IR 05000327/1998014
| ML20206N423 | |
| Person / Time | |
|---|---|
| Site: | Sequoyah  |
| Issue date: | 12/04/1998 |
| From: | NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II) |
| To: | |
| Shared Package | |
| ML20206N420 | List: |
| References | |
| 50-327-98-14, 50-328-98-14, NUDOCS 9812180048 | |
| Download: ML20206N423 (16) | |
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l- U. S. NUCLEAR REGULATORY COMMISSION REGION ll
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Docket Nos: 50-327, 50-328 i License Nos: DPR-77, DPR-79 Report Nos: 50-327/98-14,50-?,28/98-14 Licensee: Tennessee Valley Authority .
Facility: Sequoyah Nuclear Plant s
Location: 2600 Igou Ferry Soddy-Daisy TN 37379
Dates: November 2-6,1998 Inspectcrs: W. Sartor, Senior Radiation Specialist (Team Leader)
D. Jones, Senior Radiation Specialist J. Kreh, Radiation Specialist
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l G. Salyers, Emergency Preparedness Specialist Approved by: K. Barr, Chief Plant Support Branch Division of Reactor Safety
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Enclosure
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9812180048 981204 PDR
0 ADOCK 05000327 PM
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EXECUTIVE SUMMARY SEQUOYAH NUCLEAR PLANT NRC Inspection Report Nos. 50-327/98-14,50-328/98-14 This routine, announced inspection involved the observation and evaluation of the biennial emergency preparedness exercise for the Sequoyah Nuclear Plant. This NRC/ FEMA-evaluated exercise was a plume exposure and post-plume exposure exercise with offsite participation by the State of Tennessee and local governments. Participation also included the NRC Chairman, NRC Headquarters, and Region 11 with a Base Team and a Site Team. The plume exposure exercise was conducted on November 4,1998 from 8:00 a.m. to 3:15 p.m. This report summarizes the observations of the four-person NRC team that assessed the adequacy of the
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licensee's emergency preparedness program as it implemented its emergency plan and procedures in response to the simulated accident. A separate FEMA report will be issued that evaluates the performance of the States and counties. The FEMA report will also address the post-plume exposure exercise conducted on November 5,199 The NRC team observed the licensee's response in the Control Room Simulator (CRS), the
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Technical Support Center (TSC), the Operational Support Center (OSC), and the Central Emergency Control Center (CECC). Based on the performance observed, the team concluded that the licensee successfully demonstrated its ability to implement the Emergency Plan and implementing Procedure Proaram Areas Evaluated and Results Scenario - The scenario developed for this exercise was effective for testing the integrated emergency response capability of the onsite and offsite emergency organization Control Room Simulator - The Shift Manager promptly recognized the emergency action level and declared the Alert. Good command and control was observed as the interim Site Emergency Director (SED) implemented emergency procedure Technical Support Center - TSC personnel were focused, professional and generally effective in carrying out their assigned functions and responsibilities. Command and control of TSC operations by the SED was excellent, with the significant exception of failure to notify the State within 15 minutt.s of declaring the Site Area Emergency (Exercise Weakness).
Operational Support Center - The OSC's performance was satisfactory. The updated facilities and electronic equipment greatly improved the OSC's capabilities. Command and controlin the OSC was good. Good communication was observed between the TSC and OSC. Emergency repair teams were effectively formed and tracked; however, long and sometimes repetitive briefings delayed the dispatch of the team Central Emeraency Control Center (CECC) - The CECC functioned efficiently and effectively in meeting the exercise goals and objectives. Command and control of facility operations by the CECC Director was goo Licensee Critiaue - The licensee's controller / evaluator organization was effective in identifying performance issues. The licensee was timely in addressing corrective actions for the delayed notification of the site area emergenc ;
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l Report Details IV. Plant Support P4 Staff Knowledge and Performance in Emergency Preparedness (EP)
P Exercise Scenario l Inspection Scope (82302)
The inspectors reviewed the exercise scenario to determine whether provisions had been made to test the integrated capability and a major portion of the basic elements of the licensee's plan.
