Protecting People and the EnvironmentUNITED STATES NUCLEAR REGULATORY COMMISSION
SSINS No.: 6835
IN 83-35
UNITED STATES
NUCLEAR REGULATORY COMMISSION
OFFICE OF INSPECTION AND ENFORCEMENT
WASHINGTON, DC 20555
May 31, 1983
Information Notice No. 83-35: FUEL MOVEMENT WITH CONTROL RODS WITHDRAWN
AT BWRS
Addressees:
All boiling water reactor facilities holding an operating license (OL) or
construction permit (CP).
Purpose:
This information notice is provided as a notification of potentially
significant events involving fuel loading in control cell locations where
control rods are not fully inserted. It is expected that recipients will
review the information for applicability to their facilities. No specific
action or response is required at this time.
Description:
Brunswick 1 Event
During a refueling outage on Saturday, January 22, 1983, five control rods
in empty cell locations were uncoupled from their drive mechanisms to permit
removal of the drives for maintenance. As work progressed, the rod drives
were recoupled with the control rods because of pressure fluctuations in the
rod drive fluid, thereby preventing the removal of the drive mechanisms from
the reactor vessel. To avoid having a maintenance crew idle, a decision was
made to proceed to other control rod drives requiring maintenance.
By 3:00 a.m, on January 23, the shift foreman, after consultation with the
nuclear engineer on shift, concluded that all applicable requirements had
been met for a temporary change to the existing fuel movement procedure. The
shift operating supervisor and the senior reactor operator on the refueling
bridge approved the temporary change to bypass some steps in the existing
procedure and proceed to the next 4 control cells requiring rod drive
maintenance. Each of the 4 control cells contained a fuel assembly. These
assemblies were subsequently moved to 4 other separate control cell
locations according to the fuel movement procedure.
During a routine rod position verification, approximately 9 hours after the
4 fuel assemblies were moved, it was discovered that the control rods in
those cells were fully withdrawn. As mentioned above, the fuel movements
were made in accordance with the as-written fuel movement procedure, but
apparently were not reviewed to ensure that the control rods were fully
inserted in those cells to which fuel was moved. These fuel movements were
in violation of the licensee's technical specifications.
8305110461
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IN 83-35
May 31, 1983
Page 2 of 3
Duane Arnold Event
During core loading operations on March 30, 1980, a fuel assembly would not
set properly in its assigned location in control cell, 06-19. A temporary
change was written to the fuel movement procedure to unload inspect, and
reload that control cell. Upon completion of the steps to the change of the
fuel movement procedure, the normal reload was resumed beginning with
control cell 06-23. The first fuel assembly was moved into control cell
06-23. Before a second fuel assembly could be loaded into control cell
06-23, it was discovered that the control rod in that cell was not fully
inserted. Inadvertently, the fuel movement procedure temporary change had
eliminated a step to insert the control rod in the next cell (06-23) to be
loaded. This fuel movement was in violation of the licensee's technical
specifications.
Discussion:
Refueling interlocks are specified for all BWRs to prohibit fuel loading
with any control rod withdrawn in order to prevent the possibility of
criticality during refueling operations. Operating plant technical
specifications have, however, allowed bypass of the refueling interlock
signals to facilitate multiple control rod drive maintenance. The bypass of
the refueling interlock signals was acceptable as long as several criteria
were met, including the removal of the fuel assemblies surrounding the
control rod to be withdrawn. Some technical specifications then evolved
through utility negotiations with the NRC to permit fuel loading with
control rods withdrawn. Subsequently the NRC issued the BWR Standard
Technical Specifications (NUREG-0123) which reflected this position.
Brunswick 1 operates under essentially standard technical specifications;
Duane Arnold operates under custom technical specifications. Both versions
allow fuel movement with multiple control rods withdrawn when specific
conditions are met.
General Electric recognized the potential problem in June 1982 and issued
SIL No. 372 to clarify the original intent of the GE BWR technical
specifications concerning refueling interlocks. It was recognized at this
time that the potential for localized criticality and fuel damage does exist
while loading fuel with control rods withdrawn for maintenance. General
Electric recommended that each licensee review its present technical
specifications and refuel and rod drive maintenance procedures and adopt the
concept of suspended fuel loading whenever all control rods are not fully
inserted.
The original intent of the refueling interlocks is to prohibit the loading
of fuel assemblies into the reactor vessel with multiple control rods
withdrawn. Some operating plant technical specifications do not allow fuel
loading in the reactor vessel with control rods withdrawn for maintenance
and other plants may want to reflect this position in their station
procedures. The NRC plans to reevaluate the Standard Technical
Specifications governing fuel movement with multiple control rods withdrawn
for maintenance.
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IN 83-35
May 31, 1983
Page 3 of 3
No written response to this information notice is required. If you need
additional information regarding this matter, please contact the appropriate
NRC Regional Office, or this office.
Edward L. Jordan Director
Division of Emergency Preparedness
and Engineering Response
Office of Inspection and Enforcement
Technical Contact: P. R. Farron
(301) 492-4766
Attachment:
Lit of Recently Issued Information Notices
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