ML20010B559
| ML20010B559 | |
| Person / Time | |
|---|---|
| Site: | Fort Saint Vrain  |
| Issue date: | 02/05/1981 |
| From: | Swart F PUBLIC SERVICE CO. OF COLORADO |
| To: | John Miller Office of Nuclear Reactor Regulation |
| Shared Package | |
| ML19263D739 | List: |
| References | |
| FOIA-81-127 NUDOCS 8108170235 | |
| Download: ML20010B559 (2) | |
Text
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puMe Service Company Of O h s b y
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12015 East 4Gth Avenue, Ssite 440i' Denver, C0 30Z39 February 5, 1981 Fort St. Vrain.
s Unit No. 1 i
Mr. James R. Miller, Director i
Special Projects Branch U.S. Nuclear Regulatory Commission Washington, D.C.
20555 Docket No. 50-627
Subject:
Submittal of Draft Reports for February 10, 1981 Meeting
Dear Mr. Miller:
l-Our letter of December'4, 1979 (P-79293) described fluctuation testing to be performed below 70% power after installation of the' region con-straint devices (RCDs).
In our letter of May 27,'1980 (P-80118), it was.
indicated that all tests outlined in P-79293 had been completed with the~
exception of the actual fluctuation tests specified by RT-500H.
It was also indicated that the installation of the RCDs had no significant in-pact on the normal operating characteristics of the core.
In accordance with the schedule agreed upon during the January 27, 1981 meeting of the Advisory Committee on Reactor Safeguards Subcommittee 'on j
i Fort St. Vrain, Public Service Company is submitting ten (10) copies of the draft report, " Testing at Fort St. Vrain After Installation ofsRegion' j
Constraint Devices." This report summarizes the results Df the RT-500H
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tests performed in-November and December 1980, in which attempts were made to induce fluctuations.
As described in the report and at the ACRS meeting, twenty-one attempts
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l were made to induce fluctuations under reactor conditions which were known to be unstable prior to BCD installation.
No fluctuations were obtained.
However, during'the transition between %55% and %59% power, a single re-distribution of region outlet temperatures was observed.
This redistri-bution has been shown to be repeatable.
The data collected during testing
.ad further analyses indicate that the redistribution is the result of c
. very small displacements of fuel and reflector elements.
An evaluation of
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the data indicates that the consequences of the temperature redistribution are acceptable and bounded by those described in the August 11, 1980 fluctuation safety evaluation (P-78127).
Plans for testing above 70%
power (RT-500J) are also described in the report.
0108170235 810529 '
= ' e; y To:
James R. Miller, Director Page 2.
Amendment 22 to the Fort St. Vrain Facility Operating License required Public Service Company to perform the following prior to operating the reactor above 70% power:
" Provide for staff review and approval a minimum of one additional RECA3 code verification analysis of plant transient response. The transient response used for verification must be performed subsequent to corrective actions taken to eliminate the core fluctuations.
Alternatively, an acceptable power level should be proposed which is based on accident analyses which account for-this prediction uncertainty."
In accordance with the sched'ule agreed upon during the January 27, 1981 meeting of the Advisory Committee on Reactor Safeguards Subcommittee on Fort St. Vrain, PSC is submitting ten (10) copies of the report, "RECA3 Code Verification Analysis with Region Constraint Devices Installed."
The results of this analysis indicate that by providing as input to RECA3 radial power distributions calculated using FSAR methods, the i
anomalous behavior previously noted in certain refueling regions is resolved.
With this resolution of previously noted anomalies, the con-servative accident analysis evaluated by the staf f in imendment 22 Safety Evaluation P.eport remains bounding.
We look forward to discussing the contents of these draft reports with the staff during our February 10 meeting in Bethesda.
PSC requests completion of your review to facilitate a release to operate Fort St., Vrain above 70%
power by March 5, 1981, as discussed during the ACRS meeting.
This schedule will allow approximately one month for continuation of startup testing, SUT B-0, and RT-500 testing prior to the refueling outage, which is scheduled to begin on April 3, 1981.
Very truly yourg, f
4 I
J2t Uy W
Frederic E. Swart Nuclear Project Manager b
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