ML20210R882

Forwards Informal Guidance for Observation of Shutdown Operation.Document Consists of Existing Insp Guidance for Four Regions Suppl by Risk Insights Gained from Work on Shutdown Rulemaking.With 990709 Release Ltr

ML20210R882
Person / Time
Issue date:	04/07/1999
From:	Holahan G NRC (Affiliation Not Assigned)
To:	Caldwell J, Jerrica Johnson, Wiggins J NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I), NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II), NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
References
NUDOCS 9908170245
Download: ML20210R882 (25)

Text

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.f . . April 7, 1999 MEMORANDUM TO: James T. Wiggins, Deputy Regional Administrator, RI Jon R. Johnson, Deputy Regional Administrator, Rll James L. Caldwell, Deputy Regional Administrator, Rlli  !

Thomas P. Gwynn, Deputy Regional Administrator, RIV

/ original signed by Carl Berlinger for/

FROM: Gary M. Holahan, Director Division of Systems Safety and Analysis Office of Nuclear Reactor Regulation

SUBJECT:

INFORMAL GUIDANCE FOR OBSERVATION OF SHUTDOWN ,

I OPERATION (TAC NO. MA0808)

IUBUC COCUMENT ROOM Regional and headquarters steff have , pent cons!derable effort developing the attached informal guidance for monitonng shutdown operations; ine attwi,td .iocunMht isjKeegecg77 of existing inspection guidance from the four regions supplemented by risk insights' gained from'-

the work on shutdown rulemaking. The intent of the attached document is to ensure that the level of safety provided by current and mostly voluntarv industry practices is maintained. This is consistent with the Commission's direction in the staff requirements memorandum (SRM) dated December 11,1997," Staff Requirements-SECY-97-168-Issuance for Public Comment of Proposed Rulemaking Package for Shutdown and Fuel Storage Pool Operation," in which the ,

Commission stated, "The Commission expects the staff to continue to monitor licensee performance, through inspeecns and other means, in the area of shutdown operations to ensure that the current level of safety is maintained.* The attached document was originally intended to be included as an inspection procedure in the core inspection program. However, as you are aware, the staff is currently reviewing the inspection program and is expected to develop a new, more risk informed and efficient program (Baseline Inspection Program), by January 2000; Accordingly, it was determined to be inappropriate to incorporate a new shutdown inspection procedure into the existing inspection program which may only be in effect for a few months. Shutdown operations will be included in the new baseline inspection program. Therefore, the attached document is being provided to you for your consideration, in the interim, for use in shutdown operation inspections for the upcoming spring and fall outages.

l Attachments: As stated CONTACT: Mohammed Shuaibi, SRXB/DSSA i 415-2859 )

DISTRIBUTION: .

I File Center- GHolahan . TCollins JWermiel EWeiss WLyon MShuaibi WDean- CHolden JKlingler Mbanerjee Rbarrett AEl-Bassioni MPohida DChawage DLew JLinville WRogers RBemhard RLanksbury PPelke SDuPont JTapia TGody Jr.

TFoley .SRXB R/F BSheron DOCUMENT NAME: G:\ GARY.MEM *See previous concurrence  ;

OFFICE: SRXB:DSSA SRXB:DSSA SRXB:DSSA DSSA -

T NAME: MSHUAIBl* EWEISS* JWERMIEL* GHOLAH N DATE: 4/2/99 4/2/99 4/2/99 4/f/99 \

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OFFICIAL RECORD COPY 9908170245 990407 PDR ORG NRRA i

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l ATTACHMENT 1 INFORMAL GUIDANCE FOR OBSERVATION OF SHUTDOWN OPERATION 4

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s s OPERATING PLANT SHUTDOWN BACKGROUND The regulatory basis for this document can be found in Staff Requirements Memorandum (SRM) dated December 11,1997, The Maintenance Rule, Generic Letter (GL) 8817 and related correspondence (pressurized water reactors (PWRs) only), and Plant Technical Specifications (TS). The Commission in the SRM dated December 11,1997, in response to

' SECY-97-168, directed the staff to " continue to monitor licensee performance, through inspections and other means, in the area of shutdown operations to ensure that the current level of safety is maintained." Additionally, in order to meet the Maintenance Rule, licensees must perform safety assessments, qualitative or quantitative, prior to taking equipment out of service for maintenance. These assessments, for shutdown conditions, are performed to assist the licensee in reducing the potential for core damage and fission product release. An understanding of the key parameters presentedin this document is important to performing an adequate assessment during shutdown conditions. GL 88-17 provided recommendations to address concerns related to loss of decay heat removal (DHR)in PWRs. In response to this GL, licensees submitted responses in which they committed to certain recommendations.

