ML20154P146
| ML20154P146 | |
| Person / Time | |
|---|---|
| Site: | Fort Saint Vrain  |
| Issue date: | 05/27/1988 |
| From: | Robert Williams PUBLIC SERVICE CO. OF COLORADO |
| To: | NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM) |
| References | |
| GL-88-03, GL-88-3, IEB-85-001, IEB-85-1, P-88115, NUDOCS 8806030222 | |
| Download: ML20154P146 (5) | |
Text
h Public Service'
%* h May 27, 1988 P.O. Box 840 Fort St. Vrain Denver, co 80201- 0840 Unit No. 1 P-88115 R.O. WILLIAMS, JR.
VICE PRESIDENT NUCLEAR OPERATIONS U. S. Nuclear Regulatory Commission ATTN: Documer Control Desk Washington, D.L.
20555 Docket No. 50-267
SUBJECT:
Response
REFERENCE:
1)
Generic Letter 88-03, dated February 17, 1988 (G-88047) 2)
IE Bulletin 85-01, dated October 29, 1985 (G-85439)
Gentlemen:
Public Service Company of Colorado (PSC) has evaluated IE Bulletin 85-01 and Generic Letter 88-03 for applicability to the Furt St.
Vrain ( FSV) Nuclear Generating Station. Altnough these directives are addressed to Pressurized Water Reactor (PWR) licensees, PSC has anabzed the relevance of this guidance for the FSV High Temperature Gas Cooled Reactor (HTGR).
PSC has determined that steam binding
- concerns, as identified in IE Bulletin 85-01 and Generic Letter 88-l 03, have been precluded at FSV.
This conclusion is based upon the following:
Unlike a PWR, FSV does not utilize a standby auxiliary feedwater pump system to supply backup (emergency) water to the steam generator loops (2).
FSV is equipped with three boiler feedwater pumps (two steam turbine driven and one electric motor driven) installed in parallel.
The three pumps supply both the normal feedwater system and the emergency feedsater system through independent valves and neaders to the steam generators.
The majc.e difference between the two systems at FSV is that the nimal feedwater system preheats the water via two regenerative hea s downstream of the pumps while the emergency feedwater system does not employ these heaters.
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f P-88115 Page 2 May 27, 1988' The normal boiler feedwater pump net positive suction head (NPSH) is adequate for pressure swings:during load transients after -allowing for the pressure drop in the pump suction line.
Further NPSH protection for each pump is-provided with an automatic system that i
injects condensate to ensure that the pumo suction temperature is at least 15 degrees F below the saturation temperature during abnormal conditions.
Each pump is,srovided with a check valve and a motor operated stop-check valve on the discharge.
In
- addition, a
nonoperating steam generator loop.is isolated with control valves.
Low boiler feed pump flow is sensed by -a control system that automatically recirculates feedwater to -the _deaerator.
Therefore, this system is set to recirculate when a boiler feed pump is idle and this would also serve to protect _a pump from steam binding.
i Based on the above, steam backleakage into an idle boiler feedwater pump is not a concerr. at FSV.
)
In addition to the normal and emergency feedwater systems supplied by the three boiler feedwater pumps, the following alternate supplies of i
a seconda ry coolant are available to the steam generators as detailed i
J below:
The firewater system is normally isolated from the emergency l
feedwater system by a blind insert, If all other cooling water supplies are lost, the blind insert can be removed and replaced by a thru insert that will allow firewater flow through the emergency feedwater header.
- 2) Emergency Condensate Header supplied by:
j a)
Condensate (4 pumps) 4 1
The condensate pumps can supply water to either the ecor.omi ze r evaporator superheater sections or the reheater sections of the steam generators.
Various isolation and check valves are installed that prevent inadvertent steam binding of these pumps. Additionally, j
various combinations of these pumps run during normal plant operation.
b)
Firewater (2 pumps)
)
As additional backup, the discharge lines of the firewater I
j pumps are also connected to the emergency condensate header.
These are also protected from steam binding by the various I
I i
l
,Y
~
P-88115
'Page 3
-May 27, 1988 installed isolation and check valves, There is also a normally open valve that is piped to a "tell-tale" that will
~
indicate steam leaking past the isolation ~ valve from the emergency condensate header.
Since the condensate and firewater pumps do not produce sufficient head to overcome the steam back-pressure -present in the steam generators under all-postulated conditions, PSC has provided Safe Shutdown Cooling (SSC). procedures to assure cooling water flow through the steam generators.
Procedures SSC-03 (for use after a major fire in a non-congested cable area),
SSC-02 and SSC-04 (for use'after a Steam Line Rupture Detection / Isolation (SLRDIS) actuation caused by ~ a Hi_gh Energy Line Break (HELB), fire, Rapid Depressurization of PCRV Design Basis Accident (DBA-2), or a spurious ictuation),
and SCC-05 (for use after a Design Basis Earthquake or Tornado) all require depressurization of the secondary cooling system before utilizing either the condensate pumps or the firewater pumps to provide cooling water flow through either the emergency condensate header or the emergency feedwater header to the steam generators.
These procedural requirements eliminate the possibility of steam binding for the condensate and firewater pumps.
Steam binding at Fort St. Vrain has been precluded for the feedwater pumps, concensate pumps, and fire water pumps due to their existing
- design, configuration, and procedural requirements.
PSC has maintained and will continue to maintain these design features and i
procedural reautrements as necessary to preclude steam binding from becoming a problem at Fort St. Vrain.
If there are any questions, please contact Mr. M. H. Holmes at (303) 480-6960.
Very truly,yours,s M
R. O. Williams, Jr.
Vice President Nuclear Operations
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ROW /WMD:bre 1
P-88115 Page 4 May 27, 1988 cc:
Regional Administrator, Region IV ATTN:
Mr. T. F. Westerman, Chief Projects Section B Mr. Robert Farrell Senior Resident Inspector Fort St. Vrain
UNITED STATES OF AMERICA NUCLEAR REGULATORY COMMISSIOM In the Matter Public Service Company of Colorado Docket No. 50-267 Fort St. Vrain Unit No. 1 AFFIDAVIT R.
O.
- Williams, Jr., being first duly sworn, deposes and says:
That he is Vice President, Nuclear Operations, of Public Service Company of Colorado, the Licensee herein, that he has read the foregoing information-and knows the contents thereof, and that the statements and matters set forth therein are true and correct f,o the best of his knowledge, information and belief, tu R. O. Williams, Vice President }f, Huclear Operations STATE OF
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COUNTY OF d efuA/
Subscrigd and sworn to before me, a Notary Public on this 41-day of y}')<tep
, 1988.
i ff YdH1 N M ')$U5 ma/W &ulo kawM My ccmmission expires (tu/A 2 13, 198f.
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