ML20070N585

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Proposed Tech Specs Re Max Allowable Power Range Neutron Flux High Setpoint When One or More Main Steam Safety Valves Inoperable
ML20070N585
Person / Time
Site: South Texas  STP Nuclear Operating Company icon.png
Issue date: 04/29/1994
From: Groth J
HOUSTON LIGHTING & POWER CO.
To:
Shared Package
ML20070N583 List:
References
NUDOCS 9405090020
Download: ML20070N585 (12)
v • d • e


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ATTACHMENT 3

( PROPOSED TECHNICAL SPECIFICATION CHANGES l

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l 9405090020 940429 PDR ADOCK 05000498 P PDR TS0*94\94-116.001 I

TSI -145JM TABLE 3.7-1 MAXIMUM ALLOWABLE POWER RANGE NEUTRON FLUX HIGH SETPOINT WITH INOPERABLE STEAM lit 4E SAFETY VALVES DURING 4 LOOP OPERATION KnIMUM NUMBER OF IN0PE ABLE MAXIMUM ALLOWABLE POWER RANGE SAFETY VALVES ON ANY NEUTRON FLUX HIGH SETPOINT OFERATING STEAM GENERATdR (PERCENT OF RATED THERMAL POWER) 1 Bf b3 2 -Gr, A/6' 3 e 27 2

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1 SOUTH TEXAS - UtilTS 1 & 2 3/4 7-2

ATTACHMENT A - CHANGE TO BASES g, 100)(W,hqN)

Q K where:

Hi 4 = Safety analysis power range high neutron flux setpoint, percent Q = Nominal NSSS power rating of the plant (including reactor coolant pump heat), MWt K = Conversion Factor, 947.82 (BTU /sec) /MWt w, = Minimum total steam flow rate capability of the operable MSSVs on any one steam generator at the highest MSSV opening pressure, including tolerance and accumulation, as appropriate, in lbm/sec. For example, if the maximum number of inoperable MSSVs on an3 one steam generator is one, then w, should be a summation of the capacity of the operable MSSVs at the highest operable MSSV operating pressure, excluding the highest capacity MSSV. If the maximum number of inoperable MSSVs per steam generator is three, then w, should be a summation of the capacity of the operable MSSVs at the highest operable MSSV operating pressure, excluding the three highest capacity MSSVs.

hrg = Heat of vaporization for steam at the highest MSSV operating pressure including allowances for tolerance, drift, and accumulation, as appropriate Btu /lbm N = Number of loops in the plant.

The calculated values a1 awered an additional 9% full power to account for instrument ana channel uncertainties.

t TSC-94\94-116.001

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'3/4.7 PLANT SYSTEMS MiES 3/4.7.1 TURBINE CYCLE 3/4.7.1.1 SAFETY VALVES The OPERABILITY of the main steam line' Code safety valves ensures that the Secondary System p'ressure will be limited to within 110% (1413.5 psig) of its design pressure of 1285 psig during the most severe anticipated system operational transient. The maximum relieving capacity is associated with a Turbine trip from 100% RATED THERMAL POWER coincident with an assumed loss of condenser heat sink (i.e., no steam bypass to the condenser).

The specified valve lift settings and relieving capacities are in accordance with the requirements of Section III of the ASME Boiler and Pressure Code, 1971 Edition. The total relieving capacity for all valves on all of the steam lines is 20.65 x 106 lbs/h which is 122% of the total second-ary steam flow of 16.94 x 106 lbs/h at 100% RATED THERMAL POWER. A minimum of two OPERABLE safety valves per steam generator ensures that sufficient reliev-ing-capacity is available for the allowable THERMAL POWER restriction in Table 3.7-1.

