IR 05000271/1990010
| ML20062H579 | |
| Person / Time | |
|---|---|
| Site: | Vermont Yankee File:NorthStar Vermont Yankee icon.png |
| Issue date: | 11/27/1990 |
| From: | Rogge J NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I) |
| To: | |
| Shared Package | |
| ML20062H567 | List: |
| References | |
| CON-#191-11329, CON-#191-11330 50-271-90-10, OL, OLA, OLA-4, NUDOCS 9012050121 | |
| Download: ML20062H579 (52) | |
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U..S. NUCLEAR Ri?GULATORY COMMISSION
REGION I
Report No.
50-271/90-10 Docket No.
50-271 License No. DPR-28 Licensee:
Vermont Yankee Nuclear Power Corporation RD 5, Box 169 Brattle'ooro, Vermont 05301 Facility:
Vermont Yankee Nuclear Power Station Location:
Vernon, Vermont Dates:
August 13 - October 9,1990 Inspectors:
Harold Eichenholz, Senior Resident Inspector Thomas G. Hiltz, Resident Inspector Morton B. Fairtile, Project Manager, NRR Jason C. Jang, Sr. Radiation Specialist, DRSS Leonard S. Cheung, Senior Reactor Engineer, DRS Peter D. Drysdale, Senior Reactor Engineer, DRS Carl H. Woodard, Reactor Engineer, DRS Approved by:.
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~ dho F. Rogge, Chief,6(ca'litor Projects Section 3A Date I
Inspection Summary: Insocetion on August 13 - October 9.1990
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' Areas Insnected; Resident safety inspection of the following areas: plant operations, radiological
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controls, maintenance and surveillance, security, engineering and technical support, safety
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assessment and quality verification, and allegation followup.
Results: Inspection results are summarized in the attached Executive Summary.
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EXECUTIVE SUMMARY VERMONT YANKEE INSPECTION REPORT 50-271/90-10
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AUGUST 13 - OCTOBER 9.1990 Plant Operations A full reactor protection system actuation was received due to a spike in a shared local power range monitoring instrument while shutdown Corrective actions to address this event are not fully complete and the event report remains open. A proper safety perspective and an aggressive questioning attitude was exhibited during resolution of a refueling bridge interlock which inhibited scheduled opernions. Vermont Yankee management demonstrated a balance between acceptable equipment pcrformance and personnel ALARA considerations in resolving control rod
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drive (CRD) equipment problems.
A violation involving failure tc follow procedural requirements for operation of the spent fuel pool cooling system was identified during the followup of an allegation (VIO 90-10-04).
Radiological Protection Licensee corrective actions described in LER 90-05 appear adequate to prevent a repeat violation
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of containment air sampling requirements (NCV 90-10-07). Crbalt 60 was detected during exit whole-body counts taken on four contract employees. Management provided timely assessment of the health effects of the cobalt-60 uptakes and demonstrated an appropriate response to address turbine floor contract workers' concerns. The ALARA program effectiveness benefitted from several changes implemented during the refueling outage. Licensee corrective actions early in the refueling outage corrected deteriorating control of Radiation Work Permit (RWP) activities.
A non-cited violation (NCV 90-10-01) was caused by a contract worker who did not adhere to
. RWP procedures.
Maintenance and Surveillance The effect of potential clutch gear failure on motor operated valves was evaluated by Vermont Yankee. Implementation of the licensee program to ensure updated vendor information requires -
further assessment and is unresolved (UNR 90-10 02). The trial LCO preventive maintenance program was reviewed and potential weaknesses were identified (UNR 90-10-03).
LERs describing two missed surveillance events were evaluated.
The inspector reviewed core verification and control rod drive friction testing. Loading requirements for the monthly diesel generator operability test surveillance were not in accordance with Technical Specifications (NRC
. review of this issue is discussed in Report No. 50-271/90-80). A deviation from licensee written commitments was identified that involved inadequate dispositioning of inoperable EQ equipment (DEV 90-10-06). - This condition resulted from the inadequate manner in which the licensee.
evaluated and controlled maintenance activities on the "A" spent fuel pool cooling pump.
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Executive Summary Security A random cocaine drug search was considered a positive licensee initiative. Three incidents involving improper access control / clearance and fitness-for-duty are discussed and were the subject of a special NRC Region I security inspection (NRC Inspection Report 50-271/90-11).
Engineering and Technical Supoort
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Turbine control oil system responses are undergoing further evaluation during the post-outage turbine startup and an associated event report (LER) is considered open. The technical support and evaluation provided to assess Cycle 14 fuel failures demonstrated a strong technical competence. Due to the inability of the licensee's staff to properly identify and promptly correct degradation of the motor on the "A" spent fuel pool cooling pump from an EQ program perspective, a violation of 10 CFR 50, Appendix B and 10 CFR 50.49 was identified (VIO 90-i 10-05).
. Safely Assessment and Ouality Verification A NUREG-0737 commitment (Clarification of TMI Action Plan Items) item was reviewed and closed. An unresolved item (UNR 50-271/86-22 04) regarding whether the reliability of the ATWS RPT System is consistent with Generic Letter 85-06, was closed, The inspectors evaluated the effectiveness of the Vermont Yankee quality assurance program and determined that in general it was effective.
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l SUMMARY The inspectors reviewed the adequacy of the licensee's minimum shift stafRng F
requirements to accomplish a safe shutdown of the plant during a fire emergency. No
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undermanned conditions were identined, and the licensee staffing levels are consistent p
with the capability to provide for the safe shutdown of the plant during a fire emergency.
