ML19327A666
| ML19327A666 | |
| Person / Time | |
|---|---|
| Site: | Zion File:ZionSolutions icon.png |
| Issue date: | 05/26/1989 |
| From: | Murley T Office of Nuclear Reactor Regulation |
| To: | Congel F, Miraglia F, Rossi C Office of Nuclear Reactor Regulation |
| Shared Package | |
| ML19327A642 | List:
|
| References | |
| TAC-73427, NUDOCS 8909140151 | |
| Download: ML19327A666 (1) | |
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6-NUCLEAR REGULATORY COMMIS$10N j
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i KEMORANDUM FOR:
Frank J. Miraglia, Associate Director t
for Inspection and Technicel Assessment, NRR l
C. Ernie Rossi Director I
Division of Operational Events Assessment, NRR l
Frank J. Con el, Director l
Division of adiation Protection and Emergenc_y Preparedness, NRR l
l FROM:
Thomac E., Murley, Director I
Office of Nuclear Reactor Regulation l
5 3UBJECT:
DIFFERING PROFES$10hAL VIEW 0F ROBERT 5.A. LICCIARM CONCERNING CONTAINMENT !$0LAT10N VALVES AT ZION l
i Enclosed is a memorandum from Mr. Licciardo to Dr. Murley, dated May 11,1989 l
expressing a Differin Professional View. In accordance with NRC Manual Chapter 4125 and NRR ffice Letter No. 300 dated March 24, 1989, you are hereby designated as the Panel to review and reconnend to the Director, NRR e
the appropriate disposition of Mr. Licciardo's Differing professional View.
If you deem it necessary, you may solicit input from other NRR technical staff l
or contractors.
In carrying out your review and formulating your Ncommendations to me, you should be guided by the Appendix to NRC Manual Chapter 4125 with special emphasis on Sections B.6 and 8.7.
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k Thomas E. Murley, m rector Office of Nuclear Reactor Regulation
Enclosure:
As stated cc:
J. H. Sniezek J. Larkins i
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May 11, 1989 I
MEMORANDUM FOR: Thomas E. Murley, Director L
Office of Nuclear Reactor Regulation I
FRON:
Robert 8. A. Licciardo, Reactor Engineer (Nuclear) -
Plant Systems tranch Division of Engineering and Systems Technology l
$USJECT:
O!FFERING PROFES$10NAL VIEni CONCERNING j
a) Issuance of SER to Zion 1/2 allowing full power
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operation with open 42" containment isolation l
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b) Methodology used for calculating related offsite doses, l
The writer submits a Differing professionalView(DPV)inaccordancewiththe provisions of NRC Manual Chapter 4125.
l This issue has arisen out of the safety Evaluation Report (SER) undertaken for the Zion Units 1 and 2 as prepared by the writers see Attachment.
The principal issue is the prudent and conservative calculation of the additions to offsite dose which may result from a LOCA at a facility during the use of i
open purge supply and exhaust valves at full power.
l The Ifeensee for Zion 1/2 has proposed full power operation of the facility i
with the 42' purge supply and exhaust containment isolation valves open tc a limited position of 50', and capable of isolation within seven (7) seconds l
of the cossencorent of a LOCA.
The writers $ER concludes that the 42' valves at Zion should remaiu closed in Modes 1, 2 3 and 4 because the consequence of the offsite dose to thyroid i
(from iodine),during a LOCA is unccceptably highu whole body has not been evaluated. The least value for the additional o fsite dose which may be o
proposedwithinthelicensingbasisis64.000renoverthefirstseven(7) seconds of the LOCA. Management staff has disagreed with the writer's methodology and conclusien and plans issuance of a separate SER permitting i
The writer requests non-issuance of the related SER the operation requested.
He also proposes probability of a generic action on other
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to the licensee.
facilities which have been granted such licenses based on the staff's current j
methodology.
i In general the management staff has adopted a criterion described in SRP BTp C5B 6d which is that providing the maximum time for closure of these containment isolation valves does not exceed 5 seconds (and by plant specific exception,upto15 seconds),thenthevalveswouldbeclosedbeforetheonset of fuel failure following a LOCA so that the only contribution to offsite dose is from RCS operational levels of fission product directly discharged into containment during this period, and then through the open containment isolation valves before closure.
