ML19326A980
| ML19326A980 | |
| Person / Time | |
|---|---|
| Site: | Crane, Davis Besse  |
| Issue date: | 05/16/1979 |
| From: | Chilk S NRC OFFICE OF THE SECRETARY (SECY) |
| To: | NRC COMMISSION (OCM) |
| References | |
| NUDOCS 8003050913 | |
| Download: ML19326A980 (11) | |
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UNITED STATES OF AMERICA egg) 7jg79 > ;9 NI' CLEAR PIGULAICRY CCMMISSICN 7
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'n1E 'IOLEDO EDISCN CCMPANY AND
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' HIE CLrVEIRO ELECIRIC ILLUMINATING
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Docket No. 50-346 CCMPANY
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Davis-Besse Nuclear Power Station,
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Unit No. 1
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ORDER SIN]4 The Toledo Edison Company (TECO) and The Cleveland Electric Illuminating Company (the licensees), are tolders of Facility Operating License No.
NPF-3 which authorizes the operation of the nuclear power reactor known as Davis-3 esse Nuclear Power Station, Unit No.1 (the facility or Davis-Besse 1), at steady state power levels not in excess of 2772 megawatts thermal (rated power). 'Ihe facility is a Babcock & Wilcox (B&W) designed pressurized water reactor (WR) located at the licensees' site in Ottawa County, Ohio.
II.
In the course of its evaluation to date of the accident at the 'Ihree Mile Island Unit No. 2 facility, which utilizes a B&W designed NR, the Nuclear Regulatory Comission staff has ascertained that B&W designed C
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7590-01 reactors appear to be unusually sensitive to certain off-normal transient conditions originating in the secondary system.
We features of the B&W design that contribute to this sensitivity are:
(1) design of the steam generators to operate with relatively small liquid volumes in the second-ary side; (2) the lack of direct initiation of reactor trip upon the occur-rence of off-nonnal conditions in the feedwater system; (3) reliance on an integrated control system (ICS) to automatically regulate feedwater flow; (4) actuation before reactor trip of a pilot-operated relief valve on the primary system pressurizer (which, if the valve sticks open, can aggravate the event); and (5) a low steam generator elevation (relative to the reactor vessel) which provides a smaller driving head for natural circulation.*
l Because of these features, B&W designed reactors place more reliance on the reliability and performance characteristics of the auxiliary feed-water system, the ICS, and the emergency core coolirg system (ECCS) per-formance to recover from frequent anticipated transients, such as loss of offsite power and loss of normal feedwater, than do other PWR designs.
21s, in turn, places a large burden on the plant operators in the event of off-normal system behavior during such anticipated transients.
- It is noted that although features numbers 3 and 5 do not apply to Davis-Besse 1 to the same extent as they apply to other currently licensed B&W designed reactors, the other features are fully appli-cable.
s 7590-01 As a result of a preliminary review of the Three Mile Island Unit No.
2 accident chronology, the lac staff initially identified several human errors that occurred during the accident and centributed significantly to its severity. All holders of operating licenses were subsecuently instructed to take a nu :ber of imediate actions to avoid repetition of these errors, in accordance with bulletins issued by the Commission's Office of Inspection and Enforcement (IE).
In addition, the NRC staff began an ic:nediate reevaluation of the design features of B&W reactors to determine whether additional safety corrections or improvements were necessary with resrect to these reactors. This evaluation involved numerous meetings with B&W and certain of the affected licensees.
The evaluation identified design features as discussed above which indicated that B&W designed reactors are unusually sensitive to certain off-normal transient conditiens originating in the secondary system.
As a result, an additienal bulletin was issued by IE which instructed holders of operating licenses for B&W reactors to take further actions, including ictediate changes to decrease the reactor high pressure trip point and increase the pressurizer pilot-operated relief valve setting.
Also, as a result of this evaluation, the lac staff identified certain other safety concerns that warranted additional short-term design and procedural changes at cperating facilities having S&W designed reactors.
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7590-01 j.
These were identified as items (a) through (e) on age 1-7 of the Office of Nuclear Reactor Regulation Status Report to the Commission of April 25, 1979.
After a series of discussions between the NRC staff and the licensees concerning possible design modifications and changes in operating pro-cedures, the licensees agreed in letters dated April 27 and May 4,1979, to implement promptly the following actions:
(a)
Review all aspects of the safety grade auxiliary feedwater system to further upgrade components for added reliability and performance.
