ML20054A163
| ML20054A163 | |
| Person / Time | |
|---|---|
| Site: | Haddam Neck File:Connecticut Yankee Atomic Power Co icon.png |
| Issue date: | 04/12/1982 |
| From: | Crutchfield D Office of Nuclear Reactor Regulation |
| To: | Counsil W CONNECTICUT YANKEE ATOMIC POWER CO. |
| References | |
| TASK-15-10, TASK-RR LSO5-82-04-032, LSO5-82-4-32, NUDOCS 8204150320 | |
| Download: ML20054A163 (9) | |
Text
1 Ar-April 12,1982
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LS05-82-04-032
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Docket No. 50-213 E/Vgg 4
PR15 2.
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8 Mr. W. G. Counsil Vice President D
Nuclear Engineering and Operations o
Connecticut Yankee Atomic Power Company as 6
Post Office Box 270 Hartford, Connecticut 06101
Dear Mr. Counsil:
SUBJECT:
HADDNi NECK - SEP TOPIC XV-10 CHEMICAL AND VOLUME CONTROL SYSTEM MALFUNCTI0tl THAT RESULTS Iti A DECREASE IN BORON CONCENTRATION Ifl THE REACTOR COOLANT By letter dated September, 30, 1981, you submitted a safety assessment report for the above topic. The staff has reviewed this assessment and our conclusions are presented in the enclosed safety evaluation report, which completes the review of this topic for the Haddam Neck plant.
This evaluation will be a basic input to the integrated assessment for your facility. The evaluation may be revised in the future if your facility design is changed or if NRC criteria relating to this topic are modified before the integrated assessment is completed.
Sincerely, gginal siinad by; Dennis it. Crutchfield, Chief Operating Reactors Branch No. 5 Division.of Licensing
Enclosure:
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OFFICIAL RECORD COPY usc.m im-mm me ronu sta p>so> sacu eno
Haddam Neck '
Docket No. 50-213 Revised 3/30/82 Mr. W. G. Counsil
~
CC Day, Berry & Howard Counselors at Law One Constitution Plaza Hartford, Connecticut 06103 Superintendent Haddam Neck Plant RFD #1' Post Office Box 127E East Hampton, Connecticut 06424
. Mr. Richard R. Laudenat Manager, Generation Facilities Licensing Northeast Utilities Service Company P. O. Box 270 Hartford, Connecticut 06101 Board of Selectmen Town Hall Haddam, Connecticut 06103 State of Connecticut 0Ffice of Policy and Management ATTN:
Under Secretary Energy Division 80 Washington Street Hartford, Connecticut 06115 U. S. Environmental Protection Agency Region I Office ATTN:
Regional Radiation Representative JFK Federal Building Boston, Massachusetts 02203 Resident Inspector Haddam Neck Nuclear Power Station c/o'U. S..NRC East Haddam Post Office East Haddam, Connecticut 06423 Ronald C. Haynes, Regional Administrator Nuclear Regulatory Commission, Region I 631 Park Avenue King of Prussia, Pennsylvania 19406
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l l
HADDAM NECK, }$P TOPIC XV-10 EVALUATION x
s CHEMICAC AND VOLUME CONTROL SYSTEM MALFUNCTION.THAT RESULTS IN A DECREASE IN BORON CONCENTRATION IN THE REACTOR COOLANT I.
INTRODUCTION A decrease in the boron concentration in the reactor coolant-adds reactivity to the core.
This produces a loss of shutdown margin or power and temperature increases, depending on the condition of the core at the time of the loss of boron.
The concentration of boron in the Haddam Neck reactor coolant can be decreased by adding unborated water at a maximum rate of 180 gpm.
To prevent an inadvertent criticality, the operator must stop an unplanned decrease in boron concentration before the shutdown margin is eliminated by closing valves and shut-ting off the primary water transfer pumps.
The Connecticut Yankee Atomic Power Company (CYAPCO) first analyzed the boron dilution event for the Facility Descrip-tion and Safety Analysis report in 1966 (Reference 1).
At the request of the NRC in 1978, CYAPCO did a reevaluation of all potential boron dilution accidents at Haddam Neck.
The a
l results of this, which confirmed the conclusions of Refer-i j
ence 1, were reported in Reference 2.
In 1981, the NRC re-A quested CYAPCO to confirm that the operators at Haddam Neck f
have at least 15 minutes after an alarm to terminate the t
. dilution flow before an inadvertent criticality occurs.
Re-s
' ference 3 provided this. coni'irmation.
In Reference 4, CYAPCO
\\ summarized theoresults of all the analyses it had performed on potential boron dilution accidents at the Haddam Neck plant.
f The Technical Specifications (Reference 5) provide current operating limits.
II.
REVIEW CRITERIA Section 50.34 of 10 CFR Part 50 requires that each applicant for a construction permit or operating license provide an ana-lysis and evaluation of the design and performance of struct-ures, systems, and components of the facility with the ob-jective of assessing the risk to public health and safety resulting from operation of the facility, including deter-i mination of the margins of safety during normal operations and transient conditions anticipated during the life of the facility.
Section 50.36 of 10 CFR Part 50 requires the Technical Speci-l fications to include safety limits which protect the integrity i
of the physical barriers which guard against the uncontrolled release of radioactivity.
The General Design Criteria (Appendix A to 10 CFR Part 50) es-tablish minimum requirements for the principal design criteria for water-cooled reactors.
i k
GDC 10 " Reactor Design" requires that the core and associated i
coolant, control, and protection systems be designed with
. appropriate margin to assure that specified acceptable fuel
,~
design limits are not exceeded during normal operation, in-
\\cluding the e~f fects.of anticipated operational occurrences.
