ML18036A543
| ML18036A543 | |
| Person / Time | |
|---|---|
| Site: | Browns Ferry  |
| Issue date: | 03/05/1992 |
| From: | Ross T Office of Nuclear Reactor Regulation |
| To: | Kingsley O TENNESSEE VALLEY AUTHORITY |
| References | |
| TAC-M68517, TAC-M68518, TAC-M68519, NUDOCS 9203110276 | |
| Download: ML18036A543 (10) | |
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+**p 4 UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D. C. 20555 March 5, 1992 Docket Nos.
50-259, 50-260, and 50-296 Mr. Oliver D. Kingsley, Jr.
President, Generating Group Tennessee Valley Authority 6N 38A Lookout Place 1101 Market Street Chattanooga, Tennessee 37402-2801
Dear Mr. Kingsley:
SUBJECT:
REQUEST FOR ADDITIONAL INFORMATION ON STATION BLACKOUT FOR BROWNS FERRY (TAC NOS.
- 68517, 68518, AND 68519)
On January 8,
- 1992, the Tennessee Valley Authority (TVA) and NRC staff conducted a conference call to discuss the content of TVA's letters dated August 13 and December 2,
1991.
These letters were submitted in response to the staff's safety evaluation dated July 11, 1991 with regard to Station Blackout (SBO) at the Browns Ferry Nuclear Plant (BFNP).
During this call, the staff asked TVA to clarify particular aspects of its SBO responses, and to address some additional staff concerns.
As a consequence of this call, the staff requested TVA to provide additional information to support the staff's SBO evaluation of BFNP.
TVA committed to provide this information in a formal response.
A detailed list of the staff's questions and/or concerns is enclosed.
TVA should provide their responses as soon as possible in order to aid the staff in expediting its evaluation of BFNP's compliance with 10 CFR 50.63 (i.e.,
SBO rule).
Based on recent discussions with BFNP Nuclear Licensing, the staff expects TVA to submit their SBO responses for BFNP (Units 1, 2, and 3) no later than March 31, 1992.
TVA is to notify the 9203110276 920305 PDR 'DOCK 05000259 PDR
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Hr. Oliver D. Kingsley staff if circumstances should change such that meeting this date is impracticable.
This requirement affects 9 or fewer respondents and, therefore, is not subject to Office of Hanagement and Budget review under P.L.96-511.
Sincerely,
Enclosure:
As stated Thierr H. Ross, Senior Project Hanager Project Directorate II-4 Division of Reactor Projects I/II Office of Nuclear Reactor Regulation cc w/enclosure:
See next page OFC NAHE DATE PDI I-4LA HSanders 92 PDI I-4PH TRoss:as d
9",5 92 PDI I-4PH JWiilli 5
2 PDII 4D FHe on 3 5 92
Enclosure
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Request for Additional Information Regarding Blackout at the Browns Ferry Nuclear, Plant A.
Class lE Battery Capacity 1.
Provide completion schedule foi DC-power system modifications.
2.
3.
Provide results from the modified battery capacity calculations for multi-unit operation using the new safety-related batteries (actual calculations should be made available at the TVA Rockville office).
Justify all assumptions, and address any applicable non-conservatisms or concerns identified in the staff's safety evaluation (SE) (e.g.,
Section 2.2.2).
In Enclosure 1 (on page 1 of 3) of TVA's response dated December 2,
- 1991, "the 120V AC Reactor Core Isolation Cooling (RCIC) system controls... will be transferred to an appropriate source."
Identify this source and verify that it will be available during the four-hour duration of SBO.
4.
5.
6.
Following the four-hour SBO event, power will be restored
=
from either offsite or onsite (i.e.,
emergency diesel generators (EDG)) sources.
Since EDG restart and switchyard circuit breaker closure are powered from different sources, TVA should consider both scenarios in order to properly bound the end of the postulated SBO event.
TVA is requested to verify that Browns Ferry can accommodate the most limiting power restoration scenario (e.g., calculations that confirm adequate DC power supplies to restart EDGs).
TVA used a design margin of 1.00 in its battery calcula-tions.
This is inconsistent with the guidance of IEEE Standard 485, which recommends
- 1. 10 1. 15.
Provide justification for using an apparently non-conservative design margin.
TVA assumed an initial battery room temperature of 76'F.
This is inconsistent with the guidance in NUHARC 87-00 (Section 7.2.2).
Provide rationale for deviating from accepted NUMARC guidance.
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B.
Containment Isolation 1.
In letters dated August 13 and December 2,
- 1991, TVA committed to re-evaluate the containment isolation valves (CIV) in accordance with the exclusion criteria of Regulatory Guide (RG)
- 1. 155.
List all CIVs, indicating those that can be excluded (specifying applicable RG 1. 155 exclusion criteria) and those that can not.
C.
Effects From Loss of Ventilation l.
In letters dated August 13 and December 2,
- 1991, TVA committed to revise its heat-up calculations based upon staff recommended input data (Section 2.2.4 of staff SE).
TVA is requested to'rovide the results of its modified heat-up calculations (actual calculations to be made available at the TVA Rockville office) for areas containing SBO equipment (e.g.,
HPCI/RCIC rooms, the control room, drywell, etc.).
Initial inputs, assumptions, and computer codes used in these calculations are to be identified.
Equipment qualification temperatures for each area also need to be provided.
D.
guality Assurance 1.
Confirm that all of the equipment and components needed during an SBO event are specifically identified and covered by a quality assurance program consistent with the guidance of RG 1.155.
Distribution 14-E-4 14-H-3 15-B-18 Oocket Fi.l~e NRC PDR Local PDR S.
Varga G. Lainas F.
Hebdon B. Milson RII C. Patterson RII H. Sanders T.
BFN Rdg. File L. Reyes RII
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