Risk informed outage planning for PWRs should recognize the step increase in risk that occurs

- when the reactor coolant system (RCS) boundary is breached and steam generators cannot be used for DHR and the step increase in risk that occurs when mid-loop operation conditions are reached. Risk informed outage planning for boiling water reactors (BWRs) should recognize the risk significance of maintaining safety relief valve (SRV) operability until the vessel head is removed, the risk significance of establishing an attemate DHR path via the suppression pool, and the risk significance of maintaining DHR isolation on Level 3 to control potential reactor coolant drainage. In addition, a licensee for a PWR or BWR should have an outage plan that ensures that barriers required for flood and/or fire control are intact or ensure that compensatory measures are taken to protect operable structures, systems, and components (SSCs) and SSCs which provide a key safety function.

OBJECTIE ,

To monitor plant operations while shut down to ensure that the licensee implements:

1. Controls for the operatibn of SSCs which suppori or perform key safety functions' in accordance with Technical Specifications (TS), license conditions, commitments and approved procedures.

'2. An effective configuration management program.

2. An outage plan that uses effective risk management.

I Five key safety functions are decay heat removal, inventory control, reactivity control, electrical power, and containment. Licensees may specify additional key safety functions.

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DOCUMENTATION OF OBSERVATIONb Items included in this document are derivM from regulatory requirements as well as voluntary licensee practices that have represented an adequate defense-in-depth practice in industry.

Sources for voluntary practices include the guidance in NUMARC 91-06, NRC generic

. _ communications and information reports (e.g., information Notices (ins), GLs, NUREGS, etc.).

and other insights gained from years of evaluating shutdown risk. Therefore, because of the inclusion of voluntary actions, some observations will not be enforceable even though the expectations stated in this document are not met. In such cases, the inspector should document his/her observations as evaluative. This documentation of observations will allow for a later assessment of industry performance against the current level of safety as stated in the Commission's SRM. Enforceable findings should be addressed in accordance with the normal enforcement process.

GENERAL GUIDANCE

1. Prior to the outaae and in consultation with a Senior Reactor Analyst. review the i licensee's outaae otan and:  !

1. Identify risk-significant activities or combinations of activities that could potentially j affect any key safety function.

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2. Verify that the licenst s has considered the risk associated with performing the activities identified in item 02.01.a.1.

3. Verify that the licensee has considered industry experience and previous site specific outage implementation problems as identified in corrective action reports and quality assurance audits.

4. Verify that the licensee's outage plan has been independently reviewed. j

2. Licensee Control of Outaae Activities.

a. Procedures. Prior to the outage, verify that the licensee has normal and off-normal procedures covering key safety functions and. key plant parameters,

b. TS and Other Reauirements.

1. On a sampling basis and in c'onjunction with performing inspection Procedure 71707, verify that operators are aware of applicable TS, license conditions, and licensee commitments associated with the key safety functions and that these requirements are met.

2. In conjunction with performing Inspection Procedure 71707, verify that licensee use of overtime for licensed reactor operators and others who are engaged in risk-important activities are consistent with regulatory requirements and licensee administrative procedures.

c. Defense-in Deoth.. Verify that the licensee maintains defense-in-depth commensurate with the outage plan for key safety functions and applicable TS when taking equipment out of service.

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d. Oversiaht of Work.

1. Verify that the licensee provides workers, including contractors, sufficient training to ensure that the activities are completed satisfactorily.

2. Verify that contract workers received a level of supervision and quality assurance monitoring equivalent to that afforded facility workers for the tasks to be accomplished.

e. Emeroent Work or Unexoected Conditions. Verify that emergent work and unexpected conditions are controlled in accordance with outage control procedures.

f. Taaout in conjunction with performing Inspection Procedure 71707 and on a sampling basis, verify that tags are properly and clearly marked and located.

g. Material Condition. In conjunction with performing Inspection Procedure 71707, observe plant activities, equipment status, and material conditions and evaluate .

their effect on SSCs relied upon to maintain the key safety functions.

h. Corrective Actions. Verify that the licensee's corrective actions program covers shutdown operation.

i. Level of Activity in the Control Room.  !

1. In conjunction with performing Inspection Procedure 71707, verify that outage related activities and traffic in the control room do not interfere with monitoring key safety functions and that adequate control room staffing is maintained.

2. Verify that the remote work center (if applicable) coordinates work activities with the control room operators to ensure that the control room operators are kept cognizant of plant configuration.

J. Instrumentation.

1. Verify that RCS pressure, level, and temperature instruments are installed and configured to pr' ovide accurate indication.

2. Verify that the licensee has assessed and accounted for instrumentation error.

3. Verify that operators have been trained on the results of item 02.02.J.2 and that operators cross-check the instruments when taking readings,

k. Electrical Power.

1. Verify that defense-in-depth (redundancy) is maintained.

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2. In conjunction with performing inspection Procedure 71707, verify that -

i operators and maintenance personnel are aware of the status and l configurations of electrical systems.

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3. Verify that the licensee has procedures for temporary or unusual

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l - electrical system configurations and a clear understanding of these procedures.