STARTUP and/or POWER OPERATION is allowable with safety valves inoperable within the limitations of the ACTION requirements on the basis of the reduc-tion in Secondary Coolant System steam flow and THERMAL POWER required by the  ;

reduced Reactor trip settings of the Power Range Neutron Flux channels. The Reactor Trip Setpoint reductions are' derived on the following bases:

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--109 - Pcwcr Rcng Neut+en-F4ex-High-THp-Setpoint for-four-loop-L--operati on, X - Tet:1 relieving capa, city cf all cafety-valves-pe'r-ster 'l line in lb:/heurr-and-

--Y =

"exibub relieving cepecity of eny one setety vel.c in l

-lbs/ hour '

SOUTH TEXAS - UNITS 1 & 2 B 3/4 7-1

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i ATTACHMENT 4 1

JUSTIFICATION FOR CONTINUED OPERAI' ION

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TSC 94\94 116.001

4 h STP 724 (02/90)

! SOUTH TEXAS PROJECT ELECTRIC GENERATING STATION "" T-

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IP-1.58Q 2 INTERDEPARTMENTAL PROCEDURES

{ PAGE 15 or 17 Preparation of Justificatiens for Continued Operation hNE AUG 0 41992 i

j ATTACHMENT IP-1.58Q-01

) JCO APPROVAL COVER SHEET 4 (Page 1 of 1) l

  • j JCO Approval Cover Sheet 4

i Expiration Date (Unit 1) e2!20f9 7 3

(Unit 2) J/Jo/97

Subject:

owEl SANGE NEoTRoN FLvX N!Qfl SLTf%/Mr WITM INcPERABtl NSSh 3 JCO No. M- 000) Revision No.

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j Applicable Units: Ik2.

i Summary: be o los3 J !=rt / +u4N 4rto cue ^4. \Aleshkl.w kc s debM

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efAlte M d ce vie.1 va f e Ce 579) ik:s 'Uro la ad 751-145) OnNid, R rev.'s,d 3df' Preparedby/Date;pf .[- m / 7 /!#)

Organization, Matyiger // ba t'e Responsible fd( JCO Concurrence With/Date: ,

d / 3f1f 44 General Manage [, Nucl//tr Licensing ' Date l

Recorrnended by PORC Meeting No./Date: 44-031 z 3l?A H  !

i Approved /Date: MiJf/4/

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'Pl' ant ManageY'

  • /" ' / Date Related Document Reference Numbers: SPR H020%

LCTS NSAL 94-co t \

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l IPi!P-1-58Q.R2

i JCO 94-0001, POWER RANGE NEUTRON FLUX HIGH SETPOINT WITH INOPERABLE MAIN STEAM SAFETY Valves, Revision 1 REASON FOR REVISION This JCO is being revised to incorporate the increased Allowed Outage Time (AOT) for Technical Specification 3.7.1.1 (Steam Generator Safety Relief Valves) from 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> to 24 3

hours. The AOT extension was approved by the NRC as Amendment 59 to the Unit 1 Operating License and Amendment 47 to the Unit 2 Operating License.

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JCO 94-0001, POWER RANGE NEUTRON FLUX HIGH SETPOINT WITH lNOPERABLE MAIN STEAM SAFEq VALVES, Revision 1 TABLE OF CONTENTS 1.0 ID ENTIFIC ATION . . . . . . . . . . . . . . . . . . . . . . ...................... ... 1 2.0 OPERATION .................................. ................. 1 3.0 SAFETY FUNCTION . . . . . . . . . .............. ...................... 2 4.0 S A F ETY A N ALYS I S . . . . . . . . . . . . . . . . . . . ............. . ...... .. 2 5.0 REQUIRED COMPENSATORY ACTIONS . . . .... . . .. . .......... 3 6.0 CORRECTIVE ACTION ........... ......... . .... .... . . ..... 3 7.0 REPORTING . . . . ... .. .. ............. .. ........... ...... 3

8.0 REFERENCES

...... .... ............ .. . .......... .... ... 4 1

ATTACHMENT A, "JCO OPERATIONAL IMPACT STATEMENT" .. ... .... . .. 5  ;

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JCO 94-0001, POWER RANGE NEUTRON Flux HIGH SETPotNT WITH INoPEnABLE MAIN STEAM SAFETY VALVES, Revision 1 Expiration Date: JCO No. 94-0001, Rev.1. will expire on 2/20/97 for STP Units 1 and 2. l 1 1.0 IDENTIFICATION Westinghouse Nuclear Safety Advisory Letter (NSAL)94-001, dated 1/20/94, concems operation at reduced power levels with inoperable Main Steam Safety Valves (MSSVs).

