ML20106H119
| ML20106H119 | |
| Person / Time | |
|---|---|
| Site: | McGuire, Mcguire  |
| Issue date: | 02/08/1985 |
| From: | Tucker H DUKE POWER CO. |
| To: | Adensam E, Harold Denton Office of Nuclear Reactor Regulation |
| References | |
| RTR-NUREG-0737, RTR-NUREG-737 NUDOCS 8502150184 | |
| Download: ML20106H119 (12) | |
Text
s DUKE POWER GOMPAhT P.O. HOX 33180 CHARLOTTE,N.O.28242 HAL B. TUCKER ruternoxn J""l"_"'_"'
February 8, 1985
(*) *
- Mr. Harold R. Denton, Director Office of Nuclear Reactor Regulation U. S. Nuclear Regulatory Commission Washington, D. C. 20555 Attention:
Ms. E.
G.' Adensam, Chief Licensing Branch No. 4 Re: McGuire Nuclear Station Docket Nos. 50-369 and 50-370
Dear Mr. Denton:
Ms.' E. G. Adensam's letter of December 19, 1984 transmitted a request for additional.information regarding the McGuire Nuclear Station's Safety Parameter Display System.
The attached response addresses the specific concerns of the staff regarding the SPDS.
Very truly yours, hb.
/$
Hal B. Tucker RLG/mjf Attachment cc:
Dr. J. Nelson Grace, Regional Administrator U. S. Nuclear Regulatory Commission Region II 101 Marietta Street, NW, Suite 2900
-Atlanta, Georgia 30323 Mr. Darl Hood, Project Manager Division of Project Management Office of Nuclear Regulatory Commission
. Washington, D. C. 20555 NRC Resident-Inspector.
McGuire Nuclear Station L
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s DUKE POWER COMPANY MCGUIRE NUCLEAR STATION RESPONSE TO NRC REQUEST FOR ADDITIONAL INFORMATION -
MCGUIRE SAFETY PARAMETER DISPLAY SYSTEM (SPDS)
January 31, 1985 REQUEST:
The' licensee's submittal, H. B. Tucker (Duke) To H. R. Denton (NRC),
- March 9, 1984,. Attachment Section 4, does not provide evidence that Critical Safety Functions for SPDS, Section 4.1(f) of NUREG-0737, Supplement 1,
were considered in the selection of McGuire SPDS variables.
1.
Provide a listing of the variables proposed for the display on the McGuire SPDS that constitute sufficient information to allow 2 control room operators to assess the status of:
a.
reactivity control b.
reactor core cooling and heat-removal from the primary system o.
' reactor coolant system integrity d.-
radioactivity control e.
containment conditions
RESPONSE
' Section ~ 4.1.4 of H.
B.. Tucker's (Duke) To H.
R. Denton. (NBC),
' March 9, 1984 submittal contains six (6) ' Critical. Safety Funo-
~
.tions (CSF) which, for. Westinghouse plants, address the same
- functions referenced in section 4.1(f) of NUREG-0737, Supplement 1.-
The basis for the selection of these -six CSF's is contained in the document " Background Information for Westinghouse Owners
. Group Emergency Response Guidelines",.HP/LP-Rev. 1, dated Septem-ber-1,L1983, under the tab named " Status Trees".
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- MCOUIRE NUCLEAR STATION SPDS RESPONSES' January 31, 1985 Page 2 The results of the NRC's review of Rev.1 of these guidelines is contained in D. G. Eisenhut (NRC) letter dated December 27, 1985
- addressed to J. J. Sheppard, Chairman of the Westinghouse Owners Group.
5 4 ~
Described below are the six Critical Safety Functions as defined for. the McGuire units.
These six CSF's correspond to the five proposed in NUREO 0737, Supplement 1 as follows:
a.
- REACTIVITY CONTROL' is addressed by the Critical Safety LFunction, Suboriticalitv.
The variables monitored by the McGuire SPDS and the basis for their selection are described
~in section 3 23 1,. pages 3-94 and 3-95 of the attachment
- A",
excerpted from Duke Power Company, McGuire Nuclear Station, Emergency Procedure Guidelines Reference, Volume I, dated June 1984.
b.