4. Verify that switchyard work is controlled commensurate with safety.

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1. Soent Fuel Pool Coolina.

1. Verify that the licensee has in place recovery procedures for situations involving loss of spent fuel pool cooling.

2. Verify that spent fuel pool thermal loading is within the plant design basis.

m. DHR System Monitorina.

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1. In conjunction with performing Inspection Procedure 71707, verify that i operators are provided with instrumentation, alarms, instructions, and training for monitoring DHR system performance.

2. In conjunction with performing inspection Procedure 71707, verify that operators are monitoring and are aware of DHR system status and performance. ,

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3. Verify that operators are aware of the potential effects that special test procedures and operations may have on the DHR system. l

4. For PWRs, when the licensee is relying on the steam generators to provide a backup means of DHR by single-phase natural circulation, verify that the licensee has confirmed the viability of this method of cooling.

n. Inventerv Control. In conjunction with perforrning Inspection Procedure 71707, i

1. Verify that the operators are aware of and sensitive to flow paths, configurations, and ongoing activities that can result in a loss of inventory.

2. Verify that installed automatic features (if applicable) and administrative controls to prevent loss of inventory are implemented.

3. If the licensee is relying on gravity feed as a backup method for makeup, verify operator training on this method.

4. If the licensee is relying on low pressure injection for makeup, veriff operator training on this method.

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o. Reactivity Control. *

1. Verify that licensee personnel in the control room and in containment are monitoring reactivity indications and alarms and that these monitors indicate the reactor is suberitical.

2. Verify that fuelloading and unloading, and fuel movement and sequence are controlled by qualified knowledgeable personnel. Any changes to the refueling plan should be analyzed and reviewed by the licensee prior to implementation. Fuelloading should be performed in a manner to maintain coupling between the instruments used for monitoring reactivity and fuel loaded in any location within the vessel.

3. For PWRs, verify that the licensee has identified and implemented appropriate administrative controls on potential boron dilution paths.

4. For PWRs, verify that the licensee is maintaining redundant boration paths.

5. For BWRs, verify that maintenance on control rod drive mechanisms is fully analyzed and controlled.

p. Containment Closure. For PWRs, verify that licensees control containment penetrations when the refueling cavity is flooded in accordance with the refueling operations TSs and can achieve containment closure' at all times. For BWRs, verify that licensees can close secondary containment during the outage.

3. For PWRs only, for the period when the RCS pressure boundary is not intact and/or steam generators cannot be used for heat removal until the refueling cavity is flooded (including reduced inventory and mid-loop operation) use Attachment A for further guidance.

4. Monitorino of Restart Activities. Verify that operators are aware of TSs, license conditions, and other requirements, commitments, and administrative procedures prerequisites that must be met prior to changing modes or plant corifigurations. Verify that the licensee meets the prerequisites prior to such changes in plant configuration or mode.

DETAILED GUIDANCE

• For PWRs containment closure is met if all containment penetrations (including temporary penetrations, the equipment hatch, and the personnel hatch) have a differential capability equal to ultimate pressure or would be expected to remain intact following an accident. Leakage requirements as described in Appendix J are not a concern. Results from the RES Surry shutdown PRA show that containment pressure (in a sub-atmospheric containment) following a core damage event at shutdown can be high.

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1. Prior to the outaae and in consultation with a Senior Reactor Analyst. revit ytthe licensee's outaae olan

1. No further guidance. l

. .2.

• Defense-in-depth should be maintained during activities identified in item 02.01.a.1.

• Backup SSCs should be identified for those taken out of service when removal of the SSC from s?rvice affects a key safety function.

o Risk of overlap or potential ove:iap of activities should be considered.

• The outage contro process should revent conflicting activities or siraultaimous activities that cause onnecessary risk. (This applies to the outage plan, emergent wod, sand cases where scheduled time is exceeded.)

• The outage control process should consider handling of heavy ir r9. sn' folding crection and the increased potentini for a fire or intsi.9 flood.

3. No further guidance.

4. The outefje plan should be rr. viewed by knowledgeable personnel from the probabilistic assessmer. group, operations, me;.Menance, engineering, training, and licensee management to ensure that safety goals, defense .e-depth, and other expectations and precautians are addressed and achievable, independent review should be performed when practical.

2. Licensee Control of Outaae Activities.

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a. Procedures.

• The licensee should have normal and off-normal procedures that cover:

- DHR:

e The licensee should have procedures for recovery from a loss of DHR and for venting the DHR system if necessary.

Operators thould be knowledgeable of th:; . ant paths and locations of components required for venting the DHR system, o Backup DHri, . .. hods should be priorifized.

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o Operators should be aware of the effects of elevated sections in the DHR suction lines on recovery efforts.

Lower pressure in the elevated sections can result in a loss of single phase in the suction piping which can prevent water from reaching the pumps.

