ML20035D786
| ML20035D786 | |
| Person / Time | |
|---|---|
| Issue date: | 12/23/1991 |
| From: | Fraley R Advisory Committee on Reactor Safeguards |
| To: | Advisory Committee on Reactor Safeguards |
| Shared Package | |
| ML20035D698 | List: |
| References | |
| ACRS-2791, NUDOCS 9304140044 | |
| Download: ML20035D786 (9) | |
Text
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UNITED STATES 8
j NUCLEAR REGULATORY COMMISSION c
E r
ADVISORY COMMITTEE ON REACTOR SAFEGUARDS c
o, WASHINGTON, D. C. 20555 s...../
December 23, 1991 MEMORANDUM FOR:
ACRS Members FROM:
Raymon
'. Fraley
SUBJECT:
Appointment of New Members During the December Committee meeting you discussed a proposed version (Draf t #5) of a press release calling for the nomination of candidates to be considered for membership.
Attached is the final draft as best as I could reconstitute it from my notes.
I am providing it to you for further consideration as appropriate.
I expect a short session will be scheduled for discussion during the January meeting and final Committee approval.
If you have any comments or suggested changes that need resolution, please let me know as soon as possible.
Attachment:
press Release
- NRC Invites Public to Submit Nominations for ACRS, Final Draft dtd. 12/14/91.
cc:
M.
F. Lee w/ attachment 9304140044 920312 ATTACHMENT E gj PDR ACRS 2791 PDR 7/
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DRAFT #1/12/14/91 WARD /El-Zeftawy/ ruby Ruby Mtg. Disk /KEYTECH.MME MEMORANDUM TO FILE FROM:
David A. Ward, Chairman
SUBJECT:
KEY TECHNICAL ISSUES RECOMMENDED BY ACRS IN COMING MONTHS I
1 This memorandum documents plans for ACRS study of certain key 2
technical issues as discussed at the 380th meeting, December 12-14, 3
1991.
Preliminary discussion of these issues had been carried out 4
in an ad hoc subcommittee meeting in Baltimore on November 22-24, 5
1991.
Two groups of issues are described below.
The first six are 1
6 related to ALWR design certification and ACRS programs need to be l
carried out on a schedule compatible with the overall NRC certifi-8 cation program.
Issues 7 through 12 have more general application 9
to future NRC programs.
In each case the issue is described by a i
10 series of questions and the ACRS plan for its action is briefly 11 summarized.
j 12 ISSUES RELATED TO ALWR DESIGN CERTIFICATION 13 1.
What are the safety and regulatory implications of integrated' 14 computer-based control and protection systems?
15 Can these systems introduce unique kinds of plant failures, especially common-mode
- failures, which are outside the ATTACHMENT B
s MEMORANDUM TO FILE 2
17 existing experience base for NPPs, but which might become
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18 important given wide use of computer-based systems?
19 How can NRC regulate the design and operation of such systems 20 without unnecessarily limiting innovation?
21 Is there professional staff within the NRC adequate for 5
22 dealing with these issues?
23 What are the man-machine implications of these sys.tems?
h 24 A somewhat broader question -- is there a need for " General Human Factors Criteria,"
paralleling the General Design 26 Criteria of 10 CFR 50, Appendix A?
27 ACRS action:
Already underway is a planned series of subcom-28 mittee meetings extending through 1992 involving NRC staff, 29 industry, and subject matter experts.
Consideration will be 30 given to co-sponsoring an international conference on the 31 subject somewhere along the way. Af ter necessary assimilation 32 of information, ACRS will synthesize important lessons and 33 make recommendations to the Commission.
These should be 34 provided in late 1992.
2.
Should new means for specifying system and component reliabil-61 36 ity be established.
If deterministic criteria are to be used, I
s MEMORANDUM TO FILE 3
37 should NRC move beyond the " single failure criterion" as the 38 keystone of safety design?
39 Should "N+2" be required for certain systems?
40 Should regulations provide reliability requirements, rather 41 than deterministic ones?
42 Should there be a limit on the reliability level that can be 43 credited to and expected from any given system, perhaps no g 7_
44 greater than a value that can be demonstrated by ordinary, 45 transparent means, e.g.,
99 percent?
I 46 Should reliability requirements be systematically allocated 47 among systems and components, derived from a top level overall 48 goal -- related to the Safety Goal?
49 Should the distinction between safety and nonsafety systems be fq 50 maintained?
i 51 ACRS action:
The Committee agreed to actively pursue these 52 questions; a specific plan of action remains to be developed.
53 The goal would be to make recommendations to the Commission in 4
54 time to. influence the design and review of the " passive" LWR and later designs, i.e.,
by mid to late 1992.
l MEMORANDUM TO FILE 4
26 3.
