United States Nuclear Regulatory Commission - Protecting People and the Environment

ACCESSION #:  9504110082

TO: NRC OPERATIONS CENTER

FROM: MAINE YANKEE ATOMIC POWER CO.

SUBJECT: CRACKED ROLL PIN HOUSING IN CAM FOLLOWER 
         (GE TYPE SBM CONTROL AND TRANSFER SWITCH)

TIME OF EVENT : FEBRUARY 28, 1995 , 1145 HRS.

WE HAVE EXAMINED 20 CONTROL SWITCHES ON THE MAIN CONTROL BOARD IN
THE
CONTROL ROOM.  EACH SWITCH HAS SOME TYPE OF PROBLEM WITH A CRACK
THAT IF
THE CRACK PROPAGATES TO A BREAK, POTENTIALLY ALLOWS THE CONTACT TO
DETACH
FROM THE CAM FOLLOWER.  IN ADDITION, A NEW SWITCH FROM STOCK WAS
EXAMINED
AND IT ALSO HAD EVIDENCE OF CRACKING. THESE SWITCHES ARE SAFETY
CLASS AND
NON-SAFETY CLASS AND HAD THEY BEEN FOUND DEFECTIVE (COMPLETE
SEPARATION)
WHILE THE REACTOR WAS AT POWER, IT COULD HAVE RESULTED IN THE PLANT
BEING
SERIOUSLY DEGRADED THAT SIGNIFICANTLY COMPROMISED PLANT SAFETY.
(10CFR50.72(b)(2)(i).

PRESENTLY THE PLANT IS IN A SHUTDOWN CONDITION WITH REACTOR
DEFUELED.
SPENT FUEL POOL COOLING IS IN SERVICE AND WITHOUT PROBLEMS. OUR
OUTAGE
RISK MANAGEMENT PROGRAM HAS CONTINGENCY PLANS IN PLACE TO
COMPENSATE FOR
ANY PROBLEMS WITH SPENT FUEL COOLING. (THE TIME TO BOIL IS 18 HOURS
WITH
A LOSS OF COOLING.) ADDITIONAL INFORMATION WILL BE SENT TO NRC VIA AN
LER
AS REQUIRED BY 50.73 (a)(2)(ii) AND 10CFR PART 21. THE RESIDENT NRC
INSPECTOR HAS BEEN INFORMED OF THE EXISTING PROBLEM.

                                             PSS: WILLIAM BAXTER

                                             STA: DAN McDOUGOLD


GE
                       INSTRUCTIONS               GEH-2038A
                                                SUPERCEDES GEH 2038
                                                  
                       CONTROL AND TRANSFER SWITCH

                    TYPE S B M
          
                             Figure omitted


                          SWITCHGEAR DEPARTMENT

                            GENERAL ELECTRIC

                            PHILADELPHIA, PA.


Figure 1 "Exploded View of Type Switch SBM Switch" omitted.



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