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! Observations and Findinas The licensee submitted the scope and objectives for the biennial emergency exercise to the NRC with a letter dated August 18,1998. The exercise scenario package was ,
l submitted with a letter dated September 18,1998. A review of the package indicated l that the scenario was adequate to exercise the onsite and offsite emergency ,
i organizations of the licensee and provided sufficient information to the offsite agencies '
l for their participation in the exercis l l Conclusion
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The scenario developed for this exercise was effective for testing the integrated emergency capability of the onsite and offsite emergency organization P Emeraency Response Facility (ERF) Observations and Critiaue l Exercise Evaluation Scope During this inspection, the inspectors observed and evaluated the licensee's biennial full-participation, emergency preparedness exercise in the Control Room Simulator I (CRS), Technical Support Center (TSC), Operational Support Center (OSC), and the I Central Emergency Control Center (CECC). The inspectors assessed licensee recognition of abnormal plant conditions, classification of emergency conditions, notification of offsite agencies, development of protective action recommendations (PARS), command and control, communications, and the overall implementation of the Emergency Plan. Observations in the CRS were made during the early phases of the emergency to include the turnover of Site Emergency Director responsibilities to the ;
I TSC. In addition, the inspectors attended the post-exercise critique to evaluate the
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licensee's self-assessment of the exercise. Acceptance criteria are contained in Appendix E to 10 CFR Part 50, site Emergency Plan, Emergency Plan implementing j l procedures, and industry guidance in NUREG-0654/ FEMA-REP-1, Revision 1, " Criteria '
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Preparedness in Support of Nuclear Power Plants." ;
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l ERF Observations. Findinas. and Facility Critiaues j 1 Control Room Simulator (CRS) l l
Observations and Findinas The initial emergency response was observed by the inspector in the CRS. Following the briefing of the simulator crew, the simulator was started at 8:00 a.m. Annunciators i
alarmed at 8:10 a.m. as the off-normal conditions began. The Shift Manager promptly l recognized the emergency action level for an Alert and made the declaration at )
8:23 a.m. The Shift Manager cssumed Site Emergency Director (SED) responsibilities 1 and initiated the paging system for the emergency response organization call-out, and i then telephonically notified the Operations Duty Specialist for the State of Tennessee
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l notification. The SED demonstrated go.od command and control as he implemented l
the Emergency Plan and procedures, and directed frequent status briefings to keep the l CRS shift apprised of the situation. At 8:55 a.m., the responsibilities for the SED were
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I Conclusion The Shift Manager promptly recognized the emergency action level and declared the Alert. Good command and control was observed as the interim Site Emergency Director implemented emergency procedure Technical Support Center (TSC) .
I Observations and Findinas ;
i Following the Alert declaration at 8:23 a.m. and the sounding of the accountability alarm six minutes later, designated personnel began to arrive at TSC. All facility personnel were in place by 8:39 a.m., at which time a preliminary staff briefing was l conducted. After a telephonic tumover from the Shift Manager, who was the interim l SED in the CRS, the designated SED assumed the responsibilities of his position and j declared the TSC activated at 8:55 a.m.
