ML20101A559
| ML20101A559 | |
| Person / Time | |
|---|---|
| Site: | Crane  |
| Issue date: | 04/24/1992 |
| From: | Broughton R GENERAL PUBLIC UTILITIES CORP. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| C311-92-2054, NUDOCS 9204290041 | |
| Download: ML20101A559 (2) | |
Text
s
^l GPU Nuclear Corporation
- '[ NQQIgf Post Office Box 480 Route 441 South Middletown, Pennsylvania 17057 0191 717 944 7621 TELEX 84 2386 Writer's Direct Dial Number:
(717) 948-8005 7pril 24, 1992 C311-92-2054 U. S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, D.C.
20555
Dear Sir:
Subject:
Three Mile Island Nuclear Station, Unit 1 (Till-l)
Operating License No. DPR-50 Docket No. 50-289 Spent Fuel Pool Rerack This letter confirms the substance of a teleconference between GPUN and the NRC staff on March 26, 1992, regarding clarification of the load handling safety margin and future load test procedures for reuse of the rack lift rig post-layup or storage.
The THI-l Fuel Handling Building crane has a rated capacity of 110 tons. The new fuel rack weighs approximately 13 tons. Although not single failure proof this provides a safety factor of 8.46:1.
Hoists are designed with a 5:1 ultimate strength safety factor (110 tons x 5 - 550 tons) which yields an ultimate strength to load safety factor of 42.3:1. Hoisting rope safety factors for the main hoist are based on the following:
bottom block 5,000 lbs.
=
rated load 220,000 lbs.
parts of rope 12 (1 1/8" each)
=
rope published breaking strength 100,000 lbs
=
Resulting safety factor = 100,000/((220,000 + 5,000)/12) = 5.33:1
$m When lifting a fuel rack at 13 tons or 26,000 lbs, the resulting safety factor - 100,000/(26,000 + 5,000)/12) = 38.7:1. The dynamic factors were-28-calculated conservatively at no-load conditions. Under load conditions, cm stopping time would be longer, and dynamic factors correspondingly smaller. - It -
"O was determined that the maximum dynamic load would be approximately-1% of the p,$
actual load. Therefore, the dynamic loading may be ignored.
In an effort to oc prevent lowering-the main hoist block into the spent fuel pool water it is planned to interpose a 40 ton intermediate hoist between the main hoist hook O!
and the fuel rack rigging. This 40 ton hoist will be used to lower the fut.1
- csm racks into the pool. Although not single failure proof, the safety factor for MSn.
the 40 ton hoist is (80,000 + 26,000) - 3.08:1, with an ultimate st.ength to load safety factor of 15.38:1.
\\
00x GPU Nuclear Corporaton is a subsdarf of General Pubhc Utilmes Corporation
\\
4 Document Control Desk
=
C3.1,1-92-2054
- Page 2
'The rack lifting rig is subject to load testing, as well as visual inspection and liquid penetrant examination of primary structural weld locations prior to initial use in the rerack project. Any future use of the lift rig after an extended storage or la.vup period will necessitate that the lift rig be subject to visual inspection, and procedures will be established for additional load testing at that time.
If any additional information is required, please contact Devid J. Distel at (201) 316-7955.
j Sincerely,
.N T. G. Broug ton Vice President and Director, THI-l DJD/amk cc:
Region I Admin.istrator TMI Senior Resident Inspector TMl-1 Senior Project Manager l