[Federal Register Volume 75, Number 22 (Wednesday, February 3, 2010)]
[Rules and Regulations]
[Pages 5495-5498]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2010-2283]


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NUCLEAR REGULATORY COMMISSION

10 CFR Part 50

RIN 3150-AI01
[NRC-2007-0008]


Alternate Fracture Toughness Requirements for Protection Against 
Pressurized Thermal Shock Events; Correction

AGENCY: Nuclear Regulatory Commission.

ACTION: Final rule; correction.

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SUMMARY: This document corrects a rule that appeared in the Federal 
Register on January 4, 2010 (75 FR 13), that amends the NRC's 
regulations to provide alternate fracture toughness requirements for 
protection against pressurized thermal shock (PTS) events for 
pressurized water reactor (PWR) pressure vessels. This document is 
necessary to correct formatting and typographical errors in paragraph 
(g).

DATES: The correction is effective February 3, 2010, the date the 
original rule becomes effective.

FOR FURTHER INFORMATION CONTACT: Michael T. Lesar, Chief, Rulemaking 
and Directives Branch, Office of Administration, Nuclear Regulatory 
Commission, Washington, DC 20555-0001, telephone 301-492-3663, e-mail 
[email protected].

SUPPLEMENTARY INFORMATION: In FR doc. E9-31146, published on January 4, 
2010, make the following correction:


Sec.  50.61a  [Corrected]

0
1. On page 27, paragraph (g) of Sec.  50.61a is corrected to read as 
follows:
    (g) Equations and variables used in this section.

    [GRAPHIC] [TIFF OMITTED] TR03FE10.000
    
    [GRAPHIC] [TIFF OMITTED] TR03FE10.001
    

[[Page 5496]]


[GRAPHIC] [TIFF OMITTED] TR03FE10.002

[GRAPHIC] [TIFF OMITTED] TR03FE10.003

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[GRAPHIC] [TIFF OMITTED] TR03FE10.006

where:

P [wt-&%] = phosphorus content
Mn [wt-%] = manganese content
Ni [wt-%] = nickel content
Cu [wt-%] = copper content
A = 1.140 x 10-7 for forgings
A = 1.451 x 10-7 for plates
A = 1.417 x 10-7 for welds
B = 102.3 for forgings
B = 102.5 for plates in non-Combustion Engineering manufactured 
vessels
B = 135.2 for plates in Combustion Engineering vessels
B = 155.0 for welds

[phis]te = [phis]t for [phis] >= 4.39 x 10\10\ n/cm\2\/sec
[phis]te = [phis]t x (4.39 x 10\10\/[phis])\0.2595\ for 
[phis] < 4.39 x 10\10\ n/cm\2\/sec

where:

[phis] [n/cm\2\/sec] = average neutron flux
t [sec] = time that the reactor has been in full power operation
[phis]t [n/cm\2\] = [phis] x t

f(Cue,P) = 0 for Cu <= 0.072
f(Cue,P) = [Cue-0.072]\0.668\ for Cu > 0.072 and 
P <= 0.008
f(Cue,P) = [Cue-0.072 + 1.359 x (P-0.008)]\0.668\ 
for Cu > 0.072 and P > 0.008

where:

Cue = 0 for Cu <= 0.072
Cue = MIN (Cu, maximum Cue) for Cu > 0.072
maximum Cue = 0.243 for Linde 80 welds
maximum Cue = 0.301 for all other materials

g(Cue,Ni,[phis]te) = 0.5 + (0.5 x tanh 
{[log10([phis]te) + (1.1390 x Cue)-
(0.448 x Ni)-18.120]/0.629{time} 
Equation 8: Residual (r) = measured [Delta]T30-predicted 
[Delta]T30 (by Equations 5, 6 and 7)
[GRAPHIC] [TIFF OMITTED] TR03FE10.007

Equation 10: Maximum credible heat-average residual = 2.33[sigma]/
n\0.5\


where:where:

n = number of surveillance data points (sample size) in the specific 
data set
[sigma] = standard deviation of the residuals about the model for a 
relevant material group given in Table 5.
[GRAPHIC] [TIFF OMITTED] TR03FE10.008

where:

m is the slope of a plot of all of the r values (estimated using 
Equation 8) versus the base 10 logarithm of the neutron fluence for 
each r value. The slope shall be estimated using the method of least 
squares.
se(m) is the least squares estimate of the standard-error associated 
with the estimated slope value m.
[GRAPHIC] [TIFF OMITTED] TR03FE10.009

where:

