ML20098F044
| ML20098F044 | |
| Person / Time | |
|---|---|
| Site: | Byron, Braidwood, 05000000 |
| Issue date: | 09/25/1984 |
| From: | Tramm T COMMONWEALTH EDISON CO. |
| To: | Harold Denton Office of Nuclear Reactor Regulation |
| References | |
| 9221N, NUDOCS 8410020259 | |
| Download: ML20098F044 (2) | |
Text
.;
/*
~
['N Commonwealth Edison
/
One First Nitiond Plua. Chic;go, Ilknois k ~
")J Addr:ss R: ply ta: Post Ofhc3 Box 767
\\
/ Chicago, Illinois 60690 September 25, 1984 q ! ks Mr. Harold R. Denton, Director Office of Nuclear Reactor Regulation U.S. Nuclear Regulatory Commission Washington, DC 20555 Sub ject:
Byron Generating Station Units 1 and 2 Braidwood Generating Station Units 1 and 2 Instrumentation for the Detection of Inadequate Core Cooling NRC Docket Nos. 30-454/455 and 50-456/457,.
References (a):
July 6, 1984, letter from T. R. Tramm to H. R. Denton (D).
August 20, 1984, letter from T-T. Tramm to H. R. Denton
Dear Mr. Denton:
This is to inform you of our schedule for completing the installation of the subcooling margin display on Byron 1 prior to initial criticality.
This instrumentation is expected to be ready for operation
' on the other Byron and Braidwood units at the time of fuel load even
~
though it cannot be made operational until the reactor head is installed on the' vessel.
additional information on this instrumentation is also being1 p,rovided.
At Byron and Braidwood the primary display of subcooling is on a CRT atuthe operator's console.
Subcooling can also be determined manually from_hard-wired meters on the main control board as described in reference (a).
Present schedules indicate that the installation and testing of the computer software which produces the primary display may not be completed prior to October 15, 1984.
The instrumentation for manual backup subcooling' determination will be available at fuel load but the computer display will not be available until initial criticality.
i
'This is considered acceptable because subcooling determinations are not important until _ decay heat and a significant fission product inventory are present.
The subcooling instrumentation would not be operational during fuel loading anyway because the reactor vessel head must.be. installed before the thermocouples are in position to indicate core temperature.
In this situation reliance upon manual subcooling determinations is entirely adequate.
hokk[0 g
f)
^
~nr -
,.r.
H..R.:Denton September 25, 1984 A correction is necessary to the descriptions of the subcooling
-margin monitor provided in references (a) and (b).
The subcooling indication will be available at all times on the SPDS displays, both wide and narrow range.
The operator selects the display.for the appropriate
-plant conditions.
The narrow range provides information on plant safety status during power operations (Mode 1).
The wide range provides infomation for Modes 1-5.
As. indicated in reference (b), the implementation letter report on the instrumentation for the detection of inadequate core cooling will be submitted as soon as possible.
This report will be submitted prior to
-exceeding 5% power on Byron 1.
Please address questions regarding this matter to this office.
Very truly yours, f $s f.46 w T. R. Tramm Nuclear Licensing Administrator 1m s
9221N L'