ML093220952
| ML093220952 | |
| Person / Time | |
|---|---|
| Site: | Byron  |
| Issue date: | 11/18/2009 |
| From: | Pederson C NRC/RGN-III |
| To: | Pardee C Exelon Generation Co, Exelon Nuclear |
| References | |
| EA-09-247, IR-09-003 | |
| Download: ML093220952 (5) | |
See also: IR 05000455/2009003
Text
UNITED STATES
NUCLEAR REGULATORY COMMISSION
REGION III
2443 WARRENVILLE ROAD, SUITE 210
LISLE, IL 60532-4352
November 18, 2009
Mr. Charles G. Pardee
Senior Vice President, Exelon Generation Company, LLC
President and Chief Nuclear Officer (CNO), Exelon Nuclear
4300 Winfield Road
Warrenville IL 60555
SUBJECT:
RESPONSE TO DISPUTED NON-CITED VIOLATION BYRON STATION,
UNIT 2, INSPECTION REPORT 05000455/2009003
Dear Mr. Pardee:
On September 8, 2009, Mr. Daniel J. Enright, Exelon Generation Company, LLC
(Exelon), Byron Station, Unit 2 provided a response to an NRC Inspection Report issued
on August 7, 2009, concerning activities conducted at your facility. Specifically, the Exelon
letter contested one non-cited violation (NCV) contained in the inspection report, namely
NCV 05000455/2009003-01, associated with the Failure to comply with Technical Specification (TS) 3.4.13.B reactor coolant system (RCS) pressure boundary leakage." By our letter dated
October 8, 2009, the NRC acknowledged your letter and advised you that we were evaluating
your reply and would inform you of the results of our evaluations. We have completed our
review of your response.
In the September 8, 2009 letter, your staff stated that on June 24, 2009, Byron Station Unit 2
correctly complied with TS 3.4.13.B. Specifically, the leakage from the process sampling line
was an isolable reactor coolant system pressure boundary leak and therefore excluded from
TS 3.4.13 pressure boundary limit. Your staff provided information to support this position,
including:
an interpretation of the definition of a "nonisolable fault and inferred definition of isolable
fault;
the potential for uncontrolled RCS leakage growth and further deterioration did not exist in
this process line fault condition because an isolation valve upstream of the fault was closed;
the leakage was bounded by 0.5 gpm, the design seat leakage past this valve's seat. At the
time of the event, the leakage past the valve seat was very small;
the very small leakage past the isolation valve's seat was acceptable because leak tightness
(zero leakage) is not a requirement as evidenced by allowed leakages for other TS valves;
and
C. Pardee
-2-
the NCV is not consistent with how the NRC approached similar situations at other utilities.
NRC Staff's Review:
The NRC staff reviewed the information you provided to determine whether the leakage from
the process sampling line should be classified as a pressure boundary leak as stated in the
Inspection Report or as identified leakage as presented in your September 8, 2009, letter.
These staff members were independent of the initial inspection effort. The staff members
reviewed several documents including Regulatory Guide 1.45, Guidance on Monitoring and
Responding to Reactor Coolant System Leakage, and NUREG 1431, Standard Technical
Specifications Westinghouse Plants, recordings of discussions associated with a request for
a Notice of Enforcement Discretion, Action Report 000934800, numerous emergency
notifications, and licensee events reports. After careful consideration of the information you
provided, we have concluded that the violation occurred as stated in the inspection report.
Pressure boundary leakage as defined by TS 1.1 is LEAKAGE (except SG [steam generator]
LEAKAGE) through a nonisolable fault in an RCS component body, pipe wall, or vessel wall.
On June 26, 2009, your staff identified a pinhole in a weld on a reactor coolant system piping
connection between a closed sample isolation valve (2PS9350B) and the closed inboard
containment isolation valve (2PS9355B). The source of the leakage was pressure boundary
piping. Your staff provided information with respect to the definition of nonisolable. The staff
agrees that an isolation device in a piping system could be used to isolate a leak such that the
leak would not be considered pressure boundary leakage as defined above. The staff agrees
the leakage would be bounded by the design seat leakage of about 0.5 gpm during the periods
of time the sample isolation valve (2PS9350B) remained closed. However, prior to the repairs
on June 26, the as-found position of the sample isolation valve (2PS9350B) did not isolate the
pressure boundary flaw, that is, leakage continued through the weld.
Your letter presented a position that valve seat for 2PS9350B did not need to be leaktight as
evidenced by the allowance of leakage past pressure isolation valve seats. The staff agrees
that NUREG 1431, Standard Technical Specifications Westinghouse Plants, specifically states
that the leakage past the pressure isolation valve seats is not pressure boundary leakage;
however, no such distinction is made with other valves. The leakage limit for the pressure
isolation valves is an indication that the pressure isolation valves themselves are degraded or
degrading and is not indicative of material degradation of a pressure retaining component,
piping wall or vessel wall.
Although the leakage through the weld was very small, the staff concluded the leak through the
pinhole in the weld was a breach in the pressure boundary and indicative of degradation of the
material of pressure retaining components. Therefore, the leak through the pinhole in the weld
constituted pressure boundary leakage and the violation as stated is valid. With respect to an
apparent inconsistency with how the NRC approached similar situations at other utilities, each
situation was evaluated independently. The staff does believe that the Standard Technical
Specifications should be clarified to avoid future confusion on this issue. Accordingly, the staff
will engage the Technical Specifications Task Force, and work with them to provide a solution,
which can be made available for adoption by licensees through the NRC's Consolidated Line
Item Improvement process.
C. Pardee
-3-
In accordance with 10 CFR 2.390 of the NRC's "Rules of Practice," a copy of this letter and your
September 8, 2009, response will be available electronically for public inspection in the NRC
Public Document Room or from the NRC's document system (ADAMS), accessible from the
NRC Web site at http://www.nrc.gov/reading-rm/adams.html.
Sincerely,
/RA/
Cynthia D. Pederson
Deputy Regional Administrator
Docket No. 50-455
License No. NPF-66
cc w/encl:
Distribution via ListServ
C. Pardee
-3-
In accordance with 10 CFR 2.390 of the NRC's "Rules of Practice," a copy of this letter and your
September 8, 2009, response will be available electronically for public inspection in the NRC
Public Document Room or from the NRC's document system (ADAMS), accessible from the
NRC Web site at http://www.nrc.gov/reading-rm/adams.html.
Sincerely,
/RA/
Cynthia D. Pederson
Deputy Regional Administrator
Docket No. 50-455
License No. NPF-66
cc:
Distribution via ListServ
DOCUMENT NAME: G:\\Byron\\disputed violation letter.doc
Publicly Available Non-Publicly Available
Sensitive
Non-Sensitive
To receive a copy of this document, indicate in the concurrence box "C" = Copy without attach/encl "E" = Copy with
attach/encl "N" = No copy
OFFICE
RIII
RIII
RIII
RIII
RIII
NAME
RSkokowski:dtp AMStone
SOrth *PL
for*(see below)
SWest
CPederson
DATE
11/10/09
11/10/09
11/10/09
11/16/09
11/18/09
OFFICIAL RECORD COPY
also indicates that NRR and OE have reviewed this position and concur
Letter to C. Pardee from C. Pederson dated November 18, 2009.
SUBJECT:
RESPONSE TO DISPUTED NON-CITED VIOLATION BYRON STATION,
UNIT 2, INSPECTION REPORT 05000455/2009003
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