[Federal Register Volume 66, Number 244 (Wednesday, December 19, 2001)]
[Notices]
[Pages 65521-65522]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 01-31216]



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NUCLEAR REGULATORY COMMISSION

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


Florida Power and Light Company Turkey Point Plant, Units 3 and 
4; Exemption

1.0 Background

    The Florida Power and Light Company (the licensee) is the holder of 
Facility Operating License Nos. DPR-31 and DPR-41, which authorize 
operation of the Turkey Point Plant, Units 3 and 4. The licenses 
provide, among other things, that the facilities are 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 two pressurized water reactors located in 
Miami-Dade County in Florida.

2.0 Request/Action

    By letter dated October 23, 2000, Florida Power and Light, the 
licensee for Turkey Point Plant, requested, among other things, an 
exemption from certain requirements of 10 CFR 50.44; 10 CFR part 50, 
Appendix A, General Design Criterion 41, 42, and 43; and 10 CFR part 
50, Appendix E, section VI; related to the hydrogen control system 
(i.e., recombiners, hydrogen monitors, and post-accident containment 
vent system). The proposed exemption would remove the above 
requirements from the Turkey Point Plant design basis. The staff has 
reviewed the information provided and concludes that the requested 
exemption for the hydrogen recombiners and the post-accident 
containment vent system are justified. The staff will act on the 
exemption request for the containment hydrogen monitors, the requested 
modification to the revised Confirmatory Order issued on October 5, 
2000, and the revision to the Technical Specifications related to the 
post-accident containment vent system and the hydrogen monitors by 
separate correspondence.
    The post-accident containment vent system is provided to facilitate 
controlled venting through adding air (Service Air backed by Instrument 
Air) to the reactor containment and venting air from the containment to 
effectively maintain hydrogen concentration below 4.0 volume percent. 
Regulatory requirements for the hydrogen control system are specified 
in 10 CFR 50.44 and 10 CFR part 50, Appendix A, (General Design 
Criteria 41, 42, and 43). Additional staff guidance is provided in 
Regulatory Guide (RG) 1.7. Staff review and acceptance criteria are 
specified in Section 6.2.5 of the Standard Review Plan.

