IR 05000313/1999003

Insp Repts 50-313/99-03 & 50-368/99-03 on 990202-17.No Violations Noted.Major Areas Inspected:Operations

ML20205L782
Person / Time
Site:	Arkansas Nuclear
Issue date:	04/09/1999
From:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV)
To:
Shared Package
ML20205L776	List: IR 05000313/1999003 ML20205L771
References
50-313-99-03, 50-313-99-3, 50-368-99-03, 50-368-99-3, NUDOCS 9904140290
Download: ML20205L782 (19)

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ENCLOSURE U.S. NUCLEAR REGULATORY COMMISSION

REGION IV

Docket Nos.: 50-313 50-368 License Nos.: DPR-51 NPF-6 Report No.: 50-313/99-03 50-368/99-03

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Licensee: Entergy Operations, In Facility: Arkansas Nuclear One, Units 1 and 2 j Location: Junction of Hwy. 64W and Hwy. 333 South Russellville, Arkansas 72801

Dates: February 2-17,1999 inspector: K. Kennedy, Senior Resident inspector Approved By: Charles S. Marschall, Chief, Project Branch C Division of Reactor Projects ATTACHMENTS: Supplemental Information l

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9904140290 990409 PDR ADOCK 05000313 G PDR ,

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EXECUTIVE SUMMARY Arkansas Nuclear One, Units 1 and 2 NRC Inspection Report No. 50-313/99-03; 50-368/99-03 On Februsry 2,1999, licensed operato,*s, lowering the refueling canal level to allow installation of the reactor vessel head, inadvertently drained the reactor vessel to reduced water inwntory conditions. This special inspection was conducted to evaluate the circumstances surrounding the event. The results of this inspection indicated that your procedures and training were not adequate to safely lower the level in the Unit 2 refueling canal to the top of the reactor vesse A procedure error, inadequate procedural controls, operator error, and inadequate training reflected a lack of recognition of the potential hazards associated with lowering the water level in the refueling canal. As a result, water level was lowered in the reactor vessel at an unintentionally high rate. Rapid operator action was requiwd to ensuc e that the water level in the reactor coolant system (RCS) remained sufficient for the proper operation of the shutdown cooling system. However, licensee engineers evaluated the risk significance of the event and concluded that the event was of minimal safety significance. This conclusion was based on the multiple sources of makeup water available, the high level of mitigation equipment redundancy ;

and diversity, and the quick operator identification of and response to the even i Operations

The precettions, limitations, and instructions contained in Procedure 2102.015, Revision 10-01," Filling and Draining the Refueling Canal," did not reflect the I significance or potential consequences of draining the refueling canal to the top of the reactor vessel. Procedure writers had not developed a graduated transition from the limited controls described in this procedure and the implementation of extensive controls for draining the RCS contained in Procedure 2103.011. As a result, operators had little merin for error in the transition from draining the refueling canal to draining the reactor vessel. Additionally, Procedure 2102.015 was inadequate because it provided an incorrect value of 90 inches for the reactor vessel flange. This incorrect information directly resulted in operators inadvertently entering reduced inventory conditions by draining the reactor vessel to a level of 56 inches above the bottom of the hot leg. The inadequacy of this procedure was identified as a noncited violation of Technical Specification 6.8.1 (Section 03.1).

The control room supervisor conducted a weak prejob briefing prior to draining the refueling canal. The prejob brief did not comply with the guidance in the licensee's administrative procedures or meet management expectations. The control room supervisor did not require the participation of all personnel with evolution responsibilities and did not cover topics such as lessons learned, previous performances of the evolution, or contingency actions. A formal briefing as described in the conduct of oparations procedure was a potential barrier to this event that was not implemented (Section O3.2).

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Procedure 2102.015 was inadequate because the task to lower the refueling canal water level to the top of the reactor vessel was not classified as an infrequently

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-2-performed test or evolution (IPTE). The procedure writer's failure to classify the task as an IPTE, resulting in a failure to implement the additional controls, was identified as a noncited violation of Technical Specification 6.8.1 (Section 03.2).

• Operators failed to correctly implement Procedure 2102.015 by not stationing an operator to monitor water level while draining the refueling canal. This was identified as a noncited violation of Technical Specification 6.8.1 (Section 04.1).

Operators closely monitored !svel while draining the refueling canal. They quickly recognized that the RCS level was decreasing rapidly and took appropriate actions to stop draining and refill RCS with a high-pressure safety injection pump. However, the operators' decision to fully open Valve 2SI-18 to drain the refueling canal increased the time required to stop draining the reactor vessel and contributed to the inadvertent entry into reduced inventory. The control room supervisor was unaware that the valve required 55 turns to close the valve from the full open position, and the shift superintendent was unaware that the valve was fully opened (Section O4.2).

