[Federal Register Volume 85, Number 197 (Friday, October 9, 2020)]
[Notices]
[Pages 64175-64178]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2020-22371]


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NUCLEAR REGULATORY COMMISSION

[Docket Nos. 50-237 and 50-249; NRC-2020-0223]


Exelon Generation Company, LLC; Dresden Nuclear Power Station, 
Units 2 and 3

AGENCY: Nuclear Regulatory Commission.

ACTION: Exemption; issuance.

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SUMMARY: The U.S. Nuclear Regulatory Commission (NRC) has issued an 
exemption from regulatory requirements for Dresden Nuclear Power 
Station, Units 2 and 3, in response to a October 21, 2019, request from 
Exelon Generation Company, LLC in order to permit exclusion of main 
steam isolation valve (MSIV) leakage from the overall integrated leak 
rate Type A test measurement, and MSIV pathway leakage contributions 
from the combined leakage rate of all penetrations and valves subject 
to Type B and Type C tests.

DATES: The exemption was issued on October 5, 2020.

ADDRESSES: Please refer to Docket ID NRC-2020-0223 when contacting the 
NRC about the availability of information regarding this document. You 
may obtain publicly available information related to this document 
using any of the following methods:
     Federal Rulemaking Website: Go to https://www.regulations.gov and search for Docket ID NRC-2020-0223. Address 
questions about Docket IDs in Regulations.gov to Jennifer Borges; 
telephone: 301-287-9127; email: [email protected]. For technical 
questions, contact the individual listed in the FOR FURTHER INFORMATION 
CONTACT section of this document.
     NRC's Agencywide Documents Access and Management System 
(ADAMS): You may obtain publicly available documents online in the 
ADAMS Public Documents collection at https://www.nrc.gov/reading-rm/adams.html. To begin the search, select ``Begin Web-based ADAMS 
Search.'' For problems with ADAMS, please contact the NRC's Public 
Document Room reference staff at 1-800-397-4209, 301-415-4737, or by 
email to [email protected]. The ADAMS accession number for each 
document referenced (if it is available in ADAMS) is provided the first 
time that it is mentioned in this document.

FOR FURTHER INFORMATION CONTACT: Russell S. Haskell, Office of Nuclear 
Reactor Regulation, U.S. Nuclear Regulatory Commission, Washington, DC 
20555-0001; telephone: 301-415-1129, email: [email protected].

SUPPLEMENTARY INFORMATION: The text of the exemption is attached.

    Dated: October 5, 2020.

    For the Nuclear Regulatory Commission.
Russell S. Haskell,
Project Manager, Plant Licensing Branch III, Division of Operating 
Reactor Licensing, Office of Nuclear Reactor Regulation.

Attachment--Exemption

NUCLEAR REGULATORY COMMISSION

Docket Nos. 50-237 and 50-249

Exelon Generation Company, LLC, Dresden Nuclear Power Station, Units 2 
and 3

Exemption

I. Background

    Exelon Generation Company, LLC (EGC, the licensee) is the holder of 
Facility Operating License Nos. DPR-19 and DPR-25, which authorize 
operation of the Dresden Nuclear Power Station, Units 2 and 3 (DNPS). 
The licenses provide, among other things, that the facilities are 
subject to the rules, regulations, and orders of the U.S. Nuclear 
Regulatory Commission (NRC, the Commission) now or hereafter in effect. 
The facilities each consist of a boiling, light-water reactor located 
in Grundy County, Illinois.

