ML20136C922
| ML20136C922 | |
| Person / Time | |
|---|---|
| Site: | 05000000, Vogtle |
| Issue date: | 10/03/1984 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML082840446 | List:
|
| References | |
| FOIA-84-663 NUDOCS 8601040008 | |
| Download: ML20136C922 (3) | |
Text
w.
s 6
- s, 9 e
L ATTACHMENT Vogtle Electric Generating Plant, Units 1 and 2 Docket Nos. 50-424 and 50-425 Materials Engineering Branch Materials Application Section Fracture Prevention of Containment Pressure Boundary Our safety evaluation review assessed the ferritic materials in the Vogtle Electric Generating Plant, Units 1 and 2, containment system that consti-
[
tute the containment pressure boundary to determine if the material fracture toughness is in compliance with the requirements of General Design Criterion 51, " Fracture Prevention of Containment Pressure Boundary."
l GDC 51 requires that under operating, maintenance, testing and postulated accidentconditions,(1)theferriticmaterialsofthecontainmentpres-sure boundary behave in a nonbrittle manner and (2) the probability of
(
rapidly propagating fracture is minimized.
The Vogtle 1 and 2 contair. ment is a reinforced concrete structure, with a thin steel liner on the inside surface, which serves as a leaktight membrane.
The ferritic materials of the containment pressure boundary which were con-L sidered in our assessment are those which have been applied in the fabrica-
~
tion of the equipment hatch, personnel locks, penetrations and fluid system components including the valves required to isolate the system. These com-ponents are the parts of the containment system which are not backed by g
concrete and must sustain loads during the performance of the containment function under the conditions cited by GDC 51.
j 3
We have determined that the fracture toughness requirements contained in ASME Code editions and addenda typical of those used in the design of the
]
Vogtle 1 and 2 containment may not ensure compliance with GDC 51 for all P
areas of the containment pressure boundary. We have elected to apply in our licensing reviews of ferritic containment pressure boundary materials the criteria for Class 2 components identified in the Summer 1977 Addenda i
8601040008 851127
~
a
m.m._..
1 1.
of Section IIit'of the ASME Code. Because the fracture toughness criteria that have been applied in construction typically differ in Code classifi-cation and Code edition and addenda, we have chosen the criteria in the Sumer 1977 Addenda of Section III of the Code to provide a uniform review, consistent with the safety function of the containment pressure boundary materials. Therefore, we reviewed the materials of the components of the Vogtle 1 and 2; containment pressure boundary according to the fracture toughness requ'irements of the Summer 1977 Addenda of Section III for Class 2 cor.ponents.
Considered in our review were components of the containment system which
't are load bearing and provide a pressure boundary in the performance of the containment function under operating, maintenance, testing and postu-lated accident ccnditions as addressed in GDC 51. These components are the equipment. hatch, personnel airlocks, penetrations and elements of (7
specific containment penetrating systems.
~
Our assessment is based on the metallurgical characterization of these materials and fracture toughness data present'ed in NUREG-0577, " Potential for Low Fracture Toughness and Lamellar Tearing on PWR Steam Generator and Reactor Coolant Pump Supports," USNRC, October 1979, for coment and ASME Code Section III, Sum er 1977 Addenda, Subsection NC.
The metal b rgical characterization of these materials, with respect to their fracture toughness, was developed from a review of how these materials were fabricated and what thennal history they experienced during fabrication.
The metallurgical characterization of these materials, when correlated with the data presented in NUREG-0577 above and the Summer 1977 Addenda of the ASME Code Section III, provides the technical basis for our evaluation of compliance with the Code requirements.
Based on our review of the available fracture toughness data and materials fabrication histories, and the use of correlations between metallurgical characteristics and material fractura tcughness, we conclude, conditioned m
- /
J
]
't i
on the receipt of corfirmatory information, that the ferritic components e
in the Vogtle 1 and 2 containment pressure boundary meet the fracture
('j toughness requirements that are specified for Class 2 components by the f
1977 Addenda of Section III of the ASHE Code. Compliance with these Code fh requirements provides reasonable assurance that the Vogtle 1 and 2 reactor i
containment pressure boundary will behave in a nonbrittle manner, that the probability of rapidly propagating fracture will be minimized and that the requirements of GDC 51 are satisfied.
c I
?
k i
4:
o
,i i
if
.t s
e; i
&.y, r-i 3.
~
[
P N:
.