ML20203C421
| ML20203C421 | |
| Person / Time | |
|---|---|
| Site: | Maine Yankee |
| Issue date: | 04/14/1986 |
| From: | Whittier G Maine Yankee |
| To: | NRC OFFICE OF ADMINISTRATION (ADM) |
| References | |
| FRN-51FR5815, REF-GTECI-A-49, REF-GTECI-RV, RTR-REGGD-01.099, RTR-REGGD-1.099, TASK-A-49, TASK-OR 7387L-HFJ, GDW-86-96, MN-86-56, NUDOCS 8604210153 | |
| Download: ML20203C421 (6) | |
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mAmE HARHEE AT0ml0POWERCORIPARSe avaug,ay,?n"e%l (207) 623-35ft R
April 14, 1986
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Office of Administration United States Nuclear Regulatory Commission
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Hashington, D. C.
20555 Attention:
Rules and Procedures Branch Division of Rules and Records
References:
(a) License No. DPR-36 (Docket No. 50-309)
(b) USNRC Letter to Distribution dated February 10,1986 on Task ME 305-4 (c) MYAPCo Letter to USNRC dated January 21, 1986 (MN-86-14)
" Response to Requirement of 10 CFR 50.61 (Pressurized Thermal Shock Rule)"
Subject:
Comments on Proposed Revision 2 to Regulatory Guide 1.99 Radiation Damage to Reactor Vessel Materials Gentlemen:
Maine Yankee Atomic Power Company is pleased to offer the following comments on the Proposed Revision 2 to Regulatory Guide 1.99, " Radiation Damage to Reactor Vessel Materials", which was issued for comment in Re~ference (b).
Before commenting in detail, we would like to comment on the application of the proposed revision to calculations of reference temperatures for comparison to the Pressurized Thermal Shock (PTS) screening criterion defined in the PTS Rule. Maine Yankee's response to the requirements of the PTS rule was provided in Reference (c). A comparison between the reference temperatures reported in Reference (c) and those calculated using the proposed revision is provided in Table I.
Maine Yankee has approximately 50*F margin to the PTS screening criterion using either approach as can be seen from inspection of Table I.
Furthermore, Maine Yankee is projected to reach the screening criterion in approximately the same year (2060 for the proposed revision versus 2054 for the PTS Rule).
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MAtNE YANKEE ATOMIC POWER COMPANY United States Nuclear Regulatory Commission Page Two Attention:
Rule and Procedures Branch HN-86-56 The reference temperatures of beltline materials calculated using the two approaches can be considerably different. This is particularly true for intermediate copper, high nickel welds. This difference is illustrated by weld seams 3-203 A,B,C which have a best estimate chemistry of 0.22 w/o copper and 0.84 w/o nickel, see Table I.
The difference does not have any overall impact on Maine Yankee's evaluation.
This is because of the less favorable chemistry and fluence factors of weld seam 9-203, the critical weld. However, these effects can have a considerable impact on other licensee's evaluation.
He are concerned that there is not an adequate basis for use of the PTS Rule's screening criterion for application with the proposed revision.
Our specific comments on the proposed revision are provided in the enclosure.
Thank you for the opportunity to comment.
Very truly yours, HAINE YANKEE ATOMIC POWER COMPANY bhAV n
G. D. Whittier, Manager Nuclear Engineering and Licensing GDH/bj p
Enclosures:
Table I and Specific Comments cc: Mr. Ahsok C. Thadani Dr. Thomas E. Murley Mr. Pat Sears Mr. Cornelius F. Holden 7387L-HFJ
M AINE YANKEE ATOMIC POWER COMPANY '
Enclosure MN-86-56 COMMENTS OF MAINE YANKEE ATOMIC POWER COMPANY ON PROPOSED REVISION 2 0F REGULATORY GUIDE 1.99
" RADIATION DAMAGE TO REACTOR VESSEL MATERIALS" GENERAL There are several instances in which licensees could be penalized for having surveillance data.
Examples are in the treatment of Initial RTNDT (Regulatory Position 1.1), delta RTNDT (Regulatory Position 2.1) and uncertainties.
The availability of surveillance data should generally result in an overall reduction in adjusted reference temperature. The regulatory position should recognize that conflicts in data can arise resulting in surveillance data being over-conservative.
The regulatory position should identify what justification must be provided to use alternates to surveillance data.
DISCUSSION (Pages 2-5)
The proposed revision states that "when there are two or more sets of surveillance data from one reactor, the scatter of delta RTNDT values about a best-fit line drawn as described in Regulatory Position 2.1 normally should be less than 28*F for welds and 17*F for base metal.
Even if the fluence range is large (two or more orders of magnitude), the scatter should not exceed twice those values". However, the proposed revision provides no guidance for instances in which a critical beltline material is included in the surveillance program of another reactor.
Add guidance to this section and Regulatory Position 2 on applications of surveillance data from another plant.
This guidance should include consideration that the beltline material in question may or may not be included in the Licensee's surveillance program. Appropriate cor, sideration of uncertainties should also be addressed.
REGULATORY POSITION 1 - SURVEILLANCE DATA NOT AVAILABLE 1.1 Adjusted Reference Temperature - Initial RTNDT (Page 6)
Regulatory Position 1.1 states that "If measured values of Initini RTNDT for the material in question are not available, generic mean values for that class of material may be used if there are sufficient test results to establish a mean and standard deviation for the class". However, the position does not give the licensee the option of using the generic data if measured values of Initial RTNDT are available. The use of the generic data in these instances is as technically defendable as the instance when no measurements are available.