II. Request/Action

    In its letter dated October 21, 2019, as supplemented by letters 
dated May 6, 2020, and August 24, 2020 (Agencywide Documents Access and 
Management System (ADAMS) Accession Nos. ML19294A304, ML20127H891, and 
ML20237F317, respectively), EGC requested a permanent exemption from 
the Part 50 of Title 10 of the Code of Federal Regulations (10 CFR), 
Appendix J, Option B, Section III.A requirements in order to permit 
exclusion of main steam isolation valve (MSIV) leakage from the overall 
integrated leak rate Type A test measurement, and from Option B, 
Section III.B, requirements to permit exclusion of the MSIV pathway 
leakage contributions from the combined leakage rate of all 
penetrations and valves subject to Type B and Type C tests. EGC also 
requested a revision to Technical Specification (TS) 3.6.1.3, ``Primary 
Containment Isolation Valves (PCIVs),'' Surveillance Requirement (SR) 
3.6.1.3.10, that would revise the single and combined MSIV leakage rate 
limits; an addition of a new TS 3.6.2.6, ``Drywell Spray,'' to reflect 
the crediting of drywell spray for fission product removal; and a 
revision to TS 3.6.4.1, ``Secondary Containment,'' SR 3.6.4.1.1, to 
address short-duration conditions during which the secondary 
containment pressure may not meet the SR pressure requirement at DNPS. 
The license amendment requests are addressed separately.
    Under Part 50 of 10 CFR, paragraph 50.54(o), primary reactor 
containments for water-cooled power reactors are subject to the 
requirements of Appendix J to 10 CFR part 50. Appendix J specifies the 
leakage rate test requirements, schedules, and acceptance criteria for 
tests of the leak-tight integrity of the reactor containment and 
systems and components that penetrate the containment. Option B of 10 
CFR 50, Appendix J, ``Performance-Based Requirements,'' paragraph 
III.A, ``Type A Test,'' requires, among other things, that the overall 
integrated leakage rate must not exceed the allowable leakage rate 
(La) with margin, as specified in the TSs. The overall 
integrated leakage rate is defined in 10 CFR part 50, Appendix J, as 
``the total leakage rate through all tested leakage paths, including 
containment welds, valves, fittings, and components that penetrate the 
containment system.'' This includes the

[[Page 64176]]

contribution through the four main steam lines where each line contains 
two MSIVs in series. Paragraph III.B, ``Type B and C Tests,'' requires, 
among other things, that the sum of the leakage rates of Type B and 
Type C local leakage rate tests be less than the performance criterion 
(La) with margin as specified in the TSs. The allowable 
leakage rates set in the TSs ensure that the required dose limits, such 
as in 10 CFR 50.67, ``Accident source term,'' will not be exceeded.
    This requested exemption concerns the main steam system, which 
penetrates containment. The radiological consequences of MSIV leakage 
are modeled as a separate primary containment release path to the 
environment that bypasses secondary containment because MSIV leakage is 
not filtered through the standby gas treatment system like other 
containment leakage. The design-basis LOCA dose calculation assumes all 
MSIV leakage migrates to the turbine building and then to the 
environment. By currently including the main steam pathway leakage with 
the rest of the primary containment leakage test results, it is being 
accounted for twice: once as part of the actual containment leakage and 
again as part of the MSIV leakage used in the LOCA dose calculations.

III. 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 as described in 10 CFR 50.12(a)(2)(i)-
(vi) are present. The licensee asserted that special circumstances are 
present under 10 CFR 50.12(a)(2)(ii) because the 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 licensee submitted this exemption request as part of a license 
amendment request to increase the allowable MSIV leakage rate, which if 
approved, would permit an increase in allowable MSIV leakage rate that 
is excluded from the overall integrated leak rate Type A test 
measurement and excluded from the combined Type B and Type C test 
total. The licensee described its view on the special circumstances 
associated with the MSIV leakage path testing in its application dated 
October 21, 2019.

A. The Exemption Is Authorized by Law

    This exemption permits exclusion of the MSIV pathway leakage 
contribution from the overall integrated leakage rate Type A test 
measurement and from the combined leakage rate of all penetrations and 
valves subject to Type B and Type C tests. As stated above, 10 CFR 
50.12 allows the NRC to grant exemptions from the requirements of 10 
CFR part 50. The NRC staff has determined that granting the licensee's 
proposed exemption will not result in a violation of the Atomic Energy 
Act of 1954, as amended, or the Commission's regulations. Therefore, 
the exemption is authorized by law.

