View source for 05000298/LER-1985-011, Identifies Defect in Certain DC Motor Starters Used for Controlling ECCS & Primary Containment Isolation Valves, Initially Reported in 851119 LER 85-011.Certain Starters Missing Spacers,Causing Cracking of Disconnect Switch

{{Adams
| number = ML20136E274
| issue date = 12/26/1985
| title = Identifies Defect in Certain DC Motor Starters Used for Controlling ECCS & Primary Containment Isolation Valves, Initially Reported in 851119 LER 85-011.Certain Starters Missing Spacers,Causing Cracking of Disconnect Switch
| author name = Pilant J
| author affiliation = NEBRASKA PUBLIC POWER DISTRICT
| addressee name = Martin R
| addressee affiliation = NRC OFFICE OF INSPECTION &amp; ENFORCEMENT (IE REGION IV)
| docket = 05000298
| license number = 
| contact person = 
| document report number = NUDOCS 8601060484
| document type = CORRESPONDENCE-LETTERS, INCOMING CORRESPONDENCE, UTILITY TO NRC
| page count = 2
}}
{{LER
| Title = Identifies Defect in Certain DC Motor Starters Used for Controlling ECCS & Primary Containment Isolation Valves, Initially Reported in 851119 LER 85-011.Certain Starters Missing Spacers,Causing Cracking of Disconnect Switch
| Plant = 
| Reporting criterion = 
| Power level = 
| Mode = 
| Docket = 05000298
| LER year = 2085
| LER number = 11
| LER revision = 
| Event date = 
| Report date = 
| ENS = 
| abstract = 
}}

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      .N Nebraska Public Power District           "
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Ts8500353 December 26, 1985 p-
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uj -                   df Mr. Robert D. Martin Regional Administrator                              j 1-f DEC 3 01985     I dl i
U.S. Nuclear' Regulatory Commission Region IV 611 Ryan Plaza Drive Suite 1000 Arlington, Texas 76011

==Dear Mr. Martin:==

==Subject:==
Cooper Nuclear Station - DC Motor Starters Failure Nuclear Regulatory Commission Docket No. 50-298, DPR-46

==Reference:==
: 1) LER 85-011 "High Pressure Coolant Injection System Inoperability" dated November 19, 1985 This letter is written to advise that Nebraska Public Power District has identified a defect in certain DC motor starters used for controlling ECCS and primary containment isolation valves. The starters were designed by, and supplied to, NPPD by Nutherm International, Inc., Mt. Vernon, Illinois.           The initial observation of this defect was reported in Reference 1.
In the manufacturing of the starters, the 60 amp disconnect switches (General Electric Model Number THC32S) were modified to permit the use of ring-tongue wire terminals. This modification removed the existing compression fitting and installed a spacer
:              in place of the extension with the compression fitting.             These spacers were missing from some of the starters suppliad to Cooper i
Nuclear Station and led to cracking of the phenolic base of the disconnect switch.       This cracking could permit the shorting of the power leads which.could cause loss of power to the s ta r te r and render the valve actuator inoperable.
The problem was discovered during the replacement of blown fuses j              in one starter.      After discovery of the problem, all installed starters manufactured by Nutherm were inspected.              A Nutherm representative was present to assist in the inspection and repair of the remaining starters.
Of the 28 starters supplied by Nutherm, nine had the THC32S disconnect switches.       Three of these starters had the required spacers properly installed, and one had previously been replaced.
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    's      Mr. Robart D. Martin =
      . Dac;mbsr 26, 1985 Pago 2 i
of the remaining five, two switches were cracked and had to be replaced. The remaining three had no indication of cracking and only required that the spacers be. installed.
Due   to   design  differences,  the disconnect  switches   in the remaining starters were not subject to this cracking problem; however,. they were also inspected with no further problems found.
All the installed starters have been inspected and necessary repairs made; therefore, NPPD considers this issue resolved.
If the staff is of the opinion that Reference 1 should be supplemented tc; contain the above additional information, please contact my office.
S ince rely, Jay M. Pilant Manager, Technical Staff Nuclear Power Group ll JMP/ DAW: cts-lg cc:   Director, USNRC Office of Inspection ind Enforcement (3 copies)
Leonard F. Hinson (Nutherm International)
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