Ex Parte Patel et al

Board of Patent Appeals and Interferences

May 10, 2010

11220672 (B.P.A.I. May. 10, 2010)

UNITED STATES PATENT AND TRADEMARK OFFICE
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BEFORE THE BOARD OF PATENT APPEALS
AND INTERFERENCES
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Ex parte RAMESH PATEL, ALBERT TSANG,
JAMES SAWABE, and HWANG CHOE
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Appeal 2009-012760
Application 11/220,672
Technology Center 2800
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Decided: May 10, 2010
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Before CHUNG K. PAK, TERRY J. OWENS, and PETER F. KRATZ,
Administrative Patent Judges.

OWENS, Administrative Patent Judge.

DECISION ON APPEAL
STATEMENT OF THE CASE
The Appellants appeal under 35 U.S.C. § 134(a) from the Examiner’s
rejection of claims 1-14, which are all of the pending claims. We have
jurisdiction under 35 U.S.C. § 6(b).
The Invention
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The Appellants claim a liquid level measurement system and method.
Claims 1 and 10 are illustrative:
1. A liquid level measurement system for measuring a liquid level in a
monitored vessel that contains a volume of liquid having an upper surface,
and vapor with non-condensable gases comprising:

a condensing chamber configured to hold a first volume of liquid and
to condense the vapor;

a steam leg extending between the monitored vessel and the
condensing chamber for introducing the vapor and non-condensable gases
into the condensing chamber;

a variable leg for receiving liquid from the condensing chamber and
introducing the received liquid into the monitored vessel at a point below the
upper surface of the liquid;

a reference leg for receiving liquid from a liquid source and
introducing the liquid into the condensing chamber; and

a differential pressure sensor arranged between the variable leg and the
reference leg for measuring a pressure difference.
10. A method for measuring a liquid level in a monitored vessel that
contains a volume of liquid having an upper surface, and vapor with non-
condensable gases comprising:
introducing vapor from the monitored vessel into a condensing
chamber and condensing a portion of the vapor to form liquid at a first rate
Ls;
continuously introducing liquid into the condensing chamber, from a
liquid source, at a second rate Lr through a reference leg;
continuously removing liquid from the condensing chamber at a third
rate Lv through a variable leg and returning it to the monitored vessel,
wherein, on average, the expression
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Ls + Lr = Lv
is satisfied, thereby maintaining an average reference liquid level in the
condensing chamber and establishing a variable liquid level in the variable
leg; and
sensing a pressure difference between the reference liquid level and the
variable liquid level.
The References
Oldenhage 5,475,720 Dec. 12, 1995
Ishii (as translated) JP 06-094506 A Apr. 5, 1994

The Rejections
The claims stand rejected as follows: claims 1-9 under
35 U.S.C. § 102(b) over Oldenhage, and claims 10-14 over Oldenhage in
view of Ishii.
OPINION
We reverse the rejections.
Rejection of claims 1-9
Issue
Have the Appellants indicated reversible error in the Examiner’s
determination that Oldenhage discloses a reference leg for receiving liquid
from a liquid source and introducing the liquid into a condensing chamber?
Findings of Fact
Oldenhage discloses a liquid level measurement system comprising a
condensing chamber (100), a steam leg between a pressure vessel (10) and
the condensing chamber (100), a variable leg (44) for receiving liquid from
the condensing chamber (100) and introducing the received liquid into the
pressure vessel (10) at a point below the upper surface of liquid therein, a
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reference leg (16), and a differential pressure sensor (18) between the
variable leg (44) and the reference leg (16) for measuring a pressure
difference (col. 7, l. 63 – col. 8, l. 3; col. 9, ll. 7-9, 47-49; Fig. 2).
Oldenhage does not disclose that the reference leg is capable of receiving
liquid from a liquid source and introducing the liquid into the condensing
chamber.
Oldenhage discloses that prior art efforts to avoid non-condensable
gases in a reference leg which can cause significant errors in measuring the
water level in a pressure vessel have focused on removing non-condensable
gases from a condensing chamber before elevated levels can accumulate
(col. 4, ll. 40-43; col. 5, ll. 32-34). In this regard Oldenhage discloses
(col. 6, ll. 9-16):
An automatic keepfill system, providing continuous backfill of
reference leg 16, is a fourth possible solution. The NRC [Nuclear
Regulatory Commission] Staff endorsed the continuous backfill
modification as an acceptable solution to the degassing problem.
Such a system is under investigation, and has been adopted by much
of the utility industry, but requires relatively extensive modifications
to piping and valving. Moreover, the keepfill system may not be
feasible at certain plants.

