ML20091K761
| ML20091K761 | |
| Person / Time | |
|---|---|
| Site: | 05000000, FitzPatrick |
| Issue date: | 08/29/1983 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML17139C189 | List:
|
| References | |
| FOIA-84-105 NUDOCS 8406070194 | |
| Download: ML20091K761 (13) | |
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-s w ENCLOSURE A f, ${$
SA FETY EVAL UA TION JAMES REPORT A.
FIT 2PA TRICK N-1 LOOP NUCLEAR OPERATION POWER PL ANT (J A F) 1.0 The current JAF Te hnical operation beyond 24 Spec ific a t ions c
not be returned hours if an idl not allow do to e
r duc d service.
recirculatio plant e
e power The n
with a ava il ab il ity/outagsingle to p ability to loop can operate e
" maintena e planning standis highty desi at nce or rable c
inocerable.
omponent u point from in the navailability r event that endered one loop
?y letter dated Dec sw York (PASNY)ember 29, 1982 chn ical (the lic Pow er Authority of ensee)
Spec ifica t io requ
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quested changes n for Single Loo changes the State ested of i
to the
'ed would p Operation power perm't JAF with one to of JAF.
While recirculation l operate The a t up a
single loopnalyses indicateoop out to'50% of of s in the that it may be ervice for Lience (refer range higher sa fe unl im ited o H. Dentone e let.ter from L n 50% of ratedto operate BWR enc tha s
NRC) a t ' Browns Ferry U. M. M il l s, TVA power Olov e the and dated March power at 50% ratedoscillations.
has caused co nit 1
'en 17, Howev power er at becau ncern e
several pla ts, single loop se n
including Br t
owns B4060{0194840319
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Ferry. Plant Unit is has shown acceptable flow and power c h a r a c t e r is tic s, we wiLL permit PASNY to operate at power levels up to 50% of rated with one loop out of service.
If requested, we'wilL recons'ider operation at a higher power level for JAF with one recirculation loop out of service after staff concerns stemming from Browns Ferry - Unit 1 single loop operation are satisfied.
2-EVALUATION 2.1 Accidents (Other than Loss of Coolant Accident (LOCA) and Trrnsients Affected by One Recirculation Looo out of Service
'2.1.
1 One Pumo Seizure Accident The Licensee states that the one pump seizure accident is a relatively mild event during two recirculation pump operation.
1 Similar analyses were performed to determine the impact this accident would have on one recirculation pump operation.
These' analyses were. performed using NRC approved models for a l
Large core BWR/4 plant.
The analyses were conducted from steady-state operation at-the following' initial conditions, with l
the added condition of one_ inactive recirculation loop.
Two
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sets of. initial conditions were assumed:
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l a.
Thermal Pcwer = 75% and core flow = 58%. of rated i
b.-
Thermal Power = 82% and core flow = 56% of rated l
o Os These conditions were chosen because they represent reasonable s
upper limits of single-loop operation within existing Maximum Av e r a ge P L,a na r L i ne a r H e a t Generation Rate (MAPLHGR) and Minimum Critical Power Ratio (MCPR) Linits at the same maximum pump speed.
Pump seizure was simulated by setting the single ope ra t ing Pum'p speed to ze ro -instantanedus t y.
The anticipated sequence of events folLowing a recirculation pump-seizure which occurs during plant operation with the alternate recirculation loop out of service is as folLows:
'n the loop in which a.
The recirculation' Loop flow i the pump seizure occurs drops instantaneousty to zero.
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b.
Core yoiding increases whi.ch.results in.a n'egative reacti'vity insertion and sharp decrease in neutron flux.
c.
Heat flux drops more slowly because of the fuel time constant.
d.
Neuton fluxi heat fluxi reactor water leveli steam flows and feedwater flow alL exhibit transient behavior.
However, it is not anticipated that the increase in water level wilL cause a turbine trip and result in scram.
