ML20149G868

Notice of Violation from Insp on 970324-0522.Violation Noted:Licensee Failed to Esatblish Measures to Assure That Significant Condition Adverse to Quality Was Promptly Identified & Corrected & C/A Taken to Preclude Repetition

ML20149G868
Person / Time
Site:	Sequoyah
Issue date:	07/10/1997
From:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
To:
Shared Package
ML20149G854	List: ML20149G852 ML20149G868
References
50-327-97-05, 50-327-97-5, 50-328-97-05, 50-328-97-5, NUDOCS 9707240106
Download: ML20149G868 (54)

Text

i NOTICE OF VIOLATION Tennessee Valley Authority Docket Nos. 50 327 and 50-328 Sequoyah Units 1 & 2 License Nos. DPR-77 and DPR 79 EA No. 97 232 ,

During an NRC inspection conducted from March 24 through May 22, 1997, violations of NRC- requirements were identified. In accordance with the '

" General Statement of Policy and Procedure for NRC Enforcement Actions,"

NUREG 1600, the violations are listed below:

A. 10 CFR 50, Ap)endix B, Criterion XVI, requires, in part, that measures shall be esta)lished to assure that conditions adverse to quality, such as failures, malfunctions, deficiencies, deviations, defective material and equipment, and nonconformances, are promptly identified and corrected. In the case of significant conditions adverse to cuality, +

the measures shall assure that the cause of the condition is cetermined i and corrective action taken to preclude repetition.

Contrary to the above, the licensee failed to establish measures to assure that a significant condition adverse to quality was promptly identified and corrected and corrective action was taken to preclude repetition. Specifically, j

1. On March 23 and March 24, 1997, during an evolution to drain the i pressurizer to 25% level, the licensee failed to identify the l inability to accurately monitor and control reactor coolant system (RCS) inventory, a significant condition adverse to 1 quality. Specifically, several operations personnel observed a malfunction of the cold calibrated pressurizer level instrumentation and failed to promptly identify that the  !

pressurizer cold calibration level indication was malfunctioning and take corrective action. This unidentified malfunction 3 contributed to the inadvertent draining of the pressurizer to less i than 0% cold calibration level.

2. On September 11, 1995, and on April 24, 1996, the cold calibration reference legs for Unit 1 and Unit 2, respectively, were backfilled after rapid depressurization of the RCS, and the licensee failed to take measures to ensure that RCS inventory could be properly monitored and controlled in that the cause of the reference leg voiding was not identified and corrective actions to preclude repetition of the reference leg voiding were not taken. (01013)

Enclosure 1 9707240106 970710 PDR ADOCK 05000327 G PDR

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a Notice of Violation 2 B. Technical S3ecification 6.8.1.a requires, in part, that procedures shall be establisled, implemented, and maintained covering the activities recommended in Appendix A of Reaulatory Guide 1.33, Revision 2. February '

19/8, " Quality Assurance Progran, Nguirements (Operation)." A3pendix A of Regulatory Guide 1.33 Section 2, includes procedures for "_og Entries, Record Retention, and Review Procedures."

SSP-12.1, Conduct of Operations, Revision 16, Section 3.8.3 C. 3.  !

requires, in part, that relevant information reflecting static or {

changing plant conditions shall be recorded in at least une narrative log. Section 3.8.5 D. requires, in part, that late entries shall be annotated by alacing the current time and the words " LATE ENTRY",

followed by t1e time the entry should have been made, and then the entry.

Contrary to the above, on March 23 and 24, 1997, relevant information  !

reflecting static or changing plant conditions was not recorded in at '

least one narrative log, in that: (1) on March 23, a Ur.it 1 RCS drain down was initiated at approximately 11:00 p.m. and was not recorded: (2) on March 24, a Unit 1 RCS drain down was terminated at approximately i 2:00 a.m. and was not recorded; and (3) on March 24, 1997, a Unit 1 RCS  !

dnin down was logged at 8:25 a.m. as being initiated at aaproximately )

7:15 a.m. and terminated at a33ror.imately 7:45 a.m., and t1e log entry I was not annotated as a " LATE ffRY." (01023)

These violations represent a Severity Level III problem (Supplement I).  ;

Pursuant to the provisions of 10 CFR 2.201, Tennessee Valley Authority (Licensee) is required to submit a written statement or explanation to the U. S. Nuclear Regulatory Commission. ATTN: Document Control Desk, Washington, ,

D. C. 20555 with a copy to the Regional Administrator, Region II, and a co3y I to the NRC Resident Inspector at the Sequoyah facility, within 30 days of t1e l date of the letter transmitting this Notice of Violation (Notice). This reply !

