ML19338F295

Decision Granting Variance from Interim Acceptance Criteria, Extending Date for Compliance Until 760901, & Extending Until 750404 Deadline for Submittal of Evaluations for ECCS

ML19338F295
Person / Time
Site:	Dresden
Issue date:	08/05/1974
From:	Muntzing L US ATOMIC ENERGY COMMISSION (AEC)
To:
Shared Package
ML19338F294	List: ML19338F293 ML19338F295
References
NUDOCS 8010170669
Download: ML19338F295 (12)

Text

_

UNITED STATES OF AMERICA

)h :

ATOMIC ENERGY CCHMISSION rE iii:i: ~

i.![.

In the Matter of COMMONWEALTH EDISON COMPANY Docket No. 50-10

=

(Dresden Nuclear Power Station Unit 1) v.

DETERMINATION WITH RESPECT TO VARIANCE FROM THE INTERIM ACCEPTANCE CRITERIA AND EXTENSION IN SUBMITTING EVALUATIONS

'Z FROM THE ACCEPTANCE CRITERIA FOR EMERGENCY

~.

CORE COOLING SYSTEM [10 CFR 1 50.46(a)(2)(iii)]

By letter dated June 10, 1974, the Comonwealth Edison Company (licensee) requested a variance for the Dresden Nuclear Power Station Unit i reactor from the requirement for achieving compliance with the Conhission's Interim Acceptance Criteria (IAC) for Emergency Core Cooling Systess (ECCS) for Light-Water Power Reactors set forth in the Comission's Interim Policy Statement by July 1, 1974 (36 F.R. 12247, June 29, 1971).

The variance requested was for an extension of time until January 1,1976, f

to meet the requirements of the IAC. On July 19, 1974, the 11 cense 2

.]

supplemented its request for variance from the IAC by requesting the period

[

of variance be extended from January 1,1976, to September 1,1976.

On June 14,1974, the Director of Regulation published (39 F.R. 20834) a notice of the receipt of the licensee's request for a variance. This g;.

notice advised tnat the Director cf Regulation was considering granting a variance from the IAC. This notice also invited the submission of views i

and comments by any interested persons. t;o coments were received. On

~ #:' ::4..........

Og

=

=

~

l mitw+

i..

==

-y_

s==.

==.:.= =E 7.f'.f.*.. I.

In consideration of (1) the extremely low probability of a LOCA occurring L.l]

simultaneously with a loss of all offsite power and (2) the cppability of E.={

primary coolant leak detection and inservice surveillance to discover leaks or potential leaks before cracks can propogate appreciably, the staff has g

concluded that there is reasonable assurance that granting such variance

"==j will not adversely affect the health and safety of the public. We have con-s; sidered and determined that a variance from the IAC for the full period requested.

..]i until September 1,1976, would be accaptable,-provided that the licensee a:

=g makes additional modifications by September 1,1976, to reduce the vulnerability

=

of the Dresden Unit 1 ECCS to failure of a single onsite power source and continues inservice inspection at triple the frequency required by Technical Specifications. However, the licensee is also subject to the requirements

=

of the Connission's revised acceptance criteria set"forth in 10 CFR 50.46.

As a result of the licensee's request for an extension of time to file an M

evaluation of ECCS performance in accordance with'10 CFR 50'.46, the licensee U

l will be required to file a preliminary evaluatio of performance with the revised acceptance criteria by October 31, 1974. See discussion below.

At that time the licensee may request an exemption from the Connission from j

{

the operating requirements of 10 CFR 50.46. Accordingly, this variance extends.only until operation in conformity with the acceptance criteria of 10 CFR 50.46 is required, unless an exemption from such requirements 1J grantdd j

by the Connission.

In addition, this variance is subject to a requirement that the licensea report periodicelly, het net less trien ence every tiree mantt.s I

coNnclig"WiiE"f6E"ddE5"5Hhisdetermfiaifoi~to the DffeEE i"i d egulatii on SURNAME >

T

.:a..

.. :.4..

g..

=

Q C

+ +.

=A

_g.

ii#ig June 28, 1974, the Director of Regulation issued a detemination (39 F.R.

9.h

=

24942) extending the July 1,1974, date for compliance with the IAC to i

= E=i August 5, 1974. The purpose of this extension of time was to pemit J~

consideration by the Regulatory staff of all requests submitted by other

== 9 licensees subject to the provisions of the IAC and 10 CFR I 50.46 for variances or extensions of time from the provisions of the IAC or 10 CFR

=

5 50.46 to assure uniform and consistent treatmen* of all ECCS evaluations.

f The interim detemination stated that a final determination would be made

=;;.

by August 5,1974, as to whether a further variance should be granted.

