ML20058M845

Application for Amend to License DPR-65,changing Section 3.9.3.2 to Require Spent Fuel Pool Bulk Temp Be Maintained Below 140 F at All Times

ML20058M845
Person / Time
Site:	Millstone
Issue date:	08/07/1990
From:	Mroczka E NORTHEAST NUCLEAR ENERGY CO., NORTHEAST UTILITIES
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
Shared Package
ML20058M849	List: B13577, Proposed Tech Specs Re Refueling Operations ML20058M845
References
B13577, NUDOCS 9008130088
Download: ML20058M845 (5)

Text

p ni; ' a SF.

hQ w

W s

,1 4

p

[

M

' oeneral Offices e Selden Street, Berhn, Connecticut '

[

l N'UA*55I'EN P.O. BOX 270 t

.m.wac.u""

HARTFORD, CONNECTICUT 06141-027o :

k k

J CI,CE.Z,%",

(2o3) 665-5000.

' August 7, 1990-

-i Docket No. 50-336 l

B13577 l

1 g

Re:

10CFR50.90-l 1

i

..U.S. Nuclear Regulatory Commission Attention: ' Document Control Desk 4

- 3 y

. Washington, DC 20555

- l 4

i Gentlemen:

[

i A

Millstone Nuclear' Power Station, Unit No. 2

.,~

~ Proposed Change to Technical Specifications Refuelina Operations' Pursuant..to 10CFR50.90, Northeast huclear Energy Company - (NNECO): hereby_

proposes-to amend its Operating License No. DPR-65 by incorporating the-changes identified in Attachment l' into the Technical Specifications of (q'

. Millstone Unit No. 2.

+i

, Specifically, -the proposed Technical. Specification change' to Section-3.9.3.2 -

1 will require that the Spent Fuel Pool ~ (SFP) bulk temperature be' maintained-j

' below -140*F u at ' all times.. This proposed Limiting Condition for 0peration (LCO),would-~be applicable at all times as compared to the existing specifica-.

tion = only being applicable in Modes. 5' and for 504 hours0.00583 days <br />0.14 hours <br />8.333333e-4 weeks <br />1.91772e-4 months <br /> from subcriticality.

l following a-1/3 core offload. - Acti statements will - be : added ' to require

~

a immediate actions to restore the temperature below'.140*F and to record SFP temperature at least once per 4 hour4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br />sLif the Limiting Condition for:0peration

. is' not ' satisfied.

The surveillance requirement will also be revised to-l

. monitor the SFP temperature every.12. hours.

Also, the - Bases' Section 3/4.9.3 6,

will' be, modified to reflect these proposed changes to. Technical Specification

'3.9.3.2.

Qiscussiort

.j The existing Technical Specification.3/4.9.3.2, " Decay Time," states that two i

trains, of SFP cooling must be operable whenever the most-recent 1/3 core-offload has decayed less than' 504 hours0.00583 days <br />0.14 hours <br />8.333333e-4 weeks <br />1.91772e-4 months <br /> (21 days) from subcriticality.

It also'. states 'that 'this specification is not applicable if shutdown cooling 4

(SDC) is being used to cool the spent fuel pool.

The existing Technical Specification requires that both trains of SFP cooling bet operable because the highly conservative assumptions made in the design basis analysis for the latest spent fuel pool reracking showed that both trains were required to maintain SFP temperature below 140*F.

SDC was

-requ%d to cool the SFP.if one train of SFP cooling was inoperable because 90081300s8 900so7 v.

PDR ADOCK 05000336 d

r, pdc

' \\

j

e s

.w U.S. Nuclear Regulatory Commission B13577/Page 2 August 7, 1990 this conservative analysis'showed that the other train of SFP cooling was incapable of maintaining the pool below 140'F with the most recent 1/3 core offload decayed less than 504 hours0.00583 days <br />0.14 hours <br />8.333333e-4 weeks <br />1.91772e-4 months <br />.

Based on operational experience, the.cFP can, at most times, be maintained below 140'F using only one train of SFP cooling with the most recent 1/3 core decayed less than 504 hours0.00583 days <br />0.14 hours <br />8.333333e-4 weeks <br />1.91772e-4 months <br />...The, ability to maintain cooling with only one

-train-is a function of the number and residence time of the fuel assemblies in the pool and the temperature of the cooling water.

Because of the conserva-tive nature of the analysis, it overestimates heat loads, underestimates

cooling capabilities and does not

account for passive cooling mechanisms.

The proposed technical specification. requires that the SFP be maintained below 140'F in lieu of specifying train availability. Only one train of SFP cooling could be operating if conditions allow that train to maintain the temperature below 140'F.

To ensure that a single failure would not result in inadequate cooling to the SFP, the proposed Technical. Specification further requires -that the plant 'immediately take actions to restore the SFP to 140*F or less, if the temperature limit is exceeded.

