ML20096C784
| ML20096C784 | |
| Person / Time | |
|---|---|
| Site: | Byron, Braidwood  |
| Issue date: | 05/11/1992 |
| From: | Simpkin T COMMONWEALTH EDISON CO. |
| To: | Davis A NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| References | |
| NUDOCS 9205140287 | |
| Download: ML20096C784 (3) | |
Text
~
i V
I-N h h' h-(N
./
~ \\ 5mmonwaalth Edison
{l3 uJO Opus Place f Downes Grove, Illinois 60515 May 11,1992 i
DLp Li.:.%
Wy((D l [* UN Eb[
/
Mr. A.B. Davis Regional Administrator
!Qi D.D U.S. Nuclear Regulatory Commission
" gg~L Region lli 799 Roosevelt Road Glen Ellyn,IL 60137
Subject:
Byron /Braidwood Kerotest Valve F,9 placement Program NRC Docket Nos. 50-454,50-455,00-456,50-457
Reference:
February 14,1989 S.C. Hunsader letter to A.B. Davis
Dear Mr. Davis,
The referencel provided CEOo's intention relative to the replacement of fotest valves at the Byron and Braidwood Stations. This letter was provided in
.esponse to conversations between T. J. Ma! man and E.G. Greenman regarding Braidwood Station Reactor Coolant System (RCS) leakage.
In the letter, CECO recognized "...that tFe RCS leak rate at Braidwood Station, as well as at Byron Station, is at times higher than that for similar plants in Region Ill". ' Although there were various causes, "A major contributor has been the failure of certain Y-pattern packless metal diaphrarn (PMD) [Kerotest) valves
" As a part of the program to reduce the leakage, a decision was made to replace or eliminate the currently installed Kerotest valves.
CECO has reevaluated the Kerotest Valve Replacement Program at Byron and Braidwood in light of recent operating conditions. As a result, the Kerotesi Valve Rep lacement Program scope and schedule are being redefined. This letter
. provides details regarding the chaages to the Program.
Changes v.ill involve citsure of some projects in the near future. All information which has been gathered or produced will be retained for future use.
Originally, the Kerotest Valve Replacement Program was developed to address the concerns over higher than normal leakage rates. During initial review, it was determined that there were 240 Kerotest valves in the RCS and approximately 430 more in other systems (per unit); Since failure of some non-RCS valves could cause detrimental operating. consequences, the Program was designed to encompass any Kerotest valve in a sensitive application.- To date, o
approximately 20 valves at each station have been replaced under this program.
'3 The replaced valves are associated with the seal injection filters and the safety l
injection accumulator fill lines.
[Y
\\
l 9205140287 920511 PDR ADOCK 05000454 P
PDR 11193')-
ZNLD/1571/1 r
~
Mr. A.B. Davis May 11,1992 Since the occurrence of the original conversations between T.J. Malman and E.G. Greenman, two significant operating changes have been noticed. These are:
(1)
The calculated unidentified leak rate (which was greater than 0.5 gpm a the time of the oi.ginal conversations) was reduced by rnore than 50%
following a maintenance outage specifically directed at identifying and correcting RCS leakage. Currently the unidentified leak rate remains wel: below the Technical Specification limits at all units.
(2)
The f ailure rate of Karotest valves has decreased. In addition, further improvements may be possible with additional training on the design and operation of Kerotest valves. Appropriate training has been conducted at both stations.
In addition, the elimination of the RTD bypass manifolds is planned for future refueling outages 1ese modifications will eliminate numerous Kerotest valves.
l As a result o mese operating changes and planned modifications,it has become apparent inat the original program scope was unnecessarily expansive, and the continuance of the program as originally envisioned will not be cost effective. The revised action pian for the remaining PMD valves is presented below.
The action plan includes five categories for future replacements of valves which have been identified as replacement candidates. These categories are:
L (1)
Minor Change Request (MCR) engineered but valve not installed, and installation to continue on schedule.
l (2)
MCR engineered but valve not installed, and installation to be rit on hold pending failure of installed valve.
(3)
MCR identified but not engineered, and installation to be put on hold pending failure of installed valve. Note that engineering will not be started for these.
(4)
MCR awaiting Modification Committee review for critical applications j
where engineering will be done in tne future, but installation will be put on hold pending failure of installed valve.
(5)
Valves which have not been scheduled for replacement will be evaluated on a case-by-case basis. Possible options include: perform engineering and install proactively, perform enginoering and hold installation until there is evidence of impending failure, or monitor perfom:ance for a limited time before deciding on a course of action.
ZNLD/1571/2 J
~
l
.s Mr. A.d. Davis May 11,1992 The program will be ievised as necessary in the future to.accomrnodate new reptaraments. One revision already under consideration is like-for like repl0 cement (with Kerotest valves). This decision was made based upon new information which suggests that the valves may not be as failure prone as was originally believed in surrmary, the Kerotest Valva Rep;acement Program is being revised based upon changing operating conditions. Much of the ongoing work wi;; be stopped and projects closed our in a timely, organized fashion. All engineering information gathered or produced to date shall be retained for future reference should the noed arise.
Please address any questions concerning this matter to this office l
Sincerely, Qfw w N s'
~
T.W. Simpkin Nuclear Licensing Administrator cc:
B. Clayton. Rlli c
T. Hsia, NRR R. Pulsifer, NRR l-W. Kropp - SRI, Byron S. Dupont - SRI, Braidwood L
j ZNLD/1571/3 Y