' REACTOR ~ CORE COOLIN'G AND HEAT REMOVAL FROM THE PRIMARY SYSTEM' is addressed by two CSF's:.C.org Coolina described in section 3.23 2; and Heal Aink described in section 3.23.3. See pages 3-95, 3-96,~and 3-97 of Attachment 'A*.
. c.
' REACTOR COOLANT SYSTEM INTEGRITY' is addressed by two CSF's: Integrity described in section 3 23.4 beginning on page 3-97; and Inventorv described in section 3 23.6 on pages 3-100 and 3-101.
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- d.
. RADIOACTIVITY CONTROL' is addressed by the Containment CSF described in section 3 23 5 on pages 3-99 and 3-100.-
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- e.-
' CONTAINMENT CONDITIONS
- is addressed by the Containment CSF described in section 3.23 5 on pages 3-99 and 3-100..
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. MCGUIRE NUCLEAR STATION.
' SPDS RESPONSES.
January 31.-1985
-Page 3 REQUEST:
i 2.
Describe the basis on which the selected parameters are sufficient to assess the safety status of each of the five
-functions. listed above.
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RESPONSE
The McGuire SPDS is. based upon the six (6) Status Trees, one for
.each CSF, as defined in the Westinghouse Owner's Group Emergency Response Guidelines and specifically developed for and applied to the McGuire Units in Duke Power's " Emergency Procedure Guidelines for McGuire."
These plant specific guidelines are essentially the same as those i
developed for Catawba - Nuclear Station.
The acceptability of Duke's implementation of the Westinghouse Owners Group Energency Response Guidelines for Catawba is documented in Section 13 5.2 of " Safety Evaluation Report related to the operation of Catawba Nuclear Station, Units 1 and.2" dated December 1984.
- McGuire's Status Tree based SPDS takes credit for the validation programs.which were performed on the abcVe documents, and specif-
,ically,-those associated with the definition and selection of the six1CSF's and associated variables which are required to deter-mine the safety status of the plant.
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i 3 23 F-0 Critical heety Funation Status Trees 1
3 23 1-F-0.1 Suboriticality
.D==ator Trin Reanired The. Suboriticality CSF is designed to monitor the post-trip reactor status. This branch point results in a GREEN status during normal power operation.
Power Ran6e <M Following a reactor trip, nuclear power promptly drops to only a few percent of nominal, and then decays away to a level some 8 decades less.
Decay heat levels resulting from radioactive fission product decay are
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never more than a few percent of nominal power and also decrease in time.
Safeguards heat removal systems are sized to remove only decay heat and not significant oore power. The 55 level was abosen because it is clearly readable on the power range meters.
Nuclear power above 55, in a core that is supposed'to be shutdown, is considered an extreme challenge to the fuel clad / matrix barrier and a RED priority is warranted. The appropriate guideline for function restoration is FR-S.1, RESPONSE TO NUCLEAR POWER GENERATION /ATWS.
i-Intermediate Range SUR Zero or Negative j-At this point, power range flux has been determined to be not significant, so no extreme challenge exists.. However, a positive startup rate (SUR) in j
the intermediate range will shortly lead to power production if operator action is not taken, since no inherent feedback mechanisms exist'below the point of adding heat.
A positive SUR is considered a severe challenge.to the CSF and an ORANGE priority is. warranted.
The appropriate guideline for function response is FR-S.1, RESPONSE TO NUCLEAR POWER GE'!RRATION/
ATWS.
Source Range Energized This ' decision point is used to determine if further evaluation should be directed at the source range flux behavior, or back at tho' intermediate range channel indications.
5 Intermediate Range SUR More Negative Than -0.2 DPM Normally, - following reactor trip, ' intermediate range flux decays at a constant -0 3 DPM.
A rate of decrease less negative than -0.2 DPM (e.g.,
-0.1 DPM) is considered to represent an unsatisfactory condition' and.~ a i
YELLOW priority is warranted.
The appropriate guideline for function-restoration is FR-S.2, RESPONSE TO LOSS OF CORE SHUTDOWN.
If the rate of doorease is less negative than -0.2 DPN, then the CSF is satisfied.
i-Sauroe Range SUR Zero or Negative
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- Normally, following reactor trip, neutron flux decreases into the source range and stays there.
Typically source range count rate fluctuates,-and does not exhibit any sustained increasing trend.