l l TSC personnel were focused, professional and generally effective in carrying out their l assigned functions and responsibilities. The TSC staff demonstrated clear communications and strong teamwork. Personnel continuously reviewed and assessed plant conditions using plant data (simulator-driven) displayed in real time on several computer terminals. Tasks and priorities for OSC response teams were formulated by the Technical Assessment Team and promptly communicated to the OSC. Command and control of TSC operations by the SED was excellent (with the exception of one crucialissue, discussed below). The SED provided timely and informative briefings to the TSC staff, and periodically huddled with his principal staff members to receive status summaries and discuss mitigation strategie l Declarations by the SED of a Site Area Emergency (SAE) at 9:30 a.m. and a General
, Emergency (GE) at 11:42 a.m. were timely and correct based on simulated plant ;
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conditions. However, the SED failed to expeditiously notify the CECC Director of the SAE declaration as required by procedure. Emergency Plan Implementing Procedure (EPIP)-6, " Activation and Operation of the Technical Support Center", Revision 24, stated in Appendix B that the SED was responsible for determining the emergency classification and for reporting classification changes to the CECC Director "within about five minutes". The report of the SAE declaration was made to the CECC Director at about 10:05 a.m., and the notification to State authorities of the upgrade in emergency classification was made at about 10:10 a.m. This internal reporting delay resulted in a time interval of nL out 40 minutes between the SAE declaration and the State notification. This was not in accordance with NRC and licensee requirement Section 3.4.6 of EPIP-1, " Emergency Plan Classification Matrix", Revision 23, specified that "The State shall be notified within 15 minutes of the classification." Failure to notify the State within 15 minutes of declaring the SAE was identified as an Exercise
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Weakness, a finding which will be tracked as inspector Follow-up Item (IFI) 50-327, 50-328/98-14-01. The licensee initiated Problem Evaluation Report No. SO981570 to track the formulation and completion of corrective actions for this matte Although most of the TSC status boards were accurate and frequently updated, the board showing radiological conditions and dose projections was not well maintained, with information usually 30 to 60 minutes old by the time it was update Conclusions TSC personnel were focused, professional and generally effective in carrying out their assigned functions and responsibilities. Command and control of TSC operations by the SED was excellent, with the significant exception of failure to notify the State within l
15 minutes of declaring the SA b.3 Operational Sucoort Center Observations and Findinos The Operational Support Center (OSC) was operational 17 minutes after the Alert declaration. Each staff member effectively implemented his/her specific portion of the applicable OSC procedures. The OSC was organized and the staff worked well together. The OSC Manager communicated effectively with the TSC and displayed good command and control when delegating tasks to his staff. Ccmmunications among the staff in keeping appropriate personnel informed and initiating repair teams was both effective and professiona l The OSC was kept informed of changing plant conditions by the OSC Manager as well as by monitoring TSC briefs in the OSC. The OSC was well equipped to support all of !
the demands placed upon the facility. Ample supplies were available for the repair teams. Communication capabilities were good. Personnel dose records and respirator qualifications were computerized, and hard copies of procedures and drawings were readily available as well as having the ability to print them from a local computer. Good radiological controls and monitoring were established in the OS l I
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Emergency Response Teams (ERTs) were pre-formed and dressed in anti-contamination clothing in preparation for task assignments. ERT authorization forms used for each team contained essentialinformation, and ensured consistency during team briefings and preparatio ERTs dispatched from the OSC were effectively tracked as well as Operational Teams dispatched from the control room and Radiological and Chemistry Teams dispatched from the Health Physics area. ERTs were briefed, provided health physics coverage, and radios for maintaining communication with the OSC. The OSC maintained good communication with the teams in the field. Upon returning to the OSC, the teams were debriefed as required by procedur Ten ERTs were dispatched from the OSC. The inspector observed the briefing of three of those teams. The inspector noted that the briefs were excessively long and detailed for the tasks to be accomplished. Some examples of long and detailed briefings were: Team number one was requested to visually inspect common station service transformer (CSST) "B to determine if it was available for service. During the brief, the team prepared for potential equipment and relay repairs. Team number three reviewed in detail the procedure for reassembly of 1 A-S Auxiliary Feedwater Pump. Even though teams were preassembled, excessively detailed briefs resulted in taking, on average, approximately one hour to dispatch each repair team once it was assigned a tas Conclusion The OSC's performance was satisfactory. The updated facilities and electronic equipment greatly improved the OSC's capabilities. Comraand and control in the OSC was good. Communication between the TSC and OSC was good. Emergency repair teams were effectively formed, briefed, dispatched and tracked. Repair team briefs were excessively long and detailed for the tasks and resulted in delaying the dispatch of the teams.