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The inspections associated with the manner in which the plant's SFP cooling equipment was operated and equipment was repaired, between the period of June 9,1989 and
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July 27,1990 identified a number of deficiencies involving the conduct of licensee activities. These included: (1) a violation involving the failure to follow the procedural requirements for operation of the SFP cooling system; (2) a deviation from licensee written commitments involving dispositioning of inoperable EQ equipment; and (3) a violation of 10 CFR 50, Appendix B and 10 CFR 50.49 requirements due to a failure to
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properly identify and assess degradation of safety related equipment from an EQ program perspective. These deficiencies appear to be attributable to a number of weaknesses involving: (1) the lack of safety committee reviews to assess the impact of degraded
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equipment conditions and planned corrective actions on facility design features and licensee commitments; and (2) a less than adequate understanding of the licensee's established EQ program as it pertains to addressing inoperable safety class equipment.
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Attachment A
3.
REVIEW OF CONCERN 3.1 Adequacy of Mi;)imum Shift Manning A.
Statement of Concern:
The licensee has undermanned operating crews, such that, they could not perform a safe shutdown of the plant during a fire emergency as required by Technical Specifications (TS).
B.
Discussion of Issue and Assessment The organizational requirements of Vermont Yankee (VY) are stipulated in the TS, the Security Plan, and station p.wcedures. The current TS requirements for minimum shift manning are in excess of the requirements stipulated in NUREG 0737, item I.A.I.3, Shift Manning, due to its specifying that a Shift Engineer is included in the minimum shift staffing.
Table I represents a correlation of the various TS and staffing requirements that currently exist. The station procedures adequately reflect both TSs and 10 CFR 50, Appendix R, Section Ill H requirements for the Fire Brigade. For example, the Shift Supervisor is not a member of the fire brigade, and the brigade staffing does not reduce licensed operator levels within the control room below TS requirements while at the same time providing for at least five members on each shift to be available for the Fire Brigade.
From a minimum staffing condition, the most limiting task would be the implementation of alternate shutdown capability at the same time that a fire emergency is declared. The emergency declaration would result in manning the Fire Brigade, in February 1988 the NRC reviewed the licensee's compliance with 10 CF,
,v, Appendix R. This review was documented in Inspection Report 50-271/88-04, which included an examination of the licensee's capability to achieve and maintain hot shutdown and the capability to bring the plant to cold shutdown conditions in the event of a fire in various areas of the plant. Station Procedure OP 3126, Shutdown Using Alternate Shutdown Methods, was reviewed to ascertain that the shutdown could be attained in a safe and orderly manner. No unacceptable conditions were identified.
The review included a walk-through of selected portions of the procedure to determine by simulation that shutdown from outside t ; control room could be attained in an orderly and timely fashion.. The procedure walk-through was accomplished by four members of the licensee's operations staff. The NRC review determined that the licensee did not have a time-
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Attachment A
i line analysis to verify that all procedure OP 3126 requirements could be implemented with the minimum manpower available. At the time of the inspection, the licensee committed to perform the time-line check. In response to the inspector's questions on the status of this item. the licensee's staff provided an Operations Department Memorandum dated August 24, 1988. This memorandum provided the required time line
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analysis of procedure OP 3126 using the available manpower associated with a declared fire emergency.
The inspector determined that the licensee's analysis was responsive to the NRC's concerns, s
The inspector determined that the licensee's minimum shift staffing
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requirements are consistent with the plant's licensing basis. The inspector identified no unacceptable conditions and based upon prior NRC inspections in this area, concluded that there is a proper level of assurance that the licensee has the capability to provide for the safe shutdown of the -
plant during a fire emergency.
3.2 Spent Fuel Pool (SFP) Cooling System Operations t
A.
Statement of Concern:
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The SFP cooling system relied upon defective equipment for an extended period of time. This condition was contrary to operability requirements
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for power operation of the plant. Because of an electrical fault on a SFP
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cooling pump the vital emergency core cooling system was threatened.
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Concern was expressed about the ability to cool the SFP if the reactor buildmg became uninhabitable, because there would be a dependence on only one pump and power supply. A question was raised about intentional oversight in not repairing the pump motor because the licensec.was to L
install a new SFP cooling system.-
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System Descriotion The SPF cooling and demineralizer system cou!s the fuel storage pool by transferring the spent fuel decay heat through a beat exchanger to the
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L reactor building closed cooling water system. Water ptaity and clarity in
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the storage pool are maintained by filtering and demineralizing the pool-
J water through a filter demineralizer.
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The system consists of two circulating SFP cooling pumps connected in
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L parallel, two heat exchangers, two filter demineralizers, and the required L
piping, valves and instrumentation. Each pump has a design capacity'
.l equal to' the system design flow rate and-is capable of simultaneous operation. Two filter-demineralizers are provided, each with a design l-
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capacity equal to the design flow rate. The pumps circulate the pool water
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in a closed loop, taking suction from the spent fuel storage pool, j
circulating the water through the heat exchangers and filters, and
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discharging it through diffusers at the bottom of the fuel pool and reactor l'
well.
The SFP pumps and heat exchangers are located in the reactor building
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below the bottom of the fuel pool.
The SFP filters, which collect radioactive corrosion products, are located in the radwaste building.
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p The SFP is filled and make-up is supplied from the condensate transfer
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system. Water is removed from the SFP via the fuel pool pumps through
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the filter demineralizer units to the condensate storage tank.
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- The operating temperature of the SFP is permitted to rise approximately 25 degrees F above the normal operating temperature (125 degrees F)
when circulation flow is temporarily interrupted or, when larger than
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normal batches of fuel are stored. The heat exchangers in the residual
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heat removal system can be used in conjunction with the fuel pool cooling
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and demineralizer system to supplement pool cooling in the event that a j
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larger than normal amount of fuel is stored in the pool.
i The system instrumentation is provided for both automatic and remote manual operations, instrumentation'and controls are provi'ed to detect,
L control and record pump operation, pool temperature and sys'em flow. A
a pool leak detection system has been provided to monitor leakige and thus
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indicate pool integrity.
g The pumps are controlled locally in the reactor building or at Panel 20 22
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in. the Radwaste Building control room. Pump low surtion pressure l
L automatically turns off the pumps. A pump low discharge pressure alarm p
indicates in the ' main control room and in the pump room. -
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y The safety objective of the fuel pool cooling and demineralizer system as j
stated in Section 10,5 :of the. FSAR,'is to maintain fuel pool-water;
temperature at a level which will prevent damage to the fuel elements, and to maintain the Reactor Building environment at a level which will bound the qualification of electrical equipment.
