ML20214A357
| ML20214A357 | |
| Person / Time | |
|---|---|
| Site: | Calvert Cliffs, 05000000 |
| Issue date: | 05/18/1986 |
| From: | Montgomery B BALTIMORE GAS & ELECTRIC CO. |
| To: | |
| Shared Package | |
| ML20214A317 | List:
|
| References | |
| RTR-NUREG-1150 NUDOCS 8705190410 | |
| Download: ML20214A357 (16) | |
Text
. ~ >
'sr-- .'l ,. ; _ , _ , , y. ,_
-r
- L I cm-f ^,A ~ tV i
^
BALTIMORE l GAS AND ELECTRIC THE CASE FOR A REDUCED EPZ t
by Bruce Montgomery Senior Engineer Baltimore Gas and Electric Company Presented at The Atomic Industrial Forum's Topical Conference on Reducing the Cost"of Nuclear Power New Orleans, Louisiana May 13-21,1986 l
1 I
8705190410 870319 i PDR NUREG '
PDR t
1150,C ,, -
1
4 ACKNOWLEDGEMENTS The author of this paper would like to acknowledge the contributions of - the Stone & Webster Engineering Corporation in the area of source term technology and NUS Corporation in the area of offsite consequence analysis, without which Baltimore Gas and Electric Company's initiative to reduce the emergency planning zone would not have been possible.-
O 9
9 9
- . ._ ,m., , -
.~_
l l
I. INTRODUCTION Several problems stand between today's commercial nuclear power industry and the vigorous, growing industry which many still envision for the future. Among these, the problems that are associated with emergency planning stand out prominently.
In the relatively short period since expanded requirements for emergency planning were promulgated by the federal government in 1981, nuclear utilities have ' expended substantial resources in this area. The difficulties associated with putting a viable emergency response plan in place'at a nuclear- power plant has often strained whatever working relationships utilities had previously established with local and state governments and has introduced yet another organization, the Federal Emergency 1
{ Management Agency (FEMA), into the licensing : process. In a few cases, these i
difficulties have been and continue to be so severe that they have effectively blocked some plants from entering commercial operation.
An element of today's emergency planning requirements which lias been especially problematic is the requirement that the plume exposure emergency planning zone (EPZ) have a radius of ten miles. The development of an emergency response plan i
which encompasses such a large geographic area is a challenging process in any case, and can easily become difficult or near-impossible to implement in those instances where the planning radius cuts across several political boundaries, thereby making the ' plan hostage to the willing participation of a multiplicity of townships, counties, and sometimes even states.
Furthermore, residents living in the general area of a nuclear power plant l may come to view the 10-mile EP:: as a symbol of their fear over the dangers of nuclear l power instead of the symbol of security and protection that emergency plans were l
4 3
. _ . ~ .,_.;s, _ . ,-- , ,.~..,a.. . , - _ . _ . , , - , . , - , , , - _ - . . . _ , _ . , .. . . , - - . , . , . - . = = ~,._e. . . . , -
originally meant to be.- If left uncorrected, this situation will be a source for continued '
problems at existing plants and will make it difficult to find new sites in the future that -
are suitable for nuclear energy.
Today's problems notwithstanding, there is reason to be optimistic about the prospects for changes in emergency planning requirements, even in consideration of the recent accident at Chernobyl Unit 4 in the USSR. The nuclear industry now possesses a vastly improved understanding of !!ght-water reactor severe accident phenomena and containment behavior that is not likely to be altered by the Chernobyl experience. This . .
Information shows that the offsite radiological consequences of severe accidents.are far i
less than were originally anticipated when the present emergency planning requirements were adopted. Baltimore Gas and Electric Company (BG&E) believes that it is time to utilize this new important technology in reducing the cost of nuclear power in the area of
. emergency planning. ,
To this end, BG&E submitted an application to the Nuclear Regulatory Commission (NRC) on November 13,1985, which requests an exemption from present emergency planning requirermnts. Specifically, BG&E's app!! cation proposes a reduction
~
in the plume exposure EPZ from a radius of ten miles to two miles. This paper describes '
the philosophy and technical approach employed by BG&E in its effort to reduce the EPI.