Such a trend, as indi-3-94
cated by a positive SUR, is considered an unsatisfactory condition and a YELLOW priority is warranted.
The appropriate guideline for function restoration is FR-S.2, RESPONSE TO LOSS OF CORE SHUTDOWN. If source range
- SUR is zero or negative the CSF is satisfied.
3.23 2 F-0.2 Core Cooling
. Core Rwit TCn <1200*F Analyses of inadequate core cooling scenarios show that oore exit temper-ature greater than 1200*F is a satisfactory criterion for basing extreme operator action.
The average of the 5 highest oore exit 5 thermocouples should be reading greater than 1200* F.
Five has been chosen to allow margin for individual thermocouples failing high.
This temperature indicates that most liquid inventory has already been removed from the NC system and that core decay heat is superheating steam in the core.
An extreme challenge to the fuel matrix / clad barrier is imminent and a RED priority is warranted.
The appropriate guideline for functional response is FR-C.1, RESPONSE TO INADEQUATE CORE COOLING.
MC Syntem hhaeolina
>0* F r
If NC system subcooling is less than O' F, then SI flow should be maintained to the NC system to provide inventory makeup and the Core 4
F Cooling CSF is not satisfied.
Subsequent blocks check for inadequate or degraded core cooling conditions.
If greater than 0* F NC systea j
subcooling is indicated, then the CSF is satisfied.
f At f===t nam NC Pn=a aunnin, The REIS design has two ranges relevant for core cooling, lower range and dynamic head range, for use without NC pumps running and with NC pump :
running, %spectively.
This block determines which range should be used to assess - the Core Cooling CSF status in subsequent blocks.
If 'any NC E
pump is running, then the REIS dynamic head range should be used in
. assessing core cooling conditions.
If no NC pump is running, then the
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lower range should be used.
Core Ewit TCa <700*F If the. average of the 5 highest oore exit thermocouples indicates greater than 700*F, superheat at the core exit is indicated.- An inadequate oore oooling condition will exist if, in the next block, RYLIS indicates less than - <45%. (6 feet) collapsed liquid level in the core.
If core exit thermocouples indicate less _ that 700*F, then an inadequate core cooling -
condition does not exist - and the subsequent RVLIS check will assess whether_ a degraded core cooling condition has been reached.
f-RTLIS Lauer Range >415 (Core Rwit T-a-caturam Greater thma 700*F)
If RYLIS lower range is less than 435, then the core is uncovered and an -
. inadequate core cooling condition has been reached.
A RED priority is warranted and FR-C.1, RESPONSE TO INADEQUATE CORE COOLING, is the appro-1 priate guideline for functional response.- If RYLIS lower range is greater than 435, then a degraded oore cooling condition exists since the core 3-95
J exit temperatures are greater than 700* F from the previous block.
An ORANGE priority is. warranted and FR-C.2, RESPONSE TO DEGRADED CORE COOL-i ING, is the appropriate guideline for functional response.
i RVLTR Lavar Ranea >491 (Core Rwit Ta=naratures Lann than 700* F)
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If RVLIS lower range is less than 435, then the core is uncovered, but j
since core exit temperature has not reached 700* F, an inadequate core cooling condition has not been reached. A degraded core cooling condition exists.
An ORANGE priority is warranted and FR-C.2, RESPONSE TO DEGRADED l
CORE COOLING, is the appropriate guideline for functional response.
If RVLIS lower range is greater than 435, then only a saturated core cooling condition exists.
A YELLOW priority is warranted and FR-C.3, RESPONSE TO SATURATED CORE COOLING, is the appropriate guideline for functional response.
RVLTR Dyn==fa Head Ranma > Satnoint 4
If an NC pump is operating, then even under a highly voided NC system condition _the core exit thermocouples can be expected to indicate satu-j rated temperatures.
This block checks for NC system voiding less than i
approximately 25 percent which, if NC pumps are subsequently stopped, would ensure the core would initially be kept covered and adequately cooled. If RVLIS dynamic head range is less than the indioated setpoint a degraded core cooling condition exists.
An ORANGE priority is warranted and FR-C.2, RESPONSE TO DEGRADED CORE COOLING, is the appropriate guide-line for functional response. If RYLIS dynamio head range is greater than the indicated setpoint only a saturated core cooling condition exists.
