ML17228A652

Proposed Tech Specs Re LTOP Requirements for Power Operated Relief Valves,Per GL 90-06

ML17228A652
Person / Time
Site:	Saint Lucie
Issue date:	07/28/1994
From:	FLORIDA POWER & LIGHT CO.
To:
Shared Package
ML17228A651	List: ML17228A650 ML17228A652
References
GL-90-06, GL-90-6, NUDOCS 9408010287
Download: ML17228A652 (16)

Text

St. Lucie Unit 1.

Docket No. 50-335 Proposed License Amendment ST. LUCIE UNIT 1 MARKER)-UP TECHNICAL SPECIFICATION PAGES Page 3/4 4-59 Insert A Page B 3/4 4-15 9<08O1 0+87 PDR "~o<<

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'REACTOR COOLANT SYSTEM POWER OPERATED RELIEF VALVES

.LIMITING CONDITION FOR OPERATION 3.4.13 Two power operated relief valves (PORVs) shall be OPERABLE, with their

-setpoints selected to the low temperature mode of operation as follows:

a. A setpoint of less than or equal to 350 psia shall be selected:

1. During cooldown when the temperature of any RCS cold leg is less than or equal to 215'F and

2. During heatup and isothermal conditions when the temperature of any RCS cold leg is less than or equal to 193'F.

b. A setpoint of less than or equal to 530 psia shall be selected:

l. During cooldown when the temperature of any RCS cold leg is greater than 215'F and less than or equal to 281'F.

2. During heatup and isothermal conditions when the temperature of any RCS cold leg is greater than or equal to 193'F and less than or equal to 304'F.

PP~N'LITY. MODES 4Md& .

AC 4N:

a. With less than two PORVs OPERABLE and while at Hot Shutdown during a

.p nned cooldown, both PORVs will be returned to OPERABLE status pri to entering the applicable MODE unless:

1. The epairs cannot be accomplished within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> or t repair cannot be performed under hot conditions, or

2. Another a ion statement requires cooldown, or

3. Plant and per nel safety requires cooldown Col'd Shutdown with extreme cau on.

b. With less than two PORVs PERABLE while in D SHUTDOWN, both PORVs will be returned to OPERAB status prior o startup.

c. The provisions of Specificatio 3.0. re not applicable.

SURVEILLANCE RE UIREMENTS 4.4.13 The PORVs shall be verifled+P~fl BLE by:

a. Verifying the isolation vdlges are open whe the PORVs are reset to the low temperatur moIIf of operation.

b. Performance of a $ H NNEL R5 TIONAL TEST of the Re ctor Coolant System overpres 5irization p otection system circuitr up to and including th relief valv solenoids once per refuelin utage.

c. Performs e of a CHAN CALIBRATION of the pressurizer pre ure sensi 9 channels onc per 18 months.

Reac Coolant System co leg temperature below 304'F.

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~ are not required be ow 140'F when RCS does not have pressure boundary ST. LUCIE - UNIT l 3/4 4-59 Amendment 5g. A.

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St. Lucie Unit 1 Docket No. 50-335 Proposed License Amendment LTOP Re uirements for Power 0 crated Relief Valves GL 90-06 INSERT A APPLICABILITY: MODE 4 when the temperature of any RCS cold leg is less than or equal to 304 'F, MODE 5, and MODE 6 when the head is on the reactor vessel; and the RCS is not vented through greater than a 1.75 square inch vent.

ACTIONJ at With one PORV inoperable in MODE 4I restore the inoperable PORV to OPERABLE status within 7 days; or depressurize and vent the RCS through greater than a 1.75 square inch vent within the next 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br />.

b. With one PORV inoperable in MODES 5 or 6, either (1) restore the inoperable PORV to OPERABLE status within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />, or (2) complete depressurization and venting of the RCS through greater than a 1.75 square inch vent within a total of 32 hours3.703704e-4 days <br />0.00889 hours <br />5.291005e-5 weeks <br />1.2176e-5 months <br />.

C~ With both PORVs inoperable, restore at least one PORV to operable status or complete depressurization and venting of the RCS through greater than a 1.75 square inch vent within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />.

d0 With the RCS vented per ACTIONS a, b, or c, verify the vent pathway at least once per 31 days when the pathway is provided by a valve(s) that is locked, sealed, or otherwise secured in the open position; otherwise, verify the vent pathway every 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />.

e. In the event either the PORVs or the RCS vent(s) are used to mitigate an RCS pressure transient, a Special Report shall be prepared and submitted to the Commission pursuant to Specification 6.9.2 within 30 days. The report shall describe the circumstances initiating the transient, the effect of the PORVs or RCS vent(s) on the transient, and any corrective action necessary to prevent recurrence.

f. The provisions of Specification 3.0.4 are not applicable.