• Operators were generally unaware of the critical RCS levels associated with draining the refueling canal to the top of the reactor vessel. The training provided to operators on draining the refueling canal was inadequate (Section 05.1).

• Licensee engineers evaluated the risk significance of the inadvertent reactor vessel draining and concluded that it had minimal safety significance. This conclusion was based on the multiple sources of makeup water available, the high level of mitigation I equipment redundancy and diversity, and the quick operator identification of and response to the event (Section 08.1).

• The licensee's event investigation team conducted a thorough, probing review of the inadvertent entry into reduced water inventory conditions, identified valid root and contributing causes, and proposed a number of corrective actions that address all of the causes identified (Section 08.2).

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Report Details Summary of Plant Status During this inspection, Unit 1 operated at 100 percent reactor power. Unit 2 was shutdown for Refueling Outage 2R1 I. Operations

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01 Conduct of Operations i

O Unit 2 - Event Description and Chronoloav of Transient (71707)

On February 2,1999, Unit 2 was in Day 24 of Refueling Outage 2R13. Refueling was J complete, the reactor vessel head was removed, steam generator nozzle dams were ;

installed, and the borated water level in the refueling canal was at 397 feet l

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7 inch elevation. This correlated to an instrument level of 341.8 inches with instrument zero being the bottom of the hot leg. Low-Pressure Safety injection Pump 2P-60B was i in service providing shutdown cooling flow for the RCS. Unit 2 operators were preparing !

to lower the water level in the refueling canal to allow installation of the reactor vessel hea i Control room operators began draining the water from the refueling canal at 2:20 using Procedure 2102.015, Revision 10-01, " Filling and Draining the Refueling Canal."

The procedure allowed the use of one or two low pressure safety injection sydem pumps to pump water from the RCS to the refueling water tank, An auxiliary operator established the flow path to the refueling water tank by opening Valve 2SI-18, a Ginch manual globe valve, to a throttled position. Once the drain rate was established, the control room supervisor directed a control room operator to start a second low-pressere safety injection pump and directed the auxiliary operator stationed at Valve 2SI-18 to fully epan the valve. In this configuration, the rate of level decrease was approximately 3.3 inches per minut Operators stopped draining the refueling canal at 3:37 p.m., when the level was at 137 inches above the bottom of the hot neg, to obtain a refueling canal water sample for boron analysis as required by procedure. Operators recommenced draining the canal at

, 4:06 p.m. using two low-pressure safety injection pumps and fully opening Valve 2SI-1 Procedure 2102.015 directed operators to stop draining the refueling canal when the water level was even with the reactor vessel flange. The procedure erroneously indicated that the vessel flange was at a level of 90 inches. However, the reactor vessel flange was located at 100.5 inche Operators planned to control their approach to the 90-inch level. When the level was at 105 inches, the control room supervisor directed the auxiliary operator to begin closing Valve 2SI-18. Immediately after the control room supervisor directed that Valve 2SI-18 be throttled closed, the control board operator - reactor reported that RCS level was decreasing rapidly. The control board operator stopped one low-pressure safety injection pump, and the control room supervisor directed the auxiliary operator to quickly close Valve 2SI-18. Because it took approximately 55 turns on the valve handwheel to

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-2-i fully close Valve 2SI-18, there was a delay of approximately 1.5 minutes until the valve was fully closed. By the time the refueling canal draining was stopped, RCS level had decreased to 56 inches, well below the 65-inch level defined as RCS reduced inventory conditions. Operators started a high-pressure safety injection pump and raised RCS level to 90 inches. The RCS was in a reduced inventory condition for approximately 7 minutes. Licensee personnellater determined that the average rate of level drop from 105 inches to 56 inches was 33 inches per minut A detailed chronology of the event is described in Attachment 2 to this inspection repor Operations Procedures and Documentation O3.1 Unit 2 - Procedure Error Resultina in inadvertent E.ntrv Into Reduced Inventory Inspection Scope (71707)

The inadvertent entry into reduced water inventory conditions in the RCS on February 2 was described in Section 01.1 of this inspection report. Unit 2 operators used Procedure 2102.015, Revision 10-01, * Filling and Draining the Refueling Canal," to drain the refueling canal on February 2. The inspector reviewed the procedure to assess the accuracy and adequacy of the instructions provided to the operators for performing the evolutio Observations and Findinas The inspector found that there were several key refueling canal water levels relevant to draining the refueling canal. The actuallevel of the reactor vessel flange is approximately 100.6 nches. There is a permanent reactor vessel cavity seal plate installed that surrounds the reactor vessel and extends above the reactor vessel flang The level at the top of this seal plate, referred to as the RCS overflow to refueling canal I level, is approximately 106 inches. At the start of the evolution to drain the refueling canal, there was a significant volume of water in the canal to draw from, and the decrease in level was relatively low. However, as the water level in the canal reached the top of the seal plate, the surface area of water was significantly reduced to that of the reactor vessel. Thus, the decrease in water level significantly increased, while the drain rate in gallons per minute remained relatively constant, once the water level reached the top of the seal plat Procedure 2102.015 provided the Unit 2 operators instructions for filling and draining the refueling canal. Section 7," Pumping the Canal Down to the Reactor Vessel Flange Level," provided instructions for lowering the level in the refueling canal to the reactor vessel flange. Step 7.2.15 stated "When refueling canallevel reaches desired elevation or level is even with reactor vessel flange (90 inches), then stop draining . . . ."

