05000341/LER-1996-018, :on 961105,w/plant in Operational Condition 4 Reactor Head Stud 27 Inadvertently Detensioned During Trim Adjustments.Caused by Transposition Error in Elongation Data Sheet.Stud 27 Retensioned & Procedures Revised

:on 961105,w/plant in Operational Condition 4 Reactor Head Stud 27 Inadvertently Detensioned During Trim Adjustments.Caused by Transposition Error in Elongation Data Sheet.Stud 27 Retensioned & Procedures Revised

ML20135E183
Person / Time
Site:	Fermi
Issue date:	12/05/1996
From:	Jaworsky M DETROIT EDISON CO.
To:
Shared Package
ML20135E156	List: 05000341/LER-1996-018, :on 961105,w/plant in Operational Condition 4 Reactor Head Stud 27 Inadvertently Detensioned During Trim Adjustments.Caused by Transposition Error in Elongation Data Sheet.Stud 27 Retensioned & Procedures Revised
References
LER-96-018, LER-96-18, NUDOCS 9612110059
Download: ML20135E183 (4)

LER-1996-018, on 961105,w/plant in Operational Condition 4 Reactor Head Stud 27 Inadvertently Detensioned During Trim Adjustments.Caused by Transposition Error in Elongation Data Sheet.Stud 27 Retensioned & Procedures Revised

Event date:
Report date:
Reporting criterion:	10 CFR 50.73(a)(2)(1) 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications
3411996018R00 - NRC Website

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LICENSEE EVENT REPORT (LER)

FsosLITY NAME (1)

DocKETMMBfAat PAGE 13i Fermi 2 0 l5 l0 l0 l013 l4 l1 1 l ' l4 Inadvertent Operational Condition Change Due to Detensioned Reactor Vessel Head Bolt EVFNT DAff (O L ER MJMBER (6)

REPORT DATE (7 OTHFR PActLmES INWOLVED (8)

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10 CFR 10CFR50.73(a)(2)(1)(B)

Om OTHER-0l0l0 (Specify in Abstract below and in text, NRC Form 366A)

UCENSEE CONTACT FOR TM5 LER M2)

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On November 5,1996 at 0150 with the plant in Operational Condition 4 (Cold Shutdown) Reactor Vessel Head stud number 27.vas inadvertently detensioned during trim adjustments. This resulted in a reentry into Operational Condition 5 (Refueling) from Operational Condition 4 (Cold Shutdown). Since this was not realized until after the fact, compliance with Technical Specification (TS) 4.0.4, which requires that all surveillances for an Operational Condition are completed prior to entry into that condition, was not met.

The primary cause of th s event was a transposition error on the elongation data sheet for the initial set of dial indicator readings. Since there were no refueling operations in progress at the time, plant safety was not compromised.

l The immediate corrective action taken was to retension stud number 27. Procedural changes will be made to better facilitate the tensioning process. These changes will be completed by May 30,1997 or before the next operation involving entry into Operational Condition 5.

9612110059 961205 PDR ADOCK 05000341 S

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I LICENSEE EVENT REPORT (LER) TEXT CONTINUATION

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0 l5 l0 l0l0 l3l4l1 96 0

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lFl4 0 1 8 Initial Plant Condition:

Operational Condition:

4 (Cold Shutdown)

Reactor Power:

0 Percent Reactor Pressure:

O psig Reactor Temperature:

98 degrees Fahrenheit Description of the Event:

On November 4,1996 with the plant in Operational Condition 5 (Refueling), Detroit Edison personnel commenced tensioning of the Reactor Pressure Vessel (RPV) head [AC][RCT). The tensioning process continued into the next shift. At 1927 the first tensioning pass to 5400 psig was completed and the second pass was initiated. At 2055, per procedure, the Control Room was notified that the last set of studs were ready to be tensioned to 7200 psig and to verify that the plant was ready to enter Operational Condition 4. The Nuclear Shift Supervisor (NSS) gave permission to tension the last four studs and at 2104 declared entry into Operational Condition 4 upon notification that all studs were tensioned to 7200 psig.

At 2156 the NSS was notified that a trim pass was necessary to meet stud elongation tolerance requirements. Due to a transposition error while recording the initial dial indicator reading for stud number 27, the trim adjustment was estimated to require approximately six turns to bring the elongation within tolerance's. The six turns resulted in stud number 27 becoming detensioned at 0150 on November 5,1996. At about 0215 stud number 27 was retensioned to 7200 psig.

