[Federal Register Volume 65, Number 178 (Wednesday, September 13, 2000)]
[Notices]
[Pages 55306-55307]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 00-23526]


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NUCLEAR REGULATORY COMMISSION

[Docket No. 50-412]


Firstenergy Nuclear Operating Company, (Beaver Valley Power 
Station, Unit 2); Exemption

I

    The FirstEnergy Nuclear Operating Company (FENOC/the licensee) is 
the holder of Facility Operating License No. NPF-73 that authorizes 
operation of the Beaver Valley Power Station, Unit 2. The license 
provides, among other things, that the licensee is subject to all 
rules, regulations, and orders of the U.S. Nuclear Regulatory 
Commission (NRC, the Commission) now or hereafter in effect.
    The facility consists of a pressurized water reactor located in 
Shippingport, Beaver County, Pennsylvania.

II

    Title 10 of the Code of Federal Regulations (10 CFR) Part 50, 
Sec. 50.60(a), requires that ``all light-water nuclear power reactors * 
* * must meet the fracture toughness and material surveillance program 
requirements for the reactor coolant pressure boundary set forth in 
appendices G and H to this part.'' Appendix G to 10 CFR Part 50, 
requires that pressure-temperature (P/T) limits be established for 
reactor pressure vessels (RPVs) during normal operating and hydrostatic 
or leak rate testing conditions. Specifically, this regulation states 
that ``[t]he appropriate requirements on * * * the pressure-temperature 
limits and the minimum permissible temperature must be met for all 
conditions.'' Additionally, it specifies that the requirements for 
these limits are the American Society of Mechanical Engineers (ASME) 
Code, Section XI, Appendix G, Limits. This section of the ASME Code in 
turn specifies that RPV P/T limits be developed using the 
KIa fracture toughness curve of ASME Section XI, Appendix G, 
Figure G-2210-1, as the lower bound for fracture toughness.
    Pressurized water reactor licensees have installed low temperature 
overpressure protection (LTOP) systems in order to protect the reactor 
coolant pressure boundary (RCPB) from being operated outside of the 
boundaries established by the P/T limit curves and to provide pressure 
relief of the RCPB during low temperature overpressurization events. 
The licensee is required by the Beaver Valley Unit 2 Technical 
Specifications (TSs) to update and submit the changes to its LTOP 
setpoints whenever the licensee is requesting approval for amendments 
to the P/T limit curves in the Beaver Valley Unit 2 TSs.
    In order to address provisions of amendments to the TS P/T limits 
and LTOP curves, the licensee requested in its submittal dated June 17, 
1999, that the staff exempt Beaver Valley Unit 2 from application of 
specific requirements of 10 CFR Part 50, Sec. 50.60(a), and 10 CFR Part 
50, appendix G, and substitute the use of ASME Code Case N-640. It 
should be noted that, as a result of ASME Code committee action, the 
original designation for this Code Case (N-626) was changed to N-640. 
Therefore, Code Case N-640 will be discussed below rather than Code 
Case N-626, which is the designation referenced in Attachments C and D 
of the submittal. Code Case N-640 is an alternate reference for 
fracture toughness for reactor vessel materials for use in determining 
the P/T limits.
    The proposed action is in accordance with the licensee's 
application for exemption contained in a submittal dated June 17, 1999, 
and is needed to support the TS amendment that is contained in the same 
submittal. The proposed amendment will revise the P/T limits of TS 3/
4.4.9 for Beaver Valley Unit 2 related to the heatup, cooldown, and 
inservice test limitations for the reactor coolant system (RCS) to 15 
Effective Full Power Years (EFPYs). It will also revise the section of 
the TSs that relates to the overpressure protection system (OPPS) to 
reflect the revised P/T limits of the reactor vessels.

Code Case N-640 (formerly Code Case N-626)

