ML20125B198
| ML20125B198 | |
| Person / Time | |
|---|---|
| Site: | Monticello  |
| Issue date: | 08/09/1973 |
| From: | Wachter L NORTHERN STATES POWER CO. |
| To: | Grier B NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| References | |
| NUDOCS 9212090253 | |
| Download: ML20125B198 (4) | |
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NSBs NORTHERN STATES POWER. COMPANY e
MIN N E A Pol l s, MIN N E S OTA 5 5 401 August 9, 1973 Mr Boyce H Grier, Director Directorate of Regulatory Operations Region III United States Atomic Energy Commission 799 Roosevelt Road Glen Ellyn, Illinois 61037
Dear Mr Grier:
MONTICELLO NUCLEAR, GENERATING PLANT Docket No. 50-2,63 License No. DPR-22 Defective Hydraulic Shock Suppressors and Restraints Identification and inspection of hydraulic shock suppressors at the Monticello Nuclear Generating Plant was completed on July-31, 1973.
Inspection results, corrective measures, and other information requested in Directorate of Regulatory Operations Bulletin 73-3 are contained in this report. Plant shutdown for this inspection was commenced approximately 12 noon July 30, 1973 in accordance with that bulletin instruction and further telephone authorization from Mr Boyce Grier.
Fifty nine Bergen-Paterson hydraulic shock suppressors are employed on the various safety systems at the site. Thirty four are located within the 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, as indicated by the tail rod position, and-the main piston shaf t extension was noted on each hydraulic shock suppressor. Low oil 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-ing low oil icyc1 were disassembled.
Three of.the eight located outside the drywell indicating low oil level were disassembled. The total of thirty two hydraulic shock suppressors disassembled are identified in Table I - Defective Shock Suppressors.
General seal deterioration was noted in all the defective hydraulic shock-suppressors.
The main cylinder and accumulator cylinder tube seals were deformed,' gummy and suscept-ible to thinning with resultant breakage when slightly stretched.
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 springs, two-corroded main piston shafts, and one corroded' accumulator piston. The corrosion in all instances was localized and appeared as pitting. The thirty two disassembledL units _ were cicaned and reassembled using new "0" rings-and seals which were provided by the vendor. The units were refilled using hydraulic fluid, type GE SF1154, as recommended by the suppressor vendor. The units were tested and reinstalled prior to returning to power operation.
9212090253 730809 AUG13Jgg PDR ADOCK 05000263 G
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NORTHERN OTATES POWER ' COMPANY Mr B H Grier August 9,1973 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 Icakage 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
Yy l
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
, Attn: Ken Dzugan File Copies sent by telecopier to Crier and O' Leary J
TABLE I - DEFECTIVE SHOCK SUP?RESSORS DENTIFICATION MODEL LOCATION sFAILURE 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 HSSA-10 Drywell-Main Steam 950 Elev.
Seal Deterioration SS-7 HSSA-10 Dyrwell-Main Steam 953 Elev.
Seal Deterioration and Localized Corrosion of Piston Shaft.
SS-8 HSSA-10 Drywell-Main Steam 953 Elev.
Seal Deterioration and Incalized Corrosion o
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Piston Shaft.
SS-11 HSSA-10 Drywell-Feedwater 952 Elev.
Seal Deterioration SS-13 HSSA-10 Drywell-Feedwater 952 Elev.
Seal Deterioration SS-14 HSSA-10' Drywell-Feedwater 952 Elev.
Seal Deterioration SS-17A HSSA Drywell-RHR 964 Elev.
Seal Deterioration 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 Dyrvell-RHR 964 Elev.
Seal Deterioration SS-1AR HSMR-30 Drywell-Recire 922 Elev.
Seal Deterioration and a Broken Accumulator Spring SS-1BF.
HSMR-30 Drywell-Recire 922 Elev.
Seal Deterioration SS-2AR HSMR-30 Drywell-Recire 927 Elev..
Seal Deterioration
Page 2 of 4 TABLE 1 - DEFECTIVE SHOCK SUPPRESSORS (Cont'd.)
DENTIFICATION
-MODEL LOCATION FAILURE MODE
[
'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 927 Elev.
Seal Deterioration e
SS-4AR (2)
HSMR-30 Drywell-Recire 934 Ele i.
Seal Deterioration SS-4BR (2)
HSMR-30 Drywell-Recire 934 Elev.
Seal Deterioration f
'SS-5AR.
HSMR-30' Drywell-Rectre 941 Elev.
Seal. Deterioration Seal Deterioration SS-5BR HSMR-30 Drywell-Recire 941 Elev.
Seal Deterioration, Corroded Accumulator Piston SS-6AR HSMR-20 Drywell-Recire 953 Elev.
and Broken Spring.
SS-6BR HSMR-20 Drywell-Recire 927 Elev.
Seal. Deterioration
'SS HSSA-10 RHR Room-Core Spray 899 Elev.
Seal Deterioration SS-35 HSSA-10 HPCI Room-HPCI 912 Elev.
Seal Deterioration SS-36B HSSA-10
'HPCI Room-HPCI 896 Elev.
Seal Deterioration I
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NORTHERN STATES POWER
'C O M P A N Y -
e M I N N E A PO L.t s. M I N N E S OTA 5 8401 September 5, 1973 Mr. Boyce H. Grier, Regional Director Directorate of Regulatory Operations Region III United States Atomic Energy Commission 799 Roosevelt Road Glen Ellyn, Illinois 61073 De'ar Mr. Grier:
In accordance with Item 3 of Directorate-of Regulatory Operations 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 presently 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 RO Bulletin 73-3.
Yours very truly, fd-c &
LJ achter Vice President,
-Power Production & System Operations IJW/dm cc: J F O' Leary-G Charnoff Minnesota Pollution Control Agency Attention: Ken Dzugan g g. g h D b "~'
.SEP 1' 01973
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