ML20081K883

Safety Evaluation Supporting Amend 143 to License DPR-28

ML20081K883
Person / Time
Site:	Vermont Yankee File:NorthStar Vermont Yankee icon.png
Issue date:	03/23/1995
From:	Office of Nuclear Reactor Regulation
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ML20081K866	List: ML20081K865 ML20081K883
References
NUDOCS 9503290329
Download: ML20081K883 (5)

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SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO AMENOMENT NO.143 TO FACILITY OPERATING LICENSE NO. DPR-28

, VERMONT YANKEE NUCLEAR POWER CORPORATION j

VERMONT YANKEE NUCLEAR POWER STATION

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DOCKET NO. 50-271 l

1.0 INTRODUCTION

i By letter dated December 8,1994, as supplemented by letter dated February 16, 1995, the Vermont Yankee Nuclear Power Corporation (the licensee) submitted a

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request for changes to the Vermont Yankee Nuclear Power Station Technical Specifications (TSs), Sections 3.7.B and 4.7.B.

The requested changes would I

(1) clarify the alternate power source requirements for the standby gas i

treatment system (SGTS) during the performance of fuel handling activities; j

(2) clarify the time requirements related. to laboratory carbon sample analysis j

of the SGTS; and (3) clarify the definition of SGTS system operation for i

determining the frequency of specified tests. By the letter dated February 16, 1995, the licensee revised the proposed changes to TS Section 3.7.B.I.b and the corresponding Bases.section to clarify that the associated i

emergency diesel generator (EDG) or Vernon tie provide alternate electrical i

power sources to the normal offsite auxiliary electrical power source required for SGTS operability. The February 16, 1995, letter provided clarifying l

information that did not change the initial proposed no significant' hazards consideration determination.

2.0 EVALUATION 2.1 Standby Gas Treatment Durina Refuelina Operations The licensee proposed to change Vermont Yankee TS Sections 3.7.B.1 and 3.7 D.3.

TS Section 3.7.B.1 currently reads as follows:

"Except as specified in-Specification 3.7.B.3 below, both circuits of the standby gas treatment

. system and the diesel generators required for operation of such circuits shall i

be operable at all times when secondary containment integrity is required."

The licensee proposed to change TS Section 3.7.B.1 into two Sections 3.7.B.I.a and 3.7.B.1.b to read as follows:

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i 3.7.B.1.a Except as specified in Specification 3.7.B.3.a below, whenever the reactor is in Run Mode or Startup Mode, both circuits of the Standby Gas Treatment System shall be operable at all times when secondary containment integrity is required.

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3.7.8.1.b Except as specified in Specification 3.7.8.3.b below, whenever the reactor is in Refuel Mode, both circuits of the Standby Gas Treatment System and an alternate electrical power source, consisting of the associated Emergency Diesel Generator or Vernon tie, for each i

standby gas treatment circuit shall be operable at~ all times when secondary containment integrity is required.

l; TS Section 3.7.B.3 currently reads as follows:

"From and after the date that l

one circuit of the standby gas treatment system is made or found to be inoperable for any reason, reactor operation is permissible only during the succeeding seven days unless such circuit is sooner made operable,, provided that during such seven days all active components of the other standby gas l

treatment circuit shall be operable." The licensee proposed to change the TS Section 3.7.B.3 into Sections 3.7.B.3.a and 3.7.B.3.b to read as follows:

l 3.7.B.3.a From'and after the date that one circuit of the Standby Gas Treatment System is made or i

found to be inoperable for any reason, reactor operation is permissible only during the i

succeeding seven days unless such circuit is i

sooner made operable, provided that during i

such seven days all active components of the other standby gas treatment circuit shall be operable.

l 3.7.B.3.b From and after the date that one circuit of the Standby Gas Treatment System is made or found to be inoperable for any reason, operations requiring secondary containment are permissible only during the succeeding seven days unless such circuit is sooner made operable, provided that during such seven days all active components, including the i

associated Emergency Diesel Generator of the j

other standby gas treatment circuit shall be i

operable.

i The licensee modified the Bases section (TS Section 3.7.C) by adding the l

followir.g:

I When the reactor is in cold shutdown or refueling the drywell may be open and the Reactor Building becomes the only containment system.

