ML111230453
| ML111230453 | |
| Person / Time | |
|---|---|
| Site: | Shoreham File:Long Island Lighting Company icon.png |
| Issue date: | 11/20/1981 |
| From: | Harold Denton Office of Nuclear Reactor Regulation |
| To: | Office of Nuclear Reactor Regulation |
| Shared Package | |
| ML111230451 | List: |
| References | |
| FOIA-82-176 NUDOCS 8201200448 | |
| Download: ML111230453 (5) | |
Text
o UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, 0. C. 20555
',o NOV 2 0 1981 MEMORANDUM FOR:
All NRR Personnel FROM:
Harold R. Denton, Director Office of Nuclear Reactor Regulation
SUBJECT:
STANDARD DEFINITIONS FOR COMMONLY-USED SAFETY CLASSIFICATION TERMS Litigation of one of the principal issues in the TMI-I Restart Hearing brought to light the fact that there is not complete consistency among all elements of the NRR staff in the application of safety classification terms used frequently in the conduct of NRR's safety review and licensing activities. More specifi cally, it appears that terms "important to safety," "safety grade," and "safety related" have been used at times interchangeably, or in.
ways not completely consistent with the definitions -and usage of such terms in the regulations, and which do not fully reflect the intent of the regulations or current licensing practice.
Efforts have been underway for some months now to develop guidance for the consistent usage of these terms. These efforts have included: (a) review of a large number of Reg Guides and SRP's, in conjunction with parts of the regula tions upon which they are based, for consistency in the application of safety classification terminology, (2) extensive discussions among cognizant NRR, RES (Stds. Devel.) and ELD representatives regarding proper interpretation and application of such terms, including consideration of alternative "standard" definitions and (3) consultation with the cognizant ACRS Subcommittee regarding these matters, and consideration by the full ACRS as well.
As a result of these efforts, I am endorsing and prescribing for use-by all NRR personnel the standard definitions set forth in the enclosure to this letter.
It should be noted that in connection With long-term efforts to develop means for ranking reactor plant systems with respect to degree of importance to safety, and in connection with related efforts to develop a graded Q.A. approach in reactor licensing, the general question of safety classifications and safety classification terminologies will be reexamined; and this could result in changes to the defini tions set forth in the enclosure or perhaps in development of a completely new scheme in this regard.
For the time being, however, the definitions in the en closure should be considered "standard" and should be applied consistently by all NRR personnel in all aspects of our safety review and licensing activities and should be appropriately reflected in our regulatory guidance documents.
S T DeoQ -:rA(-
CF I&S "J
'All NRR Personnel
-2 It -i-s expected :thatminor editorial -revisions will have -to be made to some existing Reg Guides and SRP's in order to-make :their wording consistent with these definitions. iYou should review the regulatory 'guidance documents within your:purview in this regard and recommend the necessary changes; it is not
- expected.that.this will involve :.extensive revision efforts. I want to make clear that my interest here is.only in.establishing consistency in the language used by.all cognizant groups within NRR in expressing our technical requirements.
It is :not my Intention. by this-ac.tion,to dictate.new technical requirements, to Smodify existing technical requirements, or to broaden the existing scope of NRR licensing review.
- Harold R. Denton,- Director Office of Nuclear Reactor Regulation
Enclosure:
Definition,of Terms
Q 0
DEFINITION OF TERMS Important to Safety 0
Definition -
From 10 CFR 50, Appendix A (General Design Criteria) -
see first paragraph of "Introduction."
"Those structures, systems, and components that provide reasonable assurance that the facility can be operated without undue risk to the health and safety of the public:"
e Encompasses the broad class of plant features, covered (not necessarily explicitly) in the General Design Criteria, that contribute in important way
'to safe operation and protection of the pLblic in all phases and aspects of facility operation- (i.e., normal pperation and transient control as well as accident mitigation).
a Includes Safety-Grade (or Safety-Related) as a subset.
Safety-Related e
Definition -
From 10 CFR 100, Appendix A -
see sections III.(c), VI.a.(l), and VI.b.(3).
Those structure, systems, or components designed to remain functional for the SSE (also termed 'safety features') necessary to assure required safety functions, i.e.:
(1) the integrity of the reactor coolant pressure boundary; (2) the capability to shut down the reactor and maintain it in a safe shutdown condition; or (3) the capability to prevent or mitigate the consequences of accidents which could result in potential off-site exposures comparable to the guideline exposures of this part.
- Subset of "Important to Safety"
- Regulatory Guide 1.29 providesan LWR-generic, function-oriented listing of "safety-related" structures, systems; and components needed to-provide or perform'required safety functions. Additional information (e.g., NSSS type, BOP design A-E, etc.) is needed to generate the complete listing of safety related SSC's for any specific facility.
Note:
The term "safety-related" also appears in 10 CFR 50, Appendix B (Q.A. Program Requirements); however, in that context it is framed in somewhat different language than its definition in 10 CFR 100, Appendix A. That difference in language between the two appendices has contributed to confusion and misunderstanding regarding the exact meaning of. "safety-related" and its relationship to "important to safety" and "safety-grade." A revision to the language of Appendix B has been proposed to clarify this situation and remove any ambiquity in the meaning of these terms.
Enclosure
Safety-Grade,
.Term not used explicitly in regulations-bu.t. widely used/applied by staff and industry in: safety review-process-.
9-: Equivalent to "Safety-Related,'" i.e.,. both terms apply., to the same subset of the broad-class. "Important. to. Safety."'-