should be clearly marked as a " Reply to Notice of Violation" and should l include: (1) the reason for the violation, or, if contested, the basis for l disputing the violation (2) the corrective steps that have been taken and the results achieved (3) the corrective steps that will be taken to avoid further i violations, and (4) the date when full compliance will be achieved. Your i respor.se may reference or include previously docketed correspondence, if the  !

correspondence adequately addresses the required res3onse. If an adecuate i reply is not received within the time specified in t1is Notice, an orcer or i Demand for Information may be issued as to why the license should not be j modified, suspended, or revoked, or why such other action as may be 3 roper 1 should not be taken. Where good cause is shown, consideration will 3e given  !

to extending the response time.  ;

Under the authority of Section 182 of the Act, 42 U.S.C. 2232, this response shall be submitted under oath or affirmation. i l

Enclosure 1 i

.. _ ._ . . . _ _ . . _ . _ _ _ _ _ . _ _ - . _ _ _ - . _ . . . _ ..___.-.._._._.___.m._.

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l Notice of Violation 3 i

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Because your res>onse will be placed in the NRC Public Document Room (PDR), to i the extent possiale, it should not include any personal privacy, proprietary, i or safeguards information so that it can be placed in the PDR without

! redaction. If personal privacy or-proprietary information is'necessary to provide an acceptable response, then please provide a bracketed copy of your

-response that identifies the information that should be protected and a redacted copy of your response that deletes such information. If you~ request L withholding of such material, you must s)ecifically identify the prtions of ,

i.; your response that you seek to have with1 eld and provide in detail the bases j for your claim of withholding (e.g.. . explain why the disclosure of information l 4

will create an unwarranted invasion of personal privacy or provide the information required by 10 CFR 2.790(b) to support a request for withholding

!~ confidential commercial or financial information). If safeguards information is necessary to provide an acceptable response, please provide the level of

protection described in 10 CFR 73.21.

l l l Dated at Atlanta, Georgia ,

this 10th day of July 1997  !

f Enclosure 1

I 1

NRC 03EN 3REDECIS10NA_ l i

EN 01 CEMENT CONFERENCE l

SEQUOYA- NUC_ EAR PLAN ~~

JUNE 27, 1997 Enclosure 2

a s

W j PREDECISIONAL ENFORCEMENT CONFERENCE AGENDA  ;

l SEQUOYAH I

a l JUNE 27,1997, AT 10:30 A.M.

I NRC REGION ll OFFICE, ATLANTA, GEORGIA l

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1. OPENING REMARKS AND INTRODUCTIONS L. Reyes, Regional Administrator

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! II. NRC ENI'ORCEMENT POLICY

B. Uryc, Director i Enforcement and investigation Coordination Staff ,

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! 111.

SUMMARY

OF THE ISSUES

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L. Reyes, Regional Administrator i IV. STATEMENT OF CONCERNS / APPARENT VIOLATION

{

J. Johnson, Director, Division of Reactor Projects j

i V. LICENSEE PRESENTATION 1

1 VI. BREAK / NRC CAUCUS l Vll. NRC FOLLOWUP QUESTIONS Vill. CLOSING REMARKS L. Reyes, Regional Administrator 9

1 4

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ISSUES TO BE DISCUSSED A. 10 CFR 50, Appendix B, Criterion XVI, requires, in part, that measures shall be established to assure that conditions adverse to quality, such as failures, malfunctions, deficiencies, defective material and equipment, and non-conformances, are promptly identified and corrected, in the case of significant conditions adverse to quality, the measures shall assure that the cause of the condition is determined and corrective action taken to preclude repetition.

Specifically, as of March 24,1997, the licensee failed to:

1) Correct the slope of the pressurizer cold calibration levelinstrument reference leg to the criteria of a slope of % inch per foot of tubing run as listed on Mechanical instruments & Controls Drawing 47W600-24, Revision 13;

2) Perform adequate root cause evaluations for the multiple backfills of the pressurizer reference legs between 1980 and 1997;

3) Effectively implement the corrective actions from ths May 1993 Incident investigation Event Report for the 1993 inadvertent drain down, including:

• Ensuring that operators use multiple independent pressurizer level channels during drain down evolutions, including the use of the reactor vessel level indication system (RVLIS),

• Ensuring that operators use a pressurizer level correction curve during drain down evolutions,

• Implementing positive inventory controls during drain down evolutions.

NOTE: THE APPARENT VIOLATIONS DISCUSSED IN THIS PREDECISIONAL ENFORCEMENT CONFERENCE ARE SUBJECT TO FURTHER REVIEW AND ARE SUBJECT TO CHANGE PRIOR TO ANY RESULTING ENFORCEMENT DECISION.

