ML20235V452

Memorandum of Vermont Yankee Nuclear Power Corp on Existence of Any Genuine & Substantial Question of Fact Re Contention 1.* Facts Established Beyond Any Genuine & Substantial Dispute Demonstrate That Contention Invalid

ML20235V452
Person / Time
Site:	Vermont Yankee
Issue date:	02/28/1989
From:	Gad R ROPES & GRAY, VERMONT YANKEE NUCLEAR POWER CORP.
To:	NRC ATOMIC SAFETY & LICENSING APPEAL PANEL (ASLAP)
Shared Package
ML20235V455	List: ML20235V452 ML20235V478
References
CON-#189-8220 OLA, NUDOCS 8903100194
Download: ML20235V452 (9)

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UNITED STATES OF AMERICA 'g g 3 A939 NUCLEAR REGULATORY COM'MISSION iFT.y #

before the u0Lnt p- <-

vG.V 4ra n tr r ATOMIC SAFETY AND LICENSING BOARD

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In the Matter of )

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VERMONT YANKEE NUCLEAR ) Docket No. 50-271-OLA POWER CORPORATION )

) (Spent Fuel Pool (Vermont Yankee Nuclear ) Expansion)

Power Station) )

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MEMORANDUM OF i VERMONT YANKEE NUCLEAR POWER CORPORATION {

ON THE EXISTENCE OF ANY GENUINE AND SUBSTANTIAL i QUESTION OF FACT REGARDING CONTENTION 1 I SWORN WRITTEN TESTIMONY OF DONALD A REID, JOHN T. HERRON, JAY K. THAYER, CHRISTOPHER H. HANSEN, AND PAUL A. BERGERON, SUBMITTED BY VERMONT YANKEE NUCLEAR POWER CORPORATION PURSUANT TO 10 C.F.R. g 2.1113(A) .

J John A. Ritsher R. K. Gad III Ropes & Gray One International Place Boston, Massachusetts 02110 Telephone: 617-951-7000 February 28,1989.

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UNITED STATES OF Ah1 ERICA NUCLEAR REGULATORY COSINilSSION before the ATOhlIC SAFETY AND LICENSING BOARD

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In the Matter of )

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VERMONT YANKEE NUCLEAR ) Docket No. 50-271-OLA POWER CORPORATION )

) (Spent Fuel Pool (Vermont Yankee Nuclear ) Expansion)

Power Station) )

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51Eh10RANDU51 OF VERhf0NT YANKEE NUCLEAR POWER CORPORATION ON THE EXISTENCE OF ANY GENUINE AND SUBSTANTIAL QUESTION OF FACT REGARDING CONTENTION 1 Pursuant to 10 C.F.R. Q 2.lll3(a) and the Memorandum and Order of this Board dated January 10, 1989, the Licensee in this matter, Vermont Yankee Nuclear Power Corporation (" Vermont Yankee"), submits this memo-randum containing what it believes to be all the relevant facts, data and argument on the validity of Contention 1. Vermont Yankee contends that Contention I is incorrect and should be dismissed on the merits.

I. THE NATURE OF TIIE PROCEEDINGS, A. The Proposed Amendment.

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Vermont Yankee Nuclear Power Station ("VYNPS") is a boiling water I

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reactor located in Vernon, Vermont. When originally licensed in 1972, the )

VYNPS spent fuel pool had a capacity of 600 spent futi assemblies. Li 1977, the capacity of the VYNPS spent fuel pool was expanded to 2,000 spent fuel assemblics. Verment Yankee Nuclear Pcwer Corporation (Vermont Yankee Nuclear Power Station, ALAB-455, 7 NRC 41 (1978), aff'd in relevant part sub nom. Minnesota v. NRC, 602 F.2d 412 (D.C. Cir.1979). In April of 1986, Vermont Yankee submitted to the NRC Staff an application for an operating

license amendment to increase the maximum authorized spent fuel storage capacity to 2,870 spent fuel assemblies. This proposed expansion, as the previous one, will be effected by the substitution of new racks that would permit the storage of a greater number of spent fuel assemblies in the same spent fuel pool. As originally proposed, only the design of the racks would have changed; in all other respects the VYNPS spent fuel pool and associated systems would have remained identical.