b.4 Central Emeraency Control Center (CECC)
Observations and Findinas The CECC was promptly staffed and activated iollowing the declaration of an Aler The CECC Director announced that the facility was operational within 38 minutes of being notified of the emergency by the Operations Duty Specialist. The inspectors verified that the minimum staffing required by the Radiological Emergency Plan was in place and further noted that the CECC was fully staffed and functional. Emergency response procedures were available and in use by the CECC staff. The facility was properly equipped and the equipment was functioning effectively. Efficient operation of the CECC was maintained by effective management and control. The CECC Director provided frequent updates to his staff to keep them fully informed. Logs and status boards displaying pertinent information were kept current. Good communications within the CECC and with other emergency response facilities were maintaine Offsite dose assessments were frequently calculated based on field monitoring reports
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conditions. With the exception of the SAE notification discussed above, the Federal, State, and local agencies were promptly notified of plant status, radiological impacts, and recommended protective measure Conclusion The Central Emergency Control Center functioned efficiently and effectively in meeting the exercise goals and objectives. Command and control of facility operations by the CECC Director was goo b.5 Licensee Facility Critiaues and Presentation to Manaoement Following the exercise, the licensee conducted facility critiques in which the players provided their own assessment of their performance and identified areas that needed improvement. The post-exercise critiques in the TSC, OSC, and CECC were observed to be thorough, open, and self-critical. The licensee controller / evaluator organization then conducted detailed discussions, reviewed documentation, and conducted interviews as required to develop their critique results. On November 6,1998, a presentation to licensee management was made that properly summarized the exercise as successful, with a deficiency identified for the failure to properly notify the state of the escalation to a Site Area Emergency within 15 miautes. Corrective action had been initiated with a Problem Evaluation Report, and a Revision 24 of CECC EPIP-1 was provided to Region ll on December 2,1998, with changes made to ensure more timely feedback of the notification proces Conclusion The licensee's controller / evaluator organization was effective in identifying performance issues. The licensee was timely in addressing corrective actions for the delayed notification of the site area emergenc V. Manaaement Meetinos X1 Exit Meeting The Team Leader presented the inspection summary to licensee management on November 6,1998. The summary indicated the exercise was fully satisfactory, with the exception of the exercise weakness identified for the delayed notification to the State of Tennessee for the Site Area Emergenc . _ - - . . - - . . - - -. . - . .. -
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PARTIAL LIST OF PERSONS CONTACTED !
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Licensee I M. Bajestani, Site Vice President C. Burton, Engineering and Support Services Manager H. Butterworth, Operations Manager N. Catron, Emergency Preparedness Manager l R. Driscoll, Training Manager R. Kitts, Corporate Emergency Preparedness Manager l D. Koehl, Assistant Plant Manager M. Munroe, Emergency Preparedness Manager ;
R. Proffitt, Licensing Compliance Engineer j INSPECTION PROCEDURES USED IP 82301: Evaluation of Exercises for Power Reactors IP 82302: Revie a of Exercise Objectives and Scenarios for Power Reactors ITEMS OPENED 50-327, 328/98-014-01 IFl Exercise Weakness-Failure to notify the State within 15 minutes of declaring the SA Attachment (8 pages):
Exercise Goals, Objectives, Narrative Summary, Time Line, and Significance of Key Events
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ATTACMENT L ,
' SQN 1998 Graded Exercise
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The Radiological Emergency Plan Ingestion Pathway Exercise will consist of the participation by TVA, State, and Federal emergency organizations:
. Central Emergency Control Center will fully participate and be evaluate . Technical Support Center will fully participate and be evaluate . Operations Support Center will fully participate and be evaluate . Joint Information Center will fully participate and be evaluate . State Emergency Operations Center will fully participate and be evaluate . Risk Counties Emergency Operations Centers will fully participate and be evaluate . State Field Coordination Center will fully participate and be evaluate . State Radio;ogical Monitoring Control Center will fully participate and be evaluated. . State Field Teams will fully participate and be evaluate GOALS TVA's goals for the drill are as follows:
