ML20062C991
| ML20062C991 | |
| Person / Time | |
|---|---|
| Site: | Fort Saint Vrain  |
| Issue date: | 11/09/1978 |
| From: | Warembourg D PUBLIC SERVICE CO. OF COLORADO |
| To: | Kuzmycz G Office of Nuclear Reactor Regulation |
| References | |
| P-78183, NUDOCS 7811160071 | |
| Download: ML20062C991 (4) | |
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pu1311e service company oe cewedo P. O. Box 361, Platteville, CO 80651 November 9, 1978 Fort St. Vrain Unit No. 1 P-78183 Mr. George Kuzmycz Project Manager,
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Div. of Project Management-Special Projects U. S. Nuclear Regulatory Commission b
Washington, DC 20555 Docket No. 50-267
Subject:
Fort St. Vrain Operations Oscillation Testing
Dear Mr. Kuzmycz:
Pursuant to our telecon of November 6, 1978, this letter shall serve as a preliminary report under the provisions of your letter dated September 26, 1978, concerning testing in the fluctuating mode and the reporting require-ments of Item 8 of this same letter.
On November 4, 1978, we were in the testing mode under the auspices of RT-500A in an attempt to test for fluctuations at or near 40% power. During
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this test one of the limits ( 30*F) for the steam generator module main steam temperature) was exceeded. The sequence of events and conditions leading to exceeding this limit are summarized in the attachment.
It should be noted that this information is preliminary at this point in time, and that the detailed data is presently being reduced to allow further analyses. It is anticipated that the data will be reduced by the end of the week and analysis will begin as soon as possible. We should be in a position to discuss this event along with our future plans prior to November 17, 1978.
In the interim the reactor has been returned to normal operation, and, in accordance with your letter of September 26, 1978, no further testing will be done without your express approval.
Very truly yours, Ww Don Warembourg Manager, Nuclear Production y
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SEQUENCE OF EVENTS FLUCTUATION TESTING 11-04-78 TORT ST. VRAIN NUCLEAR GENERATING STATION t
Time E-ent/ Conditions 0015 Test conditions were established for fluctuation testing Plant condi'tions: All control systems in automatic Reactor power 39.8%
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Core resistance 65 Core AP 2.17 psi He Flow 52.1%
Core Outlet Temperature 1185'F 0055 Commenced power increase from 39% to 43% at 0.5%/ min.
0145 All conditions stable at 43%. No fluctuations evident.
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Plant conditions: Reactor Power 43%
Core resistance 65 Core AP 2.43 He flow 55.6%
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Core outlet temperature 1199'F 0340 Commenced power increase from 43% to 49% at 0.5%/ min.
Shim rods (3B) were pulled during the load increase to limit reg-rod withdrawal.
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Sequence of Events (continued)
Page 2 Time Event / Conditions 0400 Fluctuations were initiated. Although the specific data is still in the process of being reduced, the fluctuations,-in general, were characterized by swings of about 1.5% on Channel VII with Channel VI being relatively stable (less than 1%). Main steam temper-atures were fluctuating between 20*F.
0430 Approximately 30 to 35 minutes into the fluctuation, the main steam temperature for steam generator modale
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B-1-1 dropped 120*F.
Some temperature drop was also evident on other steam generator modules, particularly B-1-4 and B-2-2.
(From the recorder tracer it is difficult to quantify the temperature drops in B-1-4 and B-2-2, but it appears that these two modules experienced a temperature drop in excess of 50*F).
With the observation of the main steam temperature swings immediate steps are taken to reduce reactor power to terminate the fluctuation.
Plant conditions at 49%: Core resistance 65 Core A,p 2.85 0445 Reactor power reduced to 43%. Fluctuations continue, l
(It should be noted that only one drop in main steam temperature was observed and that temperature recovered immediately after the drop). Reactor power reduction from 43% to 35% commenced to terminate the fluctuation.
l 0515 Reactor power reduced to 35%. Fluctuations continue
-for a short period of time. Main steam temperatures are within 20*F.
0540 Fluctuations dampened out.
All conditions stable.
Plant conditions: Reactor Power 35%
Core AP 1.84 He Flow 49.7%
Lore Outlet Temperature 1140*F
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Sequence of. Events (continued)
Page 3 Time Event / Conditions 0630 Reactor power increased to 40%
0700 Fluctuation,s (but of a much smaller magnitude) are
. observed again. Possibly the fluctuations are a continuation of the previous fluctuations. Main steam temperatures are within 15'F variation in
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the fluctuation.
Plant conditions: Reactor power 40%
Core AP 2.2 psi 0745 Reactor power reduced to 35%
4 0815 Fluctuations stopped No further testing in the fluctuating mode has or will be done pending review with NRC staff.
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