ML18051B423
| ML18051B423 | |
| Person / Time | |
|---|---|
| Site: | Palisades  |
| Issue date: | 06/10/1985 |
| From: | VANDEWALLE D J CONSUMERS ENERGY CO. (FORMERLY CONSUMERS POWER CO.) |
| To: | Office of Nuclear Reactor Regulation |
| References | |
| RTR-NUREG-0737, RTR-NUREG-737, TASK-2.F.2, TASK-TM GL-82-28, NUDOCS 8506170442 | |
| Download: ML18051B423 (2) | |
See also: IR 05000255/1985005
Text
.:..*._ .. consumers
Power company General Offices: 1945 West Parnell Road, Jackson, Ml 49201 * (517) 788-1636 June 10, 1985 Director, Nuclear Reactor Regulation
US Nuclear Regulatory
Commission
Washington, DC 20555 DOCKET 50-255 -LICENSE DPR-20 -PALISADES
PLANT -David J VandeWalle
Director of Nuclear licensing
CLARIFICATION
OF SUBCOOLING
MARGIN MONITOR OPERABILITY
REQUIREMENTS
Nuclear Regulatory
Commission (NRC) letter dated December 14, 1983 provided _Consumers
Power Company an evaluation
of our response to Generic Letter 82-28, "Inadequate
Core Cooling Instrumentation".
This NRC letter stated "the design of the presently
installed
subcooling
margin_monitor
is acceptable
contingent
on upgrading
of the input range from the pressure and temperature
sensors as committed
by the licensee".
Due to recent concerns of our Senior Resident Inspector
as documented
in Inspection
Report 50-255/85005, a clarification
of the operabiiity
requirements
for the subcooling
margin monitor is necessary.
Our Technical
Specifications
require that at least one channel of the subcooling
margin
be operable whenever primary coolant system temperature
is above 515°F. In addition to a continuous
digital display, the subcooling
margin monitor also includes an alarm function which is -common _to
of the two otherwise
independent
channels.
The alarm function of this monitor-is
not addressed
in our Technical
Specifications, but we do calibrate
the alarm during the performance
of the Technical
Specification
surveillance
procedure
for the subcooling
margin monitor. ' "Clarification
of TMI Action Plan Requirements", NUREG-0737, section II.F.2; Instrumentation
for Detection
of Inadequate
Core Cooling, item 5, requires that "the indication
must give advanced warning of the approach of ICC (Inadequate
Core Cooling)".
It is our understanding
that this requirement
is referencing
the composite
instrumentation
system for detection
of inadequate
core cooling. This system consists of a primary coolant inventory
monitoring
system, core-exit
thermocouples
and subcooling
margin monitor. Although the alarm function is 'incorporated
in our subcooling
margin monitor design and certainly
does provide advanced warning, an operable subcooling
margin monitor display, itself, also provides advanced warning of the approach of inadequate
core cooling, as does the coolant inventory
monitoring
system. In addition, there is no specific requirement
for an alarm function for the subcooling
OC0685-0003B-NL02 I ADOCK )
. " Director, Nuclear Reactor Regulation
Palisades
Plant Subcooling
Margin Monitor June 10, 1985 2 margin monitor in Appendix B of NUREG-0737, "Design and Qualification
Criteria for Accident Monitoring
Instrumentation".
For operability
declarations
as well as subsequent
reportability
determinations, we believe it is appropriate
to take credit for the operable display. Consequently, the inoperability
of the alarm function of the subcooling
margin monitor, for whatever reason, does not constitute
inoperability
of the subcooling
margin monitor provided that the subcooling
margin monitor detection
and display capabilities
are unaffected.
The alarm function should, however, be prudently
maintained
in an operable condition.
Director, Nuclear Licensing
CC Administrator, Region III, USNRC NRC Resident Inspector
-Palisades
OC0685-0003B-NL02