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i Thomas E. Murley
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J qr in evaluating the consequence for Zion, the writer has used an alternate Criterion in BTP CSB 6 4 which states that:
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'The following analyses should be performed to justify the congainment purge system design:
An analysis of the radiological consequences of a loss-of-coolant accident. The analysis should be done fer a spectrum of break sizes, and the instrumentation and setpoints that will actuate the purge valves closed should be identified. The source term used in i
the radiological calculations should be based on a calculation under the terms of Appendix K to detemine the extent of fuel failure and l
l the comen91 tant release of fission products, and the fission product l
activity in the primary coolant. A pre-existing iodine s >1ke should be com.idered in determining primary coolant ertivity. Tw volume 6
l of cor.tainment in which fission products are mixed should be Justirted, and the fission products from the above sources should be 1
assumed to be released through the open purge valves during the maximum interval required for valve closure. The radiological I
consequences should be within 10 CFR Part 100 guideline values."
I the fuel performance over the 0-7 seconds j
UsingtheserelatedguidelinesforZion,(byinfringementofDNBRcriteria) l is detailed and shows that fuel failure l
occurs within i seconds of the comunencement of the LOCA, and together with other L
licensing basis responses including fission product release from the fuel gap and the thermal hydraulic conditions in the core, containment and discharge i
norale, result in a substantive discharge of fission products to the i
l environment of far greater consequence than are calculated by the staff.
j The relative consequences of these differing approaches are that whereas the i
staff methodology gives additions to offsite dose resulting in total doses within 10 CFR Part 100 limits, the alternate approach used by the writer shows a substantially increased offsite dose exceeding 10 CFR Part 100 limits, with completely unacceptable consequences to Public Health and Safety.
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The writer requests review of the Differing Professional View in a timely L
manner in accordance with the provisions of NRC Manual Chapter 4125.
- d>4 M Robert B. A. Licciardo l
Registered Professional Engineer California l
Nuclear Engineering License No. NU 001056 i
Mechanical Engineering License No. M 015380 cc:
J. Snter'ek D. Nuller S. Varga l
C. Patel F. Miraglia L. Shao A. Thadant I
J. Wermiel J. Kudrick
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May 11, 1989 f.
Attachment l
Docket Nos. 50-295 l
and 50-304 MEMORANDUM FOR: Daniel Muller, Director Project Directorate !!!-2 i
, Division of Reactor Projects !!!, !Y, V and Special Projects j
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FROM:
Jared 5. Wermiel Acting Chief i
Plant Systems Branch Division of Engineering and Systems Technology i
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$UBJECT:
0FFSITE RADIOLOGICAL CONSEQUENCES OF LOCA DURING I
CONTAl MENT PURGE PROPOSED IN TS CHANGES FOR ZION 1 AND 2
(
Reftrences Letter to N. R. Denton (NRC) from p. C. Leonard dated l
i February 2,1986,
Subject:
Zion Nuclear Power Station, i
Units 1 and 2 Proposed Amendment to Facility Operating j
License No. OPR-39 and DPR-48 Plant Nase:
Zion Nuclear Power Station, Units 1 and 2 i
L Licensee:
Cesmonwealth Edison Company TAC Nos.:
55417 and 55418 j
Review Status:
Complete i
ZionUnits1and2(Ceco)hasrespeaJedtoanNRCrequesttoproposeTSto primarily constrain operation of the large (42') containsent purge supply and exhaust valves on these unitsi see reference 1.
The forser Plant Systems tranch, Section A, of the Division of PWR Licensing F
A, requested Sectfon 8 of the same branch to review the offsite radiological consequences of this proposal.
The enclosed Safety Evaluation Report has been prepared by the technical reviewer initially assigned to this task, namely Robert 8. A. Licciardo.
The licensee's pro sal is to allow full power operation of the facflity with and exhaust containment isolation talves open to a the 42' purge supp limited position o 50', and capable of isolation within seven (7) seconds of j
the commencement of a LOCA.
lhe review concludes that the 42' valves at Zion shoulf remain closed in
{ ' T (cdes 1, 2, 3. and 4 because the consequence of the offsite dose during a LOCA is unacceptable hight whole body dose has not been from fodine)he least value for the additional offsite dose which may be proposed i
evaluated: T J
within the licensing basis is 64,000 ren over the first seven (7) seconds.
