[Federal Register Volume 65, Number 210 (Monday, October 30, 2000)]
[Notices]
[Pages 64723-64724]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 00-27807]


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NUCLEAR REGULATORY COMMISSION

[Docket Nos. 50-250 and 50-251]


In the Matter of Florida Power and Light Company (Turkey Point 
Plant, Units 3 and 4); Exemption

I

    Florida Power and Light Company (FPL, the licensee) is the holder 
of Facility Operating License Nos. DPR-31 and DPR-41 that authorize 
operation of the Turkey Point Plant, Units 3 and 4, respectively. The 
licenses provide, among other things, that the facilities are subject 
to all rules, regulations, and orders of the U.S. Nuclear Regulatory 
Commission (the Commission/NRC) now or hereafter in effect.
    The facilities consist of pressurized water reactors located in 
Dade County, Florida.

II

    Title 10 of the Code of Federal Regulations (10 CFR) Part 50, 
Appendix G requires that pressure-temperature (P/T) limits be 
established for reactor pressure vessels (RPVs) during normal operating 
and hydrostatic pressure or leak testing conditions. Specifically, 10 
CFR Part 50, Appendix G states that ``The appropriate requirements on 
both the pressure-temperature limits and the minimum permissible 
temperature must be met for all conditions.'' Appendix G of 10 CFR Part 
50 specifies that the requirements for these limits are the American 
Society of Mechanical Engineers (ASME) Code, Section XI, Appendix G 
Limits.
    To address the provisions of proposed license amendments to the 
technical specification (TS) P/T limits, low temperature overpressure 
protection (LTOP) system setpoints and LTOP system effective 
temperature (Tenable), the licensee requested in its 
submittal dated July 7, 2000, as supplemented October 4, 2000, that the 
staff exempt Turkey Point Units 3 and 4 from application of specific 
requirements of 10 CFR Part 50, Section 50.60(a) and Appendix G, and 
substitute use of ASME Code Cases N-588 and N-641. Code Case N-588 
permits the use of circumferentially-oriented flaws in circumferential 
welds for development of P/T limits. Code Case N-641 permits the use of 
an alternate reference fracture toughness (KIC fracture 
toughness curve instead of KIa fracture toughness curve) for 
reactor vessel materials in determining the P/T limits, LTOP setpoints 
and Tenable. Since the KIC fracture toughness 
curve shown in ASME Section XI, Appendix A, Figure A-2200-1, provides 
greater allowable fracture toughness than the corresponding 
KIa fracture toughness curve of ASME Section XI, Appendix G, 
Figure G-2210-1 (the KIa fracture toughness curve), using 
Code Case N-641 for establishing the P/T limits, LTOP setpoints and 
Tenable would be less conservative than the methodology 
currently endorsed by 10 CFR Part 50, Appendix G and, therefore, an 
exemption to apply the Code Case would be required by 10 CFR 50.60. It 
should be noted that although the use of the KIC fracture 
toughness curve in Code Case N-641 was recently incorporated into the 
Appendix G to Section XI of the ASME Code, an exemption is still needed 
because the proposed P/T limits, LTOP setpoints and Tenable 
(excluding Code Case N-641) are based on the 1996 edition (and 1997 
addenda) of the ASME Code. The licensee uses the Westinghouse version 
of LTOP which is called Cold Overpressure Mitigation System.
    The proposed license amendments will revise both the P/T limits of 
TS 3/

[[Page 64724]]

4.4.9.1 related to the heatup and cooldown of the reactor coolant 
system (RCS), and the LTOP setpoints and Tenable of TS 3/
4.4.9.3, for operation to 32 effective full power years (EFPY).

Code Case N-588

    The licensee has proposed an exemption to allow use of ASME Code 
Case N-588 in conjunction with ASME Section XI, 10 CFR 50.60(a) and 10 
CFR Part 50, Appendix G, to determine P/T limits for Turkey Point Units 
3 and 4.
    The proposed license amendments to revise the P/T limits for Turkey 
Point Units 3 and 4 rely, in part, on the requested exemption. These 
revised P/T limits have been developed using postulated flaws in the 
circumferential orientation for the circumferential welds in the Turkey 
Point RPVs, in lieu of postulating axial flaws in the circumferential 
welds.
    The use of circumferential flaws in circumferential welds is more 
appropriate than the use of axial flaws in circumferential welds. Since 
the flaws postulated in the development of P/T limits have a through-
wall depth of one-quarter of the vessel wall thickness (1.94 inches for 
the Turkey Point RPVs), the length of the postulated flaw, six times 
the depth, is more than 11 inches. For the circumferential welds in the 
Turkey Point RPVs, an axial flaw of this length centered at the weld 
would place the tips of the postulated flaw within the adjacent base 
metal above and below the weld. Therefore, the only way to maintain a 
flaw within the circumferential weld metal is to postulate a 
circumferential flaw within the weld, as accomplished using Code Case 
N-588. Note that for the base metals adjacent to the circumferential 
welds, axial flaws are, and continue to be, postulated for the 
development of P/T limits.