Following the event, the licensee determined that the level of 90 inches for the reactor l vessel flange was incorrect. As discussed above, the actuallevel of the reactor vessel flange is approximately 100.5 inche i

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-3-The inspector also found that Procedure 2102.015 provided limited detail on how to perform the evolution and lacked precautions and limitations commensurate with the potential consequences of the *sk. For example, the procedure did not provide j precautions or limitations on ; use of two low-pressure safety injection pumps or the appropriate position of Valve 2SI-18 to drain the refueling canal. Additionally, the inspector found that the procedure did not provide for a graduated transition from the limited controls for draining the refueling canal provided in Procedure 2102.015 to the j implementation of extensive controls for draining the RCS contained in l Procedure 2103.011," Draining the Reactor Coolant System." As a result, there was little margin for error in the transition from draining the refueling canal to draining the reactor vesse '

During the draining evolution on February 2, operators stopped draining the refueling canal at 137 inches to obtain a water sample far boron analysis. Operators began to stop draining the canal at 145 inches,8 inches above the desired level, when the control room supervisor directed operators to close Vaive 2SI-18 and stop Low-Pressure Safety injection Pump 2P-60A. This worked wellin establishing the desired water level. Based on this success, the control room supervisor decided that the same method would be used to estab9h the water level at 90 inches. Once the results of the boron sample were obtained, me drain was recommenced using two low-pressure safety injection pumps and with Valve 2SI-18 fully or m At a level of 105 inches, the control room supervisor directed an operator to begin l closing Valve 2SI 18. At the same time, the reactor operator noted a rapid increase in i the rate that level was decreasing and reported this to the control room supervisor. This sudden increase was due to the fact that water level had dropped below the top of the seal olate, approximately 106 inches, and the two low-pressure safety injection pumps were pumping at the same rate but from a much smaller volume of wate The intent of Procedure 2102.015 was to drain the refueling canal to the RCS spillover

, level of approximately 106 inches. If further draining was desired, Attachment B

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directed the use of Procedure 2103.011," Draining the Reactor Coolant System."

Step 7.2.15 should have directed operators to stop draining the refueling canal at a level greater than or equal to 106 inches. Instead, it directed operators to lower level to 90 inches. This error directly resulted in operators inadvertently entering reduced inventory conditions by draining reactor vessel to a level of 56 inches above the bottom of the hotle The inspector reviewed previous revisions of Procedure 2102.015 and found that the incorrect value of 90 inches was added to the procedure in March 1994 by Procedure Change One 1 to Revision 5. Prior to this change, the procedure did not provide a numerical value for the level of the reactor vessel flang Procedure 2102.015, Revision 5, step 7.2.8, directed operators to stop the draining operation when " water level is approximately even with the reactor vessel flange." A numerical value was not included in the procedure prior to March 1994 because there was no reliable level indication that could be used to monitor refueling canal level from the control room. Levelinstrumentation was installed in Refueling Outage 2R9 in November 1992 and first utilized in Refueling Outage 2R10. Prior to installation of the

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level instrumer:tation, operators relied solely on visual observation of refueling canal level to determine when level approached the top of the reactor vessel flang Neither the inspector or the licensee were able to determine why the incorrect level of 90 inches was used in the 1994 procedure change. As discussed in Section 05.1, the inspector found that operators did not know tha proper level for the reactor vessel flange. Operators believed that the reactor vessel flange leml and the head removal level were both at the 90-inch level. Additionally, they did not consider the level at the top of the seal plate in conducting the drain evdution. This misconception and lack of knowledge of the actual reactor vessel flange level may have caused the wrong value to Se introduced to the procedure in 199 Unit 2 Technical Specification 6.8.1 requires, in part, that written procedures shal! be established, implemented, and maintained covering the applicable procedures recommended in Appendix A of Regulatory Guide 1.33, Revision 2, February 197 Regulatory Guide 1.33, Appendix A, Section 3.a, states, in part, that instructions for energizing, filling, venting, draining, startup, shutdown, and changing modes of operation should be prepared for the RCS. Section 9.d.(4) states, in part, that procedures that could be categorized either as maintenance or operating procedures should be developed for draining and refilling the reactor vessel. The inspector determined that Procedure 2102.015, Revision 10-01, " Filling and Draining the Refueling Canal," was inadequate in that step 7.2.15 provided an incorrect value of 90 inches for the reactor vessel flange, the level at which draining of the refueling canal was to be stopped. As a result, operators inadvertently entered reduced inventory conditions by draining reactor vessel to a level of 55 inches above the bottom of the hot leg. This is a violation of Technical Specification 6. This Severity Level IV violation is being treated as a noncited violation, consistent with Appendix C of the NRC Enforcement Policy. This violation is in the licensee's corrective action program as Condition Report 2-1999-197 (50-368/9903-01).

