ML20059F154
| ML20059F154 | |
| Person / Time | |
|---|---|
| Site: | Millstone  |
| Issue date: | 10/27/1993 |
| From: | Calvo J Office of Nuclear Reactor Regulation |
| To: | Opeka J CONNECTICUT YANKEE ATOMIC POWER CO., NORTHEAST NUCLEAR ENERGY CO. |
| References | |
| NUDOCS 9311040154 | |
| Download: ML20059F154 (5) | |
Text
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k UNITED STATES j'. W j
NUCLEAR REGULATORY COMMISSION t
WASHINGTON. O C. 20555 0001
- g October 27, 1993 Docket No. 50-423 N0ED No. 93-6-024 Mr. John F. Opeka
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Executive Vice President, Nuclear Connecticut Yankee Atomic Power Company Northeast Nuclear Energy Company Post Office Box 270 Hartford, Connecticut 06141-0270
Dear Mr. Opeka:
SUBJECT:
NOTICE OF ENFORCEMENT DISCRETION RELATED TO THE SUPPLEMENTARY LEAK COLLECTION AND RELEASE SYSTEM, AND AUXILIARY BUILDING FILTER SYSTEM LIMITING CONDITIONS OF OPERATION (TAC M87216)
This letter confirms that on October 25, 1993, the Nuclear Regulatory Commission (NRC) granted orally Northeast Nuclear Energy Company's (NNEC0's)'
request for enforcement discretion regarding Technical Specifications-(TS) applicable to the supplementary leak collection and release system (SLCRS) and the auxiliary building filter system (ABFS) operability requirements for the Millstone Nuclear Power Station, Unit 3.
On October 22, 1993, NNECO representatives requested the NRC to exercise its discretion nct to enforce compliance with Millstone 3 Technical Specification Limiting Condition of Operation 3.6.6.1 and 3.7.9.
Enforcement Discretion is necessary to allow Millstone Unit 3 to proceed to Mode 2_following'the current j
refueling outage to avoid a delay in plant start-up.
Permitting the plant to enter Modes 4, 3, and 2 includes establishing normal operating temperature and pressure and enables NNEC0 to commence surveillance and low power physics tests required upon completion of a refueling outage.
i During testing in September 1993, near the end of a refueling outage, NNECO determined that SLCRS could not meet its TS requirements for operability.
SLCRS and the auxiliary building ventilation system (ABVS), which includes the ABFS, are required to work in unison to allow SLCRS to draw down to 0.25 inches of vacuum on the secondary containment boundary within 1 minute following a design basis accident. Timing delays in the ABVS fan circuitry caused actual drawdown times in the secondary containment in excess of 60 seconds in certain system alignments. NNEC0 undertook extensive investigations and tests to chara.terize the SLCRS and ABVS systems. Three single failure vulnerabilities were identified and subsequently corrected by modifications. Adjustments in control circuitry timing, and subsequent tests j
have not shown that TS required drawdown times can be achieved. NNEC0, by letter dated October 22, 1993, proposed a revision to the TS to extend the required drawdown time to 150 seconds, and also requested enforcement-discretion while the proposed TS change is being processed.
In a meeting on October 25, 1993, at NRC headquarters in Rockville,'MD, NNEC0 presented the staff with results of its investigations and supported its proposed TS change.
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e Mr. John F. Opeka October 27, 1993 As justification for the requested enforcement discretion, NNEC0 provided the following rationale:
Drawdown of the Millstone Unit No. 3 secondary containment boundary to a.
i negative pressure of 0.25 inches water gauge is required by Technical Specifications to occur within 60 seconds of receiving a safety i
injection signal (this time includes the diesel generator. start and load _
1 time of approximately 10 seconds).
For a design basis loss of coolant accident (LOCA), credit is taken for SLCRS and ABFS performance. One hundred percent of core noble gases and fifty percent of core iodines are assumed to be instantaneously released to the containment at the start of the accident. Most of the activity which leaks into the secondary containment boundary is drawn through the ventilttion, filtered and reduced by a factor of 20 prior to release. The filters provide no reduction in noble gas activity. Hence, this discussiog
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focuses on the effects on iodine thyroid dose consequences.
