ML20082H448
| ML20082H448 | |
| Person / Time | |
|---|---|
| Site: | Crane  |
| Issue date: | 11/23/1983 |
| From: | Hukill H GENERAL PUBLIC UTILITIES CORP. |
| To: | Stolz J Office of Nuclear Reactor Regulation |
| References | |
| RTR-NUREG-0737, RTR-NUREG-737 5211-83-346, NUDOCS 8312010159 | |
| Download: ML20082H448 (2) | |
Text
.a Nuclear Ismiag rete""
Route 441 South Middletown, Pennsylvania 17057-0191 717 944 7621 TELEX 84 2386 Writer's Direct Dial Number:
November 23, 1983 5211-83-346 Office of Nuclear Reactor Regulation Attn:
J. F. Stolz, Chief Operating Reactors Branch No. 4 Division of Licensing U. S. Nuclear Regulatory Commission Washington, D.C.
20555
Dear Sir:
Three Mile Island Nuclear Station, Unit 1 (TMI-1)
Operating License No. DPR-50 Docket No. 50-289 EFW Flow Devices (D/P) Testing In our submittal of August 25, 1983 (5211-83-231), GPUN described the differ-ential pressure (d/p) flow measuring system using annubtrs for the Emergency Feedwater System.
In item III,F of the enclosure to that letter, we indicated that "the flow instrumentation are reliable and accurate and are designed to monitor the full range of system flow requirements". Recent tests performed on the EFW system in conjunction with OTSG testing indicated oscillations at low flow conditions (less than approximately 100 gpm) outside the + 10% criteria.
CPUN's preliminary evaluation concludes that cavitation on the outlet of the feedwater flow control valve during low flow conditions caused the oscillations.
Tests indicate that at high flow conditions (above 400 gpm) the d/p flow instru-ments are within + 10%.
We have concluded that the oscillations at low flows do not affect the functional capability of the EFW system or the ability of the operator to take proper action and are, therefore, acceptable for the following reasons:
a.
Emergency feedwater flow is initiated automatically on loss of all RCS pumps or both feedwater pumps.
Should initiation occur, tl'e accuracy of the instrument would be within allowable limits for high flows to confirm that EFW flow is sufficient.
For low flow conditions the flow instrument confirms the proper initiation of EFW (i.e. flow is occuring).
Accuracy of flow rate is not necessary at low flows.
In addition, EFW flow would be automatically controlled by the ICS on steam generator level, not EFW flow rate. Based on this, the EFW flow devices will provide indication to the operator that the system is functioning.
8312010159 831123 PDR ADOCK 05000289 g ()() l A
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b.
During manual takeover of the emergency feedwater system, the operator does not control feed flow based on this flow indicating instrument i
alone. Emergency'Feedwater continues to be controlled based on OTSG level and pressure (level to prevent over/under-filling and pressure to prevent over-cooling). The operator's attention is focused on these instruments when regulating flow. The emergency feedwater flow indication provides only one positive means of verifying that flow is being delivered to the steam generators; it is not relied upon to regulate flow.
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This clarification describes the EFW d/p flow system as currently installed and tested. Therefore, GPUN concludes that the EFW flow indicating system is acceptable and meets the requirements of NUREG 0737 and our commitment reflected in the Partial Initial Decision of December 14, 1981. However, during the Power Esca-lation testing data will be collected and used to assist the operators in under-standing how the EFW flow devices are expected to perform under various EFW flow conditions.
Sincerely, H. D. lu ill I
Director of TMI-l i
HDH:LWH:vj f:j rg cc:
J. Van Vliet R. Conte
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