ML20155D810

Summary of 860401 Meeting W/Utils Re Resolution of Issue of Interlocks for ECCS Injection Valves Which Also Function as Pressure Isolation Valves.Viewgraphs & List of Attendees Encl

ML20155D810
Person / Time
Site:	Grand Gulf
Issue date:	04/08/1986
From:	Kintner L Office of Nuclear Reactor Regulation
To:	Office of Nuclear Reactor Regulation
References
TAC-59440, NUDOCS 8604170437
Download: ML20155D810 (21)

Text

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s, p*!t%'o g UNITED STATES 8 o I4UCLEAR REGULATORY COMMISSION E, WASHINGTON, D. C. 20555

% **.** #} APR 8W Docket no. 50-416 LICENSEE: Mississippi Power & Light Comapny (MP&L)

FACILITY: Grand Gulf Nuclear Station, Unit 1

SUMMARY

OF APRIL 1, 1986 MEETING REGARDING INTERLOCKS FOR ECCS PRESSURE ISOLATION VALVES The purpose of the meeting was to discuss resolution of an issue regarding interlocks for ECCS injection valves which also function as pressure isolation valves. Enclosure 1 is a list of attendees. Enclosure 2 is a handout prepared by the licensee. Enclosure 3 is a November 22, 1985 staff letter which defines the issue.

Prior to the meeting, the licensee had proposed Technical Specification changes (by letter dated August 12,1985) to implement a design change to add interlocks to the ECCS injection valves to prevent over pressurization of the low pressure coolant injection systems by the higher pressure reactor coolant system due to inadvertant opening of the valves. The licensee had proposed to include inter-locks for the automatic opening of the valves by a LOCA signal, but not to include interlocks for manual controls on the remote shutdown panel. Further the licensee had proposed to use a set point for the interlocks that was 110% of the reactor piping system design pressure, as defined in the ASME Code. The staff had deter-mined that the proposed design criteria, as supplemented by letters dated September 25, October 5 and October 22, 1985, were unacceptable and provided its position and alternative acceptable criteria by letter dated November 22, 1985 (Enclosure 3).

During the meeting, the licensee summarized its remote shutdown panel (RSP) design criteria, using the information presented in Enclosure 2 as an outline. The licensee stated that the SRP is not designed with the same philosophy concerning interlocks as is the control room control circuits (e.g., a pressure permissive is not required for the corresponding RSP control circuit). The RSP rooms contain only RSP equipment and each electrical division is in a separate room. Access to the rooms is administratively controlled by locked doors. Circuits in the panels are normally energized. There are only a few interlocks on valve controls on the remote shutdown panel and these are valve-to-valve interlocks and not

. pressure activated interlocks as associated with various control room circuits.

Other features are outiineo in Pages 3-6 of Enclosure 2.

. The licensee's position is that because of the security provided for these RSP rooms and infrequent use and access and because of training of operators who are authorized to use the panels, inadvertant operation of these ECCS valves from the RSP is unlikely and pressure permissive interlocks should not be required.

Regarding the set points for interlocks on control room circuits, the licensee's position is that the 1974 ASME Code for which Grand Gulf is designed allows tran-sients to raise the system pressure to 110% of design pressure (sizing and setting 8604170437 860408 PDR ADOCK 05000416 P PDR ,

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relief valves for overpressurization transients). The 1977 ASME Code which first addressed setpoints for interlocks and specifies use of design pressure for the set point is not a requirement for the Grand Gulf plant because the construction permit was issued in 1974. The licensee has estimated that lowering the interlock setpoint 50 psi to the design pressure of the low pressure system would increase the calculated peak cladding temperature following a LOCA by 6 F (to 2157'F) and that this would unnecessarily reduce the margin to the limiting 2200 F thus reducing the margin available for operational enhancements. The licensee's position is summarized on Page 2 of Enclosure 2. The calculation of the interlock setpoints is shown on Page 7 of Enclosure 2.

At the conclusion of the meeting, the licensee proposed alternative positions which are similar to the alternative positions indic~ated in staff's November 22, 1985 letter (Enclosure 3). The licensee proposed the use of key lock switches at the remote shut down panel (not the motor control center) because of the poor access of the motor control center if operation of the ECCS valves was needed for shut down. The licensee indicated that they were confident the low design pressure ECCS systems could withstand 110% of design pressure for the transients resulting from a LOCA or inadvertant manual opening of the valves during plant heatup or cooldown. However, the licensee did not believe the major analytical effort necessary to increase the ASME Code design pressure rating by 50 psi was needed. The staff said it would consider the information presented in the meeting and inform the licensee of its conclusion by telephone.

