ML19305C081
| ML19305C081 | |
| Person / Time | |
|---|---|
| Site: | Crane  |
| Issue date: | 03/19/1980 |
| From: | Herbein J METROPOLITAN EDISON CO. |
| To: | Reid R Office of Nuclear Reactor Regulation |
| References | |
| TLL-115, NUDOCS 8003250563 | |
| Download: ML19305C081 (2) | |
Text
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I Metropolitan Edison Company Post Office Box 480 a
g Middletown, Pennsylvania 17057 717 9444041 Wnter's Direct Dial Number March 19, 1980 TLL 115 Director of Nuclear Reactor Regulation Attn:
R. W. Reid, Chief Operating Reactors Branch No. 4 U. S. Nuclear Regulatory Commission Washington, D.C.
20555
Dear Sir:
Three Mile Island Nuclear Station, Unit I (TMI-1)
Operating License No. DPR-50 Docket No. 50-289 Valve Lineup Procedural Changes This letter is in response to your letter of January 22, 1980 concerning a request for information on the effects of valve lineup procedural changes.
Your letter indicated a concern for a LOCA outside containment due to the overpressurization of the low pressure injection piping and the need to test the check valves during startup and operation with the motor operated valve open.
Background
TMI-I's low pressure injection piping from the reactor vessel to the motor operated valve (DH-V 4 A/B) is high pressure piping designed for 2500 psig and 300 F.
The low pressure piping from DH-V 4 A/B to the decay heat pump suc ion isolation valves is designed to 470 psig at 3000F. The three pressure barriers are two check valves (CF-V 5 A/B and DH-V 22 A/B) in series with the closed DH-V 4 A/B.
Question What is the adverse safety impact of starting / operating with the MOV in the open position?
Response
If the DH-V 4 A/B were lef t open, this would eliminate one of the three redundant pressure barriers. FSAR Table 5-4 and Figure 5-35 take credit for one check valve and the closed MOV. Obviously, reducing the number of pressure barriers would reduce the number of f ailures L2cessary
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to allow overpressurization of the low pressure piping to occur.
This increases the probability of overpressurizing the low pressure portions g
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of the Decay Heat System. Overpressurizing the Decay Heat System could cause a loss of reactor coolant accident and/or a loss of Decay Heat l
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System redundancy. This increased probability would exist for both startup and normal plant operation.
1 Sincerely, c
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J. G. Herbein Vice President Nuclear Operations JGil:DCM: hah i
cc:
J. T. Collins J
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