IR 05000361/1998018
| ML20207E674 | |
| Person / Time | |
|---|---|
| Site: | San Onofre  |
| Issue date: | 06/02/1999 |
| From: | NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I) |
| To: | |
| Shared Package | |
| ML20207E658 | List: |
| References | |
| 50-361-98-18, 50-362-98-18, NUDOCS 9906070102 | |
| Download: ML20207E674 (10) | |
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EXECUTIVE SUMMARY San Onofre Nuclear Generating Station, Units 2 and 3 NRC Inspection Report 50-361/98-18; 50-362/98-18 Operations
Postmaintenance testing, as prescribed by operations work control, for scheduled emergency chiller maintenance was not adequate because work that affected the start circuit for the chiller was not tested. This deficiency was identified as a noncited violation of 10 CFR Part 50, Appendix B, Criterion V, consistent with Section Vll.B.1 of the Enforcement Policy. This deficiency contributed to inoperability of Chiller E335 for 22 days in September 1998 (Section O8.1.b.2).
A faulty temperature control unit, an incorrectly set electrical demand switch, and noncondensable gases rendered Chiller E335 inadvertently inoperable for 20 consecutive days in August 1998. Similarly, a miswired low chilled water temperature cutout switch or a combination of noncondensable gases, oil in the refrigerant, and an electrical demand setting of 80 percent rendered Chiller E335 inoperable for 22 consecutive days in September 1998. The time periods for these inoperabilities exceeded the Technical Specifications Limiting Condition for Operation 3.7.10 allowed outage time and was identified as an apparent violation (Section 08.1.b.3).
- The emergency chilled water system operating procedure specified that the electrical demand be limited to 80 percent, which reduced chiller capacity below that assumed in design bases document. The failure to translate the design basis requirement for emergency chiller capacity in the operations procedures for setting electrical demand contributed to emergency Chiller E 335 inoperability during August and September 1998. This failure was identified as a noncited violation of 10 CFR Part 50, Appendix B, Criterion ill, ' Design Control." However, this deficiency alone did not render the emergency chiller inoperable. This nonrepetitive, licensee-identified and corrected violation is being treated as a noncited violation consistent with Section Vil.B.1 of the NRC Enforcement Policy (Section 08.1.b.5).
- Operators demonstrated poor awareness of the effects of compressor oil pump 1 operation on a standby emergency chiller. Operators operated the oil pump with the compressor in standby for greater than the time allowed by procedure in attempts to J lower a high oil level. The inspectors identified this as a failure to follow a procedure l required by Technical Specification 5.5.1.1.a. Since the licensee implemented appropriate corrective actions, no response was required (Section 08.2).
Maintenance ,
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- Maintenance personnel demonstrated poor control of lifted leads and of emergency chiller switch settings. An instrumentation and control (l&C) technician failed to i properly reconnect wires to an emergency chiller low temperature cutout switch, !
rendering the chiller inoperable. The failure to follow procedure was identified as a noncited violation of Technical Specification 5.5.1.1.a, consistent with Section Vll.B.1 of the Enforcement Policy. During the same maintenance activity, the chiller was left with an improper thermostat setting and the sequence for the low chilled water and low 9906070102 990602 PDR ADOCK 05000361 O PDR v
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Report Details
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Summary of Plant Status -
Units 2 and 3 operated at essentially 100 percent power during this inspection perio ,
l. Operations 08, Miscellaneous Operations issues (92700)
08.1 (Closed) Licensee Event Reoorts 50-361: 362/98-020-00 and 98-021-00: emergency -
chilled water (ECW) inoperable because of faulty temperature control unit and ECW
' inoperable because of an incorrectly wired switc ; Inspection Scope The inspectors reviewed the circumstances conceming two periods of inadvertent j inoperability of Units 2 and 3 Train B ECW, as pertains to operations. The inspectors reviewed Procedure SO23-1-3.1, " Emergency Chilled Water System Operation,"
Temporary Change Notice 10-2, and Design Bases Document SO23-800, " Auxiliary
. Building Chilled Water System," Revisions 0 and 2. The inspectors reviewed portions of Work Action Request (WAR) C-9802021 and a work schedule for implementing this 1 WAR prepared on August 13,1998. The inspectors reviewed portions of the chiller vendor manual, Technical Manual SO23-410-7-164-2, " Operating instructions for Carrier Centrifugal Refrigeration Machines," Revision 2. The inspectors also interviewed operators and operations management personne > . Observations and Findinas
! Seauence of Events
. As described in the licensee event reports, Chiller E335, Train B emergency chiller (common to both units), was inadvertently inoperable for 20 continuous days in August 1998 and for 22 continuous days in September 199 .