II. PRESENTING THE CASE FOR CHANGE 1
Calvert Cliffs Units 1 and 2 are twin 850 MWe pressurized water reactors i
. housed in large dry containments of post-tensioned design. The ll35-acre plant site is located on the western shore of the Chesapeake Bay in southern Maryland approximately 45 miles southeast of Washington, D.C., which is the nearest large population center.
4
'l The demography of the plant's immediate surroundings can be characterized as rural and agricultural, with projections for a low rate of population growth through the year 2020. ,
Presently, BG&E's plume exposure EPZ for Calvert Cliffs consists of the standard 10-mile radius circle. The majority of the zone lies in Calvert County with portions touching Dorchester County on the eastern side of the Chesapeake Bay and St.
Mary's County to the southwest. It is estimated that 30,000 people reside in this area.
The population within radil of five and two miles of the plant is approximately 5,000 and 300 people, respectively.
In all, BC&E's emergency response plan for Calvert Cliffs includes
~
involvement by six separate agencies: the NRC, FEMA, and the Emergency Management and Civil Defense Offices of the State of Maryland and the three counties mentioned above. In its present form, this plan has now been in effect for five years and has i
consistently received passing grades from the NRC and FEMA in the numerous drills that have been conducted to date. More importantly, the concept of emergency planning appears to be tolerated if not well-received by local residents.
The requirement for a 10-mile EPZ can be found in 10 CFR 50.47,10 CFR 30.54(s) and 10 CFR 50 Appendix E, which state that:
' " Generally the plume exposure pathway EPZ for nuclear power plants shall consist of an area about 10 miles (16 km) in radius and the ingestion pathway EPZ shall consist of an area about 50 miles (30 km) in radius."
i Footnote I to 10 CFR 50 Appendix E cites NUREG-0396, " Planning Basis for the Development of State and Local Government Radiological Emergency Response Plans in Support of Light Water Nuclear Power Plants", dated December 1973, for a discussion 5 .
. . ~
1 4-,1 of EPIs. As the planning' basis document for the entire concept of emergency response plans, it represents the primary published source of understanding of the philosophy and .
underlying purpose of the existing rule. Specifically, NUREG-0396 states (on page 2i):
"The . establishment of Emergency Planning Zones of about 10 miles for the plume exposure pathway . . .-is sufficient to scope -
the areas in which planning for the initiation of predetermined.
protective action is warranted for any given nuclear plant."
4 L
- NUREG-0396 concludes that the. objective of emergency response plans .
should be to provide dose savings for a spectrum of accidents that could produce offsite i
doses in excess of the protective action- guidelines (PAGs). . Dose savings would be.
achieved by protective actions within the plume exposure path'way EPZ, so that the doses in question would not be received by Individuals. Therefore> the underlylng purpose of- .
i the plume exposure pathway EPZ is to establish an area .within which planning -of s
predetermined actions would be expected to result in dose savings comparable to those discussed in NUREG-0396. It should be noted that NUREG-0396 expressed caution in the use of PAGs in establishing requirements for emergency response p!ans. . The repo_rt states that the nature of PACS is'such that they cannot be used to ass'ure that a given level of exposure to individuals in the population is prevented. In any particular response 4
situation, a range of doses may be experienced, and some of these doses may well be in excess of the PAG levels and clearly warrant the initiation of any feasible protective 4
actions. This does not mean, according to the authors of NUREG-0396, that doses above PAG levels can be prevented or that emergency response plans 'should have as their objective preventing doses above PAG levels. i i
i In reaching the conclusion that a plume exposure pathway EPZ of about 10 miles is sufficient, NUREC-0396 cites technical data contained in Appendix ! to that
^
report, entitled " Rationale for the Planning Basis." Appendix ! evaluated the offsite 1
1 6
i
- - . . - . - , . , , , , . -- . - . , , _ , - , . ~ ,--mi,,-_4--,7.,, .,msm.m,......cr.m.. .-mm.m, , , , ,,,,..,1- , -- x , em - . . , - , - - - - ,--,,A
consequences of Design Basis Accidents (using FSAR accident source terms) calculated for a'large number of nuclear power plants, which in turn were related to the PAGs (see -
Figure I-8 of Appendix ! to NUREG-0396) as a function of distance.