SURVEILLANCE REQUIREMENTS 4.4.13 Each PORV shall be demonstrated OPERABLE by:

Verifying the PORV isolation valve is open at least once per 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />; and

b. Performance of a CHANNEL FUNCTIONAL TEST, but excluding valve operation, at least once per 31 days; and c~ Performance of a CHANNEL CALIBRATION at least once per 18 months.

REACTOR COOLANT SYSTEM BASES 3/4.4.13 POWER OPERATED RELIEF VALVES and 3 4.4.14 REACTOR COOLANT PUHP-RTING The low temperature overpressure protection system (LTOP} is designed to prevent RCS overpressurization above the 10 CFR Appendix 6 operating limit curves (Figures 3.4-2a and 3.4-2b) at RCS temperatures at or beTow 304'F. during heatup and 281'F during Cooldown. The LTOP system is based on the use of the pressurizer power-operated relief valves (PORVs) and the implementation of administrative and operational controls.

The PORVs aligned to the RCS with the low pressure setpoints of 350 and 530 psia, restrictions on RCP starts, limitations on heatup and cooldown rates, and disabling of non-essential components provide assurance that Appendix G P/T limits will not be exceeded during normal operation or design basis overpressurization events due to mass or energy addition to the RCS.

3/4.4.15 REACTOR COOLANT SYSTEM VENTS Reactor Coolant System vents are provided to exhaust noncondensible gases and/or steam from the primary system that could inhibit natural circulation core cooling. The OPERABILITY of at least one Reactor Coolant System vent path from the reactor vessel head and the pressurizer steam space ensures the capability exists to perform this function.

The redundancy design of the Reactor Coolant System vent systems serves to minimize the probability of inadvertent or irreverisible actuation while ensuring that a single failure of a vent valve, power supply, or control system does not prevent isolation of the vents path.

The function, capabilities, and testing requirements of the Reactor Coolant System vent system are consistent with the requirements of Item II.b.l of NUREG-0737, "Clarification of TMI Action Plan Requirements," November 1980..

The LTOP system APPLICABILITY, ACTIONS, and SURVEILLANCE REQUIREMENTS are consistent with the resolution of i

Generic Issue 94, "Additional Low-Temperature Overpressure Protection for Light-Water Reactors," pursuant to Generic Letter 90-06.

ST. LUCIE - UNIT 1 B 3/4 4-15 Amendment No. gg,gg, @f,

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St. Lucie Unit 1 Docket No. 50-335 Proposed License Amendment EVALUATION OF PROPOSED TS CHANGES

St. Lucie Unit 1 L-94-153 Docket No. 50-335 Attachment 2 Proposed License Amendment Page 1 of 5 LTOP Re uirements for Power 0 crated Relief Valves GL 90-06 EVALUATION OF PROPOSED TS CHANGES Introduction Florida Power and Light Company (FPL) proposes to change the St.

Lucie Unit 1 Technical Specifications (TS) for the Reactor Coolant System (RCS) Power Operated Relief Valves (PORV). The proposed revision incorporates additional requirements for Low Temperature Overpressure Protection (LTOP) which are similar to those recommended by the NRC staff via Generic Letter 90-06 (GL 90-06).

The TS upgrade is in accordance with the commitment made by FPL in connection with the resolution of Generic Issue 94 (GI-94) for St.

Lucie Units 1 and 2 (FPL Letter L-92-288; 10/9/92).

Back round GL 90-06 was issued by the NRC on June 25, 1990, to advise PWR licensees of staff positions developed during the resolution of Generic Issue 70 (GI-70), "Power Operated Relief Valve and Block Valve Operability," and GI-94, "Additional Low-Temperature Overpressure Protection for Light-Water Reactors." By letters dated December 20, 1990, December 6, 1991, May 11, 1992, and October 9, 1992, FPL responded to GL 90-06 for St. Lucie Units 1 and 2. These letters describe FPL's plan for implementation of recommendations contained in the generic letter.

The NRC reviewed FPL's submittals and found them acceptable (NRC letter dated August 20, 1993). For GI 94, acceptability was based, in part, on a commitment by FPL to submit a change to the St. Lucie Unit 1 TS that is similar to the GL 90-06 specifications for LTOP.