C.
SFP Licensing issues and' Commitments e
On April 25,1986, Vermont Yankee submitted its Proposed Change (PC)
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No.133 amendment request to the NRC to allow the expansion,of the capacity of the SFP and the increased storage of spent fuel in the pool,
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- Attachment A
If granted, the amendment to the facility operating license would authorize the licensee to increase the capacity from the current 2000 fuel assemblies to the proposed capacity of 2870 fuel assemblies in the pool. In the licensee's letter (FVY 87 65) to the NRC on June 11,1987, they responded to (PC No.133 related) NRC staff questions regaruing operational controls associated with the SFP cooling system by committing to administratively implement proposed controls by startup from the 1987 refuel outage. These administrative controls were presented in the form of proposed limiting conditions for operation (LCO) and associated surveillance requirements. The licenme further committed that these proposed controls would be submitted to the NRC for approval as a separate TS amendment request.
Subsequently, on September 1,1987, the licensee submitted its letter FVY 87-87 to the NRC that provided a summary of the administrative controls that they would procedurally implement prior to startup from the 1987 refuel outage. The administrative controls were intended by the licensee to provide assurance that adequate cooling was available for heat removal in the SFP by providing, in part, for fuel pool cooling equipment operability constraints and SFP and related equipment surveillances.
However, based upon discussion with the NRC staff about VY's SFP expansion reports, the licensee determined that incorporation of the operational controls within the TSs was not necessary and therefore an amendment request would not be submitted.
On February 9,1988, a public meeting was held between the NRC staff and VY to consider information needed to complete the staff's review of PC No.133. In order to expedite the NRC staff review of the subject license amendment request, VY committed to design, install, test and make operational, a redundant seismically designed SFp cooling system prior to the time that they exceed the existing 2000 spent fuel assembly storage limit in the SFP. The licensee's letter FVY 88-17, which was submitted to the NRC on hiarch 2,1988, documented and expanded upon the information presented at the public meeting. In addition, each of the remaining open technical issues was addressed. Specifically, the licensee addressed the single failure issue by stating that VY is single active failure proof with one SFP cooling pump in standby and one pump operating with
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two heat exchangers operating in parallel.
As a result of the above licensing issues and commitments, the VY hianager of Operations (hiOO) issued on hiarch 3,1987, hiOO Directive 87-1. This directive required the VY Plant hianager to administratively implement the conditions specified in their letter FVY 87-87 to the NRC.
Procedure OP 2184, Fuel Pool Cooling System; OP 4341, Fuel Pool Level Switch Calibration; and OP 0150, Responsibilities and Authorities of Operations Department Personnel, were revised accordingly.
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Attachment A
The NRC issued Amendment No.104 to the Facility Opert. ting License on May 20,1988. This amendment allowed for the re-racking, of the SFP to accommodate 2870 assemblies. However, the present TS limit of 2000 assemblies in the pool was not changed. Consideration of storage of more than 2000 assemblies was determined by the NRC to await a determination of the adequacy of SFP cooling for more than 2000 assemblies, including the yet to be designed enhanced SFP cooling system.
According to the licensee, the commitment to design and install a new enhanced SFP cooling system of and by itself addressed all of the NRC staff concerns on PC No.133. But, because the VY letter FVY 87 87 was incorporated by reference in Amendment No.104, it was judged by the licensee not to be worth the effort and possible additional complexity to attempt removal of the administrative controls. The licensee has indicated that the controls will rer..ain until after the new enhanced fuel pool cooling system is installed.
D.
SFP Pump A Operability An intermittent ground on the "A" SFP cooling pump motor was detected on June 9,1989. The ground, originally thought to be on the standby liquid control (SLC) system's tank heater, appeared only after the SFP pump motor had been operating for several minutes.
Additional investigation and data collection led VY personnel to the conclusion that the pump motot should be replaced. The decision to replace the pump motor vice rewinding the motor was based on a derived safety benefit from having a pump, albeit with a phase ground, in place in the unlikely event that the redundant "B" SFP cooling pump failed. On July 5,1989 the breaker for "A" SFP cooling pump was white tagged out of service due to the motor ground.
Between July 5,1989 and July 3,1990 the "A" SFP cooling pump was white tagged out of service.
A Maintenance Request (MR 89-2291)
remained active during this period, but no maintenance was performed.
Because the licensee thought that the motor would function if the white tag was removed and the breaker was closed, VY management considered the pump operable.
Following receipt inspection and disposition of dimensional deviations a new motor was installed by July 27,1990. The "A" SFP cooling pump motor power supply breaker was white tagged open and the pump was declared inoperable during the new motor replacemen.
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Attachment A
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The inrpector concluded that the "A" SFP cooling pump was inoperable between July 5,1989 and July 3,1990. Station Procedure AP 0140, Vermont Yankee Local Control Switching Rules, states that white tags (Danger Tags) provide visual indication that operation is not allowed for the protection of personnel or equipment or necessary to maintain system
integrity. Furthermore, AP 0140 Appendix B, Miscellaneous Switching and Tagging Rules, states that any component which is white tagged shall not be operated under any circumstances. Moreover, upon completion of an active corrective maintenance request the shift supervisor shall perform specified post maintenance testing (PMT), and based upon results of the PMT declare the equipment operable and close out the corrective MR.
This information is contained in AP 0021, Rev. 17, Maintenance Requests. Based upon the previously discussed procedural guidance, the inspector concluded that equipment or components positioned and white tagged to prevent operation shall be considered inoperable. A white tag used to administratively restrict operation of a component or equipment renders that equipment or component inoperable.
