ML20148K080
| ML20148K080 | |
| Person / Time | |
|---|---|
| Issue date: | 04/16/1986 |
| From: | Conran J NRC OFFICE OF THE EXECUTIVE DIRECTOR FOR OPERATIONS (EDO) |
| To: | Bernero R, Cunningham R, Jordan E NRC OFFICE OF INSPECTION & ENFORCEMENT (IE), NRC OFFICE OF NUCLEAR MATERIAL SAFETY & SAFEGUARDS (NMSS), Office of Nuclear Reactor Regulation |
| Shared Package | |
| ML20148K054 | List: |
| References | |
| FOIA-87-714, RTR-NUREG-0313, RTR-NUREG-313 NUDOCS 8803310005 | |
| Download: ML20148K080 (9) | |
Text
- q sk:
.!eneuq'o, ,
UNITED STATES
[ e NUCLEAR REGULATORY COMMISSION t, j numrow. o. c. rm.
APR 161986 0%....../
MEMORANDUM FOR: Robert Bernero, NRR Edward Jordan, IE Richard Cunningham, NMSS Denwood Ross, RES '
Clemens Heltemes, AE00 Joseph Scinto, ELO THRU: Robert A. Capra, Acting Director Regional Operations and Gereric Requirements Staff .
FROM: James H. Conran, Senior Program Manager Regional Operations and Generic Requirements Staff ,
i
SUBJECT:
SUMMARY
AND ISSUE IDENTIFICATION FOR CRGR ;
MEETING NO. 89 ;
1 Enclosed for your information and use is the ROGR staff sunnary associated '
I with the long-range approach for dealing with stress corrosion cracking in BWR piping, Draft NUREG-0313 Revision 2. ]
This matter is scheduled for CRGR review at Meeting No. 89 on Wednesday, April 16, 1986 in Room 6507 MNBB, b
James H. Conran ROGR Staff
Enclosure:
As stated cc: J. Sniezek 8803310005 880324 PDR FOIA WEISS87-714 PDR
SUMMARY
AND ISSUE IDENTIFICATION FOR CRGR REVIEW ITEM MEETING NO. 89
~
APRIL 16, 1986 IDENTIFICATI01 NRC Staff long-range Approach for Dealing With Stress Corrosion Cracking in BWR Piping, Draft NUREG-0313, Revision 2, (Staff Positions) and Draf t Generic Letter (Proposed Implementation Vehicle).
OBJECTIVE CRGR is requested to review and recomend in favor of issuing for public coninent (a) proposed Revision 2 of NUREG-0313, which sets forth the staff's technical positions regarding the long-range approach for dealing with the intergranular stress corrosion cracking (IGSCC) of stainless steel piping in BWRs, and (b) a proposed generic letter for implementing the technical
'ositions set forth in that NUREG revision. l BACKGROUND
- 1. The documents package initially submitted by the sponsoring office (NRR) for CRGR review wts transmitted by memorandum dated February 13, 1986, H. R. Denton to J. H. Sniezek; that package included the following:
- a. Draf t Revision 2 to NUREG-0313, dated September 1985, "Technical Report on Material Selection and Processing Guidelines for BWR Coolant Pressure Boundary Piping "
- b. Draft Generic Letter, undated, "NRC Position on IGSCC in BWR Austenitic Stainless Steel Piping," (addressed to all licensees of operating BWRs, applicants for Ols and BWRs, and Holders of cps for BWRs).
- 2. Memorandum dated March 5,1986, J. H. Sniezek to H. R. Denton (Identified additional information required for CRGR review, e.g., a regulatory analysis).
- 3. Memorandum dated April 9,1986, H. R. Denton to J. H. Sniezek (Provided additional infonnation required for CRGR review, including a regulatory analysis and a modified implementing Generic Letter). ,
- 4. Other ,
I
- a. NUREG-1061, Volume 1, dated August 1984, "Report of the U.S. NRC Piping Review Cocinittee - Investigation and Evaluation of Stress Corrosion Cracking in Piping of Boiling Water Reactor Plants."
- b. Minutes of CRGR Meeting No. 45, dated August 22,2983,(seeexcerpt attached).