By telephone on April 3,1986, the staff informed the licensee that the alter-natives proposed in the April 1, 1986 meeting appeared to be acceptable. The staff indicated that the key locked control switches should be separate from the present spring-return-to-auto control switches and that relevant infor-mation regarding design of the switches and administrative controls should be provided in the supplemental letter. The staff also said that a statement should be provided to the effect that pressures equivalent to the upper analytical limit of the setpoint will satisfy ASME Code stress allowable values for the piping, valves and other components of the ECCS systems.

L. L. Kintner, Project Manager '

BWR Project Directorate No. 4 Division of BWR Licensing Enclcsures:

As stated ct: See next page

relief valves for overpressurization transients). The 1977 ASME Code which first addressed setpoints for interlocks and specifies use of design pressure for the set point is not a requirement for the Grand Gulf plant because the construction permit was issued in 1974. The licensee has estimated that lowering the interlock setpoint 50 psi to the design pressure of the low pressure system would increase the calculated peak cladding temperature following a LOCA by 6 F (to 2157 F) and that this would unnecessarily reduce the margin to the limiting 2200 F thus reducing the margin available for operational enhancements. The licensee's position is summarized on Page 2 of Enclosure 2. The calculation of the interlock setpoints is shown on Page 7 of Enclosure 2.

At the conclusion of the meeting, the licensee proposed alternative positions which are similar to the alternative positions indicated in staff's November 22, 1985 letter (Enclosure 3). The licensee proposed the use of key lock switches at the remote shut down panel (not the motor control center) because of the poor access of the motor control center if operation of the ECCS valves was needed for shut down. The licensee indicated that they were confident the low design pressure ECCS systems could withstand 110% of design pressure for the transients resulting from a LOCA or inadvertant manual opening of the valves during plant heatup or cooldown. However, the licensee did not believe the major analytical effort necessary to increase the ASME Code design pressure rating by 50 psi was needed. The staff said it would consider the information presented in the meeting and inform the licensee of its conclusion by telephone.

By telephone on April 3, 1986, the staff informed the licensee that the alter-natives proposed in the April 1,1986 meeting appeared to be acceptable. The staff indicated that the key locked control switches should be separate from the present spring-return-to-auto control switches and that relevant infor-mation regarding design of the switches and administrative controls should be provided in the supplemental letter. The staff also said that a statement should be provided to the effect that pressures equivalent to the upper analytical limit of the setpoint will satisfy ASME Code stress allowable values for the piping, valves and other components of the ECCS systems.

Orleind siened ty L. L. Kintner, Project Manager BWR Project Directorate No. 4 Division of BWR Licensing Enclosuret:

As stated

. DISTRIBUTION cc: See next page . Docket. File- ACRS(10)

NRC POR NRC Participants local PDR PD#4 Reading

- WButler

/ LKintner PD#4 PM PD#4/D [ Young, OELD LKintner:lb WButler i EJordan 04/[/86 04 /86'4 BGrimes

Mr. Oliver D. Kingsley, Jr.

Mississippi Power & Light Company Grand Gulf Nuclear Staiton ec:

Robert B. McGehee, Esquire The Honorable William J. Guste, Jr.

Wise, Carter, Child, Steen and Caraway Attorney General .

P.O. Box 651 Department of Justice Jackson, Mississippi 39205 State of Louisiana Baton Rouge, Louisiana 70804 Nicholas S. Reynolds, Esquire Bishop, Liberman, Cook, Purcell Office of the Governor and Reynolds State of Mississippi 1200 17th Street, N.W. Jackson, Mississippi 39201 Washington, D. C. 20036 Attorney General 1 Mr. Ralph T. Lally Gartin Building i Manager of Quality Assurance Jackson, Mississippi 39205 Middle South Services, Inc.

P.O. Box 61000 Mr. Jack McMillan, Director New Orleans, Louisiana 70161 Division of Solid Waste Management Mississippi Department of Natural Mr. Larry F. Dale, Director Resources Nuclear Licensing and Safety Bureau of Pollution Control Mississippi Power & Light Company Post Office Box 10385 P.O. Box 23054 Jackson, Mississippi 39209 Jackson, Mississippi 39205 Alton B. Cobb, M.D.