c. Conclusions The precautions, limitations, and instructions contained in Procedure 2102.015, did not reflect the significance or potential consequences of draining the refueling canal to the ,

top of the reactor vessel. Procedure writers had not developed a graduated transition I from the limited controls described in this procedure and the implementation of I extensive controls for draining the RCS contained in Procedure 2103.011. As a result, operators had little margin for error in the transition from draining the refueling canal to draining the reactor vesse AdJitionally, Procedure 2102.015 was inadequate because it provided an incorrect value l of 90 inches for the reactor vessel flange. This incorrect information directly resulted in

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operators inadvertently entering reduced invento:y conditions by draining the reactor vessel to a level of 56 inches above the bottom of the hot leg. The inadequacy of this )

procedure was identified as a noncited violation of Technical Specification 6. l

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l 5-O3.2 Unit 2 - Refuelina Canal Drain Task Not Identified as an IPTE l Insoection Scone (71707)

The inspector reviewed the preparations that were made by the control room operators l prior to commencing the draining of the retueling canal. The inspector reviewed l Procedure 2102.015, Revision 10-01, " Filling and Draining the Refueling Canal," to l

determine if the task to drain the refueling canal incorporated the appropriate controls established by Procedure.1000.143, Revision 4, " Control of infrequently Performed Tests or Evolutions."

l Observations and Findinas Prior to beginning the evolution to drain the refueling canal, the control room supervisor l conducted a prejob briefing with control room operators. Personnel attending the l briefing included the control room supervisor, control board operator - reactor, control board operator - turbine, and the waste control operator. The shift superintendent was present for only portions of the briefing. The briefing included a discussion of how the draining evolution was going to be conducted, including stopping at a level of 137 inches to obtain a refueling canal water sample for boron analysis. The procedure required an operator to be stationed in the plant during the evolution to operate Valve 2SI-18 and an individual to monitor the level in the spent fuel pool. During the briefing, the control room supervisor decided to station a dedicated operator, rather than the on-watch waste control operator, to operate Valve 2SI-18. This operator, and the individual to be stationed at the spent fuel pool, received individual briefings from the control room supervisor and did not participate in a briefing with all of the participant The inspector reviewed guidance contained in Procedure 1015.001, Revision 51,

" Conduct of Operations," regarding the conduct of prejob briefings. Section 15,

" Departmental Interfaces," stated that "!f an activity _iji non-routine, very complex in

, nature and/or multi-craft or multi-organization, a pre-job briefing may be needed to i

ensure safe performance of the activities." Section 18,' Briefing Guidelines," stated that crew briefings should be held for off-normal or complex tests or evolutions. The procedure stated that crew briefings shall involve all individuals participating in the test or evolution and referred operators to Form 1015.001D, " Crew Brief Checklist," to ensure that an adequate briefing is performed. The checklist provided topics to be covered during the briefing, including lessons learned, previous performances of the evolution, sequence of events, limits and precautions, contingency actions, impact to overall safety, parameters which required monitoring and expected response, specific individual duties, and any abnormal operating procedures that might be require Although a briefing was conducted prior to the start of the evolution, the briefing did not use Form 1015.001D " Crew Brief Checklist." While some of these topics were discussed prior to the evolution, the briefing was informal and did not include all participants at the same time. The licer.see stated that the prejob briefing did not meet the guidance of Procedure 1015.001 and did not meet management expectations. The

-6-licensee determined that the prejob briefings for draining the refueling canal during Refueling Outages 2R11 and 2R12 were more formal and included the appropriate topics listed on Form 1015.001D.

The inspector concluded that the conduct of a formal briefing as described in the Conduct of Operations procedure was a potential barrier to this event that was not implemented by operators.

The inspector also found that, although Procedure 2102.015, Revision 10-01, " Filling and Draining the Refueling Canal," was classified as an IPTE, this classification did ne*

apply to Section 7, " Pumping the Canal Down to Reactor Vessel Flange Level."

l Procedure 1000.143, Revision 4, " Control of infrequently Performed Tests or I Evolutions," defined an IPTE as an infrequently performed activity that has the potential to significantly degrade nuclear, radiological, or personnel safety and/or equipment / plant reliability. Activities classified as PTE required additional controls intended to prevent unanticipated problems from occurring that could result in degradation of any margins of safety. These additional controls included increased management oversight of the l activity and a formal prejob briefing using Form 1000.143C,"lPTE Crew Brief Checklist."