[

By letter of June 20,1974 the licensee also requested an extension

~

s of time until May 5,1975 for submission of an evaluation of ECCS

~

performance in accordance with 10 CFR I 50.46. As required by in CFR subsection 50.46(a)(2)(iii), a Notice was published in the Federal Register on July ll, 1974, (39 F.R. 25527) that the Director of Regulation N

had received and was considering a request from the Comonwealth Edison Company (the licensee) for an extension of time until May 5,1975, of the submittal date for the Dresden Station, Unit 1 (Dresden 1) ECCS evaluation.

The Notice also invited the submission of views and coments by any interested persons on the licensee's request. Coments have been

==1 i

q received from Friends of the Earth and Consolidated National Intervenors.

' *: j These groups oppose the granting of the requested extension of time on

.]

the grounds that the licensee's application does not present evide,1ce to demonstrate why the vendor's analyses are delayed and that the licensee should not be pemitted an extension of tima ta 1 anua=+ an eye ptfem

[

off tCE >

~

. ~ - -. -

~~~"

' " ~ ~

~

" " " " " ' " " " " * * " ~ ~

^

$URNAME > 3.-

==hhi.

'nixi-ii=rurun.

...~.7

....:..ls..\\..:i

.-..L.

'::y::".~T::.' ' 23

(

+

=

r.

5.55 VARIANCE FROM INTERIM CRITERIA f.h=:

By letter of May 1,1972, the licensee submitted a report analyzing 5E the conformance of Dresden 1 to the IAC. The rsport indicated that by use of an engineered safety system (the core spray system), installed after publication of the IAC and systems which are not specifically designed as engineered safety systems (emergency condenser and the primary feedwater system) the fuel clad temperatures and metal water reactions would remain below the limits specified in the IAC for any size primary system pipe break

==

at any location. Cooling for small and intennediate breaks would be provided by the primary feedwater system. Cooling for large breaks, including a double ended rupture of the largest pipe below core level would be provided by the

==.

core spray system.

In February 1973 the licensee submitted additional analyses based on the use of the same systems and accounting for the effects of fuel densification which again indicated that the IAC limits had been met. The Regulatory staff evaluated the analyses and in a letter to the licensee dated February 22, 1974, it concluded that even with densification E=

effects, Core IX (the present core) meets the IAC limit of peak fuel clad temperature of less than 2300*F. Analyses submitted by the licensee also indicated that for a spectrum of large break sizes below the core, including the double ended break of the largest line, the IAC limits could be met without reliance on the feedwater system or offsite power. Therefore, in f"

the event of a loss-of-coolant accident (LOCA), it is highly Onlikely t60 the

=;

IAC limit for fuel clad temperature and metal water reaction would not be achievet.

OfF1CE >

SURNAh6E >

d

.. =.

=n

==

. :=

.: =..

,s G

s =.

=q The requirement that the core temperature be reduced and decay heat E

be removed for an extended period of ' time, as required by the long-lived

==

radioactivity remaining in the core, is fulfilled by the existing core spray system operated in a mode which recirculates water within the containment building and powered by either onsite or offsite power.

Although systems are available which can maintain fuel clad

m. se ea temperatures below 2300*F after a LOCA, the redundancy and level of reliability of installed systems should be improved in consideration of e-ii. -

w-long-tem operation, i.e., the system can be substantially reduced in effectiveness by a single failure independent of and coincident with a LOCA. The feedwater system would not be operable for small and l

intemediate sjze primary system pipe breaks if offsite power were lost coincident with a LOCA. Also the controls for the feedwater system were not specifically designed to meet single failure criteria and have not been s

1 evaluated for. their vulnerability to single failure. The low pressure core

=;

/

spray / system would not be available for large size primary system breaks if a

+;

the LOCA were accompanied by loss of all offsite power and a loss of the

]

l sing 1'e onsite emergency diesel generator.

Because the design of the present ECCS does not meet the IAC. the j

licensee has committed to installfDg a high pressure coolant injection systen by September 1976 which would supersede the feedwater system and

==i5 l

emergency condenser and would eliminate the need for offsite power for motive power for the high pressure pumps. Since the system as proposed l{.:

r m !d etn1 w eepena nt en tw eing!e enett-die: ! generatcr and :teg1:

p f

omer >

wru:

su=r i,

