ML20107M775
| ML20107M775 | |
| Person / Time | |
|---|---|
| Site: | Beaver Valley |
| Issue date: | 11/08/1984 |
| From: | Woolever E DUQUESNE LIGHT CO. |
| To: | Eisenhut D Office of Nuclear Reactor Regulation |
| References | |
| 2NRC-4-189, NUDOCS 8411140258 | |
| Download: ML20107M775 (5) | |
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'Af 4 )78 5141 (412) 923-1960 N'Jctear Construction Division econ (412) 787 2629 Robinson Plaza, Building 2, Suite 210 F,ttsburgh, PA 15205 November 8, 1984 United States Nuclear Regulatory Commission Washington, DC 20555 ATTENTION:
Mr. Darrell G. Eisenhut, Director Division of Licensing Of fice of Nuclear Reactor Regulation
SUBJECT:
Beaver Valley Power Station - Unit No. 2 Docket No. 50-412 Identification of Backfit Requirement Number 29 Gentlemen:
In Draf t Safety Evaluation Report Section 2.3.4 (attached), the NRC identified that the applicant unde res t imated atmospheric dispe rs ion cond-tiona at the Exclusion Area Boundary (EAB) for assessments of the conse-quences of radioactive releases for design basis accidents in accordance with the requirements of 10CFR100.
The BVPS-2 atmor pheric dispersion conditions at the EAB were calcu-lated using the guidance of R.G.1.145.
In subsequent conversations with the NRC staff on August 15, 20, 23, and September 19, and in a meeting at the NRC on September 24, 1984, the methodology and information (data) used to calcu-late atmospheric dispersion conditions were discussed.
At the September 24, 1984 meeting, the following areas were identified as being the possible rea-sons for the dif ferences in the X/Q values calculated:
1.
Meteoroingical data used by the staff was not the correct data.
2.
Distance to the EAB used by the staff was incorrect.
3.
The staf f's interpretation of the smooth curve used to form an upper bound of computed points as described in R.G.
1.145, Section 2.1.1 is overly conservative.
Subsequent to the Sep teniber 24, 1984 meeting, the applicant has submitted to the staf f the " correct meteorological data" and " distance to the EAB" to be used in their X/Q calculations.
The staf f has recalculated the X/Q value using the meteorology data, but has not used the correct distance to the EAB.
On November 2, 1984, the staf f informed the applicant that the X/Q's would not be recalculated because it is the staf f's opinion that the X/Q values would not be low enough to give suf ficient margin in calculating dose project ions at the EAB and that the applicant should use other methods (extend EAB in northwest sector) to reduce the X/Q values.
8411140258 841108 DR ADOCK 05000
Unitud Stctss Nuclect Ragulctory Commission Mr. Darrell G. Eisenhut, Director Page 2 DLC has:
1.
Calculated the X/Q values using the guidance of R.G. 1.145 with resultant dose project ion values less than 10CFR100 require-ments.
2.
Calculated the X/Q values using the more conservative straight line method (PAVAN Code) with resultant dose projections less than 10CFR100 requirements.
3.
Ran the NRC test case for the PAVAN Code as described in NUREG/
CR-2858 to demonstrate proper funct ioning and use of the com-puter program.
Since in the above cases (1 and 2), the doses were less than 10CFR100 requirements, there appears to be nc regulatory basis requiring a
change to the EAB to achieve even lower doses.
Therefore, unless the basis for this new requirement can be demonstrated as an existing regulation, the controls of 10CFR50.109, GNLR 84-08, and NRC Manual Chapter 0514 identify the requirement as a backfit.
DLC requests that the proposed requirement be submitted to NRC management for approval in accordance with the O f fice of Nuclear Reactor Regulation (NRR) procedure for management of plant specific backfitting, prior to transmittal as a licensing requirement.
DUQUESNE LIGHT COMPANY
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E. J. WooleVe Vi Presi,'t TJZ/nml Attachment
.Mr. H. R. Denton, Director (NRR) (w/a) cc:
Mr. G. W. Knighton, Chief (w/a)
Mr. B. K. Singh, Project Manager (w/a)
Mr. G. Walton, NRC Resident Inspector (w/a)
1 contained in Section 2.3.3 of the St anda rd Revi ew Pla n.
Although the applicant maintains that the current instrumentation and da ta reduction procedur es c onf o rm to the recommenda tions of Regula to ry Guide 1.23, "0nsite Meteorological Programs," the staff is con-c erned about t.he representativeness of the data collected at the new towe r Location.
The current meteorological measurements program has provided data to represent onsite meteorological conditons as required in 10 CFR Part 100.10; howeve r, t he staff is continuing its evaluation of the adequacy of the j
proposed upgrades to the program.
Nevertheless, the staff concludes that the historical site data provide a reasonat te basis for making preliminary estimates
. of atmospheric di spe rsion condi tions fo r estima ting consequences of design basis accident and routine releases from the plant.
l 2.3.4 Short-Ters (Accident) Diffusion Estimates l
l To audi t the applicant's estimates, the staff has l
pe rf o rmed an independent, preliminary a ssessment of i
s ho rt-t e rs (Less than 30 days) accidental releases f rom buildings and vents using the direction-dependent atmospheric di spe rsion model desc ribed i n Regulatory
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Guide 1.145, "Atmosphe ric Di spe rsion Models for l
t Potential Accident Consequence Assessments at Nuclear Powe r Pla nt s," wi th c onside ra tion of increased lateral di spe rsion during stable condi tions accompanied by Low wi nd speedu.
Five years (J a nua ry 1977-De c emb e r 1981) of onsite data available to the staff on magnetic tape, which had 92% data recovery, were used f o r thi s evalua tion.
Vind speed and wind direction data were based on measurements at the 10.7 m levet and a tmospheric s tabili ty wa s defined by the vertical t empe rature g radi ent measured between the 45.7 m and 10.7 m levels.
A ground-level' rele ase wi th a buitding 2
wake factor, CA, of 800 m was assumed.
The relative concentration (X/Q) f o r the 0-2 hour time pe riod wa s
~3 deteininsd to be 2.4 x 10 sec/m at an exclusion area boundary distance of 455 m in the northwest sector.
The X/t values for appropriate time periods at the outer bounda ry of the low population zone (5800 m) are:
Time Period Y/0 (sec/m )
10 '
~
0-8 haurs 8.1 x 8-2 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> 5.7 x 10 '
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1-4 days 2.6 x 10 '
~
-6 4-3 0 day s 8.8 x 10
. Nd 0
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.._.,_,.m.
+
The applicant has cat cula ted a Lower (about 40%) X/Q value f o r t he O'-2 hou r t ime p e ri od a t the exclusion area boundary than that calcutated by the staff.
The X/G values calculated by the applicant fo r the va rious time pe ricds at the LPI di stance within 15% of those catculated by the staff.
These smalL dif ferences may be attributed prima rily to di f f e rent pe riods of meteorological data record used by the staff and the applicant.
Based on the above preliminary evaluation perf o rmed i n accordance with the criteria contained in Section 2.5.4
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of the Standa rd Revi ew Plan, the staf f concludes that L
the appli cant has unde restima ted a tmospheric di spe rsion conditions at the ex clusion area bounda ry fo r assess-ments of the consequences of radioactive releases for design basis accidents in accordance with the requirements of 10 C FR Pa rt 100.11.
The atmospheric di spe rsion estima tes provided above which we re independently eatculated by the staf f have been used by the staff in an independent pr eli mi na ry assessment of the consequences of radioactive celeases for design basis accidents.
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