ML17306A628
| ML17306A628 | |
| Person / Time | |
|---|---|
| Site: | Palo Verde  |
| Issue date: | 03/13/1992 |
| From: | Conway W ARIZONA PUBLIC SERVICE CO. (FORMERLY ARIZONA NUCLEAR |
| To: | Martin J NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION V) |
| References | |
| 161-04661-WFC-N, 161-4661-WFC-N, NUDOCS 9204080133 | |
| Download: ML17306A628 (20) | |
Text
ACCELERATED IQTIUBUTION DEMONSz&TION SYSTEM REGUDATORY ZNFORMATZON DZSTRZSUTZON SYSTEM (RZDS)
ACCESSION NBR:9204080133 DOC.DATE: 92/03/13 NOTARIZED:
NO DOCKET ¹ FACIL:STN-50-529 Palo Verde Nuclear Station, Unit 2, Arizona Publi 05000529 AUTH.NAME AUTHOR AFF1LIATION CONWAYFW.F.
Arizona Public Service Co. (formerly Arizona Nuclear Power RECIP.NAME RECIPIENT AFFILIATION MARTIN,J.B.
Region 5 (Post 820201)
SUBJECT:
Requests temporary waiver of compliance from TS limited conditions for operation '3.5.2, "ECCS," 3.6.2.1, "CS Sys,"
3.7.1.2, "AFS," 3.7.3 "Essential Cooling Water Sys,"
3.7.11, "SDCD" during 72 h diagnostic testing.
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05000529 RECIPIENT ID CODE/NAME PD5 PD THOMPSON,M INTERNAL: ACRS AEOD/DEIIB DEDRO NRR/DLPQ/LHFBPT NRR/DOEA/OEAB NRR/DST/DIR 8E2
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REC. i V"-D fcIP.C REGIO;"l Y A<>~ona Public Serv><e ComP>9g2 l"" l 8 All t~: 20 P.O, BOX 53999
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PHOENIX. ARIZONA85072-3993 WILLIAMF. CONWAY EXECUTIVEVICEPRESIDENT NUCLEAR Mr. John B. Martin Regional Administrator, Region V U. S. Nuclear Regulatory Commission 1450 Maria Lane, Suite 210 Walnut Creek, CA 94596-5368 161-04661-WFC/NLT March 13, 1992
Dear Mr. Martin:
Subject:
Palo Verde Nuclear Generating Station (PVNGS)
Vnit 2 Docket No. STN 50-529 Request for Temporary Waiver of Compliance from Technical Specifications File: 92-056-026 Arizona Public Service Company (APS) hereby requests a Temporary Waiver of Compliance from the following PVNGS Unit2 Technical Specifications'imiting Conditions for Operation (LCO): 3.5.2
- Emergency Core Cooling System (ECCS), 3.6.2.1-Containment Spray System (CSS), 3.7.1.2 - Auxiliary Feedwater System (AFS), 3.7.3-Essential Cooling Water System (ECWS), and 3.7.11
-. Shutdown Cooling System (SDCS).
The existing LCOs allow one train for each system to be inoperable for a maximum of 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />.
An additional 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> will be necessary to allow Unit 2 to perform diagnostic testing and corrective maintenance on the ECWS heat exchanger to repair tube leaks.
The ECWS is a required support system for the determination of operability of the aforementioned systems.
The Temporary Waiver of Compliance would allow Train A of each system to be inoperable for 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> beyond the currently allowed outage time.
The ECWS Train A also provides, cooling for the Essential Chilled Water System Train'A.
LCO 3.7.6 currently allows one essential chilled water train to be inoperable for a maximum of 7 days.
- Hence, a Temporary Waiver of Compliance is not required for LCO 3.7.6.
However, APS currently restricts operation with an inoperable train to no more than 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> as documented in Licensee Event Report 1-91-007-00.
APS is currently preparing a Technical Specification amendment request to change the 7-day action requirement for operability to 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> for the Essential Chilled Water LCO 3.7.6, consistent with the operability requirements of the ECCS, CSS, and AFS LCOs.
9204080133 920313 PDR ADOCK 05000529 P
161-04661-WFC/NLT March 13, 1992 Mr. John B. Martin U. S. Nuclear Regulatory Commission Temporary Waiver of Compliance Page 2 A Temporary Waiver of Compliance is being requested to prevent an unnecessary plant shutdown to Mode 5 and to provide up to 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> beyond the currently allowed outage time to perform diagnostic testing and corrective maintenance on the ECWS Train A heat exchanger.
APS. began working on, the ECWS at approximately 3:25 p.m. on March 12, 1992.