In May,1987, this Board admitted Contention 1, which challenges the adequacy of the heat removal capacity of the existing VYNPS spent fuel pool cooling system, given the supposedly higher heat loads to be imposed upon the pool by the expansion.1 In an effort to moot the contention, the Licensee committed to the NRC Staff that, prior to any reliance upon the authority to exceed the existing 2,000 spent fuel assembly limit, it would install an additional spent fuel pool cooling sub-system, which provides for two additional cooling trains of even larger capacity than is available given the existing system. It was, and remains, the position of Vermont Yankee that this spent fuel pool cooling system enhancement is not necessary to defeat Contention 1, that is to say, that the contention is invalid whether or not the enhancement is installed.

B. The Contention.

The admitted contention reads as follows:

"The spent fuel pool expansion amendment should be denied because, through the necessity to use one train of the reactor's residual heat removal system (RHR) in addition to the spent fuel cooling system in order to maintain the pool water within the

[ design] limits of [150*FJ, the Single-failure criterion as set forth in the General Design Criteria, and particularly Criterion 44, will be violated. The Applicant has not established that its proposed method of spent fuel pool cooling ensures that both the fuel pool cooling system and the reactor cooling system are single-failure proof."

i I i Siace the bulk of the peak heat load ever imposed upon a spent fuel pool comes from the recently discharged assemblies, and since the effect of a pool expansion is to increase the number of old assemblics in the pool, the supoosed increase in heat ioads is, in reality, quite small. See Licensee's Direct Testimony. Exhibit f. A 44% increase in spent f uel pool inventory l produces only a 12% increase in heat load.

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Vermont Yankee Nuclear Power Corporation (Vermont Yankee Nuclear Power Station), ALAB-869, 26 NRC 13, 20, 23 (1987). The " basis" for the conten-tion was succinctly stated thus:

"Should this amendment be approved, it would be necessary under certain conditions to use one train of the reactor's residual heat removal system (RHR) in addition to the spent fuel pool cooling system in order to maintain the pool water within the design limits of 150"F. . . . The heat load in the pool after a normal fuel discharge is roughly 50% greater than the design capacity of both trains of the spent fuel (r001] cooling system.

While Applicants assert that the two pumps in one RHR train are single active failure proof, they have not demonstrated that there is no single failure in the RHR system components and power supplies that would not disable the single train of RHR.

"Moreover, under conditions where one RHR train is needed for spent fuel pool cooling, there is only one train available for decay heat removal from the core. Applicants have not estab-lished that this leaves a single failure proof method of cooling the core.

"In summary, Applicants have not established that their proposed method of spent fuel pool cooling ensures that both the fuel pool cooling system and the reactor cooling system are single failure proof.as The contention was apparently borne of some (i) misunderstanding about the heat removal capacity of the existing VYNPS spent fuel pool cooling system and the loads imposed upon that system 8 and (ii) misunderstanding about a design feature that VYNPS has always had that permits one train of '

s"New England Coalition on Nuclear Pollution's Response to Board Order of February 27, 1987: Statement of Contentions and Standing" (March 30,1987) at 6-7.

8 Thus, for instance, the assertion that "[T]he heat load in the pool j after a normal fuel discharge is roughly 50% greater than the design capacity of both trcins of the spent fue! [ pool] cooling system," appears to have been {

based upon the pleader's use of FSAR figures for the heat removal capacity of the existing spent fuel pool cooling system without accounting for the difference between the reference inlet temperatures used in the FSAR and the temperatures at which the cooling system reaches its capacity. From the l

data contained in Licensee's Direct 7'estimony one can determine that the I correct values are 9.1 MBtu/hr. (at 10 days, using extremely conservative assumptions) for the beat load imposed upon the pool after the last norma' refueling that fills the pool to 2,870 spent fuel assemblies, while the cooling I capacity of the existing spent fuel pool cooling system (both trains operat-ing) is 15.5 MBtu/hr. This means that cooling capacity exceeds heat load (by about 2b%), not the revert,e.

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) the RHR system to be aligned to the spent fuel pool if desired. The

. proponents of the contention apparently believed that resort to the RHR to f- cure an inadequacy of spent fuel pool cooling was a regular event, and that the added heat loads of the increased spent fuel pool inventory would aggravate that situation.

As is demonstrated as a matter of technical as well as historical fact, however, that fear is not (and never has been) well taken. The VYNPS spent fuel pool cooling system, in its existing configura-

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tion and even after degradation by the most critical single active failure, has adequate heat removal capacity to take the heat loads imposed by a normal f refueling discharge both with 2,000 spent fuel assemblies and with 2,870 spent fuel assemblies in the pool. Moreover, the proposed enhancement to the spent fuel pool cooling system adds even more cooling capacity.

