ML19274E660
| ML19274E660 | |
| Person / Time | |
|---|---|
| Site: | Crane  |
| Issue date: | 04/05/1979 |
| From: | Hendrie J NRC COMMISSION (OCM) |
| To: | Ellen Brown CALIFORNIA, STATE OF |
| References | |
| NUDOCS 7904170105 | |
| Download: ML19274E660 (5) | |
Text
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WASHINGTON. D. C. 20555 v.N'/.%,[.
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' Aprkl 5,1979 CHAIRMAN
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The Honorable Edmund G.
Brown, Jr.
Governor of Califorr.ia Sacramento, California 95813
Dear Governor Brown:
I am responding to your telegrau, which requested a precautionary and temporary closing of the Rancho Seco Nuclear Power Plant following the incident at the Three Mile Island Plant in Pennsylvania.
h Our staff has reached preliminary conclusions concerning the principal factors which initiated the accident and contributed to its severity.
These were discussed yesterday in an open Commission meeting and a list is enclosed.
We have taken or are taking the following specific actions with regard to nuclear plants similar to Three Mile Island, that is, plants having Babcock and Wilcox pressurized. water reactors, including Rancho Seco:
An inspector was assigned full-time at each operating plant having a B&W reactor by April 2.
The inspector at Rancho Seco was on-site beginning March 31, 1979'at 4:45 P.M.
An NRC Inspection and Enforcement Bulletin (enclosed) was transmitted'on April 1 directing licensees' operating B&W reactors to perform a series of specificireviews and actions.
The licensees must respond by April 11.
Our on-site inspectors will monitor compliance with this bulletin.
The NRC headquarters staff will review the responses promptly and act on them accordingly.
A second Inspection and Enforcement Bulletin is being prepared and will be transmitted immediately to provide specific operating instructions based on our present understanding of the events at Three Mile Island.
A copy will be forwarded to you.
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To assure that the Bulletins are fully understood and followed, the full-time inspector at each of the operating plants having B&W reactors, including Rancho Seco, will receive additional' assistance from the NRC regional offices to assure that some inspection activities will occur during each shift.
The assigned inspector at the Rancho Seco Plant will thus be in a position to assure that plant operations on all shifts reflect a clear awareness of the factors which contributed to the situation at Three Mile Island.
The NRC regional and headquarters staffs will stay in close touch with the NRC inspectors on site to ensure that our instructions to the licensees are understood and are being followed.
The Commission is sending a telegram (attached) to each of the concerned licensees to underscore the seriousness with which the Commission views this situation.
gg Additionally, an NRC Task Force on Generic Review of Feedwater Transients in B&W Reactors has been formed to examine the reactor and plant systems at these plants that provide protection against feedwater transients.
The Task Force report is expected before-the end of this month.
We will carefully review that information and take whatever further action may be appropriate.
Pending completion of our review of the responses to the April 1st Bulletin and in view of the actions described above, we believe there is reasonable assurance the plants can continue to operate without danger to the public health and safety.
Although Commissioner Bradford agrees fully that the aforementioned specific procedures are prudent and provide a considerably enhanced level of assurance, he would await the report of this Task Force before sharing fully in this conclusion.
We have asked the Director of our Regional Office in Walnut Creek, Mr. Robert H. Engelken, to keep in close touch with your office to keep you advised of matters as they progress.
As soon as our analysis is completed, we will be in touch again to apprise you of the results.
incerely,,
s ph M. Hendrie y~
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Chairman
Enclosures:
1.
List
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2.
Bulletin 3.
Telegram
MAJOR FACTORS CONTRIBUTING TO THE i
THREE MILE ISLAND' ACCIDENT (PRELIMINARY ANALYSIS)
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1.
At the time the events leading to the accident began, all three auxiliary feedwater pumps in the plant's secondary cooling system (which carries steam to the turbines that drive the electrical generators) were valved off, making the system inoperative.
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2.
e The relief valve on the pressurizer in the primar;'
coolant system, which was automatically opened to relieve excessive pressure in the primary system, failed to close after pressure was relieved.
3.
Instruments indicating the level of coolant in the pressurizer apparently gave erroneous readings.
4.
The containment was not isolated at the time the emergency core cooling system (ECCS) was activated.
5.
The ECCS appears to have been turned off prematurely.
6.
Tripping of the reactor coolant pumps increased damage to the reactor core.
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APRIL 5, 1979 TELEGRAM TO B&W LICENSEES THE COMMISSION'S DIRECTOR OF INSPECTION AND ENFORCEMENT HAS ISSUED A BULLETIN DATED APRIL 1, 1979, AND IS ISSUING A SECOND BULLETIN THIS EVENING TO ALL LICENSEES OF NUCLEAR POWER PLANTS INCORPORATING STEAM SUPPLY SYSTEM DESIGNS ESSENTIALLY IDENTICAL TO THAT OF UNIT NO. 2 OF THE THREE MILE ISLAND FACILITY.
THESE BULLETINS DIRECT THE LICENSEES TO FOLLOW CERTAIN PROCEDURES AND DEVELOP PARTICULAR INFORMATION IN CONNECTION WITH PROTECTING AGAINST EVENTS SIMILAR TO THOSE AT THREE MILE ISLAND.
THE PURPOSE OF THIS MESSAGE IS TO UNDERGCORE THE SERIOUSNESS WITH WHICH THE COMMISSION VIEWS THESE MATTERS AND THE IMPORTANCE WE ATTACH TO YOUR PROMPT AND COMPLETE COMPLIANCE WITH THE DIRECTOR'S BULLETINS.
WE TRUST THAT YOU WILL EXERT YOUR BEST EFFORTS TO COMPLY WITH THE AFOREMENTIONED DIRECTOR'S BULLETINS COMPLETELY AND IN A TIMELY FASHION.
TO THAT END, WE EXPECT THAT YOU WILL ASSIGN TO THESE TASKS AMPLE PERSONNEL, SUPPORTING SERVICES, AND ANY OTHER NECESSARY RESOURCES.
JOSEPH M.
HENDRIE CHAIRMAN v.
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ADDRESSEE 5:
Toledo Edison Company Edison Plaza 300 Madison Ave.
Toledo, Ohio 43652 Florida Power Corporation 3201 34th St. South St. Petersburg, Fla_.
33733 Duke Power Company 422 S. Church St.
Charlotte, N. C.
28242 Sacramanto Municipal Utility District 6201 South St.
Sacramento, Calif.
15830 Arkansas Power & Light Co.
9th St. at Louisiana Little Rock, Ark.
72203 Metropolitan Edison Company 2800 Pottsville Pike Reading, PA.
19640
.