Technical Specification Table 3.7-1 allows the plant to operate with a reduced number of operable MSSVs at a reduced power level. For a loss of load / turbine trip event, Westinghouse has determined that the maximum allowable power range neutron flux high setpoints given in Table 3.7-1 may not be low enough to preclude a secondary side overpressurization condition. SPR 940289 was initiated on 2/04/94 to address this issue. In the SPR, Engineering recommended that until this matter is resolved, rated thermal power be reduced to 10% in the event a MSSV becomes inoperable. The requirements posed by this JCO supersede the recommendation in SPR 940289.

In NSAL 94-001, Westinghouse provided an algorithm to determine revised neutron flux high setpoints to be used instead of the Technical Specification Table 3.7-1 values. Using this algorithm, Nuclear Fuel & Analysis (Thermal Hydraulics division) has performed design calculation NC-7104, ' Power Range High Neutron Flux Setpoint With Inoperable MSSVs,' to determine the revised values. Should one or more MSSVs become inoperable, the power I range high neutron flux setpoint shall be reduced to the values provided in Section 5.0 and i Attachment A of this JCO. l The setpoints provided in Table 3.7-1 have been errant since the Technical Specifications have been in place. A review of the Westinghouse Standard Technical Specifications shows that this error was made by Westinghouse and it affects other Westinghouse plants as well.

The reason for this problem is not known at this time.

2.0 OPERATION There are five spring-loaded MSSVs on each Main Steam line, required for protection of the steam generators and steam lines against overpressurization. To avoid lifting during pressure transients, the set pressures for the MSSVs are as high as possible within the code requirements. To prevent valve chattering during operation of the safety valves, the individual valves in each Main Steam line are set at different pressures. The MSSV design is in accordance with ASME B&PV Code, Section Ill, Subsection NC.

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4 JCO 94-0001, POWER RANGE NEUTRON Flux HIGH SETPOINT WITH INOPERABLE MAIN STEAM SAFETY VALVES, Revision 1 3.0 SAFETY FUNCTION The safety function of the MSSVs is to protect the steam generators and the piping upstream of the Main Steam isolation Valves from overpressure under all modes of operation. During a loss of loadf turbine trip, operability of the MSSVs ensures that the secondary system pressure will be limited to within 110% (1413.5 psig) of its design pressure of 1285 psig. The NRC has concluded in Section 10.3.1 of the STP Safety Evaluation Report (SER) that the Main Steam system from the steam generators through the Main Steam isolation Valves meets 10CFR50, Appendix A, General Design Criterion (GDC) 2, Design bases for protection against naturalphenomena; GDC 4, Environmental and dynamic effects design bases; GDC 5, Sharing of stnictures, systems, and components; and GDC 34, Residual heat removal with respect to protection against natural phenomena, missiles, sharing, environmental effects, l and residual heat removal; Regulatory Guide (RG) 1.29 Positions C.1 and C.2, and RG 1.117 Positions C.1 and C.2, relating to the Main Steam system's seismic classification and

! protection against tornado missiles; and Branch Technical Position RSB 51 and issue No.1 of NUREG-0138 related to safe shutdown from the control room using only safety-grade l

equipment and main steam isolation following a line break. Therefore, the NRC has l concluded that the Main Steam system is acceptable and meets Standard Review Plan l Section 10.3.

4.0 SAFETY ANALYSIS Using a revised algorithm provided by Westinghouse in NSAL 94-001, Nuclear Fuel &

Analysis (Thermal Hydraulics division) has performed calculation NC-7104, " Power Range High Neutron Flux Setpoint With inoperable MSSVs," to determine the revised values for Technical Specification Table 3.7-1. The revised algorithm ensures that the maximum power level allowed for operation with inoperable MSSVs is below the heat removing capability of the MSSVs. Included in the revised setpoints is a 9% power reduction to account for instrument and channel uncertainties. Therefore, following a loss of load / turbine trip, the revised maximum plant operating power levels will ensure that the secondary system pre sure will be limited to within 110% of its design pressure.

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JCO 94-0001, power RANGE NEUTRON FLUX HIGH SETPolNT WITH INOPERABLE MAIN STEAM SAFETY VALVES, Revision 1 5.0 REQUIRED COMPENSATORY ACTIONS Action / Measure Description Responsible Org. Implementing Doc. Complete Schedule in Modes 1,2, and 3 with one Plant Operations TSI-145 Yes N/A inoperable safety valve on any l operating steam generator, reduce the I

maximum allowable power range neutron flux high cetpoint to 63% rated thermal power.

