ML20031F149
| ML20031F149 | |
| Person / Time | |
|---|---|
| Issue date: | 07/11/1977 |
| From: | Rajan J Office of Nuclear Reactor Regulation |
| To: | Knight J Office of Nuclear Reactor Regulation |
| Shared Package | |
| ML13319A640 | List:
|
| References | |
| FOIA-81-313 NUDOCS 8110190261 | |
| Download: ML20031F149 (5) | |
Text
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NUCLEAR REGULATOllf COMMISSION
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WASWNGTON, D. C. 20555
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s MEMORANDUM FOR:
J. P. Knight, Assistant Director for Engineering, DSS THRU:
R. J. Bosnak, Chief, Mechanical Engineering Branch, DSS FROM:
J. R. N. Rajan, Mechanical Engineering Branch, DSS
SUBJECT:
WESTINGHOUSE MODEI, F STEAM GENERATOR
Reference:
Memo from J. P. Knight to R. J. Bosnak dated June 17, 1977 The referenced memo requested a list of questions relevant to Westinghouse plants proposing to install the Model F steam generator.
This model and Model H are feedring steam generators designed as alternates for incorporation ints. current plant designs and it is claimed that they offer increased conservatism and simplicity while maintaining plant performance. The Model F is designed to be incorporated on 1882, 2785 and 3425 MWt. plants, while the Model H is for the 3800 and 3000 MWt design.
The attached list of questions is applicable to both Models F and H and is based on the limited design information we have available at this time.
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,j ',AT u J. R. N. Rajan Mechanical Engineering Branch Division of Systems Safety a
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S. Pawlicki, SS H. Conrad, SS U. Potapovs. SS L. Shao, OR E(
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H. Brammer, SS MER Members, SS
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MECHANICAL ENGINEl. RING SRANCH DIVISION OF SYSTEMS SAFETY Q... +. --
WESTINGHOUSE H0 DEL F STEAM GENERATOR
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1.
One of the major mechanical modification in the Model F steam generator is the "quartefoil" tube support design.
As a result of this modification and other design changes, the circulation ratio has been increased by a factor of approximately 2.
' Provide a complete vibration analysis of steam generator internals to show that the cross and parallel flow velocities do not produce damaging flow induced vibrations of the tube bundle during ste'ady state conditions as well as operational transients.
Also show that this increased circulation will not result in fretting or wear due to flow induced vibrations at the tube support contact regions.
2.
The size of the tubing in the Model F steam generator has been changed to 11/16 in, dia. and 0.040 in, wall thickness to compensate for the loss of the preheater efficiency.
This thickness is less than both the Model D and Series 51 steam 9enerators tube wall thickness, Show either' analytically or experimentally that the margins of safety available against failure for degraded tubes during normal operation and postulated accident conditions is no less than that available for the two tube sizes used' in the earlier models.
In addition, provide the proposed tube plugging criteria 1
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and the acceptable primary to secondary leakage limits for Technical
.37-Specifications of plants with Model F steam generators. The bases q+-s,.. :
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for determining the minimum tube wall thickness and the margins of safety for degraded steam generitor tubes for normal operating conditions and postulated accident conditions are outi2ned in Regulatory Guide 1.121.
3.
The installation of the Model F steam generator into plants with existing designs will require rerouting of the main feedwater and blowdown line's.
Provide details of the modification of the piping and other interface systems. Also indicate whether or not the Model F steam generator which is a feedring design can be installed in a plant with piping arrangements to accommodate a preheat type steam generator for example the Westinghouse Model E2.
Provide the details of the interface modifications necessary for tuch a change.
4.
Flow induced vibrations originating at the turbine stop valve during operability tests are suspected 'of initiating fatigue cracks in the tubes of a B & W steam generator at the tube supports.
Since the "quartefoil" tube support design of the Model F steam generator is similar to the broached hole type support used in ne once through steam generator, what precautionary measurns are being taken to prevent such an occurrence in Model F steam generator tubes.
5.
Provide the details of the improvements to assure easy access into the tube bundle for inspection, tube removal and sludge lancing.
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