IR 05000271/1997004

Insp Rept 50-271/97-04 on 970420-0531.Violations Noted.Major Areas Inspected:Operations,Engineering,Maint & Plant Support

ML20141G921
Person / Time
Site:	Vermont Yankee File:NorthStar Vermont Yankee icon.png
Issue date:	07/07/1997
From:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
To:
Shared Package
ML20141G915	List: ML20141G912 ML20141G916 ML20141G921
References
50-271-97-04, 50-271-97-4, NUDOCS 9707110312
Download: ML20141G921 (61)

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i U.S. NUCLEAR REGULATORY COMMISSION REGION I t l

Docket N Licensee N DPR-28

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Report N i Licensee: Vermont Yankee Nuclear Power Corporation '

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l Facility: Vermont Yankee Nuclear Power Station l >

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l Location: Vernon, Vermont l l

Dates: April 20 - May 31,1997  ;

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! Insp'.sctors: William A. Cook, Senior Resident inspector  !

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Edward C. Knutson, Resident inspector  !

Edward B. King, Physical Security inspector George W. Morris, Reactor Engineer l Approved by: Curtis J. Cowgill, Ill, Chief, Projects Branch 5 l Division of Reactor Projects t

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i 9707110312 970707 PDR ADOCK 05000271 G pg 3

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EXECUTIVE SUMMARY Vermont Yankee Nuclear Power Station NRC Inspection Report 50-271/97-04 This inspection included aspects of licensee operations, engineering, maintenance, and plant support. The report covers a six-week period of resident inspection. In addition, it includes the results of physical security inspections by a physical security specialist and a regional reactor enginee Operations A reactor scram occu red from 100 percent power due to personnel error while performing local power range inonitor calibration, when two average power range monitor channels were inapproprittely taken out of bypass while they were set to zero power. This failure to adhere to the calibration procedure was contrary to Technical Specification 6.5 and was a cited violation. Operator response to the transient was very good and, with some minor exceptions, plalt response was normal. The licensee concluded that the root causes of this event were pemennel errors in the areas of work practices and communication Immediate and long-term corrective actions appeared to have adequately addressed the identified weaknesses. (Section 01.1)

Following completion of a nine-day maintenance outage, the subsequent plant startup and return to full power operation was well controlled. (Section 01.2)

A weekly surveillance revealed that oxygen concentration in the torus air space was greater than allowed by Technical Specification (TS). Prompt action was taken to verify this result and to reduce oxygen concentration to within TS limits. The condition was preliminarily determined to be due to inadequate nitrogen purging during containment inerting following plant startup. It also appears to have been the result of an unforeseen consequence of a recent change to eliminate the procedural option to inert the drywell and torus in parallel. Pending further inspector review, this issue was unresolved. (Section 01.3)

VY declared an unusual event (UE) based on receipt of a seismic monitor alarm. The cause of the alarm was later determined to have been a spurious indication from a single accelerometer, and the UE was terminated. Although, the event was correctly classified in accordance with the emergency procedures. (Section 01.4)

Severalinstances of weak operator performance were noted. The inspector was concerned that the number and nature of these instances was above normal. These observations and concern were discussed with and acknowledged by VY station management. (Section 04.1)

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Maintenance The licensee's decision to shut down for repair of main steam bypass valve, V2-77, was i the result of a thorough review of the available repair options. Licensee preparations for this maintenance were thorough. The outage duration was extended primarily due to '

! emergent maintenance that could not have been foreseen going into the outage. These j issues were appropriately addressed prior to plant restart. (Section M2.1)

l Post scram review of individual control rod scram times revealed that one rod was l significantly slower than the others. During subsequent scram time testing, the rod did not l l insert when scrammed. The cause was determined to be a defective scram solenoid pilot l l valve (SSPV) assembly. VY had replaced all SSPVs during the 1996 refueling outage, with l units that are unique to VY in this application. The f ailed SSPV was returned to the vendor (Automatic Valve, or AVCO), who determined the cause to be binding of one of the two l solenoid plungers. The binding was the result of wear products that were produced by  ;

l cyclic impact (induced by the 60-cycle AC solenoid) of the plunger on the plunger j

backseat. The failed SSPV had been noted to be buzzing, along with nine other SSPVs, at the beginning of the operating cycle. As a result, VY inspected the remaining nine SSPVs

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- that had been buzzing, and found evidence of wear on all of the associated plungers. No i l significant wear indications were observed on the plungers in solenoids that were not burzing= VY concluded that solenoid buzzing could be used as a reliable indicator of incipient failure, and listituted periodic checks for noise. The root cause of this failure mechanism is currently under investigation. (Section M2.2)

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Enaineerina The emergency diesel generator (EDG) service water flow control valves are air-operated and were found to be supplied via non-nuclear safety related (NNS) pressure regulators in the instrument air system. A failure of the NNS pressure regulators could cause the flow control valves to failin the closed position, which would isolate service water cooling flow through the EDG heat exchangers. The discovery of this system design vulnerability was made by the NRC Architect Engineering Team. A more detailed examination and summary of this finding will be documented in their report. (Section E1.2)

The VY Individual Plant Examination of External Events review identified that failure of several non-seismic piping systems could adversely impact safety related equipmen However, the licensee's immediate systems operability assessment concluded that the '

identified piping, although not seismic category 1, was of sufficient design and strength to withstand design basis earthquake dynamic loading. (Section E7.2)

NRC reviewed the licensee's capability to meet station blackout backup electrical ,

requirements. The licensee satisfies 10 CFR Part 50, Appendix A, GDC 17, " Electric  !

Power Systems," and has committed to come into full compliance with 10 CFR 50.63 prior to start-up from the 1998 refuel outage. (Section E8.1)

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) A regional specialist visited the site and YNSD during this inspection period. The specialist

reviewed the Vernon tie line cable testing and found it acceptable. The inspector also i

provided an update for Violation 50-271/96-09-06 corrective actions. One inspector

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followup item was opened as a result of those visits on the electrical circuit model used to support the evaluation of voltage dip during start of the fire pump. (Section E2)

Plant Suonort The licensee maintained an effective security program. Management support was evident based on the effective implementation of the security program. Management controls for identifying, resolving, and preventing programmatic problems were effective, audits were thorough and in-depth, alarm station operators were knowledgeable of their duties and responsibilities, and security training was being performed in accordance with the NRC-approved training and qualification plan. The licensee's provisions for land vehicle control measures satisfy regulatory requirements and licensee commitments. Vehicles were being properly searched prior to permitting protected area access, as required in the Plan and applicable implementing procedures. (Section S)

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l TABLE OF CONTENTS -

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EX EC UTIV E S U M M A RY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ii TAB LE O F C O NT ENTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . v I Summ ary of Plant Status . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 i

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l. Operations .................................................... 1  ;

O1 Conduct of Operations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 l 01.1 Reactor Scram Due To Personnel Error During Nuclear i instrument Surveillance Testing ........................ 1 .

01.2 Plant Startup and Return to Full Power Operation . . . . . . . . . . . . 4 l 01.3 (Open) Unresolved item (97-04-02): high oxygen concentration l in the torus air space during plant operations . . . . . . . . . . . . . . . 4

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01.4 Unusual Event Declared due to Indication of a Possible Seismic Event ........................................... 6 04 Operator Knowledge and Performance . . . . . . . . . . . . . . . . . . . . . . . . . 7 04.1 Operator Performance Observations ..................... 7 II. Maintenance .................................................. 8 M1 Conduct of Maintenance .................................. 8 i

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M1.1 Maintenance Observations . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8  !

l M1.2 Surveillance Observations ............................ 8 I M2 Maintenance and Material Condition of Facilities and Equipment ...... 9

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M2.1 Planned Mini-Outage for Repair of Main Steam Bypass Valve V2-77........................................... 9 M2.2 Scram Solenoid Pilot Valve Malfunction . . . . . . . . . . . . . . . . . . .10 M2.3 Main Station Transformer Oil Leak ..................... 12 l 111. En g i n e e ri n g . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 El Conduct of Engineering .................................. 12 E1.1 Emergency Diesel Generator Potential Common Mode Failure .. 12

! E2 Engineering Support of Facilities and Equipment . . . . . . . . . . . . . . . . . 16 E2.1 Post-Modification Test of the Vernon Tie 5 kV Cable ........ 16 E7 Quality Assurance in Engineering Activities .................... 17 E7.1 RHR Service Water Flow Requirements . . . . . . . . . . . . . . . . . . 17 l E7.2 Individual Plant Examination of External Events (IPEEE) Review issues.......................................... 17 E8 Miscellaneous Engineering issues . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 E (Closed) Follow-up Item 50-271/97-02-07: offsite electrical power sources ................................... 18 E8.2 (Closed) LER 50-271/97-007: inadvertent primary containment isolation system actuation due to a spurious spike on a reactor building vent radiation monitor, dated May 21,1997 ........ 19 v

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l IV. Plant Support ................................................ 22 S1 Conduct of Security and Safeguards Activities . . . . . . . . . . . . . . . . . . 22

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S2 Status of Security Facilities and Equipment .................... 22 S2.1 Alarm Stations and Communications . . . . . . . . . . . . . . . . . . . . 22 SS Security and Safeguards Staff Training and Qualification .......... 23 S6 Security Organization and Administration . . . . . . . . . . . . . . . . . . . . . . 24 S7 Quality Assurance in Security and Safeguards Activities . . . . . . . . . . . 24 i