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- On August 6, Chiller E335 was operated to suppor1 a monthly control room emergency air cleanup system surveillance. Operators observed that the I j
~ chilled water temperature leaving the chiller decreased to approximately 51 *F; however, the normal chilled water outlet temperature was 43*F. Operators
' considered Chiller E335 operable; however, they generated an action request (AR) to have engineering assess operabilit * On August 26, operators removed Chiller E335 from service for scheduled maintenance and declared the emergency chiller inoperabl * On August 28, l&C technicians replaced the temperature control uni ;
Operators performed a postmaintenance test that demonstrated satisfactory
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performance and declared Chiller E335 operabl i
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On August 31, operators removed Chiller E335 from service for scheduled maintenanc = On September 3, an l&C technician disconnected the leads from a low temperature chilled water cutout switch, in order to perform a dynamic calibration of the switch setpoint. During the dynamic calibration, the I&C technician stopped the calibration after hearing the emergency chiller make a rumbling nois
On September 4, operators declared Chiller E335 operable after verifying that the chiller continued to operate satisfactorily; however, the operators did not start Chiller E33 =
On September 25, Chiller E335 failed to start when operators attempted to perform a monthly control room emergency air cleanup system surveillanc I Subsequently, the licensee determined that the l&C technician had incorrectly wired the low chilled water temperature cutout switch for Chiller E335, and the
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postmaintenance test failed to detect the error. This error rendered Chiller E335 inoperable from September 4 to 2 * During troubleshooting on and after September 25, the licensee determined that noncondensable gases present in Chiller E335 from August 6 to September 25 degraded the capability of the chiller condenser. In October 1998, as part of the operability review, the licensee determined that Chiller E335 had been degraded from August 6-26, because of several factors: (1) a faulty temperature control unit, (2) an incorrectly set electrical demand switch in the control circuit, and (3) the presence of noncondensable gases in the refrigerant. The licensee determined that these factors combined with a 51 *F chilled water outlet temperature rendered Chiller E335 inoperable under design bases load condition b.2 Postmaintenance Testina '
Chiller E335 was removed from senrice for scheduled maintenance on August 3 WAR C-9802021 and a work schedule prepared on August 13 directed that Chiller E335 be operated in accordance with Procedure SO23-1-3.1 to verify operability following the maintenance. Concurrent with the operability test, a dynamic calibration of low chilled water and low refrigerant temperature cutout switches was scheduled to be performed.'
The design chilled water outlet temperature for Chiller E335 is 43*F. The low chilled water temperature cutout switch has a nominal setpoint of 38'F. The switch contacts are normally closed above 38'F and normally open below 38'F. When the switch -
contacts open, the chiller compressor trips and the chiller shuts down. The switch contacts were installed in the start circuit for the chiller, such that the chiller would not start manually or automatically with the contacts open. During the dynamic calibration, an l&C technician disconnected the wires from the low chilled water temperature cutout switch and installed a jumper to disable the switch cutout from tripping the chille Because of personnel error, an 1&C technician had reterminated the switch wires incorrectly. In addition, although the dynamic calibration affected contacts in the chiller start circuit, the postmaintenance test did not test the capability of the start circuit to
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-3-start the emergency chiller. Failing to provide instructions for postmaintenance testing appropriate to the circumstances was a violation of 10 CFR Part 50, Appendix B, Criterion V, " Instructions, Procedures, and Drawings."
The licensee initiated the following corrective actions to prevent recurrence: (1) add a postmaintenance test requirement to start the chiller after a dynamic calibration and (2) assess the adequacy of the retest program and evaluate the committee that met to approve retest requirements. This nonrepetitive, licensee-identified and corrected violation is being treated as a noncited violation, consistent with Section Vll.B.1 of the NRC Enforcement Policy (50-361; 362/98018-01). Technical Specifications The licensee determined that Chiller E335 was inadvertently inoperable from August 6 to 26, and from September 3 to 25 (periods of 20 d ws and 22 days, respectively).