- c. Amendnent to 10 CFR 50 Part 50.54 and Part 50.109 (see attached excerpt from FRN dated September 20,1095).
DISCUSSION Revision 2 to NUREG-0313 provides licensees a wider spectrum of acceptable alternatives than was previously available for meeting the intent of the regulations. It reflects the relevant reconmendations of the Piping Review 1 Comittee, established by the E00 in 1983 to review comprehensively nuclear piping issues (including IGSCC). Revisien 2 updates and supersedes the technical positions set forth in earlier versions of NUREG-0313 published in July 1977 and July 1980 reflecting the staff's evolving understanding of the nature and scope of the IGSCC problem. As described in the D' aft NUREG, and in j the Draft Generic Letter and regulatory analysis accompanying it in the review package, the staff's preferred approach for mitigating IGSCC in BWRs is still restoration of degraded piping by replacement with more resistant materials; but the staff positions stated in Revisien 2 to NUREG-0313.recoonize the condition of piping as it now exists, and takes into account state-of-the-art knowledge that has resulted from the years of study of this issue.
Accordingly, the positions now proposed by the staff regarding acceptable strategies for long-term resolution of IGSCC would allow a utility greater flexibility in selecting an integrated program that includes options of pipe replacement, repair, stress improvement, water chemistry improvement, and augmented inspections to bring degraded piping into compliance. (Options previously contemplated by the staff included only replacement of degraded piping and augmented inspection schedules for continued interim operation.)
The intended vehicle for actually implementing Revision 2 positions is a Generic Letter inccrporating the essential elements of the NUREG positions.
(See Background item 2).
Yhe regulatory analysis provided by NRR in support of this action (Background Item 3) indicates projected costs in the range $18H/ plant to $130M/ plant and occupational exposures in the range 650 man-rem / plant to 1900 man-rem / plant associated with implementation of the NUREG-0313 Revision 2 positions.
ISSUE
- 1. The new positions contained in NUREG-0313, Rev. 2, which the staff now seeks to igose, qualify as backfitting under the definition established by the Cornission in the new backfit rule, specifically at 10 CFR 50.109(1)(1) (See FRN excerpts attached). The staff has not, however, inade the finding (or even a very strong case) in the package submitted for CRGR review that implementation of the new positions would result in "...a substantial increase iri overall protection of public health and safety... ," and that "...the direct ar,d indirect costs of implementation are justified in view of this increased protection..." as specified in 10 CFR 50.109(a)(3). Further, initially at least, NRR provided no backfit analysis as specified in 10 CFR 50.109(c), nor even the usual regulatory analysis for that matter, in support of the proposed action. This would seem to indicate (although they have not said so
explicitly) that NRR believes the proposed backfitting action qualifies, under the 10 CFR 50.109(a)(4)(i) exclusion, as an action which need not meet the "substantial increase in protection" standard and which requires no backfit analysis (or other regulatory analysis), apparently because of their view that the proposed action involves only modifications ,
...necessary to bring a facility into compliance with a license or the rules or orders of the Comission, or written comitments by the licensee..." This impression is reinforced by NRR's April 9 submittal to CRGR (Background, Item 3) provided in response to ROGR staff coments on l the initial February 23 submittal by NRR. The regulatory analysis included with that submittal notes pointedly that "...we view this proposed action as providing alternatives for complying with, existing regulations, pursuant to 10 CFR 50.50(g)(6)(ii) not to impose new requirements. . ." (emphasis added).
