ML20031C615
| ML20031C615 | |
| Person / Time | |
|---|---|
| Site: | Rancho Seco |
| Issue date: | 09/29/1981 |
| From: | Mattimoe J SACRAMENTO MUNICIPAL UTILITY DISTRICT |
| To: | Stolz J Office of Nuclear Reactor Regulation |
| References | |
| TAC-46519, NUDOCS 8110070356 | |
| Download: ML20031C615 (2) | |
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o O.s suun SACRAMENTO MUNICfPAL UTILITY DISTRICT O 6201 S Street. Box 15830, Sacramento, California 95813; (916) 452 3211 Septembcr 29, 1981 64 t\\
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DIRECTOR OT h'JCLEAR REACTOR REGULATION J>
ATTENTION JOHN F STOLZ CHIEF
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I DOCKET 50-312 RANCHO SECO NUCLEAR GENERATING STATION 1
UNIT NO 1 TOWER CRANE USl' Our letter of June 12, 1981, requested your review and approval of the new tower crane installation at Rancho Seco. Your letters of August 11, 1981 and September 14, 1981, requested extensive additional detailed design analysis of the tr>wer crane's capabilities. Since it may take as long to complete the requested analysis as it would take to complete the building that is being ecastructed and dismantle the crane (April, 1982), this approach is irpractical. Therefore, in answer to your stated concerns, we offer the foll.owing engineering evaluation as appropriate for this very limited short term concern.
The Pecco Model PC 1400 tower crane has a rated capacity of 11,500 pounds at the maximum reach of 90 feet. The crane will be used primarily j
for the following:
A.
Lifting prefabricated form panels weighing apprnximately 2,000 pounds.
B.
Lifting rebar bundles weighing approximately 2,500 pounds.
C.
Lifting wet concrete containers weighing no more than 9,000 pounds.
D.
Lifting steel guiders weighing approxime.tely 9.000 pounds.
E.
Lifting walkway bridge truss weighing approximately 4,000 pounds.
F.
Pipes and conduits weighing 2,000 pounds or less.
All of the above loads are considerably lower than the crane capacity with the maximum load being 78% of the minimum rated capacity of 11,500 pounds and i<ill rare.1v. if ever, extend to the full length of the boom. It is estimated that the crar.: will be operating approximately four hours out of the eight hour work da;., and only 25% of the crane operating time will the crane lift any single load more than 2,500 pounds. We have test loaded
}3 the crane and fouud that it is capable of har.dling the rated loads.
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JOHN F STOLZ Page 2 September 29, 1981 We have also contacted the local office of the United States Weather Bureau and obtained the information that the maximum wind speed recorded in the Sacramento area during the past 50 years occurred in December, 1952 and November, 1953, and reached a peak of 70 mph.
Due to the design of the crane and the large counter balance, the crane does " weather vane" in the direction of the wird, and is rated to 100 mph.
It is felt that a wind 407. higher than ever recorded in Sacramento is very improbable to occur during the next eight months, therefore further calculations are not warranted.
We feel that che UBC approach to th: seismic adequacy of the tower crane is also justified due to the short term of its use.
It is also felt that in any substantial seismic event which may eccur during the next eight months, the following possibilities exist:
- 1) Tower will remain standing as designed.
- 2) Collapse in the direction of the large counter-weight which would not impact the control room, or any Class I piping or tanks.
Again, because of the short term use of the crane, we feel that its use is justified without furthe r calculations.
We do, however, feel that compensatory measures suggested in your letters are necessary, and propose to do the following:
- 1) Train, qualify and have crane operators conduct themselves in acc(rdance with Chapter 4-3 of ANSI B0 30.4-1973, " Portal, Tower and Pillar Cranes".
- 2) Develop load handling instructions.
- 3) Develop operating procedures to define safe load travel paths. This will also include instructions to not operate the crane in winds greater than 30 mph or in temperatures below 300F.
- 4) Provide crane inspection and maintenance in accordance with Chapter 4-2 of ANSI B30-4-1973.
J1 i
ohn. Mattimoe Assistant General P.anager and Chief Engineer d