Part 21 Report - 1995-010
ACCESSION #: 9611150608
LICENSEE EVENT REPORT (LER)
FACILITY NAME: COOPER NUCLEAR STATION PAGE: 1 OF 4
DOCKET NUMBER: 05000298
TITLE: Improper installation and calibration of Kaman normal and
high range gaseous activity detectors due to personnel
error.
EVENT DATE: 9/30/94 LER #: 94-025-00 REPORT DATE: 11/04/94
OTHER FACILITIES INVOLVED: DOCKET NO: 05000
OPERATING MODE: N POWER LEVEL: 0
THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR
SECTION:
Voluntary
LICENSEE CONTACT FOR THIS LER:
NAME: Alan J. Horn Staff Support Engineer
Nuclear Licensing an Safety TELEPHONE: (402) 825-3811
COMPONENT FAILURE DESCRIPTION:
CAUSE: N/A SYSTEM: N/A COMPONENT: N/A MANUFACTURER: N/A
REPORTABLE NPRDS: NO
SUPPLEMENTAL REPORT EXPECTED: NO
ABSTRACT:
Information obtained at a Kaman Users Group meeting indicated that the
positioning of the gaseous activity detectors affects their accuracy.
Plant staff subsequently determined that these detectors have been
improperly installed in monitors in various process system sample flow
paths. Preliminary information from the current equipment vendor
indicates that the as-found detection error ranges up to approximately 55
percent. As a result of further discussions with the current equipment
vendor it was also determined that an improper method has been used for
calibration of most Kaman detectors. The source used in the calibration
device has been used with its storage planchet, whereas, the
manufacturer's procedure uses the source without the planchet. The
vendor has indicated that this discrepancy may result in approximately a
5 to 9 percent non-conservative calibration error. This report is being
made for potential generic implications.
The root cause of these deficiencies is personnel error in not fully
understanding system configuration needs and not properly translating
vendor requirement
Plant Status
The plant was in Cold Shutdown with the Reactor Coolant System
temperature approximately 110 degrees Fahrenheit and the Residual Heat
Removal system in the Shutdown Cooling mode of operation when the
improper installation and calibration was identified.
Event Description
On September 24, 1994, after attending a Kaman Users Group meeting that
provided information that detector positioning affects their accuracy, it
was discovered that Kaman gaseous activity high range detectors (EIIS:
RE) were not properly installed. The high range G-M tubes are required
to be positioned accurately in order to produce an appropriate response.
The effect on the detector output could be in either the conservative or
non-conservative direction. This condition was not considered reportable
since the effect on these detectors from this condition would result in
no significant decrease in detector efficiency. However, as discussed
below, the subsequent investigation into this deficiency revealed other
potential problems that the District considered reportable as an
indication of potential generic implications.
On September 30, 1994, it was discovered that Kaman normal range
detectors have been improperly installed in the process system sample
chambers. In particular, the normal range detectors have been inserted
into the chambers too far resulting in a lower sensitivity to any
activity present in the system. The lower sensitivity means that a
higher activity concentration is required to produce the same output as
for the detector installed in the correct position. This is in the non-
conservative direction. Preliminary information from the current
equipment vendor (Kaman no longer sells or supports this equipment)
revealed that the indication error ranges from approximately 20 percent
to 55 percent for the as-found configuration. However, it is not
possible to exactly quantify the error for past installation
configurations.
On October 18, 1994, as a result of discussions with the current vendor,
it was determined that an improper method has been used for Kaman normal
and high range detector calibration. The source has been used in the
calibration device with its storage planchet, whereas, the present
manufacturer's procedure places the source in the calibration device
without the planchet. A report produced by the current vendor in July
1992 regarding another utility's calibration anomalies determined that
this discrepancy may result in approximately a 5 to 9 percent non-
conservative calibration error.
TEXT PAGE 3 OF 4
Safety Significance
The Kaman radiation detectors affected by the installation and
calibration deficiencies are part of the gaseous effluent monitoring
(EIIS: IL,IP) of plant ventilation and exhaust systems, including the
Elevated Release Point (ERP) for the plant. The safety function of these
monitors is to provide indication to the operator whenever limits on the
release of radioactive material to the environs are reached or exceeded.
The monitoring systems affected by these deficiencies are not essential
to any transients or accidents although a backup means to take
representative samples exists.
The installation and calibration deficiencies do not prevent the monitors
from operating, but do affect their accuracy. Also, each Kaman normal
range monitor has an alert alarm setpoint that is 10 percent of the
Technical Specification alarm setpoint. The errors associated with the
installation and calibration deficiencies would cause an alert alarm to
be received at a higher activity value than expected, but the District
determined it would still be below the Technical Specification release
limit since the errors are not of a sufficient magnitude to exceed the
difference between the alert alarm value and the Technical Specification
release limit value.
The high range detectors are affected by the installation and calibration
errors to a lesser extent than the normal range detectors. As such, the
detectors would be useable, but any readings obtained for accident
monitoring would be subject to the approximate 5 to 9 percent non-
conservative calibration error and an unknown, though small, installation
error.
In addition, Technical Specifications allow the use of alternate methods
of monitoring each parameter when the monitors are determined to be
inoperable. Also, the Technical Specifications require monthly grab
samples of all effluents. Gross inconsistencies between the monitors and
the grab samples would have been identified and investigated. No
inconsistencies have been observed, which gives reassurance that no
safety significant issues existed.
Therefore, the safety significance of these deficiencies is minimal.
Past semiannual radioactive material release reports that are based, in
part, on records provided by the Kaman detectors have been considered for
possible revision due to these potential errors. However, past releases
have been a small fraction of Technical Specification limits, and,
therefore, the District will not revise these release reports.
TEXT PAGE 4 OF 4
Cause
The root cause for these deficiencies is personnel error in not fully
understanding system configuration needs and not properly translating
vendor requirements into plant installation (maintenance) and calibration
procedures. The deficiencies were exacerbated by a lack of detail in the
Kaman information available and Kaman no longer supporting this
equipment.
Corrective Action
Corrective action planned includes proper installation and calibration of
these detectors (including procedure changes). This corrective action
for the normal range detectors has been completed. Corrective action for
the high range detectors will be completed prior to startup, when they
will be required to be operable.
Also, a review of other Kaman detector installation and calibration
procedures for proper implementation of vendor requirements will be
completed.
Additionally, generic implications for other systems will be
investigated.
Similar Events
LER 94-003 Missing o-ring in high range gaseous radiation monitors
could have caused an inaccurate sample when the monitors
were required to operate.
ATTACHMENT TO 9411150608 PAGE 1 OF 1
COOPER NUCLEAR STATION
P.O. BOX 98, BROWNVILLE, NEBRASKA 68321
Nebraska Public Power District TELEPHONE (402) 825-3811
NLS940107
November 4, 1994
U.S. Nuclear Regulatory Commission
Document Control Desk
Washington, D.C. 20555
Dear Sir:
Cooper Nuclear Station Licensee Event Report 94-025 is forwarded as an
attachment to this letter.
Sincerely,
J. T. Herron
Plant Manager
JTH/nr
Attachment
cc: L. J. Callan
G. R. Horn
J. H. Mueller
R. G. Jones
R. A. Sessoms
K. C. Walden
INPO Records Center
NRC Resident Inspector
R. J. Singer
CNS Training
CNS Quality Assurance
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