ML20205N363
| ML20205N363 | |
| Person / Time | |
|---|---|
| Site: | Sequoyah  |
| Issue date: | 10/31/1988 |
| From: | Gridley R TENNESSEE VALLEY AUTHORITY |
| To: | NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM) |
| References | |
| NUDOCS 8811040091 | |
| Download: ML20205N363 (5) | |
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TENNESSEE VALLEY AUTHORITY CH ATTANOOG A, TENNESSEE 37401 SN 1578 Lookout Place 06T 311988 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Hashington, D.C.
20555 Gentlemen:
In the Hatter of
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Docket Nos. 50-327 Tennessee Valley Authority
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50-328 SEQUOYAH NUCLEAR PLANT (SON) UNITS 1 AND 2 - CLARIFICATION OF THE 40-YEAR QUALIFICATION TESTING OF SILICONE RUBBER-INSULATED CAllLES
References:
1 TVA letter to NRC dated July 6, 1988, "Sequoyah Nuclear Plant (SQN) Units 1 and 2 Year Qualification Testing of Stitcone Rubber-Insulated Cables" 2.
NRC letter to TVA dated September 2, 1988, "Silicone Rubber Insulated Cable Test Program - Sequoyah Nuclear Plant, Units I and 2 (TACS R00386, R00387)"
By letter dated July 6, 1988 (reference 1), TVA submitted its test program for the 40-year qualification testing of the silicone rubber-insulated cables inside containment for SQN units I and 2.
Reference 2 included the staff's safety evaluation report (SER) on this test program, which was verified by the staff to adequately address NRC's requirements provided that TVA accepted the clarifications identified within the SER.
This letter provides r with TVA's aueptance of these clarifications, which are listed and ussed in the enclosure.
Based upon the acceptance of these ifications by TVA, the proposed cable test program meets NRC's requirements and is thereby acceptable as stated by reference 2.
Please direct quest!or; concerning this issue to B. A. Kimsey at (615) 870-6847.
Very truly yours.
TENNESSEE VALLEY AUTHORITY
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ADOCK 05000327 ppg An Equal opportunity Employer
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Ms. S. C. Black. Assistant Director I
for,*rojects i
TVA Projects Division U.S. Nuclear Regulatory Commission One White Flint. North t
11555 Reckville Pike Rockville,' Maryland 20852 I
Mr. F.-R McCoy. Assistant Director for Inspection Programs TVA Projects Division U.S. Nuclear 9egulatory Commission Region II l
101 Harletta Street. NW, Suite 2900 l
Atlanta, Georgia 30323 Sequoyah Resident Inspector Sequoyah Nuclear Plant 2600 Igo9 Ferry Road Soddy Daisy, Tennessee 37379 I
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i g s e i ENCLOSURE In the September 2, 1988 letter from NRL to TVA, the staff stated that it had reviewed TVA's proposed test program ahd determined that the program met the requirements outlined in the staff's letter of May 25, 1988, with the following clarifications:
"1.
TVA has defined the scope of the test program to include only the cables which are covered by 10 CFR 50.49, Category A and B.
The staff requires that all 10 CFR 50.49 cables be included in the program.
TVA has informed the staff that all 10 CFR 50.49 cables are covered by Category A and B.
However, to clarify the matter TVA will delete the reference to Category A and B.
- 2. ; ' Sample Selection, Size and Removal Process;' TVA should add a step between (4) and (5) to state that the cable sample will be solected from a conduit with no less than 3 cables, unless justified.
TVA has informed the staff that their selection criterla already include this lu m and will add the criteria to the test program.
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- 3. ; ' Resolution of Test anomalies and Test failures;' 3rd
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paragraph:
TVA should add a requirement that, as soon as the determination is made that a test anomaly is in fact an. actual test R
failure NRC will be promptly nottfled of such determination.
TVA has i
agreed to add this requirement to the test program."
l TVA's response to these clarifications is as follows:
1 1.
