Information Notice No. 81-01: Possible Failures of General Electric Type HFA Relays

                                                            SSINS No.: 6835 
                                                            Accession No.: 
                                                            8011040254     
                                                            IN 81-01       

                                UNITED STATES
                        NUCLEAR REGULATORY COMMISSION
                    OFFICE OF INSPECTION AND ENFORCEMENT
                           WASHINGTON, D. C. 20555
                                     
                              January 16, 1981

Information Notice No. 81-01:   POSSIBLE FAILURES OF GENERAL ELECTRIC 
                                   TYPE HFA RELAYS 

Purpose: 

The intent of this Information Notice is to alert licensees and holders of 
construction permits of a potentially generic problem involving defective 
coil spools used in General Electric (GE) type HFA relays. Such defective 
relays were recently found at Turkey Point Unit 4 (Docket No. 50-250). 

Description of Circumstances: 

The defective coil spools are fabricated of either black or clear Lexan, a 
polycarbonate material that is susceptible to surface cracking when exposed 
to hydrocarbons. The concern here is that such surface cracks could 
ultimately deteriorate to such a degree that relay actuation would be 
blocked by the resultant debris, thereby inhibiting a required safety 
function. 

Indications of the above mentioned cracks were recently detected on the HFA 
relays used to sequence the emergency loads on the diesel generators at 
Turkey Point Unit 4 upon a loss-of-coolant accident coincident with a loss 
of offsite power. After detecting the cracks, the spare coils in the 
storeroom were inspected and, although these coils are new units, one was 
found to be cracked. The possible failures of GE type HFA relays highlights 
two salient points: (1) HFA relays have had a long history of failures 
(e.g., GE has issued several Service Information Letters (SIL) addressing 
these relays, the oldest one of which dates back to 1973, and it is 
anticipated that GE will issue a new SIL in the near future addressing this 
new concern); (2) the cracking phenomena seems to be similar to that 
experienced on the cam followers used on GE type SBM switches (e.g., these 
cam followers are fabricated of Lexan, and after their exposure to 
hydrocarbons during fabrication or during maintenance severe cracking 
resulted. See Information Notice No. 80-13 for additional details.) 

The above information identifies means whereby the integrity of a major 
safety-related system can be jeopardized or compromised by the blocking of 
relay actuation. Accordingly, this Information Notice is provided as an 
early notification of a possibly significant matter that is still under 
review by the NRC staff. Recipients should, therefore, review the 
information for possible applicability to their facilities. Although no 
specific action or response is requested at this time, further licensee 
actions may be requested or required pending the outcome of the NRC staff 
evaluation. 

If you have any question regarding this matter, please contact the director 
of the appropriate NRC Regional Office.