ML18033B379
| ML18033B379 | |
| Person / Time | |
|---|---|
| Site: | Browns Ferry  |
| Issue date: | 05/31/1990 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML18033B375 | List: |
| References | |
| NUDOCS 9006210241 | |
| Download: ML18033B379 (4) | |
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UNITED STATES "NUCLEAR REGULATORY COMMISSION WASHINGTON, O. C. 20555 SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION EHPLOYEE CONCERN 22600 SEISHIC INTERACTION DESIGN TENNESSEE VALLEY AUTHORITY BROWNS FERRY NUCLEAR PLANTS DOCKET NOS. 50-259 50-260 AND 50-296 1.0 SUBJECT Concern for lighting fixtures becoming missiles during an earthquake was introduced in an anonymous letter to the NRC staff dated Hay 9, 1985.
Subsequently, TVA expanded the scope to ensure that all non-seismically supported (or Class II) components will not damage seismic (Class I) equipment when subjected to an earthquake.
2.0
SUMMARY
OF ISSUE The employee concern addresses lighting fixtures not being properly restrained and caged to prevent them from becoming free or swinging missiles during seismic events, thus becoming a potential for damaging nearby seismic equipment through seismic interaction.
This seismic interaction was extended to all non-seismic (Class II) equipment and components.
- 3. 0 EVALUATION The staff previously reviewed for the Sequoyah Nuclear Plant (SQN), investi-gations and pre-restart corrective actions performed by TVA to resolve the concern in Element Report 226.0-S(N and found TVA's restar t resolution to be acceptable (Hemorandum from G.
G.
Zech to S. A. White "Staff Safety Evaluation Report - Sequoyah Nuclear Plants,"
dated Harch ll, 19&8).
The Element Report 226.0-SgN is primarily in the area of potential missile effects of lighting fixtures.
The staff approval was based on the SgN corrective action plan.
Element Report 226.0 Rev.
3 dated November 5. 1987, includes the broader scope of seismic interaction design beyond lighting fixtures.
During late 1985 and early 1986, several significant condition reports (SCRs) were generated for the Browns Ferry Nuclear Plant (BFN).
They indicated that an engineering evaluation was not performed which would ensure that various Class II features cannot degrade the integrity of Class I features as a
result of loadings caused by earthquake ground motions.
In Duly 1986, TVA issued SCR BFN HEB 8605 to serve as a single generic significant condition report to reduce, if not eliminate, the writing of additional SCRs on the subject of non-seismic/seismic interaction (II/I).
Conditions Adverse to guality (CA/) Engineering Report for SCR BFN HEV 8605 stated that this SCR is intended to address all BFN Class II features and their components when they are located near Class I features.
The Engineering Report stated that the SCR is also intended to address potential damage to VOoaaioaei 9005SS PDR ADOCV, 05000259 P
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Class I features caused by impact from failure and excessive movement of Class II lighting fixtures.
The report concluded that'no documentation exists to assure that the integrity of Class I features has been considered in the design of Class II features; neither does documentation exist that would assure that the design of Class I features recognizes the presence of Class II features.
- Further, the potential exists that failure of Class II features could degrade the integrity of Class I features as a result of a seismic event.
TVA's Division of Nuclear Engineering (DNE) is developing a program to evaluate seismic-induced effects of Class II items on Class I components.
The program consists of two phases.
Phase I establishes acceptance criteria, develops procedures, and defines work scope for evaluation of seismic-induced effects of Class II items on Class I components.
Phase II implements the program.
Phase I already has been awarded to two contractors.
TVA, after reviewing the program, will select one contractor for Phase II.
Phase II also will include development of a long-term program for the design of future modifi-cations at Browns Ferry to prevent problems due to seismic interaction between Class I and Class II components.
TYA's corrective action plan under this issue further committed the following:
Develop a seismic interaction program to evaluate seismic-induced effects of Class II items including lighting fixtures on Glass I components.
Perform a walkdown to identify II/I seismic interaction between as-built Class I and Class II components.
Develop an evaluation methodology and provide fixes as required.
Glass II/I evaluation for seismic interaction between as-built Class I and Class II components will be performed under the Unresolved Safety Issue (USI) A-46 program as a post-restart activity.
A procedure for controlling future II/I seismic interaction will be developed prior to completion of the baseline A-46 effort.
This procedure will meet the nore general requirements of design interface document CEB-DI-121. 03.
The staff determined that the above described corrective action plan is consistent with the NRC staff's resolution to Unresolved Safety Issue A-46, "Seismic gualification of Equipment in Operating Plants,"
and is thus acceptable.
- 4. 0 CONCLUSION Based on the discussion
- above, the staff concludes that TVA's corrective action plan pertaining to seismic interaction design as described in the Element Report 226.0 dated November 5, 1987 is acceptable.
,ra.
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