United States Nuclear Regulatory Commission - Protecting People and the Environment

IE Circular 76-07 - Inadequate Performance by Reactor Operating and Support Staff Members Description of Circumstances

CR78007 

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

                                                  IE Circular 76-07        
                                                  Date:  December 17, 1976 
                                                  Page 1 of 3 

INADEQUATE PERFORMANCE BY REACTOR OPERATING AND SUPPORT STAFF MEMBERS DESCRIPTION OF CIRCUMSTANCES 

Increases in numbers of errors by members of the reactor operating and 
support staff at various licensed power reactor facilities have resulted in 
a number of incidents where the individual's contribution to the overall 
"defense in depth" approach to safety was reduced. 

A recent event of concern to NRC involved an inadvertent criticality at a 
boiling water reactor as follows: 

     During refueling activities at a BWR an inadvertent reactor criticality
     occurred due to operator error.  A shutdown margin test was being 
     conducted from the control room using an approved procedure.  This test
     calls for withdrawals of a high worth rod and a second rod diagonally 
     opposite from the high worth rod.  The licensed reactor operator 
     incorrectly selected the adjacent control rod and withdrew it until the
     reactor was automatically scrammed by the reactor protection system. 

Other examples of events of concern which represent a cross-section of such 
occurrences are listed below: 

Improper Reactivity Change/Power Distribution 

1.   Valving error between refueling water storage tank and spent fuel pool 
     lowered primary boron concentration. 

2.   Incorrect estimated critical position and failure to recognize 1/M plot
     indications resulted in criticality being achieved with control rods 
     below the insertion limits. 

3.   Leakage from secondary to primary side of steam generator through 
     failed tubes resulted from improper maintenance which led to primary 
     system boron dilution. 
     
4.   Personnel error and procedural inadequacies defeated an administrative 
     control established to preclude inadvertent criticality resulting in 
     the withdrawal of adjacent control rods. 

5.   Improper control rod movements resulted in fuel cladding failures. 
.

                                                 IE Circular 76-07        
                                                 Date:  December 17, 1976 
                                                 Page 2 of 3 

Improper Valve Lineups 

6.   Valving errors led to overpressurization of the reactor coolant system.

7.   Valving error prevented two control rod hydraulic control units from 
     being scrammed. 

8.   Valving error resulted in air ejector offgas monitor being isolated. 

9.   Valving errors resulted in drywell atmosphere monitoring equipment 
     being isolated. 

Improper Maintenance and Surveillance 

10.  Incorrect interpretation of a drawing resulted in a core boring 
     penetrating a condensate storage tank (CST) level indication line 
     resulting in a loss of CST water and automatic realignment of ECCS 
     systems. 

11.  Unauthorized offgas isolation valve wiring change resulted in an 
     explosion, personnel contamination, and injury. 

12.  An operating error resulted in a diesel generator being returned to 
     service in an inoperable condition. 

13.  A calibration error resulted in the high power reactor trip setpoints 
     on all four power range channels being set in a non conservative 
     direction. 

Although none of these events resulted in consequences affecting the public 
health and safety, a review of these and other incidents indicates the 
operating or support staff member can be a significant contributor to such 
events.  Insufficient attention to and knowledge of plant operating history 
and status can degrade the individual's contribution to the overall defense 
in depth approach to nuclear safety. 

Recognition of the individual's role by both the operator and management is 
a key element in the system for safe operation of nuclear reactors.  Renewed
emphasis is being requested to assure appropriate and continuing management 
attention to this important issue. 
.

                                                 IE Circular 76-07        
                                                 Date:  December 17, 1976 
                                                 Page 3 of 3 

ACTION TO BE TAKEN BY LICENSEE: 

Nuclear power reactor license conditions require that adequate procedures be
provided for the safe operation of the facility.  To assure these procedures
are being implemented, all operators of nuclear power reactor facilities 
with operating licenses are requested to take the following action: 

CONDUCT A REVIEW OF YOUR PLANS OR PROGRAMS WHICH ARE TO PROVIDE POSITIVE 
ASSURANCE THAT MEMBERS OF YOUR REACTOR OPERATING AND SUPPORT STAFF ARE, IN 
FACT, COMPLYING WITH THE SAFETY PROCEDURES YOU HAVE IN EFFECT AND THAT THEY 
ARE AWARE OF SAFETY RELATED INCIDENTS THAT HAVE OCCURRED AT YOUR FACILITY OR
SIMILAR FACILITIES.  Your review should include but not be limited to 
consideration of the following three matters: 

1.   Program for periodic shift and operator training whereby incidents 
     which occur at your facility as well as at other licensed reactors, 
     including all significant personnel errors, will be reviewed with the 
     objective of identifying "the lessons to be learned." 
     
2.   Procedures routinely implemented by knowledgeable individuals to 
     qualitatively assess the performance of the operating and support staff
     in such areas as adherence to operating procedures, use of systems 
     checklists, and implementation of component and system tagouts.  This 
     should include review of the degree to which operating procedures, 
     tagout procedures, and checklists require signoff, i.e., signature or 
     initials to verify proper completion and to identify the responsible 
     personnel. 

3.   Procedures for random backshift and weekend visits by management and 
     supervision to the facilities, to monitor and assess operations 
     including crew manning and performance, equipment status and plant 
     conditions. 

A report acknowledging completion of your review should be submitted within 
90 days to the Director of Regional Office and a copy should be forwarded to
the NRC Office of Inspection and Enforcement, Division of Reactor Inspection
Programs, Washington, D.C.  20555. 

Approval of NRC requirements for reports concerning possible generic 
problems has been obtained under 44 U.S.C. 3152 from the U.S. General 
Accounting Office.  (GAO Approval B-180225 (R0072), expires 7/31/77.) 

Page Last Reviewed/Updated Wednesday, July 09, 2014