ML19220C320
| ML19220C320 | |
| Person / Time | |
|---|---|
| Site: | Crane  |
| Issue date: | 01/23/1978 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML19220C319 | List: |
| References | |
| SER-780123, NUDOCS 7904300375 | |
| Download: ML19220C320 (4) | |
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i Three Mile Island Unit No. 2 Review of the Proposed Modifications of IMI Unit 2 Stean Generator Instrumentation Program Safety Evaluation Repor:
Mechanical Engineering 3 ranch Division of Systems Safety Introduction By let:er dated Dec. 22, Metropolitan Edison Company has submitted a proposed Steas Generator Instrumentation Program. The purpose of the =easure=ent program to be condue:ed on the "3" CTSG at TMI-2 is to provide tube response, flow data and plant process data.
These data are to be used to evaluate uhe effect of nor:21 and transient plant operation on the response of tubes in the OTSG and relate the response of the tubes to the most plausible steam flow excitation rechanism.
It is proposed to acquire the following data during the test program.
Response measurements of on-lane tubes and of f-lane tubes at the upper two spans and between the ninth and tenth support plates during normal operating and transient conditions.
. Measurements of steam pressure and flow during transients such as turbine stop valve testing for correlacion with tube response.
The measurer'.nt programs at Oconee Nuclear Station Units #1 and 2 were sisii r to the proposed program at TMI-2.
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Discussion A modification of TMI Unit 2 OTSG "3" is necessary to accommodate the instrumentation. The detailed strest calculations in ".he reports (References 1 through 7) were performed by the applicant to demonstrate that the structural integrity of individual components as well as the total OTSG in its final configuration will be equivalent to that described in the FSAR.
The stress report for the instrunentation progra (ref. 2) contains the sicing calculations for the primary handhole, the modified 5 in. mecondary handhole and the primary manway to support the steam generato-instrumentation progra=.
Also included in this report are calculations wht:n show that a material change from SA-540, 3-23 Class 5 to SA-540 3-23 Class 4 for handhole and manway bolts will have no significant effect on the design stress levels.
The stress levels in the primary handhole, secondary handhole and the primary canway (including bolts) have been shown to be within ASME C de Section III allowable limits.
The OTSG enclosure analysis (ref. 4) verifies the structural adequacy of the enclosure cans for routing accelerometers cables through the OTSG head at the inspection and manway openings.
Stress resulting from flow icads, and ther=al stresses are considered and a fatigue analysis has been performed. The enclosure cans have been found to be structurally adequate. The alicwable bolt torques for the studs through the cans have been found to be greater than those required for both initial and subsequent torque-ups.
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. An analysis to verify the struer. ural adequacy of the internal instrumenation routing has been performed. The conponents which carry the =ain structural loads are investigated, bushing, lockings, caps, and other co:ponents not highly stressed are not addressed. The routing has been found adequate for one fuel cycle (2 yrs.) subject to the following conditions:
1.
The pipes should not be fittel tightly into the elbows.
2.
The bolt torque should not exceed a.
Yoke: 125 ft-lbf b.
Elbow: 15 f:-lbf c.
Wall bracket: 15 ft-lbf (full weld) 11 ft-lbf (3/4 in weld) 3.
The pipe cover should have 1 1/4 inches of welds between supports.
Evaluation The.NRC staf f has reviewed the information sub=itted by the licensee to show compliance with the equipnent specification, and our evaluation is as follows:
1.
Infornation provided by the appl;; ant provides sufficien: assurance that neither the structural integrity nor the operational characteristics of any safety related equipment is effected by the proposed =odifications.
2.
Additional structures will not fail as a result of these odifications and the consequences of an accident will not be increased by this mechanism.
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The instru=entation programs at Oconee 1 and 2 are very similar to the one proposed at IMI-2.
The operating experience ac Oconee plants provides additional aesurance that there is no reduction in the safety margins as defined in the TMI-2 FSAR and technical specifications.
Based on the above evaluation the staff finds that the proposed modifications do not pose any danger to the health and safety of the public and are accept-able.
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