ML19312E481
| ML19312E481 | |
| Person / Time | |
|---|---|
| Issue date: | 04/03/1980 |
| From: | Chilk S NRC OFFICE OF THE SECRETARY (SECY) |
| To: | Dircks W NRC OFFICE OF THE EXECUTIVE DIRECTOR FOR OPERATIONS (EDO) |
| Shared Package | |
| ML19312E480 | List: |
| References | |
| NUDOCS 8006040511 | |
| Download: ML19312E481 (3) | |
Text
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.G. = *; 7 i C3,s-MElGTANDUM FOR:
Wihiam Dircks, Acting EDO
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FROM:
Samdel J. Chilk. Secretary
SUBJECT:
STAFF PEQUIAEMENTS - DISCUSSION OF SECY-107 -
PROPOSED INTERIM HYDROGEN CONTROL REQUIREMENTS FOR SPALL CONTAINMENTS, 2:05 P.M.
WEONESDAY, PARCH 19, 1980, COMMISSIONERS' CONFERENCE ROOM. D.C. OFFICE (OPEN TO PUBLIC ATTENDANCE)
The Comission discussed the need for interim hydrogen control 1.
requirements for srall containments, and the proposed inerting of all Mark I and Mark II containments for boiling water reactors. The Commission took no final action, but requested that:
the identity of the contractor who performed the calculations a,
of containment capability to accommodate hydrogen generation from metal water reaction. and a copy of the contractor's anal ve 4e, h av ind.
(nRR) (Sen L;per-
~4/31/80) a list ofplants whose containment types fall within the
[
b.
following categories:
Mark I, Mark II, Ice Condenser, Park III, subatmospheric, and Dry Containment.
(NRR) (Secy Suspense:
3/31/80) w.w i hun or the experience with dryk11 entries into c.
containment in an inerted plant, with the information provided c
by officials of Vermont Yankee, a non-inerted plant, during the r.eeting'.
(NRR) (Secy Suspense: 4/8/80) d.
further consideration be given to the views of the Probabilistic Assessment Staff regarding the relationship of inerting to reduction of overall safety risks, and to an overall approach which would delay the proposed imediately effective interim actions on hydrogen management in containments while expediting the degraded core cooling rule so that hydrogen control can be evaluated in a broader context of all accident and safety system design bases.
(NRR) (Secy Suspense:
4/16/80)
The Comission also requested that the views of the General Electric 2.
Company on the utility of inerting, including any calculations which differ from those provided by the NRC staff, be provided in writing.
(
ENCLOSURE BSt@$'
s BACKGROUND-The accident at Three Mile Island, Unit 2 involved'a large amount of metal-water reaction in the core with resulting hydrogen ceneration well in excess of the amounts specified in 10 CFR Part 50.44 of the Commission's regulations.
A rule-making proceeding on the subject of' degraded cores and hydrogen management is under consideration by the Commission.
This proceeding is suggested in item II.B.8 of the "NRC Action Plans Developed as a Result of the TMI-2 Accident," Draft 2, NUREG-0660, January 23, 1980.
In a February 22, 1980 memorandum from Mr. Denton to the Commissioners, the staff recommended interim hydrogen control requirements that included inerting of all Mark I and Mark II containne its.
In response to this recommendation, the Commis-sioners have asked for background information on plant entries into inerted con-tainments.
Vermont Yankee, a non-inerted plant, has supplied the staff with a summary of all unscheduled entries into the drywell volume for the last five years.
By complet-ing the attached request for additional information, the staff will be able to report to the Comnission the diverse reasons for entering the drywell volume along with the advantages and disadvantages of inerting. The Commission will consider this information in reaching its decision on the proposed hydrogen control re-qui remen ts.
In order for the staff to meet the Commissioners' schedule, we would appreciate receiving all responses by April 3,1980.
ENCLOSURE 4
e.
Request for Additional Information 1.
Provide a tabulation of the following information pertainino to unscheduled entrie.s of the drywell volume for the time period 1/1/75 to the present; (a)
Date of entry (b) reason for entry (for RCS leakage describe the size of the leak in GPM end % of operating limit)
(c) duration of plant shutdown for entry (d) result of entry (describe the fix)
(e) any additional remarks which would aid in determining the nature of the cause for entry and the result (i.e., for an RCS leak identify the the time at which leakage was first detected and the time at which the containment entry was initiated.)
2.
Describe orovisions which you have employed or have considered, to detect and reduce RCS leakage without entry.
For example, are TV cameras employed to detect or locate valve packing leaks, which may be reduced by remotely cycling the valve against its backseat?
3.
Provide a general description of your past experience with RCS leakage, in-cluding comparison to technical specification operating limits.
Identify any time periods for which the plant has been operated with RCS leakage in the containment substantially lower than the Technical Specification oper-ating limit until a scheduled entry.
ENCLOSURE l
4