Analysis
The Appellants argue that “Oldenhage’s discussion of an automatic
keepfill system is simply listed among several unfavorable alternatives
described in column 5, line 25 through column 6, line 44 of the Background
of the specification” (Br. 10).
The Examiner argues that Oldenhage’s disclosure regarding the
automatic keepfill system (col. 6, ll. 9-15) is a disclosure of a reference leg
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for receiving liquid from a liquid source and introducing the liquid into the
condensing chamber (Ans. 3).
The Examiner has the initial burden of establishing a prima facie case
of anticipation by pointing out where all of the claim limitations appear in a
single reference. See In re Spada, 911 F.2d 705, 708 (Fed. Cir. 1990); In re
King, 801 F.2d 1324, 1327 (Fed. Cir. 1986). Oldenhage’s automatic keepfill
system is not disclosed as being part of Oldenhage’s system but, rather, is
disclosed as being an alternative way to remove non-condensable gases from
a condensing chamber (col. 5, ll. 33-35; col. 6, ll. 9-16). Hence, the
Examiner has not carried the burden of establishing that Oldenhage discloses
a system that includes each element of the Appellants’ independent claim 1,
which is the sole independent claim among claims 1-9.
Conclusion of Law
The Appellants have indicated reversible error in the Examiner’s
determination that Oldenhage discloses a reference leg for receiving liquid
from a liquid source and introducing the liquid into a condensing chamber.
Rejection of claims 10-14
Issue
Have the Appellants indicated reversible error in the Examiner’s
determination that the applied prior art would have rendered prima facie
obvious, to one of ordinary skill in the art, continuously introducing liquid
from a liquid source through a reference leg into a condensing chamber?
Findings of Fact
Ishii discloses a differential pressure water level measurement device
(¶ 0001; Fig. 1). When the pressure in a tank (1) becomes negative due to
variations in a plant’s load, water is sucked from a reference level vessel (2)
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into the tank (1), causing the reference water level to decrease (¶ 0011). The
change in the reference water level is detected by a level switch (4) on a
reference level pipe (6) having the same water level as the reference level
vessel. See id. A signal from the level switch (4) automatically operates a
water resupply valve (5) to replenish the water in the reference level
vessel (2) such that its water level is restored. See id.
Analysis
The Appellants argue that Oldenhage does not disclose how an
automatic keepfill system interrelates a reference leg with a condensing
chamber, and that Ishii does not continuously introduce liquid into a
condensing chamber (Br. 10-13).
The Examiner argues that “[i]f a keepfill were used with Oldenhage’s
system, it would necessarily introduce water into the condensing chamber
because the level of water in the reference leg and condensing chamber must
be at least up to the height of the exit 80 in the variable leg” (Ans. 11).
Establishing a prima facie case of obviousness of an invention
comprising a combination of known elements requires “an apparent reason
to combine the known elements in the fashion claimed.” KSR Int’l. Co. v.
Teleflex Inc., 550 U.S. 398, 418 (2007). The Examiner has not established
that one of ordinary skill in the art would have had an apparent reason to use
an automatic keepfill system in Oldenhage’s system. Oldenhage excludes
non-condensable gases from the reference leg (16) by using condensation on
the interior walls of a vent leg (60) to draw non-condensable gases from
steam (30) into the vent leg (60) where they diffuse into water (20) in the
vent leg and are returned to the pressure vessel (10) (col. 9, ll. 47-60). “As
long as condensation occurs in the system, the effect of the non-condensable
