ML20082J077
| ML20082J077 | |
| Person / Time | |
|---|---|
| Site: | Sequoyah  |
| Issue date: | 08/22/1991 |
| From: | Joshua Wilson TENNESSEE VALLEY AUTHORITY |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| TAC-77129, TAC-77130, NUDOCS 9108270137 | |
| Download: ML20082J077 (4) | |
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-e he i August 22, 1991 U.>. Nuclear Regulatory Commission ATTN:
Document Contral Desk Washington, D.C.
20555 Gentlemen:
In the Matter of
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Docket Nos. 50-327 Tennessee Valley Authority
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50-328-SEQUOYAH NUCLEAR PLANT (SQN) - CABLE TEST PROGRAM (CTP) - DISPOSITION OF CALCULATION SQN-CSS-Oll.(TAC NO. 77129/77130)
References:
1.
TVA letter to NRC dated January 25, 1991, "Sequoyah Nuclear Plant (SQN) - Units 1 and 2 - Look-Back Review of Cable Issues (TAC No. 77129/77130)"
2.
TVA letter to NRC dated November 20, 1987, "Sequoyah Nuclear Plant (SQN) Units 1 and 2 - Cable Test Program Procedures, Data, and Results" 3..
TVA letter to NRC dated July 31, 1987, "Sequayah Nuclear Plant (SQN) Units 1 and 2 - Revised Cable Test Program" This letter and enclosure provide the summary of tne disposition of TVA's Calculation SQN-CSS-Oll.
Calculation SQN-CSS-011 war, intended to document the basis for not introducing water into all sections of conduits during the 1987 testing for pullby and jamming concerns contained in Reference 3.
.This calculation was identified in Reference 1 as one of the three unissued calculations used to support Sequoyah's 1987 CTP. Calculation SQN-CSS-Oll was previously referenced in :he cable test report that was submitted to the staff by Reference 2.
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2 U.S. Nuclear Regulatory Conunission 1
August 22, 1991 Please direct questions co..cerning this issue to K. C. Weller at (615) 843-7527.
Very truly yours.
TENNESSEE VALI.EY AUYHORITY (h
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W11 son Enclosure cc (Enclosure):
Mr.
D.
E. LaBarge, Project Manager U.S. Nuclear Regulatory Comission One White Flint, North 11555 Rockville Pike Rockville, Maryland 20852 NRC Resident inspector Sequoyah Nuclear P' ant 2600 Igau Ferry Road Soddy Daisy, Tennessee 37379 Mr.
B. A. Wilson, Project Chief U.S. Nuclear Regulatory Comission Region I:
101 Marietta Street, NW, Suite 2900 Atlanta, Georgia 30323
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V ENCLOSURE DISPOSITION OF CALCULATION
.SQN-CSS-011 Background' In July 1981, TVA' committed to high-potential test certain worst-case cable and/or conduit-configurations to determine if damage was sustained because of-
-poor pulling practices or severe conduit configurations.
Theae. tests were to j
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be conducted with water _ introduced into the conduit where feasible to ensure that if damage existed,.it would be close to the electrical ground plane. TVA stated in the July 31~, 1987, letter to NRC that justification for not introducing water into all sect!.ons of conduits shall be documented on a case-by-case basis, n
Calculation SQN-CSS-011 was to document the basis for not introducing water into_a_ conduit selected for testing. These decisions were made in consideration of whether the addition of water would create a hazard to
-safety-related equipment or personnel or would spread ~ contamination, and in consideration for the ability to drain the conduit.
Although; Calculation SQN-CSS-011 was referenced in the cable test report submitted by TVA to _ NRC in the November 20,-1987, letter as if it had been issued, it was only-completed through the preparation and checking phase.
There is no_ evidence that the calculation received independent review.
- TVA has-evaluated the-potential impact of nonissuance of.SQN-OSS
oon the:
SQN Cable Test Program-(CTP). 1As described below. TVA has concluded that the nonissuance of Calculation SQN-CSS-011 does not.af fect the SQN CTP.
Disposition The value of Calculation SQN-CSS-Oll to the 1987 CTP has been overcome by events with regard.to cable damage attributable to pullbys.
Following the discovery _'of. errors in unissued Calculation SQN-CSS-009, a pullby; reevaluation effort was performed, which identified and teranked a population of worst case conduita for pullby damage. Under that effort, the 1987_ tested conduits were determined =to not constitute worst-case conf.iguraticus.
Acceptability of thisfreevaluation program, discussed in an October 5, 1990, creting between TVA and NRC and followed by an October-23, 1990. submittal from TVA to NRC, is based'upon: -(1) verified reranking-derived from configuration-based methodology, (2) successful wet testing performeu at Browns Ferry Nuclear Plant for conduit configurations bounding the newly determined SQN worst-case configurations, (3) committed additional testing -
during the Unit i Cycle:5 outage of SQN's new top three worst-case conduit configurationa.(one conduit wet with unshleided~ cables and two dry with
. shielded cables), (4) successful. SQN dry and partially wetted testing (largely l
multiconductor cables)' completed t'o date, (5) generally f avorable pulling practices and conduit configurations, and (6) absence of indication, of-the use of parachute cord. All of these f acts reinforce the_ acceptability of cable a
installations at SQN.
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TVA also evaluated the effect of nonissuance of-Calculation SQN-CSS-011 on.the jamming test' program. -In that calculation, determination of-ability to-wet
- test conduits is partly based upon subjective engineering judgements of what constitutes a reasonable effort to wet the conduit.. TVA has performed
- I detailed reviews that included walkdowns and inspections of the 15 condutta
. tested for jamming concerns and comparisons-with the isometric drawings in
- Calculation SQN-CSS-Oll.
The 1987 criteria used in Calculation SQN-CSS-011 for determining which conduits.should be wet tested-were-uti.117ed to-determine the applicabic segments. -Diacussions were also conducted with personnel-involved in the 1987 testing of jammed conduits. This review of Calculation SQN-CSS-011 concludes that the judgements appear reasonable, recognizing that the judgenents= applied in-1991 -in comparison with 1987, may differ.
In summary, the noalssuance of Calculation SQN-CSS-011 has-no impact on
. operability determinations performed for SQN in 1990 or ultimate resolution of the SQN cableLissue.
The Calculation SQN-CES-011Lhaa keen archived in TVA's Records and Information Management System (RIMS) for L storical purposes.
In addition SQN's calculation cross-reference Information system has been annotated-to reflect the RIMS na.nber of this disposition so that -the documentation can be retrieved, it needed.
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