Therefore, it is requested that the NRC review and approve the enclosed Temporary Waiver, of Compliance prior to 3;25 p.m. on March'15, 1992, in order to allow work to extend beyond the currently allowed outage time.
Pursuant to 10 CFR 50.91(b)(1),'a copy of this request is being forwarded to the Arizona Radiation Regulatory Agency.
If you have any questions, please contact Michael E. Powell at (602) 340-4981; Sincerely, WFC/MEP/NLT/pmm Enclosure cc:
Document Control Desk C. M. Trammell D. H. Coe A. H. Gutterman W. A. Wright
tt
ENCLOSURE ARIZONAPUBLIC.SERVICE COMPANY REQUEST FOR TEMPORARY WAIVER OF COMPLIANCE.
PALO VERDE NUCLEAR GENERATING STATION UNIT 2 LIMITINGCONDITION,FOR OPERATION 3.5.2 3.6.2.1 3.7.1.2 3.7.3'.7.11 EMERGENCY CORE COOLING SYSTEM CONTAINMENTSPRAY SYSTEM AUXILIARYFEEDWATER SYSTEM ESSENTIAL COOLING WATER SYSTEM SHUTDOWN COOLING SYSTEM
161-04661-WFC/NLT March 13,'1992 REQUEST FOR TEMPORARY WAIVEROF COMPLIANCE LIMITINGCONDITION FOR OPERATION 3 5 2) 3 6 2 1 s 3 7.1 2~ 3 7 3s AND 3 7 1 1
, REQUIREMENTS FOR WHICH THE WAIVER IS REQUESTED Limitin Condition for 0 eration 3.5.2 Emer en Core Coolin S stem Limiting Condition for Operation (LCO) 3.5.2 specifies that at least 2 Emergency Core Cooling System (ECCS) subsystems shall be operable while in Modes 1, 2, and 3.
With one ECCS subsystem inoperable,'ction is required to restore at least two subsystems to operable status within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> or 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 hot shutdown within the following 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br />.
The operability of two separate and independent ECCS subsystems with the reactor coolant system (RCS) temperature greater than or equal to 350 'F ensures that sufficient emergency core cooling capability will be available in the event of a loss of coolant accident assuming loss of one subsystem through any single failure consideration.
Either subsystem operating in conjunction with the safety injection tanks is capable of supplying sufficient core cooling.
In addition, each ECCS subsystem provides long-term core cooling capability in the recirculation mode during the accident recovery period.
Arizona Public Service Company (APS) requests a Temporary Waiver of Compliance to the requirement for the restoration of ECCS Train A subsystems within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />.
APS proposes to extend this requirement 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> beyond the currently allowed outage time.
A Temporary Waiver of Compliance from LCO 3.5.2 action is required because support systems will be inoperable as a result of the workscope defined in this submittal.
'imitin Condition for 0 eration 3.6.2.1 Containment S ra S stem LCO 3.6.2.1 specifies that at least two independent Containment Spray Systems (CSS) shall be operable during Modes 1, 2, 3, and 4.
With one CSS inoperable, action is required to restore the inoperable spray system to operable status within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> or 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 />; restore the inoperable spray system to operable status within the next 48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br /> or be 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 />.
The operability of the CSS ensures that containment depressurization and cooling capability will be available in the event of-a loss of coolant accident.
The CSS and the containment cooling system are redundant to each other in providing post-accident cooling of the containment atmosphere.
The CSS also provides a mechanism for removing iodine from the containment atmosphere.
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161-04661-WFC/NLT March 13, 1992 APS requests a Temporary Waiver of Compliance to the requirement for the restoration of the CSS Train A within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />.. APS proposes to extend this requirement 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> beyond the currently allowed outage time.
A Temporary Waiver of Compliance is required from LCO 3.6.2.1 because support systems willbe inoperable as a result of the workscope defined in this submittal.
Limitin Condition for 0 eration 3.7.1.2 Auxilia Feedwater S stem LCO 3.7.1.2 specifies that at least three independent steam generator auxiliary feedwater pumps in the Auxiliary Feedwater System (AFS) and associated flow paths shall be operable during Modes 1, 2, 3, and 4. With one AFS pump inoperable, action is required to restore the required auxiliary feedwater pumps to operable status within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> or 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 hot shutdown within the following 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br />.
The operability of the AFS ensures that the RCS can be cooled down to less than 350 F
from normal operating conditions in the event of a total loss of offsite power.
APS requests a Temporary Waiver of Compliance to the requirement for the restoration of the AFS Train A Pump within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />.
APS proposes to extend this requirement 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> beyond the currently allowed outage time. A Temporary Waiver of Compliance is required from LCO 3.7.1.2 because support systems will be inoperable as a result of the workscope defined in this submittal.
