed changes do not involve a Significant Hazards Consideration as discussed l in the preceding section. The proposed changes do not involve a significant I change in the types or significant increase in the amounts of any effluents that may be released offsite. In addition, the proposed changes do not involve a significant increase in individual or cumulative occupational radiation exposure.

Conclusion l The Plant Operations Review Committee and the Nuclear Review Board have reviewed these proposed changes to the Limerick Generating Station (LGS), Units 1 and 2, Technical Specifications (TS) and have concluded that they do not involve an unreviewed safety question, and will not endanger the health and safety of the public.

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