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Bulletin 79-06A (Revision No. 1), Review of Operational Errors And System Misalignments Identified During The Three Mile Island Incident

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

                               April 18, 1979

                                                  IE Bulletin No. 79-06A 
                                                  (Revision No. 1) 

REVIEW OF OPERATIONAL ERRORS AND SYSTEM MISALIGNMENTS IDENTIFIED DURING THE 
THREE MILE ISLAND INCIDENT 

IE Bulletin 79-06A identified actions to be taken by the licensees of all 
pressurized water reactors designed by Westinghouse. 

Item No. 3 of the actions to be taken, as stated in the original bulletin, 
was: 

     "3.  For your facilities that use pressurizer water level coincident 
          with pressurizer pressure for automatic initiation of safety 
          injection into the reactor coolant system, trip the low 
          pressurizer level setpoint bistables such that, when the 
          pressurizer pressure reaches the low setpoint, safety injection 
          would be initiated regardless of the pressurizer level.  In 
          addition, instruct operators to manually initiate safety injection 
          when the pressurizer pressure indication reaches the actuation 
          setpoint whether or not the level indication has dropped to the 
          actuation setpoint." 

Information from licensees and Westinghouse has identified that 
implementation of this action would preclude the performance of surveillance
testing of the pressurizer pressure bistables without initiating a safety 
injection. 

In order to permit surveillance testing of the pressurizer pressure 
bistables, the low pressurizer level bistables that must operate in 
coincidence with the low pressurizer pressure bistables may be restored to 
normal operation for the duration of the surveillance test of that 
coincident pressurizer pressure channel.  At the conclusion of the 
surveillance test of each pressurizer pressure channel, the coincident 
pressurizer level channel must be returned to the tripped mode defined in 
Action Item 3 of IE Bulletin 79-06A. 

As a result, Item 3 should be revised as follows: 
.

IE Bulletin No. 79-06A                                      April 18, 1979 
(Revision No. 1)                                            Page 2 of 2 

     "3.  For your facilities that use pressurizer water level coincident 
          with pressurizer pressure for automatic initiation of safety 
          injection into the reactor coolant system, trip the low 
          pressurizer level setpoint bistables such that, when the 
          pressurizer pressure reaches the low setpoint, safety injection 
          would be initiated regardless of the pressurizer level.  The 
          pressurizer level bistables may be returned to their normal 
          operating positions during the pressurizer pressure channel 
          functional surveillance tests.  In addition, instruct operators to 
          manually initiate safety injection when the pressurizer pressure 
          indication reaches the actuation setpoint whether or not the level 
          indication has dropped to the actuation setpoint." 

Item 13 of the actions to be taken, as stated in the original bulletin, was:

     "13. Propose changes, as required, to those technical specifications 
          which must be modified as a result of your implementing the above 
          items." 

Long term resolutions of some of these required actions may require design 
changes.  Therefore, Item 13 of actions to be taken should be revised as 
follows: 

     "13. Propose changes, as required, to those technical specifications 
          which must be modified as a result of your implementing the above 
          items and identify design changes necessary in order to effect 
          long term resolutions of these items." 

For all light water reactor facilities designed by Westinghouse with an 
operating license, respond to Items 1-12 within 10 days of the receipt of 
this Bulletin.  Respond to Item 13 (Technical Specification Change proposals
and identification of design changes in 30 days.) 

The other requirements of IE Bulletin 79-06A remain in effect. 

Approved by GAO, B180225 (R0072); clearance expires 7-31-80.  Approval was 
given under a blanket clearance specifically for identified generic 
problems. 
Page Last Reviewed/Updated Tuesday, July 23, 2013