B. The Exemption Presents No Undue Risk to Public Health and Safety

    Type A tests to measure the containment system overall integrated 
leakage rate must be conducted under conditions representing design-
basis LOCA containment peak pressure. Type B pneumatic tests to detect 
and measure local leakage rates across pressure retaining, leakage-
limiting boundaries, and Type C pneumatic tests to measure containment 
isolation valve leakage rates, must be conducted to ensure the 
integrity of the overall containment system as a barrier to fission 
product release to reduce the risk from reactor accidents.
    In license Amendment Nos. 221 and Amendment 212 dated September 11, 
2006 (ADAMS Accession No. ML062070290), the NRC approved the use of the 
alternative source term (as prescribed in 10 CFR 50.67) in the 
calculations of the radiological dose consequences of design-basis 
accidents, including the design-basis LOCA, for DNPS. The NRC staff's 
safety evaluation accompanying these amendments acknowledged that once 
fission products are dispersed in the primary containment, their 
release to the environment is assumed to occur through three pathways: 
(1) The leakage of primary containment atmosphere; (2) the leakage of 
primary containment atmosphere through MSIVs; and (3) the leakage from 
emergency core cooling systems that recirculate suppression pool water 
outside of the primary containment. As noted above, however, leakage 
through the MSIVs is considered a separate pathway and is calculated as 
a separate contributor to the dose consequence analysis. As such, the 
inclusion of MSIV leakage as part of Type A and as part of Type B and C 
test results is not necessary to ensure the actual radiological 
consequences of design-basis accidents remain below the regulatory 
limit.
    The proposed exemption does not create any new accident precursors. 
Therefore, the probability of postulated accidents is not increased. 
Also, the consequences of postulated accidents are not significantly 
changed from the previously evaluated consequences associated with the 
design-basis LOCA as described in the alternative source term 
amendments. Therefore, there is no undue risk to public health and 
safety.

C. The Exemption is Consistent With the Common Defense and Security

    The proposed exemption excludes the MSIV pathway leakage 
contribution from the overall integrated leakage rate Type A test 
measurement and from the combined leakage rate of all penetrations and 
valves subject to Type B and Type C tests. This change to accounting 
for leakage rate measurement has no relation to security issues. 
Therefore, the exemption is consistent with the common defense and 
security.

D. Special Circumstances

    Under 10 CFR 50.12(a)(2)(ii) special circumstances include when, 
``[a]pplication 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 test requirements in Appendix J to 10 CFR part 50 ensure that 
leakage through containments or systems and components penetrating 
containments does not exceed allowable leakage rates specified in the 
technical specifications, and integrity of the containment structure is 
maintained during its service life. Option B of Appendix J identifies 
the performance-based requirements and criteria for preoperational and 
subsequent periodic leakage-rate testing.
    The licensee has analyzed the main steam pathway leakage separately 
from the overall containment integrated leakage; the local leakage 
across pressure-containing or leakage-limiting boundaries; and the 
containment isolation valve leakage in its dose consequence analyses. 
The dose consequences were found to be within the applicable acceptance 
criteria in 10 CFR 50.67, ``Accident source term,'' and the guidance of 
NRC Regulatory Guide 1.183, Revision 0, ``Alternative Radiological 
Source Terms for Evaluating Design Basis Accidents at Nuclear Power 
Reactors,'' dated July 2000 (ADAMS Accession No. ML003716792). The 
staff has reviewed the licensee's analysis and determined that the dose 
consequences of implementing the proposed change are

[[Page 64177]]

below the applicable acceptance criteria and the containment leaks will 
continue to be limited by the DNPS TSs.
    Therefore, because the underlying purposes of 10 CFR part 50, 
Appendix J, are still achieved, the special circumstances required by 
10 CFR 50.12(a)(2)(ii) for the granting of an exemption from 10 CFR 
part 50, Appendix J, Option B, Sections lII.A and III.B, exist.