Thus, in the words of the contention, there is not, never has been, and

, never will be, any " necessity to use one train of the reactor's residual heat removal system (RHR) in addition to the spent fuel cooling system in order 8

to maintain the pool water within the [ design] limits of (150*F]."

II. The Facts.

The facts upon which Vermont Yankee relies are set forth in the

" Sworn Written Testimony of Donald A. Reid, John T. Herron, Jay K. Thayer, Christopher Hansen and Paul A. Bergeron, Submitted by Vermont Yankee Nuclear Power Corporation Pursuant to 10 C.F.R. Q 2.1113(a)," submitted herewith.4 This testimony establishes the following propositions of fact, which the Board should find:

A. IIeat Loads. The most critical heat loads imposed upon the spent fuel pool cooling system are those that result from 1/3 core (normal) refueling. While the freshly discharged spent fue! assemblies have a high level of decay heat (compared to the balance of the pect inventory), the readiness of the reactor for restart requires thr.t the spent fuel pool be i

severed from the reactor fluid system, whose RHR has been cooling the l 1

combined fluid system during refueling. Licensee's Direct Testimony at 6. '

The magnitude of this heat load depends upon the interval between when the nuclear reaction was shut down and when the, reactor is ready for )

4 This document is hereinafter referred to as " Licensee's Direct Testimony."

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restart. Licensee's Direct Testimony at 14. The historical average refueling outage duration at VYNPS has been 44 days, and the most rapid normal refueling still took 25 days.3 Licensee's Direct Testimony at 14. As one element of conservatism,8 the heat loads are calculated as if all of this were performed in 10 days. Id. At the 10-day point, the heat load on the spent fuel pool is 8.12 million Btus per hour ("MDtu/hr.") given a pool containing 2,000 spent fuel assemblies, and 9.1 MBtu/hr. given a pool containing 2,870 spent fuel assemblies. Licensee's Direct Testimony at i1.

Any cooling system with a capacity equal to or greater than the heat load on the pool will cause the water in the spent fuel pool to maintain temperature or decline in temperature.7 While greater heat loads are imposed upon the pool by full-core discharges, the spent fuel pool cooling system need not be relied upon to provide spent fuel pool cooling in such a case. Licensee's Direct Testimony at 6.s 3

Outages that involved fuel movements of fewer than a normal refueling have taken, at the minimum,18-21 days. Of course, the heat loads imposed upon the spent fuel pool cooling system by restart following these " fuel movement" outages have been even less than those imposed by a normal I refueling.

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6 i As is set forth in the Licensee's Direct Testimony, a number of I conservative assumptions are made in order to exaggerate the heat load l

imposed on the cooling system. These include assuming an extremely rapid  !

refueling (more than twice as quickly as has been historically achievable), a l conservatively long fuel cycle, a higher power level than the reactor is licensed for and an impossibly high cumulative capacity factor. Licensee's Direct Testimony at 9-10.

7 The temperature of the water in the pool is determined by the algebraic sum of the heat added to the water less the heat rejected from the water to some other medium. Although (for conservatism) no credit is taken for it, some heat is always rejected to the atmosphere through evaporation.

Therefore, if the heat load imposed by the spent fuel and the heat removal capacity of the spent fuel pool cooling system were exactly equal, the bulk l water temperature in the pool would decline.

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8 1n addition, as demonstrated by the words of the contention and the words of its associated basis, the contention is (properly) limited to the effect of normal,1/3 of tht core refueling, followed by restart.

h B. The Heat Removal Capacity Atallable. I

1. The Existing Cooling System. The existing VYNPS spent fuel pool cooling system consists of two pumps and two heat exchangers. Licen- l see's Direct Testimony at 7. The heat exchangers are configured such that l

J either can be aligned to either of the pumps, resulting in three possible 'l configurations of the system. Licensce's Direct Testimony at 7 As the heat I

I exchangers are passive components (while the pumps are active components),

the most critical single active failure results in a one pump - two heat exchangers configuration. Licensee's Direct Testimony at 7 In this  !

configuration, the heat removal capacity of the existing spent fuel pool l cooling system is 9.1 MBtu/hr. Licensee's Direct Testimony at 8-9.8

2. The Enhanced Cooling Sub-System. The enhancement to the j

spent fuel pool cooling system proposed by Vermont Yankee adds to the existing system a two-loop standby sub-system. Licensee's Direct Testimony f

at 15-17 Each of these'two loops is entirely redundant and each has a heat i I

removal capacity of 11.0 MBru/hr.18 Licensee's Direct Testimony at 16.

j Thus, the heat removal capacity of the spent fuel pool cooling system, with the enhancement, is substantially increased.