The. transient wilL terminate at a condition of natural circulation and reactor operation wilL continue.
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'There will'also be a small decrease in system pressure.
The licensee concludes that the f1CPR for the pump seizure l
ac c ident for the large core BWR/4 plant was determined to be greater than the fuel cladding integrity safety limit; thereforer no fuel failures were postulated to occur as a result of this analyzed event.
These results are applicable to JAF.
2.1. 2 Abnormal Transients 2.1.2.'1 a.
Idle Loop Startup The idle loop startup transient was analyzedi 'in the JAF FSARr with an initial power of 65%., The Licensee is to operate at no greater than 50% power with gne loop out of service.
Additionally, the Technical Specifications are being modified to require thate during single loop operationi the suction valve in the idle loop be shut and electrically disconnected.
These measures are being taken to preclude startup of an idle Loop.
b.-
FLou Increase-For single-loop operations the rated condition steady-state MCPR Limit is increased by 0.01 to account for increased uncertainties
-in the core total flow-and Traversing In-core Probe (TIP)-
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i-2** readings..The MCPR wilL vary depending on flow conditions.
This leads to the possibility of a large inadvertent flow l
increase which could cause the MCPR to decrease below the Safety Limit for a low initial MCPT. at reduced flow conditions.
Thereferer the required MCPR must be increased at reduced core.ft'ow by a flow factor K The K factors are f.
f derived assuming both recirculation loop pumps. increase speed to the maximum permitted by the M-G set scoop tube position set screws.
This condition maximizes the power increase and hence maximum.A MCPR for transients initiated from less than rated conditions.
When operating on one loop the flow and power increase wilL be less than associated with two pumps increasing speed, therefore, the K factors derived from the two pump f
s assumption are conservative for single Loop operation.
c.
Rod Withdrawal Error The rod withdrawal error at rated power is given in the FSAR for the initial core and in cycle dependent reload supplemental submittals.
These analyses are performed to demonstrate that, even if the operator ignores atL instrument indications and the alarm which could occur during the course of the transient, the rod block system wilL stop rod withdrawal at a minimum critical power ratio which is higher than the fuel cladding integrity safety limits.
Correction of the rod block equation and lower initial power for single-loop operation assures that the MCPR safety Limit is not violated.
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4-L L0ne pump operation results in backflow through jet pumps while flo,w.is being supplied to the lower plenum from the 1
active jet pumps.
Because of'this backflow throtqh the inactive jet pumps the present cod-block equation and APRM settings must be modified.
The licensee has modified i
the two pump rod block equation and APRM settings that exists in the Technical Specification for one pump operation 9
and the staff has found them acceptable.
The staff finds that one loop transients and accidents other than LOCA, which is discussed below, are bounded by the two loop operation analysis and are therefore acceptable.
s 2.2 Loss of Coolant Accident (LOCA)
The Licensee _has contracted General Electric Co.-(GE) to per-form single loop operation analysis for JAF LOCA.
The Licensee states ~that evaluation of these calculations (that are performed according to the procedure outlined in NED0-20556-2, Rev. 1) indicates that a multiplier of 0.84 -(8x8Ri-P8x8R) and 0.85 (8x8 Fuel) (Ref:
-NED0 24281 August 1980, Errata and Addenda Sheet No. 1r December 1980) -should be applied to the MAPLHGR' Limits for single loop operation of JAF.
We find the use of these MAPLHGR multipliers to be acceptable.
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s 3.
THERMAL HYDRAULICS s
The Licensee has confirmed that analysis uncertainties are independept of whether flow is provided by two Loops or single loop.
The onty exceptions to this are core total flow and TIP reading.
The effect of these uncertainties is an increase in the MCPR by.01, which is more than offset by the K factor f
required at low' flows.
The steady state operating MCPR with single-loop operation wilL be conservatively established by multialying the K factor to the rated flow MCPR Limit.
f 4.