The conventional treatment of BTP CSB 6-4 which assumes that fuel failure does not occur over the first 5-15 seconds after a LOCA and thereby that only RCS and operating inventory of fission products is released to the containmen analysesforcontainmentresponse,andlicensingbasisrequirements(including criteria)forthecalculationfor,andtheoccurrenceof,fueldamageandthe i
quantification and treatmen' of resulting source terms.
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Daniel Muller
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i Cur SALP inlput is provided in Enclosure 2.
We consider our efforts og TAC l
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t Nos. 55417 and 56414 to be complete.
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Jared S. Wermiel, Acting Chief Plant Systems Branch Division of Engineering and Systems Technology j
Enclosures:
As stated a
cc w/ enclosures:
C. Patel
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CONTACT: R. Licciardo Xt0876 I
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J Daniel Muller :
Our $ Alp input is provided in Enclosure 2.
We consider our efforts os TA Nos. 55417 and $5418 to be complete.
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Jared $. Wermiel, Actin 9 Chief i
Plant Systems Branch j
Division of Engineering and Systems Technology i
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Enclosures:
i As stated cc w/ enclosures:
c C. Patel CONTACT: R. Licciardo X:0876 j
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.(e eeee sf s' SAFETY EVALUATION SY THE OFFICE OF WUCLEAR REACTOR REGULATION l
PLANT SYSTEMS BRANCH 1
0FFSITE RADIOLOGICAL CO M EQUENCE OF LOCA DURING CONTAINMitti PURGE f
ZION NUCLEAR POWER STATION, UNITS 1 AND 2 i
DOCKET N05. 50 295 and 50-304 l
1.0 INTRODUCTION
ZionUnits1and2(Ceco)hasrespendedtoanNRCrequesttoproposeT5to primarily constrain operation of the large (42") containment purge supply and exhaust valves on these units.
The former plant Systems Branch, Section A, of the Division of PWR Licensint A, requested Section 9 of the same branch to review the offsite radiologice 8
consequences of this proposal.
l 2.0 EVALUATION j
i Sachround review shows that the facility was evaluated on the basis of r sally closed purge valves w that these ec,nsequences were never included
..t the Zion SER. Further, that a letter from Westinghot:se LW) to Comonwealth i'
LOCA and Cortainment Purge * (Ref.1976 on the subject of 'Of? Tite Doses D Edison Company d.ted October 22 2)hasneverbeenevaluatedbytheNRC.
subsequent to the TM!-2 event, the operability and automatic control of these valves war evaluated lesding to the request for the required 75 Radiological 3)whichwas l
intended to be resolved in a subsequent probabilistic risk assessment which definitivelyexcludeditfromconsiderationwithoutanyjustification(Ref.4).
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uses a.i RCS The W analyses undertaken under Comonwealth Edison instruction,f the accident operational inventory of W uc/gm equivalent ! 131 at the time o with a resulting site boundary thyroid doso due to iodine (during closure of the valves), of 52 rom, and which added to the cantainment leakage dose of 123 rem gives a total 175 rem which is within the 10 CFR 100 limit of 300 rom.
i The total iodine inventory of the RCS is assumed to be released into containment en initiation of the LOCA: a 505 plate out is assumed leaving the residual 505
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as part of containment inventory for discharge out tnrough both fully open L
containment purge lines for a total of seven (7 seconds).
l However, when' reviewed agaisist the BTP CSB 6-4, Item B.S.a requires that:
'The source term used in the radiological calculations should be based on a calculation under the terms of Appendix K to detemine the extent of l
l fuel failure and the concosmitment release of fission products, and the fission product activity in the primary coolant.'
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Mr Further: $RP 4.2 identifies fuel failure with infringement of DNBR criteria, j
with the related requirement that gap activity be considered as part of i
the source ters, and Regulatory Guide 1.77 recommends that under similar circumstances, gap activity should be assumed at 105 of core activity. Fuel i
i damage criteria also includes the occurrence of center line melting'with measures of additional activity release also guided by Regulatory Guide 1.77, l
but the lion SAR showc this does not occur.
j RevisingthesourceterstoAppendixKcalculations[inwhichallfuelgoes j
to DNBR in i second) with related release of all gap activity into containment, i
with limited blowdown to offsite during the related 7 seconds closurv time and abstnt a 50% plate out of iodine as can be interpreted from the above referenced item B.6.a. increases offsite dose due to containment purge above l
rem and would thereby bv completely unacceptable.
by a factor of 3400 to 176 000 Limiting the purge line valves to an opening of 50' could reduce offsite dose to 64,000 rem and represents the least value which may be proposed within the licensing basis.