- Upon loss of DHR, procedures should lead operators to the cause of the problem prior to starting other DHR pumps. Immediate start of a second pump could lead to loss of both pumps due to a common cause such as vortexing if level in the RCS is low.

- Containment controlincluding closure of containment and open penetrations. Containment closure procedures should account for potential system unavailability (such as loss of AC power) and containment environmental conditions (such as steam). For ,

BWRs, the licensee should be able to close secondary )

containment during the outage.

- Intentional RCS draining or potential RCS draining due to ongoing activities including monitoring of RCS parameters and receiving tenk levels for operations involving deliberate draining of the RCS.

Cross hecks of amount of inventory drained and that collected in the receiving tanks should be implemented.

- Reactivity control.

• Procedures should account for time available for completion based on time to boiling, time to core uncovery, and RCS configuration. Time to boiling and core uncovery calculations should be current or bounding with respect to decay heat loads and RCS level. Note that loss of inventory could lead to boiling sooner than loss of DHR.

o Operators are trained on the above procedures and are aware of the time available for completion of the procedures.

• Equipment (normal, backup, tempor'ary, etc.) for the above procedures are avail 6ble and operators are trained on the use of such equipment.

b. TSs and Other Rebuirements.

1. No further guidance.

2. No further guidance,

c. Defense-in-Deoth. When equipment is taken out of service for maintenance:

e Equipment should be returned to service in a timely manner.

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• Criteria for declaring an SSC available'should be consistent with the SSC's functional requirements.

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• l Operators and outage control personnel should be aware of which l equipment is relied on for the key safety functions. This extends to the containment sump (PWRs) or the suppression pool (BWRs), and  ;

associated water flow paths.

• The work packages on the equipment being removed from service should i annotate the correct functional equipment group.

• Equipment designated to perform a key safety function should not be adversely impacted by outage activities.

• Maintenance personnel working near operable equipment should be l aware of the reliance on the equipment and the need to not impact it.

• Temporary equipment and tools (cables, hoses, welding, machines, etc.)

near operable SSCs or SSCs providing a key safety function should be adequately controlled to not impact such SSCs.

• Contingency p4ns for restoring key safety functions if lost should be available. Contingency plans should include a prioritization of equipment l to use.

d. Oversicht of Work.

1. No further guidance.

2. Contract personnel must conform to equivalent requirements as do plant personnel. Contract personnel who work directly for regular plant staff i i

supervisors are subject to oversight under the facility's established quality assurance program. However, the facility may also contract with outside vendors to complete specific tasks and to provide their own quality assurance program. In those cases, the facility must verify that the contractors have an adequate quality assurance program. Ensure that the facility has audited the contractor's quality assurance program and that the facility has determined that the contract personnel are following their own quality assurance requirements.

e. Emeroent Work or Unexpected Conditions.

• Determine if licensee procedures or operator training in response to emergent work and unexpected conditions take into account the associated effect on key safety functions, including the consideration to stop work.

Per GL 88-17, Avail ble means ready for use quickly enough to meet the intended functional need. Though the GL was applicable only to PWRs, this definition applies to all plants.

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• Control room operators should be kept informed of plant configuration and response time to certain high risk potential transients (e.g., loss of DHR, loss of inventory), availability of key safety systems and equipment, and changes to plant risk state.

• Emergent work (maintenanec, surveillance, etc.) or planned work which exceeds scheduled tima windows should be controlled to prevent overlap with other activities when such overlap can potentially perturb the plant or affect a key safety function.

• Risk assessments should be maintained current with respect to emergent work and schedule changes.

• Emergent work should be authorized by the outage control point, coordinated with control room operators, and implemented in accordance with established controls and procedures.

e Changes to or deviations from the outage schedule should be implemented in accordance with plant procedures and should ensure that such changes do not adversely impact any key safety function.

Licensees should assess overlapping or potentially overlapping activities s...J th: cffs::ts of these activities on the key safety functions.

f. Taaout. Tags should be property and clearly marked and located and personnel should clearly identify tags with SSCs and cross reference SSCs with work orders prior to taking the SSCs out of service. Personnel should also clearly identify tags with SSCs they are attached to and cross reference tags with work orders prior to any work on the associated SSCs.

g. Material Condition.

• Evaluate operator work-arounds, procedure re-writes, control room deficiencies, temporary modifications, and component failures that result in or are identified from plant transients or an unplanned degradation of a key safety function. ,

e Identified conditions should not impact equipment qualification, seismic qualification, Appendix R requirements, minimum wall thickness, pressure boundary integrity, structural integrity, or other considerations of the ability of the SSC to perform its function. This should include an assessment of potential hazards such as fire, flooding, etc. The inspector should refer to IP 64704 for guidance on fire protection issues.

• Conditions identified should not indicate a concem w?h the skill-of-the-craft (e.g., unacceptably high rework rate of an SSC).

h. Corrective Actions. Events, including those that result in loss of defense in-depth or a key safety function, should be adequately investigated and addressed prior to the next outage and lessons learned should be incorporated into the planning of 9

the next outage. The licensee should also incorporate lessons learned and insights gained from industry experience.

