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.
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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.
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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 Thursday, March 25, 2021