ML20207G628
| ML20207G628 | |
| Person / Time | |
|---|---|
| Site: | Braidwood  |
| Issue date: | 12/29/1986 |
| From: | Hunsader S COMMONWEALTH EDISON CO. |
| To: | Harold Denton Office of Nuclear Reactor Regulation |
| References | |
| 2556K, NUDOCS 8701070364 | |
| Download: ML20207G628 (3) | |
Text
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) Conunonwealth Edloon n One First National Plaza, Chicago, INinois
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Address Reply to: Post Office Box 767 Chica00, lHinois 60690 0767 December 29, 1986 Mr. Harold R. Denton, Director Office of Nuclear Reactor Regulation U.S. Nuclear Regulatory Commission Washington, DC. 20555
Subject:
Braidwood Station Units 1 and 2 Plant Effluent Sampling NRC Docket Nos. 50-456 and 50-457 Reference (a)
November 5, 1986 K.A. Ainger letter to H.R. Denton
Dear Mr. Denton:
Reference (a) provided the detailed description of the modifications being applied to the Byron Station Units 1 and 2 wide range gas monitors.
The purpose of this letter is to inform you that these modifications have been made at Braidwood Station Units 1 and 2.
Attachment "A" provides a description of the modifications installed at Braidwood and summarizes the improvements to the effluent sampling system.
Commonwealth Edison believes this submittal addresses the questions in this area for Braidwood Station.
Please direct any additional questions regarding this matter to this office.
One signed original and fifteen copies of this letter and the attachment are provide for your review.
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Very truly yours, l
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C. Hunsader Nuclear Licensing Administrator l
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J.
Stevens 00*l 2556K 1
8701070364 861229 8 I PDR ADOCK 05000456 l
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ATTACHMENT A The previous wide range gas monitoc 1esign 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.
The new design and modification 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 at the constant flow rate of 1.67 SCFM.
In order to achieve a constant 1.67 SCFM flow rate in the 3/4" sample line, an auxiliary pump skid with automatic isokinetic flow control has been 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 (refere 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 SCFM) 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.
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.
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ASSEMBLY ak 1.67 5CFM I
ISDKINETIC 1.67 SCFM l 1.67 SCFM N0ZZLES g
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0.06 SCFM l CONDITIONING SKl0 0.06 SCFM DETECTION SKl0 FLOW SPLITTER d L d i MANIFOLO c,
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FLOW TRANSMITTER g
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TRANSMITTER RM-23 l
RM-80 JUNCTION BOX 4
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-4 MODULE ASSE MB LY
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CONTROL ROOM CABINET Fig.
1.
WRGM system configuration l