1. Level of Activity in the Control Room.

1. - - - No further guidance.

2. No further guidance.

J. Instrumentation.

1. RCS pressure, level and temperature instruments and associated components (including piping, RCS and connected system vents, etc.)

should be installed and configured to provide accurate indication.

Independent instrumentation for each parameter should be provided to minimize the potential for common cause failure.

e For pressure instruments, operators should be aware that an unexpected increase of pressure may be an indication of an increase in temperature at saturation conditions.

e For isvelinstruments:

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- tubing runs should not have elevation changes that could trap either liquid or vapor / gas in the instrument lines (i.e., loop seals).

-lines should be flushed to ensure single phase in areas dependent on single phase for correct indication.

- temporary installations should be walked down immediately before use and periodically during use.

- operators should be aware of the effect of loss of DHR on the plant's level instrumentation due to heatup and preisurization.

Presser!:ation can lead to false indication of higher level when the referc ce leg is connected to a location that does not sense the pressure increase.

- operators should betrained on the above scenarios and should not remove or fail to add water under false indication of level.

e For temperature instrumentation:

- Instrumentation should be configured to provide an indication representative of the coolant at the core exit. The licensee should -

be aware of the effect of measuring temperature at locations other  !

than the core exit if such a configuration is used. A temperature difference may exist between the instrument reading and the core exit. Additionally. core wide variations in temperature at the core exit may not be provided by such indication. The licensee should 10

have a clear understanding of the temperature distribution across the core even though it may not be measure::.

- Operators should be aware of the effect of loss of DHR on the plant's temperature indication and the potential for discrepancies between the temperature indications and the actual plant state.

Temperature may be measured in the DHR loop in which case interruption, by,.uss, or partial bypass of DHR flow could lead to incorrect and non-conservative temperature indications.

e For allinstruments:

- Controls on instrument line root valvos and work activities in the vicinity of these valves should be implemented.

- Instruments should be calibrated for the conditions of use.

2. e instrument error analyses should have been performed and sources of errors should have been identifed.

e Potential differences between actual and indicated values due to

. Instrume ..etion error, RCS dynamic behavior, and failure to sense the des ad variabl. should be incorporated into operator inst.uctions to take action (i.e., limits, retpoints, etc.).

3. No further guidance.

k. Electrical Power.

1. Three AC power sources, including ene onsite and one offsite, should be maintained. Availability instead of operability of equipment may be acceptable.

2.

• Pre-job briefings for activities near electrical equipment should include precautions to minimjze the impact of the activities on the equipment.

• DC equipment required for operability of electrical and other SSCs relied upon for providing key safety functions should be maintained operable.

3. e Equipment for temporary ir.stallations should be available and staged as necessary.

• Personnel should have been trained on the temporary installations and procedures.

4. The licensee should maintain controls commensurate with safety to preclude hazards and vulnerabilities from being created from ongoing l work. Switchyard work should be controlled and procedures for entering i 11

f' and performing work in the switchyard should be communicated to plant personnel.

1. Soent Fuel Pool Coolina.

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• Recovery procedures based on current / bounding heat loads should exist for situations involving loss of spent fuel pool cooling.

• Operators should be trained on backup equipment and procedures for spent fuel cooling.

• Equipment designated in the recovery procedures should be readily available, dedicated, not obstructed by outage activities, and compatible with equipment that it must be connected to.

e instrumentation, alarms, equipment, instructions, and training should be provided to alert operators for the need and enable I

them to add water to the spent fuel pool if it becomes necessary.

2. No further guidance.

,, m. DHR System Monitorina.

1. Instrumentation, alarms, instructions, and training should exist to enable operators to monitor DHR system performance. These may include indications, alarms, and training on motor current, pump noise, pump flow rate, suction pressure, pump differential pressure, temperature on each side of the DHR heat exchanger, component cooling water (CCW) flow rate, CCW temperature on each side of the DHR heat exchanger, etc.

Pump motor current and noise may be the most sensitive early indications of a problem.

2. No further guidance.

3.

• Guidance should be provide'd in the procedures to minimize the impact of the test / operation on the DHR function.

• Water level vs. flow rate vortexing correlations should be provided for tests / operations involving reduced level in the suction source for the DHR pumps (e.g., hot legs) and operators should be trained on such correlations.

4. For PWRs, when the licensee is relying on the steam generators to provide a backup means of DHR by single phase natural circulation *:

' Single-phase natural circulation should not be relied upon to maintain the plant in cold shutdown condition since boiling in the steam generators will take place resulting in primary system temperatures above the cold shutdown mode definition.

