ML20213D443
| ML20213D443 | |
| Person / Time | |
|---|---|
| Site: | Byron  |
| Issue date: | 11/05/1986 |
| From: | Ainger K COMMONWEALTH EDISON CO. |
| To: | Harold Denton Office of Nuclear Reactor Regulation |
| References | |
| 2356K, NUDOCS 8611120103 | |
| Download: ML20213D443 (4) | |
Text
-
t
'7m
/
T Commonwealth Edison f One First National Plaza, Chicago, Illinois
\\
/ Address Reply to: Post Office Box 767 w/ Chicago, Illinois 60690 0767 November 5, 1986 Mr. Harold R. Denton, Director Office of Nuclear Reactor Regulation U.S. Nuclear Regulatory Commission Washington, DC 20555
Subject:
Byron Station Units 1 and 2 plant Effluent Sampling NRC Docket Nos. 50-454 and 50-455 Reference (a): August 17, 1984 letter from T. R. Tramm to H. R. Denton
Dear Mr. Denton:
Reference (a) discussed our plans to resolve a concern regarding provisions for sampling gaseous radioiodine. The concern involved a 1/4" diameter high range sample line which may not provide a representative sample under all circumstances.
Modifications are being made to the Units 1 and 2 wide range gas stonitors. The modifications will allow auxiliary building vent stack samples to be drawn through one set of isokinetic nozzles and one 3/4" heat traced sample line for both low and mid/high range operating conditions. Attachment A contains a detailed description of the modifications to the wide range gas monitors.
Assuming these modifications are acceptable to the NRC staff, in accordance with Byron Unit 1 Operating License NPF-37, Condition 2.C.8, the modifications will be installed prior to startup following the first refueling outage. The modifications are common to Units 1 and 2 and therefore, will resolve the concern on Unit 2.
Please direct any questions regarding this matter to this office.
One signed original and fifteen copies of this letter and attachment are provided for NRC review.
Very truly yours, K. A. Ainger Nuclear Licensing Administrator 1m Attachment cc: Byron Resident Inspector 3oci 235CK B611120103 861105 II PDR ADOCK 05000454
\\\\
PDR p
(
ATTACHMENT A pursuant to our letter of August 17, 1984 (T.R. Tramm (CECO) to H.R. Denton (NRR)) regarding Plant Effluent Sampling and the replacement of the 1/4" diameter high range sample line and in fulfillment of the Byron Unit 1 Facility Operating License No. NPF-37, Condition 2.C.8, modifications have been designed and released for installation on the Units 1 and 2 Wide Range Gas Monitors. These modifications will be installed prior to startup following the first refueling outage for Byron Unit 1.
For each Wide Range Gas Monitor, the modification will allow auxil-iary building vent stack samples to be drawn through one set of isokinetic nozzles and one 3/4" heat traced sample line for both low and mid/high range operating conditions at the constant flow rate of 1.67 SCFM. The previous design used a 3/4" heat traced sample line for normal sampling by the high flow sample path at a flow rate of 1.67 SCFM and a 1/4" heat traced sample line for accident sampling by the low flow sample path at a flow rate of 0.06 SCFM.
In order to achieve the constant 1.67 SCFM flow rate in the 3/4" sample line, an auxiliary pump skid with automatic isokinetic flow control will be added per the modification and connected to the 3/4" heat traced sample line near the inlets to the sample conditioning skid by a flow splitter manifold (refer to Figure 1).
The auxiliary pump will be started automatically by the radiation monitors microprocessor (RM-80) when the high flow sample line is interrupted and stopped when the high flow sample pump is restarted. The flow splitter manifold either directs the entire sample line flow (1.67 SCPM) to the high flow sample path during low range operation when the high flow path sample pump is operating or directs a sample flow (0.06 SCFM, which is isokinetically collected from the 1.67 SCFM bypass flow going to the auxiliary pump skid) to the low flow sample path during mid/high range operation when the low flow path sample pump and auxiliary pump are running.
In tummary, and as stated previously, the modification to the Wide Range Gas Monitor sample lines will allow a single 3/4" sample line to be used under all conditions thereby eliminating the 1/4" sample line entirely. Use of the commonly accepted 3/4" sample line will contribute to the improvement of the sample representativeness by virtue of its larger internal diameter and higher sample flow and velocity. The higher velocity (approximately 3 times the 1/4" sample line velocity) will also provide a side benefit of improved response time for the Wide Range Gas Monitor.
Additionally, use of the same sample line for the low and mid/high range sample paths will reduce the effects of sample line surface conditioning.
The previous sample line design would have required the 1/4" sample line surfaces to become conditioned upon startup after being out-of-service during low range channel operation.
I
(
% ^
.,\\.
s.,
~
Finally therefore, the concern raised by NRC in SSER 5, Subsection 11.5 which stated that the Byron Noble Gas Monitor saeple line design may not provide a representative sample as indicated by recent research into the deposition of airborne radioiodine on metal-surfaceb'has been addressed.
i s
I a
k
\\
s
\\
\\
t 2356K
- o[
1t SAMPLE RETURN FLOW
~
fyMpS iD I
U R
+--+
CONTROLLER f
ASSEMBLY ah 1.67 SCFM I
1.67 SCFMl O ISOKINETIC 1.67SCFM N0ZZLES g
SAMPLE D
~
SAMPLE
[
CONDITIONING 0.06SCFMl 7 SKID 0.06 SCFM DETECTION SKID FLOW SPLITTER d L d i MANIFOLO c,
1 l
l l
-J r- -
/
l 1
i FLOW ELEMENT l
l l
CONTROL ROOM '
h DISPLAY I
--i l
TRANSMITTER RM-23 l
RM-80 JUNCTION BOX L- +
JUNCTION BOX
-4
- -- 4 MODULE ASSEM8LY
_j t
CONTROL ROOM CABINET Fig. 1.
WRGM system configuration
\\
t s
k
-. - - -., - ~. - _ _., - -. - - -.,, - -.. - - -,
-