ML16342D043
| ML16342D043 | |
| Person / Time | |
|---|---|
| Site: | Diablo Canyon  |
| Issue date: | 08/07/1995 |
| From: | Stone J NRC (Affiliation Not Assigned) |
| To: | Rueger G PACIFIC GAS & ELECTRIC CO. |
| References | |
| NUDOCS 9509110204 | |
| Download: ML16342D043 (8) | |
See also: IR 05000275/1994025
Text
Hr. Gregory
M. Rueger
Pacific Gas
and Electric Company
NPG Hail Code AlOD
P.O.
Box 770000
San Francisco,
94177
SUBJECT:
REQUEST
FOR
INFORMATION REGARDING PROPOSED
CHANGE TO PRESSURIZER
SAFETY VALVES AT DIABLO CANYON NUCLEAR POWER PLANT, UNITS
1
AND 2
Dear Hr. Rueger:
The
NRC staff has
become
aware of modifications to the pressurizer
safety
valves
(PSVs)
being proposed
by Pacific
Gas
and Electric
(PG&E) (see
Inspection
Report 50-275/94-24
and
LER 94-009-01).
In addition, the
NRC staff
discussed
the issue with members of your staff on August 24,
1995.
In an
attempt to improve set point drift performance of the
PSVs, it is our
understanding
that
PG&E is considering installing redesigned
internal parts
(i.e.,
upper spring washers)
in the valves.
In the case of PSVs, extensive qualification testing of the existing valve
design
has
been
performed to assure
adequate
performance of the valves
including adequate
discharge,
stable operation,
and proper reseating for the
required operating
and accident fluid conditions.
In order for the staff to
fully understand
the modifications
and the basis for continued qualification,
the staff requests
a response
to the enclosed
questions.
Because
the
modifications are being proposed to be implemented at Diablo Canyon Unit 1,
during the upcoming outage,
the staff requests
your response
by September
30,
1995.
If you have
any questions
or wish to further discuss this issue with
the staff, please
contact
me at (301) 415-3063.
This requirement affects nine
or fewer respondents
and, therefore,
is not subject to the Office of
Management
and Budget review under P.L.96-511.
Sincerely,
ORIGINAL SIGNED BY:
James
C. Stone,
Senior Project
Manager
Project Directorate
IV-2
Division of Reactor Projects III/IV
Office of Nuclear Reactor Regulation
Docket Nos.
50-275
and 50-323
Enclosure:
Request for Additional
cc w/encl:
See next page
DOCUMENT NAME:
DCPSV.RAI
DISTRIBUTION
Docket
PUBLIC
Information
PDIV-2 Reading
JRoe
EAdensam
WBateman
DChamberlain,
RIV
RWessman
ACRS (4)
EPeyton
KPerkins,
WCFO
JDyer,
RIV
JStone
OFC
DATE
PDIV-2 LA
ElpeeyPn
9/"1 /95
NRR:EHE
9/
/95
PDIV-2
P
JStone:ye
9
/95
OFFICIAL RECORD
COPY
<< "GC <.3
9509ii0204 950807
ADQCK 05000275
6
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,t
1
September
7,
1995
Hr. Gregory H. Rueger
Pacific Gas
and Electric Company
NPG - Hail Code AlOD
P.O.
Box 770000
San Francisco,
94177
SUBJECT:
RE(VEST
FOR
INFORMATION REGARDING PROPOSED
CHANGE TO PRESSURIZER
SAFETY VALVES AT DIABLO CANYON NUCLEAR POWER PLANT, UNITS
1
AND 2
Dear Hr. Rueger:
The
NRC staff has
become
aware of modifications to the pressurizer
safety
valves
(PSVs)
being proposed
by Pacific Gas
and Electric
(PG&E) (see
Inspection
Report 50-275/94-24
and
LER 94-009-01).
In addition, the
NRC staff
discussed
the issue with members of your staff on August 24,
1995.
In an
attempt to improve set point drift performance of the
PSVs, it is our
understanding
that
PG&E is considering installing redesigned
internal parts
(i.e.,
upper spring washers)
in the valves.
In the case of PSVs,
extensive qualification testing of the existing valve
design
has
been
performed to assure
adequate
performance of the valves
including adequate
discharge,
stable operation,
and proper reseating for the
required operating
and accident fluid conditions.
In order for the staff to
fully understand
the modifications
and the basis for continued qualification,
the staff requests
a response
to the enclosed
questions.
Because
the
modifications are being proposed to be implemented at Diablo Canyon Unit 1,
during the upcoming outage,
the staff requests
your response
by September
30,
1995.
If you have
any questions
or wish to further discuss this issue with
the staff, please
contact
me at (301) 415-3063.
This requirement affects nine
or fewer respondents
and, therefore,
is not subject to the Office of
Management
and Budget review under P.L.96-511.
Sincerely,
ORIGINAL SIGNED BY:
James
C. Stone,
Senior Project
Manager
Project Directorate
IV-2
Division of Reactor Projects III/IV
Office of Nuclear Reactor Regulation
Docket Nos.