' S7.1 Effectiveness of Management Controls . . . . . . . . . . . . . . . . . . 24 }

S7.2 Audits ......................................... 25 S8 Miscellaneous Security and Safety Issues ..................... 26 S8.1 Vehicle Barrier System (VBS) ......................... 26 -

S8.2 Bomb Blast Analysis ............................... 27 l l

S8.3 Procedural Controls . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27 _j

V. Ma nagem ent Meetings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27 Exit Meeting Summ ary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

' Management Meeting Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28  :) Review of Updated Final Safety Analysis Report (UFSAR) . . . . . . . . . . 28

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INSPECTION PROCEDURES USED . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29 ITEMS OPENED, CLOSED, AND DISCUSSED . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30 l

PARTIAL LIST OF PERSONS CONTACTED . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31 i LI ST O F AC R O NYM S U S ED . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32 ENCLOSURE 3 .................................................. 33 I

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Report Details Summarv of Plant Status At the beginning of the inspection period, Vermont Yankee (VY) was operating at 100 percent reactor power. On April 24, an inadvertent reactor scram occurred due to personnel error while performing a nuclear instrumentation surveillance. The plant utilizsv the unplanned shutdown for early commencement of a scheduled maintenance outag -

Emergent work on the main transformer extended the original two day outage duratir - hy approximately one week. A reactor startup was performed on May 7 and full pow?  !

operation was achieved on May 9. The plant operated at 100 percent reactor pc er for the remainder of the inspection period with the exception of power reductions to conduct planned surveillance testin . Operations

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01 Conduct of Operations' ,

O 1.1 Reactor Scram Due To Personnel Error Durina Muclear Instrument Surveillance Testina Inspection Scope (71707)

l The inspector observed operator response to an inadvertent reactor scram that j occurred on April 24, and reviewed the licensee's investigation of the cause and ~

actions to prevent recurrenc Observations and Findinas On April 24 at 9:10 a.m., a reactor scram occurred from 100 percent power. The )

cause of the scram was personnel error while performing local power range monitor 1 (LPRM) calibrations; specifically, two average power range monitor (APRM, an i instrument that uses the output from several LPRMs to determine average power) )

channels were inappropriately taken out of bypass while they were set to zero l power, which generated a reactor protection system (RPS) scram signal (APRM downscale). Plant response was as expected; all rods fully inserted, the main turbine tripped, and the turbine bypass valves operated to control reactor pressur The rapid power reduction caused reactor water level to decrease to less than 127 inches (normal operating level is 160 inches), which produced primary containment isolation system (PCIS) isolations of group 2, (drywell drains and portions of the RHR system) group 3, (drywell ventilation), and group 5 (reactor water cleanup system). Feedwater control system response, along with level swell caused by reactor heating of the feedwater, subsequently caused reactor water level to exceed the high level trip setpoint for the reactor feedwater pumps. Feedwater pump i restart was complicated by a failure of the condensate flow control valve automatic

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controller, but a pump was successfully started after the controller was placed in 1 l the manual mode. Reactor vessel level was then stabilized at its normal level. The

! reactor scram and PCIS actuation was reported to the NRC operations center (EN

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32213) as required by 10 CFR 50.72.

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' Topical headings such as 01, M8, etc., are used in accordance with the NRC standardized reactor inspection report outline. Individual reports are not expected to address all outline topic .

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The licensee had been planning to perform a controlled shutdown on April 29 for a two day mini-outage, primarily to repair a leaking main steam bypass valve. Rather than restarting the unit to operate for only four days, VY management decided to commence the scheduled outage early. Following single rod scram time testing and inspection of the drywell, plant cooldown was commenced on April 25, and cold shutdown conditions were established at 12:30 p.m. Outage activities are discussed in section M2.1 of this repor The inspectors arrived in the control room several minutes after the scram. The inspectors obserfed that the operators were responding in accordance with the scram procedure, and that the response was well controlled. In particular, the inspectors noted that the shift supervisor demonstrated excellent command and '

control; while not becoming overly involved in specific operations, he demonstrated thorough comprehension of overall plant conditions through the conduct of seveial short briefings with the control room operators. These briefings reviewed the existing plant conditions, and addressed target conditions and near-term activitie The licensee conducted an investigation to determine the root cause of the inadvertent reactor scram. The event occurred during the course of performing LPfiM calibration and functional checks per Operating Procedure (OP)-4406, "LPRM Calibration and Functional Checks," Revision 13, dated October 18,1996. This i activity was being directed by a member of the reactoi engineering staff (the reactor I engineer), with actions being performed by operators and instrument and controls )

(l&C) technicians. At the beginning of the procedure, the two APRM ct.annels (A ;

and D) that were supplied by the LPRM channels to be calibrated, were placed in l bypass (per step I.A.4.). These switches are on the main control board (MCB) and !

the action was performed by an operator. This action prevents test signals from j being input to the RPS while the associated LPRMs are being calibrated. A -

l subsequent procedural step (l.A.6.) performed by an l&C technician behind the MCB placed the APRM mode switches in the "Zero" position, but the restoration portion of the step which directed that these switches be placed back to the " Operate" position was missed. L ater in the calibration, the procedure (step l.A.10.) called for i a verification that APRM power was consistent with actual core thermal power, in preparation for taking the APRM channels out of bypass. However, the APRM channels both stillindicated zero power, due to the earlier mispositioning of their mode switches. The reactor engineer knew that the next procedural step took the APRM channels out of bypass, and incorrectly concluded that this action would restore normal indication and allow the required comparison to be completed. The reactor engineer then directed the operator (a licensed reactor operator) to take the APRM channels out of bypass (per step I.A.11). The operator did not notice that the APRM channels indicated zero and restored both channels to operate in rapid succession (within about one second of one another). When each affected APRM channel was placed in operate, its zero indication generated a reactor trip signal i (APRM downscale) on its respective RPS channel. Since the affected APRM channels each input to different RPS channels, this produced an actual reactor tri The f ailure of the VY operating staff to have adhered to OP-4406 steps I.A.6. and I.A.10., directly resulted in the reactor protection system actuation and reactor scram from 100 percent power at 9:10 AM on April 24,1997. This is a violation of Technical Specification 6.5, " Plant Operating Procedures." (VIO 97-04-01)

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The licensee concluded that the root causes were personnel errors in 1) work practices, and 2) communications. Specific work practice errors by the reactor engineer were failures to follow the procedure, in omission of the step to return the APRM mode switches to " Operate," and in not completing the procedural step to verify that APRM power was consistent with core thermal power prior to proceeding to the next step. The work prectice error that was attributed to the reactor operator was failure to verify correct system response after returning the first APRM to service. Such a verification would have revealed the unexpected system response (one channel of the RPS tripped) and allowed it to be resolved before plant operation was affected. The verbal communication error was that the reactor engineer did not seek resolution of what he interpreted to be a procedural conflict (the APRM power comparison that could not be completed without performing the subsequent procedural step to take the APRMs out of bypass). In addition, the licensee identified procedure inadequacy (multiple actions required to be performed within a single procedural step) and lack of knowledge of APRM operations, as contributing cause As immediate corrective action, the licensee conducted training on lessons learned from this event with alllicensed operators. In a meeting with a!I plant personnel, the expectation for procedural adherence and communication of emergent problems was stressed. Long term corrective action included review and upgrade of all reactor engineering procedures that have the potential to produce a half or full scram, and training for reactor engineering personnel on the neutron monitoring and reactor protection systems. These actions are anticipated to be completed prior to the end of 199 The inspector agreed that the cause of the scram was a combination of personnel errors. The inspector considered that a significant contributing factor was that the calibrations were being simultaneously performed on two APRM channels, with each APRM providing input to its respective RPS channel. While this is acceptable with respect to operability requirements, the operational consequences of an equipment malfunction or procedural error have the potential to be much more severe (as demonstrated by this event) than with a single channel calibration. The inspector noted that this aspect of the event, while not specifically identified as a cause in the licensee event report (LER 98-008, revision 0), will be examined as part of VY's corrective action, c. Conclusions The April 24 reactor scram occurred due to personnel error. The specific error was the failure to adhere to the surveillance test procedure OP-4406, "LPRM Calibration and Functional Check," steps 1.A.6. and I.A.10., and is a violation of Technical Specifications. Operator response to the transient was very good and, with some minor exceptions, plant response was norma . ~- - . . . .. _ - - . .

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01.2 Plant Startuo and Return to Full Power Ooeration

Inspection Sr.o_pe (71707)

i l During the pai. ad May 7-9,1997, the inspectors observed portions of the plant i startup and ret an to t;:l power operatio . Observations, Findinas, and Conclusions Following completion of the outage to repair main steam bypass valve V2-77, plant startup was commenced on May 6. The reactor mode switch was placed in the STARTUP position at 9:34 p.m. Reactor startup was commenced at 12:57 a.m., ;

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May 7, and criticality was achieved at 2:38 a.m. Following reactor heatup and '

l startup of the steam plant, the reactor mode switch was placed in the RUN position at 8:20 p.m. The main generator was synchronized to the grid at 10:08 a.m., May 1 8, and 100 percent power was achieved at 7:37 a.m., May i The inspector observed portions of the plant startup from the control roo !