1. Allow plant and offsite personnel to demonstrate and test the capabilities of the emergency response organization to protect the health and safety of plant personnel and the general public in accordance with the Nuclear Power- Radiological Emergency Plan (NP-REP), site Emergency Plan implementing Procedures (EPIPs), and the Central Emergency Control Center (CECC) EPlP .' Allow personnel to demonstrate and test the capabilities of the emergency response organization to sample the environs for necessary ingestion pathway data and support secovery and reentry activitie . Provide an interactive drill to ensure proficiency of onsite emergency response capabilitie Provide training for emergency response personne . Identify emergency respinse capabilities that are in need of improvement or revisio OBJECTIV5S A. Control Room / Simulator Demonstrate the ability of the Shift Manager to recognize conditions, classify emergencies, make required notifications in a timely manner, and assume the initial responsibilities of the Site Emergency Director (SED). Demonstrate the ability of the Shift Manager to maintain effective command and control of control room activitiesand perform classification analysis Demonstrate the ability of the control room staff to make timely analysis of the incident Demonstrate the ability of the control room staff to use appropriate radiological emergency procedures Demonstrate the ability of the control room staff to continuously evaluate information, redefine / confirm
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conditions and event classifications B. Technical Support Center (TSC) Demonstrate the SED's ability to provide effective direction, command and control, to manage activities in a f manner that promotes event classification, analysis, or mitigation of an event and to perform periodic briefings for TSC/OSC staff and personne TVA Emergency Preparedness Page 7 . Revised: 9/16/98 4 25 PM
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SQN 1998 Graded Exercise I l
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) Demonstrate the ability of the TSC staff to use appropriate procedures, solve problems related to incident identification l i
I Demonstrate the TSC's ability to determine the appropriate sampling and monitoring required to support l l
- accident mitigation, perform timely assessrrents of onsite radiological conditions, and formulate, coordinate, implement, and track on site protective actions.
! Demonstrate the TSC's ability to maintain effective communication between the OSC, control room, CECC, j and various groups within the TS . Demonstrate ability of the TSC to continuously evaluate available information, redefine / confirm plant
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conditions and event classifications, and if required assemble onsite personnel within the protected are . Demonstrate the ability of the TSC to effectively assume communication with environmental monitoring vans from the Radeon La C. Operations Support Center (OSC) Demonstrate the ability of the OSC Manager, through effective command and control, to coordinate and initiate activities in a timely manner and use appropnate procedure . Demonstrate ability of the Radcon personnel to use appropriate procedures and follow Radcon and ALARA practices to enst ce adequate worker protection and perform effective inplant survey . Demonstrate ability of the OSC to track changing radiological conditions through survey results and/or inplant monitors, controlintemal and extemal exposures and personnel contamination of onsite emergency workers,
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and incorporate the information into personnel protective actions and exposure trackin D. Central Emergency Control Center (CECC)
~ Demonstrate the ability of the Operations Duty Specialist to make initial notifications to State agencies in a timely manne . Demonstrate the ability to transfer offsite responsibilities from the TSC to the CEC . Demonstrate the ability of the CECC Director to maintain effective command and control and promote internal comrqunication . Demonstrate the ability of the CECC to provide emergency classifications, protective action recommendations, plant conditions, and dose assessment information to the State in a timely manne . Demonstrate the ability to effectively obtain radiological survey information from the field, keep the field teams informed of emergency conditions, and provide them with exposure contro . Demonstrate the ability of the CECC staff to use appropriate procedures and equipment, and to periodically evaluate available information and redefine / confirm plant conditions and event classification . Demonstrate the ability of the CECC staff to obtain field data needed to develop dose assessments in a timely manne . Demonstrate the ability of the CECC staff to analyze current plant conclitions, identify projected trends, and I determine the potential consequences TVA Emergency Preparedness Page8 Revised: 9/16/98 4.25 PM
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E. Drill" Specific . Demonstrate the ability to conduct post drill critiques.