Note: The BTP CSB G-4 proposing that valve closure within 5 seconds will ensure purge valves are closed before the onset of fuel failures has since i
been extended by the staff on a plant-specific basis to 15 seconds. Further, the writer cannot find any safety evaluation report supporting these positions.
These positions cannot be sustained for Zion since a) DN8R infringement (from Appendix K calculations) and hence fuel failure and gep activity release [Ref.
SRP 4.2) of 10% of core inventory (Ref. Regulatory Guide 1.77) occur within i second of the initiation of the LOCA, b) related maximum clad temperatures of i
1750'F occur issnediately and never reduce below 1400'F, c) RCS pressure in the i
region of the core rapidly reduces from 2250 psia to 900 psia in 7 seconds increastog potential pressure drop across the cladding for release of gap d) the massive bulk boilir.g and blowdown activity to the RCS inventoryltimately discharges 270,000 lbs of RCS inventory surrounding the failed fuel u into the contairment at 7 seconds into the event increasing containment pressure from 0.3 psig to 23.8 psig (in these 7 seconds), ard e} causes 15,000 lbs of l
the resulting containment inventory to be discharged to the environment through 2x42" fully cpen lines, or 5400 lbs for the same lines with valve closed to 50'.
3.0 CONCLUSTON the consequences of the offsite dose to thyroid (from iodine} and 4 becaus The 42' valves at Zion should remain closed in Modes 1, 2 3 during a LOCA is unacceptably high; whole body dose has not been evaluated. The least value i
for offsite dose to the thyroid which may be proposed within the existing licensing basis is 64,000 res.
The conventio'nal treatment of BTP C$8 6-4 which assumes that fuel failure den not occur over the first 5-15 seconds after a LOCA and thereby that only PCS operating inventory of fission products is released to the containment, and then to the environmerit, cannot in general be sustained against thermal hydrauite analyses for containment response, and licensing basis requirements (including i
criteria) for the calculation for, and the occurrence of, fuel damage and the l
quantification and treatment of the resulting source terms.
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i p,e fa References j
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I 1.
Letter from P. C. Blond (CECO) to H. R. Denton (NRC)
Subject:
Zion, Units 1 and 2, Proposed Amendment to Factitty Operating Ldeense i
Nos. DPR-39 and DPR-48 dated February 21, 1986.
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2.
Letter from R. L. Kelley LW) to C. Reed (Ceco):
Subject:
Offsite Dose During LOCA and Cont 7a nment Purge, dated October 22, 1986.
3.
Letter to L. D. De1 George (CECO) from 5.A. Varga (NRC)
Subject:
Generic Concerns of Purging and Venting Containments, dated September 9. 1981.
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" Evaluation MemoforF.H.RobinsonfromR.W. Houston $.
Subject:
4.
of the Riek at Zion,' dated August 14,198 i
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$PLB SALP INPUT Units 1 and 2 I
Zion Nuclear Generating Stations, Operation Plant Name:
Containment Purge and Vent Valve i
Subject:
TAC Nos.:
55417/8
$9senary of Review /!nsoection Activities The licensee provided an evaluation of offsite doses undertaken in 1976. This was undertaken with a methodology and source term chosen by the licensee. The licensee did not present results from altarnative more detailed methodologies whicia could be considered enforceable under existing regulatory positions and i
the related circumstances.
l Narrative Discussion of Licensed Performance - Functional Area The sinille only methodology used by the licensee is not an acceptable approach for est< mating doses under the proposed circumstances and especially since alternate detailed evaluations required by the SRP give greatly increased values beyond 10 CFR Part 100 limits. A prudent approach would have r
recgnized the deficienc';es and risks in the single methodology adopted with resulting substantively different recountndations to ensure pubite iealth and safety.
Author: Robert B. A. Licciardo Date:
May 11, 1989 k
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