The Ccanittee should pursue these points in the discussions with NRR on this matter. The proposed action may well involve the largest impact (in l terms of total dollar costs to licensees and occupational dose associated with its implementation) of any single regulatory action of its kind ever imposed by NRC. Notwithstanding, NRR appears to be of the view that it I would be perfectly appropriate to create such an unparalled impact without the need for any backfit analysis (or even the usual regulatory analysis),
on the basis of what appears to be a rather selective, out-of-context reading of the 10 CFR 50.109(a)(4)(i) exclusion. Invoking that exclusion seems particularly inappropriate in view of the magnitude of the projected impact, and in further view of the fact that staff's own extensive analyses have failed to demonstrate a clear safety need or sufficient safety / risk benefit to justify the larga expenditures involved. About the strongest conclusion that NRR is able to draw on the basis of the best and latest analysis methods that could be brought to bear on the IGSCC issue by the staff and its consultants, with regard to indicated safety need for, or safety / risk benefit from, the proposed action, is that "...the l presence of IGSCC gma reduce safety margins believed to exist..." and
...without the mitigative actions being taken...public risk could be increased..." (emphasis added). It is also noted that the very favorable cost-benefit ratio calculated by NRR in the regulatory analysis, in going i from NUREG-0313, Rev. I to the proposed NUREG-0313, Rev. 2 positions, is i premised on an assumption that similarly begs the question of justifying l rigorously the transition from the original BWR piping licensing bases to the NUREG-0313, Rev.1 positions.
All in all, NRR's posture and actions in this matter, in trying to "fly" a backfit of this magnitude without a backfit analysis or other appropriate regulatory analysis, on the basis of the 10 CFR 50.109(a)(4)(i) exclusion, seem to reflect a toerious misreading by NRR of the Comission's intent in developing and issuing its backfit rule, and in fact appears to represent nearly the antithesis of the Comission's objectives in that regard.
Appropriate application of this exclusion appears to be a question that has the potential to plague the Comittee's interactions with NRR in many future licensing action proposals if it is not met squarely and dealt with effectively early-on; i .e. , now.
4 l
- 2. Although the main emphasis in in the review package provided t,y NRR for implementing the NUREG-0313 Revision 2 positions appears to be flexibility for licensees in selecting suitable combinations of mitigative measures short of actual replacement of piping as a long-term resolution of IGSCC (if circumstances warrant), another consistent theme which runs through the package is the staff's "preference" (or even strong preference) for replacement of degraded piping to fully restore confidence in its long-term integrity. (See, for example, regulatory analysis at p. 2, 2nd paragraph; regulatory analysis at p. 9; Generic Letter at p. 2, 3rd paragraph; NUREG-0313, Revision 2, Executive Suninary at p. vii, 5th paragraph; Executive Sumary at p. viii, last paragraph; NUREG-0313, Revision 2 at p. 6,1st paragraph of Section 1.5; etc.).
The Comittee should inquire explicitly regarding (a) whether the staff expects to approve, as long-term resolutions in at least some plants, mitigative measures or combinations of measures short of actual replacement of piping, or (b) whether the staff's ultimate aim is replacement of degraded piping, with the mitigative measures specified in Revision 2 treated only as "interim" measures in the long run.
- 3. Addressing the basic cancern alluded to in (2) above from another direction, the Comittee may wish to inquire of the staff why piping replacement is so strongly favored as the long-term resolution of IGSCC, when staff's extensive analyses appear to indicate that individual mitigative measures (or combinations of measures) specified in Revision 2 of the NUREG can provide adequate levels of safety for less total dollar cost and occupational dose comitment; e.g., as in the comparison of Scenario 1 (Piping Replacement Option) and Scenario 2 (IHSI Option with/without improved water chemistry) in Appendix E of NUREG-1061 Volume 1 (Background Item 4.a).
4 The staff uses the terms "requirements," "positions," "staff requirements" and "staff positions" in various contexts and sundry ways that do not always appear to be either internally consistent within the review package itself or consistent with usage of the terms "requirements" and "positions' in the backfit rule and NRC Manual Chapter 0514. In the April 9th letter (Background Item 3), for example, NRR states "...we view this proposed action as providing alternatives for complying with existing regulations, ...not to impose new requirements." In the next paragraph of the same letter, NRR states that the NUREG will be included for reference in the proposed generic letter "...to explain the bases of the "staff requirements." Is "requirements" to be construed equivalent to regulations in the first context and equivalent to positions (i.e. ,
guidance) in the second context?
The Comittee may wish to explore this matter of inconsistent usage with the staff to assure that there is clear understanding of what is intended in this and other confusing contexts in the review package. It may be, for exagle, that the confusion that results from inconsistent usage of these tenns is at the root of the issue addressed in (1) above.