Items to be discussed during the prejob briefing included: '

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The reason that the activity was classified as an IPTE and the potential consequences associated with personnel error,

• The expected plant response,  !

• An emphasis on human performance improvement tools to be used at critical I points in the evolution, a Potential problems and associated contingencies, and

= Industry and site-specific lessons learned, including cause of previous events and barriers to prevent occurrenc ,

The inspector determined that draining the refueling canal to the top of the reactor vessel, as described in Procedure 2102.015, Section 7, was infrequently performed and had the potential to significantly degrade nuclear, radiological, and/or equipment / plant reliability. As a result, Procedure 2102.015 was inadequate because this task was not classified as an IPTE. Classification of this task as an IPTE may have prevented the unanticipated draining of the RCS into reduced inventory conditions.

Unit 2 Technical Specification 6.8.1 requires, in part, that written procedures shall be established, implemented, and maintained covering the applicable procedures recommended in Appendix A of Regulatory Guide 1.33, Revision 2, February 1978.

Regulatory Guide 1,33, Appendix A, Section 3.a. states, in part, that instructions for energizing, filling, venting, draining, startup, shutdown, and changing modes of operation should be prepared for the RCS. Section 9 d.(4) states, in part, that procedures that could be categorized either as maintenance or operating procedures

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-7-should be developed for draining and refilling the reactor vessel. The failure to classify the task as an IPTE, resulting in a failure to implement the additional controls described in Procedure 1000.143, is a violation of Technical Specification 6. This Severity Level IV violation is being treated as a noncited violation, consistent with Appendix C of the NRC Enforcement Policy. This violation is in the licensee's corrective action program as Condition Report 2-1999-197 (50-368/9903-02). j Conclusions The control room supervisor conducted a weak prejob briefing prior to draining the refueling canal. The prejob brief did not comply with the guidance in the licensee's administrative procedures or meet management expectations. The control room supervisor did not require the participation of all personnel with evolution responsibilities and did not cover topics such as lessons learned, previous performances of the evolution, or contingency actions. A formal briefing as described in the conduct of operations procedure was a potential barrier to this event that was not implemente In addition, Procedure 2102.015 was inadequate because the task to lower the refueling canal water level to the top of the reactor vessel was not classified as an IPTE. The procedure writers' failure to classify the task as an IPTE, resulting in a failure to q implement the additional controls, was identified as a noncited violation of Techriical l Specification 6. ]

04 Operator Knowledge and Performance 1 04.1 Unit 2 - Failure to Folicw Procedure i Inspection Scoce (71707)  !

The inspector reviewed operator's use of and adherence to Procedure 2102.015, Revision 10-01," Filling and Draining the Refueling Canal." Observations and Findinas The inspector found that Procedure 2102.0 ,, step 7.2.9, directed operators to " Station personnelin communication with the control room to monitor Refueling Canallevel."

Contrary to the instructions of this step, the control room supervisor did not station an operator in communication with the control room to monitor refueling canal level during the evolution. Instead, a camera located inside containment, aimed at the refueling canal, provided input to a monitor located in the control room. The control room i supervisor believed that use of a remote camera and monitor satisfied the intent of the , ;

step and did not discuss this with the shift superintendent. Operators had previously l j used remote cameras to monitor other activities inside containment, including removal i

of the reactor vessel head, upper guide structure, core support barrel, and changes to the refueling canallevel. Although the level was displayed on the monitor, an operator i

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8-was not assigned to observe these indications. As a result, operators paid little attention to the monitor. Additionally, the monitor did not provide a clear picture of the water level in the refueling cana The inspector found that previous revisions of the procedure contained specific instructions to station an operator inside the containment building to monitor level during the draining of the refueling canallevel. The current step did not specifically direct that an operator be stationed inside the containment building to monitor level. However, the inspector found that an operator had been stationed inside containment when this evolution was performed during the previous two Refueling Outages 2R11 and 2R12.

l The inspector determined that stationing an individual in communication with the control

! room to monitor refueling canallevel during the evolution was a barrier to this event that was not properly implemented.

l The failure to station personnel in communication with the control room to monitor l refueling canal level while draining the refueling canal to the reactor vessel flange is a

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violation of Technical Specification 6.8.1. This Severity Level IV violation is being treated as a noncited violation, consistent with Appendm C of the NRC Enforcement Policy. This violation is in the licensee's corrective action program as Condition Report 2-1999-197 (50-368/9903-03).

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Operators failed to correctly implement Procr: dure 2102.015 by not stationing an operator to monitor refueling canal level duri1g the evolution. This was identified as a noncited violation of Technical Specification 6.8.1.

