ML12145A013

Rev 1, Effects of Residual Elements on Predicted Radiation Damage to Reactor Vessel Materials

ML12145A013
Person / Time
Issue date:	04/30/1977
From:	NRC/OSD
To:
Kirk M
References
RG-1.099, Rev 1
Download: ML12145A013 (7)

Text

Retype of Next Page (1.99-3) Due to Text Illegibility C. REGULATORY POSITION (3) The expression for A is given in terms of fluence as measured by units of n/cm² (E > I MeV)

1. When credible surveillance data from the reactor however, the expression may be used in terms of in question are not available, prediction of fluence as measured by units of neutron damage fluence, 2

neutron radiation damage to the beltline of reactor provided the constant 1019 n/cm (E > l vessels of light water reactors should be based on the MeV) is changed to the corresponding value of following procedures. neutron damage fluence.

a. Reference temperature should be adjusted as (4) Application of these procedures to a function of fluence and residual element content in materials having chemical content beyond that accordance with the following expression, within the represented by the current data base should be limits below and in paragraph l.c. justified by submittal of data.

A = [40 + 1000(% Cu - 0.08) 2. When credible surveillance data from the reactor

+ 5000 (% P -0.008)] [f/1019]1/2 in question become available, they may be used to represent the adjusted reference temperature and the where Charpy upper-shelf energy of the beltline materials at the fluence received by the surveillance specimens.

A = predicted adjustment of reference temperature, °F. a. The adjusted reference temperature of the beltline materials at other fluences may be predicted 2

f = fluence, n/cm (E>1 MeV). by:

(1) extrapolation to higher or lower fluences

% Cu = weight percent of copper. from credible surveillance data following the slope of If % Cu < 0.08. use 0.08. the family of lines in Figure 1 or

% P = weight percent of phosphorus . (2) a straight-line interpolation between credible If % P < 0.008. use 0.008. data on a logarithmic plot.

b. To predict the decrease in upper-shelf energy If the value of A obtained by the above expression of the beltline materials at fluences other than those exceeds that given by the curve labeled "Upper Limit" in received by the surveillance specimens, procedures Figure I, the "Upper Limit" curve should be used. If % similar to those given in paragraph 2.a may be followed Cu is unknown, the "Upper Limit" curve should be used. using Figure 2.

3. For new plants, the reactor vessel beltline materials should have the content of residual elements such as copper, phosphorus, sulfur, and vanadium controlled to low levels. The levels should be such that the predicted adjusted reference temperature at the 1/4 T

b. Charpy upper-shelf energy should be as- position in the vessel wall at end of life is less than sumed to decrease as a function of fluence and copper 200°F.

content as indicated in Figure 2. within the limits listed in paragraph 1.c. Interpolation is permitted. D. IMPLEMENTATION The purpose of this section is to provide information

c. Application of the foregoing procedures to applicants and licensees regarding the NRC should be subject to the following limitations:

staffs plans for utilizing this regulatory guide (1) The procedures apply to those grades of This guide reflects current regulatory practice.

SA-302, 336, 533, and 508 steels having minimum Therefore, except in those cases in which the applicant specified yield strengths of 50,000 psi and under and proposes an acceptable alternative method for to their welds and heat-affected zones. complying with specified portions of the Commission's regulations, the positions described in this (2) The procedures are valid for a nominal guide will be used by the NRC staff as follows:

irradiation temperature of 550°F. Irradiation below 525°F should be considered to produce greater

1. The method described in regulatory positions C.1 damage and irradiation above 575°F may be considered and C.2 of this guide will be used in evaluating all to produce less damage. The correction factor used predictions of radiation damage called for in Appendices should be justified.

G and H to 10 CFR Part 50 submitted on or 1.99-3