Unit 3 was in Mode 1 operation for this entire period. Unit 2 was in Mode 1 for 22 consecutive days in August and the first 15 of the 22 co.nsecutive days in Septembe Technical Specification Limiting Condition for Operation 3.7.10 directs that, with o train of ECW inoperable, each unit shall restore the train to operability in 7 days. If the train is not restored by the end of the 7 days, then the limiting condition for operation requires operators to place the unit in Mode 3 in 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> and be in Mode 5 in 36 hour4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br /> Because operators were not aware that Train B ECW was inoperable, these completion times were not complied with, which resulted in an apparent violation of Technical Specification Limiting Condition for Operation 3.7.10 (50-361; 362/98018-02).
The inspectors verified that Train A ECW remained operable throughout the 2-month period. Operations had declared Train A ECW inoperable from September 15 to 16, because of an air leak on the expansion tank, which caused the tank to fill with water and pressure to decrease. Also, the operators had declared the Train A Emergency Diesel Generator (EDG) 2G002 (the power source Chiller E336, Train A emergency chiller) inoperable on September 15 because the fuel transfer pump was returned to service without the required inservice test. As discussed below, the Train A chiller and the Train A EDG were shown operable throughout the period the Train B emergency chiller was inoperabl b.4 Train A Operability Assessments For the occurrence with the Train A expansion tank full of water, the expansion tank pressure decreased to approximately 30 psig, which was the hydrostatic pressure that I resulted from 70 feet of water in the chilled water piping above the expansion tank. The chilled water pump required approximately 4 psig suction pressure to avoid cavitation from a loss of net positive suction head. If the chiller would have been started and I operated, the pump suction could have decreased to approximately 15 psig (the I hydrostatic pressure only - assuming a vacuum at the top of the water column). This l 15 psig (hydrostatic pressure) exceeded the 4 psig required suction pressure. The I chilled water pump would have provided approximately 69 psig discharge pressure I (nominal pump delta-p is 54 psi) given an expansion tank at 15 psig. The 69 psig i discharge pressure would have been sufficient to pump chilled water throughout the I chilled water piping. The licensee demonstrated, via analysis in AR 980900850, that i some gas pockets and separation of water from gas may have occurred on the chilled ;
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-4-water pump suction side high points; however, the licensee determined that the chilled I water flow would have been sufficient to collapse or mix these gas pockets, such that I flow through all sections of piping would be maintained. Consequently, the inspectors i found that the Train A emergency chilled water system could perform its intended I function under these condition I A second occurrence resulted with Train A chilled water powered by EDG 2G002, which was declared inoperable because both fuel transfer pumps were inoperable. Each EDG has two fuel transfer pumps that transfer fuel from the EDG fuel storage tank to the day tank. On September 15, one EDG fuel transfer pump (Pump 2P096) was removed from service for maintenance. Subsequently, this fuel transfer pump was declared operable, and the second EDG fuel transfer pump (Pump 2P093) was removed from service for maintenance. While the second fuel transfer pump was removed from service, engineers decided that the retest for the first fuel transfer pump should have included an inservice test because the pump had been decoupled from its motor during the maintenance. Consequently, for a period of time, operators declared both fuel transfer pumps inoperable. The first fuel transfer pump passed an inservice test that was subsequently administered. Since one fuel transfer pump had remained available, the inspectors found that the fuel transfer system for EDG 2G002 could perform its intended functio b.5 Electrical Demand Train B Chiller E335 had an electrical demand setting on the control module that could limit the amount of current that the chiller compressor motor would draw. Prior to September 25, Procedure SO23-1-3.1 directed operators, during prestart checks of the chiller, to set electrical demand to 80 percent. This electrical demand setting of 80 percent limited the Chiller E335 to 85 percent of nameplate capacity and contributed to Chiller E335 inoperability during August and September 1998 because this limited the capacity of the chille Setting the electrical demand to 80 percent was not referenced in any design documents, and the licensee could not present a bases for this setting. The vendor manual stated that the variable electrical demand limited chiller capacity during colder periods, so that the chiller would not unnecessarily consume electrical power. The design bases for Chiller E335, as stated in Design Bases Document SO23-800, indicated that the chiller would provide 4.8 x 108BTU / hour cooling. However, Procedure SO23-1-3.1 limited the chiller capacity to approximately 4.1 x 10 8BTU / hour ,
when the electrical demand was set at 80 percent. While less than the design basis j
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specification, the licensee stated that the limited chiller capacity was still sufficient to cool design basis heat loads if the chiller was functioning properly.10 CFR Part 50, ,
Appendix B, Criterion lil, " Design Control," states, in part, that the design bases for
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components shall be correctly translated into procedures. The failure to translate design basis requirements for chiller capacity into operations procedures for setting electrical demand is a violation of NRC requirements. Upon discovery of this condition, the licensee revised Procedure SO23-1-3.1 to require setting electrical demand at 100 percent. The inspectors found this corrective action satisfactory. This l nonrepetitive, licensee-identified and corrected violation is being treated as a noncited violation, consistent with Section Vll.B.1 of the NRC Enforcement Policy (50-361;362/98018-03).
