IR 05000312/1977003
| ML19317F990 | |
| Person / Time | |
|---|---|
| Site: | Rancho Seco |
| Issue date: | 03/08/1977 |
| From: | Crews J, Malmros M, Morrill P NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION V) |
| To: | |
| Shared Package | |
| ML19317F983 | List: |
| References | |
| 50-312-77-03, 50-312-77-3, NUDOCS 8002210692 | |
| Download: ML19317F990 (4) | |
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S." NUCLEAR REGUIATORY ColetISSION
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OFFICE OF INSPECTION /ND ENFORCEMENT
REGION V
IE Inspection Report No.
50-312/77-03 Licensee Sacramento Municipal Utility District Docket No.
50-312 P. O. Box 15830 License No.
OPR-54 Sacramento, California 95813 Priority Facility Rancho Seco Category C
Location Clay Station. California
Type of Facility PWR, B&W, 913 MWe (2772 MWt)
Type of Inspection Special - t.ER Response Dates of Inspectien '
February 25, 1977 Dates of Previous Inspection January 11-13,1977 (Reactor Inspection)
Principal Inspector N/
-;W 3 P 7 '7 M. H. Malmros; Reactor Inspector Date
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Accompanying Inspectors Y// M '722 M n @
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A rr;11 Reactor Inspector Date S 7~)
G. g/Johnston, Reactor Inspector (Intern)
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Other Accompany
- P sonnel
Reviewed by
/4 80-4/'7 )
Lhews, Chief,ReactorOperationsand
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Nuclear Support Branch N
IE:V Form 219 a
8002210 [%
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SUMMARY
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. Enforcement Action None.
Status of Previously dentified Enforcement Action Not applicable.
Nonroutine Events Not applicable.
Design Changes
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Not applicable.
Other Significant Findings Current Findings On February 24, 1977, the licensee reported to the Region V office that O
the 30,000 gallon reactor coolant system drain tank was damaged by inward buckling and that a one inch nitrogen purge line to the tank was cracked.. A Region V Radiation Specialist at the site verified that the radiological consequr.nces were negligible. On February 25, 1977 Region V reactor inspectors examined the circumstances leading to, the immediate action taken, and potential repairs / modifications associated with the reactor coolant system drain tink failure. The licensee's actions to date appear satisfactory.
S tatus of Previously Identified Unresolved Items and Other Items of Interest Not applicable.
i Management Interview The results of the inspection were discussed with Mr. Oubre and l
other members of SMUD management. The licensee will submit a 30 day'
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Licensee Event Report to the NRC Region V office.
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DETAILS
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Persons Contactui-P. Oubre,-Assistant Plant Superintenden::, Operations-J. McCulligan, Assistant Plant Superintendent, Technical Support R. Colombo, Technical Assistant D. Cass, Maintenance Supervisor
F. Eisenhudt, Assistant Nuclear Engineer J. Field, Assistant Mechanical Engineer R. Smith, Mechanical Engineer.
2.
Reactor Coolant Drain Tank Deformation The circumstances'and proposed corrective action including observation of interim corrective measures related to the deformation of the reactor coolant drain tank (RCDT) were dis-cussed with licensee represeritatives. The inspectors attended a meeting of the Plant Review Comittee during which interin operat.ional considerations were discussed, and proposed repair methods were presented by facility mechanical engineers and the Maintenance Supervisor. Each of the methods for repairing and returning the RCDT to normal service which were proposed requires j
V additional evaluation before a final comitment for repairs can be made by the licensee. The corrective action to be taken by
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the licensee to repair the RCDT and' preclude recurrence of the tank deformation will be the subject of a Licensee Event Report which will be submitted by the licensee nRhin 30 days. Based i
on additional discussions with licensee representatives and observations by the inspector, the following findings pertinent-to the deformation of the RCDT as appropriate to the facility status were made.
a.
The tank deformation was identified when the RCDT compartment was found to be a source of higher than i
normal ~ gaseous activity readings in the Auxiliary i
Building. The higher than nomal gaseous activity
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was attributed to the RCDT venting to the RCDT compartment through a crack in the weld which joins the nitrogen supply line to the top of the tank.
The weld failure was attributed to the buckling of the tank at five locations with defomations inward of as much as one foot with circumferences of 12 to 15 feet.
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The RCDT has been drained and removed from service.
The reactor coolant system drains have been routed to the reactor building accumulator tank Containment isolation criteria are met under this revised routing of reactor coolant system drains.
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c.'
Continued ~ operation without the RCDT does not have an effect on facility systems required to function during analyzed accidents.
d.
There was no measurable release of radioactivity off-site as a result of this occurrence.
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The apparent cause of the tank defomation was the lack e.
of tank venting during transfer of water from the tank.
The tank design for control of internal pressure was being reviewed by the licensee for possible modification as part of the repair plans.
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