[Federal Register Volume 59, Number 180 (Monday, September 19, 1994)]
[Unknown Section]
[Page 0]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 94-23136]
[[Page Unknown]]
[Federal Register: September 19, 1994]
VOL. 59, NO. 180
Monday, September 19, 1994
NUCLEAR REGULATORY COMMISSION
10 CFR Part 50
RIN 3150-AF04
Steam Generator Tube Integrity for Operating Nuclear Power Plants
AGENCY: Nuclear Regulatory Commission.
ACTION: Advance notice of proposed rulemaking.
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SUMMARY: The Nuclear Regulatory Commission is considering amending its
regulations regarding steam generator tube surveillance and maintenance
at operating nuclear power plants. The advanced notice of proposed
rulemaking (ANPRM) considers regulatory approaches that would maintain
adequate assurance of steam generator tube integrity while allowing a
more appropriate approach to steam generator surveillance and
maintenance activities at nuclear power plants. The NRC is issuing this
ANPRM to invite comments, advice, and recommendations from interested
parties on the proposed steam generator rule.
DATES: The comment period expires December 5, 1994. Comments received
after this date will be considered if it is practical to do so, but the
Commission is able to assure consideration only for comments received
on or before this date.
ADDRESSES: Mail comments to: The Secretary of the Commission, U.S.
Nuclear Regulatory Commission, Washington, DC 20555, Attention:
Docketing and Services Branch. Deliver comments to: 11555 Rockville
Pike, Rockville, Maryland, between 7:45 am and 4:15 pm on Federal
workdays. Examine copies of comments received at: The NRC Public
Document Room, 2120 L Street NW. (Lower Level), Washington, DC.
FOR FURTHER INFORMATION CONTACT: T.A. Reed, Office of Nuclear Reactor
Regulation, U.S. Nuclear Regulatory Commission, Washington, DC 20555,
telephone (301) 504-2795.
SUPPLEMENTARY INFORMATION:
Background
Steam generator tube degradation at nuclear power plants continues
to be a problem for the nuclear industry. Industry actions have been
effective in controlling many of the forms of degradation experienced
in late 1970s and early 1980s; however, new degradation mechanisms
continue to occur. State-of-the-art nondestructive inspection and tube
repair methods have improved significantly in recent years. Changes in
types of degradation being experienced and improvements in inspection
and tube repair technology have made the NRC's existing regulatory
requirements and guidance out-of-date and in some cases overly
conservative or impractical. In addition, the NRC staff has determined
that factors other than the material tube degradation should be
considered when assessing tube integrity.
The objective of the proposed rule would be to maintain steam
generator tube integrity such that there is an extremely low
probability of steam generator tube leakage that could result in core
damage or otherwise exceed allowable off-site doses while allowing a
reasonable approach to steam generator surveillance and maintenance
activities (i.e., degradation-specific management). A performance-based
rule with quantitative criteria would achieve the desired goals without
being prescriptive in nature. A flexible rule would accommodate changes
in operating experience and technology while giving incentives for the
industry to continue to improve the state-of-the art tube inspection
and repair methods. Incorporation of an integrated approach considers
the overall factors of safety and risk, including systems and
radiological assessments.
The NRC staff's rulemaking effort would establish a flexible
framework that allows steam generator tube integrity to be addressed
using a degradation-specific management approach. This approach
involves establishing and implementing preventive measures such as
inspection, evaluation, and repair criteria that are applicable to
distinct steam generator degradation mechanisms, and default criteria
for the remaining forms of steam generator tube degradation where
experience does not enable a degradation-specific approach. The NRC
staff's rulemaking effort would also address issues relevant to
containment bypass probability and severe accidents associated with
bypass of containment. The NRC staff would consider application of more
realistic analytical assumptions, as well as defense-in-depth measures
that could be implemented to further ensure safety. The proposed rule
would acknowledge new degradation mechanisms and technological advances
in inspection techniques to improve characterization of these
mechanisms.
Recognizing that the steam generator rule would contain broad
criteria while an associated regulatory guide would contain more
detailed guidance, a proposed outline of the NRC staff's perception of
the necessary elements of a steam generator rule follows:
(a) Applicability
(b) Definitions
(c) Requirements
(1) Licensee Surveillance and Maintenance Program
(i) Preservice and Inservice Inspection Program
(ii) Water Chemistry Program
(iii) Tube Integrity
(iv) Repair Criteria
(v) Repair Methods
(vi) Nondestructive Examination Considerations
(vii) Normal Operating Primary-to-Secondary Leakage Monitoring/
Limits
(2) Accident Mitigation
(i) Accident Condition Primary-to-Secondary Leakage Monitoring
(ii) Procedures
(iii) Operator Training
(3) Radiological Consequences
(d) Severe Accident Considerations
(e) Implementation
Specific Considerations
Comments, advice and recommendations on a proposed rule reflecting
the aforementioned features and any other pertinent points are invited
from all interested persons. Particularly, comments and supporting
reasons are requested on the following questions:
1. What are appropriate performance based criteria that should be
included in the steam generator proposed rule to address steam
generator inspection scope and frequency, nondestructive examination
(NDE) equipment capabilities, NDE data analyst capabilities,
performance demonstration and qualification of NDE systems, steam
generator water chemistry requirements, flaw acceptance criteria, and
steam generator tube repair methods?