_ . _ _ _ -. . _.. ._ _ - _ _ _ _ _ _ _ _ . __mm m B. Technical Specification 6.8.1.a requires, in part, that procedures shall be .

established, implemented, and mairdained covering the activities ,

recommended in Appendix A of Regulatory Guide 1.33, Revision 2, February I 1978, " Quality Assurance Program Requirements (Operations)." Appendix A of Regulatory Guide 1.33, Section 1, includes procedures for " Authorities and Responsibilities for Safe Operation and Shutdown.

SSP-12.1, Conduct of Operations, Revision 16, Section 2.1.A.1. states that

. Operations personnel on each shift must "Be knowledgeable of those aspects of plant status relevant to their responsibilities." Section 3.1.4 B.

4 and C. state respectively that the shift manager (SM) responsibilities include "on-shift management and oversight of all Plant Group activities to ensure i safe and reliable plant operation...," and to " maintain a broad perspective of operation conditions affecting the safety of the plant as a matter of highest

, priority at all times." Section 3.17.2 B. states, "The SM, as the senior manager and resource manager, is in complete charge of shift activities.

Section 3.1.5 F. lists one responsibility of the unit separvisor as " Coordinate p the activities of the unit operators with other Operatians and plant personnel to achieve safe, reliable, and efficient operation cf the unit.

SSP-12.1, Conduct of Operations, Revision 16, Section 3.2.7, Responses to indications, states, in part, "When an instrument failure is suspected the following actions shall be taken to determine the true condition and to implement compensatory actions: A. Stabilize or limit plant conditions until all aspects of the instrument failure are understood and compensatory actions taken."

SSP-12.1, Conduct of Operations, Revision 16, Section 3.8.3 C. 3. requires, in part, that relevant information reflecting static or changing plant conditions shall be recorded in at least one narrative log. Section 3.8.5 D.

requires, in part, that late entries shall be annotated by placing the' current time and the words " LATE ENTRY", followed by the time the entry should have been made, and then the entry.

1) On March 24,1997, the on-coming and off-going SMs were not knowledgeable of those aspects of plant status relevant to their responsibilities, and did not maintain on-shift management and oversight of all Plant Group activities to ensure safe arrd reliable plant operation, and did not maintain a broad perspective of operation conditions affecting the safety of the plant as a matter of highest NOTE: THE APPARENT VIOLATIONS DISCUSSED IN THIS PREDECISIONAL ENFORCEMENT CONFERENCE ARE SUBJECT TO FURTHER REVIEW AND ARE SUBJECT TO CHANGE PRIOR TO ANY RESULTING ENFORCEMENT DECISION.

priority 'at all times, and was not in complete charge of shift activities, 4- in that the SMs were not aware that a reactor coolant drain down was initiated for Unit 1 at approximately 6:58 a.m. on March 24,1997.

The unit supervisor did not coordinate the activities of the unit operators with other Operations and plant personnel to achieve safe,  !

reliable, and efficient operation of the unit, when he failed to notify

. the shift manager of the restart of the drain down evolution.

2) On March 24,1997, the oncoming shift manager did not stabilize or-limit plant conditions when he suspected a failure or possible problem with the pressurizer level indicators. I l

3) On March 23,1997, relevant information reflecting static or changing plant conditions was not recorded in at least one narrative log, in that 1 on March 23, a Unit 1 reactor coolant system drain down was initiated at approximately 11:00 p.m. and was not recorded.

4) On March 24,1997, relevant information reflecting static or changing plant conditions was not recorded in at least one narrative log, in that on March 24, a Unit 1 reactor coolant system drain down was terminated at approximately 2:00 a.m. and was not recorded.

5) On March 24,1997, relevant information reflecting static or changing plant conditions was not recorded in at least one narrative log, in that a Unit 1 drain down was re-initiated at approximately 6:58 a.m., and was terminated at approximately 8:30 a.m., and was incorrectly entered into the logs at 8:25 a.m. as having been initiated at 7:15 a.m. and terminated at 7:45 a.m.

G) On March 24,1997, a late entry to the logs was not annotated by placing the current time and the words " LATE ENTRY", iollowed by the time the entry should have been made, and then the entry;in that a reactor coolant system drain down was logged at 8:25 a.m. as being initiated at approximately 7:15 a.m. and terminated at aporoximately 7:45 a.m., and the log entry was not annotated as a

" LATE ENTRY."

