ML20127H425

Informs That Reinspection of Bergen-Paterson Hydraulic Shock Absorbers Will Be Conducted During Plant Outage Scheduled to Begin Late Sept or Early Oct 1973,per Bulletin 73-04

ML20127H425
Person / Time
Site:	Monticello
Issue date:	09/05/1973
From:	Wachter L NORTHERN STATES POWER CO.
To:	Grier B NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
References
IEB-73-04, IEB-73-4, NUDOCS 9211180510
Download: ML20127H425 (5)

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NSIP NORTHERN STATES POWER 'C O M P A N Y M I N N E A PO L.l t. M I N N E S OTA S S 4 01

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September 5, 1973 Mr. Boyce H. Grier, Regional' Director Directorate of Regulatory Operations Region III United States Atomic Energy Commission 799 Roosevcit Road Glen Ellyn, Illinois 61073

Dear Mr. Grier:

In accordance with Item 3 of Directorate of Regulatory Operetions ,

Bulletin 73-4, we are hereby informing you that re-inspection of Bergen-Paterson hydraulic shock absorbers at the Monticello Nuclear Generating Plant will be conducted during a plant outage which is ,

p,resently scheduled to begin late September or early October 1973.

. At that time, it is expected that the plant will have been at operating temperature approximately 45 days subsequent to the inspection performed as requested in R0 Bulletin 73-3.

Yours very truly, LJ achter d

Vice President, Power Production & System Operations

• IJW/dm cc: J F O' Leary-_

G Charnoff Minnesota Pollution Control Agency Attention: Ken Dzugan

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9211180510 730905 PDR ADOCK 05000263' G ppR-

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NORTHERN 5TATES P O VV E R C O M P A N Y ,

MIN N E A PO Li s, MIN N E S OTA 5 5 401 1

j August 9, 1973 I

j Mr Boyce H Grier, Director j Directorate of Regulatory Operations

i. Region III United States Atomic Energy Commission

! 799 Roosevelt Road i Glen Ellyn, Illinois 61037 f

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Dear Mr Grier:

i MONTICELLO NUCLEAR, GENERATING PLANT l ,

i Docket No. 50-263 License No. DPR ?

Defective Hydraulic Shock Suppressors and Restraints-i Identification and inspection of hydraulic shock suppressors at the_Monticello .

Nuclear Generating Plant was completed on July 31, 1973. Inspection results, j corrective measures, and other information requested in Directorate of Regulatory i Operations Bulletin 73-3 are contained in this report.- Plant shutdown for this I inspection was commenced approximately 12 noon July. 30, 1973 in accordance j with that bulletin instruction and further telephone authorization from Mr Boyce l Crier.

[ Fifty nine Bergen-Paterson hydraulic shock suppressors are employed on the various j safety systems at the site. Thirty four are located within thel drywell and the '

, remaining twenty five are located'outside primary containment. An inspection of-all the hydraulic shock.suppressors was completed on July 31, 1973.. The accumul-ator oil level, uns indicated by the tail rod position, and the main piston shaf t extension was noted on each hydraulic shock suppressor.. Low oil l level was identified

! on a total of thirty seven hydraulic shock suppressors; twenty nine of which. are .

' located inside the drywell. All.of the twenty'nine located.in the drywell indicat-l ing low oil 1cvel wereLdisassembled. Three of'the eight located outside. the drywell i indicating low oil level were disassembled. The total of thirty- two hydraulic shock

suppressors disassembled are identified in Table I - Defective Shock Suppressors.

4 General seal deterioration was-noted in all the defective hydraulic. shock suppressors.

[ The main cylinder _ and accumulator cylinder tube 'scals were deformed, gummy and suscept-ibic to thinning with resultant breakage when slightly stretched.1 In general,-the metal parts of the' units appeared:to be in good condition except in a few instances.

These exceptions, as noted in Table I, included two broken accumulator 1 springs, . two-corroded main piston shafts, and one corroded accunulator. piston. The corrosion in all instances-was localized-and appeared as. pitting. The thirty two disassembled units were cleaned and reassembled using new "0"l rings and seals which were provided l

l by -the vendor. The units were refilled using hydraulic fluid, type GE SF1154, as i recommended by the suppressor vendor. The units were tested and reinstalled prior to -returning to power operation..

