ML19347D127
| ML19347D127 | |
| Person / Time | |
|---|---|
| Issue date: | 02/20/1981 |
| From: | Ahearne J NRC COMMISSION (OCM) |
| To: | Udall M HOUSE OF REP., INTERIOR & INSULAR AFFAIRS |
| Shared Package | |
| ML19347D128 | List: |
| References | |
| NUDOCS 8103110119 | |
| Download: ML19347D127 (1) | |
Text
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UNITED STATES 3*
j NUCLEAR REGULATORY COMMISSION J
W ASH tNGTON, D.C. 20555 COMMISSION
%... * '6 CORRESPONDD 3 February 20, 1981 OFFICE OF THE CHAtRMAN e
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The Honorable Morris K. Udall, Chairman MAR 0'J1981 A '/
Subcommittee on Energy and the Environment D " gawon h Committee on Interior and Insular Affairs United States House of Representatives is ff Washington, D.C.
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Dear Mr. Chairman:
In a letter to you dated January 9,1981, we provided a copy of the staff safety evaluation on the BWR Scram Discharge System.
The report contained, among other things, reconinended actions for both near term and long term implementation.
In order to keep you informed of actions taken which were based on the report, we are enclosing a copy of a January 9, 1981 order which is typical of those sent to the affected BWR licensees and a staff supplement to the original safety evaluation.
The order requires that an automatic system for inserting control rods on low instrument air pressure in the control air header be operable by April 9,1981.
The supplement dated January 12, 1981 provides an evaluation of continued reactor operation for several months while the order modifications are being implemented.
We concluded that there was no undue risk in continued reactor operation while the short term modifications are being made.
We will keep you informed of the long term actions we take based on the BWR Scram Discharge Safety Evaluation.
Sinc ely,
(
John F. Ahearne l
Chairman
Enclosures:
1.
Order dtd 1/9/81 2.
BWR Scram Discharge System Safety Evaluation-Supplement 1 cc: The Honorable Manuel Lujan 8108130//i-
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'A NUCLEAR REGULATORY COMMISSION e
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,*%WMY s I3st Docket No. 50-263 Mr. L. O. Mayer, Manager Nuclear Support Services Northern States Power Cowany 414 Nicollet Mall - 8th Floor Minneapolis, Minnesota 55401
Dear Mr. Maye'r:
SUBJECTI ORDER FOR MODIFICATION OF LICENSE CONCERNING BWR SCRAM DISCHARGE SYSTEMS This letter transmits an Order for Modification of License which requires pro:pt implemntstion of certain actions to assure the safe operation of BWR's with inadequate Scram Discharge Volume - Instrument Volume (SDV-IV) hydraulic coupling.
The licensee should, to the extent practical, design the Automatic Dump System to be independent of the l
air pressure instrumentation for manual scram.
A copy of the Order is being filed with the Office 'of the Federal Register for publication.
Sincerely, l
l
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Thoma
. Ippolito, Chief Operating Reactors Branch #2 Division of Licensing
Enclosure:
order cc w/ enc 1:
See next page
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v UNITED STATES OF Au. ERICA NUCLEAR REGULATORY CONV.ISSION In the Matter of NORTHERN STATES POWER COMPANY Do:ket No. 50-263 (Monticello Nuclear Generating Plant)
ORDER FOR MODIFICATION OF LICENSE I.
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The Northern Sta' es Power'Conparty (licensee) is the holder of t
Provisional Operating License No. DPR-22 which authorizes the operation of the Monticello Nuclear Generating Plant, at steady state reactor pcwer levels not in excess of 1670 megawatts thermal (rated pwer).
The facility consists of a boiling water reactor located at the licensee's site in Wright County, Minnesota.
II.
During a routine shutdown of Browns Ferry Unit No. 3 on June 28, 1980, 76 of 185 control rods failed to fullycinsert in response to a manual scram from approximately 30% power.
All rods were subsequently inserted within 15 minutes and no reactor damage or hazard to the public occurred.
- However, the event did cause an in-depth review of the current BWR Control Rod Drive Systems which indentified design deficiencies requiring both short and long-term corrective measunts.
These measures are set forth in the Generic Safety Evaluation Report - BWR SCRAM DISCHARGE SYSTEM, dated December 1,1980, prepared by the NRC staff.
One of the deficiencies identified was a failure
- mode of the control air system, whicti can conceivably cause an inability to scram 3~'[M60t(Q gic