Mr. R. W. Jackson, Project Engineer State Health Officer Bechtel Power Corporation State Board of Health 15740 Shady Grove Road P.O. Box 1700 Gaithersburg, Maryland 20877-1454 Jackson, Mississippi 39205 Mr. Ross C. Butcher President Senior Resident Inspector Claiborne County Board of Supervisors U.S. Nuclear Regulatory Commission Port Gibson, Mississippi 39150 Route 2, Box 399 i Port Gibson, Mississippi 39150 Mr. Ted H. Cloninger Vice President, Nuclear Engineering Regional Administrator, Region II and Support U.S. Nuclear Regulatory Commission, Mississippi Power & Light Company 101 Marietta Street, N.W., Suite 2900 Post Office Box 23054 Atlanta, Georgia 30323 Jackson, Mississippi 39205 9

Mr. J. E. Cross Grand Gulf Nuclear Station Site Director Mississippi Power & Light Company P.O. Box 756 Port Gibson, Mississippi 39150 Mr. C. R. Hutchinson GGNS General Manager l Mississippi Power & Light Company '

Post Office Box 756 Port Gibson, Mississippi 39150 y - _-

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Enclosure 1 ATTENDEES NRC - MP&L Meeting - April 1, 1986 .

NRC MP&L l L. L. Kintner Sam H. Hobbs Charles C. Graves Wayne Russell Wayne Hodges Thomas Barnett Jim Lombardo Mike Withrow Horace Shaw Joe Hendry W. Butler

• J.C. Catlin, Jr.

B. Si'egel*

M. Srinivasan* i Bob Stevens Illinois Power Company P. J. Telthorst l

• Part time i 4 l

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Enclosure 2 LOW PRESSURE ECCS PRESSURE PERMISSIVE INTERLOCK MEETING AGENDA MP&L/NRC BETHESDA, MARYLAND APRIL 1, 1986 I. OVERVIEW 0F ISSUES REQUIREMENT OF LICENSE CONDITION 2.C.(18)

NO INTERLOCKS ON RSP LPCI/LPCS SETPOINT AB0VE 500 PSIG i GGNS COMMITMENTS /NRC SAFETY EVALUATIONS CURRENT INDUSTRY PRACTICES II. REMOTE SHUTDOWN PANEL

-III. LPCI/LPCS SETPOINT AB0VE 500 PSIG IV. MP&L'S POSITION J16 MISC 86031301 - 1

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.(. l III. MP&L'S POSITION DESIGN CHANGE GOES BEYOND THE DESIGN BASIS OF GG

1) INSTALLATION OF INTERLOCKS TO THE VALVE CONTROL CIRCUITS IN THE REMOTE SHUTDOWN PANEL TECH SPEC CHANGE DOES COMPLY WITH SRP 7.4 4

TECH SPEC SETPOINT DOES COMPLY WITH GGNS SSER2, SECTION 6.3.4 e

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• MPal HAS AND ALWAYS WILL UTILIZE ACCEPTABLE INDUSTRY PRACTICES PURSUANT TO ASME CODE PCT INCREASE OF 6*F NOT NECESSARY l

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II. GGNS REMOTE SHUTDOWN PANEL (RSP)  !

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DESIGN BASIS .

CONFIGURATION 1 .

RSP OPERATION J

1 GGNS REMOTE. SHUTDOWN PANEL /JMD/l 3

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GGNS RSP DESIGN BASIS RSP REQUIRED BY 10CFR50, APPENDIX A, GDC 19 RSP UTILIZED FOR SHUTDOWN WITH CONTROL ROOM UNINHABITABLE .

DESIGN BASIS ACCIDENTS ASSUMED NOT TO OCCUR CONCURRENT WITH CONTROL ROOM EVACUATION AUTOMATIC CONTROLS CONTINUE TO FUNCTION AFTER EVACUATION RSP CONTROLS OPERATE IN PARALLEL WITH CONTROL ROOM CONTROLS RSP CONTROLS DESIGNED TO BE COMPATABLE WITH CONTROL ROOM CIRCUITS .