2. What are the appropriate performance based criteria that should
be incorporated into the proposed rule to define adequate tube
integrity (vis-a-vis 10 CFR 50 Appendix A GDC 14)?
3. What information should be part of the steam generator proposed
rule, and what information should be addressed in a Regulatory Guide?
4. How should the proposed rule be structured to assure that
licensees make use of available operational experience and data
applicable to steam generator integrity, and that licensees can
establish and readily update steam generator programs?
5. How should the proposed rule address new or replacement steam
generators versus degraded steam generators?
6. Should the Regulatory Guide be prescriptive in terms of the
methods to be used to ensure that the proposed rule's performance
criteria are achieved?
7. Should the proposed rule require licensees to submit their
programs to NRC for review and approval before implementation?
8. What requirements should be instituted to provide improved or
additional monitoring of primary-to-secondary leakage as a means to
enhance defense-in-depth relative to steam generator tube degradation?
9. What changes should be made in the NUREG-0800 radiological
calculation guidance used to address the safety significance of steam
generator tube leakage and rupture?
10. What beyond design basis considerations related to steam
generator tube integrity should be addressed during the rulemaking
process (e.g., the potential for containment bypass)?
11. How should tube failure prevention and mitigation measures be
balanced in the proposed rule?
12. What interim measures are appropriate to allow continued
operation of a unit in which new degradation modes are discovered?
13. Is the proposed rulemaking action considered a necessary or
preferred course of action for addressing steam generator maintenance
and surveillance issues, or are there other alternative regulatory
mechanisms that are equally effective for addressing these issues? If
alternatives to rulemaking are preferred, describe the preferred
alternatives, including the pros and cons of pursuing the alternative
course of action.
14. How should the steam generator rule or associated Regulatory
Guide address the following technical issues: (1) Calculation of tube
leakage following postulated events such as the main steam line break
and the potential for this leakage to exceed the make-up capacity of
the refueling water storage tank (supply source for the emergency core
cooling system), (2) application of eddy current parameters such as
voltage that are indirect measures of tube structural or leakage
integrity (as compared to more direct measures such as crack depth or
crack length), and (3) calculation of radiologically significant
isotope concentrations in released materials (I-131 equivalent)
following postulated events such as the main steam line break with
steam generator tube leakage where there is a paucity of data on
fission product iodine release rates.
The preliminary views expressed in this notice may change in light
of comments received. In any case, there will be an opportunity later
for additional public comment in connection with any proposed rule that
may be developed by the NRC.
List of Subjects in 10 CFR Part 50
Antitrust, Classified information, Criminal penalties, Fire
protection, Intergovernmental relations, Nuclear power plants and
reactors, Radiation protection, Reactor siting criteria, Reporting and
record keeping requirements.
Authority: Secs. 102, 103, 104, 105, 161, 182, 183, 186, 189, 68
Stat. 936, 937, 938, 948, 953, 954, 955, 956, as amended, sec. 234,
83 Stat. 1244, as amended (42 U.S.C. 2132, 2133, 2134, 2135, 2201,
2232, 2233, 2236, 2239, 2282); secs. 201, as amended, 202, 206, 88
Stat. 1242, as amended 1244, 1246 (42 U.S.C. 5841, 5842, 5846).
Section 50.7 also issued under Public Law 95-601, sec. 10, 92
Stat. 2951 (42 U.S.C. 5851). Section 50.10 also issued under secs.
101, 185, 68 Stat. 936, 955, as amended (42 U.S.C. 2131, 2235); sec.
102, Public Law 91-190, 83 Stat. 853 (42 U.S.C. 4332). Sections
50.13, 50.54(dd), and 50.103 also issued under sec. 108, 68 Stat.
939, as amended (42 U.S.C. 2138). Sections 50.23, 50.35, 50.55, and
50.56 also issued under sec. 185, 68 Stat. 955 (42 U.S.C. 2235).
Sections 50.33a, 50.55a and Appendix Q also issued under sec. 102,
Public Law 91-190, 83 Stat. 853 (42 U.S.C. 4332). Sections 50.34 and
50.54 also issued under sec. 204, 88 Stat. 1245 (42 U.S.C. 5844).
Sections 50.58, 50.91, and 50.92 also issued under Public Law 97-
415, 96 Stat. 2073 (42 U.S.C. 2239). Section 50.78 also issued under
sec. 122, 68 Stat. 939 (42 U.S.C. 2152). Sections 50.80-50.81 also
issued under sec. 184, 68 Stat. 954, as amended (42 U.S.C. 2234).
Appendix F also issued under sec. 187, 68 Stat. 955 (42 U.S.C.
2237).
Dated at Rockville, Maryland, this 8th day of September 1994.
For the Nuclear Regulatory Commission.
James M. Taylor,
Executive Director for Operations.
[FR Doc. 94-23136 Filed 9-16-94; 8:45 am]
BILLING CODE 7590-01-P