5-i 1
- 5. As a final item, excerpts from the Minutes of CRGR Peeting No. 45 are i attached for the information of the Comittee members, it appears the the l DEDROGR staff treatment of the questions of safety need for, and risk i benefit from, the proposed IGSCC mitigative measures, when the Committee considered these matters several years ago, is still relevant. It may be ;
useful to explore with the staff if in their opinion the picture has changed in ariy significant way in these respects from that portrayed in those earlier Minutes, l
)
l 1
l l
1 I
l l
l t
1 1
n.&.n
~
,,w reur. n ese s u m u. m i m .r.ser.a . m n
.ma .e - = >sEFl 8 eu m m Com o.sha ,e systematic and doewnentedp,abrs6e
,s.
thatceaere de.cr ,,e, e, .e .c,,e,,,
el some soJetu 9 weald be required by he boe
- re'.: :63,s es w.gger,,*,,a; -- - g = = * . m .uw ,,
e u . i . m , ara ,,, m isse e. a io w asie - a s a a o ,e - . ,ote,,a! ,,,,,,,,,,,,
I reed as Anoews paragnph (aX4Xu) of this sect 5cc 'abaB y grg ,g ,g,gy
. - - - A 'm,"ag*a' E, rar,er.e. -g,o,nta d
'- -l,- ~~ e l betere "
e ne % .haD . as,-
do
,,h,)o, en, h ,as ei,acanesa The tate.es, e,,.e Commlasion aban aco.
mquire the u
- *=~> m -
aeste req.at ef*"tion of the Commiusos meam licemen,open a i *"M* bista5
- d *** *e eden w ckni, and written esa tements, etsned user oath or becantting determines, based of a facuity&ggy es the east of lecial y downtisme er the east affirmatles. to enable the Commission to ducrbd la paragraph (c) of af eseeemedan De potentialse delarhety hapact of determine whether or not thencense section. that there le a substaattel should be modified. suspended er ' incna se in the overoD protectice of b . a la plaat er operational -
revoked. Except for taformatles sought public health and ufety er b commoa shy. incladlag the mlationship to to vertfy &censu compliance wth the defense and security to be dartved from proposa and existing regulatory current Econstag basis for thes bcGity. the backht anQhat the direct and M1-the NRC must prepare the reessa or ladirect costs of implementation for ht (7)m estimated resource burden se 4easons for each information sequest fscility are lastifled in view of thu the NRC apodated with the to Isavance to ensun ibenbe Jacreased protection, 9 I eckSt b and be avaAabuity Iur"de w de unnsa on ru,mdents a 4W N provision of paresnphs (e)(2) resources:
Justined ta view of the potensielsafety and (a)(3) of this section are (3) N potendalla pct of egerence, signincaces of 6 issue to be addrecsed inapplicable and. therefore. beckSt in facility type, daign er age se the la b requested information. Inch such* analysis is not recu! red and the relevancy and practicality of the tustlhcation rovided for se eseh4 tion standard den not apply where the staff proposed backht; performed b b NRC staH amas be Ands and declares, with appropriate gel.Whethw b sd bachat le approved b the E.xecutive13 sector for documented evaluation for its RadinS Interia or Baal laterim.the '
Operst6ans or his oc het desipes prior ther: cation for im ing h propeed to iswance of h requeet. (0 Nt a modlBeation is seensary on an ist basis.
. . . . . bring a facility into compilance with a (d) No 11cena u . i - n ,,,re,uans,ewsa.
u=a =
- aa - -*a d e maheid dog % action eae-y wtBof baanibe sph (c) Commlulon. or lato conformance with analyHs mquird by b Cmuma's paragraph (b)la removed, tten commitments by the licenlee. nj,,. ;
is revned new, r.,a and dredestlaww t and muap"gdaalr***
w m e ec., oi,ec,o, ,e, l add = =w a fam
.a ,,
au u ,ec g se , U u .M e o.
e y.