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e Procedures for these methods should be derived from analyses'.

e Operators should be trained on these methods of cooling and the conditions required for them to be achieved.

e The RCS pressure boundary should be closed.

e The steam generator tubes should be full.

e Pressure control capability in the RCS should be maintained to ensure subcooling margin can be maintained.

• Capability to feed the steam peaerators should be maintained.

e Capability to remove steam from the steam generators (e.g., atmospheric relief valves, condenser with steam dump capability, etc.) should be maintained.

n. Inventory Control.

1. Exarnples of loss of inventory paths include DHR to suppression pool on BWRs; main steam line paths including SRV removal, automatic depressurization system testing, main steam isolation valve maintenance, etc. on BWRs; DHR system cross tie valves for PWRs; and maintenance activities on connected piping or components that are at an elevation lower than the vessel flange on c!I plants. For activities on these or other SSCs that could result in loss of inventory:

• The licensee should maintain proper control of work on' piping or SSCs that could result in draining the RCS.

• Personnel should be trained'on the potentia! for draining during maintenance, e Work procedures should include precautions and proper sequence of steps to prevent loss of inventory.

e Work activities requiring freeze seal installation should include continuous monitoring of the freeze seal and contingency pirns should be implemented in case of seal failure.

5 NUREG-1410 Conoseal flow area information is incorrect. Actual flow area is a factor of 20 larger. Consequently, unsealed Conoseals can allow a significant inventory loss rate, yet not provide sufficient venting for pressure control.

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• The licensee should be aware of the potential reduced time to boiling / core uncovery ano adequate instructions, equipment, and training should be provided to mitigate such an event.

2.

• For BWRs, automatic isolation on low level should riot be disabled. This signal can mitigate a loss of inventory from the DHR system to the suppression pool. Maintaining this signal operationalis required by some TSs.

• For BWRs, main steam line plugs should be considered for work activities on the main steam system.

• Reactor cavity seal should be inspected and maintained to preclude potential seal failure. Systems required for proper operation of the reactor cavity seal (e.g., instrument air) should also be maintained to prevent failure of the seal.

3. Adequate vents should be provided to accomplish gravity feed when relied upon.

4.

• Adequate vents should be provided to accomplish low pressure makeup when relied upon.

• For BWRs only, SRV operability should be maintained until the head is removed in order to provide venting for low pressure makeup.

o. Reactivity Control.

1. No further guidance.

2. No further guidance.

3. For PWRs, the licensee should identify and implement appropriate adm:nistrative controls on, potential boron dilution paths. Uniform RCS boron concentration is important, therefore, e lition of water with a lesser boron concentration or starting of reactor coolant pumps which could inject water with a lesser boron concentration into the core should be controlled.

4. No further guidance.

5. No further guidance.

p. Containment Closure. No further guidance.

- 3. No further guidance.

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4. Monitorino of Restart Activities. I I

e Perform a review of a sampling of pre-requisites ensuring that TS Limited Conditions for Operations (LCOs), TS Surveillance Requirements and commitments have been incorporated into mode change authorization documents. -

e Perform independent walkdowns of select safety and risk important (those with a risk achievement worth greater than 2) systems confirming proper system (mechanical, instrumentation, and electrical) alignment.

Ensure outstanding outage activities do not adversely impact systems that have been retumed to service.

e Review a sampling of outstanding work requests, outstanding post maintenance tests, and outstanding post modification tests to ensure the activities do not adversely impact key safety functions presently required or systems presently retumed fio service and required in the next mode, e Review a sampling of completed tests to confirm the test results recorded met the established acceptance criteria and the surveillance schedule for overdue tests.

e Review a sampling of equipment tagging 'ogs, jumper and lifted wire logs, caution tag logs and temporary modification logs to ensure the activities do not adversely impact key safety functions presently required or systems presently retumed to service and required in the next mode.

e Confirm all pre-requisites v. e signed as completed after the mode change occurred. Any excepm were appropriately approved in accordance with procedure char.p administrative controls.

REFERENCES GL 88-12,' Loss of Residual Heat Removal (RHR) While the Reactor Coolant System (RCS)is Partially Filled,' July 9,1987. ,

NUREG-1269,

• Loss of Residual Heat Removal System, Diablo Canyon, Unit 2, April 10,1987,*

June 1987. .

Region i Temporary Instruction 88-02 (NRC Region I)," Loss of Decay Heat Removal Capacity when Reactor Coolant System Partially Drained,' March 18,1988.

GL 88-17, " Loss of Decay Heat Removal,10 CFR 50.54(f)," October 17,1988.

Tl 2515/101, " Loss of Decay Heat Removal (Generic Letter No. 88-17) 10 CFR 50.54(f),"

February 16,1989.

Tl 2515/103," Loss of Decay Heat Removal (Generic Letter No. 88-17) 10 CFR 50.54(f),

Programmed Enhancements (Long Term) Review,' December 18,1989.