A YELLOW priority is warranted and FR-C.3, RESPONSE TO SATURATED CORE COOLING, is the appropriate guideline for functional response.
3 23 3 F-0 3 Heat Sink j
wancow Ranea Laval in at L===t one SG >Gf (>18f ACC)
A level in the narrow range in any steam generator, including a ruptured one is sufficient to ensure.an adequate secondary inventory for a secon--
dary heat sink. If level is not in the narrow range, the operation of the feedwater systems will determine whether a loss of secondary heat sink is imminent.
. Total Anviliser Faadustar Flow to SGa >450 ann Total auxiliary feedwater flow of greater than 450 spa ensures that, in the absence of narrow range level in any steam generator, the capability of auxiliary feedwater to restore level and maintain a secondary heat sink is available.. If not, then an extreme challenge the heat sink CSF is imminent and a RED priority is warranted.
The appropriate guideline for functional response is FR-H.1, RESPONSE TO LOSS OF SECONDARY HEAT SINK.
Pra==ana in All Ana <1226 nmin In the event that pressure 'in any steam generator is greater than the.
highest steam line safety valve setpoint, then the steam generator design limit say.be exceeded and integrity may be challenged.
Also, there is no 3-96
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flow path in use removing energy from that steam generator. The Heat Sink j
CSF is not satisfied and a YELLOW priority is warranted. The appropriate
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guideline for functional response is FR-H.2, RESPONSE TO STEAM GENERATOR OVERPRESSURE.
w erow Manna Laval in All SGs <82f (<67f ACC) 7 An overfeed due to excess feed flow or a steam generator tube rupture may j.
lead to a high level in a steam generator.
This block checks all steam 1
generators to ensure identification since this condition may cause un-l wanted atmospherio releases or challenge steam generator integrity.
Note
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that.although the level in the affected steam generator may reach the top of the narrow range span, significant volume still exists before the steam generator fills with water.
The Heat Sink CSF is not satisfied and a YELLOW priority is warranted.
The appropriate guideline for functional response is FR-H.3, RESPONSE TO STEAM OENERATOR HIGH LEVEL.
I Pr====re in All SGm <1170 nmie i'
If any steam generator safety valve is open, then an unisolable heat j
removal path.is being used.
A better path is to use steam dump to con-i i
- denser or SM PORYs which are controllable and isolable.
Also, condenser 4
steam dump will not release steam to the atmosphere. The Heat Sink CSF is g
not satisfied and a YELLOW priority is warranted. The appropriate guide-line for functional response is FR-H.4, RESPONSE TO LOSS OF N01 MAL STEAM RRfRAMR CAPABILITIES.'
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Marrow sanna Laval in All SGs Mi (>181 ACC)
L Feedwater = should be maintained until all steam generators are in the narrow range unless a faulted steam generator is identified. Narrow range 4
level is reestablished in all steam generators to maintain synastric cooling of the NC system.
If any level is low, the Heat Sink CSF is not L
satisfied and. a YELLOW priority is ' warranted.
The appropriate guideline for functional response is FR-H.5, RESPONSE TO STEAM GENERATOR LOW LEVEL.
3 23.4 F-0.4 Integrity T - patura Daar==== in All Unid f==a <10# F in f==t 60 Minutaa 4
If ' the temperature decrease. in any cold leg has exceeded 100*F'in the previous 60 minutes, then there is s' potential concern for thermal shook.
If not,.then no other checks on rate-dependent limits are necessary. The remaining concerns are NC system overpressure and cold overpressure which will be checked in subsequent blocks.
If the temperature decrease has ezoeeded.100*F in the previous 60 minutes, the degree of cooldown must be assessed -' before a thermal shook concern can be identified.
This is checked in subsequent blocks.
All MC Swatan Pr=====a cnid f== T-naratura Points to si eht of T imit A
. The objective of Limit A is to provide a limit that indicates an extreme
-thermal shook condition.- The basis of this limit -is to prevent growth of-a flaw in the vessel.
If Limit A has been exceeded, then operator action f
'is necessary_to limit further NC system temperature dooreases or NC system 3-97
pressure increases.
A RED pricrity is warranted since an extreme chal-longe to the CSF is occurring and FR-P.1, RESPONSE TO IMMINENT PRESSURIZED THERMAL SHOCK CONDITION, is the appropriate guideline for functional response.