Operations were deliberate and well controlled. For example, when difficulty was '

encountered with initial rod movement on one rod (a condition that occasionally i occurs due to the design of the control rod drive), actions were closely supervised i'

by the shift supervisor, and strict procedural compliance was observed. Turbine generator startup and synchronization to the grid was also observed to have been i performed deliberately and with close direction and oversigh .3 (Ocen) Unresolved item (97-04-02): high oxygen concentration in the torus air space during plant operations Inspection Scope (71707)

On May 12,1997, a weekly surveillance to measure oxygen concentration in the torus air space revealed that the concentration was greater than the four percent limit established by Technical Specification (TS) 3.7. Observations and Findinas At 12:25 a.m., the torus air space oxygen concentration was measured to be percent. This determination was made with one of the installed drywell hydrogen / oxygen monitors. A local sample, taken by a radiation protection (RP)

technician using different monitoring equipment, indicated 7.5 percent oxygen. At .

12:30 a.m., operators entered TS 3.7.A.8, which requires that an orderly shutdown be initiated immediately and that the reactor be in a cold shutdown condition within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />, if TS 3.7.A.1 through A.7 cannot be satisfied.

l Operators noted that similar indications had been observed during a weekly torus l oxygen sample that was performed during November 1996, and that the cause had

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been an air leak on the containment air monitor (CAM); this event is discussed in l

inspection report 96-200. To eliminate this possible cause, the CAM was isolated.

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The filter cover was examined and determined not to be leaking. In addition, torus l oxygen concentration remained unchanged with the CAM isolated, further indicating }

that air leakage into the sample stream was not the cause of the problem. The RP ;

technician then obtained a second grab sample from an alternate sample point in the i l

containment atmosphere dilution system. At 4:00 a.m., this sample indicated percent oxygen in the torus air spac !

At 5:30 a.m., operators had commenced reducing reactor power as required by TS ;

3.7.A.8. In accordance with 10 CFR 50.72, the NRC was notified at 6:13 a.m. that '

the plant had commenced a TS required plant shutdown (EN 32314).

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, The torus air space had been inerted on May 8, in the normal course of the plant l startup. The licensee suspected that the high oxygen concentration was the result of inadequate nitrogen purging during that operation, rather than being caused by air ;

leakage into the torus air space. The apparent reason for the inadequate purge was 1 that the procedure for inerting the drywell had been revised, since its previous use, i i to delete the option of inerting the drywell and torus in parallel (the previous preferred method of inerting vice inerting the torus and drywell individually). This change was made due to a recently identified concern that a design basis loss of- ?

coolant accident, coincident with operations to purge or inert the drywell, could overpressurize the standby gas treatment system, despite automatic system ,

isolation at the onset of the accident. This issue was discussed in inspection report l 97-03 and is the subject of an inspector follow item (97-03-01). Previously, the - l l drywell and torus were purged at the same time, and the licensee considered that !

this likely resulted in better mixing of the air and nitrogen. The licensee further considered that the close proximity of the sample point to the torus nitrogen inlet'

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- 8 inerting operation, leading operators to secure the nitrogen purge too earl Therefore, VY station management directed that inerting of the torus would be resumed in parallel with the plant shutdown, with the shutdown to be terminated when torus air space oxygen concentration was reduced to less than four percent.

l Torus inerting was commenced at 9:45 a.m. At 12:00 noon on May 12, torus air

space oxygen concentration was measured to be 1.0 percent, and torus inerting was secured at 12:30 p.m. Power reduction for the reactor shutdown was stopped at 12:40 p.m., at 94 percent power. At 2:00 p.m., the licensee exited TS 3.7.A.8, i and commenced power escalation at 2:30 p.m. The plant returned to full power l operation at 5:22 p.m. The licensee instituted daily torus oxygen sampling until

consistent oxygen concentration had demonstrated that adequate inerting had been performed, and verified that the source of oxygen had not actually been an air leak into the toru j

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The licensee initiated an event report (ER No. 97-0516) to document this event and to initiate corrective action. At the close of the inspection period, this event report 3

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6 Conclusions A weekly surveillance revealed that oxygen concentration in the torus air space was greater than allowed by Technical Specification (TS). Prompt action was taken to verify this result and to reduce oxygen concentration to within TS limits. The condition was preliminarily determined to be due to inadequate nitrogen purging during containment inerting following plant startup. While the licensee's response to the high oxygen concentration was found acceptable, the inspectors were concerned that the licensee controls were not successful in avoiding this conditio Pending further inspector review of the cause of this event, this issue is unresolved (URI 97-04-02).

01.4 Unusual Event Declared due to Indication of a Possible Seismic Event _ Insoection Scope (71707)

The inspector reviewed the events surrounding the licensee's declaration of an Unusual Event (UE) in response to a plant seismic monitor alar Observations and Findinas i

At 7:03 a.m. on May 31,1997, operators received a seismic monitor alarm. There were no other indications that a seismic event (earthquake) had occurred. The licensee declared an Unusual Event at 7:25 a.m., based on procedure AP-3125, !

" Emergency Plan Classification and Action Level Scheme," entry criteria U-5-c, ,

"Any earthquake sensed on-site as recognized by observation or detection." The states of Vermont, New Hampshire, and the Commonwealth of Massachusetts were notified, and a one-hour emergency notification (EN 32420) was made to the NRC as required by 10 CFR 50.7 l The licensee responded in accordance with operating procedure OP-3127, " Natural j Phenomena." This included visual inspection of selected plant structures for possible damage, and completion of a seismic damage indicator walkdown of plant systems. No evidence of earthquake damage was observed. Examination of data retrieved from the seismic monitor revealed that only one of the three accelerometers had detected motion. Given that no other monitoring stations had detected an earthquake, the licensee concluded that the cause of the seismic monitor alarm had been a spurious indication from a single accelerometer. The l

licensee terminated the UE at 9:35 a.m. Subsequent troubleshooting of the seismic monitor demonstrated that the suspect accelerometer had faile Conclusions l The VY staff responded appropriately to the seismic monitor alarm and the declaration of an Unusual Event was in accordance with their emergency procedures. However, the inspector considered that the procedural requirement to declare an Unusual Event based on a single indication was overly conservativ Allowance to verify that a seismic event has actually occurred prior to making an

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event determination would potentially avoid the unnecessary mobilization of state l

and federal emergency response organization h l 3 04 Operator Knowledge and Performance  ;

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04.1 Operator Performance Observationc l

l Inspection Scope (71707)  ;

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As discussed in section 01.1, the cause of the April 24 reactor scram was personnel error. During this inspection period, the inspectors noted other instances  :

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! Observations and Findinas l

During a planned shift of shutdown cooling from residual heat removal (RHR) loop A l to loop B, a licensed operator attempted to start a B-loop RHR pump while its i suction valve was still close I

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While placing the second feedwater regulating valve in service during the plant

l startup from the outage, the shift supervisor became engaged in non plant-related .

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activities in the control room that reduced his effectiveness at monitoring the I l evolutio i The pre-job brief for single rod scram testing on April 24 did not include a i

. discussion of possible problems and actions to be taken. 'Nhen a rod failed to i l scram, attention was initially focused on determining whether an error had been  ;

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made in the test equipment setup rather than on restoring the plant condition to  !

normal. Later, the shift supervisor directed that the rod be fully reinserted using the  !

manual rod control syste ! Conclusions The inspector was concerned that the number and nature of these instances were above normal, with respect to operations staff performance in recent inspection l periods. This concern warrants additional management attention to ensure that this l in not an early indication of a performance trend. These observations and concern were discussed and acknowledged by VY station managemen ;

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11. Maintenance i

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M1 Conduct of Maintenance ,

i j M 1.1 Maintenance Observations l

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! Inspection Scope (62707)  !

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The inspectors observed portions of plant maintenance activities to verify that the correct parts and tools were utilized, the applicable industry code and technical .;

specification requirements were satisfied, adequate measures were in place to ,

l ensure personnel safety and prevent damage to plant structures, systems, and  !

l components, and to ensure that equipment operability was verified upon completion l of post maintenance testin !

! Observations. Findinas. and Conclusions [

The inspector observed all or portions of the following maintenance activities:

e Disassembly and inspection of one of the scram solenoid pilot valves (SSPVs) suspected of having excessive wear, observed on April 26,199 !

SSPV malfunction is discussed in section M2.2 of this report; the inspector observed that only the suspect solenoid valve plunger showed indication of wear (black dust), and that the other solenoid valve plunger appeared as if !

new. No deficiencies were noted in the conduct of this maintenanc j e Replacement of air pressure regulators for the emergency diesel generator i service watet flow control valves, observed May 22,1997. This maintenance was performed to address the possibility that non-nuclear safety (NNS) regulator malfunction could cause the SW flow control valves L to fail shut and thereby render the EDGs inoperable; this problem is  !

discussed further in section E1.3 of this report. The NNS regulators were j replaced in-kind with units that had undergone commercial grade dedicatio !

No deficiencies were noted in the conduct of this maintenanc M1.2 S_urveillance Observations Insoection Scone (61726)

The inspectors observed portions of surveillance tests to verify proper calibration of test instrumentation, use of approved procedures, performance of work by qualified personnel, conformance to LCOs, and correct post-test system restoratio i

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i Observations, Findinas, and Conclusions  !