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' Demonstrate the adequacy of control room and emergency centers facilities, resources, equipment, and communication systems to support emergency operation l
, Demonstrate the ability to alert and mobilize emergency response center personnel and activation of the emergency centers within approximately one hour.
l Demonstrate the ability to conduct habitability surveys for the TSC, OSC, Control Room, and all assembly area l
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Demonstrate the ability to maintain effect ve communicatior between the Technical Support Center,
. j Operations Support Center, Central Emergency Control Center, Control Room / Simulator, and NR F. Environmental Monitoring (Primary Focus) Demonstrate the ability of the environmental monitoring teams to effectively utilize procedures to perform l dose rate surveys and t5 collect and analyze radiological sample I Demonstrate the environmental monitoring team's abilities to follow cnntamination control procedures !n field condition ~'~
- Demonstrate the adequacy of the environmental monitoring vans to support emergency operation l (monitoring equipment, supplies, communication equipment, etc.) Demonstrate the ability of the site to timely and effectively activate and establish communication with environmental monitoring vans.
l Demonstrate ability of the site to timely and effectively transfer control of the environmental monitoring ' vans
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to an offsite cente . Demonstrate ability to effectively dispatch and control radioiogical/ environmental monitoring teams, i coordinate with the State when applicable, and obtain, analyze, and utilize meteorological, onsite and offsite radiological conditions, and source term information to develop dose assessments in a timely manner, 7.- Demonstrate ability of the environmental monitoring team personnel to monitor their accumulated dose, report their accumulated doses to the Environs Assessor / Field Coordinator, and receive proper authorization
for emergency exposures if require G. Ingestion Pathway Sampling (Primary Focus) - Demonstrate the ability of the environmental monitoring teams to effectively utilize procedures collect and analyze soil samples for radioactivit ' Demonstrate the ability of the environmental monitoring teams to effectively utilize procedures to collect and analyze vegetation samples or one other dry terrestrial sample for radioactivity. (food crop or fodder / feed) Demonstrate the ability of the environmental monitoring teams to effectively utilize procedures to collect and analyze at least one other wet terrestrial sample for radioactivity. (rain water or well water)
TVA Emergency Preparedness Page 9 Revised: 9/16/98 4 26 PM
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SQN 1998 Graded Exercise Demonstrate the ability of the environmental monitoring teams to effectively utilize procedures to collect and analyze at least one milk sample for radioactivi . Demonstrate the adequacy of the environmental monitoring vans to support ingestion pathway emergency operations. (monitoring equipment, supplies, communication equipment, etc.)
H. Public Information / Joint Information Center l Demonstrate the ability of the CECC Information Manager to display effective command and control of the overall communications respons ; Demonstrate the adequacy of the CECC communication staff facilities, resources, equipment, and communications system to support emergency operation J l
1. NRC Follow UP ltems 1 NONE J. Drill Credit
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The following drills will be credited as part of the exercise: CECC/ State Communication Drill 2. TSC/CECC Communication Drill l Plant Radeon Drill (In-Plant Radiation Monitoring) Plant Radiological Monitoring Drill ( Environs Monitoring ) Radiological Dose Assessment Drill (CECC) Fire Drill Ingestion Pathway Exercise
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TVA Ernergency Preparedness Page 10 Revised: 9d6/98 4 26 PM
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SQN 1998 Graded Exercise
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Narrative Summary Sequoyah Nuclear Plant Annual Exercise November 4-5,1998 Unit 1 Initial Conditions:
. The exercise begins with Unit 1 at full power for the past 202 days
. The Unit 1 core is near the end of life. A refueling outage is scheduled to begin in 90 day . . Radiation levels in the plant are normal
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. Reactor Coolant Chemistry results indicate no leaking fuel bundles on Unit 1
. SSPS Train A is in Test undergoing monthly testing l . TDAFW pump is undergoing disassembly and inspection of inboard bearings. Estimated completion in 6
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. RHR 1 AA is undergoing bi-monthly inspection of the impeller, casing, and wear rings for wear, pitting, or erosion in preparation for the upcoming outage. Estimated Completion in 48 hour5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br /> ;
Unit 2 Initial Conditions:
. The exercise beginswith Unit 2 at full power for the past 8 days after a 29 day refueling outage
. Radiation levels in the plant are norma!