NUREG-1410,' Loss of Vital AC Power and the Residual Heat Removal System During Mid-15 b

l l I

f Loop Operations at Vogtle Unit 1 on March 20,1990," June 1990.

l Ti 2515/113, " Reliable Decay Heat Removal During Outages," November 18,1991.

NUMARC 91-06," Guidelines for Industry Actions to Assess Shutdown Management," Nuclear

. Management and Resources Council, Inc., Demmber 1991.

NUREG-1449, ' Shutdown and Low-Power Operation at Commercial Nuclear Power Plants in i the United States," September 1993.

IN 93-72, " Observations from Recent Shutdown Risk and Outage Management Pilot Team l l Inspections," September 14,1993.

Memorandum to Robert C. Jones, Chief, Reactor Systems Branch, from Michel Labatut and Mohammed A. Shunibi,

• REVIEW OF RECENT SHUTDOWN EVENTS," November 28,1995.

4 i

. Regional Office Instruction No. 2216, Rev.1 (NRC Region 11)," Review of RCS Mid-loop / Reduced inventory Activities," December 28,1995.

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l PG 9009C (NRC Region IV), " inspection of Mid-loop / Reduced Inventory Activitien," i November 28,1997.

{

l Memorandum to L. Joseph Callan, Executive Director for Operations, from John C. Hoyle,

• STAFF REQUIREMENTS - SECY-97-168 - ISSUANCE FOR PUBLIC COMMENT OF

! PROPOSED RULEMAKING PACKAGE FOR SHUTDOWN AND FUEL STORAGE POOL OPERATION," December 11,1997.

PG 0805 (NRC Region IV),

• Plant Material Condition inspection Guidance," March 26,1998.

Memorandum to DRP Branch Chiefs and Senior Resident inspectors [of NRC Region IV), from Thomas P. Gwynn Director DRP, Region IV, ' OUTAGE INSPECTION PLANS." March 1998.

END Attachment A l

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1 ATTACHMENT A REDUCED INVENTORY AND MID-LOOP OPERATION For PWRs. evaluate Licensee Performance when the RCS oressure boundarv is not intact I and/or steam cenerators cannot be used for heat removal until the refuelina cavity is flooded (reduced inventory and mid-looo operation are a subset of this condition),

s. Review licensee resoonses to GL 8817 to determine the olant-soecific inspection criteria to be used in cart b, below. Note that commitments to GL 88-17 may be different for different olanti and may also be different than the information contained in the aeneric le11gr.

b. Prior to entry into reduced inventory:

1. Verify:

• Training is provided to operators prior to entering a reduced inventory condition. Review of lessons leamed from previous events and simulator training is valuable.

• The licensee has clearly established criteria for termination of drain down and for water addition. l

• Operators are aware of the time constraints they're under for completing the procedures. Such time constraints may be a function of time to boll, time to core uncovery, expected environmental conditions due to steam, expected radiological conditions, etc.

2. Verify that calculations of time to boiling / core uncovery are based on the I decay heat load and the expected RCS level after draining to mid-loop.

The licensee should recognize that time to boiling / core uncovery can occur much sooner on a loss of inventory event.

3. Verify that the pressurizer and reactor vessel head are adequately vented'. , )

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4. Verify: i o Redundant equipment, with sufficient capacity, is provided for  !

normal core cooling. j 6

The principle concerns are equalization of pressure between the reactor vessel head and the pressurizer, and prevention of pressure differences that significantly affe' level l i

indication.

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i e instrumentation, alarms, instructions, and training exists to enable operators to monitor DHR system performance. These may include indications, alarms, and training on motor current, pump flow rate, suction pressure, pump differential pressure, pump noise, temperature on each side of the DHR heat exchanger,

.-- CCW flow rate, CCW temperature on each side of the DHR heat exchanger, etc.

• Visible and audible indications in the control room of abnormal conditions in DHR system performance.

e The licensee has defeated the autoclosure interlock or taken some other appropriate action to prevent loss of DHR on isolation-of the DHR suction isolation valves.

5. Verify:

• That the licensee has at least two available or operable means of adding inventory to the RCS in addition to DHR pumps. These should include at least one high pressure injection pump. 'he f makeup rate should be sufficient to keep the core covered.

• Procedures exist for the use of ese systems during a lot,. of DHR invent.

e Paths of water addition are specified to assure the flow does not bypass the reactor vessel before exiting any openings in the RCS.

1 e Adequate RCS venting has been identified to allow for water j addition methods (e.g., gravity feed, low pressure injection) to j keep the core covered. 1

6. Verify that the licensee maintains redundant onsite and offsite power sources available, with sufficient capacity, and that proper controls have been estah'ished to ensure their availability. A minimum of three AC power sources, including a minimum of one onsite and one offsite, should be maintained. Controls may include enhanced switchyard controls, I posting of emergency power sources, etc.

