ML20245A667

Rebuttal Testimony of G Thompson.* Discusses Environ Contention 3 Re Severe Accident Conditions.W/Certificate of Svc.Related Correspondence

ML20245A667
Person / Time
Site:	Vermont Yankee
Issue date:	06/09/1989
From:	Thompson G NEW ENGLAND COALITION ON NUCLEAR POLLUTION
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ML20245A623	List: ML20245A621 ML20245A667
References
OLA, NUDOCS 8906220112
Download: ML20245A667 (9)

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.. I June 9, 1989 l

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UNITED STATES OF AMERICA-

. NUCLEAR REGULATORY' COMMISSION ' gg MN'14 : PS :07 j

o BEFORE THE ATOMIC. SAFETY'AND LICENSING BOARD

, 4 Jgr F t't,vCi]a ;: ,

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In the Matter-of )

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i Vermont Yankee'Fuclear ) .. .

l Power Corporation ) Docket No.'50-271-OLA

-) (Spent Fuel. Pool)

.(Vermont Yankee Nuclear -) J l Power Station)' )'

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REBUTTAL TESTIMONY-OF GORDON THOMPSON I. Purpose of Testimony i The purpose of this rebuttal testimony is to. respond to a number of factual issues raised in the-briefs and supporting affidavit and testimony filed by the NRC Staff and Vermont Yankee regarding NECNP's Environmental Contention 3, and to address fac-tual questions raised in the Licensing Board's Memorandum of May j 25, 19.89.  ;

II. Benefits of Dry Cask Storage A. Severe-accident Considerations In its Memorandum of May 25, 1989, the Board' asked if NECNP's claim concerning the. environmental superiority of dry-cask storage rests solely on severe-accident' considerations. The' answer to that question is no.- While severe accident risk is a prima 2.y consideration, it is not the only one.

It is important to begin the answer to this question with a preci'se definition of " severe accident." The Severe Accident Policy Statement defines a severe accident as one'in which "sub-

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stantial damage is done to the reactor core whether or not there are serious offsite consequences." 50 Fed. Reg. 32,138 (August 8, 1985). These core melt accidents are also characterized as.

"beyond design basis." Id.

It is possible that a zircaloy cladding fire in the VY spent fuel pool would be accompanied by a core melt accident. However, the proposed spent fuel expansion also poses the risk of acci-dents that do not involve severe core damage, but which could nevertheless involve contamination of the reactor, increased worker exposures and cleanup costs, and serious offsite con-sequences.

In my testimony, I discussed several potential causative mechanisms for loss of cooling water from the spent fuel pool:

core melt accident, an accident during refueling, an earthquake exceeding the SSE of 0.14g, drop of a shipping cask, and l

sabotage.1 Obviously, a core melt accident would be properly classified as a severe accident. However, the other potential l accident initiators would.not necessarily result in core damage.

For instance, a cask drop could lead to a spent fuel pool acci-dent without an accompanying severe core damage event.2 Thus, I dispute the assertion, made at page 11 of the Staff's Environmen-1 See Testimony of Gordon Thompson at 8-9.

2 Note that a cask drop was included under Class 7, " Accidents to Spent Fuel Outside Containment", of the accident classifica-tion scheme established in 1971 under 10 C.F.R. Part 51. Under this classification scheme, it appears that only Class 9 covered what are now described as severe accidents.

tal' Assessment, that'a zircaloy cladding fire is an' event'beyond.

the design basis.

I alsol dispute the Staff's. general assertion that a zircaloy.

cladding fire initiated by a beyond design basis accident is not a " reasonably foreseeable" event. A cladding. fire could be-initiated by several mechanisms, whose probability'is uncertain l

but is. comparable to' probabilities of severe core' accidents which I

have motivated the NRC to alter its regulations incareas such as q emergency planning, hydrogen control, and equipment qualifica-tion.

In summary,. a zircaloy. cladding fire at VY could result from a range of reasonably foreseeable accident initiators encompass-- 1 ing design basis events, beyon'd design basis events, and severe )

accidents. The consequences of a such cladding fire could range from fuel damage, increased worker exposures, and contamination of the reactor building, to catastrophic contamination of a large portion of New England.3 Avoidan'ce of this risk should be a pri-mary consideration in weighing the proposed reracking alternative against the alternative of dry cask storage.