The inspector observed all or portions of the following surveillance tests

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Single rod scram time test for rod 06-11, observed on April 24,1997. This i testing was performed in response to the slower than expected individual rod l scram time that was observed during the April 24 reactor scram, and led to the discovery that the scram solenoid pilot valve assembly was defectiv i This material problem is discussed further in section M2.2 of this report; i performance observations from this testing are discussed in section 04.1 of this repor Main turbine minimum speed oil trip test, observed on May 8,1997. This l' test was performed during the main turbine startup in preparation for synchronizing the main generator to the grid. The test was well controlled and was completed satisfactoril i Torus-to-drywell vacuum breaker cycling, observed on May 30,1997. Along ,

with a raview of the precedure, the pre-job brief included discussion of how communications would be handled, problems that had previously occurred, ,

and actions to be taken if problems were encountered. The test was completed satisfactoril M2 Maintenance and Material Condition of Facilities and Equipment M2.1 Planned Mini-Outaae for Repair of Main Steam Bvoass Valve V2-77

. Inspection Scope (62707)

The inspector reviewed the scope of maintenance activities that were completed during the April 24 - May 7 maintenance outag l

~ Observations and Findinas l l

The principle activity that required the plant to be shut down and cool down was repair of the main steam bypass valve, V2-77. This valve had developed a body-to- !

bonnet leak soon after startup from the 1996 refueling outage, and attempts to i perform an on-line temporary leak repair had been unsuccessful; these activities were discussed in inspection report 96-11. The plan was to repair the existing valve, but a replacement valve was ready for installation, if repair proved unfeasibl '

No other major maintenance activities were originally planned to be worked, and the outage was projected to last approximately two days. However, several emergent !

- problems forced extension of the outage to May 7. The problem that most i significantly affected the schedule was an oilleak that developed on the mam transformer; this item is discussed further in section M2.3 of this report. Other emergent issues included:

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l e Scram solenoid pilot valve refurbishment / replacement; this item is discussed in section M2.2 of this report i

• Repair of a small oil leak on the "B" recirculation pump motor e Replacement of a leaking valve body seal on each the "A" and "C" main ;

steam relief valves

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r e Rerouting of several electrical cables to resolve cable separation concerns; this issue was discussed in inspection report 97-03, and is further addressed in section E1.1 of this report , Conclusions The licensee's decision to shut down for repair of V2-77 was the result of a ;

thorough review of the available repair options. Licensee preparations for this i maintenance were thorough. The outage duration was extended primarily due to *

emergent maintenance that could not have been foreseen going into the outag These issues were appropriately addressed prior to plant restar M2.2 Scram Solenoid Pilot Valve Malfunction , Inspection Scooe (62707) ,

During post-scram review of individual control rod scram times, the licensee noted :

that rod 06-11 was significantly slower that all of the other rods. The scram time from position 48 to 46 for rod 06-11 was 0.526 seconds, as opposed to the core ;

average of 0.280. The licensee initiated additional testing of rod 06-11 to I determine the cause of the slow scram tim ! Observations and Findinas

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On the afternoon of April 24, with the plant stillin HOT SHUTDOWN, single rod scram time testing was attempted on rod 06-11. However, the rod did n'at insert l when scrammed, remaining instead fully withdrawn at 48 steps. TrouNeshooting by instrument and controls (l&C) personnel identified the cause to be that the scram l solenoid pilot valve (SSPV) assembly was not venting in response to a scram signal,

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thereby preventing the hydraulic control unit (HCU) scram valves from operating to scram the rod. VY informed the NRC of the failed scram time test as required by 10 CFR 50.72 (EN 32263).

During the 1996 refueling outage, VY had replaced all SSPVs. The replacemen valves were developed and qualified for this application in a cooperative effort between VY and a valve manufacturer (Automatic Valves, or AVCO), in response to historic difficulties that had been experienced with existing SSPVs. The new valves differ from existing SSPVs in that they do not use elastomer diaphragms. They are configured such that both SSPVs for a particular HCU are contained in a common valve body, whereas the original SSPVs were two independent units. Although VY j i l l

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I is currently the only licensee that uses this dual solenoid valve unit in an SSPV !

application, these valves are used in different applications by other licensees. VY also uses these valves to operate the scram discharge volume vent and drain valves, and the main steam isolation valve Soon after startup from the 1996 refueling outage, VY noted that several of the l new SSPV units were producing a buzzing noise. VY inquired to AVCO regarding the noise, and the response was that such noise was expected with AC-powered l solenoids (60-cycle hum) and that it did not constitute a problem. Nevertheless, VY '

tracked the condition, periodically noting which units were buzzing and how loud they were buzzing (based on a qualitative scale, developed specifically for this condition). RPS surveillance testing made it possible to identify which of the two solenoids was buzzing by noting whether the noise stopped when a half scram signal was inserted. This accumulated information became significant when it was recognized that the SSPV that failed on April 24 (HCU 06-11) was one of the units that had been buzzin VY sent the failed SSPV unit to AVCO for cause determination. No prior ;

troubleshooting of the unit was attempted by VY, so that the as-failed condition '

would not be disturbed. AVCO determined that the cause of failure was that one of the solenoid plungers was bound in the energized position (pilot valve remains closed). The SSPV solenoids de-energize to scram and both solenoids pilot valves must be open for the associated rod to scram. The top of the plunger was found to )

! have a peened edge around the upper end. The peened material had caught in the ;

plunger guide and caused the plunger to stick. AVCO concluded that the cause of the plunger deformation was slight, cyclic movement of the plunger, in6Jced by the 60-cycle AC power to the solenoid, which was causing the top of the plunger to strike the plunger backseat. This condition had been the source of the buzzing noise and, over time, had produced wear and deformation of the plunger en AVCO notified the NRC that they were initiating the 10 CFR 21 process for reporting of a defective component (EN 32253).

Based on this proposed failure mechanism, VY inspected the remaining SSPVs that had been producing a buzzing noise. For all nine units inspected, the solenoid that had been identified to be buzzing (through l&C's earlier informal monitoring) was found to have a worn plunger. The wear was evidenced by the presence of black dust. The black dust had also been present in the SSPV that was sent to AVCO, and had been identified by them to be the same material as the plunger (400-series stainless steel). By unaided visual inspection, none of the worn plungers showed evidence of deformation or peening. However, the degree of wear (that is, the amount of black dust) was found to correlate roughly with the level of noise that the solenoid had been making. The nine associated solenoids that had not been i buzzing showed no indication of wear.

l The worn plungers were replaced and the SSPVs were tested to verify that the buzzing noise had been eliminated. In one case, the noise persisted after plunger replacement, so the entire SSPV unit was replaced. The replaced components were sent to AVCO for additional evaluation. Single rod scram time testing was l

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pe'rformed on all rods associated with the SSPV refurbishment / replacement, with satisfactory result !

l l Although the root cause of failure was still under investigation by AVCO, V !

L . concluded.that the inspections of the nine SSPV units had demonstrated that the  !

l buzzing noise was a conclusive indicator of incipient solenoid failure. To support l

! continued operation pending completion of the root cause determination, VY {

instituted a weekly inspection of all SSPVs by I&C personnel, and shiftly checks for abnormal noise, to be performed by operations personnel. A basis for maintaining operation, BMO 97-19, was generated to document this approach, i Conclusions  !

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L The conclusion that solenoid buzzing could be used as an indicator of incipient  !

failure was adequately supported by the SSPV inspection results. Increased- j monitoring of the SSPVs for noise was an appropriate interim corrective actio !

Resolution of.this issue will be tracked by the licensee's BMO, and will be  !

progressed by the inspectors as a matter of routine inspectio ;

' M2.3 Main Station Transformer Oil Leak Following the plant shutdown 'on April 24, plant workers identified an oil leak on i one of the gasketed manways to the main transformer (T-1).' A number of repair  ;

alternatives were considered, but VY concluded that gasket replacement was the i most prudent resolution. During the process of manway removal and gasket i L replacement, additional inspections of transformer internals were conducted. These i ( inspections identified additional repair work which required ' partial oil draindown and an increase in the original transformer work scope. The transformer problems and repair work had no direct nuclear safety impact. However, main transformer  :

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reliability and availability does affect balance of plant related transients and challenges to the reactor protection system. It was the inspector's understanding that the transformer repairs were prudently authorized, but not essential to continued safe and reliable operation of the generating unit. Licensee staff inspection of the transformer following it being placed in service on May 8,1997 identified no discrepancie .- Enaineerina  !