The approach presented in Figure I-11 of Appendix I, however, was clearly the primary influence for recommending a planning basis incorporating a 10-mile EPZ. In developing this figure the authors of NUREG-0396 plotted the probability of receiving a whofe body dose of 200 rem versus distance from the release point. The WASH-1400 Reactor Safety Study, which contained the most current source term information that i
was available at the time, was used as input to the figur'e. The figure shows that the i
probability of receiving 200 rem, that'Is, an exposure level at which significant early injuries may start to occur, drops off sharply at about 10 miles.
)
Given that this 200-rem curve played a major role in the recommendation 'for a 10-mile EPZ, it seemed apparent that a reasonable case for redefining the EPZ radius could be presented based to a large extent on a revised 200-rem curve utilizing updated source terms.
I
{ Having decided to present such a case, BG&E selected the exemption process i defined under the new rule for specific exemptions (i.e.,10 CFR 50.12) as the chief medium for pursuing EPZ reduction.10 CFR 50.12 states that a specific exemption from i
an existing regulation can be granted to a licensee if one of the following circumstances
~
is present 4
o Comp!!ance would conflict with another rule; l
4
- o Compilance would not serve the underlying purpose of the rule; i
. y ; -
1 o Compliance would cause undue hardship to the utility;
- o Compliance would be adverse to safety; or o There are present new material circumstances not considered when the rule in question was adopted. ,
BG&E's licensing approach, quite simply, is to show that an exemption from the 10-mile EPZ ' requirement is warranted because new material circumstances are present (i.e., new source terms) which allow a reasonable case to be presented that the dose savings from a 2-mile EPZ are comparable to the savings which were previously thought to be achieved at 10 mkles. Therefore, compliance with a 10-mile EPZ requirement would not serve the underlying purpose of the rule.
To supplement this licensing approach from a procedural standpoint, BG&E also requested (on January 10, 1986) that the exemption request be processed by the NRC as a license amendment. This step was taken in recognition of the significance of EPZ reduction and its impact on the overall emergency response plan. The advantages of the license amendment process are that, among other things, it clearly delineates requirements for oublic notification and public participation in the course of reaching a regulatory decision.
!!!. DEVELOPING NEW SOURCE TERMS FOR CALVERT CLIFFS The timing of BG&E's decision to pursue an EPZ reduction initiative was based in large degree upon a judgment that new source term technology, particularly for 8
a ..
, y r
! large dry containment PWRs, is mature enough to apply. The nature of the questions and uncertainties which remain to be investigated in this area are such that they appear to be ;
rebuttable from the standpoint of either being inapplicable to the Calvert Cliffs design r
~or inconsequential to the type and quality of radionuclides calculated to be released .l 1
offsite for any particular accident sequence.
4 j , To minimize involvement in the ongoing, highly technical source term debate,-
1 i
. BG&E decided to rely as much as possible on widely accepted data. After a careful study f of available source term work, a decision was made to reference the Surry source terms I presented in NUREG-0956, Draft Report for Comment, " Reassessment of the Technical ,
4
. Bases for Estimating Source Terms", dated July 1985. This was done by selecting the i dominant accident sequences for Calvert Cliffs with the aid of the NRC's Interim i
j Reliability Evaluation Program (IREP) Report (NUREC/CR-3511), and then comparing
], Calvert Cliffs design features with those of Surry to show that for the same sequence',
{. there is no reason why the Surry source term should not apply to Calvert Cliffs. A q
t comparison of plant design features which have been shown to be of importance I regarding source terms is provided in Table I for Surry, Zion, and Calvert Cliffs.- i 1
f i
This approach was successfully used to evaluate in-containment and impaired -
1 containment sequences for Calvert Cliffs without the need for new analysis or research.
However, because of other design differences this approach was not feasible for i
! evaluating interfacing system I.OCAs, otherwise known as the containment bypass or "V" j sequences. Therefore, two Calvert Cliffs-specific V-sequences (high/unsubmerged and i
- low / submerged) were selected and modeled explicitly. l i '
i f The results of this two-step analytical approach yielded the source terms l 4
- shown on Table 2. Except for noble gases, these source terms are less than one-tenth of l l
! WASH-1400 values. '
i '
9 .