Limitin Condition for 0 eration 3.7.3 Essential Coolin Water S stem LCO 3.7.3 specifies that at least two independent Essential Cooling Water System (ECWS) loops shall be operable while in.Modes 1', 2, 3, and 4. With only one essential cooling water loop operable, action'is required to restore at least two loops to operable status within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> or 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 />.
The operability of the ECWS ensures that sufficient cooling capacity is available for continued operation of safety-related equipment during normal and accident conditions.
The design of the system includes two separate, independent, redundant, closed loop, safety-related trains.
Either train of the ECWS is capable for supporting 100% of the cooling functions required for a safe reactor shutdown or following a loss of coolant accident.
The ECWS operates at a lower pressure than the Essential Spray Pond System (ESPS) as protection against leakage into the ESPS from the ECWS in case of tube leakage in the ECWS heat exchanger.
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161-04661-WFC/NLT March 13, 1992 APS requests a Temporary Waiver of Compliance to the requirement for the restoration of the ECWS Train Awithin 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />. APS proposes to extend this requirement 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> beyond the currently allowed outage time.
A Temporary Waiver of Compliance is required to allow for work to be performed on the ECWS Train A heat exchanger.
Limitin Condition for 0 eration 3.7.11 Shutdown Coolin S stem LCO 3.7.11 specifies that at least two independent Shutdown Cooling Systems (SDCS) shall be operable, with one operable low pressure safety injection pump, and an independent operable flow path capable of taking suction from the RCS hot leg and discharging coolant through the shutdown cooling heat exchanger and back to the RCS through the cold leg injection lines during Modes 1, 2, and 3. With one SDCS inoperable, action is required to restore the inoperable subsystem to operable status within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> or be in at least hot standby within 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> and be in at least hot shutdown 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 />.
4 The operability of two separate and independent shutdown cooling subsystems ensures that the capability of initiating shutdown cooling in the event of an accident exists even assuming the most limiting single failure. The shutdown cooling system is one means of providing long-term post-.accident reactor cooling.
One shutdown cooling subsystem, capable of supporting the entire heat load, would be initiated during the accident recovery period with the RCS temperature less than 350 'F.
APS requests a Temporary Waiver of Compliance to the requirement for the restoration of the SDCS Train A within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />.
APS proposes to extend this requirement for 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> beyond the currently allowed outage time. ATemporary Waiver of Compliance from LCO 3.7.11 is required since the ECWS is a support system for the SDCS heat exchanger.
NEED FOR PROMPT ACTION On March 4, 1992, the ECWS chloride and sulfate ions were at maximum concentrations of 6.6 and 18.3 parts per million (ppm), respectively.
These concentrations exceed the closed cooling water chemistry procedure acceptance criteria of'less than or equal to 5 ppm. Attempts to restore the out-of-specification parameters utilizing feed and bleed were unsuccessful.
Unit 2 Chemistry was informed that the ECWS expansion tank level had increased when running the pumps on the Essential Spray Pond System (ESPS) without the ECWS pumps running.
Though the heat exchanger water quality was well within Updated Final Safety Analysis Report Table 9.2-5
.specifications, there had been an increase in chlorides (to approximately 4-6 ppm) and sulfates (to approximately 17 ppm). These anions were believed to have been introduced into the ECWS from the ESPS due to heat exchanger tube leaks.
The heat exchanger is of the shell and tube type. The tube side is furnished 3 of'6
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161-04661-WFC/NLT March 13, 1992 with cooling water from the ESPS.
The shell side carries the ECWS cooling water. This closed-loop, shell-side. water is initially supplied with demineralized water from the demineralized water system. The effect of sulfates and chlorides on system corrosion will increase as contaminant levels increase, although the ECWS is normally at ambient temperature which will minimize the potential corrosive effects.
=
Based on the closed cooling water chemistry analysis and expansion tank level increases, APS suspected that the ECWS Train A heat exchanger had tube leaks.
This was confirmed on March 13, 1992.
A Temporary Waiver.of Compliance is being requested:
to prevent an unnecessary plant shutdown to Mode 5 and to provide up to 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />,
'eyond the currently allowed outage time to perform diagnostic testing and corrective maintenance on the ECWS Train A heat exchanger.
COMPENSATORY MEASURES Unit 2 Operations will maintain operability of the Train A ESPS and Emergency Diesel Generator (EDG) while in these LCO actions.
Additionally, Unit 2 Operations willensure that Train B systems, subsystems, and components will be verified and maintained fully operable while in these LCO action statements, in accordance with Technical Specifications and Palo Verde Nuclear Generating Station (PVNGS) procedures, to facilitate safe operation and shutdown of Unit 2.
APS will enter Technical Specification LCO 3.7.6, ACTIONS a and b for the Essential Chilled Water System.