=== :===:

m.:.m.

7 s

O

.=

,5-battery system, the licensee will be required to make additional modifications to remove the vulnerability to failure of single onsite power sources.

In Y

discussions with the licensee, the Regulatory staff has been infomed that the requirement for another diesel generator and battery system would not prolong the schedule for completion of aa upgraded ECCS.

Since publication of the IAC, the licensee has taken steps to decrease the probability of occurrence of primary system pipe cracks and large coolant leaks.

By letters dated Nove.uber 11,1971, and December 29,' 1971, the s=

licensee proposed an augmented reactor coolant system pressure bouddary

.=2 inservice inspection program in accordance with Section IV.c l.b.(3) of the

~~

IAC.

In a letter of February 2.1972, the Regulatory staff approved the program as ' fulfilling the inservice inspection requirements of the IAC.

In l:E response to proposed program revisions from the licensee dated January 25 M

and May 17. 1973, the Regulatory staff again evaluated the inservice inspection program'and approved the tvtised orogram by letter of September 17, 1973.

The Dresden Unit I reacter is equipped with highly sensitive leak

.=

deteckton!,ystems. Two of the systems, a continuous containment air mont r and a continuous stack air monitor are capable of detecting leaks well under one gpm.

In addition, a containment compartment sampling system is ayailable which is less sensitiva than the continuous air monitors but 1

n.p which has capability for leak detection and is an aid in locating a leak, y

By amendment dated July 29, 1974, the Regulatory staff issue 2 Technical

" s3 0

Specifications which require that on detection of a radiation level increase g )u ap;@t ta a aat sta or aLon 0.m,, so,6 ;u;uned 6 ciumr e

isolate the leak or shut down the reactor........

Y omez w F

i su m p 49.g..p.

g....q g.

i

..._4

'Jf

. [..)

The Drtisden Unit 1 reactor is one of the earliest boiling water reactor designs. As a consequence, an ECCS evaluation model and accompanying

==

m ECCS perfomance analysis had to be developed by the licensee and its contractors taking into account the specific Dresden Unit 1 reactor design.

This has and continues to involve significant amounts of time in order to perform and evaluate the various computations. The Iicensee has informed us that additional delays were encountered in obtaining enough infomation to estimate design requirenents of the HPCI. As a result of these delays

=[:

in obtaining the required information and analyses to design the system, the licensee was only recently able to request bids for equipment with long y:

lead time. Additional time is now required by the licensee for awarding

=

"~

contracts, fabrication, delivery, erection, and testing.

~

The Regulatory staff met with the licensee representatives on.

July 18,1974 to review the licensee's schedule for completion of the modifications. The staff examined the various equipment delivery and

=-

installation schedules presented at the meeting and in the ifcensee's letter of July 19,1974 and in light of the staff's knowledge of the y

general installation requirements and procurement situation for nuclear y

l reactor grade equipment it is satisfied that the proposed schedule for f

having all proposed additional components installed and operable by September 1,1976, represents a reasonable, minimum time to completa H

the major nodifications which are planned and required. The staff has detemined that good cause exists for autherfration of the requested varianedfromtherequirementsoftheIAC.

[?

omcc>

^,

j h

rf

'f,4

$URNAME> l.....

I

=

== =

== L 2 y, i~ii:5:t

g..

In consideration of (1) the extremely low probability of a LOCA occurring mrd =... ~ simultaneously with a loss of all offsite power and (2) the cppability of J"i primary coolant leak detection and inservice surveillance to discover leaks or pohntial leaks before cracks can propogate appreciably, the staff has concluded that there is masonable assurance that granting such variance M will not adversely affect the health and safety of the public. We have con- [.[.; - sidered and determined that a variance from the IAC for the full period requested. i=:i - until September 1,1976, would be acceptable, provided that the licensee

== makes additional modifications by September 1,1976, to' reduce the vulnerchility of the Dresden Unit 1 ECCS to failure of a ' single onsite power source and continues inservice inspection at triple the frequency required by Technical Specifications. However, the Itcensee is also subject to the reqifrements of the Connission's revised acceptance criteiia set"forth in 10 CFR 50.46. ~ As a result of the licensee's request for an extension of time to file an evaluation of ECCS performance in accordance with 10 CFR 50.46, the licensee