An assessment of the dose consequences for such an event has concluded that i
the operation of Millstone Unit No. 3 from Modes 4 through 2 will not produce iodine ~ curies in sufficient quantity to excee'J the original filtered dose at 100% power. This assessment' assumed that SLCRS and ABFS were unavailable; therefore, the release from the secondary containment boundary was unfiltered.
Millstone Unit No. 3 has been shutdown for over 80 days for refueling.
Virtually all. iodine in the core has decayed away.
Only a small fraction (0.001) of the core iodines present at the end of Cycle 4 operation remain.
During Modes 3 and 4, no additional iodine is produced because the reactor remains subcritical.
Since the remaining inventory is significantly less than the 100% power equilibrium inventory, any release during Modes 3 or 4 even without filtration would be bounded by the 100% design basis LOCA assumptions.
The iodine produced in the core from operating Millstone Unit No. 3 in Mode 2 (i.e., 5% power or 1/20th of normal full power) is dependent upon power and time. Operating in Mode 2 for I week will result in core DEQ I-131 to be far below 1/20th of the respective curies of DEQ I-131 at full power based on the fact that equilibrium at this power will not be achieved for approximately 5 half-lives of the longest lived iodine, I-131 of approximately 8 days.
Thus, operating in Mode 2 for 1 week will produce resulting iodines (SIC) dose consequences for the postulated
- l event below what has already been analyzed and accepted. The rcsulting dose consequences for an accident during this operation (Mode 2 for 1-week) are bounded by the original design basis analysis.
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From analysis of the availabTe curies that could be assumed to be released following a design basis accident LOCA by operating Millstone Unit No. 3_through Modes 2, 3, and 4, it is apparent that the resulting dose consequences would be less than those calculated for 100% design -
i basis accident LOCA assumptions. Additional insights into the safety significance of this request was provided in the main body of this letter.
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Mr. John F. Opeka October 27, 1993 The auxiliary building ventilation system (ABVS) will be capable of 1
supporting the operation of the charging system and the reactor plant component cooling water system.
Therefore, Millstone Unit No. 3 can be operated in Modes 3 and 4 indefinitely before reaching' Mode 2, and upon Mode 2 operation can q
remain there for 1 week. This operation is acceptable for one time only following the current (Cycle 4) refueling outage.
Based upon our review of your justifications identified above, and the remaining supporting material provided in your submittal relative.to the justification for this Notice of Enforcement Discretion the staff has concluded that this course of action involves minimum safety impact, and we are satisfied that the exercise of enforcement discretion is warranted from a public health and safety perspective. Therefore, fi; is our intention to exercise discretion not to enforce compliance with Technical Specification Limiting Conditions of Operation 3.6.6.1 and 3.7.9.
Enforcement discretion is granted to allow Millstone Unit No. 3 to proceed up to Mode 2 without having to first demonstrate operability of the SLCRS and ABFS. The maximum time that the plant is allowed to remain in Mode 2 is 7 days before the SLCRS and ABFS must be demonstrated operable. At that time, the plant must proceed to Mode 3 and remain there until the LCOs are met. Although this exercise of enforcement discretion provides time for the staff to consider the proposed revision to TS, we will. consider enforcement action, as appropriate, for the-circumstances that led to the need for this exercise of enforcement-discretion.
Sincerely, Original signed by:
Jose A. Calvo, Assistant Dire-tor for Region I Reactors Division of Reactor Projects - I/II Office of Nuclear Reactor Regulation cc:
See next page DISTRIBUTION:
Docket file JStolz OPA NRC & Local PDRs VRooney OC/LFDCB PDI-4 Memo SNorris JLieberman, OE TMurley OGC TA, DRPE FMiraglia DHagan LDoerflein, RI JPartlow GHill (2)
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NAME SNorris VRooney:bp JStolz LCunningham' RCooper JCalvo DATE 10/26/93 10/27/93' 10/27/93 10/27/93 ft/27/93
/o/ 27/93 0FFICIAL RECORD COPY Document Name: G:\\R00NEY\\87216.END
Mr.1 John F. Opeka October 27, 1993 The auxiliary building ventilation system (ABVS) will be capable 'of supporting the operation of the charging system and the reactor plant component cooling water system.