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[ E1 Conduct of Engineering [

L 1 E Emeroency Diesel Generator Potential Common Mode Failure .j On May 21,1997, the control room operators notified the NRC in accordance with 10 CFR 50.72 (EN 32370) of a condition outside their design basis which

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i potentially could have rendered both emergency diesel generators (EDGs)

l inoperable. The EDG service water (SW) flow control valves (FW-104-28A and B)

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- are air-operated and supplied via non-nuclear safety related (NNS) 100/35 psig pressure regulators in the NNS instrument air system. The failure of the NNS i

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pressure regulators could cause the FCV-104-28A and B valves to failin the closed position, whv,h would isolate service water cooling flow through the EDG lubricating oil and jacket water cooling heat exchanger The discovery of this EDG system design vulnerability was made by the NRC Architect Engineering Team inspection staff. A more detailed examination and summary of this finding will be documented in their inspection report. The resident inspectors verified that, upon recognition of tnis design vulnerability, the VY staff made an operability assessment of each EDG and properly notified the NRC per 10 CFR 50.72 of this design issue. As discussed in section M1.1 of this report, the inspector witnessed and verified prompt replacement of the NNS pressure regulators with similar commercially dedicated regulators. An inspector followup item will track this issue pending issuance of the inspection report and final characterization of the inspection finding. (IFl 97-04-03)

E1.2 480 Volt AC System inspection Scope (37551)

The inspector reviewed the licensee's protection and coordination for the rotating uninterruptible power supply (RUPS), and the 480 Volt Bus 9 (supply bus) and MCC 89A (load bus) to assess the coordination of the RUPS with its associated buse Observations and Findinas The inspector reviewed calculation VYC-1087, Attachment B, page 36,480 Volt-SWGR Bus 8 and 9 Breaker Settings, Rev 1, dated July 8,1992. This document provided the protection and coordination time-current characteristics for Bus 8 and 9 related protective devices. The inspector observed that the information for the RUPS ac feeder protective devices included the conductor sizes for the motor feeders. The inspector obse:ved that the ac motor feeder included a 350 MCM conductor with a transition to an AWG No.1 conductor local to the RUPS. The inspector questioned the apparent lack of overcurrent protection for the AWG N conductors on the RUPS ac input power circuit. In response, the licensee produced an internal schematic for the RUPS, drawing 502011266, Sheet 1, Rev.2, dated December 30,1996, which also indicated AWG No.1 conductors located between the internal RUPS ac breaker and the ac motor. The licensee's drawing confirmed the RUPS ac breaker was rated 150 amps consistent with the coordination curv The inspector confirmed that the 1990 National Electrical Code, Table 310-16, permitted an AWG No.1 conductor with a 90 C rating to continuously carry 150 amps. The inspector also confirmed the nameplate fullload current of the ac motor was 105 amp The inspector observed that the RUPS was not the largest load on Bus 8 or 9. Both buses have a 250-HP control rod drive water pump and a 125 HP reactor building cooling water pump. In addition, Bus 9 also has a 250-HP fire water pum Licensee Event Report 50-271/92-018 addressed a previous problem that had resulted in a transient low voltage when starting the fire pump with reduced bus

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voltage. In the past, this had resulted in a swap-over of the RUPS from its ac ;

source to dc power. The inspector reviewed an evaluation, Yankee Nuclear Services Division (YNSD) had performed in response to VY Service Request PM N . That evaluation, contained in file VYE 89/92, Bus 9 Voltage Analysis for ,

RUPS Evaluation, dated December 4,1992, concluded, based on a computer model l

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(DAPPER), that under reduced bus voltage of 460 Vac, starting the fire pump motor could result in the observed transfer of the RUPS from ac to de supply power. The inspector was informed that this evaluation formed the basis for a niodification to l the RUPS trip circuit performed under JO920068. The inspector reviewed the i results of that evaluation and questioned the input data and results. In response, ,

the YNSD agreed that there appeared to be errors in the model used for the i evaluation. However, these apparent errors would result in an even lower voltage than the YNSD model had calculated. The inspector was informed YNSD would issue an event report to document the discrepancy and initiate appropriate corrective action to re-evaluate the model used for the fire pump starting evaluatio The details of JO920068 were not available during this inspection. These items will ]

remain open pending NRC review of the revised modeling of the fire pump starting l

and retrieval of JO920068 from the historical records (IFl 50-271/97-04-06). j

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The inspector requested information on the Bus 9 load and breaker settings to j confirm the coordination of the Bus 9 incoming breaker with the largest loads on the '

bus. The inspector reviewed selected coordination sheets from drawing B-191305, 480 V SWGR Bus 8 and 9, CAPTOR Project VY480SI, Rev. O, dated July 8,1992, !

and proposed changes, dated August 9,1996. The inspector confirmed that sufficient coordination existed for the feeder breakers to Bus 9 and all the load breakers. The inspector confirmed that the existing and future settings contained in i

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the coordination package for the Bus 9 incoming and tie breakers provided sufficient protection for both the station service transformer and the 480 Volt bus. The inspector also confirmed the fire pump motor (FPM) coordinated with the bus feeder breakers during starting of the FP The licensee provided breaker information for the RUPS ac load side connection which was based on the original static inverter. The licensee indicated they had i planned an update for the coordination study for these breakers during 1997 for consistenc c. Conclusions The inspector concluded the coordination curve for the ac supply side of the RUPS should have clarified the apparent lack of protection for the AWG No.1 transition cable to the ac motor. This was considered a weakness in the calculation. The l

inspector concluded the coordination of the 480 Volt Bus 9 feeder breaker with the l RUPS and the 250 HP motors were acceptable, l

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E1.3 Rotatina Uninterruotible DC Power Sucolv Insoection Scoce The de power supply for the rotating uninterruptible power supplies (RUPS) consists

of the batteries and a de machine. The batteries had been the de supply for the l l original static UPS. The de machine acts as a battery charger when driven from the l ac motor and a de motor when it is driving the ac generator upon loss of the ac l supply. The inspector reviewed the basis for the selection, sizing and test {

acceptance criteria for the batteries associated with the RUP )

l Observations and Findinas The inspector reviewed calculation VYC-1630, Battery Sizing Calculation for 400 l VDC RUPS Batteries, dated February 26,1997, to assess the design requirements for the RUPS batteries. The inspector found that the sizing calculation was based j on a minimum permissible battery terminal voltage of 360 Volts, derived a duty '

cycle from a previous ECCS Integrated Automatic Initiation Test, and included appropriate margins for battery aging and minimum temperature. The calculation estimated the maximum current seen by the battery would be 75 amps during l

stroking of valve V10-27A. In addition, the calculation held that current for five i minutes. The inspector found the calculation acceptabl l The inspector reviewed the test procedures for the safety-related batteries associated with the RUPS batteries-1 A and 18. The inspector reviewed the results of the last performance test performed on battery RUPS-1 A on September 5,1993 (Procedure OP 4209, Rev. 6). The results of the discharge test indicated the

battery had a capacity of 110% of the manufacturer's ratin The inspector reviewed the latest service test results obtained on October 10,

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1996, for battery RUPS-1B (Procedure OP4219, Rev. 6). The inspector found that the acceptance criteria only required the demonstration that the battery was capable of supplying the UPS with the power necessary for the UPS to supply its ac loads

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during the integrated ECCS test. No minimum battery voltage was specified and the data indicated the voltage at the battery dropped to 385 Volts after 173 seconds. The inspector confirmed the longest stroke time permitted for MOV V10-27B by the RHR System Surveillance Test, OP 4124.01, Rev.46, dated l April 24,1997, was 44.45 seconds. The inspector found that the post-modification test that was performed following installation of the RUPS indicated the RUPS low voltage dc trip was set at 365 +/-2 Volts. Therefore, the inspector found the test acceptabl Conclusions The inspector concluded the RUPS batteries were adequately sized for their present application and had additional margin beyond their design basis.

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E2 Engineering Support of Facilities and Equipment {r E Post-Modification Test of the Vernon Tie 5 kV Cable 1 l Insoection Scooe i

The inspectors reviewed the maintenance and testing performed on the 5.0 kV l cable that forms part of the power supply from the Vernon hydroelectric station to assess its reliabilit i

! Observations and Findinas The inspectors found that the feed had been upgraded in 1993 by installing a new l buried 15 kV line from Vernon to the VY site (EDCR 90-412.) This EDCR was ;

originally installed to upgrade the feed to support 10 CFR 50.63, the Station ;

Blackout Rule. A new transformer was also installed at the VY end of the line to !

interface with the VY 4160 volt bus. A new section of 5 kV cable was installed !

from the transformer to a manhole where it was spliced to a section of the existing !

5 kV cable into the plan l The inspectors observed that the installation included high-direct-voltage testing ;

(Hi-pot) of the new cables and an insulation resistance (IR) test of the existing 5 kV i cable section. The inspectors reviewed the test results of the Hi-pot testing that - I was performed in June 1993 and noted that the new 15 kV and 5 kV cables )'

appeared to have successfully withstood a de proof test at 65 kV and 35 kV respectivel The inspector questioned why the existing cable was also not subjected to a de Hi-pot. The existing cable section had been installed in underground duct banks, subject to moisture, and normally energized, but unloaded, for most of its installed 3 life. This type of installation has historically been responsible for most of the i medium voltage cable failures reported in the electrical power industry. The .

licensee indicated hi-pot testing for the existing cable section was not required by i engineering design change request (EDCR)89-407 and the insulation resistance test l showed good IR values. The inspector reviewed the post-modification test data and confirmed the IR testing performed on August 20,1993, produced excellent results with the minimum value recorded of 375 Megohms. These readings included both the new and old sections of the 5 kV cable and the splice joining them togethe The licensee indicated that when apparent lightning damage was found on another section of the old abandoned Vernon tie 5 kV cable, the old, still-used section of cable that was the transition into the plant was given a reduced voltage (10 kV) hi-pot test. The inspector reviewed the results of hi-pot tests that were performed on July 18,1995, and concluded, based on a review of IEEE Std. 400-1991, Guide for Making High-Direct-Voltage Tests on Power Cables in the Field, that the step voltage method was superior to the original high voltage proof test performed in l

1993. The inspector also confirmed the leakage currents at the 10 kV test voltage j were equal to or less than 1 microamp.

