ML19257B419
| ML19257B419 | |
| Person / Time | |
|---|---|
| Issue date: | 10/17/1979 |
| From: | Harold Denton Office of Nuclear Reactor Regulation |
| To: | AFFILIATION NOT ASSIGNED |
| Shared Package | |
| ML19257B418 | List: |
| References | |
| REF-GTECI-A-09, REF-GTECI-SY, TASK-A-09, TASK-A-9, TASK-OR NUDOCS 8001160106 | |
| Download: ML19257B419 (3) | |
Text
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[ E alcg'o UNIT ED s1 ATEs
! \\* 3.,, ?g NUCLEAR REGULATORY COMMISSION g
WASHINGTON, D. C. 20555
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OCT 171979 t
.,-.3 Gentlemen:
This past March, the NRC transmitted to you a copy of Volume 3 of fiUREG-0460,
" Anticipated Transients Without Scram for Light Water Reactors" (AT; S) cr.d c copy of an fiRC letter that was sent this past February to each of the four nuclear reactor vendors.
The letters to the vendors contained requests fcr information needed to perform generic analyses related to ATWS.
As we pointed out in our March letters, the generic analyses we requested were intended to confirm that the modifications proposed by the fiRC staff for various classes of LWR designs would in fact accomplish the degree of We ATWS prevention and mitigation described by the staff in its report.
also pointed out that we had chosen to work directly with the vendors in obtaining this information in an effort to conserve both NRC and industry We requested that utilities cooperate with the vendors in per-resources.
forming the requested analyses.
Shortly after sending the letters to the vendors, the NRC Staff mat iith representatives of each of the NSSS vendors and many Utility represer.ta-tives in Bethesda on March 1, 1979.
The meeting was called to discuss the "early verification" approach in which we planned to use generic analyses as the basis for rulemaking.
We hoped thereby to avoid costly and unneces-sary repetitive analysis for individual plants. At the meeting, a tenta-tive schedule was agreed to for generic analyses for each class of plants to be provided in three separate packages'to be submitted May 1, September 1, and December 1,1979.
1750 216 8001160lQ.f e
OCT 171979 Immediately following the March 1 meeting, the NRC staff met separately with each of the NSSS vendors and agreements were made as to the minimum informa-tion to be supplied in the May 1 package. Also, as noted above, copies of the ATWS staff report and the generic analyses questions were transmitted to tie Utilities.
On March 28, 1979 the Three Mile Island accident occurre.1.
Because of the heavy experyfiture of NRC resources required for Three Mile It, lend related activities,
.-.3 essentially no staff effort was applied to the ATWS issue for three months or so following the accident. There was also a substantial reduction in effort on the part of the PWR industry during that period, and some reduction for BWRs.
In June,1979, the NRC Office of Nuclear Reactor Regulation was temporarily reorganized.
Within this interim organization a group was assgned under the direction of S. Hanauer to work on the 19 Unresolved Safety Issues as designat-ed by the Commission and reported to Congress this past January in NUREG-0510.
ATWS is one of these 19 issues.
A preliminary NRR Staff review suggested that, for PWRs, the Three Mile Island accident raised new questions with regard to the appropriateness and adequacy of the resolution of ATWS as proposed by the Staff in Volume 3 of NUREG-0460.
For BWRs, the staff has concluded that the technical impact of Three Mile Island was minimal and that the completion and review of the generic analyses for BWRs as specified in March should proceed as exped'tiously as possible.
A meeting was held in Bethesda on July 25, 1979 to discuss, with representa-tives of PWR utilities and designers, considerations arising from the Three Mile Island accident that might be relevant to ATWS. For your information, a copy of the staff minutes of that meeting is attached as Enclosure 1.
As can be seen from the minutes, at the meeting the staff:
a) Reiterated that ATWS is still believed by the staff to be a serious safety concern and that future protection should be provided.
We stated that we are unwilling to wait another year to make progress on ATWS.
b) Expressed some general and specific technical concerns raised by the Three Mile Island accident with regard to the ATWS resolution pro-posed in Volume 3 of NUREG-0460, c) Asked the industry to provide in writing, within 30 days of the meeting date, its preliminary assessment of the Three Mile Island impact on ATWS, the scope of effort now foreseen to resolve TMI is.;ues, and a realistic schedule for providing the needed ATWS information.
This would include both the March request and the TMI-related analyses.
1750 217
OCT 171979 Subsequent to the July 25 meeting, we have met with representatives of the four NSSS vendors and of some Utility /0wners. We have met with GE to discuss the scope of the remaining generic analysis information to be supplied for BWR 4/5/6's. We have also met with representatives of the GE BWR/3 Diners B&W, B&W:ATWS Owners Group, W,' W ATWS Owners Group, and CE, At all these meetings, we tonsidered further tfie iequirrd information and the schedule for its sub-mittal.
We have now received letters (see the list in Enclosure 2, attached) from the
- various, groups describing the infomation to be furnished and projected schedules.
On the basis of our review of these letters and meetings with the industry representatives, we perceive that the projected responses in several cases would not address several questions in our February 15 letter, In particular, several items are lacking that we will need to justify acceptance of the hardware approaches of NUREG 0460 Vol 3 rather than using the design basis accident approach, I am determined to submit a proposed ATWS rule to the Comission for both PWRs and BWRs early in 1980. The type and content of the rule we will propose will depend critically upon the types and content of the information available to the staff. This will, of course, include whatever responses are actually pro-vided by the industry in response to the questions attached to the February 15 staff letter, the March meetings, and the Three Mile Island related concerns as discussed in the July 25 and subsequent meetings.
I still believe that it is possible for the early verification generic analysis program to provide an acceptable resolution of the ATWS issue and that this is the way to achieve resolution with the least possible expenditure of NRC and industry resources.
However, I want to reiterate that the success of this approach depends on whether or not all of the infomation necessary for the staff to confim that its proposed ATWS modifications provide an acceptable level of protection, for all plants, is provided by the industry.
I strongly encourage you to join or fom Utility /0wners Groups, if you have not already done so, and provide the resources necessary to supply the needed tech-nical information pertaining to your plants, either operating or under construc-tion.
It would further reduce the impact on the industry as well as the staff resources if the ATWS effort coordination and the review role is performed by one industry group, If you have additional questions on the generic analysis'early verification program discussed in this letter, p. lease contact Mr. Ashok Thadani, (301-492-7341).
Sin ly,
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H. R. Denton, Dl rector v Office of Nuclear Reactor Regulatio
Enclosures:
1.
NRC-Industry ATWS Meeting Summary dtd 7/25/79 2.
List of letters from Industry on Content of Report Submittals