RSP CONTROLS DESIGNED FOR MANUAL SHUTDOWN I

i GGNS' REMOTE SHUTDOWN PANEL /JMD/2 -

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GGNS RSP CONFIGURATION TWO BASIC TYPES OF CONTROL CIRCUITS 4

NORMALLY ENERGIZED RSP ARRANGEMENT / ADVANTAGES l RSP LOCATIONS / DETAILS l1 4

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GGNS REMOTE SHUTDOWN PANEL /JMD/3 -

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GGNS RSP OPERATION 4

ACCESS CONTROLS PROCEDURES

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i GGNS REMOTE SHUTDOWN PANEL /JMD/4 b

PRESSURE INTERLOCK SETPOINTS FOR LOW PRESSURE ECCS AUT0r1ATIC INITI ATION UPPER ANALYTICAL LIMIT ==<============== 550 psig Adj ustments for inst. loop accuracy and calibration allowances MAX. ALLOWABLE YALUE ==1(============= 534 psig

( Tech. Spec. Setpoint )

Adjustments for drift and leave-as-is margin NOMINAL TRIP SETPOINT ==lf============= 516 psig

( Tech. Spec. Setpoint )

Adjustment for system

, static head NTS including system head = = ^c ^ =

correction = =)(============= 489 psig

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Additional adjustments to NTS (higher or lover) for inst. Acceptable setpoint range head correction as required LOWER NTS ==)(============= 470 psig Adjustments for drift and leave-as-is margin LOWER ALLOWiBLE VALUE ==

A=n=========== 432 psig (Tech, Spec Setpoint)

Adjustments for inst. loop accuracy and calibration allovences LOWER ANALYTICAL LIMIT ==n============= 436 psig f

7

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8-A1 UNITED STATES Enclosure 3

NUCLEAR REGULATORY COMMISSION s

p .W ASHINGTON, D. C. 20555

\ . . . . . *#g November 22, 1985 Docket No.: 50-416 Mr. Jackson B. Richard Senior Vice President Mississippi Power and Light Company P.O. Box 23054 Jackson, Mississippi 39205

Subject:

Grand Gulf Unit 1 - Low Pressure Emergency Core Cooling System (ECCSI Pressure Permissive Interlocks By letter dated August 12, 1985, Mississippi Power and Light Company requested an amendment to the Grand Gulf Nuclear Station, Unit I operating license in order to implement a design change which would add pressure permissive interlocks to the control circuits for low pressure ECCS injection valves. This change is required by License Condition 2.C.(18) to be implemented prior to startup following the first refueling. Technical Specification changes proposed to implement this design change were proposed in Item 13 of the Attachment to the August 12, 1985, letter.

During its review of the proposed Technical Specification changes, the NRC l staff requested additional information regarding the pressure interlocks.  !

The licensee provided some of the requested information, including a revised  !

ECCS performance analysis (by letter dated October 22,1985), a description '

of the logic incorporated in the pressure permissive interlocks and a piping and . instrument diagram (by letter dated October 5,1985), and a proposed surveillance requirement on ECCS valve opening time (by letter dated September 25, 1985). However, the licensee declined to provide additional information regarding:

(1) the addition of interlocks to the valve control circuits in the remote shutdown panel or alternate means to minimize the potential for inadvertent overpressurization of the low design pressure systems, and (2) changing the interlock pressure setpoints to values below the ECCS piping design pressure.

The purpose of this letter is to request additional information and to provide the NRC staff's safety evaluation and position regarding interlocks for ECCS valve controls on remote shutdown panels and the pressure setpoint for inter-locks on low design pressure ECCS piping. The staff's safety evaluation and  !

positions, including acceptable alternatives to interlocks on tho remote shut-down panel, is enclosed.

The staff concludes that the proposed Technical Specification change in Item 13 of tho licensee's August 12, 1985, letter, as supplemented by letters dated September 25, October 5, and October 22, 1985, is unacceptable because it does not meet the NRC staff position regarding pressure N

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. Novemb r 22, 1985 Mr. Jackson B. Richard pennissive interlocks for the remote shutdown panel cont Review interlocks Plan do notSection meet the 7.4.III),

staff positand because the proposed setrol circuits below the ECCS piping design pressure (ion requiring interlock setpoints t Evaluation Supplement 2, Section 6.3.4, NUREG-0831) Grand Gulf Nuclea to the enclosed staff positions.You are requested to revise Item Based on its preliminary review, the NRC s license in the manner proposed in the August 12 issue

, 1985, submittal. mend the operating i

The staff will resultingreissue theevaluation.

from its safety notice in this matter due n to the need of receipt of this letter.this letter in the new notice, you should submi significant hazards conditions for any revised 50.91 (a) of 10 CFR 50. proposal purs o Section letter, of the 12, the August staff intends 1985, letter. to deny the request for licensIn the absen e amendment in Item 13 Sincerely, Thomas Novak, Assistant Director 'i for licensing {

Enclosure:

Division of I.icensing i As stated cc: See next page i.

m , +

Mr. Jackson B. Richard Mississippi Power & Light Company Grand Gulf Nuclear Staiton cc:

Robert B. McGehee, Esquire The Honorable William J. Guste, Jr.