==l ~ will be required to file a preliminary evaluation'of performance with the revised acceptance criteria by October 31, 1974. See discussion below. 1 At that time the licensee may request an exemption f rom the Connission from _y the operating requirements of 10 CFR 50.46. Accordingly, this variance f ......i H extends only until operation in confamity with the acceptance criteria of 10 CFR 50.46 is requimd, unless an exemption from such requirements is grantdd

)

:.j by the Connission.

[j In addition, this variance is subject to a requirement that the

• 1

.I licaraan report parisdim...,, y _.~.~..m.. ...,.. m.,~..- ...........................l.................. omer > --.--m......... connencing with the date of this detemination..to the Directc r of Regulation $URNAME> ..:m:

m

== e=== n= -

= *

== == .,... +,.. =. G.- r? '- =. its efforts in attempting to achieve compliance with the IAC. Should these reports reveal that the licensee is not pursuing such compliance in a reasonably diligent manner, the variance may be subject to revocation. Extension of Time for Submission of Evaluation in Conformity with i 50.46 7-In support of its request for an extension of time, the licensee states that it does not expect to receive the ECCS evaluation model and analyses from the General Electric Company (GE) for Dresden Unit 1 before Man:h 1

=e._

1975. The licensee states that the requested extension will allow approximately { one month to review the results of the analyses and develop approprgate Technical Specifications changes. The basis for the remaining time of the requested .== l extension was to allow time for filing a request for exemption in the event .? that became appropriate. It is evident from the licensee's request that the basis for an extension of time is the unavailability of the necessary evaluation models .,q and analyses from GE. Since the promulgation of the regulation, the e Regulatory staff has been engaged in a continuing effort to develop an q n AEC evaluation model which would meet the requirements of Appendix K d.. of 10 CFR Part 50. A similar effort has been underway by the four I vendors of touclear steam supply systems for light-water nuclear power reactors, including GE. As the Regulatory staff recognizes from its efforts, this development work has involved a considerable amount of time. =: Furthermore, the Dresden 1 reactor is an older design which req $tres significant changes in the evaluation models now being calculated for most 1 i of GE's newer datione. nr muet th.c. h n n= ~. ..n.--+. ....i...*4-modM%I" analysis Whi h~Ts~ tait 6 Fed t5 hiIDiEidin"1 Eift h Il $ URN 4WE> IM

u=%.-:g: 5= N=

==

.;=== t

==

=

+= =%= :- - ~ (... (. s involve additional titre beyond the time estimated for submission of the evaluation nedels for the newer designs. }.{.{ Based upon the Regulatory staff's experience and its knowledge of the efforts on the part of GE to develop adequate evaluation models and analyses, the Regulatory staff believes that the licensee's statements regarding delay by GE in completing and submitting to it nn evaluation model and analyses constitute good cause for extension of the August 5,1974, deadline for the .,= submittal of the infomation required by 10 CFR Section 50.46. The Regulatory staff, however, does not believe the licensee has justi- = fied in its submittal the length of time requested. The Regulatory staff has independently developed a schedule of the steps and average times that should be sufficient for internal review by the licensee after trans'nittal by.GE of the GE evaluation and analyses to the licensee, This schedule takes into account the review schedules submitted by all licensees who have requested extensions as well as the Regulatory staff's own views as to the mini:mrn time which should be required for the licensees to conduct the necessary reviews and to prepare the necessary information t. for submittal to the Regulatory staff. The Regulatory staff's schedule is as follows: 1. Engineerirg review (including 0/A review) of evaluation [: rodels and analyses. (7 days) hy 2. Preparation of proposed Technical Specificatinas and revised ~ operating procedures. (14 days) 3. Revieu by clant operations and nuclear safety comittee ani E omes >. appropriate pany nuclea -review-comittee;----{10 d ys-)- sunmc w - j=

3.g.:: ..= .=

(.h f2=

E - 25 4. Submit. (4 days) i3 = Total Time: 35 days. {:j Based upon the above, the Regulatory staff has concluded that an extension E of time of 35 days should be granted to the licensee commencing with the date g g of transmittal by GE of the GE model and analyses to the licensee. [.g The Regulatory staff has taken the comments of Friends of the Earth 5 .:=1 ?j and Consolidated National Intervenors into account in reaching its E: determination reflected herein. In this regard, the Regulatory staff ]) believes that, as noted above, the licensee has shown good cause for the 55 .d d granting of an extension of time. The Regulatory staff did not consider ~ in its determination of good gause the need for additional t'ime in which j