In some instances, where white tags are used only as a higher level of equipment control, the equipment may be made operable by removing the white tag and repositioning a breaker, switch, valve, or other tagged component.
VY committed to administratively implement certain controls prior to start-up from the 1987 refueling outage, as discussed in Section 3.2.C above.
The administrative controls were procedurally implemented in procedure OP 2184 and administratively implemented in Manager of Operations (MOO) Directive 87-01. One of these controls stated that from and after the date that one of the fuel pool cooling subsystems is made or found inoperable and the remaining subsystem is capable o maintair.ing the fuel r
pool temperature below 150 degrees F, then the wactor shall be in cold shutdown condition within thirty days unless such subsystem is sooner
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made operable. The inspector concluded that from July 5,1989 to July 3,1990 the "A" SFP subsystem was made inoperable and that the procedural controls of procedure OP 2184 were not implemented. This is considered a failure to follow a procedural requirement and is a violation of Technical Specification, Section 6.5 (VIO 50 271/90-10-04).
l The inspector concluded that this was an isolated event. However, the evaluation of the event identified two weaknesses which require additional licensee attention. First, operators and some key supervisors were not
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fully aware of the administrative requirements contained in the MOO
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Directive 87-01 and in the fuel pool cooling system operating procedure.
The MOO Directive was not readily available to operators, consequently, the decisions regarding repair of the "A" SFP cooling pump did not benefit from guidance contained in these instruction.
Second, the
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Attachment A
I sequence of events identified the need for PORC to review plant tagouts to detect any potential safety hazards. The licensee has identified this concern and PORC now conducts periodic reviews of plant tagouts which are active for greater than 60 days.
The inspector concluded that a procedural requirement, formally
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committed to the NRC, was not effectively implemented, and that management review did not adequately address the event or document the acceptability of the condition.
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E.
Environmental Ouall0 cation of the "A" SFP Cooling Power Motor Engineering Design Change Request (EDCR) 83-32, Fuel Pool Cooling
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EQ Modi 0 cations was implemented in 1984 by the licensee in order to meet the requirements of 10 CFR 50.49 and assure that safety related t
electrical equipment in the Reactor Building would not be subjected to a
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post-LOCA harsh environment from the SFP. The design change would assure operation of the SFP cooling system long term, post-LOCA with loss of off site power, and provide controls to the system when the reactor building was not accessible. The electrical portion of the SFP cooling system was reclassl0ed as safety class, and was required to be qualified to assure post LOCA operation when off-site power is not available. The
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modified SFP cooling system would be capable of operating post-LOCA, prevent the SFP from boiling, and thereby preclude creating a harsh
environment in the reactor building.
Since the SFP cooling pumps are safety-related and are required to be operable to maintain the ambient environment for which other safety-
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related components in the reactor building are qualified, the licensee -
l included the pump motors into the EQ master list, and qualified them in i
accordance with 10 CFR 50.49 requirements. Normally only one pump i
is required to maintain the fuel pool temperature. The second pump is required to operate when the first one fails.
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On June 9,1990, the plant Maintenance Department determined that an
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intermittant ground existed in the "A" SFP cooling pump motor.. With the pump stopped and' cold, testing' originally did not indicate a ground.
i-Subsequent testing determined that the ground appeared after about 15 to 20 minutes of operation when the motor, was hot and at operating temperatures. On July 5,1989, the power to the pump motor was de-
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energnized and the feeder breaker white tagged in the open position. The details of the troubleshooting, repair, and procurement efforts related to the ground condition are contained in Table 2, Sequence of Events. The motor was replaced with a new motor on July 27,1990.
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Attachment A
During the period from June 9,1989 to July 27, 1990, the "A" SFP cooling pump motor was in a degraded condition, in that at least one phase of the motor winding was shorted to ground. The licensee did not provide evidence to demonstrate that the motor, while in the degraded condition, was qualified for the post-LOCA environment. This is in violation of 10 CFR 50, Appendix B, Criterion XVI and 10 CFR $0.49, Paragraph f, which require nonconformances promptly corrected and electrical equipment important to safety to be qualified (VIO $0-271/90-10-05).
10 CFR 50, Appendix B, CMon XVI requires that measures shall be established to assure that conditions adverse to quality, such as defective equipment and nonconformances, to be promptly identified and corrected.
Although the licensee identified the deficiency of the pump motor on June 9,1989, corrective action was not accomplished until July 27,1990. In addition, NRC Generic letter 86-15 regarding information relating to compliance with 10 CFR 50.49, " Environmental Qualification of Electrical Equipment Important to Safety for Nuclear Power Plants," was issued to the licensee on September 22,1986. The letter clearly stated that when a licensee discovers a potential deficiency in the environmental qualification of equipment (i.e., a licensee does not have an adequate basis to establish qualification), the licensee shall make a prompt determination of operability, shall take immediate steps to establish a plan with a reasonable schedule to correct the deficiencies, and shall have written justification for continued operation.
In July 1990, after the degraded motor was replaced, the licensee generated various documents to argue that the degraded pump motor was operable during a postulated post-LOCA condition. For an ungrounded electrical power system, the pump motor can be operated even with one phase shorted to ground. However, there was no analysis available to prove that when the pump motor temperature increased during the post-LOCA condition a second phase would not short to ground, since the pump motor was in a degraded condition. The licensee already identified that the first phase of the motor winding shorted to ground when the motor warms up to normal operating temperature.
F.
SFP level InstrumentatiRD in 1983, the licensee identified the need to replace the existing SFP level alarm instrumentation. This was due to insufficient test documentation for the existing instruments, which would prevent the installed instrumentation from being included in the Vermont Yankee upgrade program for EQ of safety related electrical equipment. The installed instrumentation included a single high and low level alarm function (LSH 19-60 and LSL 19 60).