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The inspectors reviewed the background for determining the reduced test voltage !

and compared it to other guides, recommendations and practices used throughout ,

the electric industry. The inspector noted that there is no universal standard in test ;

voltages for cables installed for more than five years. Test voltages for 5 kV cables range from 10 to 25 kV and often refer the user to the manufacturer for their recommendation. The inspector confirmed the licensee had contacted various manufacturers, other utilities and industry experts during a previous review for i testing associated with the startup transformer cables in 1993. Based on the industry practices and the review of the 1995 hi-pot test results, the inspector i found the test voltage used was acceptabl ;

i Conclusions

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The inspectors concluded the installation and followup testing of the Vernon tie was j acceptable based on industry test practices ano the Vernon tie cable test results, '

which showed good insulation resistance and adequate dielectric strengt E7 Quality Assurance in Engineering Activities The licensee's Design Basis Documentation (DBD) and Improved Technical Specifications (ITS) projects have the potential for identifying inconsistencies between the design, licensing, and operating bases of plant structures, systems, and components. Such inconsistencies will be documented in this section of th report and tracked to resolution as inspection follow item E RHR Service Water Flow Reauirements l

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On May 6,1997, the control room operators notified the NRC in accordance with 10 CFR 50.72 (EN 32285) of a potentially degraded /unanalyzed condition involving the residual heat removal service water (RHRSW) system. Examination of the l UFSAR accident analyses assumptions by the NRC Architect Engineering Team !

identified that the minimum RHRSW flow through the RHR heat exchangers (2,700 i gpm) may not be achieved because the existing flow instrument uncertainty of plus j or minus 200 gpm. Station Operating Procedure (OP)-2124 instructs operators to limit RHRSW system flow to a maximum of 2,700 gpm. Consequently, the actual flow may exceed the established limit (potentially adversely impacting heat exchanger design flow limits) or fall short of the prescribed cooling flow (potentially compromising torus heat removal and containment response assumptions).

l The inspector verified the interim actions taken by the VY staff to limit continued re,ctor plant operations to Connecticut River water temperatures of 70 degrees F and below which will ensure the facility remains within established ultimate heat sink heat removal capacity assumptions. This issue will be tracked via an l Inspection Follow item pending final characterization of this inspection finding and issuance of the inspection report. (IFl 97-04-04)

E7.2 individual Plant Examination of External Events (IPEEE) Review issues (37551)

The licensee's IPEEE review project has the potential for identifying inconsistencies i between the plant design and its capability to cope with certain external events, l

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The issues identified via this project will be documented in this section of the report and tracked to resolution as inspection follow items, as appropriate. The VY staff is currently targeting completion of their IPEEE by the end of 199 Failure of Various Non-Seismic Pioina Could Affect Safety Related Eauioment On May 20,1997, the control room operators notified the NRC in accordance with 10 CFR 50.72 (EN 32362) of a condition outside the plant's design basis, involving the postulated failure of non-seismic piping which could adversely impact safety related equipment. Specifically, the failure of service water supply lines in the '

HVAC room, sers.ce water lines to non-safety related components in the reactor building (recirculation motor-generator set lube oil coolers), and fire protection suppression water system piping in the reactor core isolation cooling (RCIC) room have all been postulated to result in flooding of the safety related components in the immediate and/or adjacent areas. These postulated failures and their consequences were not previously identified in VY's 1988 Flooding Stud The inspector reviewed the licensee's immediate systems' operability assessments which concluded that the identified piping, although not seismic category 1, was of sufficient design and strength to withstand design basis earthquake dynamic loading. In addition, established operator actions for dealing with internal plant flooding and formal Emergency Operating Procedures provide appropriate guidance for dealing with these types of postulated events. The inspector found this initial operability assessment satisfactory and the interim compensatory actions appropriate. Pending final resolution, this design concern will be tracked as an laspector Followup item. (IFl 97-04-05)

E8 Miscellaneous Engineering issues E8.1 (Closed) Follow-uo item 50-271/97-02-07: offsite electrical power sources Inspection Scope (37551)

By letter dated February 25,1997, the NRC staff requested additional information pertaining to the VY offsite power system design. The NRC staff was completing a review of older operating plants' offsite power systems based upon the lessons learned from the Maine Yankee Independent Safety Assessment. The review was focused on the adequacy of the delayed offsite power circuits as required by General Design Criteria (GDC) 17, and in particular, the reliance upon main and unit auxiliary transformers to backfeed power to the onsite distribution syste VY responded to the request for additional information by letter dated March 26, 1997. The March 26,1997 letter established that no analysis had been cornpleted to demonstrate that the main transformer backfeed delayed offsite power source could be established in sufficient time to prevent fuel design limits and design conditions of the reactor coolant pressure boundary from being exceeded. In lieu of this analysis, the licensee relied upon the Vernon Tie (a second delayed offsite power circuit) to restore electrical power (within ten minutes via switches in the control room) until the main transformer backfeed could be made available (in approximately six hours). The March 26,1997 letter also established that VY

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N l 19 considered the Vernon Tie as acceptable for compliance with both GDC 17, as a delayed access source and 10 CFR 50.63, " Station Blackout Rule" as an alternate ,

alternating current (AC) power sourc .

Following review of VY's March 26 response, the NRC conducted a telephone

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discussion with the VY staff followed by a letter dated April 17,1997 summarizing i I the NRC staff's understanding of the offsite power systems and their conclusion  !

that the Vernon Tie cannot serve as one of the GDC 17 offsite power sources and I as an alternate AC power source. The VY staff attempted to clarify their licensing and design basis of the offsite power systems via VY letter dated April 24,199 ; Observations and Findinas Via conference calls between the NRC staff and VY management on April 25,  !

1997, the NRC staff informed VY that GDC 17 was satisfied via the 345 kv auto- '

transformer (for immediate access power) and the Vernon Tie (for delayed access power). Further, that the Vernon Tie could not be credited for satisfying 10 CFR l 50.63. In addition, the NRC staff considered this issue not to be a unit restart impediment, provided VY submitted their plans within 30 days for complying with l 10 CFR 50.63. Via letters dated April 29,1997 and May 1,1997, the licensee l formalized their commitments for complying with 10 CFR 50.63 and the NRC staff l l

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acknowledged the acceptability of VY's schedule to achieving full compliance, respectively.

l By subsequent letter dated May 29,1997, VY docketed their plans to implement

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j modifications, with supporting analysis and licensing bases, to establish the main transformer back feed capability as the GDC 17 delayed access power circuit. In addition, VY docketed their plans to initiate the appropriate licensing actions to support the re approval of the Vernon Tie as the 10 CFR 50.63 Station Blackout alternate AC power sourc Conclusions l

l The licensee satisfies 10 CFR Part 50, Appendix A, GDC 17, " Electric Power j Systems' and has committed to comply with 10 CFR 50.63 prior to start-up from l

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the 1998 refuel outage. This inspection follow-up item is closed. NRC staff review of VY's proposed modifications and licensing changes will be examined during a future inspection period.

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E8.2 (Closed) LER 50-271/97-007: inadvertent primary containment isolation system i

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actuation due to a spurious spike on a reactor building vent radiation monitor, dateri May 21,1997. VY staff response was appropriate for this spurious radiation monitor electronic noise spike and subsequent ventilation systems automatic isolation and initiation. Proper verification measures were initiated to confirm radiological conditions did not cause the event and that automatic system responses

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were as designed. The control room staff appropriately notified the NRC in accordance with 10 CFR 50.72 (reference Event No. 32192, dated April 21,197 i

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E8.3 (Closed) LER 50-271/97-008: plant scram due to procedural non-compliance and failure to perform self-verification during nuclear instrumentation calibration, dated May 23,1997. This event is discussed in section 01.1 of this repor E8.4 (Closed) LER 50-271/97-009: lack of specificity in plant Technical Specifications {

results in operation of the plant service water systems which was inconsistent with '

prescribed limiting conditions for operation and testi~g requirements, dated May 21, 1997. The inspector noted that the root cause of th s issue could not be determined because of the length of time this TS reg Jirement had been in effect (since initial licensing in 1971). The interim and more restrictive administrative limits placed upon service water subsystem operation were determined appropriate by the inspector. The VY staff plans to remedy this TS discrepancy upon NRC staff review and approval of their improved TSs, targeted for 1998. Also, reference inspection report 97-02, section E7.1 and inspector follow item 97-02-0 i E8.5 (Closed) LER 50-271/97-010: individual control rod drive scram time greater than ,

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normal due to manufacturing defect in scram solenoid pilot head assembiy,69d May 21,1997. This event is discussed in section M2.2 of this repor ;

l E8.6 (Ocen) Violation 50-271/96-09-06. inadeauate batterv service test accentme I criteria i Inspection Scope (92701)