. STABILITY ANALYSIS-The Licensee wilL be required to operate in master manual to reduce the effects of instabilities due to controller feedback.
The staff-has accepted previous stability analyses results as evidence that the core can be operated safely while our generic evaluation of BWR stability characteristics and analysis methods k-continues.
Our acceptance is based on the fotLowing:
i The Licensee stated that oscillatory problems have not i
i been experienced at the JAF Station during single loop operation.
The Licensee wilL monitor APRM flux noise and core plate delta P noise at about 40 percent of power for a period 4
j of.1/2 hour to 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> to establish a baseline noise level.
This baseline-noise level (peak to peak oscillation) wilL be increased by 50 percent to establish a maxi, mum
-w-allowable level.
The noise will be measured once 2N-per shift and the recirculation pump speed will be reduced if the flax noise exceeds the maximum allow-
.able level.
The maximum allowable power level during SLO will be 50 percent.
l We conclude that with appropriate limitations to recognize and avoid operating instabilities, the reactor can be operated safely in the single loop mode.
Our evaluation of the flow / power oscillations evidenced in Browns Ferry will con-tinue and any pertinent conclusions resulting from this study will be applied to JAF.
5.
SUMMARY
ON SINGLE LOOP OPERATION 1.
Steady State Thermal Power Level will not i
exceed 50%.
Operating at 50% power with appropriate TS changes was approved on a cycle basis for Pilgrim 1, Cooper Nuclear Station, Monicell'o Nuclear Generating Station and Brunswick Units 1 &2 (Safety Evaluation Reports (SER) dated December 15, 1981, December 10, 1981, September 10, 1982 and December 21, 1982 respectively).
Authorization for single loop operation for ex-tended periods was also given to Dresden Unit 2 and 3, Quad C ities Units 1 and 2, Peach Bottom Units 2 and 3 and Duane Arnold
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(SER July 9, 1981, SER November 19, 1981).
It was concluded that for operation at 50%, power transient and accident bounds would not be exceeded for these plants.
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2.
Minimum Critical Power Ratio (MCPR) Safety Limit will be Increased by 0.01 to 1.08 The MCPR Safety Limit will be increased by 0.01 to account for increased uncertainties in core flow and Traversing Incore Probe (TIP) readings.
The licensee has reported that this in-crease in the MCPR Safety Limit was addressed in GE reports specifically for JAF for one loop operation.
On the basis of previous staff reviews for Pilgrim 1, Cooper, Duane Arnold, Monticello and Peach Bottom and our review of plant comparisons we find this analysis acceptable for JAF.
3.
Minimum Critical Power Ratio (MCPR) Limiting Condition for Operation ^(LCO) will be Increased by 0.01 The staff requires that the operating limit MCPR be ir, creased by 0.01 and multiplied by the appropriate two loop Kf factors that are in the JAF TS.
This will preclude an inadvertent flow i
increase from causing the.MCPR to drop below the safety limit MCPR.
This was also approved by the staff for Peach Bottom 2 and.3.
4.
The Maximum Average Planer Linear Heat Generation Rate (MAPLHGR) Limits will be Reduced by Aporopriate Multipliers The licensee proposed reducing the TS MAPLHGR by 0.84 (8x8R, fx8x8R Fuel ), 0.85 (8x8 Fuel) for Single Loop Operation.
These reductions I-
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'N were based on analyses by General Electric (GE) in reports NEDE 24011-P-A-1 and NEDO 24281.
The Peach Bottom units were al'lo'wed to operate with their MAPLHGR values reduced by factors of 0.71, 0.83, and 0.81 for an unlimited period of time.
5.
The APRM Scram and Rod Block Setocints wilL be Reduced The licensee proposed to modify the two loop APRM Scram, Rod Block ~and Rod Block Monitor (RBM) setpoints to account for.back flow through half the jet pumps.