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Attachment A
In their June 29,1984, letter to the NRC, FVY 84 74, which provided information on the Vermont Yankee upgraded EQ Program, the licensee stipulated that the existing SFP level alarm instruments would be replaced with redundant class IE instruments.
The implementation of EDCR 83 32 during the 1984 refueling outage provided for the installation of redundant safety class level instrumenation. The instrumentation was EQ and provided conformance with 10 CFR 50.49. The replacement levelinstrumentrion consisted of two moj:: parts: the level sensor located in the SFP u..J the electronics.
Each sensor (of which there are two) has two sensing elements, an upper
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and lower, to detect high and low water levels. The low level alarm
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condition would occur at 251/2" below the top of the SFP. This alarm condition would cause the annunciation of the " Fuel Pool Cooling System Trouble" alarm in the control room and the " Low Level Fuel Storage Pool" alarm in the Radwaste Building control room. The power for the i
i level instruments was derived from the SFP cooling pump motor power supplies that are supplied from the emergency diesel generator.
Essentially, the "A" SFP cooling pump power energized the "A" level instrument channel of the redundant level instrumentation system for the I
SFP It was the design intent of the EDCR for the redundant level alarms to allow the plant operators to add water to the SFP as required. The post-LOCA makeup water operation can be performed manually in the
Radwaste Building.
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l The issuance of hiOO Directive No. 84-04 on August 3,1984 provided l-guidance that was intended to ensure that the licensee will remain in full
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compliance with the EQ Program.
Accordingly, the plant staff was
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directed, in part, that the SFP level alarm switches shall be operable. This guidance also clearly directed and limited the timeframes for corrective action if a deviation from the requirement occurs, it was the intent of the hiOO Directive to ensure that the potential for post accident en'.ironmentally induced problems are minimized. In April,1985, the
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Vermont Yankee EQ Plan superseded the hiOO Directive. The licensee
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stated in the Plan,Section V, Operability Requirements for Environmental Equipment and Components, that "...it is the policy of Vermont Yankee's
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corporate management that all-equipment and components which are
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addressed by Vermont Yankee's EQ Program shall be maintained operable
and fully environmentally qualified at all times, commensurate with the
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status of the plant." However, administrative controls are specified for actions the licensee will follow in the event the EQ status of a component
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becomes uncertain. In its letter FVY 85-40,' dated hiay 3,1985, the licensee provided the NRC with the in place administrative controls associated with. operability requirements for EQ equipment and
components. The stated administrative controls wm identical to those l
contained in the EQ Plan, Section _ _. - -
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Attachment A
The licensee committed to the NRC that whenever safety class equipment j
or components which are environmentally qualified but are not covered by the Vermont Yankee TS fail (are not operable), a.wn Conformance j
Report shall be generated with disposition of the discrepancy provided within 30 days. Corrective actions will be completed within the time frame specined in the approved NCR disposition. The NCR shall include a justincation for continued operation, in a June 15, 1984, Yankee Nuclear Services Division memorandum, it was noted that the Vermont Yankee Operations Department must be able to determine if any plant conditions that may occur during normal operation could impact the Design Bases of the EQ Program.
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memorandum summarized the equipment and conditions relied upon to
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control accident environments and ensure EQ is notjeopardized. This new redundant SFP level alarm switches were specified to be electrical components required to be gur. lined for single failure proof availability because they are equipment relied upon to control accident environments and ensure EQ.
On July 5,1989, the Operations Department, with the concurrence of the y
Maintenance Department, white tagged out of service the power supply for the "A" SFP cooling system pump. - This action also placed out of service
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the "A" channel of the redundant bl/lo level alarm instrumentation for the SFP. The equipment remained in this condition until July 3,1990.
The failure of the licensee to identify and disposition the loss of operability of the SFP level instrumentation with a Nonconformance Report is considered a deviation from their written commitment to the NRC_(DEV-50-271/90 10-06).
G.
Ground Detection As a result of the recent ground problem identined with the SFP cooling -
pump motor, the NRC inspected and evaluated the 480 Vac ground detection system used,- safety related Bus No. 9. Also the effect of the
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ground (for other than 4.
9Q related issue) on one phase of the motor was evaluated.
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The ground detection circuitry for this bus of the 480 Vac distribution system consists of a local ground detection voltmeter for each phase of the three phase bus. Operations Procedure AP 0150, Responsibilities and Authorities of Operations requires that the Auxiliary Operator (AO) take readings on the Bus No. 9 ground detection meters each shift. The readings are recorded on the AO round sheets (VYAPF 0150.05), which
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Attachment A
requires the voltage readings be within 15 Vac of each other. Out of speciGeation notations on the round sheets are circled. A bases for the 15 Vac difference value could not be determined.
As indicated in Table 2, Sequence of Events, the events associated with the ground were initiated by a ground alarm corvlition on the Standby Liquid Control (SLC) system's tank heater. The SLC tank heater and the
" A" SFP cooling pump motor are both connected to Bus No. 9 480 Vac distribution system at Motor Control Center 9B.
The SLC tank heater's 480 Vac power supply is equipped with a " heater short-out" detectic.. circuit which provides local indications and a control ro ini alarm for identifying this condition, which can occur on any of the three phr.ses. The design of this detection circuit utilizes a high impedance to ground on each phase. This intentional ground can, and has, created an interaction with the Bus No. 9 gr, ad detection because the ground is intermittent (i.e., the heater turns on and off). Further, if the magnitude of the ground differs between phases, it will produce a differential voltage on the ground detection meter which could cause confusion. Essentially, a ground anywhere in the Bus No. 9 480 Vac distribution system will be sensed by the SLC heater short out alarm circuit.
A review of the licensee's actions taken following the receipt of the SLC tank heate: ground alarm was determined by the inspector to have resulted in a prompt investigation and corrective actions. These actions led to k>cating the original source of the ground and the realization that the SLC tank heater short-out detection circuit also detected the ground condition on the pump motor. A calibration analysis for the circuit revealed that the alarm.alay was set to ick up at 24 volts rather than the 42 volts as requirco.