NOTE: THE APPARENT VIOLATIONS DISCUSSED IN THIS PREDECISIONAL ENFORCEMENT CONFERENCE ARE SUBJECT TO FURTHER REVIEW AND ARE SUBJECT TO CHANGE PRIOR TO ANY RESULTING ENFORCEMENT DECISION.

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'9 Tennessee Valley Authority Sec uoyaa Nuc. ear P;. ant

. TVA/XRC Meeting Predecisiona: Enforcemerr: Conference Pressurizer Leve Reduc: ion June 27, :.997 h

(

Enclosure 3

du NRC/TVA Meeting Predecisional Enforcement Conference Pressurizer Level Reduction June 27,1997 Agenda Introduction O. J. Zeringue i

Reference Leg Design and Operation History R. K. Gladney Event Evolution W. R. Lagergren Operations Crew Performance W. R. Lagergren Corrective Actions H. H. Butterworth Management Initiatives J. T. Herron Conclusions O. J. Zeringue i 9e9'

Sequoya:a Nuclear P:. ant 4

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Introduction .

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i Sequoyaa Nuc. ear Plant j Introc uction t

J Close Examination of Event and Associated Instrumentation Conclusion of Review

- Loss of Reference Leg Attributed to Rapid Depressurization Method- -

- Inadequate Operator Performance Primary Wealmess

. - Corrective Actions for 1993 Pressurizer Event were Reasonable and l Consistent with General Industry Practice .

Measures Taken to Strengthen Operator Understanding of Expectations and to Enhance Controls on Plant Evolutions Measures Taken to Increase Management Oversight of Plant Activities in Noncritical as Well as Critical Functions Broad Management Initiatives Underway to Evaluate Effectiveness of Past Corrective Actions

- Review of 1985 - 1988 Nuclear Plant Performance Programs

- Review of 1993 Restart Programs

- Review of Corrective Action Program Database from 1988 to 1997

- Review of selected operational events and reactor trips 2

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i Secuoya: 1 Nue: ear P:. air:

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i Reference Leg Design and 1

Operation History f

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Sequoyaa Nuc ear P . ant Reference Leg Design anc. Oaeration History Basic Reference Leg Design and Operation

- Cold cal instrument operates with an open reference leg

- Condensate pot at top of reference leg keeps the reference leg filled

- Loss of reference leg can occur by leakage, loss of condensate pot function, or gas liberation following rapid depressurization that carries liquid with it (champagne effect)

- Small loss rates caused by leakage can generally be replenished by the condensate pot with no significant loss of the reference leg column

- Large loss rates caused by rapid depressurization cannot be replenished immediately by the condensate pot 4

Sequoya a Nuc. ear Plant Reference Leg Design and Operation History Basic Reference Leg Design and Operation (cont.)

- Condensate pots are nonfunctional if a steam bubble does not exist in the pressurizer or if a condensate dam is formed in the

. sense line

- Loss of reference leg caused by rapid depressurization in solid-water operation cannot be recovered until the reference leg is backfilled 5

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Sequoyaa Nuclear Plant-Reference Leg Design and Operation History Historical Information - Sense Line Slope and Bow

- In 1988, instrument sense lines servicing safety-related instruments were walked down to verify that the original construction specification of 1/8"/ foot slope on horizontal runs was satisfied

- Sense lines that did not meet this requirement were either evaluated by Engineering for acceptability or repaired-

- The sense line bow discovered during the investigation of this event was documented during these 1988 walkdowns

- The bow was evaluated in 1988 as acceptable because loss of the reference leg for the safety-related pressure transmitter would not occur until system pressure was below operating span

- Decision to not fix the cold cal transmitter sense line bow was based on lack of safety significance but was a bad decision

- The investigation of the 1997 event found that the sense line bow did not contribute to the reference leg loss 7

Decision :n 1988 to leave bow in line was, however, narrow in focus and line has been repaired after the 1997 event

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L Sec uoya 1 N ac.. ear P ant Reference Leg Design anc. Operation History Historical Information - Root Valve Configuration

- In 1985, Engineering issued a design change to replace the pressurizer upper tap root valve for 1-LT-68-339 (hot cal level). The existing valve was an angle valve and was suspected of creating a condensate dam that was preventing steam from migrating to the condensate pot resulting in loss of reference leg

- The design replaced the angle valve with a straight valve that was not capable of collecting condensed steam  ;

- Instrument performance shows the modification was successful at eliminating backfills at power

- This validates the original theory that condensate damming in the  !

angle valves was causing loss of reference leg during power operation

- In 1988, a DCN was prepared to replace upper tap root valves on the  !

remaining channels. A bad decision was made to not implement this DCN

- The remaining angle valves will be~ replaced; schedule is being 3 developed

Sec uoya l Nuc. ear Plant Reference Leg Design and Operation History Historical Information - Depressurization Method

- Method of RCS depressurization changed in 1995 from a slow steam bubble collapse to a more rapid depressurization while ,

operating in a solid water condition Rapid depressurization during solid water operation causes liberation of hydrogen gas that carries liquid with it (champagne effect)

- The champagne effect causes a loss of reference leg regardless of sense line slope, bow, or root valve configuration .