Technical Specification 3/4.9.3.3, which requires that the plant remain in Mode 5 or 6 for at least 504 hours0.00583 days <br />0.14 hours <br />8.333333e-4 weeks <br />1.91772e-4 months <br /> from subcriticality after the most recent 1/3 core offload, remains unchanged, thus assuring that the SDC system can be made available to cool the SFP, if needed.

After 504 hours0.00583 days <br />0.14 hours <br />8.333333e-4 weeks <br />1.91772e-4 months <br />, even the conservative analysis shows that ore train of SFP cooling is able to maintain the pool at below 140*F.

The proposed modification to Technical Specification provides needed cpgra-tional flexibility since.it allows removal of one train of SFP coolir.g rrom service for maintenance of th-system or supporting systems, if the-other train can maintain pool terr.:

ature.

For ~ example, in a refueling putage, critical path time could be lost because one train of SFP could be out of service and Technical Specification 3.9.3.2 would not permit SDC to be iso-lated from the SFP.

In this scenario, the refueling cavity could not be lowered for reactor vessel work, even though the one train of SFF cooling in service could maintain SFP temperature below 140'F.

Both the existing and proposed Technical Specifications require that fuel movement be suspended and the pool purification damineralizers be isolated whenever the LC0 is not met.

The surveillance requirement to monitor the SFP temperature at least.once per '12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> whenever the peol is less thin or equal to 140*F provides assurance that this Technical Specifit:ation will be met.

Sianificant Hazards Consideration

- The proposed technical specification change has been reviewed against the criteria of 10CFR50.92 and it has been determined not to involve a significant hazards consideration.

Specifically, the proposed change does not:

1)

Involve a significant increase in the probability or consequences of any accident previously analyzed.

Y iQ Q >

b gy

.,0 1.

- e i,:

U.S. Nuclear Regulatory Commission y"

E B13577/Page 3 August.7, 1990 The' current Technical' Specification LC0 is-applicable in Modes 5_ andl 6 with:the most recent 1/3 core offload decayed less than 504 hours0.00583 days <br />0.14 hours <br />8.333333e-4 weeks <br />1.91772e-4 months <br /> from subcriticality.

There is no LCO on SFP cooling for times greater than 504 h'urs or'in other modes.

Since the proposed change ~ requires that the

~

o SFP temperature' be maintained below 140'F at all times, this LC0 is 'nore restrictive for times greater than 504. hours in Modes-5 and 6, or at any L

. times in; all other modes.

.The only -design basis accident considered for the SFP is f the fuel-handling accident.

The proposed changes do not affect -the consequences of a fuel-handling accident.

The other relevant event analyzed in the design basis: of the SFP cooling system is a complete loss of. SFP cooling (Final Safety. Analysis Report [FSAR] Section 9.5.3.3).

Two trains'of the SFP = cooling system. can maintain the SFP temperature below 131*F.

However, even assuming the initial pool temperature is at 140*F when the SFPiccoling is-lost,-the minimum time to boiling-(212*F) is-estimated to-be 8.5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br />.

This estimation assumes a normal 1/3 core off-load and does not-credit any passive heat ' losses.

With the emergency heat load (i.e., complete core off-load) on the SFP-under the same circumstances, the-minimum time to boiling is estiw.ted to be 3.5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br />.

Both times to

-boiling (8.5 and 3.5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br />) are sufficient for the operator to reinitiate:

the SFP cooling or line-up SDC.

It should be noted, Technical Specifica-tionL3'9.3.3 requires that the reactor be maintained in Modes 5 and 6 for at~1 east 504 hours0.00583 days <br />0.14 hours <br />8.333333e-4 weeks <br />1.91772e-4 months <br /> from subcriticality.

Therefore, the SDC system would remain available for at least 504 hours0.00583 days <br />0.14 hours <br />8.333333e-4 weeks <br />1.91772e-4 months <br /> for SFP cooling.

The' SFP liner, building structures, and racks have been qualified for a maximum water temperature under accident conditions of 212*F.

The SFP cooling system is qualified for a - design temperature of 200'F.

Therefore, even in the worst-case scenario, the proposed change would -

allow sufficient time to ensure the design limits of the SFP, spent'_ fuel racks, or' associated cooling systems are not exceeded.

-The existing one-hour action statement to isolate the SFP cleanup demin-l eralizers is still applicable and will protect the demineralizers from the : increased temperature.

Since there is no fuel movement permitted during this time period, the SFP area can be evacuated to ensure person-nel safety in case of SFP heat-up.

The proposed Technical Specification will mitigate the thermal conse-quenca:; of an SFP cocling system failure to the spent fuel racks by

-requiring immediate action, thereby reducing the duration of the event and' restoring the temperature in the SFP to less than or equal to 140'F.

