ML17252B136
| ML17252B136 | |
| Person / Time | |
|---|---|
| Site: | Dresden  |
| Issue date: | 02/01/1977 |
| From: | Fiorelli G NRC/RGN-III |
| To: | Brian Lee Commonwealth Edison Co |
| References | |
| BBS Ltr. #76-871, IR 1976025 | |
| Download: ML17252B136 (3) | |
Text
, __
. t i
J j
\\
i i
. J J
.. I
- .1
! 'i I
i j
l I
- . ~
l I
....1 l I I
. 1 I I
- j
~
UNITED STATES
)
NUCLEAR REGULATORY COMMISSION CENTRAL Fl LES REGION ill 799 ROOSEVELT ROAQ
. GLEN ELLYN; ILLINOIS 60137 FEB l 1977 Commom,-ealth *Edison Company Docket No. 50-249 ATTN:
Mr. Byron Lee, Jr.'.
Vice President P.O.* Box 767 Chicago, Illinois 60690 *
- Gentlemen:
- Thank you for your letter dated December 14, 1976, informing us of the new test program relating to feedwater check valve local leek-rate tests.
Your* program is presently under review by our office and has also been forwarded to our headquarters
.for a.generic review
- Your cooperation with us is appreciated *
. Sincerely yours,*
- ~** r;vp
\\..-Gaston Fiorelli, Chief Reactor. Operations and
- Nuclear Support Branch cc:
Mr. B. B. Stephenson Station Superintendent cc w/ltr dtd 12/14/76:
Central Files
- Reproduction Uni:t NRC 20b PDR
Attorney i.
. ----- -*--n.,.
' *~
i~ i r
~ *'
.e*.
e**
~~------- -.
. ----***-* **-. *-* ***--*------~- ___ *:.......... *-----*.-.* -:-~'
Commonwealth. Edison
. Dresden Nuclear Power Station R.R. #1 Morris, Illinois 60450 Telephone 815/942-2920 BBS Ltr. #76-871 Hr. James G. Keppler, Regional Dtrector Direttorate of Regulatory Operations Regi~n.I II U.
s~ Nuclear Regulatory Commission 799 Roosevelt Road Glen Ellyn, Illinois 60137
SUBJECT:
Dresden Statiori Feedwater Check Valve Local Leak-Rite Testing
REFERENCE:
Letter to J. G. Keppler from B. B. Stephens.on dated November 4, 1976 (Reportable O~currence report no. 50-249/1976-25)
Be~'ause feedwater check valve local leak-rate*tests (LLRT-'s) have repeatedly yielded excessive "as found" leakage results, a new test method has been developed which approximates as closely as possible the primary con-tainment conditions during a loss-of-coolant accident (LOCA).
The new test method involves pressurizing the volume upstream of the
- feedwater check valve with wate~.to approximat~ly 50 psig, then draining the *system and performing a LLRT utilizing isolation valve test procedures.
Current isolation valve test procedures specify a pneumatic pressure decay test as required by the Technical Specifications. *The station procedures will be, revised to reflect the new method of testing the feedwater check valves in the "as found" condition.
Development of ih~s new test method was based on typical postulated conditions following a LOCA.
The conditions selected were the design basis
- LOCA'followed by a loss.of off-site power, two failures which would 'result In the *lowest differential pressure available to seat the feedwater check valves *. For these conditions, reactor and containment pressure would be approximately 50 psig when the feedwater system pressure dropped to zerq as the result of the loss of off-site power.
Postulated LOCA'~ with less than
- design basis-size breaks would result in longer blowdown rates and potentially higher differential pressure available t6 seat the check valves following the subsequent loss of off-site power.
Sinte there would still be water on -the valves due to their position in the low point of the 1 ine, the new.
method of seating the valves with water is representative of accident conditions.
10 C.F~R~ part 50, appendix J, section I I l.C.1 specifies that each valve to be tested shall b~ closed by normal operation ~nd without any preliminary exercising or adjustments.* Feedwater check v~lve seating wi~h water-is con-*
sidered a normal operation since. the*valye is. no*rmally seated with water and a differe~tial pressure.*
Based on the results of testing performed during the Dresden Unit-3 i976 refueling outage, it is anticipated that the utilization of the new DEc 2 fl l9.l;;.
'*** test method will significantly r.e,duce the incidence of excessive "as found" leakage test results on the feedwater check valve*s.
(The method used to test the Unit-3 feedwater check valyes is described in _the refer:enced re-portable occurrence r-e-port.)
As. stated.previously, the:;*Dresden Station**LLRT procedure'.:'for the feedwater check valves will be *revised to include this new test fog met hod.
BBS :.CES :jo
/it;
~". '
.£*/
,-.-?
.... )-
/
,,~.,,.
/
~-,.
_\\
.,_. -fZ,I/;_, *',. ~ {. 1.
- _... tL* {.. \\te~penson
- Station Superintendent Dresden Nuclear Power Station cc:
Director of Inspection & Enforcement
- ~
Director of Management Information & Prbgram Control Fi Je/NRC
- 1
.. c.
~**.*
- -.. ~~
.... \\
..* -~~
- ~*-
- ..