United States Nuclear Regulatory Commission - Protecting People and the Environment

Information Notice No. 83-75: Improper Control Rod Manipulation

                                                            SSINS No.: 6835 
                                                            IN 83-75       

                                UNITED STATES
                        NUCLEAR REGULATORY COMMISSION
                    OFFICE OF INSPECTION AND ENFORCEMENT
                           WASHINGTON, D.C., 20555
                                     
                              November 3, 1983

Information Notice No. 83-75:   IMPROPER CONTROL ROD MANIPULATION 

Addressees: 

All nuclear power reactors holding an operating license (OL) or construction
permit (CP). 

Purpose: 

This information notice is provided as a notification to licensees of 
improper control rod manipulations. The improper manipulations were used 
because of inadequate communications from and controls by plant management. 
It is expected that recipients will review the information for applicability
to their facilities. 

Description of Circumstances: 

On March 10, 1983, Unit One at Quad Cities Station was being shut down in 
preparation for a weekend maintenance outage. The operators were inserting 
rods using what they thought was an approved "fast shutdown sequence" 
provided by the station nuclear engineers. They were actually using a rod 
worth minimizer (RWM) computer printout that had been attached to the 
approved sequence. The RWM computer printout listed the rod groups to be 
inserted in reverse order of the actual sequence required. 

As the shutdown continued the operators attempted to activate the RWM 
according to the normal unit shutdown procedure. The RWM immediately 
produced a rod block and indicated that rod insertion errors had occurred. 
After discussing the situation with the shift supervisor, it was decided 
that the RWM should be declared inoperable and bypassed. 

The shutdown continued with the shift supervisor acting as the independent 
rod verifier using the RWM computer printout as the assumed correct 
sequence. At approximately 10% power, the turbine generator was tripped and 
the reactor was manually scrammed as part of the normal shutdown. On the 
following morning, March 11, 1983, plant management discovered that the 
control rods had been inserted in reverse order using the RWM computer 
printout. 

On July 14, 1983, Hatch Unit 2 was operating at about 25% power, following a 
startup after a refueling outage, when condenser vacuum began to decrease. 
It was apparent to the plant operators that there was a problem with the 
steam jet air ejector and reactor power would have to be decreased to start 
a mechanical vacuum pump to prevent the loss of a reactor feed pump and a 
reactor 


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                                                           IN 83-75        
                                                           November 3, 1983 
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scram. The operators began to insert rods using the approved rod sequence, 
but because of the low worth of the control rods in this portion of the 
sequence, the power was not being decreased at the desired rate. At this 
time a decision was made by licensed operators and the shift technical 
advisor to insert rods using the Rod Out Notch Override Switch in the 
emergency in position and by individually scramming rods from the scram test 
panel. The operators did not have any approved procedure for this type of 
shutdown and defeated the rod sequence control system (RSCS) and the RWM. 
When the mechanical vacuum pump was put into service at a reduced power 
level and the vacuum had stabilized, an operator found a control rod in an 
out-of-sequence position, The operator then manually scrammed the unit 
following a plant procedure concerning out-of-sequence control rods. 

Discussion: 

The events, described above did not result in fuel damage, but affected the 
plants' ability in a rod drop accident. The control rod sequence, the RWM, 
and the RSCS are all used to mitigate the consequences of a control rod drop
accident. The misuse of these protective features could result in fuel 
damage. Plant managers should train and properly communicate to their 
operators the importance of these protective features and the adherence to 
approved rod sequence procedures. 

No written response to this notice is required. If you have any questions 
regarding this matter, please contact the Regional Administrator of the 
appropriate NRC Regional Office, or this office. 


                                   Edward L. Jordan Director 
                                   Division of Emergency Preparedness 
                                     and Engineering Response, IE 

Technical Contact:  Paul R. Farron, IE
                    (301) 492-4766

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