ML19326B417
| ML19326B417 | |
| Person / Time | |
|---|---|
| Site: | Arkansas Nuclear  |
| Issue date: | 10/09/1974 |
| From: | Cavanaugh W, Phillips J, Rueter D ARKANSAS POWER & LIGHT CO. |
| To: | |
| Shared Package | |
| ML19326B413 | List: |
| References | |
| NUDOCS 8004150779 | |
| Download: ML19326B417 (3) | |
Text
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Unusual Event Report No. S0-313/74-3 i
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Report Date:
October 9,1974-3.
Occurrence Date: September 12, 1974 1
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Facility:
Arkansas Nuclear One-Unit 1 Russe 11ville, Arkansas S.
Identification of Occurrence:
Bent spring hanger rods on the pressurizer electromatic relief valve discharge piping.
6.
Conditions Prior to Occurrence:
Steady-State Power Reactor Power 0
Wth Hot Standby Net. Output 0
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Cold Shutdown Dercent of Full Power 0
Refueling Shutdown Routine Startup Operation Routine Shutdown Operation
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Load Changes During Routine Power Operation Other (Specify)
Power Escalation Testing 7.
Description of Occurrence:
During a pipe shock test on the pressurizer electromatic relief valve i
discharge piping, pipe movement readings indicated that the pipe had moved more than the spring hangers would allow. Subsequent investigation found several bent hanger rods resulting from excessive pipe movement during relief valve operation.
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O 8 0 0 415 0 77f July S, 1974 NSP-10, Rev. O Page 1 of 3
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Unusual Event Report No. 50-313/74-3 Sheet 2 8.
Designation of Apparent Cause of Occurrence:
Design X
Procedure Manufacture Unusual Service Condition Including Installation /
Environmental i
Construction Component Failure Operator Other (Specify)
Designed pipe supports were not adequate to restrain the pipe against forces existing when electromatic relief valve was opened.
t 9.
Analysis of Occurrence:
Although.the hanger rods were bent due to pipe movements greater than expected, the integrity of the pipe hangers and pipe restraints was not r-N_/
affected. The pipe movements were not of sufficient magnitude to endanger the integrity of the pipe.
This was verified by a dye
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penetrant examination to check for damage at several locations where i
maximum stress would have occurred. Rupture of the discharge piping would have resulted in the relief valve discharging directly to the Reactor Building atmosphere, but no building design parameters would have been exceeded during the transient.
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- 10. Corrective Action:
At the time of the valve, low when the hanger rods were bent, the dis-b charge pipe was being remotely monitored as part of a test procedure.
Using the information from this test a revised analytical calculation was performed on the discharge piping from the pressurizer electro-matic relief valve and the two (2) pressurizer safety valves. On the basis of this calculation two (2) additional hydraulic snubbers have been added to each of the aforementioned discharge lines.
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July 5, 1974 NSP-l'D, Rev. O Page 2 of 3 e
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Unusual Event Report No. 50-313/74-3 Sheet 3
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- 11. Failure Data:
NA
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Reviews and Approvals:
Reviewed and Approved by: Plant Safety Committee Yes ( ). No (X)
Plant Superintendent Yes ( )
No (X)
Reference:
Not Required Date:
Reviewed by-es a u
Date: /0 V
/ Licensing' Supervisor
. Approved by: N/4/'//,
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Date: /8 -//-7/
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5 afety"Revi Co ttee Approved by:
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nager of Nuclear Servi d
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Approved by-d'/jf p &,/
Date: f)~//- h /
Director of Power Production Approved by:
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Date:
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E Senior Vice~ President t
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July S, 1974 NSP-lb,Rev.O Page 3 of 3
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