United States Nuclear Regulatory Commission - Protecting People and the Environment

Information Notice No. 87-25: Potentially Significant Problems Resulting from Human Error Involving Wrong Unit, Wrong Train, or Wrong Component Events

                                              SSINS No.: 6835 
                                                 IN 87-25 

                                  UNITED STATES
                          NUCLEAR REGULATORY COMMISSION
                      OFFICE OF NUCLEAR REACTOR REGULATION
                             WASHINGTON, D.C.  20555

                                  June 11, 1987

Information Notice No. 87-25: POTENTIALLY SIGNIFICANT PROBLEMS RESULTING 
                                  FROM HUMAN ERROR INVOLVING WRONG UNIT, 
                                  WRONG TRAIN, OR WRONG COMPONENT EVENTS 

Addressees: 

All nuclear power reactor facilities holding an operating license (OL) or a 
construction permit (CP). 

Purpose: 

This information notice is provided to inform recipients of potentially 
significant problems resulting from human error involving wrong unit, wrong 
train, or wrong component events.  It is expected that recipients will review 
the information for applicability and consider actions, if appropriate, to 
preclude similar problems from occurring at their facilities.  Suggestions 
contained in this notice do not constitute NRC requirements; therefore, no 
specific action or written response is required. 

Description of Circumstances: 

On April 14, 1987, with Calvert Cliffs Unit 1 in Mode 5 and electrical 
terminal boxes open for equipment qualification work, plant personnel were 
attempting to use a portion of the containment spray system to fill the safety 
injection tanks.  In preparation for this, an operator had been sent to close 
a Unit 1 containment spray valve.  However, the operator mistakenly closed the
corresponding Unit 2 containment spray valve.  The inadvertent containment 
spray actuation resulted in approximately 4000 gallons of borated water being 
injected into the Unit 1 containment and created the potential for electrical 
equipment degradation due to wetting by borated water (boric acid intrusion). 

Discussion: 

A large number of reports have been made to the NRC that describe events 
resulting from human error involving actions performed on the wrong unit, 
wrong train, or wrong component.  A study published in January 1984 by the NRC 
Office for Analysis and Evaluation of Operational Data, "Human Error in Events
Involving Wrong Unit or Wrong Train," and supplementary reports on August 8, 
1984, February 13, 1986, September 19, 1986, and May 20, 1987, have identified
more than 200 events of this nature that have occurred since 1981.  The data 
indicate that there does not appear to be any substantial change in the rate 
of occurrence in events per reactor year, and that the rate of these events at

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plants with little operating experience seems to be higher than that at plants
with more experience.  Examples of recent events caused by human error 
involving the wrong unit, wrong train, or wrong component are described below. 

A study performed by the Office of Nuclear Reactor Regulation and reported in 
NUREG-1192, "An Investigation of the Contributors to Wrong Unit or Wrong Train
Events," indicates that some of the primary causes of the events studied were 
inadequate labeling of plant equipment, components, and areas; inadequate 
personnel training and experience, and inadequate procedures.  Examples of 
actions taken by licensees to help prevent recurrence of these types of events
are also given. 

Adequate procedures, planning, labeling, and training of personnel usually 
prevent such events from happening.  In addition, an independent verification 
program can assist in promptly identifying and correcting the misalignment of 
plant systems.  The frequency and number of such events being reported to the 
NRC suggest that industry needs to increase its attention in these areas. 

Additional Events: 

On May 13, 1986, with Kewaunee at power, personnel were performing a 
surveillance procedure on the power range nuclear instrumentation.  The 
protection signal bistables had been tripped to test Channel N44; however, a 
test signal simulating an increased power level was inadvertently input to 
Channel N43.  This created the necessary 2 out of 4 coincidence logic and the 
reactor tripped on simulated overpower (delta T). 

On January 11, 1986, with St. Lucie 2 at power, an operator was performing the
weekly turbine overspeed surveillance.  A manual turbine trip (and subsequent 
reactor trip) occurred when the operator inadvertently actuated the turbine 
trip lever instead of the test lever. 

On March 18, 1985, with Surry 1 and 2 at power, an operator assigned to "lock 
out" the automatic initiation of C02 portion of the fire protection system for
Fire Zone 8 (the Unit 2 containment penetration area) to facilitate 
construction activities, mistakenly "locked out" the C02  for Fire Zone #5 
(the Unit 1 cable vault), This error went undetected for approximately 10 
hours and resulted in a violation of the Technical Specifications (no fire 
watch in affected area). 

References: 

Information on independent verification programs is provided by IE Information
Notice 84-51, "Independent Verification." Information regarding inadvertent 
defeat of safety function caused by human error involving wrong unit, wrong 
train, or wrong component events is provided by Information Notice No. 84-58, 
"Inadvertent Defeat of Safety Function Caused by Human Error Involving Wrong 
Unit, Wrong Train, or Wrong System." 


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No specific action or written response is required by this information notice. 
If you have any questions about this matter, please contact the Regional 
Administrator of the appropriate regional office or this office. 



                             Charles E. Rossi, Director 
                             Division of Operational Events Assessment
                             Office of Nuclear Reactor Regulation 

Technical Contact:    Jack Ramsey, NRR
                      (301) 492-9081 

Attachment: List of Recently Issued NRC Information Notices 
Page Last Reviewed/Updated Tuesday, November 12, 2013