5 Also, on September 30, operators had started the Train A Chiller E336 with the electrical demand set at 80 percent; however, the motor current slightly exceeded the nameplate value, indicating that electrical demand switch was not properly limiting current. The licensee calibrated the electrical demand for Train A Chiller E336 and verified that the electrical demand for Train B Chiller E335 met specifications. Although the vendor manual did not have a recommended calibration interval for operational settings, such as electrical demand, the licensee had calibrated electrical demand on 6-year interval From August 28 to 31, the inspectors determined that HVAC technicians had set I electrical demand at 100 percent for Chiller E335 after replacing the temperature control unit. Although this setting met the design bases and maintenance procedure requirements, the inspectors noted that the setting conflicted with the requirements specified in Procedure S023-1-3.1. Consequently, the inspectors found that control of chiller electrical demand was poor and contributed to the noncited violation of design control since the maintenance and operations procedures conflicte c. Conclusions Postmaintenance testing, as prescribed by operations work control, for scheduled emergency chiller maintenance was not adequate because work that affected the start circuit for the chiller was not tested. This deficiency was identified as a nancited violation of 10 CFR Part 50, Appendix B, Criterion V, consistent with Section Vll.B.1 of the Enforcement Policy. This deficiency contributed to inoperability of Chiller E335 for 22 days in September 199 A faulty temperature control unit, an incorrectly set electrical demand switch, and noncondensable gases rendered Chiller E335 inoperable for 20 consecutive days in August 1998. Similarly, a miswired low chilled water temperature cutout switch or a combination of noncondensable gases, oil in the refrigerant, and an electrical demand setting of 80 percent rendered Chiller E335 inoperable for 22 consecutive days in September 1998. The time periods for these inoperabilities exceeded the Technical Specifications Limiting Condition for Operation 3.7.10 allowed outage time and was identified as an apparent violatio The emergency chilled water system operating procedure specified that the electrical demand be limited to 80 percent, which reduced chiller capacity below that assumed in design bases document. The failure to translate the design basis requirement for emergency chiller capacity in the operations procedures for setting electrical demand contributed to emergency Chiller E 335 in operability during August and September 1998 was identified as a noncited violation of 10 CFR Part 50, Appendix B, Criterion 111, " Design Control." However, this deficiency alone did not render the emergency chiller inoperable. This nonrepetitive, licensee-identified and corrected violation is being treated as a noncited violation consistent with Section Vll.B.1 of the NRC Enforcement Polic l
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11. Maintenance M8 Miscellaneous Maintenance issues (92700)
M8.1 Maintenance of Emeraency Chiller E335 Inspection Scope The inspectors reviewed the circumstances concerning two periods of inadvertent inoperability of Units 2 and 3 Train B ECW, as pertains to maintenance. The inspectors reviewed Licensee Event Reports 50-361; 362/98-020-00 and 98-021-00. The inspectors reviewed Procedure S023-11-8.25 and interviewed l&C technicians, as well as maintenance supervisors. The inspectors reviewed portions of Procedure S0123-11-15.3," Temporary System Alteration and Restoration Form,"
Revision 7, and portions of Technical Manual SO23-410-7-164-2, Revision Observations and Findinas .ifted Lead Control On September 3,1998, an l&C technician disconnected the leads from the Chiller E335 low chilled water temperature cutout switch, as instructed by Procedure SO23-II-8.25, in order to perform a dynamic calibration of the switch setpoint (nominally 38*F) and reset point (nominally 48'F). As directed by Procedure S023-11-8.25, a day shift l&C technician jumpered out the low refrigerant temperature and low chilled water temperature cutouts and disconnected the wires from both of these switches. A swing shift l&C technician continued with the calibration by lowering thermostat temperature, until the refrigerant switch actuated. When the thermostat was lowered further, to provide approximately 38'F chilled water temperature (nominal switch setpoint), the chiller began to make loud, rumbling noises. In addition, cooler pressure lowered to about 30 psi, the minimum cooler pressure allowed by Procedure S023-11-8.25. The l&C technician decided to back out of the calibration and restore the chille Procedure SO23-II-8.25, step 6.3.3, directed that the wires removed from the low chilled water temperature cutout switch be reconnected. The low chi'lled water temperature switch contact is normally closed above switch setpoint (chilled water temperature above 38'F) to allow operation. The low chilled water temperature switch contact opens to either trip the chiller and prevent chiller automatic and manual start, when the switch is below setpoint (chilled water temperature below 38'F). The switch has three connection I points for the two wires. The technician reconnected the wires to the connection point screws that corresponded to a closed contact by using a voltmeter to establish these points. The technician then reported to operations work control that he was unable to complete the dynamic calibratio The licensee determined that, on September 25, when Chiller E335 failed to start, the l&C technician had connected the wires to the wrong screws. The low temperature cutout switch had changed state, such that the I&C technician had unknowingly
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x Observations and Findinas . Operability Assessment
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' On August 6,1998, operators started Chiller E335 to support a control room emergency I
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air cleanup system surveillance.' Operators generated AR 980800326 because _
. Chiller E335 was maintaining 51 *F outlet chilled water temperature, instead of the -
' design 43*F. The cognizant engineer performed an operability assessment, approved
- by an acting supervisor, which concluded the chiller remained operable. The engineer .