The changes were based on plant specific analyses by GE.
These setpoint equations wilL be changed in the JAF TS.
The above changes are similar to the Peach Bottom TS changes and are acceptable to the staff.
J.
6.
The Suction Valve in the Idle Looo is Closed and Electrically Isolated The Licensee wilL close the recirculation pump suction valve and remove power from the valve.
In the event of a loss of coolant accident this would preclude partial loss of LPCI flow through the recirculation loop degrading the intended LPCI performance.
The removal of power also hetps to preclude a startup of an idle loop transient.
N 7.
The Recirculation Contro'l will be in Manual Con + ol The staff require, that the licensee operate the recirculation system in the manual mode to eliminate the need for control system analyses and to reduce the effects of potential flow instabilities.
This was also required of Peach Bottom.
8.
Surveillance Requirements i
The staff requires that the licensee perform daily surveillance on the jet pumps to ensure that the pressure drop for one jet pump in a loop does not vary from the mean of all jet pumps in that loop by more than 5%.
9.
Provisions to Allow Operation with One Recirculation Looo Out of Service 1.
The steady-state thermal power level will not exceed 50% of rated 2.
The Minimum Critical Power Ratio (MCPR) Safety Limit will be increased by.01 to 1.08 (T.S. 3.1 B) 3.
The MCPR Limiting Condition for Operation (LCO) wiLL be increased by 0.01 4.
The Maximum Average Flanar Linear Heat Generation Rate (MAPLHCR) Limits wiLL be reduced.
Fuel Type Reduction Factor 8x8 0.85 8x8R 0.84 P8x8R 0.84
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5..
The APRM Scram and Rod Block Setpoints and the RBM Setpoints, shall be reduced to read as follows:
T.S. 2.1.C(1)
S$ (.66W + 54% -0.66 AW) i T. S. 2.1.C C1 )*
SS (.66W + 54% -0.66 AW)TPF(#FP4 /MTPF(MFLPD)
T.S 2.1. A.1. 0 SI (.66W + 42%
.66 AW)
T.S. 2.1. A.1. D* SI (. 6 5 W + 4 2 %
.66 AW)TPFCFRP)/MTPF(MFLPD}
APRM Upscale (.66W + 42%
-0.66 aW)
RBM Upscale (.66W + K -0.66. au)- (K* Int e rc ept values of 39%, 40%, 41%, 42%, 43% ard 44% can be used with Appropriate MCPR Limits From Section 3.1.8)
The suction valve in the idle loop is closed and electrically isolated until the idle loop is being prepared for return t o.
service.
7.
The licensee will monitor APRM flux noise and core plate delta P noise at about 40 percent of power for a period of 1/2 hour to 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> to establish a baseline noise level.
This baseline noise level (peak to peak oscillation) will be increased by 50 percent to establish a maximum allowable level.
The noises will be measured once per shift and the recirculation pump speed will be reduced i f the flux noise
. exceeds the maximum allowable level.
Sased upon the absve. evaluation and,a his.to.ry of suscessf.u.L operation'of othe'r BWRs of;the same. type a s. J A F 's we constude..,
that single-loo.p.oper'ati,on.of JAF up.to a power,L..evel.
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of 50% and in accordance with the proposed TSsr will not exceed the accident and transient bounds previously found acceptable by the NRC staff and is therefore acceptable.
We have concluded, based on the considerations discussed above, that:
(1 ) because the amendment does not involve a significant increase in the probability or consequences of accidents previously considered or create a possibility of an accident of a type different from any evaluated previously, and does not involve a significant decrease in a safety margin, the amendment does not involve a significant-hazards consideration,'(2) there is reasonable
-assurance that.the health and safety of the public will not be endangered by operation in the proposed manner, and (3) such activities wilL be conducted in compliance with the Commission's regulations and the issuance of this amendment wiLL not be inimical to the common defense and security or to the health and safety of the public.
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