~ = ,
- j. -
}- IV. . SELECTING AN APPROPRIATE EPZ RADIUS -
- l. ,
p ,
The offsite consequences frem the .in-containment and containment bypass sequences were calculated as a function of distance from the plant using Calvert Cliffs-specific meteorological data. Normal activity (i.e., no evacuation) was assumed for a f
24-hour period. . The 'resulting data were summed to yleid the total probability of receiving a 200-rem whole body dose versust distance. Thlis curve was then superimposed on the corresponding 200-rem curve from NUREG-0396 which, as was discussed earlier, i
assumed WASH-1400 source terms. As can be seen by inspection of Figure 1, the Calvert . ,
j 1
Cliffs dose curves drop off substantially at a distance of about 2 miles. In comparison, t
the NUREG-0396 curve has a discernible " knee" at about 10 miles. In addition, the tota!
[ probability of experiencing radiological releases that could cause offsite exposures in the range of 200 rem was shown to be considerably lower than the NUREG-0396 4
k- probabilities. Based on these results, BC&E concludes that the underlying purpose of the plume exposure pathway EPZ rule is achieved at a radius of two miles at Calvert Cliffs.
} V. .
IMPACT ON THE CALVERT CLIFFS EMERGENCY RESPONSE PLAN i
a The actual impact of. reducing the EPZ to a two-mile radius would depend i largely on the extent to which St. Mary's and Dorchester Counties desired to remain in l
the Calvert Cliffs emergency plan. BG&E has taken the position that even in winning the t
case for a two-mile EPZ, BG&E would be willing to discuss retalning some or all aspects l of the present plan in those areas that would otherwise be excluded, depending on the '
, desires of the local governments involved. For example, in one case a county !
government that would otherwise be excluded may elect to remain in the plan with only a t
few changes, such as some new agreement regarding the responsibility for upkeep of b
10 t
4 6 s '
,,.w.., . . , , , . , ,.,e.,-,,-c,,- ----,-------n-- - -- ,,-r-n, , _ , , .,~.-,~-r,-mm-r-.e-~m.. , , . , - - - --
,,----,ww .-,~w, ,-- ,---,r,,e-,,,-m.,w, ,
_. . .._. _ _ _ _ _ . . ~ . . _ ._. _ _ . . . _ . _
'.. i -
L sirens and other emergency response equipment. Elsewhere, a county government may ,
elect to be " dropped" from the aspects of tne plan concerning the plume exposure ,
pathway and simply continue participation in the plan by virtue of still being within the ~
t 50-mile ingestion pathway EPZ. In this case, BG&E has expressed a willingness to discuss i
a transfer of ownership of emergency response equipment to this county so that it may
)
be distributed more evenly throughout the county for general civil defense purposes.
- i i
By far the most significant impact on the plan itself would be that the NRC's and FEMA's purview over the plan would end at a distance of two miles. Thus, from a.
l federal perspective, the scope of mandatory pre-planning efforts for the Calvert Cliffs plume exposure pathway would be reduced from three counties to only one county and from 30,000 people to only 300 people. This in turn will simplify emergency planning -
efforts by focusing resources on a smaller area and should further increase the pub!!c's
, confidence in the plan's feasibility.
VI. CONCLUSION: WINNING THE CASE Up to this point, this paper has only discussed the nature and potential j 1mpacts of BG&E's proposal to reduce the EPZ. The present review status of BG&E's i
{ application at the NRC certainly merits some discussion, as does its prospects for
- approval. '
On February 14, 1986, the NRC formally responded to BG&E by indicating that, in their view, an application to reduce the EPZ is premature. This response was made in light of the fact that BG&E's application referenced source term Information from an NRC report (NUREG-0956) that was still in draft form. The NRC stated that the app!! cation would not be considered until all remaining questions concerning source terms had been resolved and NUREG-0956'had been published in final form.
}
, 11 L____.- , _ . _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ . _ - _ .
. - .. -. - . . .. - = - . . - . _-.