.ppropriate adjustments were made to circuit components.
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Since this circuit also depends upon differences on phase voltage for an alarm condition, the 42 volt setting should make it less sensitive to high impedance grounds than the Bus No. 9 ground detection circuit.
Observations made by the inspector include the following:
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A bases for the maximum voltage difference for the voltage to ground readings for the Bus No. 9 ground detections circuit was not established.
The bases equate the minimum acceptable impedance to ground for each phase. The meter rea< lings did not correlate to the impedance of the ground.
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Attachment A
The effect of the SLC tank heater deliberate high impedance
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ground was not factored into the system. Interactions between the two systems need to be determined and evaluated.
Operator training did not address these interactions.
Procedures did not include opera'or response and actions required
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when the voltage differences exceed the established maximums.
The licensee's maintenance personnel were responsive in locating
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the ground and in addressing SLC tank heater short out alarm calibration problems.
Effective ground detection on an ungrounded electrical distribution
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system can be most beneficial by detecting equipment and circuit weaknesses before these weaknesses cause an equipment failure or an interruption in the power feed (s) associated with the system.
Based upon this discussion, the inspector determined that VY maintenance personnel followed good practices for operation of an ungrounded distribution system by isolating the grounded motor.
Licensee records and documents indicate that from the time the ground condition on the motor was diagnosed until the motor replacement was effected, the motor was only energized (and then only po'entially challenged the security of the electrical system) to conduct further maintenance investigatians.
As a result of discussions -with VY personnel, the inspector determined the licensee exhibits a proper regard for not using grounded equipment for routine operations.
H.
Safety Assessment The SFP cooling system was designed to provide the capability to remove decay heat from the pooi and maintain the pool temperature below the TS temperature limit for 150 degrees F. la achieving this safety objective, the reactor building environment is maintained within the bounding halts of the environmental qualincation of electrical equipment. Essentially, the SFP temperature must be maintained below boiling. A single train of the two trair mtem is capable of performing 'his function. All electrical equipmes r.,r this system was designed to. meet EQ requirements.
Specincally, the maximum post accident reactor building temperature is 115 degrees F and the radiation level within the building assumes a TID 14844 core damage source term Because of the "beyond design bases accident" assumed source term, the manually started pumps can be controlled from the shielded environment of the radwaste building.
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Attachment A
Due to the ground on the "A" SFP cooling pump, and because it was l
believed to be prudent to not operate the pump with this condition t'nless
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it was necessary, the feeder breaker supplying power to this pump was white tagged in the open position. This feeder breaker is on a motor
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control center located within the reactor building.
Thus, the plant
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operators would be required to enter the reactor building to restore power
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is this pump prior to its use. The licensee's actions also resulted in de-activating one of the two redundant level alarm instrumentation channels l
provided to monitor the SFP level.
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The following facts and conditions are relevant in assessing the impact of i
the licensee's actions on plant safety:
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At least 36 feet of water is maintained in the SFP (a TS limit),
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The "A" SFP cooling pump was de-energized approximately 145 i
days following the last refueling. The licensee's calculations, l
assuming an initial SFP temperature of 100 degrees F, determined
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that a total loss of cooling would cause the pool temperature to reach 150 F within 40 hours4.62963e-4 days <br />0.0111 hours <br />6.613757e-5 weeks <br />1.522e-5 months <br /> and boilding would occur 90 hours0.00104 days <br />0.025 hours <br />1.488095e-4 weeks <br />3.4245e-5 months <br /> from the initiation of the :oss of cooling event. Thus, sufficient time for plant operator actica exists.
According.to the licensee's analysis, the reactor building is
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accessible following the design basis accident described-in the FSAR. Thus, a plant operator could enter the reactor building,
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close the feeder breaker and manually start the subject pump well l
before boiling of the pool initiated. - However, given the ground condition of the pump and considering the elevated temperature of the building, the ability of the pump to perform its fuction in an elevated temperature environment is questioned. For the case of post-accident reactor building access and a loss of the normal SFP cooling function, plant operators can manually initiate augmented SFP cooling using the Residual Heat Removal System.
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The plant design assumes a loss of normal power as part of the design basis LOCA. Following the automatic loading of plant equipment on an emergency deisel generator, a SFP cooling pump L
is started. Therefore, the starting of the pump from the radwaste building is an envisioned manual action, and the only unanticipated action would be the need to enter the reactor building.
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The NRC requested the licensee to conduct an evaluation of the consequences of their actions that could have resulted from de-l energizing the "A" SFP coo'ing pump.
They calculated the l-l I
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Attachment A
j probability of a scenario leading to core damage, plus the need to j
energize the non-operal.lg pump to maintain fuel temperature below boiling, as in the order of 10 E-6 to 10 E-7 per reactor year.
Taking credit for the "A" SFP cooling pump reduces the probability of exceeding the SFP temperature limits to 10 E-7 to 10 E-8 per reactor year.
However, assuming the worst case conditions, the licensee's calculation shows that the SFP can be maintained below boiling by feed and bleed using the condensate transfer system in the radwaste building. Although not currently.
proceduralized, this potential plant response is viable to address the case of a loss of habitability of the reactor building. The licensee has an off-normal response procedure ON 3157, Loss of Fuel Pool Level.
For the case of an inaccessible reactor building, this procedure provides instructions for SFP makeup via the operation of the condensate transfer system equipment located in the radwaste building, f
With regard to the loss of one of the two redundant SFP level
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instrumentation channels, and assuming single failure conditions, a number of additiona' alarm features - pertaining to SFP temperature are available to the plant operators in the control
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room. Had temperature indications, either in the vicinity of the SFP or the pool itself, been indicative of a loss of SFP cooling condition, the re-energization of the "A" SFP cooling pump of an
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by itself would have retumed the redundant level channel to service. It is the use of the high and low level alarms that aid the plant operators in maintaining the correct level within the pool where normal makeup operations are not performed within the immediate area of the SFP.