I Inspection report 50-271/96-09 discussed a problem with test control for the main station batteries. The licensee had failed to incorporate any appropriate acceptance criteria for the battery service test. The criteria that was provided had no basis in any design document and failed to consider the minimum battery terminal voltage l used to determine the acceptable operation of safety-related de equipment. The inspector reviewed the licensee's corrective action in response to Violation 96-09-0 ) Observations and Findinas in their response letter, BVY 96-161, dated December 20,1996, the licensee indicated four corrective actions would be taken to avoid further violations. The licensee indicated that the first three items (update the calculation, perform a consistency review of the battery test procedures and define ownership of design basis calculations) would be completed by April 30,1997, and the remaining item (update procedure OP 4215) would be completed by June 30,1997. These corrective actions were further defined by the licensee in their Event Report (ER) No. 7 96-0748, t

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The inspector confirmed that calculation VYC-298, Battery Sizing Calculation for

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Vermont Yankee Station Batteries A-1 and B-1 was revised (Rev.10) on April 22,1997, and calculation VYC-1349,125 Volt DC Voltage Drop, was revised (Rev.1) on April 30,1997. The inspector also confirmed copies of the calculations were forwarded to the electrical maintenance engineer at VY. At the time of this i inspection, the Main Station Battery Test Procedure, OP 4215, had not yet been i updated to be consistent with the new calculations, j

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The inspector confirmed that the Electrical /l&C Design Group established a Calculation Tracking System in response to the NOV. The controlling list of calculations was issued on April 7,1997. The tracking system lists the calculations by number, responsible engineers, affected calculations and procedures

! and pending revisions to the base calculation. The inspector noted that even though calculation VYC-1349 was listed in the cover memorandum, the tracking system failed to identify a pending revision against the calculation. The inspector was later provided a copy of the June 1,1997, issue of the tracking system and noted it correctly indicated calculation VYC-1349 had been revise The inspector noted ER 96-0748 did not limit this corrective action to just Electrical /l&C Design Engineering but it was assigned to Design Engineering in general. The inspector also noted the Plant Operating Review Committee (PORC)

review of the ER specifically indicated all Design Engineering departments should

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evaluate if a similar tracking system is necessary. As of the close of this inspection, it did not appear that any other discipline had initiated an evaluation of a

.similar calculation tracking system. The inspector did confirm that Vermont Yankee Design Engineering Procedure (VYDEP) 15, Calculations, had been revised (Rev.2)

on March 31,1997, to emphasize the relationship of calculations to procedures and other document The inspectors confirmed that the licensee had performed a consistency review of the surveillance procedures associated with the batteries defined in the technical specifications. The licensee issued an interoffice memorandum, dated May 20,1997, which documented the review of the service test procedures for batteries AS-2, the ECCS batteries and the main station batteries against their design basis calculations. The licensee indicated that all the associated battery calculations were revised in 1997 and the procedures are being revised to include the new load profile The inspector noted the absence of the RUPS batteries from the May 20th memorandum. Tne !!censee explained that the RUPS batteries were purposefully not included in the memorandum because they are tested with the actualloads during their surveillance test and are not tested to a calculated load profile. The ,

inspector found this acceptabl c. Conclusions

The inspector concluded the licensee had not completed all the corrective actions in response to the notice of violation. The licensee had updated the battery sizing and j voltage drop calculations. These calculations had been transmitted to the site in l response to the new calculation ownership process. The inspectors noted that the j licensee is continuing to review these calculations.

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S1 Conduct of Security and Safeguards Activities l  ! Inspection Scope

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Determine whether the security program, as implemented, met the licensee's :

commitments in the NRC-approved security plan (the Plan) and NRC regulatory l requirements. The security program was inspected during the period of  ;

l May 27-30,1997. Areas inspected included: management support and audits; l effectiveness of management controls; alarm stations and communications; training and qualification; and the vehicle barrier system, Observations and Findinas i

Management support was evident based on the effective implementation of the !

security program as documented in this report. The Security Manager's position in ,

the organizational structure and reporting chain permits management's awareness l of issues and concerns, management controls for identifying, resolving, and

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preventing programmatic problems were effective, and audits were thorough and in-depth. Alarm station operators were knowledgeable of their duties and i responsibilities and security training was being performed in accordance with the -

NRC-approved training and qualification (T&O) pla Based on the inspection of the land vehicle barriers and discussions with plan j engineering and security management, the inspector determined that the licensee's i provisions for land vehicle control measures satisfy regulatory requirements and licensee commitments. After review of UFSAR and Section 5.3.2 of the Plan, i

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entitled " Vehicle Searches," the inspector determined by observing security force members performing vehicle searches, discussing with security supervision, and 1 l reviewing applicable procedures and records that vehicles were being properly l searched prior to permitting protected area access as required in the Plan and -

applicable procedure Conclusions The inspector determined that the licensee was conducting its security and safeguards activities in a manner that protected public health and safety and that the program, as implemented, met the licensee's commitments and NRC requirement S2 Status of Security Facilities and Equipment S2.1 Alarm Stations and Communications l InsDection Scope Determine whether the Central Alarm Station (CAS) and Secondary Alarm Station r (SAS) are

(1) equipped with appropriate alarm, surveillance and communication capability, (2) continuously manned by operators, and (3) use independent and l

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! diverse systems so that no single act can remove the capability of detecting a threat l and calling for assistance, or otherwise responding to the threat, as required by l NRC regulation b. Observations and Findinos Observations of CAS and SAS operations verified that the alarm stations were equipped with the appropriate alarm, surveillance, and communication capabilitie Interviews with CAS and SAS operators found them knowledgeable of their duties and responsibilities. The inspector also verified through observation and interviews that the CAS and SAS operators were not required to engage in activities that would interfere with the assessment and response functions, and that the licensee had exercised communications methods with the locallaw enforcement agencies as committed to in the Pla l

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c. Conclusion j l

The alarm stations and communications met the licensee's Plan commitments and 1 NRC requirement l S5 Security and Safeguards Staff Training and Qualification l

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a. Inspection Scone i Determine whether members of the security organization are trained and qualified to perform each assigned security-related job task or duty in accordance with the T&Q Pla b. Observations and Findinos On May 29,1997, the inspector observed tactical response training. The training !

involved the proper use of cover and concealment, tactical movement, weapons ;

manipulation, and shooting under stress. Based on observations, toe training was

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properly controlled, safety was stressed at all times, and the instructors were knowledgeable of the subject matter. Additionally, the inspector interviewed a number of SFMs to determine if they possessed the requisite knowledge and ability to carry out their assigned duties, c. Conclusions The inspector determined that training had been conducted in accordance with the T&Q Plan. Based on responses to the inspector's questions, the training provided by the security training staff was found to be effectiv . _ _

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S6 Security Organization and Administration Insoection Scoce Conduct a review of the level of management support for the licensee's physical security progra Observations and Findin_qs The inspector reviewed various program enhancements made since the last program inspection, which was conducted in July 1996. These enhancements included the procurement of tactical response training aids and ongoing range improvement The inspector reviewed the Security Manager's position in the organizational structure and reporting chain. The Security Manager reports to the Technical Services Superintendent, who reports to the Plant Manager, who reports directly to the Vice-President of Operations. Additionally, the inspector noted that the access authorization and fitness-for-duty programs, being safeguards related, report directly to the Security Manage Conclusions Management support for the physical security program was determined to be !

effective. No problems with the organizational structure that would be detrimental to the effective implementation of the security and safeguards programs were note )

i S7 Quality Assurance in Security and Safeguards Activities j S7.1 Effectiveness of Manaaement Controts Inspection Scoce  !

Determine if the licensee has controls for identifying, resolving, and preventing I programmatic problem Observations and Findinas The inspector reviewed the licensee controls for identifying, resolv'ing, and preventing security program problems. These controls included the implementation of a departmental self-assessment program, which includes the performance of post assessments by security supervision and the performance of the NRC-required annual quality assurance (QA) audits. The licensee also utilizes industry data, such as violations of regulatory requirements identified by the NRC at other facilities, as l criteria for self-assessment. The inspector reviewed documentation applicable to the performance of the self-assessment program and noted that 51 self-assessments were conducted in 1996 and, as of this inspection, 26 self-assessments were performed during 1997.