L. i
~
i 1
With the knowledge that NUREG-09% was scheduled to be published in July
- j .1986, BG&E sent a letter to the NRC on March 27,1936, indicating a willingness to await
, the report's arrival.
I i -
A considerable amount of interest in the BG&E application and its well-being has been expressed by members of both houses of Congress, particularly by those ,
committees involved in national energy policy _ and oversight of the NRC's operating
~
budget. In response to one particular inquiry, the NRC indicated their intent to complete their review and reach a decision by late 1987. -
I t i
I Whereas this schedule appears to be reasonable considering the complexity of the source term issue and the sensitivity of emergency planning issues, BC&E would i
j prefer that the NRC review the application in the context of the plant-specific j
exemption that it is and not to defer it to a longer-term generic effort to revise the present regulations.
4 i
j Meanwhile, at BG&E there exists a keen recognition of the need for a e
thoughtfully designed plan for communicating the essential details of EPZ reduction to i
the media and to the general public . . . when the time is right. This corporate -
communications plan must be implemented through appropriate forums with the objective of providing concise and accurate information to those who need or desire it.
- It is hoped that a skillfully crafted plan will effectively minimize the impact of j misinformation that may come from sources over which BG&E has no control.
.I Before concluding this paper it is important to discuss a subject that has thus far gone without mention; that is, BG&E's goals in pursuing a reduced EPZ. Naturally, 12 1
6 ve .
,--w--r.,,----, , ,-------,_,,-,y-,,-,-...v--.<--v,x v.,--y--,,v-._#...ww..,,v.. . - _ _ , , - _ , ,w.m.--- , #- , . . ~,..-,ym., y-- ---- _.---.y -, ,
'one goal is to simplify and thus reduce the overall cost of the emergency response plan for Calvert Cliffs. Another obvious goal is to make the present plan more effective by concentrating available resources on' the area most likely to be affected by an accident.
Upon closer scrutiny, though, these objectives will seem somewhat transparent in light of the fact that the actual savings attributable to a reduction of the EPZ cannot be shown ,
to be more than modest. Likewise, an equally good argument could be made that, by all accounts, the present emergency plan is effective, and wouldn't necessarily benefit substantially from change. ~
There are three other objectives which can k discerned from BG&E's true Soals and which stem from BC&E's commitment to the continued utilization of safe, clean, reliable and economic nuclear power. These.are:
o To push for NRC recognition of new source term information by applying this new technology in a significant and deliberate regulatory action; o To improve, in the long term, the public perception of the actual risks associated with the operation of Calvert Cliffs, and o To thereby keep the " nuclear option" open in Maryland's energy future.
(
13
_ _ _ . _ _ . _ _ . _ _ _ _ _ _ . _ - _ _ _ _ _ . ._. _ m _ _ _ _ . . _ _ . . ____..__m ___ -. , - . . _ . . .
(, .
i .
1
- 9
- , ce ..
4
! Table.1
]
i COsePARISON OF SURRY. TION. AND Cat.WERT CLIFF 5 Pt. ANT FEATimE5 r i
- Feature h flon Calvert Cleffs i 4
I l. . Power (atut) ,
2440 3250 2700
- 2. N555 centIguratten/supptter 3-loop y 4-loop g 2-loop CE "' [
q 3. Containment free volume (ft') 1.5 x SO* 2.8 x SO' 2.0 x SO' 1 -
- 4. Reinforced or poet-tensioned containment . Reinforced Post-tensioned Post-tensioned 1
S. Containment operating pressure (psta) 90-89 Ato Its
- 6. Containment deelen pressure (pala) 60 52 65 i
- 7. Con.tainment failure pressure (psla) 935 950 140 ,
c O. In-core instrumentation penetration location Sottom Gottom Top
- 0. Cavity condition (etwen spray fatture) . Dry flooded Dry l 10. Concrete type Basaltic Limestone S i t Iceous
i t8. Spray ulthout emergency power No Yes
- No i
1 12. Spray recirc. fr' ;---^r.t of ECCS recirc. Ves No Yes 4
l 1
- 13. ESF containment unit cooters/ filters ,
No Vos Yes j 14. No. of high pressure welwee in ECCS discharge 2 *s. 4 ,
4 u.
