05000249/LER-1975-001, For Dresden, Unit 3, Hydraulic Piping Restraint Failure

For Dresden, Unit 3, Hydraulic Piping Restraint Failure

ML17252A815
Person / Time
Site:	Dresden
Issue date:	01/16/1975
From:	Stephenson B Commonwealth Edison Co
To:	James Keppler NRC/RGN-III
References
BBS Ltr. #32-75 LER 75-001-00
Download: ML17252A815 (3)

LER-1975-001, For Dresden, Unit 3, Hydraulic Piping Restraint Failure

Event date:
Report date:
2491975001R00 - NRC Website

text

Co~monwealrAdison A

One Fifst National *.

Chicago, Illinois W

Address Reply to: Post Office Box 767

'Chicago, Illinois 60690 BBS Ltr. #32-75 Dresden Nuclear R. R. #1 Morris, Illinois January 16, 19

~

Mr. James G. Keppler, Regional Director Directorate of Regulatory Operations-Region III U. s. Atomic Energy Commission 799 Roosevelt Road Glen Ellyn, Illinois 60137 S~T: REPORT OF ABNORMAL OCCURRENCE PER SECTION 6.6.A OF THE TECHNICAL SPECIFICATIONS HYDRAULIC PIPING RESTRAINT FAILURE

References:

1) Regulatory Guide 1.16 Rev. 1 Appendix A

2) Notification of Region III of AEC Regulatory Operations Telephone: Mr. P. Johnson, 1445 hours0.0167 days <br />0.401 hours <br />0.00239 weeks <br />5.498225e-4 months <br /> on January 6, 1975 Telegram:

f'1r. James G. Keppler, 1545 hours0.0179 days <br />0.429 hours <br />0.00255 weeks <br />5.878725e-4 months <br />.on January 6, 1975

3) Report 50-237/1974-53, Inspection of Bergen~Paterson Shock Suppressors Report Number:

50-249/1975-1 Report Date:

January 16, 1975 Occurrence Date:

January 4, 1975 Facility: Dresden Nuclear Power Station, Morris, Illinois IDENTIFICATION OF OCCURRENCE When Unit 3 was shutdown on January 3, 1975, an inspection was made of all thirty-five snubbers in the drywell.

The inspection of the Bergen Paterson shock suppressors on January 4, 1975, revealed that eight snubbers were low on oil with two of them considered inoperable. This condition could have prevented.the performance of the intended safety function of an engineered safety feature system.

CONDITIONS PRIOR TO OCCURRENCE Unit 3 was in the shutdown mode at the time of the inspection.

The last inspection of the drywell snubbers was made about 105 days prior to this inspection.

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Mr. James G. Keppler

,r*' ruary 16,

• 1975 The inoperable snubbers were found duriilg a routine inspection during unit shutdown.

The results of the inspections on the eight low snubbers are given in the following table.

SnubbersFound With Low Levels Snubber Piston Rod Fluid Level Snubber I.D. No.

Extension Position Location 1

2.511 3.511 (low)

B Recirculation Pump 14 2.5" 3.511 (low)

A Recirc Pump Discharge 19 3.011 4.0 11 (low)

Recirc. Header 22 3.011 6.0" (inoperable)

HPCI Line 25 3.5" 6.011 (inoperable)

Feedwater Line 26

1. 011 2.011 (low)

Feedwater Line Line 34 2.511 3.511 (iow) 3A Target Rock Safety Valve 35 2.7511 4.2511 (low) 3A Target Rock Safety Valve Note:

The seal material for the above eight snubbers is ethylene propylene.

DESIGNATION OF APPARENT CAUSE OF OCCURRENCE (Equipment Failure)

The two inoperable snubbers were removed from the drywell and disassembled for a more thorough examination. This inspection revealed that the 0-ring's were pinched, the seals showed slight deterioration and the cylinder was scratched.

No singular cause can be assigned as mode of failure, rather all of the aforementioned problems contributed to the loss of oil from the snubbe~~

ANALYSIS OF OCCURRENCE The two inoperable snubbers did not threaten the health and safety of the public.

The emergency core cooling systems and primary containment were available to provide adequate core cooling and containment within the drywell had a pipe rupture occurred.

CORRECTIVE ACTION

The two inoperable snubbers were replaced with rebuilt snubbers containing ethylene propylene seal material and oil was added to the other six snubbers

Mr. James.*:ith~nerl. da;.

An inspection was made of the eight snubbers to verify proper operation prior to start up.

FAILURE DATA Most of snubber failures in the past were related.to the usage of polyurethane seal material. This occurrence has no singular cause, but is attributable to the several minor problems which allowed an excessive oil leak.age condition to exist during the 105 day operating period between inspections.

On January 16, 1975, Mr. R. Knop of.AF.c Region III was notified that this Abnormal Occurrence report would be submitted 12 days after the date of occurrence due to extended review of the problem.

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J~. B. Stephenson V. Superintendent