- "a f t**"'"Z. onten> *D e,2';"
- 'a.aun= * *a .~as aw a be r**nwa -
. ',w 6 th a
--(exu anmns is denned.a such docum enied e ,.iuaeo sk a .w se yses
,,o ",J'b , h ,o Lmo ,,a m ,,c,o, l snodi0 cation of or addidos legstems. triclude a statement of the obiectiven af for rations er his designes, i st.uctures.
components. or denly, of a and reasens for the rnodifin'ua and.1ha.
bars 'or inve*
- the me *a 4 I' APpendia 0 to to CFR part sta a facihty; er & dulgn 4pproud er manufacturing licenu Ier a hasty, or (b) Paragtaph ('al of thu section shad new section (8)is added to read a not apply to backfits impond prior to ISO'**;
the proceduns or organ! siisa sequind to design. construct or opersas a falcility October 2't.1983.
(c)In reaching the determh.atios %da 0-Standarelastlee W any of wWeh may tesuh fromanew or amended provision in the Cens.ssion required by paragtsph (a) of this section. Design; Statt Review of Standard Deegne rules g the imposition of a suyastwy the Cenunluton wiD consider how b staff positien laterpretint es backfit should be prioritized and * . . . .
Comunisalon rule: that is etternew or seheduled id Ifght of other regulatory IL hformation requests a 6e appresel diffe ent from a aredovsle enabcahl, aclivith ongoing at the facility and. In beider regarding an opp *ond des:sn sket: be etaff ooamn an~ar. eddition. wiu consider informanoa eva%ated grior to anilable conminns any of the hw*n to w9esed onissuance rupondeets to enivre a itat the
- (s)The dafe ofisnuance of 4, lusured in vww ofibe po:enna! 54fe.y construct.cn permit for the haty for following factors as may be appropriate
[,tQf e sv ar.d any other trJormaUon rtlevant and s sed e facdities hadng construct >osparv.!!s , gd mater al to the ; posed ba evehauon performed by th NRC s'e': sbf1 issued af:er October 21. tem er (ii) Six months before the ese of
() faamut o 6 spuigkfit: e be :n accordanca w.a to CTR so 9m an!
Wuhus that the propesed backfit is sb!! be appres ed by th Eareveu Director docketing of the operatir:gncesse duped to achim-apphcation for the facdity lethetbun for Operanens or his or her dwinu pnu 'o h av.r3 construction permFs humed '58' * * 'It!* ' W **L b fere October 21.1961er 4 " **" **d +'* ** 8 'M " * **'
24 rec. 4,pc,wt %e6,,swee >O n P ARI 3=={ AblENDED)
,tii)The data ofissuanca dte ne ,,% . u3 ,, ,., ,, .. e d to ee,p.".
s cperstins license for the locat be w n wi,c.m,m:wy.cm.% cy w. L N eothenty citat!on for Part 2 f.:!btus havtre operateglicanes.or m *t s*
- M w *% woe = e* h.s h ceousses to read as follows.
(iv) The date of issuan:e dis dulgn **"*"***""****" * * ' " "
a; proval er. der Appendix R3er O of tw mt .'w e w .n. .a u"m er we Andwirr Se s m 1at 64 S:ai su in w .,,, u , , , u ,2 . . n , 3 ,n ,.y . , u r ,.,,,, y g $ e m., a m g. ,
thispaet. sna., n te r.. < ... a ..e s.w . w 24. M. L H-44 *C $. u es t
- - , - - . , - - ~ , - - - - - - -
, ,, ..w.,
. , _ . - --- . ,_,---,.-- .-----., ,_,.,_ ,,,..n,_--.v. n. . - - - - - .
l the ASME Code Class 1 portion of the residual heat removal system piping l and the core spray and react 0r water cleanup system. 1 The Comittee noted that there appeared to be a sense of immediacy l implicit in the staff's proposed shutdown orders. The Committde further 1 noted that the information presented in support of the proposed shut- ,
downs did not reflect a safety rationale either for or against shutdown. l Concerning the safety rationale, the Comnittee had the benefit of l discussions with various RES staff members on the potential safety i impacts of pipe cracks. L. Shao (RES) reported his views and those of '
l Dr. Spencer Bush (consultant) concerning the potential changes in frequency for a severe rupture of large size BWR pipes.. For example, both Mr. Shao and Dr. Bush believe that the frequency of severe gupture5 of uncracked large size BWR piping would be in the range of 10~ - 10" {
per reactor year. Mr. Shao spec 01ated that cracked pipes of the type i now being revealed would increase the rupture frequency by an order of l magnitude. On the other hand, Mr. Shao noted that Dr. Bush believed the rupture frequency would increase by about a factor of three. Concerning the potential risk impacts from all sizes of BWR pipe ruptures, the Comittee was advised by P. Barano.dky (RES) that PRA results revealed such loss of coolant accidents to T.,e very small risk contributors - on the order of a few percent of the total risk. Mr. Baranowsky indicated that an order of magnitude increase in the pipe rupture frequency would still leave the risk contribution at about 10% of the overall risk and would have a similarily small increase in the overall core melt frequency.