E. Environmental Considerations

    The NRC staff determined that the issuance of the requested 
exemption meets the provisions of categorical exclusion 10 CFR 
51.22(c)(25) because there is: (i) No significant hazards 
consideration; (ii) no significant change in the types or significant 
increase in the amounts of any effluents that may be released offsite; 
(iii) no significant increase in individual or cumulative public or 
occupational radiation exposure; (iv) no significant construction 
impact; (v) no significant increase in the potential for or 
consequences from radiological accidents; and (vi) the requirements 
from which an exemption is sought involve inspection or surveillance 
requirements. Therefore, in accordance with 10 CFR 51.22(b), no 
environmental impact statement or environmental assessment need be 
prepared in connection with the NRC's issuance of this exemption. The 
basis for the NRC staff's determination is provided in the following 
evaluation of the requirements in 10 CFR 51.22(c)(25)(i)-(vi).
Requirements in 10 CFR 51.22(c)(25)(i)
    To qualify for a categorical exclusion under 10 CFR 
51.22(c)(25)(i), the exemption must involve ``no significant hazards 
consideration.'' The NRC staff evaluated whether the exemption involves 
no significant hazards consideration by using the standards in 10 CFR 
50.92(c), as presented below:
    1. Does the requested exemption involve a significant increase in 
the probability or consequences of an accident previously evaluated?
    Response: No.
    The proposed exemption would permit exclusion of the MSIV pathway 
leakage contribution from the overall integrated leakage rate Type A 
test measurement and from the sum of the leakage rates from Type B and 
Type C tests. The leakage of primary containment atmosphere through 
MSIVs is accounted for as a separate contributor to the design-basis 
LOCA dose consequence analysis. This exemption will allow the leakage 
testing to be performed in a manner consistent with the way MSIV 
leakage is modeled in the revised radiological consequence analysis 
submitted as part of the related license amendment request submitted in 
the letter dated October 21, 2019, as supplemented by letter dated May 
6, 2020. This change to the leakage rate measurement does not increase 
the probability or consequences of an accident previously evaluated.
    Therefore, the exemption does not involve a significant increase in 
the probability or consequences of an accident previously evaluated.
    2. Does the requested exemption create the possibility of a new or 
different kind of accident from any accident previously evaluated?
    Response: No.
    The proposed exemption does not involve a physical modification to 
the plant (i.e., no new or different type of equipment will be 
installed and there are no physical modifications to existing equipment 
associated with the proposed change). Similarly, it does not physically 
change any structures, systems, or components involved in the 
mitigation of any accidents.
    Therefore, the exemption does not create the possibility of a new 
or different kind of accident from any accident previously evaluated.
    3. Does the requested exemption involve a significant reduction in 
a margin of safety?
    Response: No.
    The proposed exemption does not alter a design basis or safety 
limit nor cause a limit to be exceeded. The proposed exemption allows 
the results of the TS required MSIV leakage pathway tests to no longer 
be accounted for as part of the overall integrated leakage rate Type A 
test measurement and as part of the sum of the local leakage rates from 
Type B and Type C tests. This change only affects which leakage rates 
are included in the Types A, B, and C results. This exemption will 
allow the leakage testing to be performed in a manner consistent with 
the way MSIV leakage is modeled in the revised radiological consequence 
analysis submitted as part of the related license amendment request.
    Therefore, the exemption does not involve a significant reduction 
in a margin of safety.
    Based on the evaluation above, the NRC staff has determined that 
the proposed exemption involves no significant hazards consideration. 
Therefore, the requirements of 10 CFR 51.22(c)(25)(i) are met.
Requirements in 10 CFR 51.22(c)(25)(ii)
    To qualify for a categorical exclusion under 10 CFR 
51.22(c)(25)(ii), the exemption must result in ``no significant change 
in the types or significant increase in the amounts of any effluents 
that may be released offsite.'' The proposed exemption allows the 
results of the TS-required MSIV leakage pathway tests to be accounted 
for only as part of the design-basis LOCA consequence analysis. This 
change only affects the total in which the leakage rates are included 
and does not change the frequency or pressure at which the testing must 
be performed. The underlying purpose of 10 CFR part 50, Appendix J, is 
to demonstrate by periodic testing and visual inspection that the 
primary reactor containment will be able to perform its function of 
providing an essentially leak-tight barrier against uncontrolled 
release of radioactivity to the environment. The inclusion of the MSIV 
leakage testing results in the design-basis LOCA serves the same 
purpose as the inclusion in the rate Type A test measurement and the 
sum of the leakage rates from Type B and Type C tests required by 
Appendix J, Option B, paragraphs III.A and III.B. Therefore, the 
proposed exemption will not significantly change the types of effluents 
that may be released offsite, or significantly increase the amount of 
effluents that may be released offsite. Therefore, the requirements of 
10 CFR 51.22(c)(25)(ii) are met.
Requirements in 10 CFR 51.22(c)(25)(iii)
    To qualify for a categorical exclusion under 10 CFR 
51.22(c)(25)(iii), the exemption must result in ``no significant 
increase in individual or cumulative public or occupational radiation 
exposure.'' The proposed exemption permits the exclusion of the MSIV 
leakage pathway results from the Type A test measurement and the sum of 
the leakage rates from Type B and Type C tests required by Appendix J, 
Option B, paragraphs III.A and III.B, and has no impact on, or change 
to, fuel or core design. Additionally, the TSs still require that the 
MSIV leakage rates be tested and maintained below set limits. As such, 
the calculated public and occupational doses will remain essentially 
the same. Therefore, the proposed exemption will not significantly 
increase individual or cumulative public or occupational radiation 
exposure. Therefore, the requirements of 10 CFR 51.22(c)(25)(iii) are 
met.
Requirement in 10 CFR 51.22(c)(25)(iv)
    To qualify for a categorical exclusion under 10 CFR 
51.22(c)(25)(iv), the exemption must result in ``no significant 
construction impact.'' The exemption does propose any changes to the 
site,

