ML19289D794
| ML19289D794 | |
| Person / Time | |
|---|---|
| Site: | LaSalle  |
| Issue date: | 03/07/1979 |
| From: | Delgeorge L COMMONWEALTH EDISON CO. |
| To: | Parr O Office of Nuclear Reactor Regulation |
| References | |
| NUDOCS 7903140457 | |
| Download: ML19289D794 (4) | |
Text
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s.
Commonwealth Edison One First National Plaza. Chicago. Illinois Address Reply to: Post Office Box 767 Chicago, Illinois 60690 March 7, 1979 Mr. O.
D.
Parr, Chief Light Water Reactors - Branch 5 Division of Project Management U.S. Nuclear Regulatory Commission Washington, D.C.
20555
Subject:
LaSalle County Station Units 1 and 2 Safety Evaluation Report - Open Items NRC Docket Nos. 50-373 and 50-374 References (a) :
O.
D.
Parr letter to L.
O.
DelGeorge dated October 16, 1978 (b) :
O.
D.
Parr letter to L.
O.
DelGeorge dated December 21, 1978 (c) :
O.
D.
Parr letter to L. O. DelGeorge dated January 22, 1979 (d) :
O.
D.
Parr letter to L.
O.
DelGeorge dated February 5, 1979
Dear Mr. Parr:
As you know, Commonwealth Edison is committed to respond to the LaSalle County safety evaluation report open items identified in References (a), (b), (c) and (d) by March 23, 1979.
The status of each of these items was reviewed with you and Mr. A. Bournia on February 28, 1979.
At that time, it was indicated that Canmonwealth Edison is prepared to make commitments to resolve certain of those open items.
It is the purpose of this transmittal to address six items and to document this applicant 's commitment with respect to each.
I.
With respect to Item 6 in Reference (a), which addresses the diesel engine air start system:
The NRC's Standard Review Plan 9.5.6, Rev. 1, post-dates the period during which the LaSalle County diesel engine air-start systems were designed.
These standards indicate the acceptability of an air-start system capable of five successful starts on each redundant pair of starters per diesel engine.
h/20 790314N/5~7 6
Commonwealth Edison NRC Docket Nos. 50-373/374 Mr. O.
D.
Parr: March 7, 1979 Commonwealth Edison required only three starts per redundant pair of starters.
It is worth noting at this point that the Safety Evaluation Report for Zimmer Station ($ 9.6.1) concludes that such a three-start system is acceptable.
Qualification tests performed by General Electric at Stewart-Stevenson (the vendor for the GE diesels being used at LaSalle County) demonstrated the capability of the present design to provide a minimum of six cold starts.
Furthermore, it is judged, based on those vendor tests, that the LaSalle diesel air-start system is capable of five starts on each redundant pair of starters which have separate air accumulators.
During the prototype qualification testing of the LaSalle County HPCS diesel engine start system (which is identical to the start system on all LaSalle diesels), successive starts per redundant starter pair will be demonstrated confirming the capability of the system to meet SRP 9.5.6.
General Electric's test program documented for this qualification test, NEDO-10905, has recently been augmented in response to NRC questions via NEDO-10905-1 and in-cludes a reference to the five start demonstration test.
Commonwealth Edison shall provide a letter report with preliminary test results indicating the tested capability of the LaSalle diesel air-start system.
Demonstration of a five start capability during this test will confirm the applicant's position that the air-start system, as currently designed, is adequate and satisfies the current SRP.
In the event a five start capability per redundant starter is not demonstrated, an additional accumulator tank will be added to each air starter half train.
II.
With respect to Item 2 in Reference (c), which addressed the use of the GEXL correlation for LaSalle Unit 1 fuel cycle 2:
General Electric has submitted the licensing topical report " Basis for 8x8 Retrofit Fuel Thermal Analysis Application,"
NEDE-24131 and is currently engaged in on-going discussions with the NRC Staff relative to the GEXL correlation and recent boiling transition data.
General Electric is currently reviewing questions from the Staff on that report.
.s.
Commonwealth Edison NRC Docket Nos. 50-373/374 Mr. O. D.
Parr: March 7, 1979 Commonwealth Edison commits to incorporate the latest approved form of the GEXL correlation at the time of reload for the LaSalle County units.
This reload analysis will rely on the latest boiling transition data available for 8x8 fuel bundles with two water rods and shall reflect agreements reached between General Electric and the NRC Staff relative to resolution of comments on NEDE-24131.
III.
With respect to Item 3 in Reference (c), which addresses hydrodynamic stability analyses:
Commonwealth Edison commits to provide as a part of future reload analyses updated hydrodynamic stability analyses.
The hydrodynamic stability calculations, of necessity, reflect the core stability condition that exists at the time the analysis is performed.
Therefore, these analyses will be provided as a part of the reload submittal.
IV.
With respect to Item 10 in Reference (c), which addresses low pressure containment leakage testing:
The position of Commonwealth Edison relative to the necessity for containment leak testing of the type identified in this item has been clearly stated and comprehensively justified in response to FSAR Question 21.53.
Because the LaSalle County containment design incorporates a stainless steel liner in the suppression chamber ceiling on the underside of the drywell floor, a leak-tight barrier between the drywell and wetwell exists.
Since all penetrations through the drywell floor are welded, no leakage through the drywell floor is expected.
Therefore, although low pressure testing of the sort proposed by the NRC might be reasonable for unlined containments, it is unwarranted at LaSalle.
However, in order to facilitate the review process and give the NRC an objective basis upon which to independently con-clude that the LaSalle containment bypass leakage position is justified, Commonwealth Edison commits to perform the low pressure containment leak tests described in FSAR Q21.53.l(b) and (c).
This test will be performed prior to initial operation and again at the first refueling outage prior to the second fuel cycle.
Satisfactory completion of these tests will verify the applicant's judgement that the drywell floor is leak tight.
The performance of such a test at each refueling outage has the potential of adding one critical
Commonwealth Edison IEC Docket Nos. 50-373/374 Mr. O.
D.
Parr: May 7, 1979 path day to every refueling with the attendant costs of replacement power.
Such a financial penalty is unjustified because the LaSalle liner design precludes the occurrence of leakage of the type which such tests are intended to detect.
V.
With respect to Item 12 in Reference (c), which addresses the confirmation of containment draw-down capability:
Commonwealth Edison commits to perform a leak test of the secondary containment to confirm assumptions relative to inleakage and time required to reestablish containment design pressure (-0.25 inches of water gauge).
This test will be performed prior to operation of the LaSalle County units.
VI.
With respect to Item 7 in Reference (d), which addresses anticipated transients without scram:
Commonwealth Edison is aware of the recent Commission activities related to ATWS including NUREG-0460, Supplement 3.
Commonwealth Edison shall implement a recirculation pump trip for ATWS as discussed in NUREG-0460, Supplement 3, S 2.3, Table 1, Note 1 It is acknowledged that there is the potential for other plant modifications on the LaSalle County units in the event an ATWS rule or other related NRC action is adopted.
It is judged that the cammitments identified in this transmittal provide the basis for closing :he open items to which each commitment refers.
Should you have any questions or comments in this regard, please direct them to this office.
Sincerely,
)$d -
L. O. DelGeorge Nuclear Licensing Administrator