All MC Svates Cold T== Tm=neratures >150*F If any cold. leg temperature le less than 350"F, then operator action is necessary to minimize further NC system temperature decreases and NC system pressure increases. An ORANGE priority is warranted since a severe challenge to the function exists and FR-P.1, RESPONSE TO IMMINENT PRES-SURIZSD THERMAL SHOCK CONDITION, is the appropriate guideline for funo-tional response.
Pressurfman Pr===ura <2400 nai- (2250 naia ACC)
Since pressurizer pressure should normally doorease following an accident, this setpoint is not expected to be exceeded except for pressurization transients such as spurious safety injection or a power generation heat removal mismatch.
The pressurizer PORY lift setpoint is 2335 psig, so a pressure of 2400 indicates PORY malfunction, or other inability to handle the transient, and therefore a possible challenge to the pressurizer code safety valves.
All BC Svaten Cold fa-Tm=nerature >457'F The temperature region between 457'F and 350*F is intended to allow time for operator action to try ' to prevent entering a region of potential thermal shook.
In this region the CSF is not completely satisfied and a YELLOW priority is warranted.
The appropriate guideline for functional response is FR-P.2, RESPONSE TO ANTICIPATED PRESSURIZED THERMAL SHOCK CONDITION. If all NC system cold leg temperatures are greater than 457'F, then the Integrity CSF is satisfied.
Pr===uriump Pr===iina <2400 nmin (2250 nmin ACC)
./
Since pressuriser pressure should normally decrease following an aaoident, this setpoint is not expected to. be exceeded except for pressurization transients such as spurious safety injection or a power generation heat removal mismatch. The pressurizer PORY lift setpoint is 2335 psig, so a pressure of 2400 indicates PORY malfunction, or other inability to handle the transient, and therefore a possible challenge to the pressuriser code safety valves.
All MC Svaten Cold Ta-T- aarature >100*F In order to determine if cold overpressure is a concern, a check is made on whether NC system temperature has dooreased to below the temperature at which the pressurizer. PORY low setpoint should be enabled.
Subsequent blocks check if a cold overpressure condition exists.
MC Svaten Freasure <400 naig If the pressuriser PORY low setpoint should be enabled and NC system pressure exceeds 400 psig, then action may be necessary to minimize or 3-98
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doorease NC system pressure. The priority of action will be determined in subsequent blocks.
If NC system pressure nas not exceeded the cold overpressure limit, then the Integrity CSF is satisfied.
l All MC Swatam Cold T.=- Tm=neraturen >250*F f
If cold leg temperature in any NC system cold leg is less than 250*F and NC _ systes pressure is greater than 400 psig, then a severe challenge to the function exists and operator action is necessary to limit NC system pressure.
An ORANGE. priority is warranted and PR-P.1, RESPONSE TO IMMI-NENT PRESSURIZED THERMAL SHOCK CONDITION, is the appropriate guideline for functional. response.
If all NC system cold leg temperatures are greater than 250'F, then even though the cold overpressure limit has been _ exceeded (previous block),
there is no extreme or severe challenge to vessel-integrity, even at very high pressure.
A YELLOW priority is warranted, however, since the CSF is not satisfied.and FR-P.2, RESPONSE TO ANTICIPATED PRESSURIZED THElMAL SHOCK CONDITION, is the appropriate guideline for functional response.
~.23.5 F-0.5 containment 1
Contain= ant Prammure <15 naia If containment pressure is greater than design pressure, an extreme challenge to the containment barrier exists.
The challenge does not necessarily come from the pressure alone, but rather from the potential pressure spike which could result from a hydrogen ignition.
Also, above containment design pressure, leakcge my exceed design basis limits.
It is expected that containment pressure suppression equipment should be able to maintain pressure below design pressure.
If not, then operator action F
is necessary to ' check containment functions and a RED priority is war-ranted.. The appropriate guideline for function restoration is FR-Z.1, f
RESPONSE ':0 HIGH CONTAINMENT PRESSURE.
twatmi - nt pe==-uce < t omi e Pressure above 3 psig indicates a significant energy release to contain-l mer.and aerits prompt operator action to ensure operation of-oontainment pressure suppression equipment and performance of Phase B isolation. Such a pressure a:an requires Steam Line Isolation and is considered a severe challenge to the containeer.t barrier and an ORANGE priority is warranted.