Present modifications will include the addition of dynamic braking cn the auxiliary feedpump turbine speed changer and provision of means for control room verification of the auxiliary feedwater flow to the steam generators. 21s means of verification will be provided for one steam generator prior to startup from te present maintenance outage and for the other steam gene,rator as soon as vendor-cupplied equipnent is available (estimated date is June 1, 1979).
In addition, the licensees will review and verify the adequacy of the auxiliary feedwater system capacity.
1 (b)
Revise operating procedures as necessary to eliminate the option of using the Integrated Control System as a backup means for controlling auxiliary feedwater flow.
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7590. (c) Imple.ent a hard-wired control-grade reactor trip that would be actuated on loss of main feedwater and/or turbine trip.
(d) Complete aralyses for potential sr.all breaks and develop and implement operatirg instructions to define operator action.
(e) All licensed reactor operators and senior reactor operators will have completed the Three Mile Island Unit No. 2 simulator training at B&W.
(f) Suhait a reevaluation of the TECO analysis of the need for automatic or administrative control of steam generator level setpoin*a during auxiliary feedwater system operation, previously submitted by TECO letter of Deceber 22, 1978, in light of the tree Mile Islam Unit No. 2 incident.
(g) sum.it a review of the previous TECO evaluation of the September 24, 1977 event involving equipnent problems and depress-urization of the primary system at Davis-Besse 1 in light of the 2ree Mile Island Unit No. 2 incident.
In its letters the licensees also stated that the actions listed in (a) throu;;h (g) above would, except as roted in item (a), be completed prior to s*artup frem the current reintenance outage.
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7590-01
. In addition to these nodifications to be implemented promptly, the licensees have also proposed to carry out certain additional long-term modifications to further enhance the capability and reliability of the reactor to re-spend to various transient events.
Rese are:
- We licensees will continue to review performance of the auxiliary feed-water system for assurance of reliability and performance.
- he licensees will submit a failure mode and effects analysis of the ICS to the NRC staff as soon as practicable.
W e licensees stated that this analysis is now underway with high priority by B&W.
- We reactor trip following loss of main feedwater and/or trip of the turbine to be installed promptly pursuant to this Order will thereafter be upgraded so that the components are safety grade.
We licensees will submit this design to the NRC staff for review.
- Continued attention will be given to transient analysis and procedures for management of small breaks.
- he licensees will continue reactor operator training and drillirs of response procedures to assure a high state of preparedness.
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7-The Comission has concluded that the prompt actions set forth as (a) through (g) above are necessary to provide added reliability to the reactor system to respond safely to feedwater transients and should be confirmed by a Comission order.
The Comission finds that operation of Davis-Besse 1 should rot be re-sumed until the actions described in paragraphs (a) through (g) above, with the exception as noted in item (a), have been satisfactorily completed.
For the foregoirs reasons, the Comission has found that the public health, safety and interest require that this Order be effective imedi-ately.
III.
Copies of the following documents are available for inspection at the Comission's Public Document. Room at 1717 H Street, N.W., Washington, 1
D.C.
20555, and are being placed in the Comissien's local public document room in the Ida Rupp Public Library, 310 Madison Street, Port Clinton, Ohio 43452:
(1)
Office of Nuclear Reactor Regulation Status Report on Feedwater Transients in B&W Plants, April 25, 1979.
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7590-01
, (2)
Letters from Lowell E. Roe (TECO) to Barold Denton (NRR) dated April 27 and May 4, 1979.
IV.
Accordingly, pursuant to the Atomic Energy Act of 1954, as amended, and the Comission's Rules and Regulations in 10 CFR Parts 2 and 50, IT IS HEREBY ORDcM 'HIAT:
(1)
The licensees shall take the following actions with respect to Davis-Besse 1:
a (a)
Review all aspects of the safety grade auxiliary feedwater system to further upgrade components for added reliability and performance. Present modifications will include the addition of dynamic braking cn the auxiliary feedpump turbine speed changer and provision of means for control room veri-fication of the auxiliary feedwater flow to the steam generators.
'Ihis means of verification will be provided for one steam generator prior to startup from the present maintenance outage and for the other steu generator as soon as vendor-supplied equipnent is available (estimated date is June 1,1979).