In Modes 1,2, and 3 with two Plant Operations TSI-145 Yes N/A inoperable safety valves on any operating steam generator, reduce the maximum allowable power range neutron flux high setpoint to 45% rated thermal powar.

n. Modes 1,2, and 3 with three Plant Operations TSI145 Yes N/A inoperable safety valves on any operating steam generator, reduce the maximum allowable power range neutron flux high setpoint to 27% rated thermal power.

6.0 CORRECTIVE ACTION

1. Nuclear Fuel & Analysis, in conjunction with Nuclear Licensing, will prepare a proposed Technical Specification change to Table 3.7-1 to incorporate the reduced maxirnum allowable power range neutron flux high setpoints.

Corrective Action 1 will be completed by March 31,1994. After NRC approval of the proposed Technical Specification change, this JCO will no longer be required, and the maximum power level allowed for operation with inoperable MSSVs will be below the heat removing capability of the MSSVs.

7.0 REPORTING This section addresses the need for reporting under 10CFR50.72 and 10CFR50.73, as well as potential 10CFR21 concems. A reportability review for SPR 940289 (ST-HS-HS-27822, dated 2/11/94) shows that this issue is not reportable pursuant to 10CFR50.72 and 10CFR50.73.

Westinghouse stated in NSAL 94-001 that this issue does not represent a substantial safety (c3docsVnssv'mssv 2 lco - amr)

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l 0 94-0001, POWER RANGE NEUTRON Flux HIGH SETPOINT NTH INOPERABLE MAIN STEAM SAFETY VALVES. Revision 1 hazard for STP pursuant to 10CFR21. Nuclear Fuel & Analysis concurs with Westinghouse's conclusion.

8.0 REFERENCES

1. NSAL 94-001; ' Operation at Reduced Power Levels with Inoperable MSSV's;'

January 20,-1994; transmitted via ST-WN-HS 94-205 from M. A. Sinwell to J. J. Sheppard on January 20,1994.

2. Station Problem Report 940289; February 4,1993.
3. NC-7104; ' Power Range High Neutron Flux Setpoint With inoperable MSSVs;'

February 11,1994.

4. NUREG-0781; " Safety Evaluation Report Related to the Operation of South Texas Project, Units 1 and 2;" April 1986.
5. ST-HS-HS-27822; 'SPR 94-0289, ' Power Range Neutron Flux High Setpoint With inoperable Main Steam Safety Valves,' Reportability Review;' February 11,1994; D. A. Leazar to Unit 1 Shift Supervisor.
6. ST AE-HL-93719; ' Issuance of Amendment Nos. 59 and 47 to Facility Operating License Nos. NPF-76 and NPF-80 and Related Relief Requests - South Texas Project, Units 1 and 1 2;' February 17,1994; S. C. Black (USNRC) to W. T. Cottle.

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JCO 94-0001, POWER RANGE NEUTRON Flux HIGH SETPolNT WITH lNOPERABLE MAIN STEAM SAFETY VALVES. Revision 1 ATTACHMENT A, "JCO OPERATIONAL IMPACT STATEMENT" i l

JCO # 94-0001, Revision 0 JCO

Title:

Power Ranae Neutron Flux Hiah Setpoint With inoperable Main Steam Safety Valves A. To maintain the validity of this JCO, Operations must do the following:

1. In Modes 1,2, and 3, with four reactor coolant loops and associated steam generators in operation and with one or more main steam line Code safety valves inoperable, operation in Modes 1,2, and 3 may proceed provided that within i

24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />, either the inoperable valve is restored to OPERABLE status or the Power l1  ;

Range Neutron Flux High Trip Setpoint is reduced per the following table: I MAXIMUM NUMBER OF INOPERABLE SAFETY MAXIMUM ALLOWABLE POWER RANGE NEUTRON FLUX VALVES ON ANY STEAM GENERATOR HIGH SETPOINT (% OF RATED THERMAL POWER) 1 63 2 45 3 27 otherwise, be in at least HOT STANDBY within the next 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> and in COLD SHUTDOWN within the following 30 hours3.472222e-4 days <br />0.00833 hours <br />4.960317e-5 weeks <br />1.1415e-5 months <br />.

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