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O4.2 ' Unit 2 - Operator Performance and Event Response

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I Inspection Scope (71707)

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in addition to the items discussed in Section 04.1 above, the inspector reviewed operator performance during the evolution and in response to the unanticipated lowering

of the RCS level to midloop condition Observations and Findinas l

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i l Procedure 2102.015 contained a note in Section 7 that stated that the elevations for j l

various refueling maintenance operations were shown in Procedure 2103.011. " Draining  ;

l the Reactor Coolant System," Attachment L. The attachment includd (ne levels for l

RCS overflow to the refueling canal and head removal, but dir' not list the reactor vessel flange level. The inspector found that operators did not refer to the attachment to review the various elevation !

l The inspector found that operators established the drain path to the refueling water tank by fully opening Valve 2SI 18. Although the control room supervisor directed the operator to fully open Valve 2SI-18, he was unaware that it took approximately 55 turns i

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. to close the valve from the full open position. In addition, the shift superintendent was unaware that the valve was fully open. As .a result, when operators recognized the increase in drain rate and began actions to stop draining the system, it took the operator approximately 1.5 minutes to fully close the valve. Following the event, licensee personnel determined that Valve 2SI-18 did not need to be fully opened to achieve the maximum desired drain rat The inspector determined that control room operators established enhanced controls during the evolution and were attentive to RCS level indications. For example, a quiet environment was established in the control room to minimize activities that would distract operators from their duties. In addition, the reactor operator closely monitored RCS water level indications available in the control room and reported the level to the control room supervisor in 10-inch increments. To stop the draining at 137 inches, operators initiated actions to stop at 145 inches, providing an 8-inch margin to the desired level. In draining to a level of 90 inches, the operators decided to add additional margin and begin to stop draining at 105 inches,15 inches above the desired leve Operators quickly identified that the RCS level was decreasing rapidly and took appropriate actions to stop draining and refill the RCS with a high-pressure safety injection pump. Control room operators recognized the potential for a loss of shut down cooling if RCS level continued to decrease and were prepared to stop the remaining low-pressure safety injection pump, if necessary, to stop draining the reactor vesse The inspector reviewed Procedure 2103.011, Revision 24-04," Draining the Reactor Coolant System," Exhibit 1, " Maintenance Levels and SDC Vortex Curve," and found that RCS level had remained above the limits established to prevent vortexing of the shutdown cooling system pumps throughout the event. In addition, shutdown cooling flow to the RCS had been maintained within the required limits and pump parameters had remained normal. Conclusions Operators closely monitored water level using available control room indication while draining the refueling canal. They quickly recognized that the RCS level was decreasing rapidly and took appropriate actions to stop draining and refill RCS with a high-pressure safety injection pump. However, the operators' decision to fully open Valve 2S1-18 to drain the refueling canal increased the time required to stop draining the reactor vessel and contributed to the inadvertent entry into reduced inventory. The control room supervisor was unaware that the valve required 55 turns to close the valve from the full open position, and the shift superintendent was unaware that the valve was fully opene .

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l 05 Operator Training and Qualification 05.1 Unit 2 - Operator Trainina on Drainina the Refuelina Canal l Insoection Scope (71707)

l l The inspector reviewed the training provided to operators on draining of the refueling canal.

I Observations and Findinas l During the course of interviews, the inspector found that operators did not know the

! correct instrument level of the reactor vessel flange. Operators believed that the level of l the reactor vessel flange and the desired water level for installation and removal of the reactor vessel head were the same level,90 inches above the top of the hot leg. The inspector noted that Procedure 2102.015," Filling and Draining the Refueling Canal,"

l step 7.2.15, referred to the 90-inch level as both the reactor vessel flange level and the head removal level. The inspector found that operators were knowledgeable of other key levels associated with draining water from the reactor vessel, including the level for l coupling and uncoupling control element assemblies, reduced inventory controls, reactor

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coolant pump seal replacement, midloop conditions, and the minimum required level for operation of a shutdown cooling purnp.

l The crew that performed the refueling canal drain on February 2 was a relatively l experienced crew. However, with the exception of the shift superintendent, none of the operators had previously lowered refueling canal level to the top of the reactor vesse Although the inspector found that operators received extensive training on operations during RCS reduced inventory conditions and at midloop conditions, operators did not receive any specific simulator or classroom training related to draining the refueling canal and lowering water level to the top of the reactor vessel. System Training Manuals 2-51," Refueling Outages and Support Equipment," and 2 51-1," Main Refueling Bridge and Reactor Building Fuel Handling Equipment," provided only a limited description of the activity, stating that, when refueling operations were completed, water from the refueling canal was returned to the refueling water tank using the low-pressure safety injection and shutdown cooling systems. These training manuals also discussed the number of gallons of water per inch of level change between the reactor vessel flange and the top of the refueling canal. The elevation listed for the reactor vessel flange was correctly listed as 377 feet 6 inches, but there was not a value listed for level above the bottom of the hot leg as indicated on the level monitors displayed in the control room. in addition, the simulator did not model changing the water level in the refueling cana The inspector noted that qualification cards for reactor operators and senior reactor operators included requirements to discuss limits and precautions associated with filling and draining the refueling canal and to perform or simulate a drain of the refueling cana .