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l performed per month by security shift supervision. The inspector determined, based '

on a review of the safeguards event logs, self-assessments, and post assessments i that personnel performance errors were minima i

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The inspector concluded that controls were effectively implemented to prevent and !

resolve potential weaknesse S7.2 Audits inspection Scope I

l Review the licensee's Quality Assurance (QA) report of the NRC-required security program audit to determine if the licensee's commitments as contained in the Plan were being satisfie Observations and Findinas I The inspector reviewed the 1996 QA audit of the security program, conducted October 21-24,1996, (Audit No. VY-96-04) and the 1997 combined QA audit of I the fitness-for-duty (FFD)/ access authorization (AA) programs, conducted l February 12-23,1997, (Audit No. VY-97-19). The audits were found to have been i conducted in accordance with the Plan and FFD rule. To enhance the effectiveness of the FFD/AA audit, the audit team included one independent technical specialis The security audit report identified no findings. The combined FFD/AA audit identified four findings and six recommendations. The findings involved general employee training weaknesses concerning information on the effects of prescription 1 and over-the-counter drugs on job performance and chemical test results, two documentation issues involving AA records, and the accuracy of the random drug !

testing pool. The audit results had been disseminated to the appropriate levels of l management. The inspector determined, based on discussions with security management and FFD/AA supervision, that the responses to the audit have not been finalized as of the inspection. Those findings will be reviewed during a subsequent inspectio Conclusions The review concluded that the audits were comprehensive in scope and depth, that the findings were appropriately distributed, and that the audit program was being properly administere I

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26 l l S8 Miscellaneous Security and Safety issues l

S8.1 Vehicle Barrier System (VBS)

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Backaround l On August 1,1994, the Commission amended 10 CFR Part 73, " Physical Protection of Plants and Materials," to modify the design basis threat for radiological sabotage to include the use of a land vehicle by adversaries for transporting personnel and their hand carried equipment to the proximity of vital areas and to include the use of a land vehicle bomb. The amendments require reactor licensees to install vehicle control measures, including vehicle barrier systems (VBSs), to protect against the ,

malevolent use of a land vehicle. Regulatory Guide 5.68 and NUREG/CR-6190 were !

issued in August 1994 to provide guidance acceptable to the NRC by which the i licensees could meet the requirements of the amended regulations, j

A February 23,1996, letter from the licensee to the NRC forwarded Revision 27 to its physical security plan that detailed the actions implemented to meet the requirements of 10 CFR 73.55 (c)(7),(8), and (9) and the design goals of the

" Design Basis Land Vehicle" and " Design Basis Land Vehicle Bomb." A NRC l

i June 19,1996, letter advised the licensee that the changes submitted had been )'

reviewed and were determined to be consistent with the provisions of 10 CFR 50.54(p) and were acceptable for inclusion in the NRC-approved security pla This inspection, conducted in accordance with NRC Inspection Manual Temporary Instruction 2515/132, " Malevolent Use of Vehicles at Nuclear Power Plants," dated January 18,1996, assessed the implementation of the licensee's vehicle control measures, including vehicle barrier systems, to determine if they were commensurate with regulatory requirements and the licensee's physical security pla Insoection Scoce The inspector reviewed documentation that described the VBS and physically inspected the as-built VBS to verify it was consistent with the licensee's summary description submitted to the NR Observations and Findinas l The inspector's walkdown of the VBS and review of the VBS summary description disclosed that the as-built VBS was consistent with the summary description and met or_ exceeded the specifications in NUREG/CR-619 Conclusion The inspector determined that there were no discrepancies in the as-built VBS or the VBS summary descriptio I i

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! 27 S8.2 Bomb Blast Analysis Inspection Scope The inspector reviewed the licensee's documentation of the bomb blast analysis and verified actual standoff distances provided by the as-built VB ' Observations and Findinas The inspector's review of the licensee's documentation of the bomb blast analysis determined that it was consistent with the summary description submitted to the NRC. The inspector also verified that the actual standoff distances provided by their as-built VBS were consistent with the minimum standoff distances calculated using NUREG/CR-6190. The standoff distances were verified by review of scaled drawings and actual field measurement Conclusion No discrepancies were noted in the documentation of bomb blast analysis or actual standoff distances provided by the as-built VB S8.3 Procedural Controls Inspection Scope The inspector reviewed applicable procedures to ensure that they had been revised to include the VB ) Observations and Findinas The inspector reviewed the licensee's procedures for VBS access control measures, surveillance and compensatory measures. The procedures contained effective controls to provide passage through the VBS, provide adequate surveillance and inspection of the VBS, and provide adequate compensation for any degradation of !

the VB i Conclusions l The inspector's review of the procedures applicable to the VBS disclosed no discrepancie V. Manaaement Meetinas Exit Meeting Summary

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! The inspectors met with licensee representatives periodically throughout the l inspection and following the conclusion of the inspection on June 10,1997. At !

i that time, the purpose and scope of the inspection were reviewed, and the 4 l preliminary findings were presented. The licensee acknowledged the preliminary inspection finding :

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, Management Meeting Summary l On April 30,1997, representatives of VY, General Electric, and Yankee Atomic Electric Company met with the NRC staff in Rockville, MD, to discuss current and future fuel cycle operation at VY. A summary of this meeting was provided by VY i via correspondence to the NRC, BVY 97-69, dated May 22,199 On May 15,1997, VY managers met with the NRC Region I staff in King of Prussia, f PA, to discuss performance improvements in the engineering area. Materials that !

were presented during the meeting are attached to this repor Review of Updated Final Safety Analysis Report (UFSAR)

A recent discovery of a licensee operating its facility in a manner contrary to the I UFSAR description highlighted the need for a special focused review that compares l plant practices, procedures, and parameters to the UFSAR description. While performing the inspections discussed in this report, the inspectors reviewed the :

applicable portions of the UFSAR that related to the areas inspected. Discrepancies l that were noted were documented in the applicable section of the above repor t Since the UFSAR does not specifically include security program requirements, the ;

inspectors compared licensee activities to the NRC-approved physical security plan, ,

which is the applicable document. While performing the inspection discussed in this l report, the inspector reviewed Section 5.3.2 of the Plan, Revision 27 dated ,

February 23,1996, titled, " Vehicle Searches." The inspector determined, by I observing security force members performing vehicle searches, discussions with :

security supervision and reviews of applicable procedures and records, that vehicles are being properly searched prior to permitting protected area access as required in the Plan and applicable procedure !

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l lNSPECTION PROCEDURES USED l

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! 62707 Maintenance Observations  :

l- 61726 Surveillance Observations j 71750 Plant Support Activities j 71707 Plant Operations  ;

37551 On-Site Engineering '

92700 - On-Site Follow Up of Written Reports of Non-routine Events

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81700 Physical Security Program for Power Reactors -

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Ti 2515/132 Malevolent Use of Vehicles at Nuclear Power Plants  ;

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! ITEMS OPENED, CLOSED, AND DISCUSSED .

OPEN  :

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- VIO 97-04-01 Violation of Technical Specification 6.5, " Plant Operating Procedures" URI 97-04-02 Torus oxygen concentration outside TS limits  !

IFl 97-04-03 Potential for loss of EDG SW flow due to SW flow control valve air pressure regulator failure l l IFl 97-04-04 RHR service water flow requirements ~

! IFl 97-04-05 Failure of various non-seismic piping could affect safety related l equipment  !

IFl-97-04-06 Electrical circuit model to support evaluation of voltage drop during :

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start of the fire pump l t i i

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IFl 97-02-07 Offsite electrical power sources l LER 97-007 Inadvertent primary containtnent isolation system actuation, May 21, 1997 LER 97-008 Plant scram, May 23,1997  ;

,. LER 97-009 Lack of specificity in plant TS i j LER 97-010 Individual control rod drive scram time greater than normal DISCUSSED l

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URI 97-03-02 Operability assessments for the identified cable separation  !

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1 PARTIAL LIST OF PERSONS CONTACTED G. Maret, Plant Manager S. Jefferson, Assistant to Plant Manager F. Helin, Tech. Services Superintendent E. Lindamood, Director of Engineering K. Bronson, Operations Manager M. Watson, l&C Manager M. Desilets, Radiation Protection Manager R. Gerdus, Chemistry Manager G. Morgan, Security Manager C. Nichols, Electrical and Controls Maintenance Manager J. Moriarty, Security Operations Specialist L. Pitts, Security Technical Assistant W. Peterson, Quality Assurance (QA) Manager, Yankee Atomic Energy Company (YAEC) ,

A. Wonderlick, QA Engineer, YAEC F. Harper, Project Manager, The Wackenhut Corporation (TWC)

E. Wright, Security Operations Supervisor, TWC G. Sherer, Security Project Coordinator, TWC J. Jasinski Security Training Supervisor, TWC P. Corbett, Project Engineering Manager, VY B. Donovan, Electrical Maintenance Engineer, VY q

' D. Maidrand, Electrical (DC) System Engineer, VY  !

D. Philips, Manager, Electrical and l&C Maintenance Engineering, VY D. Jannary, Manager, Electric and l&C Design Engineer, YNSD l P. Johnson, Sr. Electrical Engineer, YNSD l R. Cox, Electrical Engineer, YNSD

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R. Moschella, Electrical Engineer, YNSD J R. Vibert, Electrical Engineer, YNSD

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LIST OF ACRONYMS USED VY Vermont Yankee NRR Office of Nuclear Reactor Regulations NRC Nuclear Regulatory Commission TS Technical Specifications EDG emergency diesel generator  ;

LER Licensee Event Report j RHR residual heat removal l HVAC heating, ventilation, and air conditioning l DDFP diesel driven fire pump DBD design basis documentation ,

HELB high energy line break  !

EDCR engineering design change request {'

URI unresolved item IFl inspector follow item I CS core spray I SFM security force members l QA quality assurance

the Plan NRC-approved physical security plan PA protected area i T&Q training and qualification IDS intrusion detection systems

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CAS central alarm system SAS secondary alarm system UFSAR Updated Final Safety Analysis Report l CCTV closed circuit television )

VBS vehicle barrier system l l

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ENCLOSURE 3

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, VERMONT YANKEE ENGINEERING UPDATE l NRC Region i Meeting, May 15,1997 l

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Vermont Yankee Engineering Update

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I XRC Region 1 Meeting May 15,1997 i

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l Agenda l Introduction l

l II. Overview of Engineering Organization III. System Engineering IV. Design Engineering Initiatives

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