Code Case N-641

    The licensee has proposed an exemption to allow use of ASME Code 
Case N-641 in conjunction with ASME Section XI, 10 CFR 50.60(a) and 10 
CFR Part 50, Appendix G, to determine LTOP system effective 
temperature, Tenable.
    The proposed license amendments to revise Tenable for 
Turkey Point Units 3 and 4 rely, in part, on the requested exemption. 
The revised Tenable has been developed using the 
KIc fracture toughness curve, in lieu of the KIa 
fracture toughness curve, as the lower bound for fracture toughness of 
the reactor pressure vessel materials.
    Use of the KIc curve in determining the lower bound 
fracture toughness of RPV steels is more technically correct than use 
of the KIa curve since the rate of loading during a heatup 
or cooldown is slow and is more representative of a static condition 
than a dynamic condition. The KIc curve appropriately 
implements the use of static initiation fracture toughness behavior to 
evaluate the controlled heatup and cooldown process of a reactor 
vessel. The staff has required use of the conservatism of the 
KIa curve since 1974, when the curve was adopted by the ASME 
Code. This conservatism was initially necessary due to the limited 
knowledge of the fracture toughness of RPV materials at that time. 
Since 1974, additional knowledge has been gained about RPV materials 
which demonstrates that the lower bound on fracture toughness provided 
by the KIa curve greatly exceeds the margin of safety 
required to protect the public health and safety from potential RPV 
failure. In addition, P/T curves, LTOP setpoints and Tenable 
based on the KIc curve will enhance overall plant safety by 
opening the P/T operating window, with the greatest safety benefit in 
the region of low-temperature operations.
    Since an unnecessarily reduced P/T operating window can reduce 
operator flexibility without just basis, implementation of the proposed 
P/T curves, LTOP setpoints and Tenable as allowed by ASME 
Code Cases N-588 and N-641 may result in enhanced safety during 
critical plant operational periods, specifically heatup and cooldown 
conditions. Thus, pursuant to 10 CFR 50.12(a)(2)(ii), the underlying 
purpose of 10 CFR 50.60 and Appendix G to 10 CFR Part 50 will continue 
to be served.
    In summary, the ASME Section XI, Appendix G, procedure was 
conservatively developed based on the level of knowledge existing in 
1974 concerning RPV materials and the estimated effects of operation. 
Since 1974, the level of knowledge about these topics has been greatly 
expanded. The NRC staff has determined that this increased knowledge 
permits relaxation of the ASME Section XI, Appendix G requirements by 
application of ASME Code Cases N-588 and N-641, while maintaining, 
pursuant to 10 CFR 50.12(a)(2)(ii), the underlying purpose of the NRC 
regulations to ensure an acceptable margin of safety.

III

    Pursuant to 10 CFR 50.12, the Commission may, upon application by 
any interested person or upon its own initiative, grant exemptions from 
the requirements of 10 CFR Part 50, when (1) the exemptions are 
authorized by law, will not present an undue risk to public health or 
safety, and are consistent with the common defense and security; and 
(2) when special circumstances are present.
    The staff has determined that an exemption would be required to 
approve the use of Code Cases N-588 and N-641. The staff examined the 
licensee's rationale to support the exemption request and concurred 
that the use of the Code cases would meet the underlying purpose of 
these regulations. Based upon a consideration of the conservatism that 
is explicitly incorporated into the methodologies of 10 CFR Part 50, 
Appendix G, Appendix G of the Code, and Regulatory Guide 1.99, Revision 
2, the staff concludes that application of the Code cases as described 
would provide an adequate margin of safety against brittle failure of 
the RPV. This conclusion is also consistent with the determinations 
that the staff has reached for other licensees under similar conditions 
based on the same considerations. Therefore, the staff concludes that 
requesting exemption under the special circumstances of 10 CFR 
50.12(a)(2)(ii) is appropriate and that the methodologies of Code Cases 
N-588 and N-641 may be used to revise the P/T limits, LTOP setpoints 
and Tenable for Turkey Point Units 3 and 4.

IV

    Accordingly, the Commission has determined that, pursuant to 10 CFR 
50.12(a), the exemption is authorized by law, will not endanger life or 
property or common defense and security, and is, otherwise, in the 
public interest. Therefore, the Commission hereby grants Florida Power 
and Light Company exemption from the requirements of 10 CFR Part 50, 
Section 50.60(a) and 10 CFR Part 50, Appendix G, for Turkey Point Units 
3 and 4.
    Pursuant to 10 CFR 51.32, the Commission has determined that the 
granting of this exemption will not result in any significant effect on 
the quality of the human environment (65 FR 63265).
    This exemption is effective upon issuance.

    Dated at Rockville, Maryland, this 24th day of October 2000.

    For the Nuclear Regulatory Commission.
John A. Zwolinski,
Director, Division of Licensing Project Management, Office of Nuclear 
Reactor Regulation.
[FR Doc. 00-27807 Filed 10-27-00; 8:45 am]
BILLING CODE 7590-01-P