This submittal would be made within one year of receiving staff acceptance of FPL's proposed plan for implementation of the GL 90-06 recommendations.

Descri tion of Chan es The APPLICABILITY, ACTIONS, and SURVEILLANCE REQUIREMENTS of TS 3/4.4.13 have been rewritten in their entirety using the guidance provided for "Modified Technical Specifications for Combustion Engineering and Westinghouse Plants", which is contained in Enclosure B of GL 90-06. Plant specific deviations from the model TS are shown in brackets [].

LCO 3.4.13 APPLICABILITY is changed to read: "MODE 4 when the temperature of any RCS cold leg is less than or equal to 304 F,

St. Lucie Unit 1 L-94-153 Docket No. 50-335 Attachment 2 Proposed License Amendment" Page 2 of 5 LTOP Re uirements for Power 0 crated Relief Valves GL 90-06 MODE 5, and MODE 6 when the head is on the reactor vessel; and the RCS is not vented through greater than a 1.75 square inch vent."

ACTION-a applies to one inoperable PORV when in MODE 4 with the temperature of any RCS cold leg less than or equal to 304 'F.

requires that the inoperable PORV be restored to OPERABLE status It within 7 days; or depressurize and vent the RCS through greater than a 1.75 square inch vent within the next 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br />.

ACTION-b applies to one inoperable PORV when LTOP is required in MODES 5 or 6. It requires that the inoperable PORV be restored to OPERABLE status within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />, or complete depressurization and venting of the RCS through greater than a 1.75 square inch vent within a total of 32 hours3.703704e-4 days <br />0.00889 hours <br />5.291005e-5 weeks <br />1.2176e-5 months <br />.

ACTION-c applies to a condition where both PORVs are inoperable below an RCS temperature of 304 F. It requires that [at least one PORV be restored to operable status or] depressurization and venting of the RCS through greater than a 1.75 square inch vent be completed within [24] hours.

ACTION-d requires that the vent pathway, when established per Actions a, b, or c, be verified at least once per 31 days when the pathway is provided by a valve(s) that is locked, sealed, or otherwise secured in the open position; otherwise the pathway must be verified every 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />.

ACTION-e requires a Special Report to be submitted to the Commission, pursuant to Specification 6.9.2, within 30 days of an event where either the PORVs or RCS vent(s) are used to mitigate an RCS pressure transient.

ACTION-f excludes this Limiting Condition for Operation from the requirements of TS 3.0.4.

SURVEILLANCE RE UIREMENTS are upgraded to require that OPERABILITY of each PORV be demonstrated by verifying the associated PORV isolation valve open at least once per 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />; performing a Channel Functional Test (excluding valve operation) at least once per 31 days'nd performing a Channel Calibration at least once per 18 months.

BASES page B 3/4 4-15 is updated to reflect that TS 3/4.4.13 is consistent with GL 90-06.

St. Lucie Unit 1 L-94-153 Docket No. 50-335 Attachment 2 Proposed License Amendment Page 3 of 5 LTOP Re uirements for Power 0 crated Relief Valves GL 90-06 Evaluation LTOP is provided by the PORVs on the pressurizer. If an RCS pressure transient occurs during low temperature operations, the PORVs are set at pressures sufficiently low to prevent violation of 10 CFR 50, Appendix G, heatup and cooldown curves. The protection range and PORV setpoints selected for LTOP were determined by previous analyses and approved by the NRC via issuance of Amendment No. 104 (6/11/90) to the St. Lucie Unit 1 (PSL1) operating license.

The changes proposed by this submittal do not alter the bases, conclusions, or temperature/pressure range of the previously approved analyses; nor do they alter the LTOP settings which are specified in the existing LCO 3.4.13.

Studies performed for GI-94 show that pressure transients which have challenged the LTOP systems at nuclear power plants have occurred with RCS temperatures in the range of 80 'F to 190 'F.

The NRC staff concluded from these studies that improved administrative restrictions involving Allowed Outage Times (AOT) for inoperable LTOP equipment should be extended to include MODES 5 and 6 when the head is on the reactor vessel, and the RCS is not aligned through an appropriate vent path. The proposed amendment extends APPLICABILITY of TS 3/4.4.13 to the plant conditions that are consistent with the staff's conclusion and does not deviate from the guidance in GL 90-06.

Existing TS 1.16 defines the Low Temperature RCS Protection Range.