=

"j to file an exemption request. j .H,owever, while there may be good cause for the licensee's inability = -J t.... j .to supply a complete evaluation of ECCS performance in accordance with F '2 section 50.46, including all required and. acceptable elements and documentation in;accordance with Appendix K, until April 4,1975, the Regulatory staff h V: believes thatspreliminary evaluation, based on conservative assumptions, but [.; !? not necessarily including all of the detail and documentation called for by !? Appendix K, but which nevertheless provies a conservative assessment of ECCS ik. performance under the Commission's Acceptance Criteria, should be provided a by October 31, 1974. The staff recognizes that simplifying, but conservative, ?$ E.g assumptions must be made in order to provide the evaluation by October 31, [ g 1974, but the submittal must present details of such assumptions and estimates and supporting discussion to demonstrate that the preliminary evaluation meets g

h

^ .y.:. =: - .g

==' =PnE gd::

=:

5:h = ^"' h:k. : ~=::-

=~ g=:==e+i adM==== +EH -..e. .m -. z;. '...::;. s.... :..:=......... ^ h::L:

=:- "

== ~'" ~ ~ ([ =,u 11 - r::: =6 1.!!.: i:d= the Comission's acceptance criteria, and include proposed. operation limits, i=Ei if any, required to bring the reactor into conformity with the Comission's 173 y acceptance criteria. Upon receipt of the final evaluation model and analysis l.l.y from t% vendor, the licensee shall submit this evaluation model and analysis for concurrent review by the Regulatory staff. ACCORDINGLY, based on the foregoing considerations, the Director of ji Regulation has granted a variance for the Dresden Nuclear Power Station = Unit 1 which extends the date for compliance with the requirements of the. = =. Interim Acceptance Criteria until September 1,1976, provided (1) the. licensee shall report periodically, but not less than once every chree months commencing with the date of this determination to the Director of Regulation its efforts in attempting to achieve compliance with the IAC. Should these reports reveal that the licensee is not pursuing such compliance [ in a reasonably diligent manner, the variance may be subject to revocation. (2) this variance extends only until operation conformity with the acceptance criteria of 10 CFR 50.46 is required. If an exemption from such requirements - =... is granted by the Commission, such exemption shall govern any further ~ 3 = j operation of the facility. In addition, based on the considerations set forth above and for good ) S cause shown, the Director of Regulation hereby grants an extension of time k to the licensee which extends the date for ' compliance with the requirements _= of 10 CFR subsection 50.46(a)(2)(ii) from August 5,1974, until April 4, 1975, rovided that (1) upon receipt of the final evaluation model and p analhis from the vendor, the licensee shall submit this evaluatinn mndel '::::. 0., ....-.....I.. .l.. l w

.:v.

~

.v

5.b::.

?

~= =?

.E:

:

= =

. -., i

i t.; = = :=.: .."'i

==: and analysis for concurrent review by the Regulatory staff and (2) on or before October 31, 1974, the license.e shall submit a preliminary evaluation of ECCS performance consistent with the requirements of Appendix X although = = not necessarily containing the full detail and the full documentation called for in Appendix K, along with proposed license amendment or Technical Speci-fication changes which would bring reactor cperation into conformity with the ~ requirements of section 50.46. Upon submiss!or., the licensee shall operate within the limits of such proposed technical s,wcification and all technical specifications previously imposed by the Commission, including the require-ments of the Interim Policy Statement (36 F.R.12247, as amended by 36 F.R. 24082 December 18, 1971), or any variance granted from such requirements unless the licensee files with the Commission a request for exemption from the requirements of section 50.46.and such rqquest is granted. Dated at Bethesda, Maryland, this k day of Actja h / FOR THE ATOMIC ENERGY COMMISSION (signed) L. Manning Munt:ing L. Manning Muntzing Director of Regulation - k(ken [,4/ 4 {als /M

p.==

q

}

$ hl-( ~ L:0 RB-28 /7 ft$fjver:e/deyl0GC--- y L:AD/0Rs p L:DD P R DIR = j s ""cE > 2 - p--- fjs H ygg RMDiggs Jaccaer KRGoller AGiam sso E rse. LHMu t' hf""~~Bl$l74 8/5'/74 };..~.' 5l[)74 '5) h4 _ l ~ ~ 8/f, / ,. _ a c.3i,ta...s3, Tr o i 24. ~ 1. .}}