ML20071P643
| ML20071P643 | |
| Person / Time | |
|---|---|
| Site: | Davis Besse  |
| Issue date: | 12/15/1982 |
| From: | Crouse R TOLEDO EDISON CO. |
| To: | Stolz J Office of Nuclear Reactor Regulation |
| References | |
| RTR-NUREG-0737, RTR-NUREG-737, TASK-2.E.1.1, TASK-2.E.1.2, TASK-TM 884, TAC-42964, TAC-44751, NUDOCS 8212270210 | |
| Download: ML20071P643 (3) | |
Text
o HREDO
%s EDISON R o wop.C o n Docket No. 50-346 u, s sm.,
License No. NPF-3
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Serial No. 884 December 15, 1982 Mr. John F. Stolz, Chief Operating Reactors Branch No. 4 Division of Licensing U. 9 Nuclear Regulatory Commission Washington, D.C.
20555
Dear Mr. Stolz:
This is in response to your letter dated Dt. ember 1, 1982 (log No. 1144) relating to Auxiliary Fcedwater System Reliability Evaluation (NUREG-0737 Item II.E.1.1).
Your letter requested a commitment and additional infor-mation relating to Recommendations GS-6 and Additional Short Term Recom-mendation (on redundant condensate storage tank level indication and low level alarms) respectively.
Following is Toledo Edison's response to your letter as relating to the Davis-Besse Nuclear Power Station Unit 1.
Recommendation GS-6 Paragraph 2 of this recommendation requested that you propose Technical Specifications to require a flow test to verify normal flowpath of auxiliary feedwater to the steam generators following an extended shutdown. You did not propose the requested Technical Specification because such a test would require injection of non-deaerated water into the steam generator and that prior to entry into Mode 3, a valve lineup for the AFWS is performed ta veritu valve position.
You further ineicated that, if maintenance has been performed on any AFWS train, a functional test is performed on that train to verify operability.
We agree that the introduction of non-deaerated feedwater to the steam generator can produce adverse effects and, therefore, share your concerns that such injections should be held to a minimum. Since the objective of the test is to assure that system performance has not been degraded during an extended shutdown as a result of maintenance activities, you may proisse an alternative Technical Specification which would require a flow test following:
- 1) a refueling outage or 2) any maintenance or modifications te the auxiliary feedwater system which might degrade system performance or flow path availability.
h
_, THE TOLEDO EDISON COMPANY, EDISON PLAZA 300 MADISON AVENUE TOLEDO. OHIO 43652 7, 9212270210 821215 i
PDR ADOCK O$D00346 i
i
. P.
Dock t No. 50-346 Licanze No. NPF 4 Serial No. 884 December 15, 1982 Page 2 In view of the above discussion, you are requested to:
- 1) concit to propose Technical Specifications in accordance with Recommendation CS-6 in our enclosure to our letter of August 3, 1982, or b) commit to propose the alternate Technical Specification in accordance with the discussion of Recommendation GS-6 as contained in this letter.
Response: We share the NRC's concern that the auxiliary feedwater system (AFWS) functionality be verified following an extended shutdown or following any maintenance on, or modification to this system. Therefore, as indicated in our letter of September 14, 1982 (Serial No. 857) follow-ing a cold shutdown condition and prior to entry into Mode 3, a valve line up for the AFWS is performed for verification of valve positions.
Following maintenance or modifications to this system, a test of the af fected train (s) is performed to verify the functionality of the system.
These tests are done in compliance with the ASME Section X1 code which has been, accepted by the NRC to ensure sjetem degradation has not occurred.
More routine equipment testing on a periodic basis per ASME Section XI further assures system degradation does not occur.
In light of undesired consequences of a loss of steam generator tube integrity, Toledo Edison aims at reducing to minimum, any secondary side perturbations which may challenge this integrity.
The tight controls on secondary side chemistry at Davis-Besse are in conformance with the NRC views relating to the significant impact of these controls on steam generator tube integrity. For details, see Toledo Edison's letter (Serial No. 874) dated December 14, 1982. The tight secondary side chemistry controls at Davis-Besse have precluded any tube failure that may be attributed to this cause. Any unnecessary introduction of the aerated and high iron content water from the proposed auxiliary feedwater flow test will prove to be detrimental to the tight chemistry controls (and steam generator tube integrity) that we have maintained.
Therefore, we are convinced that in view of the test program presently instituted, and the adversity of secondary side chemistry impacts on steam generator tube integrity, the suggested Technical Specification require-ments for a flow test on this system are not warranted.
Additional Short Tera Recommendation - Redundant Level Indication and Low Level Alarms This recommendation would require redundant condensate storage tank level indication and low level alarms in the control room. The purpose of these indications and alarms is to allow the operator to anticipate the aced for make-up water or to transfer to the alternate supply.
The alarm set point should provide at least 20 minutes for operator action.
Your response indicates that you place total reliance upon 'he singic level indicator and alarm coupled with the automatic transfer of suction from the condensate storage tank to the service water backup to protect
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o Dockat No. 50-346 Lictnsa No. NPF-3 Serial No. 884 Lecember 15, 1982 Page 3 the auxiliary feedwater pumps against low level. We do not find this acceptable. During our telephone conference, your staff indicated that other existing systems also may be able to provide information about the level status of the condensate storage tanks, in addition to the tank i
level indicators, and that theee systems may be acceptable to the staff, In view of the above discussion, you are requested to a) commit to instal-f lation in the control room of redundant condensate storage tank level indication and low level alarms, or b) provide suf ficient information to indicate that the operar.or has access to alternate reliable indication of l
condensate storage tank level status to allow at least 20 minutes for j
operator action.
l
[
Response
Each of the two condensate storage tanks (CST) at Davis-Besse has a tank level indicatcr in the contrcl room.
In addition, separate I
level switches are provided to facilitate an annunciator alarm in the i
cratrol room indicating high/ low level in the CST. See Figure 10-5 of the Davis-Besse FSAR for details. The low level alarm is set at approximately*
r 38'.
This corresponds to approximately 200,000 gallons of condensate water that is available for auxiliary feedwater pumps. Based on the maximum flow conditions, with both auxiliary feedwater pumpa taking suction from one CST, this allows a time period of the order of more than an hour before the water level reaches the CST discharge piping. Further, since there is approximately 18 feet of static head between the bottom of the CST and the suction of the sur'liary fee? water pump, the pump suction pipe will be filled with water even if the water level in the CST was at the lowest point. As noted in our September 14, 1982 letter, this will ensura availability of adequate net positive suction head and subsequent preclusion of any damage to the pumps. Based on the above, it is concluded that the low level alarm provides adequate early warning in the controi room to anticipate the need for make up water or to transfer to the alternate water supply as needed.
In any event as indicated in our September 14, 1982 letter, the automatic transfer of suction to the service water system will ensure that no damage is incurred to the auxiliary feedwater pumps.
Very truly yours, lff n'
J RPC:SCJ:lah q
i cc: DB-1 NRC Resident Inspector i
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