ML20057E253
| ML20057E253 | |
| Person / Time | |
|---|---|
| Issue date: | 09/21/1993 |
| From: | Taylor J NRC OFFICE OF THE EXECUTIVE DIRECTOR FOR OPERATIONS (EDO) |
| To: | Rogers NRC COMMISSION (OCM) |
| Shared Package | |
| ML20057E254 | List: |
| References | |
| NUDOCS 9310080179 | |
| Download: ML20057E253 (5) | |
Text
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jg UNITED STATES NUCLEAR REGULATORY COMMISSION g
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September 21, 1993 MEMORANDUM f0R:
Commissioner Rogers FROM:
James M. Taylor Executive Director for Operations
SUBJECT:
SECY-93-190, REGULATORY APPROACH TO SHUTDOWN AND LOW-POWER OPERATIONS In your memorandum of August II,1993, you requested that the staff evaluate options to the rule it is developing to implement the safety enhancements that.
resulted from its evaluation of risks associated with low-power and shutdown operations. You asked that the staff consider a performance-based rule or a generic letter that would request voluntary adoption of proposed staff positions, in advance of the final policy paper.
The staff is developing a performance-based rule to address low-power and shutdown operations risks.
In recognition of the difficulties in implementing a numerical performance goal, the staff will develop a rule which focuses on the critical safety functions which must be satisfied during those shutdown conditions which present the highest risk. This a)proach avoids the complications of establishing numerical criteria tant appropriately treat the uncertainties in estimates of reliability, especially for humans who are essential in mitigating accidents during shutdown operations.
We anticipate that the rule will require an outage planning process similar to the high level goals outlined in NUMARC 91-06, " Guidelines for Industry Action to Assess Shutdown Management." We will establish broad requirements in this rule for redundancy of systems providing key safety functions (e.g., decay heat removal and inventory addition) when in shutdown operation. The specific equipment to be used to achieve this redundancy will not be specified in the rule. The staff will ensure that reliable systems are provided and will consider the use of non-safety as well as safety systems to meet the performance standards. The necessary equipment will be established on a plant-specific basis and will be incorporated in technical specifications.
The staff is developing model technical specifications that licensees will use to translate the performance based requirements of the rule to plant-specific requirements. The staff will issue a' generic letter which will provide the staff's proposed technical specifications. Use of a generic letter in this manner is consistent with past staff practice for promulgating new technical specifications. To ensure that these technical specifications will be 9310000179930$1 i
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Commissioner Rogers i readily accepted and adopted by licensees, we have developed model technical specifications as part of the Technical Specification Improvement Program. We will specifically encourage the owners groups to identify alternate' approaches to provide the required redundancy. We have corresponded with the owners groups and have initiated discussions with these groups to develop a mutually 1
acceptable set of technical specifications.
Originalsigned by James M. Taylor James M. Taylor Executive Director for Operations cc:
The Chairman Commissioner Remick Commissioner de Planque OGC SECY OCA OPA DISTRIBUTION Central Files SRXB r/f PDR JMTaylor JSniezek HThompson TEMurley/FMiraglia WTRussell JPartlow JBlaha EBeckjord I
TGody DCrutchfield ACThadani (GT0009230)
RJones MCaruso EDO (GT0009230)
NRR Mailroom (GT0009230)
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FINAL REPLY
- l Commissioner Rogers TO-James M. Taylor l
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Executive Director DESC:
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SECY-93-190, REGULATORY APPROACH TO SHUTDOWN AND Taylor LOW-POWER OPERATIONS - REQUEST POSSIBILITY OF ONE Sniezek j
OR MORE OPTIONS TO A PRESCRIPTIVE RULE, INCLUDING Thompson i
A PERFORMANCE-BASED RULE OR A GENERIC LETTER Blaha Beckjor.d, RES DATE: 08/12/93:
i ASSIGNED TO:
CONTACT.