. Reactor Coolant Chemistry results indicate no leaking fuel bundles on Unit 2
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Weather:
. High pressure is located over North Carolina and low pressure over Oklahoma this moming. Clear skies with temperatures in the low 30s this morning will give way to increasing clouds this aftemoon with temperatures rising to near 60. The low pressure area and associated cold front will move into westem Tennessee by this evening. Southerly winds will be inct, easing from light to moderate levels during'the
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i At the start of the exercise, unknown to the operators, the discharge check valve of SI pump 1 AA has been blocked by debris and the pipe is 97% blocked. At 10 minutes into the scenario, Common Station Service Transformer C !
shorts intemally and explodes. Substantial damage was done to Start Bus 1B during the explosion and it has a )
fault to ground. The loss of Start bus 1B causes Unit Board 18 and 1D to lose power. Due to the current surge, minor damage was done to a bus in the Unit Board 1D between Compartments 7 and 8. Debris and smoke will be visible coming from the Switchyar l Unit 1 RCPs #2 and #4 willlose power due to the loss of Unit Boards 1B and 1D. The rea,ctor, however, does not I trip as designed. Operators manually trip the reactor and declare an ALERT based on EAL 2.3 (ReactorPower ;
>5% andnot decreasing aMera validauto tnp signalbut a manualinp from the ControlRoom is successfu Around T=0:30, a tube in Unit 1 Steam Generator #1 begins leaking due to high thermal stresses caused by the l ATWS and loss of RCPs 2 and 4. By T=0:45 minutes in the scenario, the leak has increased to around 45 gallons per minute (gpm). Shortly after this, the operators must start a second charging pump to maintain pressurizer level.
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SQN 1998 Graded Exercise Around T=1:10, several more tubes suddenly failin Steam Generator #1 due to high fluid velocities around the previously leaking tube. Water level begins increasing in Steam Generator #1 as the primary to secondary leak rate exceeds the steaming rate from that Steam Generator. At this point, the 1 AA Safety injection Pump (SIP)
generates high pressure but, due to the high RCS pressure, the low flow indicating a clogged discharge line cannot be determined until RCS pressure is reduced. When discovered, the operators may chose to isolate the 1 AA Safety injection Pump. By T=1:30, the water level in Steam Generator #1 has reached the steam lines. Shortly thereafter, the water in the steam line causes a water hammer with the Steam Generator Safety Valve snapping the spring that normally holds the valve closed. With the spring broken, the valve will not close. Operators identify l
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the situation and declare a S/TEAREA EMERGENCV around T=1:30 based on EAL 1.2.3 (Steam Generator Tube Rupture that results in a Safety injection actuation) and EAL 1.3.4 (Secondary side release outside containment from a ruptured Steam Generator that cannot be terminated in less than 15 minutes).
, At around T=1:40, a loose connection in Unit Board 1C arcs and damages Compartment 10 (Normal feeder l breaker to Shutdown Board 1BB) such that the breaker cannet be removed. When Diesel Generator 1BB attempts l to start, the fault on the Unit Board is sti!! holding the Shutdown Board 1BB to ground. The Diesel Generator
! experiences high current and trips when the cable is damaged by the high current. This leaves the 1BB Centrifugal Charging Pump (CCP),188 Safety injection Pump,188 Residual Heat Removal Pump (RHR),1BB l Containment Spray Pump (CS), and the 1BB Motor Driven Auxiliary Feed water Pump (MDAFW) out of service due to a loss of electricity. A few minutes later, the 1 AA Centrifugal Charging Pump motor shorts and trips with a phase to ground short. This leaves only the 1 AA SI pump a potential source of injectior, unless the operators chose to isolate it earlier. Neither the Utility Bus breaker nor the Diesel Generator C-S crosstie breaker is functional for Shutdown Board 1BB. ---
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Reactor Coolant System levels continue to drop as the liquid leaks into the Steam Generator and to the environs