TVA used these terms (categories A and B) because these cables are associated with equipment that is required to mitigate the consequences of l
a 10 CFR 50.49 event.
No mention has been made of cables associated with i
category C equipment because that equipment, by definition, does not perform a safety-related furicticn.
This approach is consistent with other I
cable-related programs.
For example, environmental qualification for j
accident service is only required for cables associated with category A 1
and B equipment.
In similar fashion, the replacement of silicone i
rubber-insulated cables manufactured by American Insulated Wire (A!H) was
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limited to those cables required for 10 CFR 50.49 (i.e., categories A and B).
J It should be noted that TVA's use of this terminology is consistent with t
i NUREG-0588.
Speelftc definitions taken from Appendix E, section 2 are as j
shown belo1.
1 1
Catygory A:
"Equipment that will experiere:. the environmental conditions of ciesign basis accidents for which it must function to mitigate said I
acchients, and that will be cualified to demonstrate operability in the accident environment for the time required for accident mitigatle') with safety margin to failure."
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Category _B:
"Equipment that will experience environmental conditions of design basis 4ccidents through which it need not function for mitigation of said accidents, but through which it must not fall in a manner detrimental to plant safety or accident mitigation, and that will be quallfled to demonstrate the capability to withstand any accident environment for the time during which it must not fail with safety margin to failure."
Category C:
"Equipment that will experience environmental conditions of design basis accidents through which it need not function for mitigation i
of said accidents, and whose failure (in any mode) is deemed not detrimental to plant safety or accident mitigation, and need not be qualified for any accident environment, but will be r.uallfled for its non-accident service environment."
f At Watts Bar Nuclear Plant, the intent of the screening process was to I
identify and remove for testing worst-case specimens from the population of silicone rubber-insulated cable installed on conduit inside unit I containment from circuits required for 10 CFR 50.48 (i.e., categories A and B).
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t The limitation of the screening to unit I wa> discussed with the NRC by l
TVA representatives in a May 2, 1988 meeting in NRC's Rockville, Maryland offices.
This limitation was justified because the two units are identical, the sampling would result in the selection and testing of multiple specimens, and the degradation was postulated to be widespread rather than a single random event.
i Sampling of cables manufactured by Rockbestos followed the above process.
However, in the case of cables manufactured by Anaconda, TVA believed that l
its family of 10 CFR 50.49 category A and B cables was not sufficiently large and therefore expanded its sampling to include all class IE silicone r
rubber-insulated cables in conduit in either unit I or unit 2, regardless of category (i.e., A, B, or C).
In conclusion, TVA's test program does consider all silicone rubber-insulated cables whose operations are required to mitigate the consequences of a 10 CFR 50.49 event and whose failure could be
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i detrimental to plant safety or accident mitigation.
With this
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understanding, TVA is in agreement that the "categories A and B" r
designation can be deleted.
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2.
TVA hereby modifies enclosure 2 of reference ! to include the following step:
4A.
The cable sample will be selected from a conduit with no less than three cables, unless justified.
Note:
This requirement was made part of the selection criteria; however, one of the worst-case condults selected tontained only two cables.
The use of these cables as test specimens is justified in Nuclear Engineering Calculation WB-PEVAR88-6004 and was discussed in a July 12, 1988 telephone conversation among Hukam Garg (NRC), Kent Brown (TVA/EEB), and Barry Kimsey (50N/ Licensing).
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, 3. of reference 1 (3rd paragraph, first sentence) should be revised to read, "In the event that a test anomaly is determined to be an actual test failure, a condition adverse to quality report (CAQR) will be initiated and the NRC will be promptly notifled."
TVA also agrees to this revision or clarification of its cable test program.
In conclusion. TVA has aareed to make the above clarifications to its cable 1
test program as requested by NRC in reference 2.
Based on these revisions, it is TVA's understanding that its proposed cable test program has been found acceptable based on these revisions as stated in reference 2 Unless notification to the contrary is received.
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