concluded in the operability assessment that 51 *F chilled water outlet temperature was -
acceptable to cool the actual loads on the chiller. _ However, the operability assessment
' did not address increased loading on the chiller that would result from a design basis
, , accident condition (one unit in a loss of coolant accident and the other shutting down).
The licensee subsequently determined that noncondensable gases in the refrigerant
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and problems _with the temperature control unit had rendered the chiller inoperable on August 6. The inadvertent inoperability remained until August 26, when Chiller E335 was declared inoperable for scheduled maintenance, which included replacing the faulty temperature control uni Procedure SO123-XX-1, step 6.6.2.2.5, states, in part, that to accept a condition as-is and justify that the configuration continues to satisfy design requirements, a
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nonconformance report is required. The operability assessment was not accomplished in accordance with Procedure SC123-XX-1. Utilization of a nonconformance report, in
. principle, would have caused increased engineering attention to the design of the chiller and the effect of the degradation on the chiller. The failure to promptly identify and correct a condition adverse to quality is a violation of 10 CFR Part 50, Appendix B,
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Criterion XVI, ' Corrective Action." The licensee had implemented corrective actions that included: (1) developing a station technical reading assignment, (2) counseling personnel involved, and (3) considering enhancing standard questions used during operability assessments. This nonrepetitive, licensee-identified and corrected violation is being treated as a noncited violation, consistent with Section Vll.B.1 of the NRC Enforcement Policy (50-361; 362/98018-06).
b.2 l Vendor Information The inspectors noted that the chiller vendor manual recommended that a set of ]
operating logs be taken when operating the chiller in order to be able to detect i degradation in chiller performance. The recommended logs included chilled water ,
temperature entering and leaving the chiller, refrigerant temperatures and pressures, and component cooling water temperatures entering and leaving the chiller. The inspectors determined that Procedure SO23-1-3.1 did not require operators to monitor any of these parameters in order to analyze for performance degradation, in addition, the chiller vendor manual provided saturation tables for refrigerant
. temperature and pressure to be used in order to detect noncondensable gases in the refrigerant. A refrigerant temperature 2*F below the saturation temperature for any given pressure was indicative of noncondensable gases. Licensee personnel had not !