j 13. ECCS low pressure line break location submerged Yes Not investigated See Note 5 ,
1 :
$$. SHIl (or shutdown cooling) system inside containment Yes l6s No '
i'
- 37. No. of high pressure valwee in RHR/SCS letdown path N/A - 2 "* 2 "' -
. I
- 83. SHR/5C5 letdown break location submerged N/A No No !
j $3. Cont igpseus structure free volume (f't e ) 30.000 "' t.4 x 90* 2.5 x SO' s Engineered AuxIIlary AuxIIlary
- Safeguards Sullding Building 7 Suilding '
I a (I) Two parallel cold lege per loop.
? (2) CaCOs content compareale to basaltic.
i (3) Including two check walves and NOW in cold leg flow path locked open. .
(4) Including one normally open weighted check valve closing on 300 spe reverse flow. -
! (5) HIgn pressure pump suction outNeerged. Ioes preesure pump discherge not = * ~ god.
- (6) Interlocked to preclude opening ulth high RCS pressure.
j (7) SWI-2804 aseused appeouImata3y 200,000 f a * (apparent 1y inc1udIng quench spcmy pump house and main oteam ve1ve house).
1 1
4 l
.=
TABLE 2 SEVERE ACCIDENT SOURCE TERMS AND PROBABILITY OF OCCURRENCE FOR CCNPP Range of V Sequences I .,
Accident Sequence TMLB'-&e *I TMLB'-SI *I S2 0-Y( LC*(b) High(c)
Probability, Per 7.5 x 10'I 7.5 x 10'I I x 10-7 i x 10- I x 10-7 Reactor Year' (See TABLE 2-6)
Time of Rei, hr. 2.5 2 2.5 > 10I *I 4 Duration of Rel, hr. 10 10 3 1 3 Fission Product Group Fraction of Core Inventory Released to Environment Xe-Kr 0.85 1.00 0.50 t.00 1.00 I-Br 0.07 0.022 0.005 <0.001 0.039 Cs-Rb 0.058 0.013 0.000I <0.001 0.038 Te-Sb 0.055 0.11 0.01 ,' <0.00t 'O.042 Ba-Sr 0.01 0.058 0.03
~
<0.0001 0.0059 Ru 0.0013 0.053 -
0.001 <0.000i <0.000i La 0.0017 0.0002 0.0009 <0.000t . <0.000t (a) kelease fractions from NUREG-0956.
(b) 2 Low range of potential V sequences includes small leakage paths (e.g.,0.1 ft ) at a pump seal submerged in a flood-orotected pump compartment.
(c) High rape of potential V sequences is based on a 14 in. diameter SCS pipe opening - unsubmerged.
(d) 1 x 10~ is the total probability of the ra would be substantially lower than I x 10 .
fge of V sequences for SCS. The probability of experiencing the high range sourc (e) Time of release is a function of postulated size of opening in SCS.
(f) Analyzed in CRAC2 with a 2 hr. release duration. --
+
6
- - - = . _ - - _ - . - - - - ~_ - _
F, s
._OC="
n o .e - - . -
- a ~- - .
s - h a nde< mmh h mmm >ZO ZcmmOa0u40 .
a momyECi< - om mxnmmo Zo uo0 mmg .
s -
51orm GOO < Oomm omm mm>ne0m <m>m .- .
gl1g .
I j/
" s /
=
sE .
~
/
s
/ .
/ 2C=*O.ou8 y-E S p O o.&
.s g
A D a e
- Y a :-
D a 6
0 8
e 4
'E a -
L A, -
O H a 9
W G, ,
R -
MA
+ - e E E - .
R Y 0 R 0 .
2 OT .
C ooM g .
s G A e nn2 m ..
I N E I
R a e. 1 o X D a E R .
E E .
C P
. a s.
X s s
E * .
F a O
Y e AnZ'
- T l . .
A f.1 <.- Q 8
A
=
B O ose g R a e m
P a a
e s.
a M
a .
s . _
s e
s a
o4 - - - - - - - - * . . - _
- g
-O.o Mgo _
- O u.*>Z
- Am 3=.O _
!< f ) i 4' ! ;, :.';<* ]j