LCO ACTION b requires verification that the Normal Heating, Ventilation, and Air-conditioning System (HVAC) is providing space cooling to the vital power distribution rooms that depend on the inoperable Essential Chilled Water System
- for space cooling.
Upon positive verification of the Normal HVAC cooling, no further cascading of the Unit 2 Technical Specifications is required (i.e., the 2-hour LCO 3.8.2.1
.for loss of direct current sources is not applicable with the verification of'he Normal HVAC).
JUSTIFICATION FOR AND DURATION OF THE REQUEST The extension of the LCO for 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> beyond the allowed outage time, for one inoperable train, of the ECWS and resulting systems, will provide the opportunity to perform diagnostic testing and corrective maintenance on Unit 2 ECWS Train A heat exchanger.
Failure to grant relief for the additional 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> may result in an unnecessary plant shutdown and a consequent plant transient.
Work on the ECWS Train A heat exchanger will require entering the 72-hour action statements.
Work will entail clearing the system for work, draining the system, visual inspection, and eddy current inspection.
Visual inspection may be performed using a camera and/or a boroscope.
Eddy current testing will be performed on suspect tubes, as required.
Results of the eddy current examination will be evaluated and the
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161-04661-WFC/NLT March 13, 1992
, determination of additional eddy current examinations will be determined.
In the event additional testing is required, the ECWS may not be returned to service in the time required by LCO 3.7.3. Consequently, the request for a Temporary Waiver of Compliance frorri LCO 3.5.2, 3.6.2.1, 3.7.1.2, 3.7.3 and 3.7.11 to allow Train A systems to be
, inoperable for 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> beyond the allowed outage time, has been evaluated and it has been determined that this request will not impact public health and safety.
A Probabilistic Risk Analysis was performed to determine the impact on plant risk associated with a one-time extension of the LCOs for 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> beyond the allowed outage time. The results are applicable under the following conditions:
(1) the tube leak is small such that the ECWS can be considered operable until it is removed from service for repairs; (2) all opposite train components remain operable through the duration of the action statement; and (3) the Train A ESPS cooling to the EDG would be available through the duration of the action statement.
The additional 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> allowed by the Temporary Waiver of Compliance will result in an increase in core damage probability from 2.5E-6 to 5.0E-6 (an increase of 2.5E-6 relative to the currently allowed outage time).
EVALUATIONOF THE SAFETY SIGNIFICANCE AND BASIS FOR NO SIGNIFICANT HAZARDS CONSIDERATION The required corrective action can be performed successfully at power on Train A.
During normal plant operation, the ECWS, ECCS, CSS, AFS, SDCS, and Essential Chilled Water System are not operating.
The redundant features of these systems allow testing of 1 train without violation of Technical Specifications. When the action statement for LCO 3.7.3 is entered, the action statements for the aforementioned systems must be entered since these systems can perform their functions only if all necessary support systems are capable of performing their related 'support functions.
When a support system is determined to be inoperable, all systems for which that support system is required for system operability are declared inoperable and the LCOs for those systems are entered.
The Temporary Waiver of Compliance only impacts the time allowed for Train A to be inoperable and does not change the equipment which is allowed to be inoperable.
Therefore, the consequences of a previously evaluated accident remain unchanged.
Increasing the allowed out-of-service time of the aforementioned LCOs for an additional 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> on a one-time only basis for the purpose of performing diagnostic testing and corrective maintenance is the safest course of action other than placing the unit in cold shutdown.
The safety function of'Train A can be performed by the 100% redundant Train B.
The possibility of a new or different kind of accident from any accident previously evaluated willnot be created by the increase in time allowed for an inoperable train.
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161-04661-WFC/NLT March 13, 1992 Extension of the 72-hour limitwould not involve a significant reduction in the margin of safety because there are no new or common failure modes being created by the extension.
The performance of the associated safety systems*will not be degraded by the extended out-of-service time.
ENVIRONMENTALIMPACT CONSIDERATION DETERMINATION The proposed Temporary Waiver of Compliance request does not involve an unreviewed environmental question because operation of PVNGS Unit 2 with-the LCO extensions would not:
A.
Result in a significant increase in any adverse environmental impact previously evaluated in the Final Environmental Statement as modified by the Staff's testimony to the Atomic Safety and Licensing Board; or B. 'esult in a significant change in effluent or power levels; or C.
-Result in matters not previously reviewed in the licensing basis for PVNGS which may have a significant environmental impact.
As discussed
- above, no significant reduction in the margin of safety and no new
. accidents are introduced by this Temporary Waiver of Compliance.
This Temporary Waiver of Compliance does not significantly affect effluent or power levels, and has no environmental impact.
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Ir,