ML20058N442
| ML20058N442 | |
| Person / Time | |
|---|---|
| Site: | LaSalle  |
| Issue date: | 12/17/1993 |
| From: | Vonk M COMMONWEALTH EDISON CO. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM), Office of Nuclear Reactor Regulation |
| References | |
| IEB-93-002, IEB-93-2, NUDOCS 9312220002 | |
| Download: ML20058N442 (3) | |
Text
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[~,, ) Commonw cith Edison
(
1400 Opus Place Downers Grove, Ilkno:s 60515 December 17, 1993 l
Office of Nuclear Reactor Regulation U.S.
Nuclear Regulatory Commission Washington, DC 20555 Attention:
Document Control Desk l
Subject:
LaSalle County Nuclear Power Station Units 1 and 2 l
Supplemental Response to NRC Bulletin 93-02,
" Debris Plugging of Emergency Core Cooling Suction Strainers" NRC Dockets 50-373 and 50-374
References:
1)
D.
J. Chrzanowski letter to Document Control Desk dated June 9, 1993 l
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2)
URC Bulletin 93-02:
" Debris Plugging of l
Emergency Core Cooling Suction Strainers" l
The purpose of this letter is to provide supplemental information to our response (Ref. (1)) to NRC Bulletin 93-02 l
(Pef. (2)) and to document the actions agreed upon during a conference call between NRR and LaSalle station on December 9, 1993.
This call involved CECO response to questions _aised by the NRR staff during review of the reference (1) to the subject bulletin.
Specifically, NRR e:: pressed concern that t e LaSalle decision to leave certain original equipment (permane 'ly installed) polyester ventilation filters inside the pr mary containment was not an adequate implementation of the Bulletin requirements.
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CECO indicated that the site review did not consider the original filters to be applicable to the Bulletin, and that they l
were not originally considered to be fibrous.
Subsequent review l
of the filter construction indicated that the resin binder in the filters would break down after some time above 300 F and the filters could then break up into transportable fibers.
This review was initiated as a response to NRR's questions about the LaSalle response to the bulletin, which noted that the polyester i
filters were present in the drywell cooler air handling units.
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9312220002 931217 i
PDR ADOCK 05000373 h
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PDR h
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I Do'cument Control Desk December 17, 1993 CECO also stated that the preliminary review of possible effects of filter removal on the drywell coolers indicated that 1
operational problems or cooler fouling were not likely, and that LaSalle would remove the filters from the Unit 2 ventilation I
coolers prior to startup from the current refuel outage.
Discussions with the System Engineer for primary containment ventilation and maintenance personnel indicated that the filters are not normally found with significant accumulation of materials r
when they are replaced each refueling outage.
The change will require periodic (refuel interval) cleaning, and flow / dP l
verification.
CECO stated that the initial response of removing l
the filters from Unit 2 was being done as an interim measure, and that a final decision would be made for the next Refuel outage on Unit 1, scheduled for March 1994.
There was additional discussion of the initial CECO l
evaluation of the potential for filter material to plug the ECCS pump suction strainers.
CECO had performed some tests of the filter material, including:
1)
Oven heating at 360 F for 15 min, 1 hr, and 20 hours2.314815e-4 days <br />0.00556 hours <br />3.306878e-5 weeks <br />7.61e-6 months <br /> 2)
Boiling and exposure to steam for 90 minutes.
j e
The filter material did not degrade for case 1.
The boiled sample appeared to weaken somewhat but did not break down, and steam exposure did not appear to significantly affect the sample.
The samples were given the NRC personnel.
The CECO conclusions from the evaluation were that the filter material was not specifically qualified for the LOCA environment, and that for
[
this reason, did not meet the requirements of the Bulletin, and l
l would be removed.
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l Because the ambient heating condition did not appear to l
degrade the material, the physical concerns for the material appear to be limited to direct steam impingement on a filter, and i
as such the total inventory of filter material is less of a l
consideration than the quantity at a single location (i.e. only 1 line break is expected for analyzed accidents).
The possible pathways for filter sections or disassociated fibers to reach the ECCS strainers were discussed, as well as~the LaSalle ECCS strainer design, each of which have a large number of slots that are.050 inches tall by ~ 8 inches long.
These strainers have less potential for fouling than strainers which have holes on the outside surface.
CECO committed to document an evaluation of the ECCS impact for Unit 1, which is at power.
This issue is not considered an operability concern for Unit 1, but is being handled as part of the submittal and acceptance of the CECO response to NRC Bulletin 93-02.
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ACTION C0!EITMENTS:
DATE DUE:
STATUS:
Ceco provide letter summary of 12/17/93 DONE discussion and committed actions 12/17/93 Ceco remove polyester filters from 12/20/93 DONE Unit 2 containment prior to startup 12/16/93 from L2R05.
Ceco document evaluation of the 12/20/93 ON presence of filters for accident SCHEDULE conditions, for Unit 1.
CECO co'r,0..ete evaluation of long term Prior to solution (filter removal, substitute, Shutdown 1 or analyze / accept present design) for LlR06 CECO submit amended Bulletin response Within 30 to NRC.
days following completion of the above evaluation If Unit 1 is required to go to Cold Shutdown prior to L1R06, polyestor filters will be removed prior to startup.
To the best of my knowledge and belief, the statements contained in this document are t rue and correct.
In some respectc these statements are r<*
based on my personal knowledge, l
but on "nformation furnished b; ther Ceco employees, contractor l
employees, and/or consultants.
~:h information has been re>iewed in accordance with comp-
/ practice, and I believe it to be rel:able.
If there are any questions or comments, please contact me at t708) 663-7292.
p:::::::::: -- ::::f Sincerely, b
.,y,h o d 'b.
James h
S y
s mm hAENc cccccc/o Martin J. Vonk 3%i //% '
Generic Issues Administrator b
Nuclear Regulatory Services cc:
J. Martin, Regional Administrator, NRC Region III J.
Dyer, Director of Directorate III-2, NRR A.
- Gody, Jr.,
LaSa]le Project Manager, NRR D.
Hills, LaSalle Senior Resident Inspector l
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