ML19319E152
| ML19319E152 | |
| Person / Time | |
|---|---|
| Site: | Rancho Seco |
| Issue date: | 05/12/1975 |
| From: | Mattimoe J SACRAMENTO MUNICIPAL UTILITY DISTRICT |
| To: | |
| References | |
| NUDOCS 8003310671 | |
| Download: ML19319E152 (4) | |
Text
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NRC DIS'818UTION FOR PART 50 DOCKET " TERIAL (TEMPORARY FORM)
CONTROL NO: 5651 1
FILE:
-c FROM: sWD DATE OF DOC DATE REC'D LTR TWX RPT OTHER Sacramento, Calif.
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J.J. Mattinoe-5-12-75 5-28-75 m
TO:
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1-signed SENT t OCAL PDR xx CLASS UNCLASS PROPINFO INPUT NO CYS REC'D DOCKET NO:
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50-312 DESCRIPTION:
ENCLOSURES:
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Ltr ref our phone conservations on 4-29& 4' -
75
..... furn inf o concerning a problem with the reactor building polar crane on 2 75.........
PLANT NAME:Rancho. Seco FOR ACTION /INFORMATION 5-31-75 JGB BUTLER (L)
SCHWENCER (L) ZIEMANN (L)
REG AN (E)
W/ Copies W/ Copies W/ Copies W/ Copies CLARK (L)
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gprRC PDR 4CHROEDER M IMES R. DIGGS (L)
BRAITMAN OGC, ROOM P 506A
,MACCARY GAMMILL H. GEARIN (L)
SALTZMAN SSidK/STAF F KNIGHT KASTNER E. GOUL8DURNE (L)
ME LTZ SE DAWLICKI BALLARD P. KREUTZER (E)
GIAMBL)SSO SHAO SPANGLER J. LEE (L)
_ PLANS BOYD.
9TELLO Mc MAIGRET (L)
MCDONALD MOORE (L)
JOUSTON
_ ENVIRO S. REED (E)
CHAPMAN DEYOUNG (L) gMOVAK MULLER M.
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SKOVHOLT (L)
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- POLITO KNIGHTON M. SLATER (E)
PETERSON P. CO LLINS
.TEDESCO YOUNGBLOOD H. SMITH (L)
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. DENISE J. COLLINS REGAN S. TEETS (L)
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$SMUD SACRAMENTO MUNICIPAL UTILITY DISTRICT O 6201 S Street, Bor 15830 Sacramento, California 95813; (916) 452-3211 liay 12,1975 Nuclear Regulatory Commission k
Region V
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1990 North California Boulevard Walnut Creek, California 94596 Attention: Mr. R. H. Engelken, Director
Dear Mr. Engelken:
Rancho Seco Nuclear Generating Station Unit 1 Docket No. 50-312 As a follow up to the District's telephone discmssions on April 29 and 30, 1975 with Messrs. Johnson and Malmros of your office, we are submitting a report on a problem encountered with the reactor building polar crane.
On approximately February 19, 1974, during a routine safety inspection of the containment building polar crane, some of the bolts which connect the crane and ties to the main girders were found to be loose. This was reported on Nonconforming Report No. 6638.
Prior to dispositioning the Nonconforming Report, the Bechtel Power Corporation verbally reported the problem to the Harn#schfeger Corporation, the crane designer and manufacturer.
It was agreed that the existing ASTM A-325 bolts should be replaced with A-490 bolts to increase the strength of the connection.
Harnischfeger was to investigate the problem and report its findings.
Researching the problem further, Bechtel discovered that the design of the end ties and the bolting connecting them to the main girders did not conform to the original design calculations. The original calculations showed a need for a vertical restraint or " tie-down" to provide acceptable stability during a seismic event. The calculations were amended during the initial review process to add a seismic brace or bumper to prevent the crane from coming off the sup-port steel. However, the calculations received by Bechtel did not reflect the effect of the elimination of the fixed restraint and the design of the end ties furnished.
In spite of both written and verbal comunication with Harnischfeger, we could not get a timely response explaining the discrepancy.
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- 4 Mr. R. H. Engelken May 12, 1975
_Following'the initial replacement of the bolts, their con-dition was carefully monitored and the-problem reoccurred.
It was also discovered that there was an intermittent interference between the run-way supoort steel and the seismic brace.
Existence of the interfercnce was dependent on the relative position of the crane on the rail (1-1/4" lateral movement possible). This interference was eliminated by machining the restraint shoe.
It is not known at this time whether the bolt loosening was due to normal operating stresses or the interference.
Our inability to obtain a satisfactory response from_ Harnischfeger and the need to correct any potential problem prior to fuel loading en-couraged us to have Bechtel perform a detailed analysis of the end ties and their connections to the girders.
This analysis showed a need for greater joint capacity to resist the simultaneous application of vertical and horizontal seismic loads. Revisions 2 and 3 of NCR Ho. 6638 were written to provide for modifications to bring the stresses within allowable limits.
We directed Bechtel to proceed with the work and at the same time. forwarded details of the proposed changes to Harnischfeger for its review and approval.
In its response, Harnischfeger indicated that the work was not required but did not provide any technical support for its position.
We proceeded with the work and completed it prior to fuel loading.
Since that time there have been several meetings and numerous letters between SMUD,-Bechtel, and Harnischfeger, all aimed at reaching agreement on the assumptions used in analyzing end tie stresses during a seismic event. Also, in September and October, 1974, Harnischfeger did review and accept the Bechtel redesign while still maintaining its position that the modification work was not required.
On April 14, 1975, we received the final calculations from Harnischfeger completely reanalyzing the as-shipped crane girder-end tie configuration.
Prior to receipt of these calculations, it had been Harnischfeger's position that the as-st ?pped crane complied with the design requirements. These calculations show that the' crane stability was acceptable; however, the end tie bolting was overstressed.
Although the procurement specifications and FSAR clearly state that the crane is to be designed _for simultaneous application of vertical and horizontal seismic loads, Harnischfeger still feels that the require-ment is unduly severe. There may be some ' validity to this position; ho;;ever, the requirement is 'one to which we committed ourselves and with which we are in compliance.
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Mr. R. H. Engelken
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May 12,1975.
If we can provide any additional information,-please do not-hesitate.to contact us.
Sincerely yours,
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J. J. Mattimoe-Assistant General Manager and Chief Engineer t
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