ML19206A439
| ML19206A439 | |
| Person / Time | |
|---|---|
| Site: | Quad Cities, Crane  |
| Issue date: | 04/01/1976 |
| From: | Kalivianakis N COMMONWEALTH EDISON CO. |
| To: | James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| Shared Package | |
| ML17054D005 | List: |
| References | |
| NJK-76-118, NUDOCS 7904200033 | |
| Download: ML19206A439 (5) | |
Text
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Corcova. lihnois G1242 Tcicpnonc 2C9/G;4 2241 NJK-76-li8 April 1, 1976 J. Keppler, Regional Director Of fice of Inspection and Enforcement Regicn ll!
U. S. Nuclear Regulatory Ccmmission 799 Rcosevelt Read Glen Ellyn, Illinois 60137
Reference:
quad-Cities Nuclear Power Station Docket No. 50-265, CPR-30, Uni t 2 In response to your Inspection Report No. 050-265/76-04, the following report concerning possible generic problems relatec to Electro-Hydraulic Control (EHC) system oil migrating to the cable tunnel area is being submitted.
On October 9,1975, statien persennel were cleaning up EHC fluid which had been dr,ipping on the Unit 2 cable tunnel ficor.
It was noticed not only had the EHC fluid been leaking coto the ficor but also it had been leaking cnto the cables in the surrounding cable pans.
Closer inspection of the cables revealed puffing and plastici:ation of cables that the EHC fluid had made contact with.
At the time of discovery, Unit 2 was in the cold shutdcwn condition.
Cables in the Unit 2 cable tunnel were utili:ed for both safety related and non-sa fety rela ted functions.
The EHC fluid leak had not rendered any safety or non-safety related systems incperable.
The immediate action taken was to determine the extent of plastici:ation of the affected cables. All the cables and cabic pans in the affected area of the Unit 2 cable tunnel were cleaned with a soap and water solutien as reccmmerded by information from the EHC fluid manufacturer.
The cleaning of EHC fluid f rcm the cables should eliminate further ef fects of plas _. _
ticization.
A small section of control cable, which was hand traced to identify its function, was cut out and analy:ed.
I t was di scovered tha t only the overall Jacketing material had been affected by the EHC fluid.
Varices cable manufacturers and the manufacturer of EHC fluid were censul ted as to the ef fects of EHC fluid on varicus polymers used for cable.
Poly-vinylchloride (PVC) and necorene were found to be af fected severely by EHC fluid and not reccmmended for use arcund EHC fluid.
Other polymers such as polyethylene, te fl on, silicone rubber, nylon, and butyl cuacer were acceptable for use around EHC fluid.
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The next course of action was to determine the types of cable In the Unit 2 cable tunnel that were' af fected by the EHC fluid.
The types of cable construction were categorized as follcws:
l.
Control & Power (Icw voltage):
Individual or multiconductor PVC jacketed; mylar wrapped, PVC.over butyl rubber insulated conductors.
2.
Instrumentation:
PVC jacketed, shielded, mylar wrapped,' polyethylene insulated conductors.
3 Instrumentation:
Single and multiconductor PVC jacketed, polyethylene insulated, mylar wrapped and shielded twisted pairs.
4.
Ins trumen ta tion:
PVC Jacketed, polyethylene insulated, ceaxial cable.
The control and pcwer cables comprise'd approximately 80% of all cables in the Unit 2 cable tunnel.
Close inspection revealed that the EHC fluid had not permeated through the PVC overall jacket.
Since butyl rubber is not affected by EHC fluid, it was'reccmmended that these cables be cleaned and left in place after the cable pans were cleaned out.
The instrumentation cables as described abov in cases 2 and 3 revealed that some saturation through the overall PVC jacketing resulted.
- However, in no cases had the EHC fluid permeated through the mylar shielding covering, it was recommended that the plasticized sections of jacketing be removed and a suitable jacketing tape be applied.
Case 4 as described above, consisted of coaxial nuclear instrumen:atien cables.
The coaxial cables' overall Jacketing Is very thin and consequently suffered greatly frem the effects of plastici:stion.
Plastici:ation had exposed the shieldino conductor, such that possible electrical interference could resul t.
The coaxial cables' functions were as folicws:
1.
Local Pcwer Range Monitoring (LPRM)'
2.
Intermediate Range Mcnitoring (IRM) 3 Source Range Monitoring (SRM)
Since there were only 90 coaxial cables affected by the EHC fluid, it was recommended to splice in new coaxial cable sections and not tape over the shielding.
Splicing in this case was considered more acceptable than taping.
All coaxial cables were identified and labeled before splicing was permitted.
The ceaxial cables were tes ted agains: acceptable electrical properties---- --
after being spliced.
Figure l'shows the approximate locations where EHC fluid accumulated.
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Figure 2 illustrates the postulated path of EHC fluid migration from the EHC fluid reservoir to the Uni: 2 cable tunnel area.
The a:cumula tion of EHC fluid around the EHC fluid reservoir foundation, and subsequent migration between the finish ficer and rough slab, via small cracks in the concrete, is the postulated cause of the EHC fluid problem.
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. -3 The rough slab serves as the ceiling in the Unit I cable tunnel and minor small cracks ir the ceiling served as a leak path out of the concrete and 9nto the cable trays and floor.
Portions of cables within these trays
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thus became sa turated wi th the EHC fluid.
The upper cable trays did not contain all of the EHC fluid, even though the pans in the cable tunnel were of solid bottem construction.
This was because the EHC flui,d had leaked through the cable pan connecting joints and thus all the cable pans below were subjected to the EllC fluid.
The cables closest to the bottem of the cable pans were most affected by the EHC fluid because these cables were in constant saturation with EHC fluid.
At the pre ~sent time, all the cables in hhe affected area of the Unit 2 cable tunnel are being protected from the continuing EHC fluid leakage.
The leakage has subsided and once it has stopped the ceiling area will be cleaned and a protective sealer will be applied to prevent any possible leakages.
The EHC fluid reservoir foundation must also be sealed with the same protective sealer once leakages have been resolved.
The sealer has been ordered frem the Carboline Company, type 187 HFP,.which is a recommended EHC fluid sealant.
The station's technical staff has been performing a weekly inspection of the Unit 2 cable tunnel to assure that there is no leaking cnto the cables.
A representative from the Region Ill, U. S. Nuclear Regulatory Ccmmission reviewed the work package associated with the repairs and discussed his findings with the station.
If further information is desired, please contact the. station.
Sincerely yours, d$f.
/f./'
N. J. Kalivianakis Station Superintendent Quad-Cities Nuclear Power Station NJK/LLH/lk b
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FIGURE. I UNIT 2 CA8LE TUNNEL PARTI AL PL AN UNIT 2 EH C OIL RESERV0lR (ELEV. 595')
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