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Sec uoyaduclear P . ant Reference leg Design anc. O;3eration History Historical Information - 1993 Loss of Reference Leg

- Caused by extended leakage with no steam bubble to refill

- Comprehensive corrective actions proceduralized; focused on high risk region, ~20% to mid-loop Noncoincident eduction and draindown -

Positive inventory controls

' Redundant instrumentation for operation outside normal pressurizer level range (LLG, ULMS, pre-Mansell, etc.)

Hot / cold calibration correlation curve Level indication cross comparisons Training accomplished on procedure changes

- Heightened controls while draining to mid-loop consistent with industry practices

- Suspected leaking valve replaced - loss of fill occurrences considered within expected performince io

Sequoyal Nuc_ ear Plant Reference Leg Design anc Operation History Historical Information - 1993 Accumulation of Nitrogen in ,

-Reactor Vessel

- Use of RVLIS evaluated as useful but recognized often out-of-service for maintenance t In 1997 RVLIS taken out-of-service for maintenance while draining in region above RVLIS indication Historical Infonnation - Post 1995 Experience

- Modified 0-GO-7 procedure for pressurizer fill and accelerated depressurization Modeled after enhanced industry outage practices GO-13 procedure not affected by this change

- Modified procedure successfully implemented in 1995 and 1996 Reference leg loss recognized and addressed by refill

- In 1997, operators failed to recognize reference leg loss after i, depressurization (level instrument discrepancies)

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Secuoyan Nuclear Plant

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Event Evolution  ;

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Sec uoyaa Nuc. ear Plant Event Evo..ution

Background

Unit 1 Shut Down for Cycle 8 Refueling Outage

- Operations outage organization headed by Outage Shift Manager (SRO)

Second outage for this management structure Schedule for outage developed and approved by onshift SROs; reviewed and approved by Operations Superintendent and Operations Manager Shift Managers' duties and responsibilities briefed prior to outage

- Outage scope presented to licensed operators prior to outage

- Licensed and nonlicensed operators went on four-group, twelve-hour shift the week prior to start of outage 13

Operations Outage Organization UIC8 Refueling Outage Operations Superintendent Operations Shift Manager (SRO)

-1Jhirnate requntsildidy

- Natificatioits 1

-SED

- Not kuulved in outage routine task Operations ShiD U2 Jr Manager Supe.<isor Outage (SRO)

(SRO)

Operations Operations Unit I ,

PMT Outage work Control Supervisor Center US Ccordinator Coordinator

.(SRO) (SRO)

(SRO) (SRO)

- Sip on outage work i UOs 14

Sec uoyal Nuclear P:. ant Event Evo..ution Background (cont.)

- Pressurizer level instrumentation part ofinitial qualification and requalification training

- Just-In-Time Training for RCS inventory reduction presented earlier in week Expectations of volume and level change covered Focus on RCS drain from pressurizer using outage specific instrumentation Training targeted at three control room crews expected to be onshift at the time of the evolution

- Crews received classroom training that covered "Mid-loop Operation" and Diablo Canyon event

- Saturday evening and Sunday day shiR crews received simulator training on taking RCS solid and draining to 60% pressurizer level

- Sunday night shift crew received simulator training starting at 25% pressurizer level and draining below that point

- No simulator training provided for pressurizer level changes in the normal operating range of 60% and 25%-

15

_____m______ __ -_.__________ ____ _ ____

Sec uoyah Nuclear Plant Event Evolution Background (cont.)

- Prerequisite actions for inventory reduction to detension head ensured Onsite and offsite power source available (switchyard protected)

Both charging pumps available with makeup capability from RWST One safety injection pump available ,

Both residual heat removal pumps available Four steam generators f'illed, do not take credit afler RCS depressurized Additionally, four cold leg accumulators filled at 100 pounds

- Adequate defense-in-depth for inventory recovery capability and loss of RHR contingency ee 16

_ .___ _ _ _ _ . = _ _ _ _ __ _ _ _ _ _ _ _ _ _ _ _ _

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Sec uoya l Nuclear Plant Event Evo.ution Background (cont.)