3.0 Discussion

    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.
    For this exemption, these special circumstances include 
consideration that the quantity of hydrogen prescribed by 10 CFR 
50.44(d) and RG 1.7 which necessitated the need for hydrogen 
recombiners and the post-accident containment vent system would be 
bounded by the hydrogen generated during a severe accident. As shown in 
the attached safety evaluation, the staff has found that the relative 
importance of hydrogen combustion for large, dry containments with 
respect to containment failure is quite low. This finding supports the 
argument that the hydrogen recombiners are not risk significant from a 
containment integrity perspective and that the risk associated with 
hydrogen combustion is not from design basis accidents but from severe 
accidents. Studies have shown that the majority of risk to the public 
is from accident sequences that lead to containment failure or bypass, 
and that the contribution to risk from accident sequences involving 
hydrogen combustion is actually quite small for large, dry containments 
such as Turkey Point's. This is true despite the fact that the hydrogen 
produced in these events is substantially larger than the hydrogen 
production postulated by 10 CFR 50.44(d) and RG 1.7. Hydrogen 
combustion sequences that could lead to early containment failure 
typically involve up to 75 percent core metal-water reaction. Hydrogen 
combustion sequences that could lead to late containment failure 
involve additional sources of hydrogen due to the interaction of corium 
and the concrete basemat after vessel breach. Although the recombiners 
and the post-accident containment vent system are effective in 
maintaining the RG 1.7 hydrogen concentration below the lower 
flammability limit of 4.0 volume percent (for a design basis loss-of-
coolant accident (LOCA)), they are overwhelmed by the larger quantities 
of hydrogen associated with severe accidents that would typically be 
released over a much shorter time period (e.g., 2 hours). However, 
NUREG/CR-4551 states that hydrogen combustion in the period before 
containment failure is considered to present no threat to large, dry 
containments. Table A.4-5 of NUREG/CR-4551 shows that the contribution 
of hydrogen combustion to late containment failure is also very small. 
Therefore, the relative importance of hydrogen combustion for large, 
dry containments with respect to containment failure has been shown to 
be quite low.
    The recombiners can, however, prevent a subsequent hydrogen burn, 
if needed, due to radiolytic decomposition of water and corrosion in 
the long term. Analysis performed in accordance with the methodology of 
RG 1.7 shows that the hydrogen concentration will not reach 4.0 volume 
percent for 15 days after initiation of a design basis LOCA. 
Additionally, as described in the attached safety evaluation, hydrogen 
concentrations on the order of 6.0 volume percent or less are bounded 
by hydrogen generated during a severe accident and would not be a 
threat to containment integrity since there is ample time between burns 
to reduce elevated containment temperatures using the installed 
containment heat removal systems. The Turkey Point Individual Plant 
Examination (IPE) concluded that containment survival is almost certain 
following hydrogen combustion when the Reactor Building Cooling Units 
and the Reactor Building Spray System are operating.
    The underlying purpose of 10 CFR 50.44 is to show that, following a 
LOCA, an uncontrolled hydrogen-oxygen recombination would not take 
place, or that the plant could withstand the consequences of 
uncontrolled hydrogen-oxygen recombination without loss of safety 
function. Based on the analysis, which includes the staff's evaluation 
of the risk from hydrogen combustion, resolution of Generic Issue 121, 
``Hydrogen Control for PWR [pressurized-water reactor] Dry 
Containments,'' and the Turkey Point IPE, the plant could withstand the 
consequences of uncontrolled hydrogen-oxygen recombination without loss 
of safety function and without credit for the hydrogen recombiners for 
not only the design basis case, but the more limiting severe accident 
with up to 100 percent metal-water reaction. Therefore, the 
requirements for hydrogen recombiners as part of the Turkey Point 
design basis are unnecessary and their removal from the design basis is 
justified. Additionally, elimination of the hydrogen recombiners from 
the Emergency Operating Procedures (EOPs)

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would simplify operator actions in the event of an accident and, 
therefore, would be a safety benefit.
    The staff examined the licensee's rationale that supports the 
exemption request and concluded that the exemption requested for the 
recombiners and the post-accident containment vent system is justified 
as stated in the supporting safety evaluation. Additionally, 
elimination of the hydrogen recombiners and the post-accident 
containment vent system from the EOPs would be a simplification and a 
safety benefit. Consequently, pursuant to 10 CFR 50.12(a)(2)(ii), 
application of the regulation is not necessary to achieve the 
underlying purpose of the rule.
    The safety evaluation may be examined, and/or copied for a fee at 
the NRC's Public Document Room, located at One White Flint North, 11555 
Rockville Pike (first floor), Rockville, Maryland. Publicly available 
records will be accessible electronically from the ADAMS Public Library 
component on the NRC Web site, http://www.nrc.gov (the Public Reading 
Room).

4.0 Conclusion

    Accordingly, the Commission has determined that, pursuant to 10 CFR 
50.12(a), the exemption pertaining to the recombiners and the post-
accident containment vent system is authorized by law, will not present 
an undue risk to the public health and safety, and is consistent with 
the common defense and security. Also, pursuant to 10 CFR 
50.12(a)(2)(ii), special circumstances are present. Therefore, the 
Commission hereby grants Florida Power and Light Company an exemption 
from the requirements for the recombiners and the post-accident 
containment vent system as stated in 10 CFR 50.44 and 10 CFR part 50, 
Appendix A, General Design Criteria 41, 42 and 43 for the Turkey Point 
Plant, Units 3 and 4.
    Pursuant to 10 CFR 51.32, the Commission has determined that the 
granting of this exemption will not have a significant effect on the 
quality of the human environment (66 FR 59266).
    This exemption is effective upon issuance.

    Dated at Rockville, Maryland, this 12th day of December, 2001.

    For the Nuclear Regulatory Commission.
John A. Zwolinski,
Director, Division of Licensing Project Management, Office of Nuclear 
Reactor Regulations.
[FR Doc. 01-31216 Filed 12-18-01; 8:45 am]
BILLING CODE 7590-01-P