ML19211A512
| ML19211A512 | |
| Person / Time | |
|---|---|
| Site: | Fort Saint Vrain  |
| Issue date: | 12/10/1979 |
| From: | Varga S Office of Nuclear Reactor Regulation |
| To: | Justin Fuller PUBLIC SERVICE CO. OF COLORADO |
| Shared Package | |
| ML19211A513 | List: |
| References | |
| NUDOCS 7912200048 | |
| Download: ML19211A512 (2) | |
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UNITED STATES g
NUCLEAR REGULATORY COMMISSION g.)
- . j WASHINGTON, D. C. 20555 o, Q
'% *.V /g December 10, 1979
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Docket No.: 50-267 Mr. J. K. Fuller, Vice President Public Service Company of Colorado P. O. Box 840 Denver, Colorado 80201
Dear Mr. Fuller:
The installation of the Region Constraint Devices (Luci Locks) has been discussed in past correspondence (P-79068, 3/23/79; P-79070, 4/6/79) and various meetings (11/1/79,11/20/79). The design of the Luci Locks was proposed as a possible remedy to the FSV Power Fluctuation Phenomenon and they will mechanically interlock fuel regions across the top layer of the core thereby preventing the accumulation of bypass flow gaps at region boundaries. The Luci Locks are expected to stablizie external region gaps at their nominal values and will limit changes in gap flows thereby minimizing pressure differences across regions.
Based on observed data, it has been postulated that changes in gap widths, flows, and pressure distributions contribute to the fluctuation phenomenon in the FSV primary coolant system.
During the previous meetings, NRC staff observed a video-tape of model testing performed on the FSV core using the Luci Locks to prevent fluc-tuations.
Two tests were observed, one was a half scale model, the other a fourteenth scale model.
In both cases region shifts, i.e.,
fluctuations, were observed without Luci Locks in place whereas no fluctuation could be induced even with intentional shaking of the model when the Luci Locks were in place.
NRC consultants at the Los Alamos Scientifi.c Laboratory have analyzed the effect the Luci Locks might have on the dowel shear forces and fuel element impact forces during a seismic event.
The conclusions of the LASL report are that the addition of Luci Locks can be expected to decrease the maximum dowel shear forces; also, for motions produced when fuel block slippage occurs, the fuel element impact velocities and impact forces will be reduced.
I632 04; i0122000 +8
Mr. J. K. Fuller December 10, 1979 The NRC staff has reviewed the effect of the Luci Locks on the fluclear Design, Thermal-Hydraulic Design, Fuel Performance, Structural Performance, and Plant Operations and Testing.
Our evaluations on the above effects on the operation of the plant with Luci Locks in place are presented in the attached Enclosure to this letter.
Based on our review of the potential effects of the Luci Lockr on the core, the proposed operating and test plans, and the test data from cycles 1 and 2, we conclude that the Fort St. Vrain reactor can be safely operated with the installed Luci Locks up to the presently authorized level of 70% of full power.
Should you have any questions or comments please call George Kuzmycz the Project Manager.
Sincerely, C%ma btv ct
/Stev:nA.Varga,ActngAssistantDirector for Light Water Rea tors Division of Project Management
Enclosure:
As stated cc: Bryant O'Donnell, Esq.
Kelly, Stansfield & 0'Donnell 990 Public Service Company Building Denver, Colorado 80201 James B. Graham Manager, Licensing and Regulation East Coast Office General Atomic Company I632 04L 2021 K Street, N.W.
3 Suite 709 Washington, D.C.
20006