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gases will be removed from vapor space 98 of condensing chamber 100 and,
therefore, those gases will be excluded from reference leg 16” (col. 10,
ll. 10-14). The automatic keepfill system mentioned by Oldenhage is an
alternative system for removing non-condensing gases from a condensing
chamber (col. 5, ll. 32-34; col. 6, ll. 9-16), and the Examiner has not set forth
an apparent reason why one of ordinary skill in the art would have combined
them. Furthermore, in the Examiner’s argument that an automatic keepfill
system which provides a continuous backfill of Oldenhage’s reference
leg (16) necessarily would introduce water into the condensing
chamber (100) (Ans. 11), the Examiner is relying upon that introduction of
water as being an inherent characteristic of the combined system. An
inherent characteristic must be inevitable, and not merely a possibility or
probability. See In re Oelrich, 666 F.2d 578, 581 (CCPA 1981). The
Examiner has not established that water introduced into Oldenhage’s
reference leg (16) inevitably would enter the condensing chamber (100)
rather than merely keeping the reference leg (16) filled. The Examiner has
not provided enough information about automatic keepfill systems to
support the Examiner’s finding of inherency.
The Examiner argues that “[t]he fact that the reference leg must be
kept filled to the same level (Oldenhage, column 2, lines 19-21), and that the
reference leg can be continuously backfilled (Oldenhage, column 6, lines 9-
14), coupled with Ishii’s system of filling the condensing chamber from a
water source (Ishii, page 2, lines 6-8), via the reference leg (Ishii, page 2,
lines 8-10) amounts to a system of continuously filling the condensing
chamber via the reference leg” (Ans. 8).
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Oldenhage’s disclosure relied upon by the Examiner as teaching that
the reference leg can be continuously backfilled (col. 6, ll. 9-14) pertains to
the automatic keepfill system. As discussed above, the Examiner has not
established that one of ordinary skill in the art would have had an apparent
reason to combine an automatic keepfill system with Oldenhage’s system.
As for the Examiner’s reliance upon Ishii for a disclosure of restoring the
water level in a condensing chamber from a water source through a
reference leg (Ans. 8, 13), neither Ishii’s tank (1) nor Ishii’s reference level
vessel (2) is disclosed as being a condensing chamber, and the portion of
Ishii (page 2, ll. 8-10) relied upon by the Examiner (Ans. 8) does not state
that the water enters either the tank (1) or the reference level vessel (2) via
the reference level pipe (6). Hence, the Examiner has not established a
factual basis in Ishii which supports the Examiner’s argument. Moreover,
the Examiner’s argument that combining Oldenhage’s system with an
automatic keepfill system and Ishii’s system “amounts to a system of
continuously filling the condensing chamber via the reference leg” (Ans. 8)
is not persuasive because the Examiner has not established that one of
ordinary skill in the art would have had an apparent reason for making that
combination. See KSR, 550 U.S. at 418.
Thus, the Examiner has not carried the burden of establishing a prima
facie case of obviousness of the Appellants’ claimed method.
Conclusion of Law
The Appellants have indicated reversible error in the Examiner’s
determination that the applied prior art would have rendered prima facie
obvious, to one of ordinary skill in the art, continuously introducing liquid
from a liquid source through a reference leg into a condensing chamber.
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DECISION/ORDER
The rejections of claims 1-9 under 35 U.S.C. § 102(b) over Oldenhage
and claims 10-14 over Oldenhage in view of Ishii are reversed.
It is ordered that the Examiner’s decision is reversed.
REVERSED

PL Initial:
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