TXX-7054, Final Deficiency Rept CP-87-118 Re Steam Generator Blowdown Isolation.Initially Reported on 871023.Use of non-nuclear Safety Detection & Control to Isolate Steam Generator Blowdown Lines Not Deficiency in Design or Const
| ML20237D961 | |
| Person / Time | |
|---|---|
| Site: | Comanche Peak  |
| Issue date: | 12/14/1987 |
| From: | Counsil W TEXAS UTILITIES ELECTRIC CO. (TU ELECTRIC) |
| To: | NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM) |
| References | |
| CP-87-118, TXX-7054, NUDOCS 8712280056 | |
| Download: ML20237D961 (2) | |
Text
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Log #.TXX-7054,
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File # 10110 E
3 903.6 Ref. # 10CFR50.55(e)
M# ELECTRIC l'
December 14, 1987
.wimam c. counsu l
Emytive Vice Pressdent V. S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, D. C.
20555
SUBJECT:
COMANCHE PEAK STEAM ELECTRIC STATION (CPSES)
DOCKET N05. 50-445 AND 50-446.
STEAM GENERATOR BLOWDOWN ISOLATION SDAR: CP-87-118 (FINAL REPORT)
Gentlemen:
On October 23, 1987, we verbally notified your Mr. R. F. Warnick of a deficiency identified during the design validation review involving the use of non-nuclear safety (NNS) detection and controls to isolate the steam generator blowdown lines following a steam generator blowdown line break. We have determined that this condition is not reportable under the provisions of 10CFR50.55(e).
This is our final report on this issue.
The steam generator blowdown isolation scheme utilizes NNS flow switches to detect high flow conditions resulting from a steam generator blowdown line break. One flow switch is installed in each steam generator blowdown line downstream from the containment isolation valves.
Each flow switch has a normally closed contact that opens on high flow and deenergizes two safety-related relays.
Deenergizing the relays associated with any one 44cw switch will close all eight steam generator blowdown line isolation valves.
It was initially perceived that this use of NNS detection and control to mitigate the effects of a steam generator blowdown line break was unacceptable.
A steam generator blowdown line break will not result in.a trip of the turbine-generator or reactor protection system before the NHS detection and l
controls isolate the steam generator blowdown lines.
Therefore,-a loss of offsite power need not be assumed during detection and mitigation and all-available systems may be employed to mitigate.the consequences of a postulated piping failure in accordance with Branch Technical Position, BTP ASB 3-1 (formally APCSB 3-1).
Hence, the use of NNS detection and control to isolate.
the steam generator blowdown lines is not a deficiency in design or construction which could adversely affect safe operations, and is not reportable under 10CFR50.55(e).
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8712280056 871214 P7R ADOCK 05000445
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DCD t/o 400 North Ohve St: vet LB 81 Dallas. Texu.7520I.
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TXX-7054 December 14, 1987 Page 2 of 2 Records supporting these conclusions are available for review by your inspectors at the CPSES plant site.
Very truly yours,
$YLO W. G. Counsil HAM /grr c - Mr. R. D. Martin, Region IV Resident Inspectors, CPSES (3)