ML20236K297

Comments on Review of Draft AO Rept Provided by 860407 Memo. Failure of Lifting Rig Attachment While Lifting Upper Guide Structure at Facility Addressed

ML20236K297
Person / Time
Site:	Saint Lucie, 05000000
Issue date:	04/29/1986
From:	Grace J NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
To:	Heltemes C NRC OFFICE FOR ANALYSIS & EVALUATION OF OPERATIONAL DATA (AEOD)
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References
FOIA-87-377 NUDOCS 8708070072
Download: ML20236K297 (2)

Text

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• $* $ 101 MARIETTA STRFET, N.W. l

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%*****/ April 29, 1986

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MEMGRANDUM FOR: Clemens J. Heltemes, Jr., Director, Office for Analysis and Evaluation of Operational Data FROM: J. Nelson Grace, Regional Administrator

SUBJECT:

ABNORMAL OCCURRENCE REPORT TO CONGRESS FOR FIRST QUARTER i CY 1986 Per your request, Region II has reviewed the draft Abnormal Occurrence (A0)

Report provided by your memorandum of April 7, 1986. The following writeup is provided as requested:

Possible Appendix "C" Item, Failure of Lif ting Rig Attachment While Lifting the Upper Guide Structure (UGS)

On November 6,1985, while lifting the upper guide structure from the St. Lucie Unit I reactor vessel in preparation for refueling, one of three lifting rig attachments gave way. This placed the upper guide structure lifting rig in a position canted upward approximately six inches and the guide structure canted downward approximately six inches at one of the three attachment points. An attempt was made by Florida Power and Light (FP&L) to lower the load back to its-installed position; but the load cells indicated binding. Therefore, the attempt  ;

was terminated after lowering the load a few inches. The forty-five ton load was '

left suspended about eight feet above the irradiated fuel.

1 FP&L declared an unusual event at 10:45 a.m. (EST) in accordance with plant  !

emergency procedures. All core alterations were suspended ar.d containment integrity was enhanced by resuming full use of the airlocks. Temporary, primary manway covers were installed on both hot and cold legs to enhance the nozzle dams.

The UGS is supported in the reactor vessel by its upper flange. It is aligned by eight aligrenent keys, four at the top and four at the bottom. The structure fits down inside the core support barrel, just above the fuel assemblies. The fuel assembly alignment plate is the bottom component of the UGS. The lifting i

rig is attached to the upper guide structure by three vertically orien';ed bolts.

These bolts are attached from above the water line by torque tools that run down the hollow columns of the rig. Combustion Engineering's procedure for attaching i the rig calls for checking for t' read engagement and torquing each bolt to fifty foot-pounds.

The inspector reviewed the licensee's procedure entitled, " General Maintenance Procedure (GMP) Number 1-M-0015, Revision 12,ReactorVesselMaintenance-Sequence of Operation," which omitted the step concerning the check for thread engagement.

CONTACT:

J. Mathis i

FTS: 242-5587 8708070072 070904 PDR FOIA pgg CORDON 87-377 pg

Clemens J. Heltemes, Jr. 2 April 29, 1986 Subsequent inspection of the bolt that had pulled loose indicated that part of the last thread was stripped. The failure assumed was that this bolt cross-threaded or bound d ue to rig-to-guide-structure misalignment during attachment and reached the fifty foot-pound torque requirement with only part of one thread engaged. During the lift, the few inches of unengaged bolt shaft were pulled through the lifting rig until the bolt head rested on the rig's surface at the bottom of the column, resulting in an imperceptible tilt. The resulting lateral load was initially supported by the guide pins. When the rig and guide structure were lifted about eight feet, it is surmised that sufficient lateral motion was permitted to allow the thread of the improperly engaged bolt i

to strip.

l To prevent a recurrence of the UGS failure, the licensee has revised procedure GMP 1-M-0015 to incorporate sign-off steps for full thread engagement of the i lifting bolts prior to lifting the upper guide structure.

l The safety implication of dropping heavy loads into the open reactor vessel is '

that full assemblies might be sufficiently damaged to release the radioactive gases and iodines held within the fuel clad gap. The event did not result in any adverse effects on health and safety of the public or licensee personnel.

Inspections were performed by NRC Regional personnel. One violation was identified during Region II inspection against 10 CFR 50 Appendix B, Criterion V. NRC Inspection and Enforcement Information Notice No. 86-06 was l l

issued on February 3,1986, to notify licensees of a potentially significant problem that occurred during the movement of a heavy load over the reactor core

• i (Reference C-1).

Reference:

C-1 U. S. Nuclear Regulatory Commission, Inspection and Enforcement Information i Notice No. 86-06, " Failure of Lifting Rig Attachment While lifting the Upper l Guide Structure at St. Lucie Unit 1," February 3,1986. '

No other changes are suggested and Region II concurs with the remainder of those items relevant to Region II responsibility.

Should you have any questions concerning this matter, please contact us.

1 . hw J. Nelson Grace <

l cc: P. Bobe, AE00

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