Unit Entered Mode 5 and RCS Taken Solid

- RCS pressure at 350 psig with two reactor coolant pumps in service

- Third refueling outage in which pressurizer inventory reduction methods were similar

- Pressurizer Drain to 25% Actual Level Performed Using 0-GO-7, " Shutdown From Hot Standby To Cold Shutdown"

- Four level instruments available Three protection set (hot cals)

One open reference leg (cold cal)

- Just-In-Time Training discussed availability of these instruments 17

Sec uoya 1 Nuc . ear Plant Event Evo_ution Background (cont.)

t Pressurizer Drain Below 25% and Subsequent RCS Drain Would Be Performed Using 0-GO-13, " Reactor Coolant System Drain and Fill Operations"

- Recurrence control actions included as a result of a 1993 inventory reduction event Noncoincident eduction and draindown '

Positive inventory controls Redundant instrumentation for operation outside normal pressurizer level range (LLG, ULMS, pre-Mansell, etc.)  !

Hot / cold calibration correlation curve Level indication cross comparisons Training accomplished on procedure changes  !

- Two additional level instruments required to be used to drain the  !

RCS (not designed to operate with RCS pressurized)  :

~~

Mansell level monitor 18 Liquid level gauge

REACTOR COOLANT SYSTEM LEVEL INDICATIONS FOR DRAINING AND FILLING S/G 764'-0* TOP OF MANSELL MONITOR (FIR $f O*;0 IN 199$)

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W Sec uoyaa Nuclear Plant Event Evo..ution Sequence of Events Previous Week Just-In-Time Training Conducted GL 88-17 Training Conducted

' March 22.1997 1330 LT-068-321 (Cold Cal Level) Checked for Calibration

- Good correlation hot and cold cal instruments

- Two RCPs in service, RCS at 350 psig, pressurizer bubble March 23,1997 0237 - Started Fill to Take RCS Water Solid 0955 - Pressurizer Solid, Two RCPs In Service at 350 psig

- Good correlation hot and cold cal instruments during level increase t 1755 - Stopped No. 4 RCP, No. 2 RUP In Service at 350 psig 20 Water solid

4 Sec uoyah Nuc.. ear Plant Event Evo..ution ,

Sequence of Events (cont.)

2230 - Prejob Briefing Held Prior to Inventory Reduction Evolution i 2257 - Stopped No. 2 RCP, Started RCS Depressurization

- 2302 RCS pressure <200 psig

- Started decreasing pressurizer level March 24.1997 0025 - Pressurizer Cold Calibration On Scale 0038 - Pressurizer Hot Cal On Scale First opportunity to notice indication was wrong .

0150 - Stopped Pressurizer Inventory Reduction to Support Diesel i Generator Surveillance Test (Cold Cal at 56%, Hot Cal At 25%)' .

- Hot cal protection channels must be >l7% to support surveillance 0630 - Cold Cal at 56%, Hot Cal at 25%, RVLIS at 102% :n l t

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1 Sequoyal Nuc . ear P ant Event Evolution Pressurizer Level Pressurizer Level (elevation) Expected Actual Ilot Cal Cold Cal Ilot Cal Cold Cal  ;

737' 2" 100 % 60 % ~99% ~94%

(Top ofIIot Cal) 721' 1" 25 % 22 % ~25% ~56%

719' 15 % 18 % ~15% ~51 %

716'3" 4% 12 % ~4 % ~40%

708' 2" Offscale - low Offscale - low Offseale - low ~ 38%*

(Minimurn level reached)

. Cold cal indication will not decrease afler level decreased below lower tap 22

Sec uoyaa Nuclear Plant.

Event Evolution Sequence of Events (cont.).

At ~ 0710 - Pressurizer Inventory Reduction Was Resumed 0711 and 0712 - Two Alarms Came In (Letdown Isolation and Pressurizer Low Level)

' At ~ 0735 - Day Shift US and U'O Assumed Shift and Noted Cold Cal at 44% and Hot Cal at 0%

At ~ 0745 - Operator Noted That Cold Cal Stopped Decreasing (38%),

Inventory Reduction Was Terminated - Pressurizer Level ~ Two Feet Above Bottom of Pressurizer At ~~ 0750 - Operators Started Increasing Charging At ~ 0815 - Pressurizer Hot Cal Came On Scale 23

Sec uoyaa Nuc. ear Plant Event Evo..ution Sequence of Events (cont.)