Although it is of concern to the NRC that the licensee de-energized and relied upon a degraded SFP cooling pump, it is apparent that a number of
installed design features provide appropriate means of mitigating the consequences of the licensee's actions.
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TABLE I TO ATTACIIMENT A
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VERMONT YANKEE MINIMUM SilIFT STAFFING REOUIREMENTS Minimum 5-Member Alternate Shutdown Assignment ***
Minimum TS Fire Brigade *
Fire Emergency Fire Emergency Shift Stafnng*
(TS 6.1.E)"
Not Declared Declared Table 6.1.1 Required:
Shift Supervisor (SRO)
Operator #1 Supy, CR Op ator (SRO) -
Operator #1 Operator #2 CR Operator (RO)
Operator #2 Operator #3 CR Operator (Alternate CRO with RO License)' Memoer #1 Operator #3 Operator #4 Or Or Auxiliary Operator Member #1 Operator #4 Operator #4 Auxiliary Operator Member #2 Shift Engineer Member #3 (Brigade Commander)
RP Technician Member #4 (TS 6.1,D.1)
Security Personnel Member #5
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Procedure AP 0894, Shift Staffing / Overtime Limits, identiGes the shift personnel requirements for plant operations, including Fire Brigade Duties. TSs require that a
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minimum of two operators shall be in the Control Room, during startup or operations, at least one of these operators must be a senior operator.
Procedure OP 3020, Fire Brigade and Fire Fighting Procedure, designates personnel
trained to be Gre brigade members and the composition of the on-duty brigade, The Alternate CRO and one of the Auxiliary Operators are interchangeable in terms of brigade duties.
Procedure OP 3126, Shutdown Using Alternate-Shutdown Methods, designates the
personnel assignments, within the constraints of the minimum shift staffing, which are -
necessary to provide safe ' hutdown from outside the control room. The Alternate CRO s
and Auxiliary Operator are interchangeable in terms of fire brigade and alternate shutdown assignment '
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TABLE 2 TO A1TACilMENT A SEOUENCE OF EVENTS
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DAIT; EVENT 05/26/89 Initiated MR-2160 to investigate ground alarm on the Standby Liquid Control (SLC) system's tank heater.
i 06/09/89 SLC ground alarm discussed at weekly OPS meeting.
06/09/89 investigation determines ground on Bus No. 9 is due to "A" SFP cooling pump (or P9-1 A) and not SLC tank heater. Ground occurs after operating pump
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approximately 20 minutes, MR 89-2291 initiated.
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06/12/89 MR 89-2291 assigned to Maintenance Department to investigate and repair cause i
of ground.
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06/13/89 Operations releases pump P9-1 A to maintenance to conduct investigation, electrical breaker opened, electrical meggar indicates no phase to ground short.
06/14/89 Pump P9-1 A white tagged out of service for the day for maintenance to obtain i
d installed equipment data (Tagging Order 89-1362)
06/15/89 Fuel pool level switch "A" calibration perft ed by I&C Department in
- accordance with procedure OP 4341. Qualification Documentation Review (QDR)
package No. 9.5 specifies 18 month calibration requirement (next due 12/15/90).
06/15/89 Maintenance Department initiates a Requisition (No.11050) to procure on a routine priority a replacement motor for pump P9-1 A. Date needed is specified as 10/15/89. Purchased item is classified as Safety Class Electrical, Seismic required, and EQ required.
t 06/16/89 Weekly OPS meeting notes that Maintenance Department could not identify the source of the ground on P9-1 A; may be temperature induced.
06/23/89 Weekly OPS aceting notes same status as 6/16/89 entry above and that Operations Department is considering restarting pump.
06/24/89 Pump P9-1 A restarted, ground reappeared within approximately I hour.
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06/29/89 Acting Maintenance Supervisor approves Requisition No.11050. Date needed is I
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changed to 08/01/89 and procurement priority is changed to an emergency status.
06/30/89 Weekly OPS meeting notes same status as 6/16/89. Operations Department restarted pump P9-1 A, ground reappeared. Maintenance investigating.
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s Table 2 to Attachment A
07/05/89 Operations Supervisor (OS) agrees with hiaintenance Department for SFP cooling pump P9-1 A to be white tagged out of service due to motor ground. Opening circuit breaker for pump on hiCC-9B also places out of service one of the two redundant Hi/Lo level alarm instrumentation systems for the SFP. Electrical meggar readings indicate a dead short phase to ground.
Digital Ohmmeter indicates 1500 ohms phase to ground, hiaintenance Department did not review equipment tag out to assess impact on the SFP level instrumentation system.-
Acting maintenance supervisor considers pump inoperable, but is not aware of existence of hianager of Operations (hiOO) directive 87-01.
07/07/89 Weekly OPS meeting notes that the hiaintenance Department has ordered a new motor for pump P941 A. (NOTE: This is the last raention of this issue as an outstanding item in the meeting minutes.)
07/17/89 Pump motor vendor responds in writing to licensee verbal request for quotation -
specified a 36 week delivery.
08/17/89 Following licensee's Procurement Engineering and Yankee Atomic Electric Company's Yankee Nuclear Services Division reviews for technical and quality requirements, Requisition No.11050 is issued as hiaterial and Service Purchase Request No. 89179.
08/22/89 Purchase Order (PO) No. 39059 is issued to pump motor vendor for delivery of x
a new motor by 05/15/90. At about this time hiaintenance Department instructs
, Purchasing Department to investigate purchase from an alternate vendor and the possibility of refurbishing the existing motor.
09/06/89 &
Pump motor vendor acknowledgement of receipt of PO No. 39059 09/12/89 specifies a shipping schedule of 05/10/90.