L MG 131973

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NORTHERN OTATES POWER COMPANY August 9, 1973 Mr B H Grier Oil was added to bring the accumulator tail rod position mid-scale on those units not disassembled. These units were inspected daily for a period of 3 days with no evidence of leakage or failure. All units located outside the drywell will be inspected initially on a weekly basis. The inspection interval will be adjusted appropriately based on future experience. Those units located in the drywell will be inspected at the time of the next rod sequence interchange, presently scheduled for October, 1973. Further actions will depend upon the results of surveillance and the findings of the continuing investigation of the causes of the various defects.

Yours very truly, h h< S Why L J Wachter Vice President -

Power Production & System Operation ,

IJW/ma cc: Mr J F O' Leary, Directorate of Licensing G Charnoff Minnesota Pollution Control Agency

., At tn : Ken Dzugan File Copies sent hv telecopier to Crier and O' Leary

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TABLE I - DEFECTIVE SHOCK SDTPRESSORS

'DENTIFICATION MODEL LOCATION FAILURE MODE SS-1 HSSA-10 Drywell-Main Steam 953 Elev. Seal Deterioration SS-2 HSSA-10 Drywell-Main Steam 953 Elev. ~ Seal Deterioration ,

SS-3 HSSA-10 Drywell-Main Steam 950 Elev. Seal Deterioration SS-4 HSSA-10 Drywell-Main Steam 950 Elev. Seal Deterioration SS-7 HSSA-10 Dyrvell-Main Steam 953 Elev. Seal Deterioration and Localized Corrosion of Piston Shaft.

SS-8 HSSA-10 Drywell-Main Steam 953 Elev. Seal Deterioration and Localized Corrosion o Piston Shaft.

Drywell-Feedwater 952 Elev.

SS-11 HSSA-10 Seal Deterioration SS-13 HSSA-10 Drywell-Feedwater 952 Elev. , Seal Deterioration SS-14 HSSA-10 Drywell-Feedwater 952 Elev. ,

Seal Deterioration HSSA-10 Drywell-RHR 964 Elev. Seal Deterioration

.SS-17A SS-17B HSSA-10 Drywell-RHR 964 Elev. Seal Deterioration SS-18A 'HSSA-10. Drywell-RHR 964 Elev. Seal Deterioration SS-18B HSSA-10 Drywell-RHR 964 Elev. Seal Deterioration SS-19 HSSA-10 Drywell-RHR 964 Elev. Seal Deterioration SS-20 HSSA-10 Dyrwell-RHR 964 Elev. Seal Deterioration SS-1AR HSMR-30 Drywell-Recirc 922 Elev. Seal Deterioration and a Broken Accumulator Spring ,

SS-1BR HSMR-30 Drywell-Recire 922 Elev. M Seal Deterioration SS-2AR HSMR-30 Drywell-Recire 927 Elev. Seal Deterioration

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, l TABLE 1 - DEFECTIVE SHOCK SUPPRESSORS (Cont'd.) l LOCATION FAILURE MODE DENTIFICATION MODEL HSMR-30 Drywell-Recire 927 Elev. Seal Deterioration ,

SS-2BR HSMR-30 Drywell-Recire 927 Elev. Seal Deterioration SS-3AR HSMR-30 Drywell-Recire 927 Elev. Seal Deterioration SS-3BR HSMR-30 Drywell-Recire 934 Elev. Seal Deterioration SS-4AR (2)

Drywell-Recirc 934 Elev. Seal Deterioration SS-4BR (2) HSMR HSMR-30 Drywell-Recirc 941 Elev. Seal Deterioration SS-SAR Drywell-Recire 941 Elev. Seal Deterioration SS-5BR HSMR-30 Drywell-Recire 953 Elev. Seal Deterioration, Corroded Accumulator Piston SS-6AR HSMR-20 add Broken Spring.

HSMR-20 Drywell-Recire 927 Elev. Scal. Deterioration SS-6BR ,

HSSA-10 RHR Room-Core Spray 899 Elev. Seal Deterioration 3S-26 HSSA-10 HPCI Room-HPCI 912 Elev. Seal Deterioration SS-35 t HPCI Room-HPCI 896 Elev. Seal Deterioration SS-36B HSSA-10 -

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