During cold shutdown the probability and consequences of a DBA LOCA l

are substantially reduced due to the pressure and temperature 1

limitations in this mode. However, for otMr situations under which significant radioactive release can be postulated, such as during j

operations with a potential for draining the reactor vessel, during i

core alterations, or during movement of irradiated fuel in the l

secondary containment, operability of standby gas treatment is required. An alternate electrical power source for the purposes of i

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Specification 3.7.B.1.b shall consist of either an emergency diesel i

generator (EDG) or the Vernon Hydro tie line. Maintaining availability of i

the Vernon Hydro tie line as an alternative to one of the EDGs in this condition provides assurance that standby gas treatment can, if required, be operated without placing undue constraints on EDG maintenance availability.

Inoperability of both circuits of the SGTS or both EDGs during refueling operations requires suspension of activities that

.t represent a pqtential for releasing radioactive material to the secondary l

containment, thus placing the plant in a condition that minimizes risk.

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The licensee stated that TS Section 3.7.8.1 as presently written imposes a requirement that both EDGs be available during refueling operations so that both circuits of the SGTS are operable. The licensee proposes to eliminate 4

reference in TS Section 3.7.8.1.a to the EDGs during power operation (a subject adequately addressed in TS Section 3.10) and to add a TS Section 3.7.B.I.b to address refueling operations. The licensee would revise the limiting conditions for operation LC0 in TS Section 3.7.B.3 to' include.

i requirements in the operating mode (TS Section 3.7.B.3.a) and would add 1

requirements applying to other operations requiring secondary containment (TS j

Section 3.7.B.3.b).

The proposed amendment specifies the requirements for i

electrical power availability for the SGTS system during all operations and l

gives operability requirements that are safe, reasonable, and consistent with i

license conditions at other BWR facilities.. The proposed amendment requires j

that an alternate power supply be available in the event that an emergency diesel generator is out of service during refueling operations (currently not l

a requirement). The licensee stated that keeping the Vernon tie line available as an alternate electrical power source that can be substituted for i

an out-of-service EDG during refueling will ensure that either train of SGTS can, if required, be operated without entering a LCO. The availability and j

reliability of this substitute alternate power source are comparable to those of the EDGs, and it can be quickly connected to either emergency bus from the t

control room by manual action.

l These TS changes do not alter the function of the SGTS or any TS setpoint.

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The changes do not affect any safety analysis in the final safety ar.alysis report (FSAR) or change the function of any equipment. The changes will allow the licensee to voluntarily remove an EDG from service without entering an LCO during refueling outage when containment integrity is required and will make the Vermont Yankee TS consistent with the license conditions of other i

BWR facilities. Accordingly, the NRC staff finds the proposed change l

acceptable.

2.2 Laboratory Carbon Samole Analysis

.l'I The licensee proposed to change TS Section 3.7.B.2.b to clarify the time requirements related to laboratory carbon sample analysis of the SGTS. TS l

Section 3.7.B.2.b currently reads as follows:

"The results of laboratory

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carbon sample analysis shall show ;t95% radioactive methyl iodide removal.

(130*C, 95% RH)"

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. The licensee proposed to change TS Section 3.7.B.2.b to read as follows:

The results of laboratory carbon sitmple analysis shall show ;t95%

radioactive methyl iodide ren; oval.

(130*C, 95% RH). Laboratory analysis results shall be verified acceptable within 31 days following sample removal or the applicable train of the Standby Gas Treatment System shall be considered in-operable and the requirements of Specification 3.7.B.3 shall apply.

