ML20195K027
| ML20195K027 | |
| Person / Time | |
|---|---|
| Issue date: | 06/03/1999 |
| From: | Dicus G NRC COMMISSION (OCM) |
| To: | Vietticook A NRC OFFICE OF THE SECRETARY (SECY) |
| Shared Package | |
| ML20195J986 | List: |
| References | |
| REF-10CFR9.7 SECY-99-133-C, NUDOCS 9906210190 | |
| Download: ML20195K027 (3) | |
Text
FI NOTATION VOTE RESPONSE SHEET TO:
Annette Vietti-Cook, Secretary FROM:
COMMISSIONER DICUS
SUBJECT:
SECY-99-133 - FINAL REVISION TO 10 CFR 50.65 TO REQUIRE LICENSEES TO PERFORM ASSESSMENTS BEFORE PERFORMING MAINTENANCE Approved x
Disapproved Abstain Not Participating COMMENTS:
I approve the final rulemaking for 10 CFR 50.65 and support including at the end of paragraph (a)(4)theACRSlanguage"fortheproposedconfiguration." Staff should correct the attached editorial changes to the FRN.
ddh. A Scu; QATUl%E/C
[w 3 /9ff DATQ Entered on "AS" Yes x No 9906210190 990618 RES DE E PDR
f' 3
/
11 the total time that the function may be demanded." Also according to that document, under the definition of " unavailability," is the following statement: "An SSC that is required to be available for automatic operation must be available and respond without human action." Additionally, in the instance where an SSC is taken old of service for testing but could be manually activated,
- the NRC has accepted that, as long as the dedicated operator's written procedure specifies a single action that would permit an automatic initiation of the out-of-service SSC in the event of an accident or transient during the test, the SSC could be considered available. (Meeting Summary - November 19,1991 NRC/NUMARC Public Meeting on the Development of Guidance Documents for the implementation of the Maintenance Rule (10 CFR 50.65), R.P.
Correia, Office of Nuclear Reactor Regulation, memorandum to E.W. Brach, Office of Nuclear _
Reactor ulation, dated November 23,1991.) The NRC's expectation is that, by procedu the dedicated operator is stationed at the equipment and is ready and qualified to perform that singh action in a moment. - An acceptable single action could be the rapid repositioning of a switch or a lever; an unacceptable action would be racking in a breaker or, in some instances, opening a manual gate valve.
With respect to risk-informing the maintenance rule definition of availability, the reliance of initial availability performance measures on probabilistic risk assessment (PRA) data provided such a basis. However, in quality maintenance programs, availability is monitored to identify and trend the performance of equipment, thereby permitting certain conclusions to be drawn about the effectiveness of the equipment's maintenance program. Paragraph (a)(3) of the rule seguires that the prevention of SSC failures (reliability) through maintenance is appropriately balanced against the objective of minimizing unavailability. Omitting unavailability time from the maintenance effectiveness determination analysis is flawed logic. Omitting unavailability time because, in an accident scenario, the equipment may not be needed for the time it may take to
i 13 Resoonse. The NRC does not expect licensees to develop numerical models for assessing all possible combinations of low-risk-significant SSCs. The regulatory analysis states i
\\
/
that the complexity of assessments to be performed can vary, depending upon the configuration of SSCs to be maintained on line or out of service. It was presumed that assessments involving SSCs having little bearing on safety could be performed in an uncomplicated, deterministic manner and that the cost of the overall program would be dominated by the need for assessment of combinations of SSCs, which, when taken out of service simultaneously, could have an adverse effect on the safe operation of the facility. Additionally, the licensee controls the degree of complexity of the proposed configuration and thereby controls the level of sophistication required for the assessment. Consequently, the licensee should not propose to 1
enter a plant configuration the complexity of which exceeds the licensee's ability to assess.
- 13. Acolication to decommissionino olants.
Comment. One commentor presented concems regarding the application of the rule j plants in a decommissioning status. The commentor requested that, as part of this rulemaking, the NRC remove the applicability of the rule to decommissioning status plants following some modest level of fission product decay.
Resoonse. This rulemaking is focused on requiring pre-maintenance assessments of plant risk. However, the NRC is considering the issue in a separate rulemaking activity.
l
\\
111.
The Final Rule The final rule amends 10 CFR 50.65 as follows:
- 1. An introductory paragraph has been added to 10 CFR 50.65 clarifying that the rule gm applies under all conditions of operation, including hdown. This introductory language 3
x, reads as follows:"The requirements of this section are applicable during all conditions of plan g
c e
- - - - -.