utilized this information on September 3, nor during other past attempts at dynamic
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calibration, when refrigerant pressure (limited to 30 psi) prevented completing the j
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dynamic calibration. This information was not used until September 25 when a vendor i
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o-11-representative suggested that noncondensable gases were present in the refrigeran Noncondensable gases had degraded chiller performance for at least 2 months prior to September 25. The inspectors concluded that station technical engineers demonstrated weak performance monitoring of the chillers, in that personnel failed to make full uso of the information available in the chiller vendor manua . Conclusions Engineering demonstrated poor assessment of equipment operability and understanding of information contained in a vendor manual. A flawed operability assessment when an i emergency chiller could not achieve design cooling resulted in an inadvertent l inoperability of the chiller for approximately 20 days during August 1998. The failure of ,
engineers to take appropriate actions to demonstrate operability of the Train B j emergency chiller, as specified by the corrective action program, was identified as a 1 noncited violation of 10 CFR Part 50, Appendix B, Criterion XVI, " Corrective Action," '
consistent with Section Vll.B.1 of the NRC Enforcement Policy. Had the licensee implemented the vendor manual recommended performance monitoring of the chillers, the buildup of noncondensable gases in the refrigerant during August and September 1998 would have been detecte E8.2 Effect of Noncondensable Gases on Chiller Performance a. Inspection Scope The inspectors reviewed data of Chiller E335 performance to assess operabilit b. Observations and Findinas Licensee Event Reports 50-361; 362/98-020-00 and 98-021-00 described that the chillers have a 35 percent capacity margin and that the noncondensable gases degraded the chiller performance by 11 percent. The capacity margin was based on calculations of design load (one unit in a loss of coolant accident and one shutting down). The loads on the chiller were divided by the chiller capacity to determine the excess capacity the chillers possessed. The licensee based the 11 percent degradation on comparisons of chiller performance when equipment status, as wel: as the presence of noncondensable gases, was know The inspectors identified that chilled water exit temperature (as a function of time) data recorded for September 25,1998, and chiller operation with control room emergency air I cleanup system loading contradicted either or both the 35 percent capacity margin or the 11 percent degradation resulting from the noncondensable gases. The inspectors -
noted that, in principle, for the chiller operation on September 25, the chiller should have had a 9 percent excess capacity for design loading. Specifically, operators had set the i current limiter to 80 percent, which provided 85 percent available capacity. Since j noncondensable gases were present, this 85 percent capacity should have been J reduced to no lower than 74 percent chiller output (based upon the 11 percent j l
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- Southern California Edison C JN-21999 E-Mail report to T. Frye (TJF)
E-Mail report to D. Lange (DJL)
E-Mail report to NRR Event Tracking System (IPAS)
E-Mail report to Document Control Desk (DOCDESK)
E-Mail report to Richard Correia (RPC)
E-Mail report to Frank Talbot (FXT)
bec to DCD (IE14)
bec distrib. by RIV:
Regional Administrator Resident inspector DRP Director' DRS-PSB DRS Director - MIS System Branch Chief (DRP/E) RIV File Senior Project inspector (DRP/E)
Branch Chief (DRP/TSS)
G. F. Sanborn, EO W. L. Brown, RC-J. Lieberman, OE, MS: 7-H5
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OE: EA File, MS: 7-H5 DOCUMENT NAME: R:\_SO23\S0818AK.JJR To receive copy of document. Indicate in box: "C" = Copy without enclosures "E" = Copy with enclosures "N" = No copy RIV:RI:DRP/E SRI C:DRP/E l JJRussell JASloan LJSmith LTI, 6/1/99 (T) 6/1/99 (T) 6/7., /99 OFFICIAL RECORD COPY i
SodlHrRN CALHoRNIA
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- EDISON o-'<h' ' " -
Vice President An EDISO4 INTEK\ATIONAL* Company
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February 16,1999 'x N/ '-
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U. S. Nuclear Regulatory Commission /
Attention: Document Control Desk /
Washington, D.C. 20555 Subject: Docket Nos. 50-361 and 50-362 Response to An Apparent Violation in Inspection Report No. 50-361; 362/98-18 (Violation 98018-02; EA 98-563)
San Onofre Nuclear Generating Station Units 2 and 3 References: 1) Letter dated January 15,1999, from Ken E. Brockman (NRC) to Harold Ray (SCE), Subject: NRC Inspection Report 50-361/98-18; 50-362/98-18 and Notice of Violatio ) Letter dated October 26,1998, from R. W. Krieger (SCE) to Document Control Desk (NRC), Subject: Docket Nos. 50-361 and 50-362,30-Day Report, Licensee Event Reports No. 1998-020 and 1998-021, San Onofre Nuclear Generating Station, Unit 2 and Gentlemen:
Reference I transmitted Nuclear Regulatory Commission (NRC) Inspection Report 50-361/98-18 and 50-362/98-18 regarding a specialinspection conducted November 9 through December 18, 1998, at the San Onofre Nuclear Generating Station, Units 2 and 3. The Inspection Report described an apparent violation related to inoperabilities of the Train B, Emergency Chiller ME 335 (Item 98018-02; EA 98-563). On January 21,1999, Mr. A. E. Scherer of Southern California Edison (SCE) contacted Ms. L. J. Smith of the NRC and declined the opportunity to have a predecisional enforcement conference and indicated that SCE would provide a written response to the apparent violation in compliance with Reference 1. The Enclosure to this letter provides that response under oath or affirmatio P.O.Bos128 San Clemente. CA 92674 O'28