In many instances, the licensee will be penalized for having plant specific measurements.
Delete the phrase, "if measured values of Initial RTNDT for the material in question are not available", from this sentence.
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MQtNE YANKEE ATOM C POWER COMPAPW
'l.11 Adjusted Reference Temperature - Delta RTNDT at Depth (Page 7)
The use of dpa-(displacements per atom) as a damage function appears to be a conservative approach to determine damage at depth. However, the mathematical simplifications made to apply dpa introduces a time dependency on the flux. reduction factor.
Furthermore, the simplified approach, in some instances, introduces additional unnecessary conservatisms.
Revise the position to allow the licensee to either apply the more exact formulation or use a plant specific dpa.
4 REGULATORY POSITION 2 - SURVEILLANCE DATA AVAILABLE 2.1 Adiusted Reference Temoerature - Marain (Paae 8)
The proposed method.for calculating the adjusted reference temperature when credible surveillance data is available requires a minimum value of sigma delta of 14*F to be used in equation 4.
- Assuming a measured value of initial RTNDT is used, the resulting margin is 28'F.
However, Maine Yankee believes that sufficient conservatisms already exist in the overall procedures to assure.
brittle fracture is avoided.
4 Revise the position to allow licensees to use surveillance data directly without additional margin.
j 2.1. Adiusted Reference Temoerature - Margin (Page 8)
The proposed method for calculating the adjusted reference temperature when credible surveillance data is available provides no basis for reducing the uncertainty in the shift (delta RTNDT) defined by equation 4 by one-half (1/2). The actual uncertainty may be dependent on how well the least-square fitting procedure fits the surveillance data.
Consider more exacting formulation for determining uncertainty in the shift.
The formulation should allow licensees to use surveillance dataadirectly without additional margin under certain conditions.
See comment above.
2.1 Adiusted Reference Temperature - Fluence Facter (Page 8)
The proposed method does not recognize alternate approaches for 1.
determining a best estimate fit of surveillance data.
In particular, approaches such as fitting multiple surveillance data with an alternate fluence factor is not addressed.
Add guidance on use of multiple surveillance data to justify alternate fluence factor.
Include determination of uncertainty in the shift (delta RTNDT) as appropriate.
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MAtNE YoNMEE ATOMIC POWER COMPANY 2.1 Adiusted Reference Temoerature - Use of Reaulatory Position 1.1 (Pace 8)
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The proposed method states that "If this procedure gives a higher value of adjusted reference temperatures than that given by using the procedures of Regulatory Position 1.1, the surveillance data should be used.
If this procedure gives a lower value, either may be used." This position is an example of penalizing the l'censee for having surveillance data.
ine regulatory positions should recognize I
that use of Regulatory Position 1.1 may be justified if it can be demonstrated that surveillance material or measurements do not adequately represent the beltline material in question.
Revise the position to allow the licensee to use Regulatory Position 1.1 even when surveillance data is available if adequate t
justification can be provided.
Identify what justification must be provided for these instances.
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TABLE I RT DATA ON JANUARY 23, 1986 AND EXPIRATION OF LICENSE FOR EifLTLINE P ES AND HELDS FOR THE MAINE YANKEE ATOMIC P0HER PLANT (1)(2)(3)
PLATE OR INITIAL FLUENCE (n/cm2)x1019(6)
JAN. 23, 1986 FLUENCE (n/cm2)x1019(6)
EOL(7)
RTPTS SCREENING HELD SEAM RTNDT (4) g(5)
(JAN. 23, 1986)
RTPTS EOL(7)
RTPTS CRITERIA (9)
Response to PTS Rule (I}
9-203
-56*F 59'F
.59 190*F 1.47 243*F(8) 300*F D-8407-2 2*F 48*F
.59 178'F 1.47 214*F 270*F 4
3-203A 8,C
-56*F 59'F
.48 132*F 1.13 167'F 270*F 0
Proposed Revision 2 to Regulatory Guide 1.99 9-203
-56*F 66*F
.59 197'F 1.47 252*F 300*F D-8407-2 2*F 34*F
.59 180*F 1.47 223*F 270*F 3-203A 8,C
-56*F 66*F
.48 174*F 1.13 223*F 270*F 0
E01ES:
(1) Critical beltline materials only. Values for Response to PTS Rule reported in Reference (c).
(2) See Table 5.1 of Reference (c) for initial chemistry data.
PTS - I + M + (-10 + 470 Cu + 350 Cu Ni) f.270] from 10CFR50.61(b)(2) is always used to calculate 0
(3) Equation 1 [RT RTPTS for Responses to PTS Rule. Proposed Revision 2 to Regulatory Guide 1.99 uses best estimate chemistry.
(4) See Tabie 5.1 of Reference (c) for source of initial RTNDT-(5) Margin from 10CFR50.61(b)(2)(ii) for Responses to PTS Rule and from Regulatory Position 1.1 for Proposed Revision.
(6) Fluence values are calculated from the following equations based on a 751 availability factor.
(a) Plates and circumferential welds. F(x 10 9n/cm2) = 0.588 + 0.0388 (YEAR - 1985).
1 (b) Axial (longitudinal) welds - 10* from flats.
F(x 1019n/cm2), o,475 + 0.0288 (YEAR - 1985).
(7) Expiration of License - 10/21/2008.
(8) Critical weld 203. Screening criterion (300F) is reached in 2054 for PTS Rule and 2060 for the Proposed Revision.
(9' Screening criteria from 10CFR50.61(b)(2).
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