L The appropriate gui M ine for function restoration is FR-Z.1, RESPONSE T0 p
HIGH CONTAINMENT PRESSURE.
Containannt Hydrogen Connantration <0.51 Appreciable accumulation of hydrogen gas inside containment is not ex-pooted except for, inadequate core cooling scenarios.
When significant amounts of hydrogen are generated by the metal-water reaction in the core, I
the gas may be released into the containment atmosphere more quickly than the electrio hydrogen reocabners can remove it.
In this case it is important to have an anticipatory hydrogen concentration setpoint -to provide navinum opportunity for the various sitigation systems to reduce the.ooncentration before it reaches flammability limits ubich would cause 3-99
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a containment pressure integrity concern due to a hydrogen burn.
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r'antni n==nt' h=n Laval <11 ft.
High energy line breaks could result in a large volume of water being pumped into containment.
As the water level rises, it might threaten the availability of equipment required for long term cooling of the core and/or. containment.
Such a high water level is considered a severe challenge to the containment barrier and an ORANGE priority is warranted.
The appropriate guideline for function restoration is FR-Z.2, RESPONSE TO CONTAINHENT FLOODING.
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Cantni n= ant Radiation Manitors <tR/hr Normally, containment building radiation lovsla are fairly low and con-stant.
However, during an.aocident, significant radioactivity may be released 'into the containment atmosphere.
In-containment systems are available to filter and scrub the contaminants from the atmosphere, and radiation alone does not represent a threat to containment integrity.
This is considered an unsatisfied condition and a YELLOW priority is warranted.
The -appropriate guideline for function restoration is FR-Z.3,
- RESPONSE TO HIGH CONTAINNENT RADIATION. If containment radiation monitors are <3R/hr, then the CSF is satisfied.
- 3.23.6 F-0.6 Inventory Pr===nciume Laval (oM (<80f ACC)
This decision point allows proper resolution of the actual inventory condition in. subsequent decision blocks..If pressurizer level is above a
the normal operating range, the next decision block determines if it is j
due to excess inventory or voids in the vessel..If level is not-high, then.further questions check for low level and voids in the vessel.~
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RYLTA DR Tadiantes >07f and Stahle (Pr===uriner Laval SoM f>80f ACC)
Having -already determined that pressurizer level is high, this question tries to define the cause.
If the upper head region is full, then' the problem is simply one of excess inventory; the Inventory CSF is considered
. not satisfied and a YELLOW priority is warranted.
The appropriate guide-
'line for function restoration is FR-I.1, RESPONSE TO HIGH PRESSURIZER.
LEVEL.
If the RYLIS does indicate voids in the upper head region, then j
. the problem is likely due to some type of bubble in that region.
Since
- the presence of.a bubble is considered an unsatisfied condition, a YELLOW
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priority is warranted. The appropriate guideline for function restoration
- is FR-I.3, RESPONSE TO VOIDS IN REACTOR YESSEL.
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Pr====pinap Level' >175 (>48st ACC)
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This block is entered after having determined that pressurizer level is not high.
If level is also not low,- then the pressuriser inventory is.
considered satisfactory and a further question is asked about reactor
- vessel level.
If pressuriser. level is not greater than the indicated
. setpoint, then the. problem is one of low inventory, with or without voids 4
in the vessel. The condition is considered an unsatisfied condition and a 3-100:
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YELLOW priority is warranted.
The Core Cooling Status Tree checks for
. more severe or extreme challenges to Inventory that also challenge the Core Cooling CSF.
The appropriate guideline for function restoration is FR-I.2, RESPONSE TO LOW PRESSURIZER LEVEL.
RVLTR UB Tndinaten > 711 and Stable (Prammiminar Level Determined to be Normal)
- Having -determined that pressurizer level is normal, the remaining inven-tory question relates to water level in the reactor vessel. If level does not indicate that the vessel is full, then some type of voids are present in, the vessel upper head.
The presence of a bubble is considered an unsatisfied cordition and a YELLOW priority is warranted. The appropriate guideline for function restoration is FR-I.3, RESPONSE TO VOIDS IN THE REACTOR VESSEL.
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