ML20004D441
| ML20004D441 | |
| Person / Time | |
|---|---|
| Site: | Crane  |
| Issue date: | 06/05/1981 |
| From: | Hukill H METROPOLITAN EDISON CO. |
| To: | Stolz J Office of Nuclear Reactor Regulation |
| References | |
| L1L-176, NUDOCS 8106090400 | |
| Download: ML20004D441 (3) | |
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Metropolitan Edison Company NII Post Office Box 480 Middletown, Pennsylvania 17057 Writer's Direct Dial Number June 5,1981 LlL 176 Office of Nuclear Reactor Regulation Aten: John F. Stolz, Chief Operating Reactors Branch No. 4 U. S. Nuclear Regulatory Commin.on Washington, D.C.
20555
Dear Sir:
Three Mile Island Nuclear Station, Unit 1 (TMI-1)
Operating License No. DPR-50 Docket No. 50-289 Environmental Qualification Questions The attached questions and answers confirm conversations between our respective staff's over the past week regarding clarification of our submittal of May 18, 1981 (LlL 161).
Sincerely, H. D.
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Attachment L1L 176 Ql. For the isolation valve identified by Note 1, what are the effects after submergence?
A1.
There is no affect on the contactors which energize the actuator motor.
Since the contactors are located in the MCC and are not submerged they will not cause a change in valve position.
If the limit switches on the actuator are shorted by submergence the control circuit fuse should blow. This would result in a loss of valve position indicator light. This would not be a problem because the valve position is verified by the operator long before the loss of the light occurs.
The submergence of any of the electrical components in these motor operators will not affect any other electrical system because of the isolation provided by the MCC.
Q2. What is the basis for the qualification of the motor brakes in Note 3?
A2.
By analysis of the materials in the motor brake that are affected by radiation. The SB LOCA could occur af ter 20 years of full power operation, and still have the brake operate satisfactorily.
Q3. At what level are the relocated SG level transmitters referred to in Note 47 A3.
The bottom of the transmitters are 5'9 3/4" or more above the reactor.
building floor.
Q4. Are the cables supplying the SG level transmitters subject to submergence?
A4.
No.
They feed from above.
Q5. What is the basis for the qualification of the Conax connectors referred to in Note 57 AS.
These connectors use the same materia.~.s as those in Note 6, therefore tney are qualified to the same enviro 1ments.
Q6. Will the Conax connectors in Note 6 be used to replace those in Vol. IA, Common, Sheets 10 and 11 of the 79-01B Submittal? If so, when will they be installed?
A6.
Yes. These are the replacement connectors and they will be installed prior to restart.
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Q7. To what radiation level is the Limitorque operator for NS 't-35 qualified?
7 A7.
A minimum of 2 x 10 rads total integrated dose.
Q8. How was the flood level in the reactor building decreased from 5.94 ft. to 5.66 ft.?
A8.
By using a more realistic, but still conservative model of the steam generator exterior configuration.
Q9. What dose rate was used in the reactor building to determine the normal integrated dose? How was it obtained?
A9.
The dose rate used was 100mR/hr.
It was obtained by actual plant measurements taken over a 41/2 year period.
Q10. What is the dose rate on the Decay Heat Removal Pump for SB LOCA conditions?
A10.
An approximation of the dose was determined by comparing the source terms calculated in accordance with NUREG 0737 Item II.B.2, and representative source terms available in the GAISSAR Chapter 12.
This comparison yielded a 104 difference. The corresponding NUREG 4
0737 dose rate calculated was reduced by the same factor of 10 for the initial post-accident rate.
The resultant initial dose rate was 4 Rad /hr to the pumps. This rate would then decay over the next 180 days in the same fashion as the NUREG 0737 cource. At the end of 180 days the dose rate would be 4 mR/hr.
5 Qll. What would be the effect cf a beta dose of 2.2 x 10 rads on equipment inside containment?
All.
No effect. The electrical equipment required to bring the plant to a safe shutdown is in conduit or metal enclosures.
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