Wise, Carter, Child, Steen and Caraway Attorney General P.O. Box 651 Department of Justice Jackson, Mississippi 39205 State of Louisiana Baton Rouge, Louisiana 70804 Nicholas S. Reynolds, Esoufre Bishop, Liberman, Cook, Purcell Mr. Oliver D. Kingsley, Jr.

and Reynolds Vice President, Nuclear Operations 1200 17th Street, N.W. Mississippi Power & Light Company Washington, D. C. 20036 P.O. Box 23054 Jackson, Mississippi 39205 Mr. Ralph T. Lally ,

j Manager of Quality Assurance Office of the Governor Middle South Services, Inc. State of Mississippi P.O. Box 61000 Jackson, Mississippi 39201 New Orleans, Louisiana 70161 Attorney General Mr. Larry F. Dale, Director Gartin Building

, Nuclear Licensing and Safety Jackson, Mississippi 39205 Mississippi Power & Light Company P.O. Box 23054 Mr. Jack McMillan, Director l Jackson, Mississippi 39205 Solid Waste Mississippi State Board of Health Mr. R. W. Jackson, Project Engineer 880 Lakeland Bechtel Power Corporation Jackson, Mississippi 39206 15740 Shady Grove Road Gaithersburg, Maryland 20760 A lton B. Cobb, M.D.

State Health Officer Mr. Ross C. Butcher State Board of Health Senior Resident Inspector P.O. Box 1700 U.S. Nuclear Regulatory Commission Jackson, Mississippi 39205 '

Route 2, Box 399 Port Gibson, Mississippi 39150 President Claiborne County Board of Supervisors Regional Administrator, Region II Port Gibson, Mississippi 39150 U.S. Nuclear Regulatory Commissior,,

101 Marietta Street, N.W., Suite 2900 Atlanta, Georgia 30323 Mr. J. E. Cross, General Manager Grand Gulf Nuclear Station Mississippi Power & Light Company P.O. Box 756 Port Gibson, Mississippi 39150

Enclosure SAFETY EVALUATION GRAND GULF UNIT 1 LOW PRESSURE ECCS SYSTEM PRESSURE PERMISSIVE INTERLOCKS Facility Operating License NPF-29, Condition 2.C.(18) requires the licensee to implement isolation protection against overpressurization of the low pressure emergency core cooling systems (RHR/LPCI and LPCS) through the implementation of reactor vessel pressure permissive interlocks. The licensee has proposed Technical Specification (T.S.) changes t'o support the required design change.

The Instrumentation and Control Systems Branch (ICSB) focused its review on the revisions to T.S. Tables 3.3.3-1 and 4.3.3.1-1. The Reactor Systems Branch with the assistance of the Mechanical Engineering Branch focused its attention on systems and piping design aspects of the proposed changes.

Instrumentation and Control Systems Aspects The licensee proposes to include the new high/ low pressure permissive inter- -

locks for the low pressure ECCS injection valves in T.S. Table 3.3.3-1 (ECCS Actuation Instrumentation). The Technical Specifications will require a minimum of three channels operable for all operating conditions with Action 31 (declare ADS trip system or ECCS inoperable) applicable for Operating Conditions 1, 2, and 3 and Action 35 (trip inoperable channel after one hour or declare associated systems inoperable) applicable for Operating Conditions 4 and 5. Upon request, the licensee provided information (Letter dated October 5,1985) to clarify what constitutes a channel for the pressure gm n ~ 4 ys IV\WVd I /

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2 pennissive interlocks. The licensee states that the minimum requirement of 3 operating channels per trip function is applicable to the "one-out-of-two twice" logic utilized in the design change and is adequate to assure operability of the required low pressure injection function considering the diversity of injection systems and logic channels available (four per trip function).

The licensee also proposes to add the surveillance requirements for the new interlock channels to T.S. Table 4.3.3.1-1 (ECCS Actuation Instrumentation Surveillance Requirements). The surveillance frequencies will be once per 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> for channel check, once per month for channel functional test, and once per refueling cycle for channel calibration for all operating conditions.

Based on the above information, the staff finds the channel operability require-ments proposed for revised T.S. Table 3.3.3-1 to be acceptable. We also find the channel surveillance frequencies proposed in T.S. Table 4.3.3.1-1 to be acceptable.