09/12/89 Alternate pump motor vendor submits a quotation on a replacement motor at almost six times the cost of PO 39059 and an estimated shipment of between 26-
.36 weeks.
03/25/90 Fuel pool level switch calibrations scheduled to be performed per procedure OP 4341.
03/30/90 Fuel pool level switch "B" calibration performed. OP 4341 lists as a discrepancy the inability to perform the " A" instrument channel calibration due to.... FP "A" pump motor burned up; breaker W/T open. Closed breaker provides power for a level instruments, cannot do " A".
04/02/90 Shift Supervisor (SS) acknowledges on VYOPF 43.41.01 the status of the subject instrument calibrations.
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Table 2 to Attachment A
05/22/90 Purchasing Department contacted pump motor vendor on status of delivery.
Licensee informed, due to problems with testing the new motor, that a new shipping date of 07/30/90 was established. PO turned over to licensee expeditor to follow item.
05/25/90 Pump motor vendor advised by expeditor that motor is required for fuel pool but, not a Technical Specification or LCO item. New scheduled shipping date of 06/22/90 established. New motor being fabricated had to be rewound and requalified.
05/29/90 thru Licensee's Purchasing Department contacted pump motor vendor at least 14 times 06/27/90 to expedite delivery and exploring alternatives for obtaining a new equivalent motor.
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05/30/90 I&C Engineer (who performs the duties of the I&C Department Surveillance Test (approx)
Coordinator) av.
3 that " A" fuel pool level instrumentation was not completed, reviewed MOO Directive 87-01, and informed Assistant Operations Supervisor (AOS) of issue. AOS did not know if directive was still in effect. He would review matter with OS and research issue.
06/15/90 1&C Engineer contacted AOS, who had not researched issue as of this time.
-(approx)
He then contacts the SS on duty to ascertain status of the MOO directive. The SS could not find any information on the MOO directive, i
06/26/90:
1&C Engineer requests the Operations Staport Department (OSD) Liaison Engineer to determine the status of the MOO Directive.
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06/27/90-Liaison Engineer reviews status of the SFP cooling system, procedures, licensing documents and delivery status of the new motcr He concludes that the administrative controls contained in MOO Directive 87 01 were still in effect and
the commitment to the NRC that would implement those controls were still applicable.
06/27/90.
Licensee hires a dedicated truck to pick up new motor at vendor facility.
06/28/90 New motor received at plant.
06/28/90 Plant Manager was briefed on the issue, directs that a review of NRC
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correspondence be conducted to ensure that the intent of the MOO Directive had not been withdrawn.. Operations Supervisor (OS) considers pump operable with white tag and de-energized, in part because no maintenance work was performed.
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Table 2 to Attachment A
06/29/90 During receipt inspection of the new motor, hiaterial Disposition Request (hidr)
No.90-100 was issued to document a number of discrepancies between the PO requirements and the as received unit. These discrepancies include dimensional, ratings, characteristic and documentation deviations.
07/03/90 White Tag on "A" SFP cooling pump is cleared, breaker is closed making power available to pump, and a Caution Tag is issued for the pump that stipulates to leave the pump in the OFF position and for emergency use only. This action appears to have been taken at this time to resolve, for the time being, questions the licensee had about the ability of the tagged out of service pump to perform its EQ Program safety function. The issues raised were subsequently documented in a 7/20/90 licensee memorandum.
07/16/90 Licensee conducts meeting on Vermont Yankee (VY) EQ Program requirements associated with " A" SFP cooling pump. Questions were raised as to the intent of the 10 CFR 50.49 Rule and Section V.2.1 of the VY EQ Program Plan, which addresses the operability of EQ safety-related equipment not covered by VY TSs.
OSD was to pursue interpretation of the rule to ascertain if reportability and/or corrective actions are warranted.
07/17/90 Pump motor vendor certifies dimensional deviation as acceptable to meet motor performance and seismic qualification.
07/20/90 Technical evaluation and justification is provided for hidr 90-100, and disposition is to use motor as is.
07/24/90 New motor for pump P9-1 A released from stockroom.
07/24/90 Licensee contracts with consultant to provide engineering services to review the VY EQ Program Plan, specifically Section V.2-1 and to provide guidance with respect to EQ equipment operability and compliance to the EQ rule. The licensee's compliance and reportability of the SFP cooling pump case was to be specifically addressed as well as any generic implications.
07/25/90 Pump P91 A released for work by the SS. A white tag is issued and the motor breaker is tagged open. Senior Control Room Operator lists the " A" SFP cooling pump as inoperable in the shift turnover log. A 30 day time limit is specified in
. accordance with hiOO Directive 87-01. Operations Department considers the pump available but not operable.
07/27/90 hiotor replacement complete, white tag is cleared and motor breaker is shut. A Caution Tag was issued to indicate that a Nonconformance Report (NCR) by the hiaintenance Department is outstandin.r-
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rip Table 2 to Attachment A
07/30/90
~ Maintenance Department Senior Engineer requests via OSD the services of YNSD engineering to prepare an.EQ NCR due to incomplete EQ documentation and preparation of a QDR for the new motor, The request notes that the 30 day time
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limit specified in the EQ program to develop the NCR expires on 08/24/90.
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' 08/01/90 PORC reviews " A" SFP cooling pump motor replacement. Notes problems with
' associated EQ documentation, that the issue will be resolved by the NCR process, and the motor will not be declared operable until this issue is resolved.
t 08/10/90 YNSD engineering responds to the service request, notes that an NCR is not required for the newly installed pump, and provides EQ documentation to meet EQ Program requirements, t
08/10/90.
Licensee's EQ consultant provides a summary report on the operability and qualification' status of the SFP cooling pump motor, with a conclusion that the qualification of the motor with the ground was not compromised.
08/15/90 Caution Tag on " A" FPC cooling pump is cleared, inoperability in Shift Turnover Log is closed, a
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