7. Verify:

• The licensee has at least two independent, continuous RCS level, temperature, and pressure indications. Indications should be periodically checked and recorded by an operator or automatically and continuously monitored and alarmed. Temperature indications should be representative of core exit conditions.

e For pressure instruments, verify that operators are aware that an unexpected increase of pressure may be an indication of an increase in temperature at saturation conditions.

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• Instruments are within calibration and that the scale is appropriate for the application.

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-* The licensee has established an allowed deviation value for the l leve! indications being used and identified actions to be taken in  !

the event that the difference between the indications exceeds the allowed deviation.

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The licensee has visible and audible indications in the control room of abnormal conditions in RCS level, temperature, and pressure.

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8. Verify that all hot legs are not blocked simuttaneously by nozzle dams (or loop isolation valves) unless a vent path is provided that is large enough i to prevent pressurization of the upper plenum of the reactor vessel.7 i (applicable to Westinghouse and Combustion Engineering (CE) nuclear steam supply system designs)

9. Wrify that the licensee has procedures and administrative controls to i schieve cont

• ment closure prior to the time at which core uncovery could occur. Containment closure procedures should include consideration of power availability and potential steam and radioactive material release from the RCS. Requirements on number of closure bolts should be established. Equipment should be prestaged and individuals designated for equipment haten closure. Determine whether the licensee is aware of all breaches in containment and has contingency plans to close these breaches.

10. Verify that the licensee has procedures, training, and controls to prevent potential perturbations of the RCS and supporting systems during reduced inventory when decay heat is high. When systems or i

components require lowered RCS inventory for maintenance or testing, '

reasonable attempts should be made to conduct such activities when decay heat is low. "

11. Verify that the licensee has satisfied the prerequisites and initial conditions required by their procedure.

12. Verify:

e For draindown, the licensee has established adequate procedures, identified and made available the necessary equipment, and taken necessary precautions to conduct the evolution in a safe and deliberate fashion.

' The principle concern is more than a few inches of water pressurization if a cold leg is open to containment. If all nozzle dams are in place, the principle concem is likely overpressure of nozzle dams or forcing water out of seal table openings.

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e Activities unrelated to the draindown evolution are minimized and that an environment has been established in the control room I which allows operators to focus on the draindown to minimize i distractions.

o Operators are aware of critical limits such as vortexing limits.

e- Proper management oversight of the draindown evolution has been established and that dedicated watchstanders are stationed as required by the' licensee's procedures.

l e Adequate communications have been established with operators  !

outside of the control room assigned to monitor critical l parameters.

c. While drainina the RCS to reduce inventorv-l 1

1. Verify that the pressurizer and reactor vessel head are adequately i vented.

2. Verify.

• The licensee is utilizing the most conservative indication of RCS level and that operators periodically compare the level indications

. to determine if any unacceptable deviation exists.

e Consideration of level instrument uncertainty in the positive direction is also considered to ensure that the steam generator tubes drain property, e Operators cross check the amount of inventory drained from the RCS with that received by the receiving tanks to ensure that the total inventory is accounted for and that the draindown is continuing in a controlled manner, e Operators'have instructions to stop the draindown operation and take appropriate actions prior to recommencing the draindown in the event that the difference between levelindications exceeds the allowed deviation' established by the licensee. This applies to both reactor coolant level as well as receiving tank level.

3. Verify that temperature and pressure indications are being per!odically checked and recorded by an operator or automistically and continuously monitored and alarmed.

4. Verify that the controls established and reviewed in Section b.12 above

, are adequately controlling the evolution in a safe and deliberate manner.

d. While operatina in a reduced inventory or mid-looo condition with fuel in the reactor vessel 4

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1. Verify that the status of key safety functions is rnaintained current with respect to changing conditions.

l l 2. Verify that the licensee confirms the time to boiling / core uncovery calculations are maintained current or bounding with respect to actual decay heat load and actual level following draindown. -

3. Verify that the pressurizer and reactor vessel head are adequately l vented.

4. Verify that the normal core coohng equipment is properly aligned. Verify that the licensee is monitoring DHR performance whenever the DHR system is being used for cooling the RCS.

t

) 5. Verify that the licensee is maintaining at least two available or operable I

means of adding inventory to the RCS in addition to the DHR pumps.

, 6. Verify that the licensee is maintaining redundant offsite and onsite power

! sources available, with sufficient capacity, and that appropriate controls

! remain in place to ensure their availability. A minimum of three AC power sources, including a minimum of one onsite and one offsite, should be maintm.ad i

7. Verify that the licensee is maintaining two independent, continuous RCS {

water level, pressure, and temperature indications. Confirm that j

indications are periodically checked and recorded or automatically and continuously monitored and alarmed.

8. Verify that the licensee maintains containment penetration status and has j the means to establish containment closure.

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Pbe July 9,1999 To PUBLIC C0CUMENT ROOM The April 7* memo can be released to the public per Mr. Jared Wermiel, Chief, SRXB/DSSA. N JU.l 15 A 7 :21

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170044 TOTAL P.02

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