After implementation of the proposed design, the high/ low pressure. permissive interlocks for the low pressure ECCS injection valves will be active for both automatic and manual control room operaticn. The licensee has proposed not to include such an interlock for.the remote shutdown panel (RSP) control circuits for the ECCS injection valves. Based on the current information provided by the licensee, the staff finds the requested interlock omission to be unacceptable.

a .

It is the staff's position that pressure permissive interlocks should be installed as part of the RSP control circuits consistent with the corresponding control room control circuits. This position is based on the Standard Review Plan (SRP Section 7.4) interpretation of GDC 19 which requires that the remote shutdown station equipment be designed to the same standards as the corre-sponding equipment in the main control room. Also, Section 6.3.4 of the Grand Gulf, Unit 1 SER Supplement No. 2 requires that interlocks be present at all times for both manual and automatic actuation unless the reactor vessel pressure is lower than the design pressure of the ECCS involved. Thus, without special control over the operation of these valves, inadvertent operation must l

~

be assumed from the RSP which could resu1t in overpressurization of the low

] pressure ECCS.

The following is an acceptable alternative (method of special control) to the implementation of pressure permissive interlocks for the RSP control circuits associated with the low pressure ECCS injection valves:

(1) the provision of spring-return-to-normal control switches on

, the RSPs which would alleviate the concern related to the change-of-state of equipment upon transfer of control to the RSP and

^

(2) (A) Continue to implement special Technical Specification 4.4.3.2.2.b for LPCS and LPCI outboard check valves to ensure integrity since the licensee takes credit for these valves as part of the omission justification, or

(B) Implementation of a keylocked control switch separate from the RSP controls (preferably at.MCC) which would block operation of the valve via the RSP control. This should include administrative controls to ensure that RSP control of the valve is actually blocked when the valve is closed.

Also, valve position indication should not be negated in the control room or at the RSP by the implementation of this special control scheme.

Systems and Piping Design

• The licensee has proposed Technical Specification (TS) changes regarding the low pressure ECCS injection system, in response to an NRC position regarding the prevention of an intersystem LOCA which was expressed in Supplement No. 2 to the Grand Gulf Nuclear Station (GGNS) Safety Evaluation Report (NUREG-0831) and which became License Condition 2.C.(18).. These TS changes would implement design changes adding pressure interlocks to the injection valves on the low pressure ECCS systems, require respective trip setpoints, and require periodic surveillance of associated ECCS actuation instrumentation.

Two of the proposed changes are administrative in nature. For instance, in connection with the installment of pressure interlocks, an additional trip function has been added to the ECCS low pressure systems. The minimum number of operable channels, applicable operational conditions, and action to be

taken are supplied for the new trip function (see Tables I and 2). Instru-mentation surveillance intervals are also designated for this function (see Table 3). These proposals are acceptable to us, as discussed above.

In the original submittal, MP&L proposed to delete ECCS response times for low pressure systems. Subsequently, in a letter dated September 25, 1985, MP&L proposed to use "f 29 seconds" as response times for both LPCI and LPCS injection valves. This is acceptable to us because this response time is within the value used in analyses of loss of coolant accidents.

One issue that has not been resolved is the interlock setpoint for the high pressure to low pressure interface valve. The setpoint 534 psig, is above the design pressure of the low pressure system, 500 psig. The ASME Code, dated 1977, which was the first Code edition to address such interlocks, required the interlocks to prevent the pressure from exceeding the design pressure of the low pressure side. Section 6.3.4 of GGNS SSER's (June 1982),

states that the valves in question should be " interlocked to prevent opening unless the reactor vessel pressure is lower than the design pressure of the 1

ECCSs involved." From discussions with the licensee, we understand that main-taining the setpoint below the design pressure will result in increased peak cladding cemperature for the postulated loss ok ,a,c.;A e-~T cident from 2151*F to )/

2157*F, which is still less than the limiting value of 2200 F required by 10 CFR 50.46.

The staff concludes that exceeding the Code allowable design

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pressure for the interlocks is unacceptable because the Code position can be

, =y e e u . >

i met without reducing the acceptable margin of safety for-peak cladding temperature.

If meeting the Code requirement results in a hardship, the hardship should be described and justification should be provided for our consideration. Include in the justification the results of an analysis to show that pressure in the ECCS piping equal to the upper analytical limit of the interlock setpoint will satisfy the ASME Code stress allowable values for the piping, valves and other components of the affected portions of the ECCS.

1 4