B. Other Benefits of Dry Cask Storage In evaluating the weight of the environmental benefits con-  ;

ferred by dry cask storage, accident risk avoidance is by far the

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3 A fire severe enough to release long-lived radioactivity from the spent fuel pool to the atmosphere could also be-accompanied by a core melt with its own attendant releases. How-ever, it should be noted that a substantial radioactive release from the spent fuel pool could occur without damage to the core.

Egg Testimony of Gordon Thompson at 9.

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most important factor.4 However, dry cask storage also has other environmental advantages. As discussed in the'NRC's recently proposed dry cask storage rule, one of the benefits of dry cask storage is that it decreases reliance on active cooling systems.

In addition, "the potential for corrosion of the fuel cladding and reaction with the fuel is reduced, because an inert atmo-'

sphere is expected to.be maintained inside dry spent fuel storage casks." 54 Fed. Reg. 19,379, 19,380~ Col. 3 (May 5, 1989). HOf .

course, both of these operational advantages have environmental-benefits in that they result in a reduced potential for occupa-tional exposures.

Aside from the relatively uncertain potential under the wet storage alternative for increased occupational exposures due to 1

malfunction of spent fuel cooling systems cnr fuel cladding corro-sion, I agree with Vermont Yankee's experts that over the lifetime of Vermont Yankee, total occupational exposure would be approximately equal for the alternatives of dry _ cask storage and spent fuel reracking.5 Both measures require initial placement'

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of spent fuel in the pool, storage for a number of years, and

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ultimate transfer to casks, either for storage or shipment offsite. If Vermont Yankee implemented the dry cask' option, it would presumably transfer the oldest and most decayed spent fuel 4 I emphasize here that the alternative that I propose -- a combination of dry cask and low-density pool storage -- would completely eliminate the risk of an autocatalytic zirconium reac-

' tion in the spent fuel pool.

5 Egg Testimony of Donald A. Reid, et al., at 13.

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5-to the casks, thereby minimizing occupati~onal. exposures:and maxi-

.mizing the' amount of fuel.that.could be placed:in each cask.. In addition [ the NRC has-encouraged _ cask vendors'to design' casks .<

that.wil1 also be suitable forfshipping, thereby eliminating thel

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need to make an additional transfer 1of the fuel 1for transport purposes. 54EFed. Reg. at 19,382, Col. 1 In-its testimony, Vermont Yankee; lists a number of environ L l mental: costs associated with dry-cask storage, namely the increased use-of steel, concrete, water, and land. None'of these:

environmental costs is s,ignificant. .Moreover, Vermont' Yankee has-not suggested, nor is it evident,'.that the dry cask storage facility could not be constructed within the confines of the Ver-mont Yankee site.

III. Timing of Design and Review In explaining its rejection the dry cask alternative, the .

NRC Staff stated that "there is little likelihood" that design, construction and licensing of a dry cask facility could be com-  ;

pleted in time to meet the need for additional capacity ~ .!

Affidavit of Frederick C. Sturz at 9. Vermont Yankee postulated _

a time frame of between four'and eight years for implementation ~

of the dry cask alternative. Testimony of Donald A. Reid, et 3 al., at 11-12.

I am aware of no fundamental reasons, nor have NRC Staff and VY given any, why the process of designing, licensing, andi installing a dry cask storage facility should take any more time than a year. Unlike many other aspects of nuclear power plant 1 l

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.a design, which typically involve the interaction of complex sys-tems, dry cask storage is a relatively simple technology. More-over,la:s demonstrated by the recent proposed. rule,'the NRC.is now ready to give generic! approval for use of approved cask designs.

54 Fed. Reg. 19,379. Even if that rule were not in place at the time of licensing review, individual review of a. cask design

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should not be very time-consuming, given the fact that the NRC is already familiar with a number of designs. - According.to the NRC Staff's responses of March 14, 1989 to NECNP's First Set of-Interrogatories (p. 12), the NRC has completed.its' review of at least one cask designed specifically.for BWR fuel. The design of a concrete pad and shelter to house and possibly shield the casks j is a simple engineering task which should not be difficult for the NRC to review.