0816 - Charging Low Flow Alarm Cleared 0825 - Two Log Entries Made Documenting Start of Pressurizer Inventory Reduction and When Problem Noted At ~ 0840 - Pressurizer Hot Cal Level 25%

At ~ 1500 - Cold Cal Level Instrument Reference Leg Backfilled, Hot Cal / Cold Cal Levels Were in Proper Agreement -

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Operations Crew Performance r

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Sec uoya 1 Nuclear Plant Operations Crew Performance The Night Shift Crew Did Not Perform to Expectations

- Unit Supervisor (US) did not perform adequate prejob briefing

- Unit Operator (UO) did not perform an inventory balance on 4 transferring liquids UO did not recognize abnormal /off-normal plant indication using diverse and redun' dant information (cold / hot cal instrumentation, letdown isolation alarm, and low pressurizer level alarm)

- The shift crew questioned instrumentation differences but incorrectly concluded that there was no problem US/UO did not follow plant procedures pertaining to logbook entries

- Outage SM did not exercise good oversight ofinventory reduction

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Corrective Actions Corrective Actions Already Taken

- Reinforced management expectations of Operations personnel Standdown meetings were held with Operations personnel to review management expectations and review the event In addition, the Plant Manager also held a meeting with the Shift Managers to discuss his expectations for perfonnance -

- Surveyed industry for inventory reduction information Several similar design PWRs were contacted to gather information related to inventory reduction techniques Range of controls found, but most had no special controls for operation '

with level in normal operating range 29 .

-- ~ - . _ _ - _ _ - _ _ _ _ _ _ _ _ _ _ _ - - _ _ _ _ _ _ _ _ _ - _ _ - _ _ - _ _ _ _ _ _ _ _ _ _ _

4 Sec uoya 1 Nuc.. ear P . ant Corrective Actions Corrective Actions Already Taken (cont.)

- Enhanced General Operating Procedure Clarified the use of pressurizer level instruments Required the use of positive inventory control Installation of the Mansell level gauge Backfill of the cold cal channel before lowering pressurizer level

- Enhanced Licensed Operator Training Review of the principles, use, and expected response of the pressurizer level instruments Review of the 1997 inventory reduction event

- Appropriate constructive discipline for involved personnel 30

Sequoyaa Nuc.. ear P ant Corrective Actions Additional Corrective Actions

- Communication of specific expectations with Operations personnel Develop specific expectations for Operations personnel and meet with each individual to ensure their understanding and acknowledgm'ent

- Improve crew interaction and performance Evaluate individual performance attributes Strengthen / balance crew composition Return onshin personnel to a common crew rotation schedule Develop and use crew-specific performance indicators to monitor performance

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31

Sec uoya1 Xuclear P: ant Corrective Actions Additional Corrective Actions (cont.)

- Further Operations self-assessment Focus on specific problem areas such as logkeeping, prejob briefings,  ;

and conservative decision making i Expand to include extended tours with Assistant Unit Operators and control room personnel ,

Expand participation by including additional senior management and line management  ;

Expand emphasis on backshifts and weekends

- Conduct an independent assessment of the Operations department using selected peers from San Onofre, Palo Verde, and South Texas Project

- Conduct p.eriodic assessments of operator knowledge in fundamental principles and feed back the results to training l 32 i

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Management Initiatives t i

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M Sec uoyaa Nuc . ear P . ant Management Initiatives .

Examples ofIncreased Management Monitoring of Activities

- Plant trip hazards

- Surveillance instructions with ESF potential

- LCOs less than 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />

- Risk significant actions per Probabilistic Safety Assessment Management assigned to evolutions Contingency plans Additional controls Focused on Key Return to Service Processes to Preclude Future Events .

- Status control

- PMT process

- Surveillance Program

- Sensitive activities (includes pre / post-job briefs)

- Procedure adherence 34

'N Sequoya1 Nuclear P ant Management Initiatives Expand Plan of Day Meeting

- Enhance daily evaluation of plant performance / status Daily Management Review Committee Meeting

- Senior management cognizance ofidentified problems Other Process Controls to be Reviewed / Improved

- Just-In-Time Training

- Prejob briefings Special training Special management oversight Worker feedback Crew implementation of positive inventory controls

- Conduct of operations adherence

-- Procedure change process affecting equipment / plant operation

- Equipment performance monitoring process 33

I Sec uoyaa Nuclear P; ant Management Initiatives t

Reinforced Expectation for Conservative Decision Making

- Management unknowingly conditioned the operating crews to treat the initial pressurizer level reduction to 25% as a noncritical evolution i

,a 36

Sec uoyaa Nuclear Plant Management Initiatives Additional Management Initiatives to Preclude Events

- Review of 28 areas identified in 1985 - 1988 Sequoyah Nuclear Plant Performance Programs Review is continuing in six areas To date, review indicates no operational impacts

- Review of 1993 restart programs to be conducted

- The Corrective Action Program database (1988 to 1997) is being reviewed for operational events, reactivity management issues, hold order problems, PMT problems, and configuration problems.

