ML20244D618
| ML20244D618 | |
| Person / Time | |
|---|---|
| Site: | Oconee, 05000000 |
| Issue date: | 12/16/1985 |
| From: | Crutchfield D Office of Nuclear Reactor Regulation |
| To: | Miraglia F Office of Nuclear Reactor Regulation |
| Shared Package | |
| ML20195F761 | List:
|
| References | |
| FOIA-87-714 GL-81-14, TAC-43643, TAC-43644, TAC-43645, NUDOCS 8601090686 | |
| Download: ML20244D618 (2) | |
Text
_ _ _ - -
i a
4p.may
+
C.
UNITED $TATES
{
e </
NUCLEAR REGULATORY COMMISSION i
,Nl,g j
8\\
l wasmucrow, o. c. 20sss s.g M /
{
(.....
Da 1 S 19P.
{
MEMORANDUM FOR: Frank Miraglia, Director, Division of PWR Licensing-B FROM:
Dennis Crutchfield, Assistant Director for Technical Support, Division of PWR Licensing-B
SUBJECT:
SEISMIC QUALIFICATION OF THE OCONEE AUXILIARY FEEDWATER SYSTEM, MPA C-14 (TAC N0' 43643/4/5)
The purpose of this memorandum is to request your approval to proceed with a plant specific backfit of Oconee Units 1, 2 and 3 in order to resolve the remaining key issue with regard to auxiliary feedwater system (AFWS) seismic qualification. Oconee is the only plant remaining under MPA C-14 for which the staff review is not complete. The staff has been negotiating this issue with Duke Power for over three years.
By memorandum from L. S. Rubenstein to Gus C. Lainas dated October 22, 1985 (Enclosure 1), 051 transmitted the safety evaluation report concerning AFWS seismic qualification for Oconee in response to Generic Letter 81-14 (tiPA C-14). That SER identified three open items which required resolution in order to demonstrate suitable AFWS seismic qualification. It was also stated in that memorandum that any modifications required at Oconee te resolve the open items were not considered to be backfits according to Draft Manual Chapter 0514 based on the fact that Generic Lette'
?4 required conformance with GDC 2 and 34 which are existing staff req.
% r.t s.
At the request of J. Stolz, we have rereviewed the SER and DSI findings regarding backfit in order to assist him in developing a course of action for expediting resolution of this issue. We have identified the primary concern regarding AFWS seismic inadequacy to be as follows.
In the event of a safe shutdown earthquake (SSE), because the circulating water system is not seismically supported, it is assumed to rupture and flood the lower elevation of the turbine building which is common to the three units.
Because the AFWS pumps for all three Oconee units are located in a common area at this elevation of the turbine building, they will flood and would be unavailable for reactor shutdown. The licensee has performed an analysis which demonstrates that the turbine building will maintain its structural The safe shutdown facility (SSF) at Oconea integrity in the event of an SSE.
is qualified to withstand an SSE but contains a single seismically qualified Therefore, a concurrent single active failure will result in no AFWS pump.
AFWS function for post-earthquake decay heat removal as specified in GDC 34.
Contact:
J. Wenniel X20462
~-
I, g*
g
& - h %,la. R Ly2 n
fp,
.i
,.L.
\\
_,; y Based on our discussions with the licensee and previous site visits, we believe this issue can be resolved.by installation of seismically supported waterproof walls around the three turbine driven AFWS pumps. This modification in con-junction with the SSF would assure at least one AFWS pump for shutdown of the three units in the event of an SSE and concurrent single active failure.
Alternatively, the licensee could add a second seismically qualified pump to the SSF with sufficient capacity to shutdown all three Oconee units.
We have also reconsidered the initial DSI determination in the October 25, 1985 memorandum that resolution of this issue does not constitute a plant specific backfit. Contrary to that finding, it is our opinion that because the original licensing basis for Oconee did not include compliance with GDC 2 and 34 for the AFWS, this issue is a backfit. It appears clear that Generic i
Letter 81-14 itself is a staff approved generic backfit of these GDC. There-fore, because we see no means of resolving this issue without modifications at Oconee, we are proposing a plant specific backfit. We recomend this action despite the staff's previous approval of the SSF which omitted consideration of the itgle failure criterion (memorandum L. S. Rubenstein to Gus C. Lainas det w December 29, 1982, Enclosure 2) with only a single pump in order to achieve comparabl( post-earthquake safe shutdown capability to that provided at other PWRs in accordance with the criteria of Generic Letter 81-14 We further believe this action should be taken ir view of the importance of both earthquakes and the auxiliary feedwater system to the risk of core melt.
We understand that before a backfit letter is transmitted to the licensee, the staff must develop a justification with the appropriate regulatory analysis (cost / benefit evaluation). We believe we can provide this information in a reasonable time frame with assistance from DSR0 (RRAB). However, before we proceed with this effort, we request your approval of our position. We are available to discuss this matter with you further if desired.
h.
c Dennis Crutch i 1,
sist nt Director for Technical Sup rt Division of PWR Licensing-B End )sures:
As Stated cc w/ enclosure:
F. Schroeder J. Stolz
- 0. Parr j
G. Holahan j
F. Congel J. Wermiel H. Nicholaras J. T. Beard 1
I