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-11 - Conclusions Operators were generally unaware of the critical RCS levels associated with draining the refueling canal to the top of the reactor vessel. The training provided to operators on draining the refueling canal was inadequat Miscellaneous Operations issues (71707)

0 Unit 2 - Risk Assessment I Insoection Scope (71707)

Following the event, licensee personnel evaluated the < afety significance of the inadvertent entry into reduced water inventory condit!ons in the RCS on February The inspector and a senior reactor analyst in the NHC Region IV office reviewed the ;

results of the licensee's risk assessmen I Observations and Findings_

Licensee engineers calculated the reduction in the time to boiling and time to core uncovery for various RCS levels. At the 56-inch level, the lowest level experienced during the event, time to boiling was 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> 20 minutes and time to core uncovery was I 11 hours1.273148e-4 days <br />0.00306 hours <br />1.818783e-5 weeks <br />4.1855e-6 months <br /> 39 minutes. If the operators had not responded quickly and level decreased to ;

O inches, the time to boiling was calculated to be 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> and the time to core uncovery !

was 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> 9 minutes. At the time of the event, operators had several water sources, pumps, and flow paths available to provide makeup water to the RCS and remove decay heat. Available equipment and water sources included one charging pump, three high-pressure safety injection pumps, two containment spray pumps, the boric acid makeup tank, and the refueling water tank. Two low-pressure safety injection pumps were also available, although an assessment assumption was the cavitation and loss of one pum The required makeup rate was determined to be 21 gpm because of the low reactor core decay heat. The assessment conclusion was that, with the multiple sources of makeup water, the high level of mitigation equipment redundancy and diversity, and quick operator response, the event was of minimal safety significanc Licensee engineers performed a quantitative probabilistic safety assessment using existing plant conditions at the time of inadvertent entry into reduced inventory conditions and concluded that the event was not risk significant. The basis for this conclusion was the availability of multiple sources of makeup water, multiple makeup flow paths, and sufficient time to recover from a loss of shutdown cooling.

l The inspector and senior reactor analyst reviewed the licensee's risk assessment and determined that it was accurate and based on reasonable inputs and assumption i

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, Conclusions (

Licensee engineers evaluated the risk significance of the inadvertent reactor vessel l drain event and concluded that the event was of minimal safety significance. This l conclusion was based on the multiple sources of makeup water available, the high level j of mitigation equipment redundancy and diversity, and the quick operator identification l of and response to the even .2 Unit 2 - Results of Licensee's Event InvestiaMon Team Inspection Scoce (71707)

i in response to the inadvertent entry into reduced water inventory conditions in the RCS

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on February 2, licensee management formed an event investigation team to review the event, identify root and contributing causes, and recommend corrective actions to prevent recurrence of the event. The inspector received periodic briefings by the team i leader dvring their investigation and reviewed the team's findings and conclusion I Observations and Findinos

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The event investigation team was lead by the Unit 1 plant manager and included I representatives from plant management and the licensing, industry events, and Units 1 l and 2 operations departments. The team also included a root cause analys The team's immediate actions concentrated on the identification of initial lessons learned and any corrective actions needed prior to the next scheduled draining of the RCS to midloop conditions. The team identified and licensee personnel completed the following actions prior to draining the RCS to midloop on February 4:

. Reviewed Procedure 2103.011," Draining the Reactor Coolant System," to ensure it's accurac . Conducted simulator training for the crew scheduled to perform the RCS drain to midloo . Validated the levels listed in Procedure 2103.011, Attachment L, against verified print . Verified that the levels and noun names for the levels contained in

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Procedure 2103.011 were correct.

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. Verified the adequacy of the planned IPTE briefing for the evolutio . Ensured that the crew reviewed all applicable prerequisites listed in Procedure 2103.01 L

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. Evaluated open items resulting from previous reviews of induMry events l

l associated with draining the RCS to determine if any immediate action needed to be taken.

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. Ensured that the crew understood the relationship between the change in RCS volume and the change in indicated leve . Ensured that management expectations regarding local RCS level watch

requirements were understood and satisfied.