Also, the proposed Technical Specification does not' significantly increase -the probability of a loss of cooling event to the spent fuel pool due to the continued availability of the SDC system within the 504 hours0.00583 days <br />0.14 hours <br />8.333333e-4 weeks <br />1.91772e-4 months <br /> from reactor shutdown (subcriticality).

f g

'[

}

e t

1' c

c.

U.S. Nuclear Regulatory Commission B13577/Page 4 August 7, 1990 L As-stated in' the' proposed Bases for the proposed Technical Specification,

~

limiting the SFP temperature to 140*F preserves-personnel-- comfort and safety and' prevents degradation of demineralizer resins. This Technical Specification has no impact on the design limits since the SFP structure, E

racks and all components of the SFP main cooling loop are designed to l,

withstand temperature of at-least 200*F.

The requirement to immediately initiate corrective action in all modes to restore pool temperature to 140'F, if the limit is exceeded, assures that corrective actions will be taken to maintain the SFP temperature below the design limits.

2)

Create the ' possibility of a new or different kind of accident.

The proposed. change does not-affect the way the plant is operated or, alter its Jresponse to any accident.

The current Technical Specification specifies no temperature limit for the SFP; whereas the proposed Technical Specification limits the t9mperature to 140*F.

_The pool temperature tmay exceed 140*F for: e

. ort period of time, while the corrective actions are being taken.

dowever, because of slow -heat-up rate of the'SFP cooling even in the' worst case, there would-be sufficient-time available to reinitiate pool cooling which assures that pool design limits will not be exceeded.

Therefore, the proposed change does not create the possibility of a new or different kind of accident.

Involve. a-significant reduction in margin of safety.

As stated above, 3) the current Technical Specification has no requirement that assures SFP

. cooling in ~ Modes 1 through 4, or greater-than 504 hours0.00583 days <br />0.14 hours <br />8.333333e-4 weeks <br />1.91772e-4 months <br /> after subcriti-cality in Modes 5 and 6.

The proposed change would specify that the SFP be maintained below 140'F at. all' times.

The pool temperature may exceed.

140*F for. a short period of time if a failure occurs in the SFP cooling system; however, the existing actions specified in the proposed change assure that temperature.is maintained below the design temperature of the pool', its components, fuel racks and the SFP cooling system.- There is no increase in the consequences of any accident and therefore no significant reduction in the margin of safety.

The Commission has also provided guidance concerning the application of' the

, standards in 10CFR50.92 by providing examples (51 F.R. 7751, March 6,1986).

The proposed changes described herein, in some respects, resemble example (vi). This example involves a change which either may result in some increase to the probability or consequences of a previously analyzed accident or. may.

reduce' in some way a safety margin, but where the results of the change are cle_arly within all acceptable criteria with respect to the system or component as: specified in the Standard Review Plan (e.g., a change resulting from the

-application of a small refinement to a previously used calculational model or design method).

As with this example, NNECO's proposed amendment involves no significant hazards consideration.

' The Millstone Unit No. 2 Nuclear Review Board has reviewed and approved the attached proposed revision and has concurred with the above determinations.

ww,-

s U.S. Nuclear Regulatory Commission B13577/Page15 August 7, 1990 NNECO. respectfully requests that-this proposed change be issued during the next refueling outage, currently planned to commence on September 15, 1990, but-priors to October-1,1990 to avoid a similar situation as noted above.

NNECO also requests this. license amendment be effective as of the date of its issuance, to be implemented within 30 days of issuance.

L In accordance with 10CFR50.91(b), we are providing the State of Connecticut with a copy of this proposed amandment application.

ry-truly yours, i.C.ifHEAST NUCLEAR ENERGY COMPANY a

-i m

E. K fir'oc~zKa~',f i

Seniof Vice Presi' dent cc: Mr. Kevin McCarthy J

Director, Radiation Control Unit Department of Environmental Protection

. Hartford, Connecticut 06116 a

T. T. Martin, Region I Administrator i

G. S. Vissing, NRC Project Manager, Millstone Unit No. 2 P. Habighorst,- Resident inspector, Millstone Unit No. 2 W. J. Raymond, Senior Resident Inspector, Millstone. Unit Nos. 1, 2, and 3 STATE OF CONNECTICUT)

) ss. Berlin COUNTY OF HARTFORD )

Then personally appeared before.me, E. J. Mroczka, who being duly -sworn, did

.i state:that he is. Senior Vice President of Northeast Nuclear Energy Company, a Licensee-herein, that he is = authorized - to execute and file the foregoing

.l information in the name and on behalf of the Licensee herein, and that the 1

statements contained in said information are true and correct to' the best of t

his knowledge and belief.

IhnssN 0

W 4totarf Pu c

MyComm!nb apresMarch31,1093 c:

I