United States Nuclear Regulatory Commission - Protecting People and the Environment

Bulletin 71-03: Connecticut Yankee Atomic Power Company

                                                             IEB 71-03

                                 UNITED STATES
                           ATOMIC ENERGY COMMISSION
                            DIVISION OF COMPLIANCE
                                   REGION I
                               970 BROAD STREET
                           NEWARK, NEW JERSEY 07102

                                      December 10, 1971


Connecticut Yankee Atomic Power Company                      Docket No. 50-213
ATTN:  Mr. D. C. Switzer, President
P.O. Box 270
Hartford, Connecticut 06101


We recently received information from the Florida Power and Light Company of
an occurrence during preoperational testing of the Turkey Point 3 Westinghouse
pressurized water reactor that may relate to performance of the steam supply
system at your facility.  The information is as follows:

During hot functional testing of the unfueled reactor, three of four relief
valves were catastrophically ejected from two main steam line headers, to
which they were mounted.  The failed headers were 12-inch diameter, spool
pieces fabricated by the Dravo Corporation, Marietta, Ohio, from Schedule 60
(.562-inch wall thickness) A106, Grade B carbon steel pipe manufactured by
U.S. Steel, Lorain Works, Lorain, Ohio, mounted horizontally, 180 deg from
each other, on the two sides of the main steam line.  The headers were
hydrostatically tested at 1356 psig under cold conditions prior to hot
functional testing.  On one side of the main steam line, the failure occurred
in the vicinity of the heat affected zone of the weld which joins the riser to
the header and appears to be largely confined to the 12-inch header.  On the
other side of the main steam line, the failure apparently originated in a
similar manner and propagated through the pipe header causing catastrophic
damage to the header assembly.  The secondary system was at 990 psig and 545
deg F and the primary system at 2232 psig and 546.6 deg F at the time of the
header failure.  These systems had been at their respective pressures and
temperatures for nine days.  No transient conditions were reported to have
existed in these systems at the time of failure.

-                                      2 -

The failed header assemblies each consist of two valves mounted vertically in
a dead-end, 12-inch diameter pipe projecting at a 90 deg horizontal angle from
the main steam line.  The two headers are mounted at 180 deg to each other on
the opposite sides of the main steam line.  The headers were designed to meet
Section I of the ASME Code by the Bechtel Corporation.

For your reactors which are licensed to operate, it is requested that you
provide this office within ten days, in writing, as to whether headers as
described above are installed in the steam lines of your facility.

Should you have any questions concerning this matter, we will discuss them
with you.

                                   Very truly yours,

                                   James P. O'Reilly

cc:  Mr. W. Hartley, Plant Superintendent

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