    The licensee has proposed an exemption to allow the use of ASME 
Code Case N-640 in conjunction with ASME Section XI, 10 CFR 50.60(a), 
and 10 CFR Part 50, appendix G.
    The proposed amendment to revise the P/T limits for Beaver Valley 
Unit 2, relies, in part, on the requested exemption. In accordance with 
Code Case N-640, these revised P/T limits have been developed using the 
KKIc fracture toughness curve shown in ASME Section XI, 
Appendix A, Figure A-2200-1, in lieu of the KKIa fracture 
toughness curve of ASME Section XI, Appendix G, Figure G-2210-1, as the 
lower bound for fracture toughness. The other margins involved with the 
ASME Section XI, Appendix G, process of determining P/T limit curves 
remain unchanged.
    Use of the KIC curve in determining the lower bound 
fracture toughness in the development of the P/T operating limits curve 
is more technically correct than the KIa curve. 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 use of the initial 
conservatism of the KIa curve when the curve was codified in 
1974 was justified. This initial conservatism was necessary due to the 
limited knowledge of RPV materials. Since 1974, however, additional 
knowledge has been gained about RPV materials, which demonstrates that 
the lower bound on fracture toughness provided by the KIa 
curve is well beyond the margin of safety required to protect the 
public health and safety from potential RPV failure. In addition, P/T 
curves 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. Current OPPS 
setpoints produce operational constraints by limiting the P/T range 
available to the operator for heatup or cooldown of the plant. The 
operating window through which the operator heats up and cools down the 
RCS is established by the difference between the maximum allowable 
pressure determined by Appendix G of ASME Section XI and the minimum 
required pressure for the reactor coolant pump (RCP) seals adjusted for 
OPPS overshoot and instrument uncertainties. The operating window 
becomes more restrictive with continued reactor vessel service.
    Since the RCS P/T operating window is defined by the P/T operating 
and test limit curves developed in accordance with the ASME Section XI, 
Appendix G, procedure, continued operation of Beaver Valley Unit 2 with 
these P/T curves without the relief provided by ASME Code Case N-640 
would unnecessarily restrict the P/T operating window, especially at 
low temperature conditions. Reducing this operating window could 
potentially have an adverse safety impact by increasing the possibility 
of inadvertent OPPS actuation due to pressure surges

[[Page 55307]]

associated with normal plant evolutions such as RCP start and swapping 
operating charging pumps with the RCS in a water-solid condition.
    Additionally, the impact on the P/T limits and OPPS setpoints has 
been evaluated for an increased service period to 15 EFPYs based on 
ASME Section XI, Appendix G, requirements. The results indicate that 
OPPS would significantly restrict the ability to perform plant heatup 
and cooldown, create an unnecessary burden to plant operations, and 
challenge control of plant evolutions required with OPPS enabled. 
Implementation of the proposed P-T curves, as allowed by ASME Code Case 
N-640, does not significantly reduce the margin of safety. Thus, 
pursuant to 10 CFR 50.12(a)(2)(ii), the underlying purpose of the 
regulation 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 concurs that this increased knowledge permits 
relaxation of the ASME Section XI, Appendix G, requirements by 
application of ASME Code Case N-640, while maintaining, pursuant to 10 
CFR50.12(a)(2)(ii), the underlying purpose of the ASME Code and 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. Special circumstances are 
present whenever, according to 10 CFR 50.12(a)(2)(ii), ``Application of 
the regulation in the particular circumstances would not serve the 
underlying purpose of the rule or is not necessary to achieve the 
underlying purpose of the rule * * *.''
    The underlying purpose of 10 CFR part 50, section 50.60(a), and 10 
CFR part 50, appendix G, is to protect the integrity of the reactor 
coolant pressure boundary in nuclear power plants. This is accomplished 
through these regulations that, in part, specify fracture toughness 
requirements for ferritic materials of the reactor coolant pressure 
boundary. The NRC staff accepts the licensee's determination that an 
exemption would be required to approve the use of Code Case N-640.
    The NRC staff examined the licensee's rationale to support the 
exemption request. Based upon a consideration of the conservatism that 
is explicitly incorporated into the methodologies of 10 CFR part 50, 
Appendix G; ASME Section XI, appendix G; and Regulatory Guide 1.99, 
Revision 2, the NRC staff finds that the application of Code Case N-640 
will provide results which are sufficiently conservative to ensure the 
integrity of the reactor coolant pressure boundary and, thus, meet the 
underlying intent of 10 CFR part 50, section 50.60(a), and 10 CFR part 
50, appendix G. This is also consistent with determinations that the 
NRC staff has reached for other licensees under similar conditions, and 
based on the same considerations. Therefore, the NRC staff finds that 
special circumstances set forth in 10 CFR 50.12(a)(2)(ii) are present 
and that the methodology of Code Case N-640 may be used to revise the 
P/T limits and the LTOP setpoints for the Beaver Valley Unit 2 RCS.

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 FENOC an 
exemption from the requirements of 10 CFR part 50, section 50.60(a), 
and 10 CFR part 50, appendix G, for the Beaver Valley Unit 2 reactor 
coolant system.
    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 50722).
    This exemption is effective upon issuance.

    Dated at Rockville, Maryland, this 6 day of September 2000.

    For the Nuclear Regulatory Commission.
John A. Zwolinski,
Director, Division of Licensing Project Management, Office of Nuclear 
Reactor Regulation.
[FR Doc. 00-23526 Filed 9-12-00; 8:45 am]
BILLING CODE 7590-01-U