05000336/LER-1997-017-02, :on 970417,discovered Bypassed Refueling Machine Overload cut-off.Caused by Failure to Incorporate Refueling Machine Design Consideration.Evaluation Will Be Performed to Determine If Mod Needed or TS Change Needed

:on 970417,discovered Bypassed Refueling Machine Overload cut-off.Caused by Failure to Incorporate Refueling Machine Design Consideration.Evaluation Will Be Performed to Determine If Mod Needed or TS Change Needed

ML20148C563
Person / Time
Site:	Millstone
Issue date:	05/16/1997
From:	Joshi R NORTHEAST NUCLEAR ENERGY CO.
To:
Shared Package
ML20148C560	List: 05000336/LER-1997-017, Forwards LER 97-017-00 Which Documents Event That Occurred at Mnps,Unit 2 on 970417.Commitment Made within Ltr,Listed 05000336/LER-1997-017-02, :on 970417,discovered Bypassed Refueling Machine Overload cut-off.Caused by Failure to Incorporate Refueling Machine Design Consideration.Evaluation Will Be Performed to Determine If Mod Needed or TS Change Needed
References
LER-97-017-02, LER-97-17-2, NUDOCS 9705230015
Download: ML20148C563 (3)

LER-1997-017, on 970417,discovered Bypassed Refueling Machine Overload cut-off.Caused by Failure to Incorporate Refueling Machine Design Consideration.Evaluation Will Be Performed to Determine If Mod Needed or TS Change Needed

Event date:
Report date:
Reporting criterion:	10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications
3361997017R02 - NRC Website

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• WRC FORM 366 U.S. NUCLEAR REGULATORY CoMMISslON APPROVED BY C4.8 NO. 3150-0104 to 958 Expires 04r30:ss 2

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FOCIUTY NAuf til DOCKET NUMBER (21 PAGE43)

Millstora Nuclear Power Station Unit 2 05000336 1OF3 TITLE 64)

Bypassed Refuel.ng Machine Overload Cut-off EVENT DATE (5)

LER NUMBER (6)

REPORT DATE (7)

OTHER FACILITIES INv0LvED (8)

SEO AL R

N MONTH DAY YEAR YEAR MONTH DAY YEAR E

NU R

04 17 97 97 -- 017 --

00 05 16 97 OPERATING THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF lo CFR 5: (Check one or more) (11)

MODE (9)

N 20.2201(b) 20.2203(aH2)(v)

X 50.73(aH2Hi) 50.73(a)(2Hviii)

POWER 20.2203(a)(1) 20.22o3(aH3)(i)

So.73(aH2)(ii) 50.73(aH2Hz)

LEVEL (10) 000 20.2203(a)(2Hi) 20.2203(aH3Hii) 50.73(aH 2Hiii) 73.71 20.2203(a)(2)(ii) 20.2203(a)(4) 50.73(aH2Hiv)

OTHER 2o.2203(a)(2Hiii) 50.36(c)(1)

So.73(aH2)(v)

Specify in Abstract below

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.....,iiv) 50.3E':H2)

So.73(a)(2)(vii)

IPf NRC Form 366A IJCENSEE CONTACT FoR THIS LER (12)

NOME TELEPHONE NUMBER lanclude Area Codel R. G. Joshi, MP2 Nuclear Licensing (860) 440 2080 COMPLETE ONE LINE FOR EACH COMPONENT FAILURE DESCRIBED IN THIS REPORT (13) k

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CAUSE

SYSTEM COMPCNENT MANUFACTURER

CAUSE

SYSTEM COMPONENT MANUFACTURER g

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wm MONN DAY M AR SUPPLEMENTAL REPORT EXPEr:TED (14)

EXPECTED YES SUB'AISSION r

X NO DATE(ISI (if yes, complete EXPECTED SUBMISSION DATE).

ABSTRACT (Limit to 1400 spaces, i.e., approximately 15 single-spaced typewritten lines) (16)

On April 17,1997, an evaluation was completed which concluded that overload protection is not provided for approximately nine inches of vertical travel on the refueling machine hoist as it transitions from the " fuel only" region to the " fuel plus hoist box" region. Technical Specification LCO 3.9.6 requires overload protection when the crane is operable.

The cause of this event was a failure to incorporate refueling machine design considerations (overload cut-off bypass function) during development of the original Technical Specification criteria.

An evaluation will be performed to determiw if a design modification should be performed for the Refueling Machine hoist overload protection circuit or if a Technical Specification change should be initiated.