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1 MEMORANDUM FOR:
Commissioner Rogers i
FROM:
James M. Taylor Executive Director for Operations i
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SUBJECT:
SECY-93-190, REGULATORY APPROACH TO SHUTDOWN AND LOW-POWER OPERATIONS j
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In your memorandum of August 11, 1993, you requested that the staff evaluate options to the-prescriptive-rule it is developing to implement the safety enhancements that resulted from its evaluation of risks associated with low-l power and shutdown operations. You asked that the staff consider a l
performance-based rule or a generic letter that would request voluntary j
l adoption of proposed staff positions, in advance of the final policy paper.
The :t:ff hn Oc=f dcred b th cf th=: Opti =.
- a. :trictly perf== c bred rule, whil de:ir:ble, i n t dec= d fe n ible at thi ti= bc= =c prob: bili: tic ri:k =:ly i: (PR^) =thod for :hutd=n :=ditic= re not l
=tur =: ugh t: upport devel p=nt f : :trictly perf== : b=ed rule.
i li=cver, th: :t:ff'; ppr=ch i: perf==cc cri=ted in th:t it would
=t:blich cl=r lower li it; for the =:il:bility cf :=ip=nt through techni=1 sp=ifiuti=:; =d :=h limit: := be viewed
= :t=d rd: fr perf = =ce.
In d = cleping it: ppr;=h, th: :t:ff h n put ::ph n b en
- =uring th:t reli:ble :y te= r provided =d that defc=c in depth i: well nrved by all=ing ::=ideration for n= =fety = ucll = cafety--systems-te meet perf=== :t=dard;.
rafperf rmance,e6 _ase.d. n.l,eit n dd..
nlnn n - _ d Th.ntaffndndeve.lopi_ng,ks]Moweveg Tthe staff"b'dTiiWs~a7?By risk n
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'nu.m.er_ical performance goal wd5Td'be~ difficult to 15_13 sis.t9 deriv: :t thi:
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t+mer During low-power and shutdown operations, lant conditions vary 1
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! significantly including water levels in the reactor coolant system, decay heat i
a result, any y b6iab}1 HfR M s @ iessme g {,. and the containment status.PRA levels, availability of mitigation eguiyment As h
to support a numerical performance b=cd rule goal would be more complex than that used to a.+u4mA%ne.v.+$ssess risks at power.
In additi..mM4on, operator actions are M
3 necessary to mitigate accidents initiated during shutdown and low-power conditions. T6fisshtVis'tifillh3thi~siFF6fTidTosiffEfiifh ii!M chTiFi f
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n y will..ex s s in estima ing th.e potential outco.-.mes of t ese operator actions in a"hsid6fid PRA model. However, PRAs are useful to identify the more significi^nt~pTI6t conditions and evaluate the relative risk significance of equipment availabilities. They have been used in the regulatory analysis documented in SECY-93-190.
_In_recogn_it_io.n o._f t_he_limi.tati = cf PPA : del: 'Tff~lE.UTIfis ' $T_s.isifl.Ai.
iiT the staff will develdop a rul~e~wh
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numerical?perfdmancelgoal ocuses on E5?iEtiiEi 6EiTHElluf@Ei,:y:tc= n=ded i =tisfy Ehe critical safety functions yhT_E_ hiss.i_ff_b_is_fis_fii_d. r;ther thu = cverill== rial reliability
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for :hutdown conditions. This approach avoids the complications of establishing numerical criteriaSand the large uncertainties in estimates of i
reliability, especially for humans who are essential in mitigating accidents during shutdown operations. licwever, we will :llcw for ficxibility in the rule = king for acccmpli:hing the required =fety f=ction:. We anticipate I
that the rule will require an outage planning process similar to the high level goals outlined in NUMARC 91-06, " Guidelines for Industry Action to Assess Shutdown Management." We will establish broad requirements in this rule for redundancy of systems providing key safety functions (e.g., decay heat removal and inventory addition) when in shutdown operation. The specific equipment to be used to achieve this redundancy will not be s.pecif.mied in the
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for=' treat =nt through the rule = king prccc= i: ppropriate in the 'eng 3
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accepted and ad ted by licensees, we have developed model technical a P P
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groups and have ni scuss ons with these groups to develop a mutually acceptable set o.
technical specifications.
. Lh,r-L e.w L ed.3 d w.,
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Executive Director t4.
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4, for Operations L f%T%o lebd Pf' cc:
The Chairman Commissioner Remick