Because the RPV was not fully tensioned during the time period from 0150 to 0215, this resulted in a reentry into Operational Condition 5. Compliance with Technical Specification requirements for Operational Condition 5 were not met. Specifically, Technical Specification (TS) 4.0.4, which requires that all surveillances for an operational condition are completed prior to entry into that condition was not met. In this case, the surveillance requirements for TS 3.3.6, " Control Rod Block Instrumentation", for Operational Condition 5 were not completed. There were less than the minimum required operable channels ofIntermediate Range Monitors (IRM) [AC][ MON] per trip function.

Therefore, this event is reportable as a condition prohibited by Technical Specifications in accordance with 10CFR50.73(a)(2)(i)(B).

Cause of the Event; The primary cause of this event was a transposition error of the initial set of dial indicator readings. The transposition error occurred due to poor transfer ofinformation between personnel as it was transmitted by technicians via radio communication from the reactor cavity to the official record on the Refueling Floor. The actual reading of 0.8060 was transposed to be 0.8600 on the official record. This resulted in RPV Head stud number 27 being detensioned during the trim pass and in a reentry into J

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LICENSEE EVENT REPORT (LER) TEXT CONTINUATION gg

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- n Ferm12 0 l5 l0 l0l0 l3l4l1 96 0

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l*l4 0 1 8 TEAT (17)

Operational Condition 5. A contributing factor was that the personnel involved did not adequately review or question the inconsistency in the dial indicator readings or the number of turns required for the trim adjustment.

Analysis of the Event

TS 4.0.4 establishes the requirement that all applicable surveillances must be met before entry into an operational condition. The purpose of this specification is to ensure that system and component operability requirements or parameter limits are met before entry into an operational condition for which these systems and components ensure safe operation of the facility. In this case, the surveillance j

1 requirements for TS 3.3.6, " Control Rod Block Instrumentation", for Operational Condition 5 were not completed. The instrumentation required for this Operational Condition ensures safe operation in the Refueling Operational Condition. There were less than the minimum required operable channels of Intermediate Range Monitors (IRM) per trip function. The IRM's are required to monitor for inadvertent criticality during core alterations. During the 25 minutes that Fermi 2 was inadvertently in Operational Condition 5 no core alterations were in progress. Therefore, the probability ofinadvertent criticality and exposure of personnd to excessive radioactivity was negligible.

Corrective Actions

)

The immediate corrective action taken was to retension stud number 27 to within specified tolerances.

During the investigation it was determined that a declaration of Operational Condition 4 is more 4

appropriate after the trim pass adjustment when all stud elongation is verified to be within tolerances.

Operations will change the declaration of a mode change from Operational Condition 5 to Operational Condition 4 to be when stud elongation is verified to be within tolerance. This will be completed by May 30,1997 or before the next operation involving entry into Operational Condition 5. The procedural changes described below will also incorporate this consideration.

The Reactor Vessel Head Detensioning and Tensioning procedure will be revised to incorpurate :'y following considerations:

Elongation data recorded by technicians in the reactor cavity and reported via radio communications will be compared to the reading recorded on the official records. Any discrepancies will be resolved prior to subsequent elongation adjustments.

Trim adjustments requiring more than one turn will be evaluated by the Refueling Floor Coordinator prior to proceeding with trim adjustments.

LICENSEE EVENT REPORT (LER) TEXT CONTINUATION m,un - o, wce -.

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- m Fermi 2 0 l5 l0 l0l0 l3l4l1 96 0

8 0

4 l5 l 4 TEAT O T)

The definition for a fully tensioned Reactor Vessel Head will be when all studs are verified to be within elongation tolerances.

The NSS will be notified when the studs are ready for trim adjustments to assure the plant is ready to enter Operational Condition 4.

The NSS will also be notified when all studs have been elongated and are verified to be within tolerance.

These procedure revisions will be completed by May 30,1997 or before the next operation involving entry into Operational Condition 5.

A three way comnmnications process involving an acknowledgment that a repeat back was correct will be implemented within appropriate groups as a good practice.

Additional Information

A. Failed Components None B. Previous LER's on Similar Problems LER 87-027 On June 26,1987, the reactor coolant temperature had exceeded 200 degrees Fahrenheit, which placed the reactor into Operational Condition 3 (Hot Shutdown). Control Room operators immediately took corrective action to decrease reactor coolant temperature below 200 degrees Fahrenheit by utilizing Division 1 of RHR in Shutdown Cooling Operational Condition. The surveillance tests required to be performed by Technical Specifications before entry into Operational Condition 3 were not complete.

This event is similar in that it involves personnel error. However, the circumstances which led to this LER are different from the current LER. Therefore, the corrective actions from LER 87-027 could not have precluded the events described in the current LER.