Within this definition, the RCS does not have pressure boundary integrity when the RCS is open to containment and the minimum area of the RCS opening is greater than 1.75 square inches. Such an opening is larger than the minimum orifice area (1.354 square inches) of one pressurizer PORV. LTOP analyses for PSL1 demonstrate that one PORV, in conjunction with existing TS constraints on high pressure safety injection pump operability and reactor coolant pump (RCP) starting, has sufficient flow capacity to mitigate the worst case mass and energy transients considered reasonable during the applicable modes. Therefore, the minimum vent size specified by the proposed LCO is appropriate for the LTOP range.

Two operable PORVs provide redundancy for the purpose of satisfying single-failure criteria associated with LCO 3.4.13. In MODE 4, ACTION-a allows a 7-day AOT to restore an inoperable LTOP channel to operable status before other remedial actions would have to be taken. Seven days is considered acceptable based on the very low likelihood of an active failure occurring in the operable valve

St. Lucie Unit 1 L-94-153 Docket No. 50-335 Attachment 2 Proposed License Amendment Page 4 of 5 LTOP Re uirements for Power 0 crated Relief Valves GL 90-06 path during this period of time, and considering the transient mitigation capability of a single PORV. In MODES 5 or 6, ACTION-b provides added assurance of LTOP availability by reducing the AOT for a single inoperable channel to only 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> before other remedial actions are required. This more restrictive limit will improve LTOP availability under certain plant conditions when "the potential for an overpressure transient is highest". The proposed action statements do not deviate from the guidance in GL 90-06.

If the inoperable LTOP channel cannot be restored to OPERABLE status within the AOT specified in ACTION-a or ACTION-b, the RCS must be depressurized and vented within the next 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br />. The completion time to place the plant in this condition is reasonable, considering the total time from the point of entering the action statement (176 hours0.00204 days <br />0.0489 hours <br />2.910053e-4 weeks <br />6.6968e-5 months <br /> in MODE 4 or 32 hours3.703704e-4 days <br />0.00889 hours <br />5.291005e-5 weeks <br />1.2176e-5 months <br /> in MODES 5 or 6) and operator awareness of the administrative control requirements.

This AOT for a single inoperable PORV does not deviate from the guidance in GL 90-06.

If both PORVs become inoperable, completion of all remedial actions proposed ACTION-c requires within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />. This AOT is longer than the 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> recommended in GL 90-06. Since ACTION-c applies to MODE 4 as-well-as MODES 5 and 6, and since the specified interval represents the total time allowed to complete the action from the instant the applicable condition is discovered, FPL considers the GL 90-06 recommendation to be impracticable. Based on plant operating experience, an 8-hour period is not conducive to achieving an orderly and controlled cooldown-depressurization and would unnecessarily increase the risk associated with this type of transient. In addition, the proposed 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> interval is in agreement with other existing PSLl specifications which require cooldown and depressurization through the MODE 4 range. FPL believes the proposed action completion time satisfies the intent of GL 90-06.

The actions proposed for LCO 3.4.13 also provide for ongoing verification of the vent pathway (ACTION-d), special reporting requirements (ACTION-e), and exclusion from the provisions of TS 3.0.4 (ACTION-f). These action statements do not deviate from the guidance in GL 90-06 and the bases for the generic requirements are applicable to St. Lucie Unit 1.

The proposed SURVEILLANCE RE UIREMENTS do not deviate from those recommended in GL 90-06. The 72 hour8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> frequency for PORV ISOLATION VALVE OPEN position verification is reasonable, considering that remote position indication is available in the control room; and that alarm annunciation will occur if a PORV isolation valve is not

St. Lucie Unit 1 L-94-153 Docket No. 50-335 Attachment 2 Proposed License Amendment Page 5 of 5 LTOP Re uirements for Power 0 crated Relief Valves GL 90-06 fully open in the LTOP range. The CHANNEL FUNCTIONAL TEST will verify that the PORV lift setpoints are within the LCO limits on a periodic basis. The 31 day frequency is consistent with that of functional tests performed on other safety systems. Since PORV actuation could depressurize the RCS, valve operation is not required for this test. The CHANNEL CALIBRATION is the adjustment, as necessary, of the channel output to respond with the proper range and accuracy to known input signals and is performed pursuant to TS 1.4. The specified frequency of 18 months is consistent with other calibrations of this nature, and with PSL1 refueling outage schedules. The PORVs are tested pursuant to the Inservice Testing Program which is reviewed and approved by the NRC. Based on plant operating experience, FPL considers the proposed surveillance requirements to be acceptable.