50-275
and 50-323
Enclosure:
Request for Additional
cc w/encl:
See next page
DOCUMENT NAME:
DCPSV.RAI
DISTRIBUTION
Docket
PUBLIC
Information
PDIV-2 Reading
JRoe
EAdensam
WBateman
DChamberlain,
RIV
RWessman
ACRS (4)
EPeyton
KPerkins,
WCFO
JDyer,
RIV
JStone
OFC
NAME
DATE
PDIV-2 LA
fPeeySn
9/ "1
95
PDIV-2
P
NRR:EME
JStone:
e
9
/95
9
95
OFFICIAL RECORD
COPY
r
Mr. Gregory
M. Rueger
cc w/encl:
NRC Resident
Inspector
Diablo Canyon Nuclear
Power Plant
c/o U.S. Nuclear Regulatory
Commission
P. 0.
Box 369
Avila Beach,.California
93424
Dr. Richard Ferguson,
Energy Chair
1100 11th Street,
Suite
311
Sacramento,
Cal iforni a
95814
Ms. Nancy Culver
San Luis Obispo
Mothers for Peace
P. 0.
Box 164
Pismo Beach, California
93448
Ms. Jacquelyn
C. Wheeler
P. 0.
Box 164
Pismo Beach, California
93448
Managing Editor
The Count
Tele
ram Tribune
1321 Johnson
Avenue
P. 0.
Box 112
San Luis Obispo, California
93406
Chairman
San Luis Obispo County Board of
Supervisors
Room 370
County Government
Center
San Luis Obispo, California
93408
Mr. Truman Burns
Mr. Robert Kinosian
California Public Utilities Commission
505
Van Ness,
Room 4102
San Francisco,
94102
Mr. Steve
Hsu
Radiologic Health Branch
State
Department of Health Services
Post Office Box 942732
Sacramento,
94232
Regional Administrator,
Region
IV
U.S. Nuclear Regulatory
Commission
Harris Tower
& Pavillion
611
Ryan Plaza Drive, Suite
400
Arlington, Texas
76011-8064
Mr. Peter
H. Kaufman
Deputy Attorney General
State of California
110 West
A Street,
Suite
700
San Diego, California
92101
Christopher J.
Warner,
Esq.
Pacific Gas
& Electric Company
Post Office Box 7442
San Francisco,
94120
Mr. Warren
H. Fujimoto
Vice President
and Plant Manager
Diablo Canyon Nuclear
Power Plant
P. 0.
Box 56
Avila Beach, California
93424
Diablo Canyon
Independent
Safety
Committee
ATTN:
Robert
R. Wellington,
Esq.
Legal
Counsel
857 Cass Street,
Suite
D
Monterey, California
93940
E UEST
FOR
INFORMATION REGARDING PROPOSED
DESIGN
CHANGE TO
RESSURIZER
SAFETY VALVES AT DIABLO C
0
UCL
R
0
L
UNITS I AND
Licensee
Event Report 94-009-01 for Diablo Canyon Unit I describes
a planned
modification to the Unit I and
2 pressurizer
safety valves
(PSVs).
Based
on
a
telephone
conversation
between the
NRC staff and
PG&E staff,
we understand
that this modification is to be implemented during the next refueling outage
at Unit I, currently scheduled
to begin September
30,
1995,
and during the
next Unit 2 outage.
We also understand
that the modification involves the
installation of redesigned
upper spring washers
in the
PSVs for the purpose of
reducing
PSV setpoint drift.
While the reduction of setpoint drift.is one
important consideration
in the overall performance of the
PSVs,
the
NRC staff
seeks
assurance
that the proposed
new upper spring washer design will not have
an adverse effect on the capability of the plant
PSVs in performing their
safety function.
One possible effect is the apparent
increase
in frictional
effects of the
new washer design
along the sides of the valve spring
and along
the valve stem
as the valve disk travels to its fully open position, for
required discharge.
Specifically, it appears
that the design of the
new upper
spring washers
includes
new surface
areas
where friction could occur (i.e.,
between the washer inside collar and the stem surface
and
between
the washer
outside collar and the spring coils).
There are specific regulatory
requirements
which address
certain
PSV safety issues.
The following questions
pertain to these
issues
in relation to the proposed
change of the upper spring
washer design for the plant
PSVs:
The
NRC transmitted
a safety evaluation
(SE) dated January
27,
1986,
regarding the
Item II.D.I requirements
for safety
and relief
valve testing.
The
SE documented
the staff's findings regarding,
among
other items, the qualification of the plant
PSVs.
Specifically, Crosby
model
HB-BP-86
6M6 PSVs representative
of the plant model valves were
tested
at the Electric Power Research
Institute
(EPRI) test. facility to
demonstrate
their capability to adequately
open to the full'pen
position,
develop required discharge
in a stable
manner,
and adequately
reseat
to prevent excessive
loss of reactor coolant.
These tests
were
conducted
under full temperature,
full pressure,
full flow fluid test
conditions representative
of the plant design operating
and accident
conditions.
Provide the basis,
used
by Pacific
Gas
and Electric, that
provides
assur ance that the plant
PSVs, with the
new upper spring washer
modification, continue to meet the
Item II.D.I requirements.
2.
The American Society of Mechanical
Engineers
(ASME), Boiler and Pressure
Vessel
Code,
Section III provides requirements for the design,
construction, certification and inspection of safety
components
including the
PSVs.
Provide information which assures
that the
Code requirements
continue to be met regarding the plant
PSVs with the
proposed
new upper spring washers.
Specifically, include information
which documents
the compliance with:
the
Code material quality
requirements;
the
Code design requirements;
the requirements of the
Code
N and
NV Certificate Holder for design,
construction,
and capacity
certification;
and the requirements
of the Authorized Observer (or third
party) in inspecting
and assuring
the compliance of the Certificate
Holder.
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