United States Nuclear Regulatory Commission - Protecting People and the Environment

IE Circular No. 77-06, Effects of Hydraulic Fluid on Electrical Cables


                               April 1 1977 

MEMORANDUM FOR:     J. P. O'Reilly, Director, Region I 
                    N. C. Moseley, Director, Region II 
                    J. G. Keppler, Director, Region III 
                    E. M. Howard, Director, Region IV 
                    R. H. Engelken, Director, Region V 

FROM:               Dudley Thompson, Acting Director, DFO, IE 


The subject document is transmitted for issuance by close of business five 
days after date of this letter. The Circular should be issued to all holders
of Construction Permits or Operating Licenses for Power Reactors. Also 
enclosed is a draft copy of the transmittal letter. 

                                        Dudley Thompson, Acting Director 
                                        Division of Field Operations 
                                        Office of Inspection and Enforcement

1.   Circular 77-06
2.   Draft transmittal letter

CONTACT:  J. B. Henderson 
          x 27421 


To all applicants for, or holders of, Construction Permits or Operating 
Licenses for Power Reactors 

     The enclosed Circular is being distributed for information in the 
belief that the subject matter is of sufficient safety significance to 
warrant specific attention. A reply is not requested. 

                                        (Regional Director) 

  "Effects of Hydraulic Fluid
   on Electrical Cables" 

IE Circular 77-06                                       Date:             
Page 1 of 1 



Commonwealth Edison Company, by letter to the NRC dated April 1, 1976, (copy
enclosed), described the circumstances under which fire resistant hydraulic 
fluid had a deleterious effect on the insulation and jacketing of electrical
cables. While the solvent characteristics of phosphate-ester fire resistant 
fluids are well documented in literature, it appears that this information 
may no be generally available to nuclear power plant operating staffs. Our 
evaluation of this occurrence emphasizes the importance of: 

1.   Reviewing design and operating procedures for systems containing 
     synthetic hydraulic fluids and other potentially aggressive fluids to 
     minimize the probability of leakage, overflow or inadvertent spill or 

2.   Reviewing housekeeping practices to assure that they provide for prompt
     cleanup of spills or leakage of any type of fluid. 

Letter from Commonwealth Edison Co.
  to J. Keppler, Director, Region III
  dtd. 4/1/76

          Commonwealth Edison 
          Quad-Cities Nuclear Power Station 
          Post Office Box 216 
          Cordova, Illinois 61242 
          Telephone 309/654-2241 


April 1, 1976 

J. Keppler, Regional Director
Office of Inspection and Enforcement
Region III
U. S. Nuclear Regulatory Commission
799 Roosevelt Road
Glen Ellyn, Illinois 60137 

Reference:  Quad-Cities Nuclear Power Station
            Docket No. 50-265, DPR-30, Unit 2 

In response to your Inspection Report No. 050-265/76-04, the following 
report concerning possible related to Electro-Hydraulic submitted. 

On October 9, 1975, station personnel were cleaning up EHC fluid which had 
been dripping on the Unit 2 cable tunnel floor. It was noticed not only had 
the EHC fluid been leaking onto the floor but also it had been leaking onto 
the cables in the surrounding cable pans. Closer-inspection of the cables 
revealed puffing and plasticization of cables that the EHC fluid had made 
contact with. At the time of discovery, Unit 2 was in the cold shutdown 

Cables in the Unit 2 cable tunnel were utilized for both safety related and 
non-safety related functions. The EHC fluid leak had not rendered any safety
or non-safety related systems inoperable. 

The immediate action taken was to determine the extent of plasticization of 
the affected cables. All the cables and cable pans in the affected area of 
the Unit 2 cable tunnel were cleaned with a soap and water solution as 
recommended by information from the EHC fluid manufacturer. The cleaning of 
EHC fluid from the cables should eliminate further effects of 
plasticization. A small section of control cable, which was hand traced to 
identify its function, was cut out and analyzed. It was discovered that only 
the overall jacketing material had been affected by the EHC fluid. 

Various cable manufacturers and the manufacturer of EHC fluid were consulted
as to the effects of EHC fluid on various polymers used for cable. 
Polyvinylchloride (PVC) and neoprene were found to be affected severely by 
EHC fluid and not recommended for use around EHC fluid. Other polymers such 
as polyethylene, teflon, silicone rubber, nylon, and butyl rubber were 
acceptable for use around EHC fluid. 


The next course of action was to determine the types of cable in the Unit 2 
cable tunnel that were affected by the EHC fluid. The type of cable 
construction were categorized as follows: 

1.   Control & Power (low voltage): lndividual 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.   Instrumentation: PVC jacketed, polyethylene insulated, coaxial cable. 

The control and power cables comprised 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 recommended that these cables be cleaned and 
left in place after the cable pans were cleaned out. 

The instrumentation cables as described above 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 instrumentation 
cables. The coaxial cables overall jacketing is very thin and consequently 
suffered greatly from the effects of plasticization. Plasticization had 
exposed the shielding conductor, such that possible electrical interference 
could result. The coaxial cables functions were as follows: 

1. Local Power Range Monitoring (LPRM) 

2. Intermediate Range Monitoring (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 coaxial cables were tested against acceptable electrical 
properties after being spliced. 

Figure 1 shows the approximate locations where EHC fluid accumulated. Figure
2 illustrates the postulated path of EHC fluid migration from the EHC fluid 
reservoir to the Unit 2 cable tunnel area. The accumulation of EHC fluid 
around the EHC fluid reservoir foundation, and subsequent migration between 
the finish floor and rough slab, via small cracks in the concrete, is the 
postulated cause of the EHC fluid problem. 


The rough slab serves as the ceiling in the Unit 2 cable tunnel and minor 
small cracks in the ceiling served as a leak path out of the concrete and 
onto the cable trays and floor. Portions of cables within these trays thus 
became saturated with 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 bottom construction. This was because
the EHC fluid had leaked through the cable pan connecting joints and thus 
all the cable pans below were subjected to the EHC fluid. The cables closest 
to the bottom of the cable pans were most affected by the EHC fluid because 
these cables were in constant saturation with EHC fluid. 

At the present time, all the cables in the 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 

The EHC fluid reservoir foundation must also be sealed with the same 
protective sealer once leakages have been resolved. The sealer has been 
ordered from 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 onto the cables. 

A representative from the Region Ill, U. S. Nuclear Regulatory Commission 
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, 

N. J. Kalivianakis
Station Superintendent
Quad-Cities Nuclear Power Station


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