The licensee stated that, since it typically takes several weeks to obtain completed results of laboratory analyses, it has become necessary for the licensee to remove the laboratory samples for analysis in advance of the anticipated end of the test interval. Determining the start and end of test intervals in relation to the time of removal of the sample and time of completion of laboratory analysis has required some judgment on the part of the licensee. The licensee also stated that c'etermining operability relative to test interval, sample removal, and completion of laboratory analysis requires clarification. To clarify the appropriate requirements, the licensee proposed to incorporate an explicit statement of the time following sample removal allowed for completion of the analysis and the determination of operability during this interval. The proposed statement is consistent with guidance provided by the NRC staff in Generic Letter 83-13. Therefore, the NRC staff finds the proposed change acceptable.

2.3 Torus Vent Mode The licensee proposed to change TS section 4.7.B.2.c to clarify the definition of system operation used to determine the surveillance test interval related to laboratory carbon sample analysis and halogenated hydrocarbon tests of the SGTS. TS 4.7.B.2.c currently reads, in part, as follows:

"In addition, the sample analysis of Specification 3.7.B.2.b and the halogenated hydrocarbon test shall be performed af ter every 720 hours0.00833 days <br />0.2 hours <br />0.00119 weeks <br />2.7396e-4 months <br /> of system operation."

The licensee proposed to change that portion of TS section 4.7.B.2.c to read as follows:

In addition, the sample analysis of Specification 3.7.B.2.b and the halogenated hydrocarbon test shall be performed after every 720 hours0.00833 days <br />0.2 hours <br />0.00119 weeks <br />2.7396e-4 months <br /> of normal system operation.

Additionally, the licensee added a related note to the Bases as follows:

Use of the SGTS, without the fan and the 9 kW heater in operation, as a vent path during torus venting does not impact subsequent adsorber capability because of the very low flows and because humidity control is maintained by the standby I kW heaters, therefore operation in this manner does not accrue as operating time.

6 The licensee stated that operation of the SGTS in the torus venting mode results in insignificant flow through the filters (<1% of rated design flow).

Additionally, the licensee noted that since the 1 kW heaters are operated in this mode, low humidity is maintained and adsorber degradation is prevented.

The licensee proposed to add the word " normal" to the specification such that system operation in the torus venting mode will not be included in determining the surveillance interval. The licensee asserts that there are no safety consequences to this clarification.

The proposed TS change does not alter the function of the SGTS or any TS setpoint. The change does not affect any safety analysis in the FSAR or change the function of any equipment. The laboratory carbon sample analysis and the halogenated hydrocarbon test will continue to be required after every 720 hours0.00833 days <br />0.2 hours <br />0.00119 weeks <br />2.7396e-4 months <br /> of system operation that has potential to degrade filter capability.

Therefore, the NRC staff finds this change acceptable.

3.0 STATE CONSULTATION

In accordance with the Comission's regulations, the Vermont State official was notified of the proposed issuance of the amendment. The State official had no coments.

4.0 ENVIRONMENTAL CONSIDERATION

i The amendment changes a requirement with respect t installation or use of a facility component located within the restricted area as defined in 10 CFR Part 20 and changes surveillance requirements. The NRC staff has determined that the amendment involves no significant increase in the amounts, and no significant change in the types, of any effluents that may be released offsite, and that there is no significant increase in individual or cumulative occupational radiation exposure. The Comission has previously issued a proposed finding that the amendment involves no significant hazards consideration, and there has been no public coment on such finding (60 FR 8759). Accordingly, the amendment meets the eligibility criteria for categorical exclusion set forth in 10 CFR 51.22(c)(9).

Pursuant to 10 CFR 51.22(b) no environmental impact statement or environmental assessment need be prepared in connection with the issuance of the amendment.

5.0 CONCLUSION

The Comission has concluded, based on the considerations discussed above, that:

(1) there is reasonable assurance that the health and safety of the public will not be endangered by operation in the proposed manner, (2) such activities will be conducted in compliance with the Comission's regulations, and (3) the issuance of the amendment will not be inimical to the comon defense and security or to the health and safety of the public.

Principal Contributors:

A. Pal D. Dorman Date: March 23, 1995 l

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