C. Use of the RHR System for Spent Fuel Pool Cooling Enhancement.  !

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As noted above, Contention I seems to have been borne of the misimpression f

that resort to the RHR for augmented spent fuel pool cooling on account of 8

While the spent fuel pool water temperature is normally held at a lower value, the licensing condition applicable to VYNPS specifies a limit of q 150*F. Licensee's Direct Testimony at 9. All other things equal, the heat removal capacity of a heat exchanger increases as the temperature of the water being cooled increases. Licensee's Direct Testimony at 8. Thus, as the temperature of the water in the pool increases, the heat removal capa-city of the existing spent fuel pool cooling system in any of its configura-tions increases. As the design capacity of the existing system as stated in  !

the VYNPS FSAR is for references temperatures, the failure to account for the ternperatures at which the cooling system reaches its capacity will  !

erroneously lead one to underestimate the capacity of the system. Licensee's l Direct Testimony at 8. j

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loLike the existing system, the enhanced sub-system is constructed so i 1

that it can operate in a one pump-two heat exchanger mode. While the cooling capacity of the system in this mode has not yet been determined with precision, it will be less than 22 MBtu/hr. but significantly more than I1 MBtu/hr. Licensee's Direct Testimony at 16.

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spent fuel pool cooling inadequacy is a common occurrence at VYNPS. The data set above demonstrates that there will not be any need for resort to

[ the RHR system to compensate for a spent fuel pool cooling system heat removal insufficiency -- with or without implementation of the emergency sub-system. In addition,16 years of operating history reveals that, in fact (and as would be expected), such resort has never been made. Licensee's j Direct Testimony at 6, l5.

I D. Compliance with the Single Fallure Criterion. As the foregoing i

Y data reflects, the existing spent fuel pool cooling system has the capacity to remove enough heat load to keep the pool water at or below 150'F after 10 days of decay following shutdown of the nuclear reaction. Licensee's Direct I

Testimony at 15,17. (In fact, during the time the proposed amendment is in force, the time required to reach the point at which the spent fuel pool load I

can be carried by the single-failure configuration of the existing spent fuel pool cooling system ranges from 6-7 days to 10 .!I days. Licensee's Direct Testimony at 15.) Since it is not necessary for the spent fuel pool cooling system to perform this task until the reactor is ready to restart," and since readiness to restart cannot occur until almost twice this 10 day period, it therefore follows that the situation of spent fuel pool cooling system I

inadequacy hypothesized in the contention cannot occur. Licensee's Direct Testimony at 17. From this it follows that the contention is without merit an'd must be dismissed.

The scenario on which the contention posits a violation of the single failure criterion cannot happen for another, independent reason. As stated  !

in the Contention, the theory of the Contention is that, on account of a  !

v heat removal capacity inadequacy, resort to the RHR to cool the independent spent fuel pool must be made. Either the necessity of such resort renders the spent fuel pool non-compliant with the single failure criterion (so the Contention goes) or the use of the RHR for this purpose (leaving only one train of RHR on the reactor) leaves the reactor non-compliant with tne single failure criterion. However, the VYNPS Technical Specifications "During refueling, both RHR system trains are availatle to cool the sper.t fuel pool and the reactor, as a single fluid system. Licensee's Direct f Testimony at 5. i l

1 require that both trains of the RHR be available for the reactor in' order to restart the reactor. Licensee's Direct Testimony at 6. Thus, even were the contended-for scenario to occur (which the data says won't happen and which history demonstrates has never happened), the reactor cannot be I

restartad.18 f  ;

Conclusion I 1

For the foregoing reasons, the facts established beyond any genuine and l

substantial dispute demonstrate that Contention 1 is invalid and should be l, dismissed. i i

ully submitted,

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John A. Ritsher R. K. Gad III

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Ropes & Gray One International Place Boston, Massachusetts 02110 Telephone: 617-951-7000 February 28, 1989.

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12 Even more distended is the notion that the heat removal capacity Ij deficiency in the spent fuel pool first develops after the reactor has been started. This would appear to be impossible, since the only way to increase the heat load on the pool is to off-load teeut fuel assemblies into the pool.

Once the reactor h.is been started, the progression of spent fuel assembly-generated heat in the pool is alwayt decret. sing.

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