r is defined using Equation 8 and [sigma] is given in Table 5

                                         Table 1--PTS Screening Criteria
----------------------------------------------------------------------------------------------------------------
                                                            RTMAX	X limits [[deg]F] for different vessel wall
                                                                         thicknesses \6\ (TWALL)
            Product form and RTMAX	X  values            --------------------------------------------------------
                                                                             9.5 in. < TWALL    10.5 in. < TWALL
                                                          TWALL <= 9.5 in.     <= 10.5 in.        <= 11.5 in.
----------------------------------------------------------------------------------------------------------------
Axial Weld--RTMAX	AW...................................                269                230                222
Plate--RTMAX	PL........................................                356                305                293
Forging without underclad cracks--RTMAX	FO \7\.........                356                305                293
Axial Weld and Plate--RTMAX	AW + RTMAX	PL..............                538                476                445
Circumferential Weld--RTMAX	CW \8\.....................                312                277                269
Forging with underclad cracks--RTMAX	FO \9\............                246                241                239
----------------------------------------------------------------------------------------------------------------
\6\ Wall thickness is the beltline wall thickness including the clad thickness.
\7\ Forgings without underclad cracks apply to forgings for which no underclad cracks have been detected and
  that were fabricated in accordance with Regulatory Guide 1.43.
\8\ RTPTS limits contribute 1x10-8 per reactor year to the reactor vessel TWCF.

[[Page 5497]]

 
\9\ Forgings with underclad cracks apply to forgings that have detected underclad cracking or were not
  fabricated in accordance with Regulatory Guide 1.43.


               Table 2--Allowable Number of Flaws in Welds
------------------------------------------------------------------------
          Through-wall extent, TWE [in.]              Maximum number of
---------------------------------------------------   flaws per 1,000-
                                                       inches of weld
                                                        length in the
                                                      inspection volume
           TWEMIN                    TWEMAX           that are greater
                                                      than or equal to
                                                    TWEMIN and less than
                                                           TWEMAX
------------------------------------------------------------------------
0...........................  0.075...............  No Limit.
0.075.......................  0.475...............  166.70.
0.125.......................  0.475...............  90.80.
0.175.......................  0.475...............  22.82.
0.225.......................  0.475...............  8.66.
0.275.......................  0.475...............  4.01.
0.325.......................  0.475...............  3.01.
0.375.......................  0.475...............  1.49.
0.425.......................  0.475...............  1.00.
0.475.......................  Infinite............  0.00.
------------------------------------------------------------------------


        Table 3--Allowable Number of Flaws in Plates and Forgings
------------------------------------------------------------------------
        Through[dash]wall extent, TWE [in.]           Maximum number of
---------------------------------------------------    flaws per 1,000
                                                      square-inches of
                                                     inside surface area
                                                      in the inspection
                                                       volume that are
                                                       greater than or
           TWEMIN                    TWEMAX          equal to TWEMIN and
                                                      less than TWEMAX.
                                                      This flaw density
                                                      does not include
                                                     underclad cracks in
                                                          forgings
------------------------------------------------------------------------
0...........................  0.075...............  No Limit.
0.075.......................  0.375...............  8.05.
0.125.......................  0.375...............  3.15.
0.175.......................  0.375...............  0.85.
0.225.......................  0.375...............  0.29.
0.275.......................  0.375...............  0.08.
0.325.......................  0.375...............  0.01.
0.375.......................  Infinite............  0.00.
------------------------------------------------------------------------


 Table 4--Conservative Estimates for Chemical Element Weight Percentages
------------------------------------------------------------------------
                Materials                        P              Mn
------------------------------------------------------------------------
Plates..................................           0.014            1.45
Forgings................................           0.016            1.11
Welds...................................           0.019            1.63
------------------------------------------------------------------------


 Table 5--Maximum Heat-Average Residual [[deg]F] for Relevant Material Groups by Number of Available Data Points
                                            (Significance Level = 1%)
----------------------------------------------------------------------------------------------------------------
                                                                 Number of available data points
           Material group             [sigma]  -----------------------------------------------------------------
                                      [[deg]F]      3          4          5          6          7          8
----------------------------------------------------------------------------------------------------------------
Welds, for Cu > 0.072..............       26.4       35.5       30.8       27.5       25.1       23.2       21.7
Plates, for Cu > 0.072.............       21.2       28.5       24.7       22.1       20.2       18.7       17.5
Forgings, for Cu > 0.072...........       19.6       26.4       22.8       20.4       18.6       17.3       16.1
Weld, Plate or Forging, for Cu <=         18.6       25.0       21.7       19.4       17.7       16.4       15.3
 0.072.............................
----------------------------------------------------------------------------------------------------------------


 Table 6--TMAX Values for the Slope Deviation Test (Significance Level =
                                   1%)
------------------------------------------------------------------------
           Number of available data points (n)                 TMAX
------------------------------------------------------------------------
3.......................................................           31.82
4.......................................................            6.96
5.......................................................            4.54
6.......................................................            3.75
7.......................................................            3.36
8.......................................................            3.14
9.......................................................            3.00
10......................................................            2.90
11......................................................            2.82
12......................................................            2.76
13......................................................            2.72
14......................................................            2.68
15......................................................            2.65
------------------------------------------------------------------------


    Dated at Rockville, Maryland, this 29th day of January 2010.


[[Page 5498]]


    For the Nuclear Regulatory Commission.
Michael T. Lesar,
Chief, Rulemaking and Directives Branch, Division of Administrative 
Services, Office of Administration.
[FR Doc. 2010-2283 Filed 2-2-10; 8:45 am]
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