Should separation requirements for redundant safety trains be 57 upgraded to include explicit criteria to account for more 58 subtle environmental threats than are considered in existing 59 regulatory practice?
Examples are adverse effects of the 60 spread of smoke, heat (as though HVAC systems), steam, hot l
61 gases, water, and spurious or real fire extinguishing efforts.
I i
i 62 Are existing standards and requirements adequate to ensure i
63 that there can be no undesirable interdependence among i
64 supposedly separate systems or trains because of common (or l
65 inadequately separated) service and support systems especially 66 in the case of non-safety systems?
i 67 Should unwanted actions by affected components, as well as (p
68 failures to act, be considered?
i 69 ACRS action:
ACRS will, over the next several months, hold 70 subcommittee meetings with
- staff, vendors, and EPRI to l
71 determine present requirements and practices relative to these I C]
i 73 issues, using the ABWR and APWR work as examples. Recommenda-i 73 tions for bolstering regulations or regulatory practices will 74 be made to the Commission following a period of discussion and i
75 debate, in mid 1992.
I i
4.
Should NRC require certain design features to deal explicitly Zo i
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with control of risk during shutdown and low power operations?
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t MEMORANDUM TO FILE 5
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.4 ACRS action:
The Committee agreed to follow the NRC program I
79 closely.
We will look to see if consideration is being given 80 to expanding the program to address the need for possible
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r 81 fundamental redesign of certain plant systems (e.g., handling
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83 heavy loads over an open reactor core) to reduce the opportu-t 83 nities for events that lead to shutdown risks.
84 5.
Should the motivation for improving ALWR plants be to -
85 a.
make them safer (i.e., reduce the "mean" risk values)?
1 i
86 b.
increase " robustness" (i.e., reduce uncertainty)?
i 87 c.
keep them safe, but permit cheaper construction and 88 operation?
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89 Is the Safety Goal a good enough definition of how safe future 90 plants should be?
If the answer is yes, why are we trying to 23 91 improve them?
If the answer is no, what is an appropriate 92 goal?
l 93 ACRS action:
After discussion the Committee reached no kN 94 conclusions, nor did it develop plans for further review.
6.
Should a revised set of DBAs or criteria be required of new p
plant designs, e.g., taking more explicit account of severe accidents?
25 we 1
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MEMORANDUM TO FILE 6
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97 ACRS action:
The ACRS letter of May 17, 1991 on containment l
98 criteria proposed that containment designs for the passive LWR f
I 99 generation of plants should be based on severe accident 100 criteria.
The Committee agreed that this general approach
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101 would be useful for other systems and more advanced designs, i
102 but no specific plan of action was developed.
103 MORE GENERAL ISSUES i
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104 7.
Important new safety issues might arise in the future, in new 105 or old plants.
What might they be?
I I
ACRS action:
After discussion the Committee reached no 107 conclusions nor planned any action beyond arranging for a 17 108 briefing on the status of advanced reactor developments around 109 the world, and continue to be briefed on operating experience.
110 8.
What are the most important issues involving the safety in
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111 operating the current generation of plants?
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112 ACRS action: After discussion the Committee developed no new 30 113 agenda for focusing on or pursuing this issue, beyond continu-114 ing to follow on operating experience.
i 9.
Are there important issues with regard to license renewal that l
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116 have not been identified or are being neglected?
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i MEMORANDUM TO FILE 7
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ACRS action:
The Committee concluded that the NRC program is 118 proceeding well and that beyond following this, no particular l
3,2 i 119 ACRS action beyond our normal activities is warranted.
The 130 Plant License Renewal Subcommittee will take the lead on this 121 action.
l 122 10.
Should the Safety Goal Policy be broadened to incorporate an
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133 explicit guideline or goal related to land or resource i
124 contamination, separate from the health effects goals?
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135 ACRS action:
The Committee will discuss this at a meeting in 3g 126 early 1992.
127 11.
Can and should semi-arbitrary containment challenges be l
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I 128 specified for PIUS, CANDU, PRISM, and MHTGR to serve as a D
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129 basis for containment designs? Should ACRS develop proposals?
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130 ACRS action: The Committee agreed to consider a program along i
131 the lines of that it. carried out for the LWR containment i
132 criteria effort -- designate lead Member to develop strawman %
l 133 position, solicit input from experts, debate and develop j
134 consensus, develop recommendations for Commission. A schedule i
i 135 remains to be developed.
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12.
Does commitment to the concept of physical defense-in-depth 131 mean that MHTGR and PRISM must have traditional containments?
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l MEMORANDUM TO FILE 8
lad ACRS action:
The Committee will discuss this at a future 33 139 neeting.
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