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via the broken safety valve. The Operations Support Center will try to gag the safety valve but the heat, two phase flow, and Steam Generator pressures will prevent them from being successful at this tim At approximately 3:45 into the scenario, the Reactor Vessel Level Indication System (RVLIS) reaches 40%. This is point where steam cooling will no longer protect the fuel from overheating. Based on the inability to properly cool the core, the site will declare a GENERAL EMERGENCY based on EAL 1.1.4 (va//dRVL/S/ eve / <40% on L/-68-368 or371 with no RCPrunning), EAL 1.2.3 (Steam Generator Tube Rupture thatresults in a Safetyinjection actuation), EAL 1.2.4 (validRVLISlevel<40% on LI-68-368 or371 with no RCPrunning), and EAL 1. (Secondary side release outside containment from a ruptured Steam Generator that cannot be terminatedin less than (Sminutes). Without adequate steam cooling, the fuel begins to heat up. After about 15 minutes of heating, the cladding begins to perforate and increased noble gas and iodine releases begi After about 45 minutes of heating (T=4:30), the cladding reaches temperatures 1300 F high enough to cause extremely Sgh fuel pellet temperatures resulting in greatly increased noble gas and iodine releases. Core Exit Thermocouples indicate peak temperatures around 1700*F above the core by T=5:00. By T=5:30, equipment has been repaired that allows Emergency Core Cooling System (ECCS) equipment to be put back in service. These l pumps allows water to be injected to the Reactor Vessel to cool the core. By T=6:30, the reactor pressure has
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dropped. This results in reduced steam flow through the damaged safety which allows OSC teams to gag the safety valve With the major release pathway isolated, the plant enters termination and recovery procedure Offsite field teams continue to sample to verify the lack of a release as well as to track the plume that has been j released to this poin The exercise is terminated at approximately T=7:0 TVA Emergency Preparedness Page 14 Revised. 9/16/98 4.26 PM
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y 199 Anm> I Execse 04evised. July to,1998 Sequovah J Nuclear Plant "0~**"*'**' 0'
Start Time:0800EST-f 1.00 2:00 3 00 i 4.00 5.00 8:00
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} 0: E0 CSST C emplodes und damages Start Bus 88 S 7:00 Esercise Torneke e'd
- 0:10 A TWS . ntenual Trk' Sur:esslut D
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'SQN 1998 Graded Exercise l
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l Signi"icance o" (ey Events l CCP 1AA Combined with the loss of Shutdown Board 1BB causes loss of all CCP capability to Unit Redt.ction of ECCS capacity is necessary to allow core overheating and damage.
i RHR 1AA L Combined with the loss of Shutdown Board 188 causes loss of all RHR capability to Unit Reduction of ECCS capacity is necessary to allow core overheating and damag St 1AA Check Valve Combined with the loss of Shutdown Board 188 causes loss of all Si capability to Unit Reduction of ECCS capacity is necessary to allow core overheating and damag TDAFW Pump Reduces ability to cool down the reactor due to damage to #1 Steam Generator ,and when l . combined with loss of Shutdown Board 1BB, leads to inability to feed #3 and #4 Steam Generato CSST'C' explosion _
Key event in loss of Start Bus 18 and inability to provide normal power to Unit Start Bus 18 damage Eliminates power feeds to Units-Board 18 and 1D, thereby eliminating power to Reactor Coolant Pumps for loops 2 and 4 (initiating a trip signal). Also eliminates power Unit Board 1D which is the l backup power source for Shutdown Board 188, l
ATWS, Manual Trip Basis of ALERT declaration l SG Tube Rupture (SG Ruptured)
i Source of offsite release (with Steam Generator Safety Valve failure)
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SG Safety Failure (SG Faulted)
Source of offsite ielease (with Steam Generator tube rupture)
Unit Board 1C Fault Eliminates primary poiver supply to half of ECCS equipment (B Train equipment)
Unit Board 1D Fault Eliminates alternate power supply to half of ECCS equipment (B Train equipment)
DG 188 fail to Start Eliminates emergency power supply to half of ECCS equipment (B Train equipment)
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Utility Bus / DG Bus Crosstie unavailable Eliminates rapid return of power supply to B Train equipment TVA Emergency Preparedness Page 16 Revsed: 9/16/98 4 25 PM