In short, with some sense of urgency and cooperation between the licensee and the NRC Staff, the design and approval of dry cask storage could Jme accomplished in a few months. Construction-of the facility could be accomplished in a few additional months.

Casks could be procured in a phased program extending.over the remainder of the plant's operating life. There is no reason why the implementation of dry cask storage should drag on for years, as forecast by the NRC Staff and VY.

IV. Environmental Impacts of Reracking

! In its Memorandum, the Board asked whether it was required to consider the-impacts of reracking de novo, rather than merely the incremental impacts yet to be experienced. As discussed i

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7-extensively in Section V of my Testimony, the racks themselves .{

have a potential for environmental impact'that'is independent of ]

1 the potential for environmental impacts which arises from the addition of'870 spent fuel assemblies to the pool. Even if VY. f stores'enly 2,000 or fewer assemblies in the pool, the new racks I i

significantly' impede the circulation of air or steam following  :

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i water loss from the pool, thus increasing the risk of a cladding l i

fire. With the addition of 870 assemblies, however, that risk l l

would be exacerbated.

I The Board also asked whether the preferred model of low- 1 I

density racks conforms to the racks at Vermont Yankee immediately {

prior to the current application, or the original racks for 600 l assemblies. While I am not in possession of the design of the I l

original racks or the racks approved in 1977, I believe that the original racks were probably similar to one of the BWR rack designs shown in Exhibits 3 and 4 to my direct testimony. Using these or other racks, it is likely that 600 assemblies can be-accommodated without risk of a cladding fire in the event of total or partial water loss.6 on the other hand, the racks designed to hold 2,000 spent fuel assemblies were probably of a

" closed" design, and probably had essentially the same safety disadvantages as the closed racks described in my testimony.

i 6 Detailed analysis, supplemented by testing, could determine the quantity of spent fuel which could be accommodated, given a particular rack design, without risk of a cladding fire.

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. ;,, g q AFFIRMATION.AND OATH l

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I declare, under penalty of perjury, that the foregoing testimony is true and correct'to'the best;of:my knowledge.. .

G&%.

Gordon Thompson

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1 c,i Signed and sworn to-before me this.I- day of' June, 1989.

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Notary Public [/ '

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I Les C. Haw, Newy P dme .

My Canum E@es Accus 22,1992 1

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9 CERTIFICATE OF SERVICE I certify that on June 13, 1989, copies of the signed and attested Rebuttal Testiony of Gordon Thompson were served by first class mail or overnight mail as indicated, on all parties listed below: _

cocharles Bechhoefer, Chairman Atomic Safety and Licensing Board

• George Young, Esq.

U.S. Nuclear Regulatory Commission Vermont Department of Public Service Washington, D.C. 20555 120 State Street Montpelier, VT 05602

• oGustave A. Linenberger, Jr.

Atomic Safety and Licensing Board ** By hand U.S. Nuclear Regulatory Commission

• By overnight mail Washington, D.C. 20555 ,_,

coDr. James H. Carpenter Atomic Safety and Licensing Board /

U.S. Nuclear Regulatory Commission a Di~ne Curran Washington, D.C. 20555 Secretary of the Commission Attn: Docketing and Service Section ffh oj U.S. Nuclear Regulatory Commission g r, Washington, D.C. 20555 z,2 g

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1 ...s Atomic Safety and Licensing M *- -[ sd I 'M Appeal Board Panel .

~0 U.S. Nuclear Regulatory Commission . ,

Washington, D.C. 20555 [2 I" o

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• oPatricia A. Jehle, Esq.

Office of General Counsel U.S. Nuclear Regulatory Commission Washington, D.C. 20555 George Dana Bisbee, Esq.

Senior Assistant Attorney General Environmental Protection Bureau 25 Capitol Street Concord, NH 03301-6397 OR. K. Gad. III Esq.

Thomas G. Dignan, Jr., Esq.

Ropes & Gray One International Place Boston, MA 02110 George Dean, Esq.

Commonwealth of Massachusetts Department of the Attorney General One Ashburton Place Boston, MA 02108 1

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