Therefore, Millstone Unit No. 3 can be operated in Modes-3 and 4 indefinitely before reaching Mode 2, and upon Mode 2 operation can remain there for 1 week.
This operation is acceptable for one time only following the current (Cycle 4) refueling outage.
Based upon our review of your justifications identified above, and the remaining supporting material provided in your submittal relative to the justification for this-Notice of Enforcement Discretion the staff has concluded that this course of action involves minimum safety impact, and we are satisfied that the exercise of enforcement discretion is warranted from a public health and safety perspective.
Therefore, it is our intention toi exercise discretion not to enforce compliance with Technical Specification Limiting Conditions of Operation 3.6.6.1 and 3.7.9.
Enforcement discretion is granted to allow Millstone Unit No. 3 to proceed up to Mode 2 without havings to first demonstrate operability of the SLCRS and ABFS.
The maximum time that the plant is allowed to remain in Mode 2 is 7 days before the SLCRS and ABFS must be demonstrated operable. At that time, the plant must proceed to Mode 3 and remain there until the LCOs are met. Although this exercise of enforcement discretion provides time for the staff to consider the proposed..
revision to TS, we will consider enforcement action,' as appropriate, for the circumstances that led to the need for this exercise of enforcement discretion.
Sincerely, m!
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Jose A. Calvo, Assistant Director for Region I Reactors Division of Reactor Projects - I/II Office of Nuclear Reactor Regulation cc:
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4 Mr. John F.-0peka Millstone Nuclear Power Station Northeast Nuclear Energy Company Unit 3 1
cc:
1 Gerald Garfield, Esquire R. M. Kacich, Director Day, Berry and Howard Nuclear Licensing Counselors at Law Northeast Utilities Service Company City Place Dost Office Box 270 Hartford, Connecticut 06103-3499 Hartford, Connecticut 06141-0270 W. D. Romberg, Vice President J. P. Stetz, Vice President Nuclear Operations Services Haddam Neck Plant Northeast Utilities Service Company Connecticut Yankee Atomic Power Company.
Post Office Box 270 362 Injun Hollow Road Hartford, Connecticut 06141-0270 East Hampton, Connecticut 06424-3099 Kevin T. A. McCarthy, Director Regional Administrator i
Monitoring and Radiation Division Region I Department of Environmental Protection U.S. Nuclear Regulatory Commission 79 Elm Street 475 Allendale Road Post Office Box 5066 King of Prussia, Pennsylvania 19406 Hartford, Connecticut 06102-5066 Allan Johanson, Assistant Director First Selectmen Office of Policy and Management Town of Waterford Policy Development and Planning Division Hall of Records 80 Washington Street 200 Boston Post Road Hartford, Connecticut 06106 Waterford, Connecticut.06385 S. E. Scace, Vice President P. D. Swetland, Resident Inspector Millstone Nuclear Power Station Millstone Nuclear Power Station Northeast Nuclear Energy Company c/o U.S. Nuclear Regulatory Commission Post Office Box 128 Post Office Box.513 Waterford, Connecticut 06385 Niantic, Connecticut 06357 F. R. Dacimn, Nuclear Unit Director M. R. Scully, Executive Director Millstone Unit No. 3 Connecticut Municipal Electric Northeast Nuclear Energy Company Energy Cooperative Post Office Box 128 30 Stott Avenue Waterford, Connecticut 06385 Norwich, Connecticut 06360 Burlington Electric Department David W. Graham c/o Robert E. Fletcher, Esq.
Fuel Supply Planning Manager 271 South Union Street Massachusetts Municipal Wholesale Burlington, Vermont 05402 Electric Company-Post Office Box 426 Nicholas S. Reynolds Ludlow, Massachusetts 01056 Winston & Strawn 1400 L Street, NW J. M. Solymossy, Director' Washington, DC 20005-3502 Nuclear Quality and Assessment Services Northeast Utilities Service Company Post Office Box 270
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Hartford, Connecticut.06141-0270 o
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