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Document Control Desk -2- February 16,1999 As discussed in the January 21,1999 telephone conversation, there are no material issues in the Inspection Report in dispute, however, SCE would, nevertheless, like to correct / clarify a few items contained in Reference 1. These corrections / clarifications are provided as an attachment to this lette 'l-If there are any further questions, please contact m
Sincerely, s
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Enclosure Attachment ec: E. W. Merschoff, Regional Administrator, NRC Region IV J. A. Sloan, NRC Senior Resident Inspector, San Onofre Units 2 and 3 J. W. Clifford, NRR Project Manager, San Onofre (Jidts 2 and 3 J. Lieberman, Director, Office of Enforcement, NRC
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State of California -
County of San Diego i
Dwight E. Nunn, being duly sworn, hereby deposes and says that he is Vice President of Southern California Edison, San Onofre Nuclear Generating Station; that as such he is duly authorized to sign and file with the Nuclear Regulatory Commission the attached information concerning the response to an Apparent Violation; that he is familiar with the content thereof; and that the matters set forth therein are true and correct to the best of his knowledge, information, and belie f
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Vice President k
Subscribed and sworn before me this Ilo dayof $d .199 ........ ,
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l ENCLOSURE RESPONSE TO AN APPARENT VIOLATION q Inspection Report 98-18, transmitted via Ken E. Brockman's letter dated January 15,1999, Reference 1, states in part:
"The licensee determined that Chiller E335 was inadvertently inoperable from August 6 to 26, and from September 3 [ sic - 4] to 25 (periods of 20 days and 22 days, respectively).
Unit 3 was in Mode 1 operation for this entire period. Unit 2 was in Mode 1 for 22 consecutive days in August and the first 15 of the 22 consecutive days in Septembe ,
Technical Specification Limiting Condition for Operation 3.7.10 directs that, with one l train of ECW inoperable, each unit shall restore the train to operability in 7 days. If the train is not restored by the end of the 7 days, then the limiting condition for operation requires operators to place the unit in Mode 3 in 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> and be in Mode 5 in 36 hour4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br /> Because operators were not aware that Train B ECW was inoperable, these completion times were not complied with, which resulted in an apparent violation of Technical Specification Limiting Condition for Operation 3.7.10 (50-361; 362/98018-02)." l The specific sequence of events related to the chiller inoperabilities is detailed in Inspection Report 98-18, Section 08.1.b.1, as well as Licensee Event Reports (LER) 1998-020 and 1998-021 (Reference 2). Reason for the Apparent Violation As described in LER 1998-020, the reason for the Technical Specification violation during the 20 continuous days in the month of August 1998 was an inadequate Operability Assessment. The Operability Assessment was performed in response to Action Request 980800326 (the Action Request noted less than expected chiller performance).
As described in LER 1998-021, the reason for the Technical Specification violation during the 22 continuous days in the month of September 1998 was the miswiring of the low chilled water temperature cutout switc . Corrective Steps That Have Deen Taken and the Results Achieved
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As described in LER 1998-020, Corrective Actions 1: "On August 28,1998, the temperature control unit was replaced, and the chiller performed satisfactorily. The chiller was declared operable, returning Units 2 and 3 to full compliance with TS 3.7.10." J As described in LER 1998-021, Corrective Actions 1: "On September 25,1998, at approximately 1200, the chilled water low temperature cutout switch wiring was corrected. The chiller started satisfactorily. Following venting of the chiller's condenser, the chiller was declared operable at 1418 PDT on September 26,1998 (the time of full compliance with TS 3.7.10)."
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ENCLOSURE 2. Corrective Steps That Have Been Taken and the Results Achieved (continued)
The remaining corrective actions described in LERs 1998-020 and 021 were associated with avoiding further violations. The actions described in the LERs have been complete Three of the actions described in the LERs contain activities that do not include specific completion dates. The current status of these three actions is discussed belo ,
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LER 1998-020, Corrective Action 4, described a working group which would reexamine the adequacy of Operability Assessments (OAs) and revise the OA process, as necessary. The specific action described in the LER was to provide a
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scope and schedule to senior management. That action is complete. The working group is continuing to work on implementing the improvements they have identifie * LER 1998-021, Corrective Action 5, described an interim action relative to senior Operations management approving all retests, until completion of an evaluation of the retest program and revision of the procedure governing work authorization The evaluation and procedure revision are complete and the interim action was closed on November 18,199 . LER 1998-021, Corrective Action 6, described an interim action relative to the use of the temporary system alteration and restoration form (SO123-II-15.3) for all wiring requiring the lifting and landing ofleads, until completion of the lifting and landing leads and verification work practices evaluations. The evaluations are complete. (If a procedure is reviewed and determined to contain the protection /
control equivalent to that provided by the use of S0123-II-15.3 then the procedure can be modified such that the interim action no longer applies to that procedure.)