In addition, the licensees will review and verify the adequacy of the auxiliary feedwater system capacity.
(b)
Revise operating procedures as necessary to eliminate the option of using the~ Integrated Control System as a backup means i
for controlling the auxiliary feedwater system.
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7590-01 (c)
Implement a hard-wired control-grade reactor trip that would be actuated cn loss of rain feedwater and/or turbine trip.
(d)
Cocplete analyses for potential small breaks and develop and i=plement operating instructions to define operator action.
(e)
All licensed reactor operators and senior reactor operators will have completed the Sree Mile Island Unit No. 2 simulator trainire at B&W.
(f)
Submit a reevaluation of the TECO analysis of the need for autocatic or administrative control of steam generator level setpoints during auxiliary feedwater system operation previously mN,itted by TECO letter dated December 22, 1978, in light of the tree Mile Island No. 2 incident.
(g)
Submit a review of the previous TECO evaluation of the September 24, 1977 event involving equipment proble s and depressurization of the prirary system at Davis-Besse 1 in light of the Three Mile Island Unit No. 2 incident.
(2) The licensees shall raintain Davis-Besse 1 in a shutdown condition until items (a) throtsh (g) in paragraph (1), except as noted in item (a), above are satisfactorily cocpleted. Satisfactory completion will regaire confi mation by the Director, Office of Nuclear Reactor Regulation, that the
7590-01
- actions specified have been taken, the specified analyses are acceptable, and the specified implementing procedures are appropriate.
(3)
'Ibe licensees shall as prmptly as practicable also accomplish the long-term modifications set forth in Section II of this order V.
Within twenty (20) days of the date of this Order, the licensees or a y n
person whose interest may be affected by this Order may request a hea 1
4 with respect to this Order.
Any such request shall not stay the immediate effectiveness of this Order.
'IEE NUC r REGUINIDRY CCNMISSION
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Dated at Washington, D.C.,
i this ldb day of May 1979.
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NUCLEAR REGULATORY Com!ISSION l@
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Docket No. (s) 50-346 g
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- - l, CERTIFICATE OF SERVICE
=s I hereby certify that I have this day served the foregoing document (s)
[!b upon each person designated on the official service list compiled by I/s!
the Office of the Secretary of the Commission in this proceeding in}[ accordance with the requirements of Section 2.712 of 10 CFR Part 2 - Ff:, Rules of Practice, of the Nuclear Regulatory Commission's Rules and ff" Regulations, g.. E b = I Dated at. Washington, .C. this =_ x [ day of d44.- 197 / [!fg I
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c F UNITED STATES OF AMERICA NUCLEAR REGULATORY COMMISSION In the Matter of ) ) E TOLEDO EDISON COMPANY, ET AL. ) Docket No.(s) 50-346 mi _ ) ~ (Davis-Besse Nuclear Power ) Station, Unit No. 1) ) ) SERVICE LIST Mr. Donald H. Hauser, Esq. Harold Kahn, Staff Scientists The Cleveland Electric Power Siting Commission Illuminating Company 361 East Broad Street P.O. Box 5000 Columbus, Ohio 43216 Cleveland, Ohio 44101 Director, Technical Assessment F{= Gerald Charnoff, Esq. Division [: ' Shaw, Pittman, Potts ar' Office of Radiation Programs (AW-459) [.: Trowbridge U.S. Environmental Protection Agency G 1800 M Street, N.W. Crystal Mall #2 Washington, D.C. 20036 Arlington, Virginia 20460 Leslie Henry, Esq. U.S. Environmental Protection Agency Fuller, Seney, Henry & Hodge Feceral Activities Branch 300 Madison Avenue Region V Office Toledo, Ohio 43604 ATTN: EIS COORDINATOR 230 S. Dearborn Street ~ Mr. Robert B. Borsum Chicago, Illinois 60604 = Babcock & Wilcox Nuclear Power Generation Division Ohio Department of Health 7735 Old Geogetown Road, Suite 420 ATTN: Director of Health Bethesda, Maryland 20014 450 East Town Street Columbus, Ohio 43216 President, Board of County Commissioners of Ottawa County Port Clinton, Ohio 43452 Attorney General Department of Attorney General 30 East Broad Street 'olumbus, Ohio 43215 L:.:.: C 1 1 .- - -,}}