GDC 15 " Reactor Coolant System Design" requires that the re-actor coolant and associ,ated protection systems be designed with sufficient margin to assure that the design conditions of the reactor coolant pressure boundary are not exceeded during normal operation, including the ef fects of anticipa-ted operational occurrences.
GDC 26 " Reactivity Control Systen Redundancy and Capability" requires that the reactivity control systems be capable of re-liably controlling reactivi ty changes to assure that under conditions of normal operation, including anticipated oper-ational occurrences, and with appropriate margin for mal-functions such as stuck rods, specified acceptable fuel de-sign limits are not exceeded.
III.
RELATED SAFETY TOPICS Various other SEP topics evaluate such items as the reactor protection system.
The effects of single failures on safe shutdown capability are considered under Topic VII-3.
VI.
R.EVIEW GUIDELINES l
The review is conducted in accordance with SRP 15.4.6.
The evaluation includes review of the analysis for the event and identification of the features in the plant that mitigate pW*
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-4
.~
'the consequences of the event as well as the ability of these ksystems to func, tion as required.' The' extent to which operator action is required is also evaluated.
Deviations from the cri-f teria specified in the Standard Review Plan are identified.
V.
EVALUATION P
As stated in Reference 4, the maximum positive reactivity in-N sertion l
rate that can be obtained by diluting the boron concen-l tration in the reactor water at the Haddam Neck plant is i
1.4 x 10-5 ok per second.
This is almost on order of magni-tude less than the 2.25 x 10-4 ak per second rate used for the analysis of control rod withdrawal incidents (Reference 6).
Thus, the consequences of a boron dilution accident are less severe than those for the postulated control rod withdrawal a cci den t (Reference 7) ; so the automatic features of the Re-actor Protection System can prevent the departure from nucle-ate boiling (DNB) ratio from going below the Technical Speci-fication minimum value of 1.3 during any boron dilution acci-dent.
1 l
When the Haddam Neck reactor is subcritical in Modes 3, 4, or S technical specificctions (Ref. 5) require that except during f
k physics testing, a 3 percent Ak shutdown margin shall be main-tained.
Technical Specifications also ret uire that for refueling Mode 6, the boron in the reactor water will provide an 8 percent Ak shutdown margin.
Thus, a boron dilution event at the maximum rate of.0014 percent ok per second will allow considerable time for the operator to stop the dilution before criticality is
)
attained.
o for Modes 3 through 6 Reference 8 states that there are two
'indepcndent source range channels of nuclear instrumentation and that each' channel provides alarm signals in the main con-trol room.
Reference 9 states that there are two independent intermediate range channels of nuclear instrumentation and that each channel provid.es trip signals to the reactor pro-tection system when going f' rom Mode 3 to Mode 2.
Reference 9 also states that for Mode 1 there are four independent power channels which provide reactor trip signals.
Thus, the oper-ator will be alerted to inadvertent boron dilution even with a failure of the first alarm.
As stated in Reference 1, a mininum reactor coolant volume of 2800 cubic fcet was assumed for ': ode 6.
This is the amount of coolant needed to fill the reactor vessel to the nozzles.
It is Icss than the volume of coolant in the system when it has a partially drained hot leg.
If this volume is assumed the minir:um time to criticality is about 55 r.inutes for Mode 6 and alcat 20
.inutes for Mode 5.
l In sunmary, Haddam Neck meets the time r e q u i r e n.e n t s associated with SRP Section 15.4.6, that is, for operation of Mode 1 through 5,
there must be at (cast 15 minutes between alarm and criticality and for Mode 6,
the operator rust have at least 30 minutes between i
alarm and criticality.
l l
e VI.
CONCLUSION 2
a.As part of the.SEP review for Haddam Neck, the analyses for a chemical and volume control system malfunction that results in a decrease in boron' concentration in the reactor coolant has been evaluated.
We have concluded that all of the conse-quences of this event are in conformance with the criteria of SRP Section 15.4.6 and are therefore acceptable.
l 1
f l
I
liADDAM NECK XV-10 REFERENCES 1.
Connecticut Yankee Atomic Power Company; Facility Description and
'S a f e_ty_ lea ly s i_s,._ volume 1_1_ ; serlin, Connecticut; pages 10.2.3-1 to 10.2.3-4; May, 1966."
2.
- Letter, D.
C. Switzer o'f CYAPCO to A.
Schwencer of NRC, dated Jan-uary 13, 1978.
3.
- Letter, W.
G.
Counsil of CYAPCO to D.
Crutchfield of NRC, dated August 13, 1981.
4.
- Letter, W.
G.
Counsil of CYAPCO to D.
Crutchfield of NRC, dated September 30, 1981.
5.
Connecticut Yankee Atomic Power Company; A;1pendix A to Facility O p_ratina. License f)_PR-A Technical Speci fi ca tions for the Conn-l ecticut Y_a n) ee Atomic Power _ Company; lia d d am, Connecticut; as re-vised to Anendment No. 46, January 1982.
6.
Connecticut Yankee Atomic Power Company; Facility Description and S a 9' tlj.nj: 1_ysis, Volu3e I; he rl in, Connecticut; page 10.2.1-3; May, 1966.
7.
ibid; Figures 10.2.1-1 to 10.2.1-6.
8.
ibid; page 7.3-1.
9.
ibid; page 7.3-2.
.