9705230015 970516 PDR ADOCK 05000336 S

PDR NRCFORM 366 (4-95)

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tRC FORM 366A U.S. NUCLEAR REGULATORY COMMisslON (4 95)

LICENSEE EVENT REPORT (LER)

TEXT CONTINUATION FACILITY NAME (1)

DOCKET LER NUMBER i6)

PAGE (3)

SEQUENTIAL REVislON YEAR NUMBER NUMBER 2OF3 Millstone Nucicc Power Station Unit 2 05000336 97 - 017 -

00 TEXT til more space as required, use additional copies of NRC Form 366A) 07) 1.

Description of Event

On April 17,1997, an evaluation was completed which concluded that overload protection is not provided for approximately nine inches of vertical travel on the refueling machine hoist [HOl] as i. transitions from the " fuel only" region to the

• fuel plus hoist box" region. Technical Specification LCO 3.9.6 requires overload protection when the crane [FHM]is operable. At the time of discovery of this event, the unit was defueled.

The Refueling Machine is a traveling bridge which spans the refueling pcol. Mounted on the bridge is a trolley that carries the control console and refueling mast assembly. Within the mast assembly is the fuel handling hoist box assembly which is moved in a vertical direction by the hoist cable [CBL] attached to the hoist drive unit. The hoist box assembly, an open-end box, contains a grappling @vice for engagement with the fuel assembly.

During operation the hoist box assembly is lowered from the mast over the core region. At the end of its travel, the hoist box is suspended on downstops which are attached to the mast. At this point the weight of the hoist box is no longer suspended from the hoist cable. The grappling device is lowered and engaged to the top of the fuel assembly. Then the fuel assembly is raised out of the core region and into the hoist box assembly. The load on the cable, at this point, is that of the grapple and fuel assembly only. During all vertical movement, the load On the hoist is monitored to ensure that movement is not restricted.

As the fuel assembly is being raised, loads in excess of the overload cut-off will automatically stop vertical movement of the hoist. When the fuel assembly is fully within the host box the hoist cable will begin to pick up the weight of the hoist box. As the hoist box assembly starts to lift, the overload protection cut-off is bypassed to prevent the additional loads from inertial and frictional forces from exceeding the overload setpoint and shutting off the hoist motor. The fuel assembly and hoist assembly are then raised into the refueling machine mast, so that the fuel assembly can be transported. The refueling machine was originally designed so that the overload cut-off limit is bypassed within this transition area. The bypass is part of the original system design, which pre-dates the implementation of the unit's Technical Specifications.

Technical Specification LCO 3.9.6.d requires "An overioad cut-off limit of </= 3000 pounds in the ' fuel plus hoist box' region." This LCO is applicable during all movements of fuel assemblies. The overload cut-off ensures that the core intemals and pressure vessel are protected from excessive lifting force in the event they are engaged 8

during lifting operations. The ACTION statement states that with the above requirements not satisfied, suspend all crane operations involving moverr.ent of fuel assemblies. Contrary to this requirement, the overload protection function is bypassed wher transitioning from the " fuel only" region to the " fuel plus hoist box" region (down stop area) after withdrawal of a fuel assembly from the core region.

This event is bcing reported in accordance with 10 CFR 50.73(a)(2)(i)(B), any operation or condition prohibited by the plant's Technical Specifications.

fl. Cause of Event The cause of this event was a failure to incorporate refueling machine design considerations (overload cut-off bypass function) during development of the original Technical Specification criteria.

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lll. &Lalysis of Event The ovsrload cut-off ensures that the core intemals and pressure vessel are protected from excessive lifting force in the event they are engaged during lifting operations.

MC FORM 366A (4 95)

h "NRC FORM 366A U.S. NUCLEAR REGULATORY CoMMisslON (4-9 51 LICENSEE EVENT REPORT (LER)

TEXT CONTINUATION FACILITY NAME (1)

DOCKET LER NUMBER 6)

PAGE (3)

SEQUENTIAL Revision YEAR NUMBER NUMBER 3OF3 Millstone Nuclear Power Station Unit 2 05000336 97 - 017 -

00 TEXT til more space is reqwred, use aduational copies of NRC Form 366A) (17)

Throughout full travel of the fuel assembly lift, the load indication is continuously monitored by the operators to ensure there is no interference that would result in damage to other core components or pressure vessel internals. Hoist movement is stopped in the transition region to raise the spreader device and to align the refueling machine television camera. The fuel assembly is protected within the hoist box and is clear of the core region during hoist travel throughout the hoist load cut-off bypass region. Common practice is to report any observed load anomalies to the control room during withdrawal or insertion of fuel assemblies in the core and upender.

Therefore, this event was not safety significant.

IV. Corrective Action

An evaluation will be performed prior to entry into Mode 6 from the current outage to determine if a design modification should be performed for the Refueling Machine hoist overload protection circuit or if a Technical -

Specification change should be initiated.

V.

Additional Information

Similar Events No previous similar events involving the refueling machine were identified.

Energy Industry identification System (Ells) codes are identified in the text as [XX].1