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l . Discussed the event investigation team's preliminary lessons learned with the crew prior to draining to midloo The team concluded their investigation and issued their report on February 17. The team identified two root causes and several contributing causes. The root causes included:

. Failure to fully recognize or treat the refueling canal as an extension of the RCS, l resulting in not applying the same degree of procedural improvements and controls and operator training improvements as those applied to other RCS drain procedures. There was a generallack of recognition of the potential hazards associated with the evolutio . Inadequate written communications and change management, including technical inaccuracies introduced into the procedure during the change process, failure to detect the inaccuracies during the procedure review and approval process, omission of relevant information in the procedure, a procedure that was not designed for the less practiced users, and changes to the intent of a step that were incorrectly characterized as cosmetic or administrative change The team identified a number of contributing causes to the event, including

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. Failure to station the refueling canal watch;

. Less than adequate prejob briefing; A

. Use of two low-pressure safety injection pumps to drain the canal from 137 inches to 90 inches with two pumps; and

. Fully opening Valve 2SI 18 to drain the canal to the refueling water tan In addition to the immediate corrective action discussed above, the team identified an extensive list of recommended long-term corrective actions. These recommended corrective actions were presented to plant management and were to be considered in

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conjunction with the review and closeout of Condition Report 2-1999-197.

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-14-The inspector found that the team conducted a thorough review of the event. Their root and contributing causes were consistent with the conclusions of the inspecto c. Conclusions The licensee's event investigation team conducted a thorough, probing review of the inadvertent entry into reduced water inventory conditions, identified valid root and l contributing causes, and proposed a number of corrective actions that address all of the

causes identifie V. Manaaement Meetinas X1 Exit Meeting Summary l The inspector presented the inspection results to members of licensee rnanagement at l the conclusion of the inspection on February 17,1999. The licensee acknowledged the findings presente The inspector asked the licensee whether any materials examined dur'1g the inspection should be considered proprietary. No proprietary information was identifie I

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ATTACHMENT 1 PARTIAL LIST OF PERSONS CONTACTED Licensee C. Anderson, General Manager, Plant Operations G. Ashley, Licensing Supervisor B. Bement, Unit 2 Plant Manager 3. Cotton, Director, Training /EP M. Farmer, Unit 1 Operations D. Fouts, Supervisor, Nuclear Safety Analysis D. James, Manager, Nuclear Safety M. Lloyd, PSA Engineer, Nuclear Safety Analysis L. McLerran, Supervisor, Operator Training S. Pyle, Licensing Specialist M. Ruder, Technical Specialist (Assessments)

T. Russell, Unit 2 Operations Manager J. Smith, Jr., Radiation Protection Manager M. Stroud, Design Engineering Manager C. Zimmerman, Unit 1 Plant Manager NRC C. Marschall, Chief, DRP, Branch C INSPECTION PROCEDURES USED IP 71707: Plant Operations ITEMS OPENED AND CLOSED Opened and Closed 50-368/9903-01 NCV Procedure Error Resulting in inadvertent Entry into Reduced Inventory (Section 03.1)

50-368/9903-02 NCV Refueling Canal Drain Task Not identified as an IPTE (Section 03.2)

50-368/9903-03 NCV Failure to Follow Procedure (Section 04.1)

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LIST OF ACRONYMS USED ,

IPTE infrequently performed test or evolution RCS reactor coolant system I

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ATTACHMENT 2 The following is a detailed chronology of the events leading up to and proceeding the inadvertent entry into reduced inventory conditions. The chronology was derived from station log entries, interviews with personnel involved in the evolution, plant computer data, and l

information obtained from the event investigation team's revie All times represent central standard time on February 2,199 On February 2,1999, Unit 2 was in Day 24 of Refueling Outage 2R13. Refueling was complete, the reactor vessel head was removed, steam generator nozzle dams were ' e'

and the borated water level in the refueling canal was at 397 feet 7 inches elevation (341.8 inches above bottom of hot leg). Unit 2 operators were preparing to lower the waar l levelin the refueling canal to allow installation of the reactor vessel hea TIME ACTION Prior to Control room supervisor conducted prejob briefing with control room ,

2:20 operators and waste control operator on refueling canal drain evolutio '

Decision made to use a dedicated operator to operate Valve 2SI-18 instead of the waste control operato Control room supervisor provided a separate briefing to individuals performing duties outside of the control room, the operator assigned to operate Valve 2SI-18, and the operator assigned to monitor the water levelin the spent fuel poo :20 Commenced draining the refueling canal. Control room supervisor directed the operator to initially open Valve 2S1-18 approximately 15 turns and to fully open the valve following start of the second low-pressure safety injection pum :35 Started second Low-Pressure Safety injection Pump 2P-60A. Refueling canal level 395 feet 8 inches (318 inches).

2:38 Operator fully opened Valve 2SI-18. Drain rate approximately 3.3 inches per minut :32 At 145 inches, control room supervisor directed operators to throttle closed Valve 2SI-18 and stop Low-Pressure Safety injection Pump 2P-60 :37 Stopped draining the RCS at 137 inches for refueling canal water sampl :01 Results of refueling canal water sample receive Control room supervisor had discussion with personnel to refocus operator l

attention prior to recommencing refueling canal drain.

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