3. Corrective Steps That Will Be Taken to Avoid Further Violations No corrective actions, other than those described above, are planne . Date When Full Compliance Will Be Achieved As described in LER 1998-021, the Emergency Chiller was declared operable on ,
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5. Related Correspondence ]
Letter dated February 11,1999, from Dwight E. Nunn (SCE) to Document Control Desk (NRC) provided additional information related to the Probabilistic Risk Assessment (PRA)
evaluation of the chiller inoperabilitie I'
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. 1 ATTACIIMENT I CORRECTIONS / CLARIFICATIONS TO INSPECTION REPORT 98-18 I Enclosure 1 - Notice of Violation I
The procedure number reference for the Emergency Chilled Water Operation procedure should be j SO23-1-3.1 rather than SO23-1-1.3 (two places). i
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Enclosure 2 - Executive Summarv
The bulleted item which starts "Postmaintenance testing, as prescribed . " is listed under the >
heading of" Maintenance" while in the body of the repon this item is discussed under
" Operations."
The September Emergency Chiller inoperability was from September 4,1998 rather than September 3,1998 as stated. (Please note: Section 08.1.b.1 states correctly that the inoperability was from September 4,1998.)
Enclosure 2 - Report Details Section 08.1. The reference to the Control Room HVAC system is more appropriately the control room emergency air cleanup system rather than control room essential air cleanup system. (Applies throughout the inspection report.)
Section 08.1. The September Emergency Chiller inoperability was from September 4, 1998 rather than September 3,1998 as stated. (Please note: Section 08.1.b.1 states correctly that the inoperability was from September 4, 1998.)
Section 08.1. The first five sentences of this section attempt to describe the state of the chilled water expansion tank when it was found as well as the theoretical chilled water pump operation (based on the tank condition), if the chilled water pump would have been called upon to operate. Below is a redraft of those sentences reflecting our understandin For the occurrence with the Train A expansion tank full of water, the expansion tank pressure decreased to approximately 3.0 psig, which was the hydrostatic pressure that resulted from 70 feet of water in the chilled water piping above the expansion tank. The chilled water pump required approximately 4 psig suction pressure to avo.id _ cavitation from a loss of net positive suction head. .If ths _ chiller would have been started and operated, the pump suction could have decreased to approximatelyTIS ,
psig (the hydrostatic pressure only - assuming a vacuum at.the top of thb
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ATTACHMENT Enclosure 2- Report Details Section 08.1.b.4 (continued)
Milsdl$hh[ This 15 psig [ hydrostatic pressurejl exceeded the 4 psig required suction pressure. The chilled water pump would have provided
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approximately 69 psig discharge pressure (nbminst pump delta-p is 54 psi), given an expansion tank at 15 psig. The si9 psig would have been sufficient to pump chilled water throughout the chilled water pipin ..
Section 08.1. The HVAC technicians are the craft that set the electrical Last Paragraph demand switch rather than the I&C technicians, as stated. (The I&C technicians were responsible for the calibration of the low chilled water temperature cutout switch.)
Section M8.1. The low chilled water temperature cutout switch has three connection Second Paragraph points rather than the four state Section E8.1. The first sentence of the paragraph describes the requirements for the Second Paragraph use of a nonconformance report (NCR) to accept a condition "as-is" and justify that the configuration continues to satisfy design requirement The paragraph goes on to say that utilization of an NCR [rather than an Operability Assessment (OA)) in principle, would have caused increased engineering attention to the design of the chiller and the effect of the degradation on the chiller. SCE does not disagree with the assertion that an NCR in principle would have received increased attention, however, based on the conditions described in the Action Request (AR) and the actions outlined in the initial Field Support assignment of the AR, SCE believes an OA was the appropriate mechanism to evaluate the conditio The initial Field Support assignment indicated that there was a need to have the HVAC group investigate the thermostat setting, chilled water sensor and the control module. Therefore, there was no intention of accepting the condition "as-is." SCE concurs, however, that the OA was not accomplished in accordance with Procedure SO123-XX-1 and the inadequate OA resulted in a failure to promptly identify and correct a condition adverse to qualit