ML20126A946
| ML20126A946 | |
| Person / Time | |
|---|---|
| Site: | Fort Saint Vrain  |
| Issue date: | 05/17/1985 |
| From: | Lee O PUBLIC SERVICE CO. OF COLORADO |
| To: | Johnson E NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV) |
| References | |
| RTR-NUREG-0737, RTR-NUREG-737, TASK-2.F.1, TASK-TM P-85179, TAC-57944, NUDOCS 8506130519 | |
| Download: ML20126A946 (4) | |
Text
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O Public Service-
- Ora P.O. Box 84o Denver, CO 80201-o840 OSCAR R. LEE VICE PRESIDENT May 17,1985 Fort St. Vrain Unit No. 1 P-85174 b $ b Oh. b %
l Regional Administrator g F- -
Region IV U.S. Nuclear Regulatory Commission JllN - 4 l985 611 Ryan Plaza Drive, Suite 1000 Arlington, Texas 76011
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Attn: E. H. Johnson Docket No. 50-267
SUBJECT:
NUREG-0737 II F.1.1 Noble Gas Accident Monitoring Instrumentation
REFERENCES:
- 1) G-84408, Johnson to Lee, dated 10/24/84
- 2) P-84506, Lee to Johnson, dated 11/28/84
- 3) P-84191, Warembourg to Johnson, dated 07/02/84
Dear Mr. Johnson:
In our letter of November 28,1984 (Reference 2), we indicated that it would be possible to use a detector being developed, rather than a dilution system.
During preliminary engineering, a review was done on various high range monitors considered for use to replace the existing reactor plant exhaust noble gas monitor.
Due to procurement, calibration, existing readout and design problems, it was decided to design the dilution system described in Reference 3.
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.Th2 di.lution system planned for installation is shown in Figura 1.
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flow rate of 90 SCFH is sampled from the reactor plant exhaust stack of which 0.3 SCFH is diluted with 60 SCFH of air drawn from the turbine deck. The final dilution factor is 201:1, which is a ratio of the total. flow through the monitor to the 0.3 SCFH stack flow.
.The flow rates are controlled by thermal mass sensors and controllers and the flowrates are displayed locally. This dilution rate results in a range of 1.3E-02 to 1.3E03 micro Ci/cc for RT-7324-2. The other existing monitor, RT-7324-1, has. a range of 2.45E-06 to 2.45E-01
. micro Ci/cc; giving an overlap of greater than one decade.
The continuous remote readout and the alarm will remain in the Control Room.
The monitor will be calibrated using current procedures (Kr-85 source). The flow controllers will be calibrated with a separate procedure and adjusted to maintain the air flows as close as possible to the desired dilution rate. The dilution factor will be combined with the results from calibration of the monitor to yield a sensitivity for the system. This sensitivity factor will be used the same as currently to convert the Control Room instrument readout from CPM. to micro Ci/cc.
The new compressors and flow controllers will be powered from non-interruptible power supplies.
'As indicated in Reference 2 (wherein we stated that we were evaluating both a new high range monitor and the dilution system) our original commitment date of the end of the 4th refueling outage remains unchanged.
If you have any questions or comments on this subject, please contact Mr. M. H. Holmes at (303) 571-8409.
Very truly yours, hV
- 0. R. Lee, Vice President Electric Production ORL/KD:pa J
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UNITED STATES OF AMERICA NUCLEAR' REGULATORY COMMISSION In the Matter
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Public Service Company of' Colorado Docket No. 50-267 Fort.St. Vrain Unit No. 1
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N AFFIDAVIT 0.
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Lee, being duly sworn, hereby deposes and says that he is Vice President of Public Service Company of Colorado; that he is duly authorized to sign and file with the Nuclear Regulatory Comission the attached response to NUREG-0737 II F.1.1; that he is familiar with the content thereof; and that the matters set forth therein are true and correct to the best of his knowledge, information and belief.
- 0. R. Lee Vice President STATE OF (M
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Subscribed and sworn to before me, a Notary Public on this 2rd day of bz
, 1985.
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