In addition to the changes proposed for TS 3/4.4.13, existing St.

Lucie Unit 1 TS impose restrictions on the number of operable safety injection pumps (TS 3.5.3) and the conditions for starting RCPs (TS 3.4.14) when the RCS is in the LTOP range. These additional controls are designed to reduce the potential for the occurrence of overpressure events that could be caused by the addition of non-essential mass and energy to the RCS, and are consistent with the St. Lucie Unit 1 LTOP safety analysis.

conclusion Improved administrative restrictions involving the AOTs for PORVs, when in the Low Temperature RCS Overpressure Protection Range, are recommended by the NRC staff to increase LTOP availability and thereby enhance safety. For Combustion Engineering plants, guidance for such improvements is contained in GL 90-06, Enclosure B. Considering the plant specific design of St. Lucie Unit 1, the proposed changes to TS 3/4.4.13 are consistent with GL 90-06, Appendix B. In addition, TS have been implemented which limit mass and energy inputs to the RCS by restricting safety injection pump operability and placing restrictions on differential temperature for RCP restart. Therefore, FPL considers the proposed amendment to be acceptable.

- St. Lucie Unit 1 Docket No. 50-335 Proposed License Amendment DEZZZMINATION OF NO SIGNIFICANT HAZARDS CONSIDERATION

St. Lucie Unit 1 L-94-153 Docket No. 50-335 Attachment 3 Proposed License Amendment Page 1 of 2 LTOP Re uirements for Power 0 crated Relief Valves GL 90-06 DETERMINATION OF NO SIGNIFICANT HAZARDS CONSIDERATION Pursuant to 10CFR50.92, a determination may be made that a proposed license amendment involves no significant hazards consideration operation of the facility in accordance with the proposed amendment if would not: (1) involve a significant increase in the probability or consequences of an accident previously evaluated; or (2) create the possibility of a new or different kind of accident from any accident previously evaluated; or (3) involve a significant reduction in a margin of safety. Each standard is discussed as follows:

(1) Operation of the facility in accordance with the proposed amendment would not involve a significant increase in the probability or consequences of an accident previously evaluated.

The changes proposed for St. Lucie Unit 1 Technical Specifications (TS) 3/4.4.13 are similar to those recommended by the NRC staff via Generic Letter 90-06 for Low Temperature Overpressure Protection (LTOP) systems. On the basis of technical studies performed for Generic Issue 94, the staff concluded that LTOP system unavailability is a contributor to the risk associated with overpressure transients during the shutdown modes of plant operation. Revisions to the actions required and the time for completion of such actions, in the event that one or more Power Operated Relief Valves (PORV) become inoperable, provide more rigor than the existing specifications and are designed to increase LTOP system availability. The administrative restrictions do not change the results of existing analyses performed to evaluate postulated accidents but will improve the availability of systems designed to mitigate pressure transients that could occur within the LTOP range. Therefore, operation of the facility in accordance with the proposed amendment will not involve a significant increase in the probability or consequences of an accident previously evaluated.

(2) Operation of the facility in accordance with the proposed amendment would not create the possibility of a new or different kind of accident from any accident previously evaluated.

The proposed amendment will not change the physical plant or the modes of operation defined in the facility license. The changes do not involve the addition of new equipment or the modification of existing equipment, nor do they alter the design of St. Lucie plant

S g I

St. Lucie Unit 1 L-94-153 Docket No. 50-335 Attachment 3 Proposed License Amendment Page 2 of 2 LTOP Re irements for Power 0 crated Relief Valves GL 90-06 systems. Therefore, operation of the facility in accordance with the proposed amendment would not create the possibility of a new or different kind of accident from any accident previously evaluated.

(3) Operation of the facility in accordance with the proposed amendment would not involve a significant reduction in a margin of safety.

The proposed amendment provides additional administrative restrictions for the operation of LTOP equipment. The applicability of Limiting Conditions for Operation (LCO) involving the PORVs will be extended to include Operational MODE 6 when the head is on the reactor vessel, and the rigor of required actions and action completion times in the event that one or more PORVs become inoperable will be increased. Consequently, the risk of low temperature operations will be reduced and safety during the shutdown modes of operation will be enhanced. Therefore, operation of the facility in accordance with the proposed amendment would not involve a significant reduction in a margin of safety.

Based on the discussion presented above and on the supporting Evaluation of Proposed TS Changes, FPL has concluded that this proposed license amendment involves no significant hazards consideration.