[[Page 64178]]

alter the site, or change the operation of the site. Therefore, there 
is no significant construction impact. Therefore, the requirements of 
10 CFR 51.22(c)(25)(iv) are met.
Requirement in 10 CFR 51.22(c)(25)(v)
    To qualify for a categorical exclusion under 10 CFR 
51.22(c)(25)(v), the exemption must involve ``no significant increase 
in the potential for or consequences from radiological accidents.'' The 
proposed exemption does not remove the requirement to perform leakage 
rate testing of the MSIVs. This exemption will allow the leakage 
testing to be performed in a manner consistent with the way MSIV 
leakage is modeled in the revised radiological consequence analysis 
submitted as part of the related license amendment request. Therefore, 
this change to the leakage rate measurement does not result in a 
significant increase in the potential for or consequences from 
radiological accidents. Therefore, the requirements of 10 CFR 
51.22(c)(25)(v) are met.
Requirement in 10 CFR 51.22(c)(25)(vi)
    To qualify for a categorical exclusion under 10 CFR 
51.22(c)(25)(vi)(C), the exemption must involve inspection or 
surveillance requirements. The exemption seeks to permit exclusion of 
the MSIV leakage from the overall integrated leak rate Type A test 
measurement and the combined leakage rate of all penetrations and 
valves subject to Type B and Type C tests required by Appendix J to 10 
CFR part 50. Appendix J specifies the leakage rate test requirements, 
schedules, and acceptance criteria for tests of the leak-tight 
integrity of the reactor containment, and systems and components that 
penetrate the containment. Therefore, the exemption involves a 
surveillance requirement. Therefore, the requirements of 10 CFR 
51.22(c)(25)(vi) are met.
Conclusion
    Based on the above, the NRC staff concludes that the proposed 
exemption meets the eligibility criteria for the categorical exclusion 
set forth in 10 CFR 51.22(c)(25). Therefore, in accordance with 10 CFR 
51.22(b), no environmental impact statement or environmental assessment 
need be prepared in connection with the NRC's issuance of this 
exemption.

IV. Conclusions

    Accordingly, the Commission has determined that, pursuant to 10 CFR 
50.12, the exemption 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, special circumstances are present. 
Therefore, the Commission hereby grants EGC a permanent exemption (1) 
from the requirements of 10 CFR part 50, Appendix J, Option B, Section 
III.A, to allow exclusion of the MSIV pathway leakage from the overall 
integrated leakage rate measured when performing a Type A test; and (2) 
from the requirements of 10 CFR part 50, Appendix J, Option B, Section 
III.B, to allow exclusion of the MSIV pathway leakage from the combined 
leakage rate of all penetrations and valves subject to Types B and C 
tests for DNPS.
    This exemption is effective upon issuance.

    Dated: 5th day of October 2020.

    For the Nuclear Regulatory Commission.

David J. Wrona,
Acting Deputy Director, Division of Operating Reactor Licensing 
Office of Nuclear Reactor Regulation.
[FR Doc. 2020-22371 Filed 10-8-20; 8:45 am]
BILLING CODE 7590-01-P