Ninety-eight (98) corrective action documents were identified and are being reviewed Adequacy of root cause evaluations ,

Whether corrective actions address root cause determinations

. Whether corrective actions have generic impact Negative performance trends in above areas 37 '

Sec uoyal Nuc. ear P . ant-Management Initiatives Additional Management Initiatives to Preclude Events (cont.)

- Review of four most recent reactor trips and two operational events being conducted Analysis complete Conclusions and recommendations under management' review Plant Material Condition Initiatives Previously Described to NRC on Schedule 38 i

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Sequoyal Nuclear Plant Conc.usions t Broad Event Evaluation

- Technical review ofinstrumentation system

- Crew performance and conduct of operations

- Evaluation of training effectiveness

- Prejob briefing content

- Procedure review / revisions process

- Management involvement and reinforcement -

- Equipment performance monitoring Comprehensive Review of Past Corrective Actions to Assess Effectiveness ,

- Review of 1985 - 1988 Nuclear Plant Performance Program

- Review of 1993 Restart Program Review of Corrective Action Program Database from 1988 to 1997

- Review of Selected Operational Events and Reactor Trips.

40

-_____.__m.____.-___ __m. _..._____m__ .__________m-__________ __ _ _ _ _____-__. _.___-_____ _. __u.__ _

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Sec uoyal Nuc.. ear Plant Conc .usions TechnicalIssues Associated with Reference Leg Design / Installation Did Not Cause Event - Bow, Slope, Angle

~

Valves Management Established Reasonable Expectations and Controls .

Following 1993 Event Which Were Consistent With General Industry Practices

- Noncoincident eduction and draindown

- Positive inventory controls

- Redundant instrumentation for operation outside normal pressurizer .

level range (LLG, ULMS, pre-Mansell, etc.)

- Hot / cold calibration correlation curve

- Level indication cross comparisons

- Training accomplished on procedure changes

- Replaced drain valves t a

41 +

Sequoyaa Nuclear Plant Conc..usions t

Pressurizer Level Indication Inaccuracy Identified by Oncoming "

Crew Level Decrease Terminated with Over 1-1/2 Feet Water .

Remaining in Pressurizer Event Had No Safety Consequences - Pressurizer Was Not Emptied  ;

l 42 l

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I Sequoyal Nuc.. ear P ant Conc..usions Progression to Loss of RHR Not Credible

- Thirteen hours to drain to mid-loop condition

- Loss of reference leg for cold cal indicator resulted in constant (nondecreasing) indication despite continuing draindown - thirteen -

hours of monitoring with no indicator movement coincident with draindown not credible

- Outage sequenced activities for day shift would trigger draindown progress checks I

- Defense-in-depth contingencies available for loss of RCS inventory and loss of RHR OfTsite and onsite power Two charging pumps One SI pump Full RWST level (300,000 gal.)

o Four steam generators filled Four cold leg accumulators filled

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- No Potential Safety Significance 43

TVA 6 Distribution w/encls:

PUBLIC LJCallan, EDO HThompson, DEDR EJordan DEDE NDudley, OEDO LChandler,- OGC JGoldberg, OGC RZimmerman, NRR EJulian, SECY BKeeling, CA Enforcement Coordinators RI RIII, RIV JLieberman, OE OE:EA File (BSummers) (2 letterhead)

TReis. OE EHayden, OPA GCaputo OI DRos: \E00 HBell, OIG FHebdon, NRR RHernan, NRR CEvans, RII' Buryc, RII JJohnson, RII JJaudon, RII MLesser, RII (IFS Action Required)

SSparks, RII KClark, RII RTrojanowski, RII LWatson, RII NRC Resident Inspector U. S. Nuclear Regulatory Commission 2600 Igou Ferry Soddy Daisy, TN 37379 NRC Resident Inspector U. S. Nuclear Regulatory Commission 1260 Nuclear Plant Road Spring City, TN 37381 I sm w unc nnnum mv , vrs 1 0FFICE Ril:0RS RII:0RP . a RII:RC Rll Ett RI:0RA INITIALS -

mE JJAUNN J CEVMS ByJ _ Batn Om e7 /10 / 97 azt to /97 07/10 297 02sN / 97 07/M/97

/Q - GJ e vee (W Grd - 4 ) ..,

OFFICIAL RECORM0PY i DOCUMENT M E: H\1970 PEN.ENT972325 MM[\ FINAL. U

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