ML20028E131
| ML20028E131 | |
| Person / Time | |
|---|---|
| Site: | Beaver Valley |
| Issue date: | 01/14/1983 |
| From: | Carey J DUQUESNE LIGHT CO. |
| To: | Eisenhut D Office of Nuclear Reactor Regulation |
| References | |
| GL-82-32, NUDOCS 8301210015 | |
| Download: ML20028E131 (3) | |
Text
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'At5 Telephone (412) 393-6000 Nuclear Division P.O. Box 4 Shippingport, PA 15077-0004 Janua ry 14, 1983 United States Nuclear Regulatory Commission Division of Licensing Attn: D. G. Eisenhut, Director Washington, DC 20555
Reference:
Beaver Valley Power Station, Unit No. 1 Docket No. 50-334, License No. DPR-66 Generic Letter 82-32 Potential Steam Generator Related Generic Requirements Gentlemen:
Duquesne Light Company welcomes the opportunity to comment on the referenced study. We have limited our comments to four of the twelve proposed actions as it would appear that the remaining actions have a marginal or ineffective value-impact analysis and should there-fore be excluded from future regulatory actions.
Proposed Action la, Secondary Side Inservice Inspection and QA for Loose Parts Comment ,
Based on the fact that two( of the four( } significant tube ruptures to date were caused by loose parts and foreign objects left inside the steam generators following maintenance and inspections, increased inspections may actually increase the probability that a
! foreign object could be unintentionally left in the steam generator j following these types of inspections. The most significant event (Ginna) in terms of leak rate (760 gpm) was caused by a foreign object left in the steam generator. Therefore, license commitments f or an incpection of the secondary side of the steam generator follow-ing naintenance and an active loose parts monitoring program should be all that is required to reduce the probability of this failure mode. These two requirt.ments would have significantly reduced the potential for the Cinna and Prairie Island events.
Proposed Action 2, Inservice Inspection
- a. Full length tube IS1
- b. 48 month ISI I c. Supplemental Sampling
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- d. Denting Monitoring
- e. Unscheduled ISI
- f. Reporting P
15 830114 K 05000334 l PDR
- Beaver Valley Powar Station, Unit No.1 Docket No. 50-334, License No. DPR-66
/* Generic Letter 82-32 Potential Steam I Generator Related Generic Requirements Page 2 and, Proposed Action 3, Improved Eddy Current Testing Techniques Comments These proposed actions are merely geared toward monitoring the roblem and would represent no gain in removing its ef fectsThe source. of the twop(3) severe tube rupture accidents that were apparently
. initiated by corrosion / denting related problems were bound within their FSAR analysis for a tube rupture and the subsequent releases did not exceed the limits of 10 CFR 20. Therefore, industry efforts should only be directed to maintaining a very active secondary water chemistry program and periodic sludge lancing of the secondary side tube sheet interface. Increased inspection of this nature would represent increased personnel exposure and ignore the root cause of corrosion wastage.
Proposed Action (with 6), Secondary Water Chemistry Program combined with Condenser Inservice Inspection Program Comments We agree that maintenance of an active secondary water chemistry program offers the greatest ; aturns in terms of a value impact analysis and enhancement to safety with respect to the tube rupture event. We also agree that a condenser ISI program could be helpfull in maintaining acceptable secondary water quality, but we also believe that the need for such an ISI program is very plant specific and should be lef t entirely j to the discretion of the utility.
r In summarizing, we believe that post maintenance inspections of the l secondary, an active secondary chemistry monitoring program and loose parts monitoring of the steam generator are the only proposed actions that would represent significant gains in reducing the number and severity of tube rupture accidents. There are a number of procedure related enhancements that should be evaluated by utilities to minimize the probability of any f tube rupture initiated release. Among those are:
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qualifying the use of the pressurizer auxiliary spray valve on a limited cycle basis when the spray to coolant l dif ferential temperature exceeds 320F to maximize the l depressurization rate if coolant pumps are tripped.
steaming down the affected generator until coolant pressure
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and secondary side pressure are equalized to avoid water relief through the steam generator safety valves and cool the faulted generator.
- initiating blowdown of the faulted generator to a controlled location to preclude water solid operation and potential secondary safety relief.
., Barver Valley Power Station, Unit No.1 Docket No. 50-334, License No. DPR-66
,- Gectric Letter 82-32 Potential Steam Generator Related Generic Requirements Prge 3 immediate initiation of a cooldown and depressurization upon recognition of a tube rupture safety injection without a boron analysis if all control rods are incarted. This would minimize the delays associated with the cooldown and depres-surization to avoid filling the faulted generator.
provide relief from license requirements whereby the steam to the Turbine Driven Auxiliary Feedwater Pump could be secured remotely if the motor driven feed pumps are operating. This i would minimize the release by way of this flow path since prea-ently only manual isolation of the affected generator is provided procedurally.
permit the use of loop isolation valves to isolate the faulted generator when it has been positively identified.
In consideration of the overall staff concerns with regard to the i safety impacts, protection of the health and safety of the public and exposure to personnel, we believe tnat the items addressed represent the most ef fective blend of actions that need to be taken to minimize the potential risks and probability of a steam tube rupture event.
- References (1) Prairie Island and Ginna Events (NUREG 0651, 0909)
(2) Point Beach 2/26/75 Prairie Island 10/2/79 (3) Point Beach and Surry Unit 2 Very trul yours, 4
J. J. Carey Vice President, Nuclear i
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- Mr. W. M. Troskoski, Resident Inspector U. S. Nuclear Regulatory Commission Beaver Valley Power Station Shippingport, PA 15077 U. S. Nuclear Regulatory Commission c/o Document Management Branch j Washington, DC 20555
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