The Comittee was advised of an analysis by the DEDROGR staff that confirmed the RES views. The DEDROGR staff used some bounding arguments as to BWR pipe crack and failure experience over approximately 300 reactor years, and explored the potential risk i assumed a pipe rupture (LOCA) frequency of 2X10~gpacts. per reactor year These so analyses as to reflect a 95% percentile level of confidence derived from actual BWR experience where pipe cracking leakage but no severe pipe rupture has occurred. The DEDROGR staff also noted that additional analyses should also provide a good approximation to that wider base of pipe fracture data that suggests that a small fraction (e.g., I to 10%) of all piping failures would be severe (or catastrophicD ruptures. This assumption was also tantamount to assuming that the BWR pipes were at an incipient failure point. On the basis of these analyses, there did not appear to be a strong sense of urgency or an imediate safety concern or danger from the standpoint of public risk. Estimates by the DEDROGR staff suggested that the averted public risk would be less than 100 man-rem /RY. This averted risk would likely range around 10 man-rem per reactor year if the kind of credit given to fission product retention by the suppression pool was the same as that given in the Reactor Safety Study (WASH 1400). Using cost estimates made by TVA for an accelerated shutdown of the Browns Ferry, Unit 3, the DEDROGR staff reported to CRGR that the value/ impact ratio associated with the proposed staff
actions would be about I man-rem /million dollars or These less. results Shao and Dr. Bush due to the pipe cracking. enveloped tN incr .
The Connittee concluded that the staff's safety rationale for the proposed actions was based on a defense-in-depth argument. The concern is that there are not adequate inspection data to provide confidence in the overall integrity of the piping and its leak tightness (the first level of defense-in-depth . There is also concern for the ability to detect incipient failures)because of limitations in leak detec second level of defense-in-depth). Since the defense-in-depth philosophy requires attention to each level of protection as if it were the last, these five plants need early attention.
supported this rationale. The Committee However, the Comittee noted that analyses of the type usually carried out by the staff for purposes of prioritizing its approach precipitous to generic actions in thisissues, matter.would not have supported the need for For example the Committee noted the significant difference in the sense of urgenc,y associated with this matter as compared to that of ATWS, which is expected to have a much larger potential accident risk. Accordingly, the Comittee concluded that the sttff should continue to negotiate with licensees es to the earliest iaspectinns and mostIncost needed. this' effective regard shutdown date to accomodate the piping shutdown intervals of as much as sev,eral months beyond the date o issuance urgency of the or small order risk accident would not be involved. unreasonable in view of the safety conclusion was based solely on safety considerations and that con-The sideration of other economic factors such as those associated with cleanup from a pipe break might lead to a different course of action, such as an accelerated schedule for inspection of the piping.
The Cousittee was particularly concerned with the imediacy of the action proposed for Browns Ferry, Unit 3.
The staff stated that the primary difference between Browns Ferry, Unit 3 and the other plants covered by the proposed orders is that TVA was unable to offer suf-ficient evidence acceptable to the staff to support interim operation.
TVA shutdown.based its entire case on "leak before break" and the impacts of the The staff noted that the licensees for the other affected data for the plants or data from sister plants. units were able to The Committee's concerns were based on (1) the apparent impact of the action as compared
- that the extent of cracking expected to be found in B i would be comparable to others that are being permitted to operate for l
longer periods, (3) the staff's expectation of "leak before break " (4) the compensatory actions that could be taken in the interim period, and (5) the period apparent until November very low accident risk to the public during the short 11, 1983. .
1 i i
I
!i
!